The present invention relates to a buttonhole darning sewing machine for forming a buttonhole darning seam in a cloth while swinging a needle in tune with the feeding operation of the cloth, a buttonhole darning sewing machine for forming a buttonhole in a cloth using a cloth cutting knife, and a sewing apparatus including such buttonhole darning sewing machine.

In a buttonhole darning sewing machine for forming a buttonhole darning seam in a cloth while swinging a needle in tune with the feeding operation of the cloth and also for forming a buttonhole in a cloth using a cloth cutting knife, conventionally, as known well from Japanese Utility Model Publication No. 7-43305 of Heisei and the like, a cloth feed mechanism, a needle swing mechanism, a needle swing width change mechanism, and a base line change mechanism are respectively operated due to the rotation of a main cam which can be rotated in linking with the main shaft of the sewing machine.

And, recently, as known well from Unexamined Japanese Patent Application Publication No. 6-190164 of Heisei, there are provided a cloth feed motor, a needle swing width change motor, and a base line change motor, and, by driving or controlling these three motors, the cloth feed mechanism, needle swing width change mechanism, and base line change mechanism are respectively operated.

Also, referring to the cloth cutting knife, conventionally, as known well from Japanese Patent Publication No. 7-14438 of Heisei and the like, the cloth cutting knife is structured such that it is moved up and down once due to the rotation of the above-mentioned main cam.

And, conventionally, there are prepared cloth cutting knives respectively including cutting edges which correspond in length to buttonholes having different lengths; and, a cloth cutting knife corresponding to a given buttonhole is mounted on a knife mounting plate, and a buttonhole is formed in a cloth by moving up and down the cloth cutting knife once.

In forming a buttonhole using a cloth cutting knife in this manner, there are available a front knife cutting processing or operation which is previously executed prior to formation of a buttonhole darning seam, and a rear knife cutting processing which is executed after completion of formation of a buttonhole darning seam; and, there is also available a processing which is executed by moving down the cloth cutting knife just before completion of formation of a buttonhole darning seam.

In the case of the above-mentioned cloth cutting knife which is structured such that it is moved up and down once due to the rotation of the main cam, as described above, it is necessary to have prepared the cloth cutting knives which respectively include cutting edges corresponding in length to the different-length buttonholes. This not only raises a problem that the number of parts required is large but also requires a troublesome operation to mount a corresponding cloth cutting knife onto a knife mounting plate each time a buttonhole is changed.

JP-A-03 085196 discloses a buttonhole darning sewing machine according to the preamble portion of claim 1.

Accordingly, it is an object of the invention to be able to form a plurality of buttonholes differing in length from each other by a single cloth cutting knife with no need for replacement of the cloth cutting knife.

Also, it is another object of the invention to provide a sewing apparatus which is capable of mounting only a special part such as a special cloth cutting knife or the like onto a special-purpose sewing machine such as a special buttonhole darning sewing machine or the like.

Further, it is still another object of the invention to provide a buttonhole darning sewing machine on which only a special cloth cutting knife can be mounted.

In solving the above problems, a first aspect of the invention provides a buttonhole darning sewing machine which comprises a cloth hold plate disposed along the upper surface of a sewing machine bed, and a cloth presser for moving the cloth hold plate at least in the longitudinal direction of the sewing machine bed in tune with the upward-and-downward movement of a needle provided in the sewing machine while holding a cloth between the cloth hold plate and itself, in which a buttonhole darning seam comprising right and left side sewing portions to be formed on the right and left side portions of a long and narrow buttonhole and a lock stitch sewing portion to be formed at least in one end portion of each of the right and left side sewing portions is formed, and a buttonhole having a length corresponding to the above side sewing portions is formed within the buttonhole darning seam along the right and left side sewing portions by means of a cloth cutting knife, characterized by the cloth cutting knife which includes a cutting edge having a length set shorter than the length of the side sewing portions, and by control means for moving the cloth cutting knife up and down two or more times to thereby form the buttonhole having a length corresponding to the length of the side sewing portions.

Here, the cloth cutting knife is a knife which can be moved up and down to thereby form a buttonhole in a cloth; and, the cloth cutting knife includes a cutting edge in the lower portion thereof, while the length of the cutting edge is set shorter than the length of the side sewing portions.

In the first aspect, with use of the present buttonhole darning sewing machine, a buttonhole having an arbitrary length can be formed using a single kind of cloth cutting knife, which not only eliminates the need for replacement of the cloth cutting knife even when the length of the buttonhole is changed but also eliminates the need for preparation of cloth cutting knives corresponding in number to buttonholes different in length from each other.

According to a second aspect of the invention, there is provided with the buttonhole darning sewing machine of the first aspect, in which the above-mentioned cloth cutting knife is structured such that, during formation of the stitches of the above-mentioned side sewing portions, it is moved up and down once each time a given length of stitch is formed.

In the second aspect, at first, a given number of stitches of the side sewing portions are formed and, after then, the buttonhole is formed. Therefore, the stitches of the side sewing portions can be obtained stably. Also, since the cloth cutting knife is moved up and down once after a given number of stitches are formed, the buttonhole can be formed sharply.

Or, when the cloth cutting knife is moved up and down two or more times, the last upward-and-downward movement of the cloth cutting knife may also be carried out during formation of the lock stitch sewing portion. For example, when the cloth cutting knife is moved up and down two times, the first upward-and-downward movement of the cloth cutting knife may be carried out during formation of the side sewing portions the lock stitch portion and the second upward-and-downward movement of the cloth cutting knife may be carried out during formation of the lock stitch sewing portion.

According to a third aspect of the invention, there is provided the buttonhole darning sewing machine of the second aspect, in which the above-mentioned cloth cutting knife is structured such that it is moved up and down once each time a given number of stitches are formed in the side sewing portions.

In the third aspect, at first, since a buttonhole is formed after formation of a given number of stitches in the side sewing portions, the stitches of the side sewing portions can be obtained stably; and, because the cloth cutting knife is moved up and down once each time a given number of stitches are formed in the side sewing portions, the material of the cloth is reinforced by the thus formed side sewing portions, so that the buttonhole can be formed sharply.

According to a fourth aspect of the invention, there is provided the buttonhole darning sewing machine of the third aspect, in which the above-mentioned given number of stitches are set in accordance with both of the length of the cutting edge of the cloth cutting knife and the length of the buttonhole.

As described above, according to the fourth aspect of the invention, since there is provided a buttonhole darning sewing machine, in which the given number of stitches as set forth in the third aspect are set in accordance with both of the length of the cutting edge of the cloth cutting knife and the length of the buttonhole, the given number of stitches can be set properly in accordance with both of the length of the cutting edge of the cloth cutting knife and the length of the buttonhole.

According to a fifth aspect of the invention, there is provided the buttonhole darning sewing machine of the first aspect, in which the control means includes electrical moving means comprising a pulse motor, a connecting mechanism, a cloth hold arm or the like, for moving the cloth presser by a given distance in accordance with a given feed signal, electrical drive means comprising a cylinder unit or the like for moving the cloth cutting knife in accordance with an operation signal, and knife control means included in a CPU or the like for generating the operation signal in synchronization with the feed signal indicating a given amount of feed to thereby move the cloth cutting knife up and down.

For example, as the electrical moving means, as described above, there can be used a structure which consists of a pulse motor, a connecting mechanism, a cloth hold arm or the like; however, this is not limitative but other structures can also be used.

As the electrical drive means, for example, there is available a cylinder unit; but, there can also be used other structures such as a solenoid, and the like.

The knife control means can be included in a CPU or the like.

In the fifth aspect, with use of the present buttonhole darning sewing machine, the cloth presser is moved by a given length by the electrical moving means in accordance with the feed signal indicating a given amount of feed and, in synchronization with the feed signal, an operation signal is generated by the knife control means to thereby move the cloth cutting knife up and down; that is, through this operation, the cloth cutting knife can be moved up and down two or more times in tune with the cloth feeding operation, so that a buttonhole can be formed positively.

According to a sixth aspect of the invention, there is provided the buttonhole darning sewing machine as set forth in the fifth aspect, in which the above-mentioned given amount of feed is set in accordance with both of the length of the cutting edge of the cloth cutting knife and the length of the buttonhole.

In the sixth aspect, a given cloth feed amount can be set properly in accordance with both of the length of the cutting edge of the cloth cutting knife and the length of the buttonhole.

According to a seventh aspect of the invention, there is provided the buttonhole darning sewing machine as set forth in the first aspect, which further includes knife upper and lower position detect means such as a close approach type of switch for detecting the upper or lower position of the cloth cutting knife to thereby generate a detect signal, and sewing machine control means included in a CPU or the like for checking whether the detect signal from the knife upper and lower position detect means is present or not and, if not present, for causing the present sewing machine to stop.

As the knife upper and lower position detect means, as described above, there is available a close approach type of switch but there can also be used a contact type of switch or a non-contact type of sensor.

Also, the sewing machine control means, as described above, can be included in a CPU or the like.

In the seventh aspect, when the detect signal from the knife upper and lower position detect means is not generated, it can be judged that the operation of the cloth cutting knife is out of order, so that the operation of the present sewing machine can be stopped by the sewing machine control means.

According to an eighth aspect of the invention, there is provided the buttonhole darning sewing machine as set forth in the first aspect, in which the cloth cutting knife can be moved up and down prior to or after the formation of the buttonhole darning seam.

The eighth aspect of the invention makes it possible to carry out not only a front knife cutting processing in which a buttonhole can be previously formed by two or more times of upward-and-downward movement of the cloth cutting knife before formation of the buttonhole darning seam, but also a rear knife cutting processing in which a buttonhole can be formed by two or more times of upward-and-downward movement of the cloth cutting knife after formation of the buttonhole darning seam.

According to a ninth aspect of the invention, there is provided the buttonhole darning sewing machine as set forth in the first aspect, in which the cloth cutting knife, after formation one of the right and left side sewing portions, can be moved up and down while the other of them is being formed.

In the ninth aspect, since the buttonhole is formed by moving up and down the cloth cutting knife after formation of one of the right and left side sewing portions and during formation of the other, not only the stitches of the right and left side sewing portions can be obtained stably but also the buttonhole can be formed sharply.

According to a tenth aspect of the invention, there is provided the buttonhole darning sewing machine as set forth in the first or ninth aspect, in which, during the upward-and-downward movement of the cloth cutting knife, the speed of the present sewing machine set for a knife driving time is reduced down to zero or a speed near zero.

In the tenth aspect, with use of this invention, it is possible to prevent the cloth from shifting out of position in the upward-and-downward movement of the cloth cutting knife.

According to an eleventh aspect of the invention, there is provided a buttonhole darning sewing machine in which a buttonhole darning seam comprising right and left side sewing portions to be formed on the right and left sides of a long and narrow buttonhole and a lock stitch sewing portion to be formed at least in one end portion of the right and left side sewing portions is formed, and a buttonhole having a length corresponding to said side sewing portions is formed within said buttonhole darning seam by moving a cloth cutting knife along said side sewing portions, characterized by control means which is able to control or set the cloth cutting knife selectively into a front knife cutting operation in which the cloth cutting knife is moved up and down before formation of the buttonhole darning seam to thereby form the buttonhole, a middle knife cutting operation in which the cloth cutting knife is moved up and down during formation of the buttonhole darning seam to thereby form the buttonhole, and a rear knife cutting operation in which the cloth cutting knife is moved up and down after formation of the buttonhole darning seam to thereby form the buttonhole.

Here, the cloth cutting knife is a knife which can be moved up and down to thereby form a buttonhole in a cloth, while the cloth cutting knife includes a cutting edge in the lower portion thereof.

The knife control means can be included in a CPU or the like.

In the eleventh aspect, with use of the present invention, it is possible to carry out selectively any one of the three knife cutting operations: that is, the front knife cutting operation in which the cloth cutting knife is moved up and down before formation of the buttonhole darning seam to thereby form the buttonhole, the middle knife cutting operation in which the cloth cutting knife is moved up and down during formation of the buttonhole darning seam to thereby form the buttonhole, and the rear knife cutting operation in which the cloth cutting knife is moved up and down after formation of the buttonhole darning seam to thereby form the buttonhole.

According to a twelveth aspect of the invention, there is provided the buttonhole darning sewing machine in which a buttonhole darning seam comprising right and left side sewing portions to be formed on the right and left sides of a long and narrow buttonhole and a lock stitch sewing portion to be formed at least in one end portion of the right and left side sewing portions is formed, and a buttonhole having a length corresponding to said side sewing portions is formed within said buttonhole darning seam along the side sewing portions thereof by means of a cloth cutting knife, characterized by control means which moves the cloth cutting knife up and down during formation of the side sewing portions of the buttonhole darning seam to thereby form the buttonhole, and by knife downward-movement start timing setting means for setting the downward-movement start timing of the cloth cutting knife during formation of the side sewing portions.

Here, the knife control means can be included in a CPU or the like.

As the knife downward-movement start timing setting means, for example, there can be used a knife drop switch which can be operated in correspondence to the cloth feeding operation. However, this is not limitative but other types of switches can also be used.

In the twelveth aspect, the cloth cutting knife can be moved up and down at the thus properly set downward-movement start timing to thereby be able to form a given buttonhole.

According to a thirteenth aspect of the invention, there is provided the buttonhole darning sewing machine as set forth in the twelveth aspect, further including buttonhole/knife cutting edge length setting means for setting not only the length of the buttonhole but also the length of the cutting edge of the cloth cutting knife, and operation means included in a CPU or the like for operating the downward-movement timing of the cloth cutting knife in accordance with not only the length of the buttonhole but also the length of the cutting edge of the cloth cutting knife set by the buttonhole/knife cutting edge length setting means.

The buttonhole/knife cutting edge length setting means is means which is used to carry out various settings/operations on an operation panel.

The operation means, as described above, can be included in a CPU or the like.

In the thirteenth aspect, the proper down-movement timing of the cloth cutting knife can be operated by the operation means in accordance with not only the length of the buttonhole but also the length of the cutting edge of the cloth cutting knife set by the buttonhole/knife cutting edge length setting means.

According to a fourteenth aspect of the invention, there is provided the buttonhole darning sewing machine as set forth in the twelveth aspect, in which the knife downward-movement start timing setting means includes electrical moving means, such as a structure comprising a pulse motor, a connecting mechanism, a cloth hold arm and the like, for moving the cloth presser by a given distance along the side sewing portions in response to a given feed signal, and sewing movement position detect means, such as a feed sensor of a close approach type, for detecting the sewing movement position of the side sewing portions, characterized in that the cloth cutting knife can be moved downward in accordance with a detect signal generated by the sewing movement position detect means.

As the electrical moving means, for example, there can be used a structure which consists of a pulse motor, a connecting mechanism, a cloth hold arm and the like. However, it is also possible to employ another structure.

As the sewing movement position detect means, for example, there can used a feed sensor of a close approach type. However, it is also possible to employ a sensor of other type, a switch or the like.

In the fourteenth aspect, due to the downward-movement of the cloth cutting knife in synchronization with the cloth feeding operation, the buttonhole can be formed properly.

According to a fifteenth asepct of the invention, there is provided the buttonhole darning sewing machine as set forth in the twelveth aspect, in which the knife downward-movement start timing setting means includes buttonhole formation position setting means for setting the formation position of the buttonhole in a direction extending along the cloth feed direction of the buttonhole darning seam, such as means for carrying out various settings/operations on an operation panel, and knife downward-movement timing decide means included in a CPU or the like for deciding the downward-movement timing of the cloth cutting knife according to the count of stitches or the count of cloth feed pulses in accordance with the above setting made by the buttonhole formation position setting means.

As the buttonhole formation position setting means, for example, there can be used means for carrying out various settings/operations on an operation panel.

And, the knife downward-movement timing decide means can be included in a CPU or the like.

In the fifteenth aspect, with use of this invention, the whole of the knife drop position can be moved in accordance with the downward-movement timing of the cloth cutting knife.

According to a sixteenth aspect of the invention, there is provided a buttonhole darning sewing machine in which a buttonhole darning seam comprising right and left side sewing portions to be formed on the right and left sides of a long and narrow buttonhole and a lock stitch sewing portion to be formed at least in one end portion of the right and left side sewing portions is formed, and a buttonhole having a length corresponding to the side sewing portions is formed within the buttonhole darning seam along the side sewing portions thereof by means of a cloth cutting knife, characterized by gap setting means for setting a gap between the lock stitch sewing portion and the end portion of the buttonhole, such as means for carrying out various settings/operations on an operation panel, side sewing length change means included in a CPU or the like for changing the length of the side sewing portions without changing the cloth cutting length in accordance with the above setting by the gap setting means, and knife downward-movement timing decide means included in a CPU or the like for deciding the timing of the downward-movement timing of the cloth cutting knife in accordance with the above change made by the side sewing length change means.

Here, the gap setting means is means for carrying out various settings/operations on an operation panel.

Also, the side sewing length change means and knife downward-movement timing decide means are both included in a CPU.

In the sixteenth aspect, with use of this invention, the gap between the lock stitch sewing portion and the knife drop position can be corrected in accordance with the downward-movement timing of the cloth cutting knife.

According to a seventeenth aspect of the invention, there is provided a buttonhole darning sewing machine for forming a buttonhole of a given length by moving a cloth cutting knife up and down two or more times during formation of a buttonhole darning seam, characterized by knife upward-and-downward movement timing decide means included in a CPU or the like for deciding the timing of the upward-and-downward movement of the cloth cutting knife in accordance with the length of the buttonhole, knife upward-and-downward movement timing interval judge means included in a CPU or the like for judging an interval between the upward-and-downward movement timings decided by the knife upward-and-downward movement timing decide means, and sewing machine drive speed decide means included in a CPU or the like for deciding the drive speed of the sewing machine in accordance with the gap judged by the knife upward-and-downward movement timing interval judge means.

Here, the knife upward-and-downward movement timing decide means, knife upward-and-downward movement timing interval judge means, and sewing machine drive speed decide means are respectively included in a CPU or the like.

In the sixteenth aspect, with use of this invention, in the two or more times of upward-and-downward movement of the cloth cutting knife, the sewing machine drive speeds can be respectively controlled in a proper manner, which makes it possible to form the buttonhole in a good condition.

• Fig. 1 is a perspective view of the appearance of a buttonhole darning sewing machine to which the present invention is applied;
• Fig. 2 is a schematic perspective view of a first embodiment of a buttonhole darning sewing machine according to the invention, showing the internal mechanism thereof;
• Fig. 3 is also a schematic perspective view, when viewed from the opposite side of Fig. 2, of the first embodiment of a buttonhole darning sewing machine according to the invention, showing the internal mechanism thereof;
• Fig. 4 is a front view of a needle swing mechanism shown in Fig. 3, when viewed from the needle side;
• Fig. 5 is a typical view of the needle swing mechanism shown in Fig. 4, explaining the operation thereof;
• Fig. 6 (a) is a view of the needle swing mechanism, showing a state thereof in which the cam top portion of a needle swing cam is situated on the base line side, and Fig. 6 (b) is a view of the needle swing mechanism, showing a state thereof in which the cam top portion of a needle swing cam is situated on the cam swing width side;
• Fig. 7 shows the change of the base line position to be executed by the needle swing mechanism;
• Fig. 8 shows the change of the swing width position to be executed by the needle swing mechanism;
• Fig. 9 is a table, showing the number of pulses output by a base line pulse motor and a swing width pulse motor;
• Fig. 10 is a graphical representation of the characteristics of the pulse number - base line movement amount;
• Fig. 11 is a graphical representation of the characteristics of the pulse number - needle swing amount;
• Fig. 12 (a) shows the names of the respective portions of a buttonhole darning portion, Fig. 12 (b) shows the right-handed pattern thereof, and Fig. 12 (c) shows the right-handed pattern thereof;
• Fig. 13 is a perspective view of a cloth cutting knife drive mechanism;
• Fig. 14 (a) shows a state in which a cloth is cut once by the first downward movement of the cloth cutting knife, Fig. 14 (b) shows the cloth feed direction, and Fig. 14 (c) shows the second downward movement of the cloth cutting knife;
• Fig. 15 is a section view of the structure of a tension block which can be variably controlled by a voice coil motor;
• Figs. 16 (a) and 16 (b) show the operation of stitches aided by the tension block having an active tension function through a voice coil motor; in particular, Fig. 16 (a) shows sewing start portion including a first stitch, and Fig. 16 (b) shows a lock stitch sewing portion including the last stitch;
• Fig. 17 is a schematic perspective view of a second embodiment of a buttonhole darning sewing machine according to the invention, showing the internal mechanism thereof similar to Fig. 2;
• Fig. 18 is a schematic perspective view of a third embodiment of a buttonhole darning sewing machine according to the invention, showing the internal mechanism thereof similar to Fig. 2;
• Fig. 19 is a schematic perspective view of a fourth embodiment of a buttonhole darning sewing machine according to the invention, showing the internal mechanism thereof similar to Fig. 2;
• Fig. 20 is a schematic perspective view of a fifth embodiment of a buttonhole darning sewing machine according to the invention, that is, as another embodiment of the needle swing mechanism, showing the internal mechanism thereof similar to Fig. 3;
• Fig. 21 is a schematic perspective view of a sixth embodiment of a buttonhole darning sewing machine according to the invention, showing the internal mechanism thereof similar to Fig. 3;
• Fig. 22 shows a seventh embodiment of a buttonhole darning sewing machine according to the invention; in particular, Fig. 22 is a perspective view of a drive system which moves the cloth cutting knife upward and downward using a mechanical drive mechanism;
• Fig. 23 shows an eighth embodiment of a buttonhole darning sewing machine according to the invention; in particular, Fig. 23 is a perspective view of a cloth cutting knife drive system;
• Fig. 24 is an exploded perspective view of a general example of a cloth cutting knife mounting structure;
• Fig. 25 shows a ninth embodiment of a buttonhole darning sewing machine according to the invention; in particular, Fig. 25 is an exploded perspective view of the structure of a judgment portion;
• Fig. 26 is an exploded perspective view of the structure of a judgment portion, in which the structure shown in Fig. 25 is modified in part;
• Fig. 27 (a) is a view of an ordinary cloth cutting knife, Figs. 27 (b) and (c) are respectively views of a tenth embodiment according to the invention; in more particular, Fig. 27 (b) is a view of a cloth cutting knife including an escape hole, and Fig. 27 (c) is a view of a cloth cutting knife including a cut-away portion;
• Figs. 28 (a) and 28 (b) show a judgment portion mounting thereon a judging switch including a push switch portion corresponding to an escape hole; in particular, Fig. 28 (a) is a side view thereof, and Fig. 28 (b) is a front view thereof;
• Figs. 29 (a) and 29 (b) show a judgment portion mounting thereon a judging switch including a push switch portion corresponding to a cut-away hole; in particular, Fig. 29 (a) is a side view thereof, and Fig. 29 (b) is a front view thereof;
• Fig. 30 is a perspective view of a cloth presser and a cloth cutting knife, showing the relation between them;
• Fig. 31 shows an eleventh embodiment according to the invention; in particular, Fig. 31 is a perspective view thereof in which a judgment sensor is provided on the leading end portion side of a cloth hold arm;
• Fig. 32 is a perspective view of a pair of upper thread scissors and a drive mechanism therefor;
• Fig. 33 is a plan view of a pair of upper thread scissors and a cam, showing the relation between them;
• Fig. 34 is a plan view of the upper thread scissors, showing a state thereof in which it is moved in the same direction as the cloth feed direction while holding an upper thread;
• Fig. 35 is a block diagram of a control block used in a buttonhole darning sewing machine;
• Fig. 36 is a front view of an operation panel;
• Fig. 37 is a general flow chart according to which control is executed by the control block shown in Fig. 35;
• Fig. 38 is a flow chart of a subroutine for an operation panel setting processing (Step S1);
• Fig. 39 is a table which shows items to be set;
• Fig. 40 shows conditions set for a buttonhole darning portion;
• Fig. 41 is a flow chart of a subroutine for a pattern change processing (Step S106);
• Fig. 42 is a flow chart of a subroutine for a parameter change processing (Step S108);
• Fig. 43 is a flow chart of a subroutine for a speed change processing (Step S110);
• Fig. 44 is a flow chart of a subroutine for a thread insertion processing (Step S112);
• Figs. 45 (a) and 45 (b) show the relation between a needle and a cloth cutting knife situated in the rear of the needle in the thread insertion operation; in particular, Fig. 45 (a) is a side view thereof, and Fig 45 (b) is a front view thereof, showing a state in which the needle is swung to the right up to the maximum position with respect to the cloth cutting knife;
• Fig. 46 shows the last needle which is dropped to the left side with respect to the cloth cutting knife;
• Fig. 47 is a flow chart of a subroutine for a tension hook matching processing (Step S114);
• Fig. 48 (a) is a front view of a state in which the needle is stopped on the right of the cloth cutting knife, Fig. 48 (b) is a plan view of a state in which the needle is moved to the needle hole center of the cloth presser, Fig. 48 (c) is a front view of a state in which the needle is moved downward, and Fig. 48 (d) is a front view of a state in which the needle bar is moved downward from its stop position;
• Fig. 49 is a flow chart of a subroutine for a sewing data creation processing (Step S3);
• Fig. 50 is a flow chart of a subroutine for an enlargement/reduction processing (Step S31);
• Figs. 51 (a) and 51 (b) are explanatory views of an enlargement/reduction processing to be executed in a buttonhole darning operation; in particular, Fig. 51 (a) is a view of a reference point used in the enlargement/reduction processing, and Fig. 51 (b) is a view of the designations of the respective portions of the buttonhole darning operation;
• Fig. 52 is a flow chart of a subroutine for a presser/knife size check processing (Step S32);
• Fig. 53 is a flow chart of a subroutine for a pattern operation processing (Step S35);
• Fig. 54 is a view of a right-handed sewing sequence;
• Fig. 55 is a table of sewing data operation results;
• Fig. 56 is a flow chart of a subroutine for a sewing start position operation processing (Step S351);
• Fig. 57 shows how to decide a knife drop center position;
• Fig. 58 is a flow chart of a subroutine for a left parallel portion operation processing (Step S352);
• Fig. 59 is a flow chart of a subroutine for a first lock stitch portion operation processing (Step S353);
• Fig. 60 is a view of an analysis of the details of the first lock stitch portion up to the middle thereof;
• Fig. 61 is a flow chart of a subroutine for a right parallel portion operation processing (Step S354);
• Fig. 62 is a flow chart of a subroutine for a second lock stitch portion operation processing (Step S355);
• Fig. 63 is a flow chart of a subroutine for a sewing end operation processing (Step S356);
• Fig. 64 is a flow chart of a subroutine for a knife drive timing operation processing (Step S36);
• Fig. 65 is a table of the stitch number which is the number of times of the knife drive operations corresponding to the number of times of knife drivings;
• Fig. 66 is a table of conditions used in a buttonhole darning portion;
• Fig. 67 is a perspective view of a structure including a feed sensor and a knife drop switch in order to time the operation of a cloth cutting knife from the Y feed;
• Fig. 68 (a) is a perspective view of a state after a cloth is cut by the first upward-and-downward movement of the cloth cutting knife, and Fig. 68 (b) is a perspective view of a state after the remaining portion of the cloth is cut by the second upward-and-downward movement of the cloth cutting knife;
• Figs. 69 (a) and 69 (b) are explanatory views of the two-times of the upward-and-downward movement of a cloth cutting knife; in particular, Fig. 68 (a) is a view of a state in which first and second knife drops are overlapped on each other, and Fig. 68 (b) is a view of a state in which the first and second knife drops are greatly overlapped;
• Fig. 70 is a view of the change of a knife drop timing;
• Fig. 71 is a view of the movement of the whole knife drop position;
• Fig. 72 is a flow chart of a subroutine for a machine origin retrieval processing (Step S5);
• Fig. 73 is a flow chart of a subroutine for a sewing operation processing (Step S15);
• Fig. 74 is a flow chart of a subroutine for a TG interrupt processing (Step S160);
• Fig. 75 is a view of the change of a needle upper position interrupt processing (S162);
• Fig. 76 is a view of a knife drive processing (Step S1625);
• Fig. 77 is a flow chart of a subroutine for a cloth cutting knife downward-movement processing (Step S16264);
• Fig. 78 is a flow chart of a subroutine for a feed reference interrupt processing (Step S164);
• Fig. 79 is a flow chart of a subroutine for a cloth cutting knife counter interrupt processing (Step S165);
• Fig. 80 is a flow chart of a subroutine for a cloth cutting knife drive check processing (Step S1654);
• Fig. 81 shows a modification of a control system; in particular, Fig. 81 is a general flow chart obtained by modifying the general flow shown in Fig. 37 in part;
• Fig. 82 shows conditions used in a buttonhole darning operation;
• Fig. 83 is a flow chart of a subroutine for a sewing processing (Step S22);
• Fig. 84 is a flow chart of a subroutine for a sewing processing (1) (Step S222);
• Fig. 85 is a flow chart of a subroutine for a sewing processing (3) (Step S225);
• Figs. 86 (a) to 86 (c) show a difference between a front knife cutting operation and a middle knife cutting operation; in particular, Fig. 86 (a) is view of the front knife cutting operation to be executed prior to sewing of buttonhole darning stitches, Fig. 86 (b) is a view of a rear knife cutting operation to be executed after completion of sewing of buttonhole darning stitches, and Fig. 86 (c) is view of a middle knife cutting operation to be executed while the buttonhole darning stitches are being sewn;
• Fig. 87 (a) is a side view to show how upper and lower cloths are cut in the front knife cutting operation, Fig. 87 (b) is a side view of hemstitching obtained when a needle is passed through a buttonhole to thereby connect together lower and upper threads, and Fig. 87 (c) is a side view to show that no material thread (weaving yarn) of the cloth is left in the buttonhole;
• Fig. 88 is a side view of the state of buttonhole darning stitches formed in the rear and middle knife cutting operations;
• Fig. 89 is a flow chart of a subroutine for a left-handed pattern operation processing (Step S38);
• Fig. 90 is a view of a left-handed sewing sequence;
• Fig. 91 is a table of sewing data operation results;
• Figs. 92 (a) and 92 (b) are explanatory views of the left- and right-handed operations to be executed by a needle swing mechanism; in particular, Fig. 92 (a) is a front view to show the movement of a base line, and Fig. 92 (b) is a side view thereof;
• Figs. 93 (a) to 93 (c), similarly to Figs. 92 (a) and 92 (b), are explanatory views of the left- and right-handed operations to be executed by a needle swing mechanism; in particular, Fig. 93 (a) is a front view to show the change of a needle swing amount, Fig. 93 (b) is a left side view thereof, and Fig. 93 (c) is a right side view thereof;
• Fig. 94 is a view of conditions used in a buttonhole darning operation;
• Fig. 95 is a table to show items to be set;
• Fig. 96 is a flow chart of a subroutine for a sewing start position operation processing (Step S381);
• Fig. 97 is a flow chart of a subroutine for a right parallel portion operation processing (Step S382);
• Fig. 98 is a flow chart of a subroutine for a first lock stitch portion operation processing (Step S383);
• Fig. 99 is a flow chart of a subroutine for a second lock stitch portion operation processing (Step S385);
• Fig. 100 is a flow chart of a subroutine for a sewing end operation processing (Step S386);
• Fig. 101 is a flow chart of an additional processing embodiment 1 of a subroutine for a tension hook matching mode processing (Step S114);
• Fig. 102, similarly to Fig. 101, is a flow chart of an additional processing embodiment 2 of a subroutine for a tension hook matching mode processing (Step S114);
• Fig. 103 is a flow chart of the subroutine for a sewing main shaft angle matching processing (Step S1152);
• Fig. 104 is a flow chart of a modification of the subroutine for a sewing main shaft angle matching processing (Step S1152);
• Fig. 105 is a circuit diagram, showing the arrangement of a relay used to cut off power;
• Fig. 106 is a circuit diagram, showing the arrangement of a modification of the relay used to cut off power;
• Fig. 107 is a flow chart of a first additional processing embodiment 1 of the subroutine for the thread insertion mode processing shown in Fig. 44 (Step S112);
• Fig. 108, similarly to Fig. 107, is a flow chart of a second additional processing embodiment 1 of the subroutine for the thread insertion mode processing shown in Fig. 44 (Step S112);
• Fig. 109 is a flow chart of an additional processing embodiment of the subroutine for the knife drive timing operation processing (Step S36);
• Fig. 110 is a pserspective view of an embodiment in which a needle position sensor is provided;
• Fig. 111 (A) is an operation timing chart of a thread cutting mechanism according to the invention, and Fig. 107 (B) is an operation timing chart of another embodiment of the thread cutting mechanism according to the invention; and,
• Fig. 112 is an explanatory view of the movement position of a pair of upper thread scissors employed in another embodiment according to the invention.

At first, Fig. 1 is a perspective view of the appearance of a buttonhole darning sewing machine which is a first embodiment according to the invention. Also, Fig. 2 is a perspective view of the outline of the internal mechanism of the first embodiment, and Fig. 3 is a perspective view of the above internal mechanism when it is viewed from the opposite side of Fig. 2.

In Figs. 1 to 3, reference character 1 designates a sewing machine frame, 5 a sewing machine motor, 6 an upper shaft, 7 crank mechanism, 8 a needle bar, 9 a needle, 10 a vertical shaft, 11 a lower shaft, 12 a hook, 13 a bobbin case, 14 a cloth hold plate, 15 a cloth presser (a frame-shaped clamp body), 16 a cloth cutting knife (a vertically moving knife), 17 a balance, 18 a needle bar swing base, 19 a tension block, 20 a feed motor (electrically driving means: pulse motor), 21 a feed mechanism (connecting means), 30 an air cylinder unit for a cloth cutting knife, 31 a knife mounting plate, 40 a base line motor, 41 a swing width motor, 42 a needle swing mechanism, and 60 a voice coil motor, respectively.

As shown in Figs. 1 to 3, the sewing machine frame 1 comprises a bed 2 including a flat bed surface on the upper surface thereof, a vertical body portion 3 erected on the one end portion side of the bed 2, and an arm 4 disposed on the vertical body portion 3 and extending substantially in parallel to the bed 2; and, the sewing machine frame 1 has a substantially U-like shape when it is viewed from the flank thereof.

In the above-mentioned sewing machine frame 1, a sewing machine motor 5 is provided in the end portion thereof on the vertical body portion 3 side, the upper shaft 6 which can be rotated when it is driven by the sewing machine motor 5 is disposed within the arm 4, the needle bar 8 is connected through the crank mechanism 7 to the leading end portion of the upper shaft 6, and the needle 9 is mounted on the lower portion of the needle bar 8.

Also, the vertical shaft 10 is disposed within the vertical body portion 3, the lower shaft 11 is disposed within the bed 2, and the bobbin case 13 is mounted on the tension hook 12 which is disposed in the leading end portion of the lower shaft 11. By the way, the upper end portion of the vertical shaft 10 is connected to the upper shaft 6 through bevel gears 6a and 10a, whereas the lower end portion of the vertical shaft 10 is connected to the lower shaft 11 through bevel gears 10b and 11a.

Further, on the bed 2, there is disposed the cloth hold plate 14 which can be moved, and, above the cloth hold plate 14, there are disposed the cloth presser 15 formed of a frame-shaped clamp body and the cloth cutting knife 16 which is a vertically moving knife. By the way, in the crank mechanism 7, there is incorporated the balance 17 which projects externally from the side surface of the leading end portion of the arm 4.

Also, the needle bar 8 is incorporated in the needle bar swing base 18 in such a manner that it can be freely slided in the vertical direction. The needle bar swing base 18 is structured in such a manner that the upper end portion thereof is free to swing with a swing fulcrum shaft 18a parallel to the upper shaft 6 as the fulcrum thereof. And, the tension block 19 is arranged in the lower portion of the side surface of the leading end portion of the arm 4, while the tension block 19 is structured such that the tension thereof can be variably controlled by the voice coil motor 60.

In the interior portion of the vertical body portion 3, there is disposed the feed motor 20 which is used as electrically driving means for driving the cloth hold plate 14 and cloth presser 15 electrically; the feed motor 20 is a pulse motor which has an axis extending in the vertical direction; and, there is structured the feed mechanism 21 which extends from the output shaft of the feed motor 20 to the cloth hold plate 14 and cloth presser 15.

Also, on the leading end portion of the arm 4, there is mounted the cloth cutting knife air cylinder unit 30 which serves as electrically driving means for the cutting operation of the cutting knife, while the knife mounting plate 31, which can be moved upward and downward when it is driven by the cloth cutting knife air cylinder unit 30, is so disposed as to extend in the vertical direction within the arm 4. The cloth cutting knife 16 is mounted on the lower end portion of the knife mounting plate 31 by a set screw 32, while the lower end portion of the knife mounting plate 31 is projected downward from the arm 4.

By the way, as shown in Fig. 13, to the knife mounting plate 31, there is connected a return spring 33 for lifting and returning the knife mounting plate 31 to its original position; and, on the flank side of the knife mounting plate 31, there are arranged cloth cutting upper and lower position detect sensors 34a and 34b of a close approach type which are respectively used to detect the portion to be detected 31a of the knife mounting plate 31.

Further, within the vertical body portion 3, there are disposed the base line motor 40 for deciding the base line position of the needle bar swing base 18 and the swing width motor 41 for deciding the swing width thereof. Both of the base line motor 40 and swing width motor 41 are pulse motors each of which has an axis extending horizontally in parallel to the upper shaft 6, while there is structured the needle swing mechanism 42 which extends from the respective output shafts of the base line motor 40 and swing width motor 41 to the needle bar swing base 18.

Now, the feed mechanism 21, as shown in Fig. 2, comprises a feed shaft 22 with the axis thereof extending in the horizontal direction, a bracket 23 for the cloth hold plate 14, a cloth hold arm 24 for holding the cloth presser 15, and the like. In this manner, there is structured connecting means which extends from the feed motor 22 to the cloth hold arm 24.

That is, in the vertical body portion 3, there is incorporated the feed shaft 22 including a rack 22a in meshing engagement with a pinion 20a provided on the output shaft of the feed motor 20 and, to the middle portion of the feed shaft 22 that is projected from the vertical body portion 3 and is situated below the arm 4, there is fixed the upper end portion of the bracket 23 which supports the cloth hold plate 14 in the lower end portion thereof. The base end portion of the cloth hold arm 24 including a mounting piece 25, which supports the cloth presser 15 in the leading end portion thereof, is connected to the side surface of the lower portion of the bracket 23 in such a manner that it is free to swing in the vertical direction with a pin 24a as the fulcrum thereof.

By the way, although not shown, there are provided an actuator (an air cylinder, a solenoid, or the like) for lifting the cloth hold arm 24, a return spring for lowering the hold arm 24 down to the initial position. However, the vertical movement of the cloth hold arm 24 can also be carried out by means of operation of a pedal.

Also, there is provided an origin position detect sensor 26 of a close approach type which is used to detect an origin position corresponding to the position of the leading end of the knife in accordance with the position of the feed shaft 22.

By means of the above-structured feed mechanism 21, when the feed motor 20 comprising a pulse motor is driven, then the cloth hold plate 14 and cloth presser 15 are moved integrally on the bed 2 through the feed shaft 22, which can be moved back and forth through the meshing engagement between the pinion 20a and rack 22a, as well as through the bracket 23 and cloth hold arm 24.

The above-mentioned means is means which is employed in the present embodiment for moving the cloth electrically.

That is, in a buttonhole darning sewing machine, since the feed motor 20 comprising a pulse motor for driving the cloth hold arm 24 through the feed mechanism 21 is stored within the vertical body portion 3 of the sewing machine frame 1 in the above-mentioned manner, the space in the vertical body portion 3 can be used effectively and, at the same time, the number of parts to be mounted on the outside of the sewing machine frame 1 can be reduced so that the appearance of the sewing machine frame 1 can be made neat and simple.

Also, since the feed motor 20 for driving the cloth hold arm 24 is stored within the vertical body portion 3, not only there can be provided a sound insulation effect, but also the handling of the cloth can be improved, which in turn can solve a problem that the cloth can be soiled as in the case where a motor is mounted on the outside of a sewing machine frame.

Further, since the pinion 20a of the output shaft of the pulse motor (feed motor) 20 with the axis thereof extending in the vertical direction is meshingly engaged with the rack 22a of the feed shaft 22 with the axis thereof extending in the horizontal direction and also since the cloth hold arm 24 is fixed to the feed shaft 22, the feed shaft 22 can be driven or moved linearly in the horizontal direction by the vertically extending pulse motor (feed motor) 20 through the rack 20a and pinion 22a, thereby being able to move the cloth hold arm 24 in a direction in which the cloth hold arm 24 approaches and parts apart from the vertical body portion 3.

By the way, because the base line motor 40 and swing width motor 41 respectively comprising pulse motors are both stored within the vertical body portion 3 in such a manner that their axes are so arranged as to extend in parallel to the upper surface of the bed 2, similarly to the feed motor 20, the space of the interior portion of the vertical body portion 3 can be used effectively and, at the same time, the number of parts to be mounted on the outside of the sewing machine frame 1 can be reduced so that the appearance of the sewing machine frame 1 can be made neat and simple.

Next, the needle swing mechanism 42, as shown in Figs. 3 to 5, comprises a base line arm 43, a base line lever 44, a connecting link 45, a needle swing cam lever 46, a needle swing lever 47, a connecting shaft 48, a needle swing arm 49, a needle swing cam 54, a swing width arm 55, a swing width lever 56, and the like.

That is, within the vertical body portion 3, a sector gear 43b, which is provided in the lower end portion of the base line arm 43 with a support shaft 43a supported horizontally in the sewing machine frame as the fulcrum of the middle portion thereof, is engaged in mesh with a pinion 40a provided on the output shaft of the base line motor 40, and the end portion of the forked base line lever 44 is swingably connected to the forked portion of the upper portion of the base line arm 43 by a horizontal pin 44a. Also, one end portion of the connecting link 45 is swingably connected into the forked portion of the base line lever 44 by a horizontal pin 44b, while the needle swing cam lever 46 is swingably connected to the other end portion of the connecting link 45 by a horizontal pin 45a.

Further, the leading end portion of the needle swing lever 47 is swingably connected to the lower end portion of the needle swing cam lever 46 by a horizontal pin 46a, while the base end portion of needle swing lever 47 is fixed to the base end portion of the connecting shaft 48 which is disposed in parallel to the upper shaft 6 within the arm 4. And, the base end portion of the needle swing arm 49 is fixed to the leading end portion of the connecting shaft 48, while the needle bar swing base 18 is swingably connected to the leading end portion of the needle swing arm 49 through a square piece (not shown) or the like.

Here, the needle swing cam lever 46 is so formed as to have an upwardly opened U-shaped engaging recessed portion 46b, while the needle swing cam 54 comprising an eccentric cam is in engagement with the engaging recessed portion 46b.

That is, the needle swing cam 54 is mounted on a counter shaft 53 to which the rotation of the upper shaft 6 can be transmitted at a reduction ratio of 1/2 through reduction gears 51 and 52.

Further, within the vertical body portion 3, a sector gear 55b, which is provided in the lower end portion of the swing arm 55 with a support shaft 55a supported horizontally in the sewing machine frame as the fulcrum of the middle portion thereof, is engaged in mesh with a pinion 41a provided on the output shaft of the swing width motor 41, and the end portion of the swing width lever 56 is swingably connected to the forked portion of the upper portion of the swing width arm 55 by a horizontal pin 56a. The other end portion of the swing width lever 56 is swingably connected to the connecting link 45 through the horizontal pin 44b.

By the way, on the flank portion of the sector gear 43b of the base line arm 43, there is disposed a base line origin detect sensor 57 which is formed of a magnetic sensor serving as base line position detect means and, on the one end portion side of the sector gear 43b, there is disposed a magnet 43c for detection of the base line. Similarly, in the neighborhood of the sector gear 55b of the swing width arm 55, there is disposed a swing width origin detect sensor 58 which is formed of a magnetic sensor serving as needle swing width detect means and, on one end portion side of the sector gear 55b, there is arranged a magnet 55c which is used to detect the needle swing width.

Also, on one side surface of the reduction gear 52 located on the counter shaft 53 side, there is disposed a needle swing right and left position detect sensor 59 (base line side/needle swing side detect means) which is formed of a magnetic sensor, while the reduction gear 52 includes a magnet 52a which is used to detect the right and left position.

By the way, the reduction gear 52 makes one rotation while the reduction gear 51 on the upper shaft 6 makes two rotations, that is, the reduction gear 52 rotates once while the needle 9 makes its up-and-down motion twice. The needle swing right and left position detect sensor 59, in a rotation phase where the needle 9 is situated at the upper stop position and is swung toward the base line side, is disposed opposed to the magnet 52a.

With use of the above-structured needle swing mechanism 42, swing movements are transmitted to the needle bar swing base 18 by means of the driving operations of the base line motor 40 and swing width motor 41, which are both formed of pulse motors serving as drive means, through the base line arm 43 to the base line lever 44, or through the swing width arm 55 to the swing width lever 56, and, after then, through the connecting link 45, needle swing cam lever 46, needle swing lever 47, needle swing arm 49 and needle swing cam 54, so that the base line and swing width can be changed with the swing fulcrum shaft 18a provided in the upper portion of the needle bar swing base 18 as the fulcrum thereof.

That is, as shown in Fig. 4 and as shown typically in Fig. 5, with regard to the base line, due to the driving operation of the base line motor 40 comprising a pulse motor, the swing movement is transmitted to the needle bar swing base 18 through the base line arm 43, base line lever 44, connecting link 45, needle swing cam lever 46, needle swing lever 47, needle swing arm 49 and needle swing cam 54, thereby causing the needle bar swing base 18 to swing with the swing fulcrum shaft 18a provided in the upper portion of the needle bar swing base 18 as the fulcrum thereof, so that the base line can be changed. This is the base line change mechanism.

Also, with regard to the swing width, due to the driving operation of the swing width motor 41 comprising a pulse motor, the swing movement is transmitted to the needle bar swing base 18 through the swing width arm 55, swing width lever 56, connecting link 45, needle swing cam lever 46, needle swing lever 47, needle swing arm 49 and needle swing cam 54, thereby causing the needle bar swing base 18 to swing with the swing fulcrum shaft 18a provided in the upper portion of the needle bar swing base 18 as the fulcrum thereof, so that the swing width can be changed. This is the needle swing width change mechanism.

Here, the needle swing mechanism 42 is a mechanism which swings (increases) the swing width to the left with the base line position as a reference and, in the needle swing mechanism 42, as shown in Fig. 6 (a), when the cam top portion of the needle swing cam 54 is situated on the base line side (in Fig. 6 (a), on the right side), the dropping of the needle is decided in accordance with the position of the base line arm 43.

Also, as shown in Fig. 6 (b), when the cam top portion of the needle swing cam 54 is situated on the cam swing width side (in Fig. 6 (a), on the left side), the dropping of the needle is decided in accordance with the amount of the swing width with respect to the base line position.

And, the movement of the base line position, as shown in Fig. 7, can be executed by the rotation of the base line arm 43.

Also, the change of the swing width, as shown in Fig. 8, can be executed by the rotation of the swing width arm 55 through the base line lever 44.

Now, when sewing, if the sewing machine motor 5 is driven, then the upper shaft 6 is rotated, the rotational movement of the upper shaft 6 is transmitted to the needle swing cam 54 provided in the counter shaft 53 through the reduction gears 51 and 52 so that the needle swing cam 54 is rotated at the reduction ratio of 1/2; the needle swing cam lever 46, which includes the cam engaging recessed portion 46b in engagement with the needle swing cam 54, is thereby caused to swing reciprocatingly; and, the reciprocating swing motion of the needle swing cam lever 46 is then transmitted to the needle bar swing base 18 through the needle swing lever 47, connecting shaft 48, needle swing arm 49 and needle swing cam 54.

As a result of this, based on the above-mentioned changes of the base line and swing width, the needle bar swing base 18 is reciprocatingly swung with the swing fulcrum shaft 18a on the upper end portion of the needle bar swing base 18 as the fulcrum thereof, thereby forming the stitches of the parallel portion (side sewing portion) and lock stitch portion (lock stitch sewing portion) in the buttonhole darning operation.

And, in the above mechanism which moves the base line in correspondence to the angle of the base line arm 43 functioning as a base line adjust arm, the base line arm 43 swings about a single shaft, with the result that the base line movement amount provides such amount as shown by a solid line in Fig. 10 in correspondence to the angles of the base line arm 43 depending on the generation of the number of the output pulses of the base line motor (pulse motor) 40.

Also, similarly, there is obtained such needle swing amount as shown by a solid line in Fig. 11 in correspondence to the angles of the swing width arm 55 which functions as a swing width adjust arm depending on the generation of the number of the output pulses of the swing width motor 41 comprising a pulse motor.

On the contrary, with use of the above-mentioned needle swing mechanism 42, the output pulse numbers, k₁, k₂,k_n-1, k_n with respect to the base line motor 40, which are shown in Fig. 9, are the pulse numbers that are so corrected as to approach an ideal line (a broken line shown in Fig. 10) and, similarly, the output pulse numbers, h₁, h₂, h_n-1, h_n with respect to the swing width motor 41 are the pulse numbers that are so corrected as to approach an ideal line (a broken line shown in Fig. 11).

Next, Fig. 12 (a) shows the names of the respective portions of the buttonhole darning and, as shown in Fig. 12 (a), the left and right sides of the buttonhole are respectively a left parallel portion (a left side sewing portion) and a right parallel portion (a right side sewing portion), while the rear and front sides of the buttonhole are respectively a first lock stitch portion (a rear lock stitch sewing portion) and a second lock stitch portion (a front lock stitch sewing portion).

The buttonhole darning can be executed selectively in two ways by the above-structured buttonhole darning sewing machine, that is, one is a right-handed stitching, and the other is a left-handed stitching. In particular, the right-handed stitching, as shown in Fig. 12 (b), starts at the left side of the second lock stitch portion (the front lock stitch sewing portion), after then, the left parallel portion (the left side sewing portion), first lock stitch portion (the rear lock stitch sewing portion), and right parallel portion (the left side sewing portion) are respectively executed in this order, and finally the right-handed stitching returns to the second lock stitch portion (the front lock stitch sewing portion). On the other hand, the left-handed stitching, as shown in Fig. 12 (c), starts at the right side of the second lock stitch portion (the front lock stitch sewing portion), after then, the right parallel portion (the right side sewing portion), first lock stitch portion (the rear lock stitch sewing portion), and left parallel portion (the left side sewing portion) are respectively executed in this order, and finally the left-handed stitching returns to the second lock stitch portion (the front lock stitch sewing portion).

Also, in the buttonhole darning sewing machine according to the present embodiment, the cloth cutting knife 16 is moved up and down a plurality of times during the buttonhole darning operation by driving the cloth cutting knife air cylinder unit 30 shown in Fig. 13, thereby forming a buttonhole.

That is, for example, as shown in Fig. 4 (a), the cloth is cut once by the first downward motion of the cloth cutting knife 16, next, as shown in Fig. 4 (b), the cloth is fed in a direction of an arrow shown in Fig. 4 and, after then, the cloth cutting knife 16 is moved downward again, thereby forming a buttonhole of a predetermined length.

Since the cloth cutting knife 16 having a cutting edge length shorter than the length of the side sewing portion of the buttonhole darning stitches is moved upward and downward a plurality of times to thereby form a buttonhole having a length corresponding to the length of the side sewing portion, a buttonhole having an arbitrary length can be formed by a single kind of cloth cutting knife 16.

Therefore, even if the length of a buttonhole varies, there is no need to replace the cloth cutting knife or it is not necessary to prepare several kinds of cloth cutting knives which correspond in number to the lengths of buttonholes.

Now, Fig. 15 is a partial section view of the structure of the tension block 19 the tension of which is variably controlled by the voice coil motor 60, showing its assembled state.

That is, a plunger 61, which is provided in a voice coil motor 60 having an excellent linear characteristic, is butted against one end portion of a lever 62 including a pin 62a provided in the middle portion thereof and serving as the fulcrum thereof, a bearing case 64 and a hollow shaft 65 are assembled onto an operation shaft 63 in contact with the other end portion of the lever 62, and a pair of tension dishes 66 and 67 are slidably assembled onto the hollow shaft 65, thereby forming the tension block 19.

Since the tension block 19 is structured in this manner, a tension to be given to an upper thread can be changed by changing pressures to be applied to the pair of tension dishes 66 and 67 on the hollow shaft 65 through the operation shaft 63 according to the pressure (driving force) of the plunger 61 of the voice coil motor 60.

In more particular, the tension block 19 provided in the arm 4 is composed of a pair of inner and outer dishes 66 and 67; and, according to the present embodiment, a fixed dish 67 comprising an outer dish is assembled on the flange side of the leading end portion of the hollow shaft 65, and a movable dish 66, which consists of an inner dish and is disposed opposed to the fixed dish 67, is slidably assembled on the hollow shaft 65.

And, in the interior portion of the hollow shaft 65, there is disposed a contact piece 66a which can be pressed by the leading end portion of the operation shaft 63 when it is slidably inserted into the interior portion of the hollow shaft 65, while the contact piece 66a is formed integrally with the movable dish 66.

By the way, on the contrary to the present embodiment, the inner dish 66 may be used as a fixed dish and the outer dish 67 may be used as a movable dish. In this case, the contact piece may be formed integrally with the outer dish 67 serving as a movable dish, and the leading end portion of the operation shaft 63 may be connected to the contact piece through engagement or the like so that the contact piece can be pulled by the operation shaft 63.

In the above-structured tension block 19, the hollow shaft 65 is rotatably carried by the bearing case 64, while the bearing case 64 is inserted into and fixed to an assembling hole formed in the arm 4.

And, the operation shaft 63, which is to be inserted into the interior portion of the hollow shaft 65 of the tension block 19, can be driven by a voice coil motor 60 serving as a linear d.c. motor comprising a low inertia motor.

The present voice coil motor 60 comprises a cylindrical-shaped yoke 601 making a magnetic circuit, an outer pole 602 comprising a permanent magnet provided in the inner periphery of the end portion of the yoke 601, a center pole 603 comprising an iron core formed integrally in the central portion of the cylindrical yoke 601, and a cylindrical-shaped movable coil 604 interposed between the center pole 603 and outer pole 602.

Also, the movable coil 604 is composed of a compensation steel pipe 605 and a coil 606 provided on the outer periphery of the compensation steel pipe 605, and the movable coil 604 further includes the plunger 61 which is integrally provided in the central portion of a coil head thereof located in the leading end portion thereof.

In the above-structured voice coil motor 60, a magnetic field is applied to the movable coil 604 from the outer pole (permanent magnet) 602 disposed on the outer periphery of the center pole (iron core) 603 of the magnetic circuit, a control current is supplied from a control current supply circuit (CC) to the movable coil (coil 606) 604 under such magnetic field to thereby generate a thrust (or a sucking force), which causes the plunger 61 provided in the coil head to advance (or retreat), so that the operation shaft 63 is moved forward (or backward) within the hollow shaft 65 through the lever 62.

The above-structured voice coil motor 60 provides several characteristics as follows: that is, it is small in inductance and quick in response; it is small in inertia and quick in response because it includes only the movable coil 604 as a moving part; the sucking force (or thrust) of the movable coil 604 is constant regardless of distance; and, a sucking force (or thrust) which is linear and in proportion to a current can be taken out.

Since the voice coil motor 60 has the above-mentioned characteristics, if the operation shaft 63 is driven to move forward (or backward) within the hollow shaft 65 through the lever 62 by the plunger 61 formed integrally with the movable coil 604, then the movable dish 66 can be pushed in the axial direction thereof through the contact piece 66a to thereby change the pressure applied between the movable dish 66 and fixed dish 67, so that a gripping force to be applied to a thread passing through the tension block 19 can be changed. That is, the voice coil motor 60 has an active tension function with respect to the upper thread (needle thread).

As described above, since the tension block 19 has the active tension function provided by the voice coil motor 60, for example, as shown in Fig. 16 (a), in an initial sewing portion, from the first stitch to several following stitches, the tension block 19 is controlled by the voice coil motor 60 to apply a tension of almost 0 to the upper thread, thereby being able to connect the upper and lower thread to each other positively, so that the initial sewing portion can be sewn in the form of whip stitches in which the upper and lower threads balance well, which makes it possible to prevent a blooming phenomenon in which the upper thread slips off after the upper and lower threads are connected.

After then, while the tension to be applied to the upper thread by the tension block 19 is being adjusted properly under the control of the voice coil motor 60, the left parallel portion (left side sewing portion) is sewn in the form of pearl stitches (raised stitches), the first lock sewing portion (rear lock stitch sewing portion) is sewn in the form of whip stitches, the right parallel portion (the right side sewing portion) is sewn in the form of pearl stitches, and the second lock stitch portion (front lock stitch portion) is sewn in the form of whip stitches.

And, as shown in Fig. 16 (b), in the lock stitch sewing portion after the sewing operation is returned to the second lock stitch portion (front lock stitch portion), not only the tension to be applied to the upper thread by the tension block 19 under the control of the voice coil motor 60 is so increased as to be able to pull up the lower thread to the upper thread side, but also, in the cutting operation, by pulling in the lower thread, the end portion of the upper thread previously cut is pulled in behind the cloth, thereby being able to avoid a possibility that, in the last needle in which the needle swing width becomes small, any portion of the thread can be left on the upper side thereof.

Now, Fig. 32 shows upper thread scissors and a drive mechanism for driving the same, in which reference character 81 designates an arm, 82 a rotary shaft, 83 a rolling joint, 84 a lever, 85 a scissors mounting plate, 86 a fixed blade, 87 a movable blade, 88 a stepped screw, 89 a thread cutting spring (tension spring), and 90 a thread hold spring, respectively. In particular, the scissors mounting plate 85 is formed integrally with the lever 84; and, the fixed blade 86, movable blade 87 and thread hold spring 90 cooperating in forming the upper thread scissors for cutting and holding the upper thread are respectively disposed in the leading end portion of the scissors mounting plate 85.

That is, the fixed blade 86 is screwed and fixed to the leading end portion of the scissors mounting plate 85, the movable blade 87 is rotatably assembled on the upper surface of the fixed blade 86 by the stepped screw 88, and a small projection 86a provided on the fixed blade 86 faces an arc-shaped hole 87a formed in the movable blade 87. Also, the thread hold spring 90 is supported by the stepped screw 88 and small projection 86a in such a manner that it is prevented against rotation.

The fixed blade 86 includes a blade portion 86b in the leading end portion thereof and the movable blade 87 also includes in the leading end portion thereof a blade portion 87b which can be superimposed on the blade portion 86b of the fixed blade 86. Also, the movable blade 87 further includes a cam engaging portion 87c on one extension side of the arc-shaped hole 87a.

By the way, the thread cutting spring 89 is connected to the scissors mounting plate 85.

In the above-structured thread cutting mechanism, according to the present embodiment, as shown in Fig. 32, as the cloth feed direction moving means for the thread cutting means, instead of a conventional cut-off frame, there is employed a pulse motor 80, the rotary shaft 82 with the axis thereof extending in the vertical direction is rotatably assembled into the frame portion 81a of the arm 81 fixed to the output shaft 80a of the pulse motor 80, and the lever 84 is assembled to the rotary shaft 82 through the rolling joint 83 which can be freely rotated about a horizontal axis thereof.

As described above, by connecting the pulse motor 80 to the upper thread scissors (comprising the fixed blade 86, movable blade 87 and thread hold spring 90), there is formed the above-structured drive mechanism; and, the drive mechanism can be operated as follows.

That is, as shown in Figs. 119A and 120 or in Fig. 33, after completion of a sewing cycle, due to the presser lifting and thread cutting operation, the upper thread is cut by the fixed blade 86 and movable blade 87, while the thus cut end connected to the needle is held by and between the thread hold spring 90 and movable blade 87. Just after this thread cutting operation, the upper thread is moved by the pulse motor 80 to its retreat position Y_x and waits there. By the way, a return position, a separation position and a retreat position in Fig. 120 are the positions that are viewed with respect to the Y direction (cloth feed direction).

At the next sewing machine starting time, the arm 81 is rotated by a given angle in the X_cw direction by the pulse motor 80 in such a manner that the upper thread scissors can be moved by a distance Y₂ in synchronization with the operation of the cloth feed motor (see the above-mentioned feed mechanism 21), in other words, substantially at the same speed as the cloth feed speed. As a result of this, the lever 84 is swung through the rotary shaft 82 and rolling joint 83 to thereby move forward the upper thread scissors to the separation position. After the pulse motor 80 stops, the cloth hold body is continuously moved by the cloth feed motor and, therefore, similarly to the conventional structure, the upper thread releases the upper thread end.

After then, at a given timing, the upper thread scissors are moved by the pulse motor to the return position which is located laterally of the needle vertical path, while the upper thread scissors remain latched in the opened state. Also, on completion of the sewing cycle, similarly to the conventional structure, the upper thread scissors are moved due to the presser lifting and thread cutting operation in such a manner that the scissors cross the needle thread path, with the result that the upper thread scissors are able to cut and hold the thread.

In this manner, by changing the distance Y₂ (separation distance) for which the upper thread scissors are moved in synchronization with the operation of the cloth feed motor, the timing for opening the upper thread scissors (fixed blade 86 and movable blade 87) can be changed. Further, even if the cloth is moved by the cloth feed motor, the upper thread scissors move following the cloth, which makes it possible to weaken the tension of the thread in the range of the sewing start position to the scissors, thereby being able to loosen the thread.

Therefore, as shown in Fig. 34, since the upper thread scissors is moved in the same direction as the cloth feed direction to thereby be able not only to continue a state in which the upper thread scissors hold the upper thread between the movable blade 87 and thread hold spring 90, but also to weaken the tension of the upper thread, that is, loosen the upper thread.

This not only can improve the rising of the thread at the first stage of sewing of the parallel portion in the buttonhole darning operation but also allows the stitches at the first stage of sewing to be formed positively.

By the way, alternatively, as shown in Fig. 119B, the timing, at which the pulse motor moves to the retreat position may be set as the time to start the operation of the sewing machine, and the movement of the pulse motor to the separation position may be controlled by a timer.

Now, Fig. 17 shows a second embodiment of a feed mechanism and, in particular, Fig. 17, similarly to Fig. 2, is a general perspective view of the inner mechanism of the second embodiment.

In Fig. 17, like parts as in Fig. 2 are given the same designations and the description thereof is omitted. Here, description will be given below of the structures of only the parts that are different from those shown in Fig. 2.

That is, according to the second embodiment, as shown in Fig. 17, in the feed mechanism 21, the output shaft of a feed motor 20 with the axis thereof extending in the horizontal direction is connected directly with a feed shaft 22 which is formed coaxial with the feed motor 20 output shaft, there is formed a feed screw 27, and a bracket 23 is meshingly engaged with the feed screw 27 by means of a ball screw mechanism.

As described above, since the output shaft of the pulse motor (feed motor) 20 with the axis thereof extending in the horizontal direction is connected directly with the coaxial feed shaft 22 and the cloth hold arm 24 is meshingly engaged with the feed shaft 22 through the feed ball screw mechanism using the feed screw and ball, similarly to the previously described first embodiment, not only there can be obtained an effect which can be provided due to incorporation of the feed motor 20 within the vertical body portion 3, but also, while moving the feed shaft 22 in direct connection with the horizontally disposed pulse motor (feed motor) 20 linearly in the horizontal direction as the feed motor 20 is driven by the pulse motor 20, the cloth hold arm 24 can be moved in approaching and parting directions with respect to the vertical body portion 3 through the feed ball screw mechanism using the feed screw 27 and ball.

Now, Fig. 18 shows a third embodiment of a feed mechanism and, in particular, Fig. 18, similarly to Fig. 2, is a general perspective view of the internal mechanism of the third embodiment.

In Fig. 18, like parts as in Fig. 2 are given the same designations and thus the description thereof is omitted. Here, description will be given below of the structures of only the parts that are different from those shown in Fig. 2.

That is, according to the third embodiment, as shown in Fig. 18, in the feed mechanism 21, a cylindrical-shaped groove cam 28 is fixed to the output shaft of a feed motor 20 with the axis thereof extending in the horizontal direction, and an engaging pin 22b provided on and projected from the outer periphery of the feed shaft 22 is engaged with a cam groove 28a which is formed along the outer periphery of the cylindrical-shaped groove cam 28.

As described above, since the cam groove 28a formed in the cylindrical-shaped groove cam 28 on the output shaft of the feed motor 20 with the axis thereof extending in the horizontal direction is engaged with the engaging pin 22b provided on the feed shaft 22 having a horizontally extending axis, and the cloth hold arm 24 is fixed to the feed shaft 22, similarly to the previously described first embodiment, not only there can be obtained an effect which can be provided due to incorporation of the feed motor 20 within the vertical body portion 3, but also, the feed shaft 22 can be moved linearly in the horizontal direction through the feed cam mechanism comprising the circumferential groove cam 28 and engaging pin 22b while the feed shaft 22 is driven by the pulse motor (feed motor) 20 which is so disposed as to extend in the horizontal direction, so that the cloth hold arm 24 can be moved in approaching and parting directions with respect to the vertical body portion 3.

Now, Fig. 19 shows a fourth embodiment of the feed mechanism and, in particular, Fig. 19, Similarly to Fig. 2, is a general perspective view of the internal mechanism of the fourth embodiment.

In Fig. 19, like parts as in Fig. 2 are given the same designations and thus the description thereof is omitted. Here, description will be given below of the structures of only the parts that are different from those shown in Fig. 2.

That is, according to the fourth embodiment, as shown in Fig. 18, in the feed mechanism 21, instead of the feed motor 20 comprising a pulse motor, there is employed a feed motor 29 comprising a linear stepping motor which includes an output shaft with the axis extending in the horizontal direction and drives the output shaft to advance and retreat, and the feed shaft 22 is connected with the output shaft of the feed motor 29 comprising such linear stepping motor.

As described above, since the advancing and retreating output shaft of the linear stepping motor (feed motor) 20 with the axis thereof extending in the horizontal direction is connected directly with the feed shaft 22 which is formed coaxial with the motor 20 output shaft, and the cloth hold arm 24 is fixed to the feed shaft 22, similarly to the previously described first embodiment, not only there can be obtained an effect which can be provided due to incorporation of the feed motor 20 within the vertical body portion 3, but also, if driven by the horizontally-disposed linear stepping motor (feed motor) 20, the feed shaft 22 in direct connection with the stepping motor 20 can be moved linearly in the horizontal direction so that the cloth hold arm 24 can be moved in approaching and parting directions with respect to the vertical body portion 3.

Now, Fig. 20 shows another embodiment of the needle swing mechanism, that is, a fifth embodiment according to the invention; and, similarly to Fig. 3, Fig. 20 is a schematic perspective view of an internal mechanism of the present needle swing mechanism.

In Fig. 20, like parts as in Fig. 3 are given the same designations and thus the description thereof is omitted. Here, description will be given below of the structures of only the parts that are different from those shown in Fig. 3.

That is, according to the fifth embodiment, as shown in Fig. 20, in a needle swing mechanism 42, there are used a base line motor 40 and a swing width motor 41 respectively having axes which intersect the upper shaft 6 at right angles and extend in the horizontal direction, there are formed worms 40b and 41b respectively on the respective output shafts of the base line motor 40 and swing width motor 41, a sector gear 43d formed in the lower end portion of a base line arm 43 is in meshing engagement with the worm 40b of the base line motor 40, and a sector gear 55d formed in the lower end portion of a swing width arm 55 is in meshing engagement with the worm 41b of the swing width motor 41.

In this manner, in the buttonhole darning sewing machine, since the base line motor 40 and swing width motor 41, which respectively consist of pulse motors, are both stored within the vertical body portion 3 with their axes arranged in parallel to the upper surface of the bed 2, similarly to the previously described first embodiment, not only the space within the vertical body portion 3 can be used effectively but also the number of parts to be mounted on the outside portion of the sewing machine frame 1 can be reduced to thereby make neat the appearance of the sewing machine frame 1.

Now, Fig. 21 shows another embodiment of the needle swing mechanism, that is, a sixth embodiment according to the invention; and, similarly to Fig. 3, Fig. 20 is a schematic perspective view of an internal mechanism of the present needle swing mechanism.

In Fig. 21, like parts as in Fig. 3 are given the same designations and thus the description thereof is omitted. Here, description will be given below of the structures of only the parts that are different from those shown in Fig. 3.

That is, according to the sixth embodiment, as shown in Fig. 21, in the needle swing mechanism 42, there are used a base line motor 40 and a swing width motor 41 respectively having axes which intersect the upper shaft 6 at right angles and extend in the horizontal direction, while cylindrical-shaped groove cams 70 and 71 are respectively connected to the output shafts of the base line motor 40 and swing width motor 41. And, an engaging pin 43e provided in the lower end portion of the base line arm 43 is engaged with a cam groove 70a formed in the outer periphery of the groove cam 70 of the base line motor 40, while an engaging pin 55e provided in the lower end portion of the swing width arm 55 is engaged with a cam groove 71a formed in the outer periphery of the groove cam 71 of the swing width motor 41.

In this manner, in the buttonhole darning sewing machine, since the base line motor 40 and swing width motor 41, which respectively consist of pulse motors, are both stored within the vertical body portion 3 with their axes arranged in parallel to the upper surface of the bed 2, similarly to the previously described first embodiment, not only the space within the vertical body portion 3 can be used effectively but also the number of parts to be mounted on the outside portion of the sewing machine frame 1 can be reduced to thereby make neat the appearance of the sewing machine frame 1.

Now, Fig. 22 shows another embodiment of the cloth cutting knife drive mechanism, which is a seventh embodiment of the invention; and, Fig. 22 is a perspective view of the present cloth cutting knife drive mechanism in which a cloth cutting knife is moved upward and downward by a mechanical drive mechanism and which, in particular, uses a mechanism disclosed in Japanese Patent Publication No. 7-14438 of Heisei.

In Fig. 22, like parts as in Fig. 13 are given the same designations and thus the description thereof is omitted. Here, description will be given below of the structures of only the parts that are different from those shown in Fig. 13.

That is, according to the seventh embodiment, as shown in Fig. 22, a knife mounting plate 31 having a cloth cutting knife 16 is connected through a link 35b to one end portion of a drive lever 35 journaled on a shaft 35a, whereas a drive hook 37 to be engaged with a knife drive arm 36 is rotatably supported on the other end portion of the drive lever 35. The knife drive arm 36 can be moved upward and downward, that is, in directions shown by an arrow A in Fig. 22 in linking with the upper shaft 6. On the other hand, the knife drive hook 37 includes in the upper end portion thereof an engaging recessed portion 37a to be engaged with the knife drive arm 36 and, normally, it is energized and rotated clockwise by a spring 37b.

And, below the above-mentioned knife drive arm 36 and drive hook 37, there are disposed a start rod 38 and a push rod 39. The start rod 38 can be moved in a direction shown by an arrow B in Fig. 22 in linking with a start frame (not shown) provided in the sewing machine. On the other hand, the push rod 39, within the above-mentioned bed 2, can be moved upward and downward due to its engagement with a notch 72a formed on a main cam 72 which can be rotated in linking with the upper shaft 6.

Also, upwardly of the start rod 38, there is disposed a start arm 73. This start arm 73, when started, can be moved in the arrow B direction by the start rod 38 and, when the sewing machine is stopped, can be moved in the reversed direction into engagement with a pin 37c provided in the knife drive hook 37, thereby preventing the knife drive hook 37 against rotation.

Further, upwardly of the push rod 39, there is disposed an operation cam mechanism 74. The operation cam mechanism 74, in linking with the vertical movement of the push rod 39, rotates the drive hook 37 about a shaft 37e which is a connecting point between the drive lever 35 and drive hook 37.

According to the above-mentioned cloth cutting knife drive mechanism, if the sewing machine is driven, then the start rod 38 in linking with the start frame (not shown) is moved in the arrow B direction and thus the start arm 73 is rotated counterclockwise about the shaft 37a, so that the start arm 73 is removed from the engagement with the pin 37c of the knife drive hook 37. In response to this, a projecting portion 37d of the knife drive hook 37 is engaged with the operation cam mechanism 74 and, due to the operation of the operation cam mechanism 74, the knife drive hook 37 is set into its rotation allowable state. In this rotatable state, the buttonhole darning operation progresses and, in the process thereof, the push rod 39 moves in the vertical direction due to its engagement with the notch 72a on the main cam 72 which rotates in linking with the upper shaft 6.

And, due to the operation of the operation cam mechanism 74, the knife drive hook 37 is rotated clockwise about the shaft 37e by the rotational energizing force of the spring 37b, so that the engaging recessed portion 37a of the knife drive hook 37 is engaged with the vertically moving leading end of the knife drive arm 36.

That is, since the drive lever 35 is caused to swing about the shaft 35a, the cloth cutting knife 16 is moved upward and downward at a given timing to thereby cut a given portion of the cloth and form a buttonhole, which ends the buttonhole darning operation.

Now, Fig. 23 shows still another embodiment of the cloth cutting knife drive mechanism, which is an eighth embodiment of the invention; and, Fig. 23 is a perspective view of a drive system for driving a cloth cutting knife.

In Fig. 23, like parts as in Fig. 13 are given the same designations and thus the description thereof is omitted. Here, description will be given below of the structures of only the parts that are different from those shown in Fig. 13.

That is, according to the eighth embodiment, as shown in Fig. 23, a knife mounting plate 31 having a cloth cutting knife 16 is disposed in one end portion of a drive lever 35 journaled on a shaft 35a, whereas a drive hook 37 to be engaged with a knife drive arm 36 is disposed on the other end portion of the drive lever 35. The knife drive arm 36 can be moved upward and downward in linking with the upper shaft 6. On the other hand, the knife drive hook 37 includes in the middle portion thereof an engaging recessed portion 37a to be engaged with the knife drive arm 36 and, normally, it is energized and rotated clockwise by a spring 37b.

And, laterally of the upper end portion of the knife drive hook 37, there is disposed a solenoid 75. The solenoid 75 is structured such that it can bring its plunger 75a into contact with the upper end portion of the knife drive hook 37 to thereby separate the engaging recessed portion 37a from the knife drive arm 36 against the rotational energizing force of the spring 37b.

Therefore, if the plunger 75a of the solenoid 75 is caused to retreat, then the knife drive hook 37 is rotated clockwise about the shaft 37e by the rotational energizing force of the spring 37b, so that the engaging recessed portion 37a can be engaged with the vertically moving leading end of the knife drive arm 36.

By the way, instead of the solenoid 75, an air cylinder unit can also be used.

Now, Fig. 24 is an exploded perspective view of a general example of a cloth cutting knife mounting structure. In general, as shown in Fig. 24, the cloth cutting knife 16 is mounted into a mounting recessed portion 76a, which is formed in a knife mounting piece 76 to be screwed to the lower end portion of the above-mentioned knife mounting plate 31, by a set screw 32 through a washer 32a.

In the ninth embodiment, in order to prevent the possibility that a knife different in size from an exclusive cloth cutting knife can be mounted, there is provided a judge portion which functions as select means.

That is, as shown in Fig. 25, in the mounting recessed portion 76a of the knife mounting piece 76, there is provided a small projection 76b for judgment and, in the exclusive cloth cutting knife 16, in particular, at the position thereof corresponding to the small projection 76b, there is formed a small hole 16a for judgment.

Or, as shown in Fig. 26, in the corner portion of the mounting recessed portion 76a of the knife mounting piece 76, there is formed an inclined portion 76c for judgment and, in the exclusive cloth cutting knife 16, in particular, in the corner portion thereof that corresponds to the inclined portion 76c, there is formed a cut-away portion 16b.

Now, Fig. 27 shows an example of the shape of the cloth cutting knife. In this embodiment, in place of the normal cloth cutting knife 16 (Fig. 27 (a)), as shown in Fig. 27 (b), there is used an exclusive cloth cutting knife 16 having a switch escape hole 16c, or, as shown in Fig. 27 (c), there is used an exclusive cloth cutting knife 16 including a cut-away portion 16d in the corner portion thereof.

And, as shown in Fig. 27 (b), when there is used the exclusive cloth cutting knife 16 having a switch escape hole 16c, as shown in Figs. 28 (a) and (b), a judgment switch 77 is mounted on the back surface of the knife mounting piece 76, while a push switch portion 77a of the judgment switch 77 is exposed to a position which corresponds to the switch escape hole 16c of the mounting recessed portion 76a.

Also, as shown in Fig. 27 (c), when there is used the exclusive cloth cutting knife 16 including the cut-away portion 16d, as shown in Figs. 29 (a) and (b), the push switch portion 77a of the judgment switch 77 mounted on the back surface of the knife mounting piece 76 is exposed to a position which corresponds to the cut-away portion 16d of the exclusive cloth cutting knife 16.

The above-mentioned judgment portion and judgment switch 77 also function as the select means.

Now, Fig. 30 shows an example of the relation between the cloth presser and cloth cutting knife. As shown in Fig. 30, for example, when there is set a cloth presser 15 having a size smaller than that of the cloth cutting knife 16, the cloth cutting knife 16 touches the cloth presser 15.

In view of this, according to the eleventh embodiment, there is provided a judgment portion for judging the size of the cloth presser 15.

As shown in Fig. 31, a forked mounting piece 25 supporting the cloth presser 15 is supported on the leading end portion of the cloth hold arm 24 of the above-mentioned feed mechanism 21 by a stepped screw 78a and a support spring (coil spring) 78b in such a manner that the mounting piece 25 can be swung in directions shown by an arrow C in Fig. 31.

And, on the leading end portion side of the cloth hold arm 24 on which the mounting piece 25 for the cloth presser 15, as shown in Fig. 31, for example, there are embedded a plurality of (in the illustrated embodiment, three) judgment sensors 79a, 79b, 79c each of an optical type in such a manner that they are arranged side by side.

Therefore, as shown in Fig. 31, for example, if a small-sized cloth presser 15 is mounted, then the judgment sensor 79c is covered with a mounting piece 25 for the present cloth presser 15, which can tell that the small-sized cloth presser 15 is mounted.

Also, although not shown, if a medium-sized cloth presser is mounted, then the two judgment sensors 79b and 79c are both covered with a mounting piece for the medium-sized cloth presser, which can tell that the medium-sized cloth presser is mounted. Further, if a large-sized cloth presser is mounted, then the three judgment sensors 79a, 79b and 79c are all covered with a mounting piece for the large-sized cloth presser, which can tell that the large-sized cloth presser is mounted.

By the way, as the judgment portion for judging the size of the cloth presser 15, not only the judgment sensors 79a, 79b and 79c of an optical type but also a judgment switch of a push button type can be used. Also, the number of sensors or switches used depends on the need.

Now, based on the judgment results, a numerical value, which corresponds to the current cloth presser and is to be set in the column No.15 in Fig. 39, is read out from a previously stored table (not shown) and is then set in the column No.15 in Fig. 39.

Next, description will be given below of a control system.

The above-structured buttonhole darning sewing machine is controlled according to a control block structure shown in Fig. 35.

That is, as shown in Fig. 35, to CPU 100, there are connected through buses a ROM 101, a RAM 102, a Y feed counter 103, a base line feed counter 104, a needle swing feed counter 105, a cloth cutting knife counter 106, a thread cutting feed counter 107, an interrupt controller 108, and an I/O interface 109.

By the way, CPU 100 comprises various kinds of control portions and operation means: that is, sewing machine control means; sewing machine drive speed decide means; means for correcting the change amounts of the base line and needle swing width; means for specifying the stitch forming sequence; sewing data read-out means; means for specifying the start of sewing; knife control means; knife vertical movement timing decide means including knife downward movement timing decide means; means for judging the interval of the timings of the upward and downward movements of the knife; side stitch length change means; needle drop control means; means for deciding a reference point for pattern enlargement and reduction; various drive control means; and the like.

In the ROM 101, there are stored programs and defaults for control; for example, there are stored memory portions which are respectively used to store therein a sewing mode, a tension hook matching mode, a thread passing mode, and the like.

In the RAM 102, there are stored various variables for control; for example, there are stored sewing data, base line/needle swing data, and the like.

Each of the Y feed counter 103, base line feed counter 104, needle swing feed counter 105, cloth cutting knife counter 106, and thread cutting feed counter 107 is structured such that, if a count value is written thereinto and a counter start command is written thereinto, then it outputs a count signal of one pulse after passage of the time proportional to the count value, and repeats its counter output at a given cycle until a counter stop command is written thereinto. The interrupt controller 108 is a controller which, if an interrupt signal is input, then allows the CPU 100 to execute an interrupt processing corresponding to the interrupt signal input. The I/O interface 109 is an interface through which the CPU 100 interfaces an external input/output device.

Also, the respective count outputs of the Y feed counter 103, base line feed counter 104, needle swing feed counter 105, cloth cutting knife counter 106, and thread cutting feed counter 107 are connected to the interrupt controller 108 and, in accordance with the count outputs of the respective counters, interrupt processings corresponding to the respective counters are executed.

And, in Fig. 35, an operation panel 110, as shown in Fig. 36, is composed of a display portion and various keys; that is, it is a panel through which an operator carries out various settings and operations necessary for sewing.

A Y feed pulse driver 111 is structured such that, when a Y feed counter output signal from the Y feed counter 103 and a Y feed direction +/- signal from the I/O interface 109 are input thereinto, then it rotates the Y feed pulse motor (that is, the above-mentioned feed motor) 20 by an amount equivalent to 1 pulse each counter output in accordance with +/- of the Y feed direction.

A base line feed pulse motor driver 112 is structured such that, when a base line feed counter output signal from the base line feed counter 104 and a base line feed direction +/signal from the I/O interface 109 are input thereinto, then it rotates the base line feed pulse motor (that is, the above-mentioned base line motor) 40 by an amount equivalent to 1 pulse each counter output in accordance with +/- of the base line feed direction.

A needle swing feed pulse motor driver 113 is structured such that, when a needle swing counter output signal from the needle swing feed counter 105 and a needle swing feed direction +/- signal from the I/O interface 109 are input thereinto, then it rotates the needle swing feed pulse motor (that is, the above-mentioned swing width motor) 41 by an amount equivalent to 1 pulse each counter output in accordance with +/- of the needle swing feed direction.

A thread cutting feed pulse motor driver 114 is structured such that, when a thread cutting feed counter signal from the thread cutting feed counter 107 and a thread cutting feed direction +/- signal from the I/O interface 109 are input thereinto, then it rotates the thread cutting feed pulse motor (that is, the above-mentioned pulse motor) 80 by an amount equivalent to 1 pulse each counter output in accordance with +/- of the thread cutting feed direction.

Also, the thread cutting feed pulse motor driver 114 outputs a signal from the thread cutting feed counter 107 to the interrupt controller 108 as a thread cutting feed counter interrupt.

A sewing machine motor driver 115 is structured such that, responsive to a sewing machine start/stop signal and a sewing machine speed signal from the I/O interface input thereinto, if the sewing machine is to be started, then it rotates the sewing machine motor 5 at a given number of rotations; whereas, if the sewing machine is to be stopped, based on the detection of a needle upper position sensor 116, it allows known constant position stop means to stop the sewing machine motor 5. Here, the needle upper position sensor 116 is used to detect the upper position of the above-mentioned needle bar 8. Also, the upper position detection output of the needle upper position sensor 116 is used as a needle number count input.

And, the sewing machine motor driver 115 outputs the stopping or rotating state of the sewing machine to the I/O interface 109 as a sewing machine status stopping or rotating signal, and also it outputs a signal from the needle upper position sensor 116 to the interrupt controller 108 as a needle upper position interrupt signal.

Further, the sewing machine motor driver 115 outputs signals from a feed reference position sensor 117 and a TG (Tacho-generator) generator 118 to the interrupt controller 108 respectively as a feed reference interrupt and a TG interrupt. The feed reference position sensor 117 is used to control the feed of the Y feed motor, base line feed motor, needle swing feed motor and the like. The TG generator 118 is a generator which generates a one-twenty-fourth square wave each rotation of the sewing machine motor.

By the way, a signal from a sewing machine motor encoder 119 is fed back to the sewing machine motor driver 115.

Now, an active tension driver 120, normally, in accordance with the data that is input thereinto from the RAM 102 through the I/O interface 109, controls the upper thread tension VCM (Voice Coil Motor, that is, the above-mentioned voice coil motor) 60 to thereby apply a tension; and, when the sewing machine status stopping/rotating signal, feed reference signal and TG signal are input thereinto from the sewing machine motor driver 115, that is, at given timings during the rotation of the sewing machine, it controls the upper thread tension VCM 60 to vary the tension thereof.

A presser lift solenoid drive circuit 121 drives a presser lift solenoid 122 in accordance with a presser down /up signal from the I/O interface 109.

A cloth cutting knife down cylinder drive circuit 123 drives a cloth cutting knife down cylinder (that is, the above-mentioned cloth cutting knife air cylinder unit) 30 in accordance with a cloth cutting down/up signal from the I/O interface 109.

A Y feed origin sensor shown in Fig. 35 is used to detect the origin position of the Y feed pulse motor 20, that is, this sensor is the above-mentioned feed origin detect sensor 26.

A base line feed origin sensor shown in Fig. 35 is used to detect the origin position of the base line feed pulse motor 40, that is, this sensor is the above-mentioned base line origin detect sensor 57.

A needle swing feed origin sensor shown in Fig. 35 is used to detect the origin position of the needle swing feed pulse motor 41, that is, this sensor is the above-mentioned swing width origin detect sensor 58.

A presser switch 124 is an operation switch through which an operator, in setting a workpiece, lifts and lowers the above-mentioned cloth presser 15 and thus the presser switch 124 is used in connection with an operation to depress the pedal of the sewing machine.

A start switch 125 is an operation switch through which an operator, in setting a workpiece, starts a sewing operation and thus this is also used in connection with the above-mentioned sewing machine pedal depressing operation.

A thread cutting feed origin sensor 126 is used to detect the moving origin position of the above-mentioned upper thread scissors. That is, in the upper thread scissors and the drive mechanism for driving the same which have been respectively discussed in connection with Fig. 32, for example, there is provided a thread cutting feed origin sensor 126 of a close approach type used to detect the origin position of the arm 81 which swings with the output shaft 80a of the pulse motor 80 as the fulcrum thereof; and, in the arm 81, there is provided a thread cutting feed origin detect magnet 126a which consists of the present thread cutting feed origin sensor 126.

Also, a needle swing right and left detect switch in Fig. 35 is the above-mentioned needle swing right and left position detect sensor 59.

A cloth cutting knife drive request switch 127 is used to lower and drive the above-mentioned cloth cutting knife 16.

A knife size recognize means in Fig. 35 is used to confirm whether the cloth cutting knife 16 of a proper size is mounted or not and, in particular, the present knife size recognize means is the above-mentioned judgment switch 77.

A presser size recognize means in Fig. 35 is used to confirm whether the above-mentioned cloth presser 15 of a proper size is mounted or not and, in particular, the present presser size recognize means is the above-mentioned judgment sensor 79 (79a, 79b, 79c).

A knife up/down detect switch in Fig. 35 consists of the above-mentioned cloth cutting knife up/down position sensors 34a and 34b.

And, the operation panel 110, as shown in Fig. 36, includes various keys and display portions.

That is, the operation panel 110 includes: a sewing key 131, and an LED display portion 132 which, when the sewing key 131 is depressed, is turned on to display that the sewing machine is set in a sewing mode; and, a select key 132, and LED display portions 134, 135, 136, 137, and 138 which, each time the select key 132 is depressed, are turned on sequentially to display the pattern No., parameter No., speed setting mode, thread insertion mode, tension hook matching mode.

The operation panel 110 further includes: a numeric value display portion 140 which is composed of a pattern display portion 141 comprising a two-digit LED segment, and a parameter display portion 142 comprising a four-digit LED segment; a minus key 143 and a plus key 144 respectively for decreasing or increasing the numeric value of the numeric value display portion 140 by ± ; a down key 145 and an up key 146 respectively for decreasing or increasing the numeric value of the numeric value display portion 140 each given unit; and, a set key 147 which is used as a thread insertion key or a tension hook matching key. Further, although not shown, in the operation panel 110, there is provided a switch which is used to select the above-mentioned right-handed or left-handed sewing of the buttonhole darning operation.

By the way, the operation panel 110, which includes the above-mentioned various keys, further has functions respectively serving as buttonhole/knife blade length setting means, buttonhole formation width direction position setting means, means for setting the interval between the lock stitch sewing portion and buttonhole end portion, pattern enlargement/reduction setting means, constant stitch number/pitch setting means, and the like.

Next, description will be given below of a concrete embodiment of control with reference to Fig. 37 showing a general flow of control to be executed in accordance with the control blocks shown in Fig. 35.

The control to be discussed below can be executed through transmission and reception of signals between a CPU 100, a ROM 101, and a RAM 102: in particular, the CPU 100 includes various control portions (sewing machine control means, sewing machine speed decide means, base line and needle swing width change amount correct means, stitch formation sequence specify means, sewing data read-out means, start specify means for setting a sewing start position, knife control means, vertical movement timing decide means including knife lowering timing decide means, judging means for judging the interval between the upward and downward movement timings of the knife, side sewing length change means, needle drop control means, pattern enlargement/reduction reference point decide means, various drive control means, and the like) and operation means; the ROM 101 stores therein programs and defaults for control including, for example, memory portions respectively for storing sewing mode and tension hook matching mode, and a thread insertion mode, and the like; and, the RAM 102 stores therein various variables for control including, for example, sewing data, base line/needle swing data and the like. Also, the CPU 100 executes given controlling operations in accordance with signals input from the operation panel 110 which has the functions respectively serving as the buttonhole/knife blade length setting means, buttonhole formation width direction position setting means, means for setting the interval between the lock stitch sewing portion and buttonhole end portion, pattern enlargement/reduction setting means, constant stitch number/pitch setting means, and the like.

As shown in the general flow of Fig. 37, if the power supply is turned on, then, at first, in Step S1, an operation panel setting processing is called and various setting processings are carried out by the operation panel 110. The various setting operation by the operation panel 110 is executed on until the sewing key 131 is switched on in the next step S2 and, after the sewing key 131 is tumed on, in the next step S3, a sewing data create processing is called and sewing data are created. By the way, in the above-mentioned step S2, if the sewing key 131 is not on, then the processing goes back to the above-mentioned step S1.

After the sewing data are created, in the next step S4, there is executed an output for lowering the cloth presser 15 and, next, in Step S5, a machine origin retrieval processing is called, thereby retrieving the machine origins of the Y feed pulse motor 20, base line feed pulse motor 40, and needle swing feed pulse motor 41. After then, in Step S6, a sewing start movement processing is called, in which the Y feed pulse motor 20, base line feed pulse motor 40, and needle swing feed pulse motor 41 are driven and moved to the sewing start positions. Next, in Step S7, there is executed an output for lifting the cloth presser 15 and, after then, the processing advances to the next step S8.

In Step S8, the state of the sewing key 131 is checked: that is, if the sewing key 131 is on, then the processing goes back the above-mentioned step S1, in which the operation panel setting processing is performed again; or, if the sewing key 131 is not on, then the processing goes to the next step S9. In Step S9, the presser switch 124 is checked for the state thereof: that is, if the presser switch 124 is on, then the processing advances to the next step S10; or, if the presser switch 124 is not on, then the processing goes back to the above-mentioned step S8.

In Step S10, it is checked whether the cloth presser 15 is lifting or not: that is, if it is found lifting, then there is executed an output for lowering the cloth presser 15 in the next step S11; or, if it is found not lifting, then there is executed an output for lifting the cloth presser 15 in the next step S12 and, after then, the processing returns to the above-mentioned step S8.

After execution of the cloth presser lowering output, in the next step S13, the presser switch 124 is checked for the state thereof: that is, if the presser switch 124 is on, then in the above-mentioned step S12, there is executed an output for lifting the cloth presser 15 and, after then, the processing goes back to the above-mentioned step S8; or, if the presser switch 124 is not on, then the processing advances to the next step S14. In Step S14, the start switch 125 is checked: that is, if the start switch 125 is found "on", then the processing advances to the next step S15; or if the start switch 125 is found "not on", then the processing goes back to the above-mentioned step S13.

And, in Step S15, a sewing processing is called and a sewing operation is thereby started. After the sewing operation is finished, in the next step S16, there is executed an output for lifting the cloth presser 15 and, after then, the processing returns to the above-mentioned step S8.

Next, description will be given below in detail of the above-mentioned operation panel setting processing (Step S1), sewing data creation processing (Step S3), mechanical origin retrieval processing (Step S5), and sewing processing (Step S15) respectively to be carried out according to the general flow shown in Fig. 37.

In particular, Fig. 38 shows a subroutine for the operation panel setting processing (Step S1), in which, firstly, in Step S101, the select key 133 is checked: that is, if it is on, then the select number is incremented by 1 in the next step S102 and, after then, the processing advances to the next step S103; or, if it is not on, then the processing advances to Step S105.

In Step S103, the select number is checked: that is, if the select number exceeds the maximum number [4], then [0] is set in the select number to return the select number to 0 in the next step S104 and, after then, the processing advances to the next step S105; or, if the select number is the maximum number [4] or less, then the processing advances to Step S105.

In Step S105, it is checked whether the select number is 0 or not: that is, if it is 0, then the processing advances to Step S106, in which a pattern change processing is executed, and, after then, the processing advances to the above-mentioned step S2 of the general flow (Fig. 37); or, if it is not 0, then the processing advances to step S107.

In Step S107, it is checked whether the select number is 1 or not: that is, if it is 1, then the processing advances to Step S108, in which a parameter change processing is executed, and, after then, the processing advances to the above-mentioned step S2 of the general flow (Fig. 37); or, if it is not 1, then the processing advances to step S109.

In Step S109, it is checked whether the select number is 2 or not: that is, if it is 2, then the processing advances to Step S110, in which a speed change processing is executed, and, after then, the processing advances to the above-mentioned step S2 of the general flow (Fig. 37); or, if it is not 2, then the processing advances to step S111.

In Step S111, it is checked whether the select number is 3 or not: that is, if it is 3, then the processing advances to Step S112, in which a thread insertion mode is set, and, after then, the processing advances to the above-mentioned step S2 of the general flow (Fig. 37); or, if it is not 3, then the processing advances to step S113.

In Step S113, it is checked whether the select number is 4 or not: that is, if it is 4, then the processing advances to Step S114, in which a tension hook matching mode is set, and, after then, the processing advances to the above-mentioned step S2 of the general flow (Fig. 37); or, if it is not 4, then the processing directly advances to the above-mentioned step S2.

Next, description will be given below se