BACKGROUND OF THE INVENTION
The present invention relates to a stencil disposal unit and stencil
disposal method, and more particularly to a stencil disposal unit and stencil disposal
method in which a used stencil wound around the outer periphery of a printing drum
of a rotary stencil printing machine is transported to a stencil disposal container
or the like and then disposed.
Upon an investigation by the inventors of the present invention,
a stencil disposal unit provided in a rotary stencil printing machine is envisioned,
such as shown in Fig. 8, in which the stencil disposal unit 138 automatically disposes
of a used stencil from a printing drum.
The stencil disposal unit 138 is disposed in proximity to the periphery
of a printing drum 112, and minimally has a pair of stencil disposal rollers 139,
which are in mutual contact and which rotate in mutually opposite directions. The
stencil sheet M is fed in between the stencil disposal rollers 139 and transported
and recovered in a stencil disposal container 140 to the rear thereof.
In this rotary stencil printing machine the prepared stencil sheet
M is automatically fed to and wound around the printing drum 112.
Specifically, as shown in Fig. 8, after a stencil sheet M is pulled
out from a stencil sheet roll and a stencil is made from the stencil sheet M using
a thermal printing head 107, it is transported to the printing drum 112. After
transport to the printing drum 112, the end part of the stencil sheet M is grabbed
by the clamping plate 119 at the printing drum 112, and wound around the outer
periphery of the printing drum 112 by rotation of the printing drum 112. When the
fixing of the stencil sheet M to the printing drum 112 is completed, a cutter
unit 111 cuts the stencil sheet M.
The stencil sheet M is formed by a thermoplastic resin film, such
as a polyethylene terephthalate film, a vinylidene chloride film, a polyester film,
or a polypropylene film or the like, to which an ink permeable porous sheet (porous
tissue carrier), made of a natural fiber, a chemical fiber, a synthetic fiber,
or a thin paper, non-woven cloth, silk gauze or the like that is a mixture thereof
is adhered, thereby forming a thermally sensitive stencil sheet. For a rolled stencil
sheet M such as shown in Fig. 8, the ink permeable porous sheet is disposed on
the outside surface. When printing is done, the ink permeable porous sheet makes
contact with the outer surface of the printing drum 112.
When printing, the printing drum 112 is caused to rotate in the counterclockwise
direction as shown in Fig. 8, the print paper (not shown in the drawing) being
fed between the printing drum 112 and a pressure means (not shown in the drawing),
which presses the print paper up against the image part of the stencil sheet M
attached to the printing drum 112. By doing this, ink fed by an ink feeding means
(not shown in the drawing)within the printing drum 112 passes through an ink-permeable
part on the outer wall of the printing drum 112, and is transferred to the print
paper via the perforation parts of the stencil sheet M so as to form an image thereon.
When the printing is completed, the disposal operation is performed
by the stencil disposal unit 138. When disposing the stencil sheet M, as shown
in Fig. 9, a mechanism not shown in the drawing releases the grip of the clamping
plate 119 on the stencil sheet M, thereby freeing up the end part of the stencil
sheet M that had been held. The printing drum 112 is then caused to rotate in the
counterclockwise direction shown in Fig. 8, so that the freed-up end part of the
stencil sheet M is fed between the pair of stencil disposal rollers 139, causing
disposal of the stencil sheet M.
SUMMARY OF THE INVENTION
According to an investigation by the inventors, however, with the
stencil disposal unit 138, the freed-up end part of the stencil sheet M that had
been held by the clamping plate 119 has a tendency to curl, as shown in Fig. 9.
If the stencil sheet M curls, this curl can cause the end to miss
the space between the pair of stencil disposal rollers 139, so that it is not transported
into the stencil disposal container 140. Additionally, because of the curving
tendency of the rolled stencil sheet M, the expansion of the ink permeable porous
sheet making up the stencil sheet M due to humidity in the air, and the influence
of temperature and static electricity, the curl of the end part of the stencil
sheet M often tends to be in a direction away from the printing drum 112. By the
rotation of the printing drum 112 during stencil disposal, there is resistance
that urges the curl to move further away from the printing drum 112, thereby aggravating
the problem of curl.
For this reason, it can be envisioned that, in the stencil disposal
unit 138, as shown in Fig. 11, an endless guide belt 145 is wound between a stencil
disposal roller 139a, which, of the pair of stencil disposal rollers 139, is farther
from the printing drum 112, and a pulley 146 which is disposed above the clamping
plate 119, so as to guide a curled end of the stencil sheet M to between the pair
of stencil disposal rollers 139. If this is done, the guide belt 145 is rotationally
driven by the rotation of the stencil disposal rollers 139.
Another arrangement that can be envisioned is, as shown in Fig. 11,
to provide an air blower 160 that applies pressure to the printing drum 112 side
of the end part of the stencil sheet M to be curled, the air flow from the air
blower 160 guiding the end part of the stencil sheet M to between the pair of
stencil disposal rollers 139.
It is also possible to combine elements of the guide belt 145 and
the air blower 160.
However, as the investigation by the inventors progressed further
it was understood that, in the configuration in which a guide belt 145 is provided
in the stencil disposal unit 138, the position at which the guide belt 145 is provided
is very close to the clamping plate 119, so that it interferes with the swinging
range of the clamping plate 119.
For this reason, when the clamping plate 119 is caused to swing,
it is necessary to have an added moving mechanism such that the pulley 146 onto
which the guide belt 145 is wound is moved about the stencil disposal rollers 139
as a center, so that the guide belt 145 does not come into contact with the clamping
plate 119.
While it can be envisioned that the stencil disposal unit 138 having
the guide belt 145 be positioned at a distance from the clamping plate 119, thereby
eliminating the need for the added moving mechanism, when the stencil disposal
unit 138 is moved away from the clamping plate 119, because the angle through
which the printing drum 112 is turned after the clamping plate 119 is released
becomes larger, the rotation of the printing drum 112 as noted above results in
a large resistance that urges the curl to move away from the printing drum 112,
so that it is not possible to establish the position of the end part thereof,
leading to the problem of missed disposal operation.
If an air blower 160 is used, although this does not involve the
swinging range of the clamping plate 119, another moving mechanism for the motor
required by the air blower 160 is still required. Additionally, making the air
blower 160 itself small will reduce the air output, making it necessary to bring
this device close to the clamping plate 119.
Thus, in the investigation conducted by the inventors as to the stencil
disposal unit 138, it was understood that the adopting of a configuration for the
purpose of preventing faulty disposal of a used stencil was limited in terms of
the positional relationship with respect to the clamping plate 119, making it
difficult to achieve a suitable configuration.
The printing drum 112 is configurated to enable removal in the axial
direction for the purpose of maintenance inspections or the like. In this type
of configuration, if the clamping plate 119 and the stencil disposal unit 138 are
in mutual proximity, when the printing drum 112 is pulled out, there is a risk
that contact by the printing drum 112 will cause the clamping plate 119 to come
into contact with the guide belt 145, the air blower 160 or the like of the stencil
disposal unit 138.
Accordingly, the present invention was made by the above mentioned
studies and has an object to provide a stencil disposal unit arid stencil disposal
method that substantially omit a restriction on an arrangement of structural elements
due to a configuration of a printing drum, occurrence of curl of a stencil sheet
or the like, and also perform disposal operation of the stencil sheet in stable
and with a simple structure not requiring an additional mechanism such as a movable
mechanism.
In accordance with the present invention, a stencil disposal unit
disposing a stencil sheet an end part of which is clamped at and wound onto a printing
drum of a rotary stencil printing machine having a rotational drive mechanism capable
of causing the printing drum to rotate in a winding direction with respect to
an end part of a stencil sheet released from a clamp and in a reverse direction
opposite to the winding direction, comprises: a pair of stencil disposal rollers
arranged in an area around a periphery of the printing drum and rotatable respectively
in opposite directions in mutual contact with each other, thereby pulling in the
end part of the stencil sheet so as to transport the stencil sheet to a predetermined
disposal position. Here, by rotating the printing drum through a predetermined
angle in the winding direction, the end part of the stencil sheet is guided to
a pull-in position at which the stencil sheet is to be pulled in, and the printing
drum is rotated in the reverse direction, as the stencil sheet is pulled in at
the pull-in position by the pair of disposal rollers.
Beside, in another aspect of the present invention, a stencil disposal
method disposing a stencil sheet an end part of which is clamped at and wound around
a printing drum of a rotary stencil printing machine, comprises: releasing the
end part of the stencil sheet from a clamp; causing the printing drum to rotate
in a winding direction with respect to the end part of the stencil sheet released
from the clamp, so as to guide the end part of the stencil sheet to a pull-in position;
and causing the printing drum to rotate in a reverse direction opposite to the
winding direction, as pulling in the end part of the stencil sheet.
BRIEF DESCRIPTIONS OF THE DRAWINGS
- Fig. 1 is side view showing the schematic configuration of a rotary stencil
printing machine to which a stencil disposal unit according to an embodiment of
the present invention is applied;
- Fig. 2 is a side view showing the configuration in the area around the stencil
disposal unit according to the embodiment;
- Fig. 3 is a front view showing a part of the configuration of the stencil disposal
unit according to the embodiment;
- Fig. 4 through Fig. 7 are side views showing the sequence operation of stencil
sheet disposal in the stencil disposal unit according to the embodiment;
- Fig. 8 is a side view showing a part of the configuration of a rotary stencil
printing machine to which a stencil disposal unit studied by the inventors of the
present invention is applied;
- Fig. 9 and Fig. 10 are side views showing the stencil sheet disposal operation
of the stencil disposal unit studied by the inventors; and
- Fig. 11 is a side view showing a stencil disposal unit which is the object
of further study by the inventors.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
An embodiment of a stencil disposal unit and stencil disposal method
according to the present invention is described in detail below, with references
being made to relevant accompanying drawings.
As shown in Fig. 1, a rotary stencil printing machine A has an original
reading section 1, a stencil making section 2, and a printing section 3, these
being controlled by a controller 28.
The original reading section 1 is an image scanner, having a line
image sensor 4 and an original feed roller 5 aligned in the main scan direction
(vertical paper direction in Fig. 1) so as to perform reading of an image of an
original D, which is transported in the sub-scanning direction.
The original is transported by the original feed roller 5 in the
sub-scanning direction (the left direction indicated by the arrow X in the drawing),
and the image of the original is read by the line image sensor 4. The original
reading section 1 is not restricted to this configuration, and can alternately
have a configuration in which the line image sensor is moved in the sub-scanning
direction relative to a fixed original so as to read the image of the original.
Thus, the image of the original reading section 1 is read by the
relative motion between the line image sensor 4 and the original.
The stencil making section 2 has a stencil sheet roll support 6,
which support the rolled stencil sheet M, a thermal printing head 7, which is made
of a plurality of heat sources aligned in a single row, original feed rollers 8
and 9, a stencil sheet guide roller 10, and a cutter unit 11.
The stencil sheet M is formed by a thermoplastic resin film, such
as a polyethylene terephthalate film, a vinylidene chloride film, a polyester film,
or a polypropylene film or the like, to which an ink permeable porous sheet (porous
tissue carrier), made of a natural fiber, a chemical fiber, a synthetic fiber,
or a thin paper, non-woven cloth, silk gauze or the like that is a mixture thereof
is adhered, thereby forming a thermally sensitive stencil sheet. As shown in Fig.
1, the stencil sheet M is rolled, with the ink permeable porous sheet disposed
on the outer surface of the roll.
At the stencil making section 2, a continuously rolled stencil sheet
M is selectively heated individually by the plurality of heat sources of the thermal
printing head 7, thereby performing a dot matrix type thermal perforation on the
thermoplastic resin film of the stencil sheet M. After this is done, the cutter
unit cuts one stencil sheet M away from the rolled stencil sheet, the thus-prepared
stencil sheet M being then conveyed to the printing section 3.
The printing section 3 has a printing drum 12 which has a cylindrically
formed porous ink-permeable peripheral wall made of an ink-permeable material such
as a porous metal sheet or mesh, an ink-supplying device 15 formed by a squeegee
roller 13 and a doctor roller 14 disposed inside the printing drum 12, and a pressure
roller 16 that can approach and move away from the printing drum 12. The printing
drum 12 is rotationally driving about its center by a rotational drive mechanism,
under the control of the controller 28.
The printing drum 12 is provided with a clamping device 17, which
clamps the end part of the stencil sheet M. The clamping device 17 is controlled
by the controller 28 and, as shown in Fig. 2, has a stencil clamping base 18 that
protrudes from a part of the outer peripheral surface of the printing drum 12.
The stencil clamping base 18 is provided with a clamping plate 19 that is supported
so as to be rotatable about a pivot point substantially in parallel with the rotational
axis of the printing drum 12. A magnet 20 that pulls in the clamping plate 19
is provided on the upper surface of the stencil clamping base 18.
The end part of a stencil sheet M that is conveyed from the stencil
making section 2 to the printing section 3 is grabbed by the clamping plate 19,
which is pulled by the magnet 20. The printing drum 12 rotates in the counterclockwise
direction shown in Fig. 1 an Fig. 2, that is, in the direction along the direction
in which the stencil sheet M end is fed in, and the stencil sheet M is wound around
and attached to the peripheral wall surface of the printing drum 12. When this
is done, the ink permeable porous sheet side of the stencil sheet M comes into
contact with the printing drum 12.
As shown in Fig. 2, the rotational drive mechanism that rotationally
drives the printing drum 12 is formed by a drive motor 22 and a gear train that
transmits rotation of the drive motor 22 to the printing drum 12. The gear train
has a driving gear 23 fixed to a rotating shaft 22a of the driver motor 22, a
driven gear 24 provided on the printing drum 12, and an intermediate gear 25 that
meshes with both the driving gear 23 and the driven gear 24. The printing drum
12, therefore, by the forward and reverse rotation of the drive motor 22, is caused
to rotate in the forward and reverse directions via the above-noted gear train.
The rotational condition of the drive motor 22 is detected by a rotation
detection section, which as shown in Fig. 2, is formed by a slit plate 26 fixed
to the rotational shaft 22a of the drive motor 22 and which rotates in concert
therewith, and a detector 27 disposed on the motor 22,'for example, in opposition
with the slit plate 26.
The slit plate 26 has a plurality of open slits 26a arranged in a
radial pattern in the rotation direction about the center of the rotational shaft
22a. The detector 27 is formed by a light source/sensor pair, which outputs a pulse
signal responsive to the passage and blockage of light at the slit parts 26a.
This signal is used to detect the rotational condition of the drive motor 22. The
detection signal of the detector 27 is output to the controller 28, which controls
the drive motor 22, processing being performed based on a count of the pulses
of this signal.
Specifically, the pulse signal of the rotational drive mechanism
is continuously input at an interval corresponding to the detection period (frequency)
of the slits 26a, and counted by the controller 28. At the controller 28, a detection
signal from a reference position detector (not shown in the drawing) is also input.
The reference position detector detects each time the printing drum 12 reaches
a reference position, at which point it outputs a reset signal. At the controller
28, the input of this reset signal resets the count value, at which point the
rotational angle of the printing drum 12 is output. Thus, the controller 28 calculates
the rotational angle of the printing drum 12 from the reference position.
The reference position of the printing drum 12 in this embodiment
is a position where the clamping device 17 is precisely above, as shown in Fig.
2, this being the position at which the end part of a stencil sheet M transported
from the stencil making section 2 is grabbed by the clamping device 17, and the
position at which the clamping device 17 releases the end part of a stencil sheet
M after completion of printing.
As shown in Fig. 1, a paper feed section 30 is provided at one end
of the printing section 3 (left side in Fig. 1), and a paper discharging section
31 is provided at the other end of the printing section 3 (right side in Fig. 1).
The paper feed section 30 has a paper feeding tray 32 into which
print paper P is stacked, a pick-up roller 33 that feeds print paper P from the
paper feeding tray 32 one sheet at a time, and a paper feed timing roller 34 disposed
between the printing drum 12 that prints onto the print paper P and the pressure
roller 16.
The paper discharging section 31 has a grabbing claw 35 that peels
the print paper P from the printing drum 12, a paper disposal feed belt 36, and
a paper receiving tray 37 into which printed print papers P are stacked.
When printing is done, printing ink of a predetermined color is supplied
to the inner peripheral surface of the printing drum 12 by the ink supplying device
15. The printing drum 12 rotates in the counterclockwise direction in Fig. 1 and
Fig. 2, about its own center axis, by means of the rotational drive mechanism.
The print paper P moves from left to right in Fig. 1, by the paper feed timing
roller 34, in accordance with a predetermined timing in synchronization with the
rotation of the printing drum 12, and is fed between the printing drum 12 and
the pressure roller 16. The pressure roller 16 presses the print paper P&peseta;up
against the stencil sheet M that is wound around the outer peripheral surface of
the printing drum 12, so that stencil printing is done onto the print paper P
with ink of the predetermined color.
In this rotary stencil printing machine, a stencil disposal unit
38 which peels a used stencil sheet M from the printing drum 12 and disposes of
it after printing is completed is provided on one side of the printing section
3 (right side in Fig. 1). This stencil disposal unit 38 is controlled by the controller
28 as described below, and is chiefly formed by stencil disposal rollers 39 and
a stencil disposal container 40. The controller of the stencil disposal unit 38,
of course, can be provided separately from the controller of the rotational drive
mechanism 28 and the clamping device 17.
The stencil disposal rollers 39 are disposed in an area around the
printing drum 12, at a location which avoids a location above the clamping device
17 when the printing drum 12 is at the above-noted reference position. The stencil
disposal rollers 39 form a pair of rollers in mutual contact as they rotate in
mutually opposite directions, and constitute the upper and lower stencil disposal
rollers 41 and 42.
In this embodiment, a plurality of pairs of upper and lower stencil
disposal rollers 41 and 42 are provided, separated from one another on supporting
shafts 43 and 44 that are substantially parallel to the center axis of the printing
drum 12. Of the plurality of upper and lower stencil disposal rollers 41 and 42,
some upper and lower stencil disposal rollers 41a and 42a are formed so as to have
a larger width than other upper and lower stencil disposal rollers 41b and 42b,
an endless guide belt 45 being wound around the wider lower stencil disposal rollers
42a. The lower stencil disposal rollers 42a have grooves of a depth corresponding
to the thickness of the guide belt 45 formed in the center thereof in the width
direction. The guide belt 45 engages in this groove, and at a position of contact
of the upper stencil disposal roller 41a and the lower stencil disposal roller
42a, the surface of both the lower stencil disposal roller 42a and the guide belt
45 are continuous and smooth.
The guide belt 45 is wound on a pulley 46 that serves as a rotational
element positioned at a distance from the lower stencil disposal roller 42a. The
pulley 46, in the same manner as the corresponding lower stencil disposal roller
42a, has a groove of a depth corresponding to the thickness of the guide belt
45 and receives the guide belt 45 therein. The pulley 46 is fixed to a shaft 47
that is parallel to the supporting shafts 43 and 44.
The supporting shafts 43 and 44 and the shaft 47 are rotatably mounted
by the two ends thereof to two side plates 49 within the rotary stencil printing
machine, via bearings 48 located at both ends. Mutually meshing gears 50 and 51
are provided on one end of the supporting shafts 43 and 44. One of the gears 50
and 51 is rotationally driven by a drive mechanism (not shown in the drawing).
This rotational drive mechanism is controlled by the controller 28. By the rotational
drive from the rotational drive mechanism, the supporting shafts 43 and 44, as
shown by the arrow in Fig. 2, come into contact with the upper and lower stencil
disposal rollers 41 and 42 and rotate them in mutually opposing directions. The
guide belts 45, by the rotation of the lower stencil disposal rollers 42a, are
driven in the direction of the arrow in Fig. 2.
The stencil disposal container 40 is formed as a box disposed to
the rear of the rotational direction of the stencil disposal rollers 39 (upper
and lower stencil disposal rollers 41 and 42).
The stencil disposal unit 38 also has a guide plate 52, disposed
in the area around the periphery of the printing drum 12, this being provided between
the above-described reference position of the printing drum 12 and the position
of the stencil disposal rollers 39 in the opposite direction when the stencil
sheet M is being attached and printing is being done.
The stencil disposal unit 38 also has a stencil disposal sensor 53,
which has a light emitter and a light receiver, light between the light emitter
and light receiver being emitted to and received from the part of the printing
drum 12 in contact with the upper and lower stencil disposal rollers 41 and 42.
The stencil disposal unit 38 further has a peeling claw 54 provided
so that it can swing about the pivot shaft 55 that is fixed in proximity to the
upper stencil disposal roller 41. The swing action of the peeling claw 54 is driven
by a solenoid 56. The end 54a of the peeling claw 54 driven by the solenoid 56
moves between a peeling position by protruding outwardly toward the printing drum
12 and a retracted position by retracting toward the upper stencil disposal roller
41.
Next, the stencil disposal operation in the stencil disposal unit
38 configured as described above is described in detail below.
First, after the above-noted print is completed, as shown in Fig.
4, with the printing drum 12 at the reference position, the clamping plate 19 is
caused to swing, so as to release the end part of the used stencil sheet M that
the clamping plate 19 is clamping. At this point, assume that the end of the released
stencil sheet M, similar to the case studied in the past, has a curl in the direction
away from the printing drum 12.
Next, as shown in Fig. 5, the printing drum 12 is caused to rotate
in a direction that is the opposite from the direction during attachment of the
stencil sheet M and printing therewith, this being the clockwise direction in Fig.
5. By doing this, the stencil sheet M attached to the printing drum 12 is rotated
and moved from its freed-up end in the direction of the printing drum 12. When
this is done, the stencil sheet M receives resistance by the rotation of the printing
drum 12 in the reserve direction so that the stencil sheet M moves closer to the
printing drum 12. The curl at the end of the stencil sheet M, by the action of
the reverse rotation of the printing drum 12, is prevented by the guide plate 52
from deflecting, up until the stencil disposal rollers 39.
Next, as shown in Fig. 6, accompanying the reverse rotation of the
printing drum 12, at the point at which the end part of the stencil sheet M moves
up to the stencil disposal rollers 39, the clockwise rotation of the printing drum
12 is stopped. When this is done, the end part of the stencil sheet M, by the
curl that has developed therein, attempts to enter between the upper and lower
stencil disposal rollers 41 and 42. The fact that the end part of the stencil sheet
M has moved as far as the stencil disposal rollers 39 is detected by the relationship
between the rotational angle of the printing drum 12 from a reference position
calculated based on a count signal output to the controller 28 from the rotational
detector formed by the slit plate 26 and the detector 27 and the pre-established
position of the stencil disposal rollers 39. The fact that the end part of the
stencil sheet M has reached the stencil disposal rollers 39 can also be detected
from the blocking of light between the light emitter and light receiver of the
stencil disposal sensor 53 by the end part of the stencil sheet M.
Next, as shown in Fig. 7, the printing drum 12 is caused to rotate
in the same direction as when the stencil sheet M is attached and when printing
is done, this being the counterclockwise direction in Fig. 7. When this is done,
the upper and lower stencil disposal rollers 41 and 42 are rotationally driven
as described above (direction of the arrow in Fig. 7). With the rotation of the
lower stencil disposal roller 42a, the guide belt 45 is driven in the direction
of the arrow of Fig. 7.
With counterclockwise rotation of the printing drum 12 and drive
of the stencil disposal rollers 39 or the like, the used stencil sheet M is transported
to within the stencil disposal container 40 and retrieved therein, this completing
the disposal of the stencil sheet M. Whether the stencil sheet M has been transported
and placed in stencil disposal container 40 is detected by the restoration of light
emission and reception at the light emitter and light receiver of the stencil
disposal sensor 53.
During the disposal operation of the stencil sheet M, after the end
part of the stencil sheet M moves to the stencil disposal rollers 39, and up until
the time when the stencil sheet M is transported to within the stencil disposal
container 40 and retrieved therein, the end part 54a of the peeling claw 54 moves
to the peeling position close to the printing drum 12. When this occurs, the end
54a of the peeling claw 54 peels away the stencil sheet M from the peripheral wall
of the printing drum 12, and operates so as to guide the stencil sheet M between
the upper and lower stencil disposal rollers 41 and 42 of the stencil disposal
rollers 39. When the clamping device 17 passes the stencil disposal rollers 39
when disposing the stencil sheet M and in general with regard to the cases of
attaching the stencil sheet M and performing printing, as shown in Fig. 4 to Fig.
6, the end part 54a moves to the retracted position by retracting towards the upper
stencil disposal roller 41, so as to avoid contact with the clamping device 17.
Additionally, during the above-noted stencil disposal operation,
the guide belt 45 acts so as to guide the stencil sheet M between the upper and
lower stencil disposal rollers 41 and 42 of the stencil disposal rollers 39. Specifically,
the printing drum 12 is caused to rotate in the clockwise direction, so that the
end part of the stencil sheet M moves up to the stencil disposal rollers 39, at
which point if the end part of the stencil sheet M misses the space between the
upper and lower stencil disposal rollers 41 and 42, the end stencil sheet M is
appropriately guided therebetween.
As described above, in a stencil disposal unit 38 according to an
embodiment of the present invention, in order to dispose of a used stencil sheet
M clamped at and wound around a printing drum 12, the clamp of the end part of
the stencil sheet M is released, the printing drum 12 is caused to rotate in the
clockwise direction, which is the direction in which the stencil sheet M with the
freed-up end is wound onto the printing drum 12, the freed-up end of the stencil
sheet M is guided to a position at which it is to be pulled in by the stencil
disposal rollers 39, and the printing drum 12 is then rotated in the direction
that is the opposite of the direction of winding the stencil sheet M.
That is, in the stencil disposal unit 38, because the end part of
the stencil sheet M is released from the clamped condition, the printing drum 12
is caused to rotate in the direction of winding the stencil sheet M, and the end
of the stencil sheet M is fed up to the stencil disposal rollers 39, from which
point the printing drum 12 is caused to rotate in the direction opposite the winding
direction, the resistance is received such that causes the curl that develops in
the end part of the stencil sheet M to move toward the printing drum 12 as it
is fed to the stencil disposal rollers 39, thereby preventing faulty disposal operation
due to the curl.
Also, because the released end of the stencil sheet M moves toward
the stencil disposal rollers 39 in a condition in which resistance is received
so that the curl at the end part of the stencil sheet M moves toward the printing
drum 12, unlike in past, in which the configuration of the printing drum such
as the clamping device is restricted on the layout, it is possible to have a layout
of the stencil disposal unit 38 with a high degree of freedom.
Additionally, it is not necessary to provide a additional moving
mechanism (such as a guide belt moving mechanism or air blower as used in the past)
in order to guide the curl that develops in the stencil sheet M to the stencil
disposal rollers 39, thereby enabling a simple configuration.
By adopting the guide plate 52, when the printing drum 12 is rotated
in the direction of winding of the stencil sheet M, it is possible to hold the
curled end of the stencil sheet M so that it does not deflect until it reaches
the stencil disposal rollers 39, thereby enabling more reliable operation.
By adopting the guide belt 45, it is possible to appropriately guide
the stencil sheet M to between the stencil disposal rollers 39, thereby enabling
more reliable operation.
By adopting the stencil disposal sensor 53, it is possible to detect
that the stencil sheet M has been transported up to the stencil disposal rollers
39, and to detect whether or not the stencil sheet M has been transported to a
predetermined pull-in position, thereby enabling more reliable operation.
Although, in this embodiment, the stencil disposal unit 38 is adopted
in a rotary stencil printing machine in which the end of a stencil sheet M serving
as one master and fed by the stencil making section 2 is clamped, and the printing
drum 12 is rotated in the direction in which the stencil sheet M is fed in, the
stencil sheet M being then attached, it will be readily understood that the present
invention is not restricted to this application.
For example, it is alternately possible to apply the present invention
to a rotary stencil printing machine in which the rear end of a stencil sheet M
serving as one master and fed by the stencil making section 2 is clamped, and the
printing drum 12 is rotated in the direction in which the stencil sheet M is fed
in, the stencil sheet M being then attached.
Additionally, the present invention can be applied to a rotary stencil
printing machine in which both ends of a stencil sheet M serving as one master
are clamped at the printing drum 12. In a case in which both ends of the stencil
sheet M are clamped, the clamp at either end is released, thereby enabling disposal
from the released end, as described above.
Although this embodiment of the present invention is described for
the example of a rotary stencil printing machine, in which a printing section 3
has a pressure roller 16 that approaches and moves away from the printing drum
12 so as to perform printing, it will be readily understood that the present invention
is not restricted in this manner.
For example, the present invention can also be applied to a rotary
stencil printing machine having an inner pressure roller that pressing an ink-permeable
peripheral wall within the printing drum 12, and which has, instead of a movable
pressure roller 16, a pressure drum that rotates in synchronization with the printing
drum 12 at the printing drum 12.
Although the invention has been described above by reference to a
certain embodiment of the invention, the invention is not limited to the embodiment
described above. Modifications and variations of the embodiment described above
will occur to those skilled in the art, in light of the teachings. The scope of
the invention is defined with reference to the following claims.