The invention relates to a writing instrument, particularly a ballpoint pen.

A writing instrument of said type is distributed on the market by the applicant under the term "Media Clic" and is thus a state-of-the-art device. Another writing instrument of this type is disclosed in US 5145272.

An essential function of said known writing instrument consists in that a push button is disposed in the rear portion, that is to say in the end portion of the writing instrument facing away from the writing end, and is mounted axially displaceable in the sleeve-like housing of the writing instrument so as to be secured against pivoting, on which a reservoir is supported on the reverse side by the force of a spring and by which, by manually pushing forward the push button, the reservoir can be shifted into a writing position, in which the push button is automatically latched at the housing by a latching device and is thus fixed against retraction in order to be able to perform a writing function with the writing instrument. The latching device is constituted by a zigzag-shaped guiding groove in the wall of the housing and a latch lug guided so as to be displaceable therein, which is positioned at the free end of a spring arm extending substantially parallel to the axis and mounted on the push button and which is first shifted into a peripheral direction when the push button is pushed forward in the zigzag-shaped guiding groove, and bounces back into its central position at the end of the zigzag-shaped guiding groove and latches the push button against retraction.

For releasing the latching device, a shift device is provided, which automatically unlatches the latch lug in case of further manual pushing forward of the push button out of the latching position, so that, after releasing the push button, the spring force can push the push button and the latch lug back into their original position. In order to avoid in the event of retraction from an unlatching position pushed further forwards that the latch lug reimmerses into the zigzag-shaped guiding groove and latches at its front end, what is provided at the push button is a support member having an oblique support surface, with respect to which the latch lug, when immersing into the opposed peripheral direction in the forward movement out of the latching position, is laterally displaced such that, when being moved back , the latch lug cannot bounce into its original position at the front end of the zigzag-shaped guiding groove by but only at the rear end of the guiding groove.

In the known embodiment, the support member is provided on a base of the push button, which is positioned in the central portion of the push button and forms a boundary surface for a receiving shaft for the rear end of the reservoir with its face directed forwards. This results in a difficult construction requiring high material expenditure.

The underlying object of the invention consists in improving a writing instrument of the type stated in the foregoing as far as the arrangement of the support member is concerned. What is to be done in particular is to shift the support of the support member into the peripheral portion of the push button.

Said object is solved by the features of claim 1. Advantageous further developments of the invention are described in the sub-claims.

In the writing instrument according to the invention, the support member is disposed and supported at a peripheral wall portion of the push button, which is radially outside a central free space in the push button. The support member is thus supported by a peripheral wall or a peripheral wall portion of the push button. This results in a simple shape, which can easily be manufactured particularly as an injection molded part, since no supporting wall extending transversely in the center of the push button is required, as is the case in the known configuration.

A further advantage consists in that no material is present in the central portion of the push button in the configuration according to the invention and that therefore less material is required. This also results in a reduction in weight and in production costs.

A further advantage of the embodiment according to the invention consists in that the free space can be used as receiving space for the reservoir and that therefore a cross-section greater than the cross-section of the reservoir can be designed, so that the reservoir can be inserted with play of movement. As a result, the receiving shaft for the reservoir can be axially prolonged beyond the support member, so that the writing instrument is suitable for longer reservoirs and therefore reservoirs having a greater filling for writing material and having a longer term of use can be utilized.

The support surface can be easily designed as axial transverse surface of the peripheral wall portion, which borders a hole in the peripheral wall, into which the latching lug immerses when the push button is pushed further forwards from its latching position and the latching lug immerses into the recess. What is of essential importance is that, in its immersed position, the latching lug is laterally supported towards the side on which the zigzag-shaped guiding groove is located. By said lateral support, it is prevented in a form-fit fashion that the latching lug unintentionally bounces into the guiding groove when moving back into its original position.

Moreover, the features of the sub-claims lead to simple and favorably spaced configurations both in the area of the sleeve portion supporting the supporting surface and in the area of the latching lug whose special shape ensures good operation and long lifetime in spite of unavoidable wear between the latching lug and the guiding groove.

In the following, advantageous configurations of the invention are explained in more detail by means of a preferred exemplified embodiment and drawings.

• Fig. 1 is a longitudinal sectional view of a writing instrument as claimed by the invention;
• Fig. 2 is a top view of the detail marked by X in Fig. 1;
• Fig. 3 is a top view of a push button of the detail marked by X in Fig. 1;
• Fig. 4 is the cross-sectional view IV-IV in Fig. 1.

The main components of the writing instrument marked by 1 in its entirety are a pen-shaped housing 2 and a reservoir 3 received therein.

The housing 2 consists of a grip sleeve 4 which is associated, especially screwed, at its front with a dome 5 and is closed at its rear end by a push button 6, which is associated in an axially displaceable fashion with the grip sleeve 4 by a guidance 7. The reservoir 3 is located in a reservoir shaft 8, which penetrates the dome 5 in the form of a tapered longitudinal hole 9, is constituted by the hollow space 11 of the grip sleeve 4 and extends in its rear end portion as reservoir hole 12 into the push button 6.

In the exemplified embodiment, the push button 6 has a sleeve-like guiding shaft 13, whose cross-section and e.g. circular shape is adapted with play of movement to the inner cross-sectional size and shape of the grip sleeve 4, is inserted in the grip sleeve 4 and axially displaceable therein. The reservoir 3 is biased towards the rear by a spring 14, preferably a surrounding spiral spring, its rear end portion extending into a central free space, here the reservoir hole 12 of the push button 6, and being supported towards the rear at a shoulder surface 15, which is formed in the exemplified embodiment at radial webs 16 extending radially inwards from the sleeve wall 17 of the guiding shaft 13. The reservoir 3 can also have a greater cross-section, e.g. can be adapted to the cross-section of the reservoir hole 12; the webs 16 can be missing, and a hole wall 18 bordering the reservoir hole 12 can serve as shoulder surface for support of the reservoir 3 at the back. The front end of the spring 14 is supported on the dome 5, and its rear end abuts on a shoulder in the central portion of the reservoir 3.

By manually pushing forward the push button 6, the reservoir 3 can be displaced from the represented rear parking position into a front writing position , in which the reservoir tip 3a protrudes from the dome 5 and the push button 6 is latched against retraction by a latching device 19 at the grip sleeve 4.

The latching device 19 is constituted by a latch recess 21 in the sleeve wall 22 of the grip sleeve 4 and a latch lug 23 spring-movably arranged at the push button 6, which automatically latches into the latch recess 21 on account of the elastic force of the spring. The latch lug 23 is positioned on the free end of a spring arm 24 extending approximately parallel to the axis, which is part of the push button sleeve wall 17 and is formed by wall recesses 25, 26 provided at its two sides.

The latch recess 21 is part of a zigzag-shaped guiding groove 27, whose rear groove end constitutes a parking recess 27a and whose front grove end constitutes the latch recess 21. The lateral boundary wall 21a of the latch recess 21 can be laterally displaced with respect to the boundary wall 27b of the parking recess 27a towards the guiding groove 27 by the measure a, e.g. by about one to two mm. To the front, the latch recess 21 is limited by a boundary wall 21b extending transversely, preferably at right angles, to the longitudinal axis of the grip sleeve 4.

The latch lug 23 protruding outwards from the spring arm 24 is adapted to the shape of the rear end portion or the parking recess 27a of the guiding groove 27 as far as its cross-sectional shape is concerned, i.e. it has an axial side surface 23a on the right-hand side - when seen from the back to the front -, which encloses an acute angle W1 of approximately 25° to 35° with a prolongation of the side surface 23a directed forwards and to which a free surface 23b extending at an acute angle towards the other side in the central portion of the latch lug 23 extends to a transversely extending front surface 23b, which is inclined backwards and encloses an acute angle W of e.g. approximately 45° with the longitudinal central axis 4a of the grip sleeve. The edge between the free surface 23b and the front surface 23c can be broken by a curved portion or by an edge rupture surface 23d. The back surface 23e is inclined forwards substantially parallel to the free surface 23b and terminates in a rearwards directed distance b from the front end of a sleeve wall portion 17a, which extends into the U-shaped recess 2 from the back and/or from the left-hand side in Fig. 3. In the peripheral direction directed to the right, the sleeve wall portion 17a has a support surface 17b extending parallel to the axis, which encloses an acute angle W3 with the longitudinal central plane E1 of the grip sleeve 4 extending transversely to the radial direction of movement 28 of the latch lug 23; said angle W3 can amount to approximately 30 to 60° and is about 45° in the exemplified embodiment. At the outer side, the sleeve wall portion 17a can be flattened by a secantially extending free surface 17c, with the support surface 17b being limited to the inner portion of the sleeve wall portion 17a. In the exemplified embodiment, the radially outer boundary edge 17a of the support surface 17b is approximately in the longitudinal central plane E2 extending at right angles to E1, with the latch lug 23 being displaced relative to the longitudinal central plane E2 so far outside the center - in the exemplified embodiment to the right-hand side - that it is at a radial distance c with its lower border 23f facing the longitudinal central plane E2 in its relaxed position radially above the support surfaced 17b, preferably in its central area.

From the inclined back surface 23e, the latch lug 23 has a lateral projection 23g, which is in the inner portion of its side surface above the support surface 17b and whose side surface 23h can enclose with the longitudinal central plane E2 an acute angle W4 which is open towards inside and which can be e.g. about 10 to 15°. At the upper border of the opposing side, the latch lug 23 can have a lateral projection 23a.

In the exemplified embodiment, the sleeve wall portion 17a extends in a longitudinal portion of the reservoir hole 12, whose cross-section is tapered. The difference in thickness is identified by d in Figs. 1 and 4. Therefore, the sleeve wall portion 17a projects inwards from the untapered longitudinal section of the reservoir hole 12 by the measure d. As a result thereof, a support surface 17b having a greater transverse dimension e can be achieved. In the exemplified embodiment, the sleeve wall portion 17a protrudes the longitudinal central plane E2 by the measure f.

The push button 6 is secured against pivoting by a pivot lock 31 in the grip sleeve 4 and can be displaced longitudinally in doing so. The pivot lock 31 can be put into effect by a groove/pin engagement 32 on one or on both sides between the push button 6 and the grip sleeve 4. In the exemplified embodiment, what projects from the push button 6 on both sides are guiding webs 33ab, which extend parallel to the axis, which are located in the inner wall surface of the sleeve wall 22 in guiding grooves 34 extending in parallel with play of movement and which are open on the reverse side, so that the push button 6 can be inserted with the guiding webs 33 from behind. Thereby, it is ensured that the latch lug 23 is positioned in the peripheral directions with respect to the guiding groove 27.

The latching device 19 is combined with a shift device 35, which enables that the latching device 19 is released and the push button 6 is retracted with the reservoir 3 from the latching position into the parking position. For performing said releasing step, the push button is pushed forwards manually from the latching position, the latching lug 23 hitting against the boundary wall 21b with its front surface 23c and thus being moved radially inwards; in doing so, it impinges upon the laterally effective support surface 17b and is displaced there towards the side facing away from the guiding groove 27 far enough to be on a line parallel to the axis, which is beside the latch recess 21, so that, when the push button 6 is moved back by the force of the spring 14, the latch lug 23 is guided beside the latch recess 21 at the inner surface of the sleeve wall 2 and reaches the parking position without immersing into the latch recess 21, in which position it bounces back into the parking recess 27a. The line 36 extending parallel to the axis cuts the parking recess 27a and the latch lug 23 centrally, so that it is ensured that the latch lug 23 bounces in automatically.

It is also possible to arrange the support surface 17b such that the latch lug 23 automatically bounces into the area of the line 36 due to the lateral bending out of the spring arm 24 by the displacement a when pushing forward the push button and immersing the latch lug 23. The support surface 17 can be arranged in a position so as to prevent lateral movement of the latch lug 23 towards the latch recess 21 by a stop, when the push button 6 is moved back into the parking position from the pushed forward position.