GB2053803A - Retractable mechanism for writing instrument and such instruments - Google Patents

Abstract

A writing instrument of the kind having a pivoted latch 7 actuated by a plunger 4 is assembled with the latch and plunger in one, preferably injection moulded, piece, with frangible ligand portions 51 between the plunger and latch. The first depression of the plunger breaks the ligand portions and separates the plunger and latch. <IMAGE>

Description

SPECIFICATION Retractable mechanism for writing instrument and such instruments This invention relates to retractable mechanisms for writing instruments and such instruments.

In co-pending application U.K. Patent Application No. (our ref. 27374) there is a discussion of a prior art retractable mechanism disclosed in U.K.

Patent No. 804,903 and there is disclosed a retractable mechanism.

The above mentioned co-pending application discloses and claims a retractable mechanism for a writing element comprising a plunger, a passage means defining a passage in which said plunger is constrained to move in the longitudinal direction of said passage, a pair of latch means oppositely disposed when viewed in a plane normal to said longitudinal direction, a latch member reciprocally displaceable in said longitudinal direction by means of said plunger, said latch member having a pair of laterally extending latch arms oppositely directed and each disposed for engagement with a respective one of said latch means, one of the latch means defining a forward, projected position of the writing element and the other of the latch means defining a rearward, retracted position of the writing element, when present the writing element is resiliently biased to urge the latch member rearwardly in its longitudinal direction to ensure that one of said latch arms engages with its associated latch means, advance of the plunger in the forward longitudinal direction releasing the engaged one of the latch arms from its latch means, whereby the latch member may be displaced laterally to ensure align mentofthe other of said latch arms with its associated latch means thereafter to engage therewith whereby the writing element may be displaced between its retracted and projected positions (or vice versa) in response to successive depressions of the plunger characterised in that the latch member has a rearwardly extending limb with opposite faces configured for linear contact with continguous portions of the passage interior walls, the plunger contacting the rearward end of the rearward limb on each successive depression thereof, the latch member having fulcrum means at a forward portion thereof for engagement with the writing element (when present), wherein, in use, depression of the plunger advances the latch member with its rearward limb in sliding contact with the passage interior wall contiguous with the last engaged latch arm whereby the resultant of the depression force on the plunger and the resilient bias on the writing element laterally displaces latch member such that the latch arm remote from the last engaged latch means is longitudinally aligned with its associated latch means, and thereafter release of the plunger enables the now aligned latch arm and latch means to engage followed by rocking for the latch member about its fulcrum means to place a respective face of the rearwardly extending limb of the latch member in linear contact with that portion of the passage interior wall contiguous with the now engaged latch means, thereby positioning the rearwardly extending limb of the latch member in readiness for the next depression of the plunger.

In the same application it is a preferred feature that each latch means and its associated latch arm have co-operating means to facilitate a pivot action therebetween, and wherein when, following depression of the plunger to release the last engaged latch arm, the latch member is urged rearwardly then the respective one of the faces of the limb moves rearwardly in sliding contact with the co-operating means of a latch means thereby laterally positioning the latch member such that the resilient bias acting on the writing element is effective to cause said pivot action between the now engaged latch arm and latch means.

In one preferred embodiment, the fulcrum means of the latch member comprises pivot means for pivotal contact with one end of the writing element.

Alternatively, the latch member may be provided with a recess, suitably one with inner faces defining a dihedral angle, which will receive one end of the writing element to facilitate pivotal action between the latch member and the writing element.

This co-pending application also discloses a writing instrument, more particularly a ballpoint pen, incorporating the retractable mechanism.

This present application seeks to modify the above defined retractable mechanism in a manner which facilitates incorporating the mechanism in a writing instrument in an automated assembly situation.

In this context, the present invention seeks to reduce the number of individual components of the pre-assembled retractable mechanism to a minimum and to provide for a simple assembly of the retractable mechanism perse which is effected prior to assembly of the writing instrument and which facilitates the insertion of the complete retractable mechanism into a part of the writing instrument as a single step in the assembly of the writing instrument.

Accordingly, the present invention provides a retractable mechanism for a writing element and as previously defined herein, wherein the passage defining means and latch means are integrally formed and the plunger and latch member are integrally formed with a ligand or ligands connecting them, said ligand(s) being capable of rupture on actuation of the retractable mechanism by depression of the plunger in an assembled writing instrument.

In a preferred embodiment, an end of the plunger which co-operates with the latch member includes a groove and the latch member is formed with a stop member which, in use, traverses the groove and retains the latch member in mechanical co-operation with the plunger.

Also in a preferred embodiment, the plunger member and a wall portion of the passage have co-operating means to limit the movement of the plunger in the longitudinal direction of the passage thereby in the assembled mechanism to retain the plunger in the passage.

In the preferred embodiment, the passage defining means defines a housing for the plunger into which the integral plunger and latch member are inserted through an open face in the passage defining member, said open face extending between wall portions of the passage, which wall portions each terminate with a respective one of the latch means.

In the preferred embodiment the ligands extends between a limb of the latch member, which limb carries the stop member, and a flexing portion on the passage defining means, the latch member being so disposed relative to the flexing portion that, on rupture of the ligand(s), the stop member is directed through an opening therefor into said groove and thereafter the stop member is retained in the groove.

There is also provided a writing instrument incorporating this retractable mechanism, wherein the casing of the writing instrument comprises a hollow casing member including biasing means biasing the writing element into its retracted position, a closure member adapted to be connected to the casing member and configured to receive the integral passage defining means and latch means therein, the passage defining means also defining a cavity for the latch member.

The preferred retractable mechanism is assembled simply by positioning the combined plunger and latch member in the passage defining means with the co-operating means of the plunger and passage wall portion in register. Thereafter, the assembled retractable mechanism is inserted into the closure member of the writing instrument which itself is then connected to the casing member of the writing instrument, the casing member already having the writing element and its biasing means therein. Thus, assembly is reduced to three steps, which are capable of automated operation, namely insertion of the plunger into the passage defining means, insertion of the passage defining means into the closure member and connection, e.g. threaded connection of the closure member to the casing member containing the resiliently bias refill.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a writing instrument incorporating a retractable mechanism according to the invention; Figure 2 shows the integral passage defining means and stop means; Figure 3 shows the integral plunger and latch member as formed; Figure 4 shows in perspective the retractable mechanism assembled; and Figures 5A and 5B show views of the latch member in the assembled retractable mechanism in its advanced and retracted positions.

Awriting instrument incorporating a retractable mechanism in Figure 1 which is an elevational view, partly in section of a ballpoint pen. The pen has a hollow casing 31 which is provided at its forward end 32 with an internal shoulder 33 and a bore 34 of reduced diameter with respect to the hollow interior 19 of the casing 31. The bore 34 is of a suitable diameter for a ballpoint refill 36 to be slidingly displaced therein for the purpose of displacing a tip portion 35 between its retracted position and its advanced writing position.

The refill 36 is resiliently biased towards its retracted position by means of a spring 37 which bears upon the shoulder 33 and a crimp 38 on the refill 36. The refill 36 is restrained from further displacement towards the top of the casing 31 by contact with a pivot edge 9 on a latch member 7 of the retractable mechanism. The retractable mechanism will be described below. The casing 31 is provided with a hollow closure member 39 which is threadedly connected thereto at 40. The plunger 4 of the retractable mechanism is located in a passage 3 of the closure member 39 and is retained within the passage 3 (see Figure 2).Assembly of the ballpoint pen requires the spring 37 and refill 36 to be placed in the casing 31, the plunger 4to be arranged in the closure member 39, then the latch member 7 to be placed in the passage 3 and finally the casing member 31 and closure member 39 to be threadedly connected together. Provided that the refill is set at or nearthe axis of the casing 31, an initial full depression of the plunger 4 will ensure that the pivot edge 9 rests on the upper edge 10 of the refill 36.

Reference is now also made to Figures 2 to 5A and B. The retractable mechanism for the refill 36 advances and retracts the refill on actuation of plunger 4. Passage defining means 2 define a passage 3 in which a plunger 4 is constrained to move in the longitudinal direction of the passage 3.

A pair of latch means 5,6 are oppositely disposed, when view in a plane normal to the longitudinal direction of passage 3: as will become clear the latch means 5,6 determine advanced and retracted positions of the writing element 1. A latch member 7 is reciprocally displaceable in the longitudinal direction of passage 3 by means of the plunger 4. Latch member 7 has one end 8 defining a pivot edge 9 for engagement with the end face 10 (Figure 1) of the refill 36. A pair of latch arms 11, 12 extend laterally of the latch member7 in opposite directions and each of the latch arms 11, 12 is disposed for engagement with an associated one of the latch means 5,6.

The refill 36 is resiliently biased as described, in the direction of arrow A two urge the latch member 1 in said longitudinal direction until one of the latch arms 11,12 contacts its associated latch means 5,6.

As shown in Figure 1 latch arm 11 contacts latch means 5. The plunger 4 may be advanced against the bias acting on the latch member 7. From the position shown in Figure 1 an actuating advance of the plunger4causesthe latch memberto be angularly displaced about its pivot edge 9 and about its position of contact with the plunger 4 to the extent necessary for the other of the Itch arms 12 to be aligned with its associated latch means 6. Retraction of the plunger 4 (after an actuating advance thereof) allows the latch arm 12 so aligned to engage its associated latch means 6. This engagement between latch arm 12 and latch means 6 is maintained until a further advance of the plunger 4 is effected.

In this embodiment it is a preferred feature that each latch means 5,6 and its associated latch arm 11,12 is configured to facilitate a pivot action there between. After the plunger 4 is retracted, under the influence of the bias acting on latch member 7, to the extent that one of the latch means 6 engages its associates latch arm 12, pivot action of the latch member 7 is initiated and continues until the latch member 7 abuts that portion 14 of the passage 3 contiguous with the latch means 6 (Figures 5B). In this embodiment, the latch means 5,6 each define a pivot edge 15 and the latch arms 11,12 each define a notch 16 for line contact with the respective pivot edge 15 about which line contact the pivot edge 15 executes this pivot action.

As shown in Figure 2 the passage defining means 2 and the latch means 5,6 are integral and form part of a casing for the retractable mechanism. The latch arms 5,6 are arranged at laterally opposite and axially spaced locations at the end 17 of the passage 3 communicating with the latch member 7. The latch member 7 alternately contacts (Figures 5A and 5B) opposite portions 13, 14 of the passage 3 contiguous with respective ones of the latch means 5,6 according to which of its latch arms 11,12 is engaged with a latch means 5,6.

The general operation of the retractable mechanism in transferring the refill 36 between the advanced position of the member in Figure 5A and the retracted position of the member in Figure 5B (and vice versa) has been described with respect to the drawings of the previously mentioned U.K. Patent Application No. (Our Ref. 27374).

The manner in which the structure of the present retractable mechanism differs from that of these earlier applications will now be described. As shown in Figure 3, the plunger 4 and latch member 7 are integrally formed with two thin ligands 51 connecting them. The ligands 51 are capable of rupture on actuation of the plunger 4 in an assembled writing instrument. The plunger 4, latch member 7 and ligands 51 may be injection moulded from a suitable thermoplastics material such as General Purpose Polystyrene.

One end of the plunger 4, which co-operates with the latch member 7, includes a groove 52 and the latch member is formed with a stop member 53 which, in use, traverses the groove 52 and retains the latch member 7 in mechanical co-operation with the plunger 4.

The plunger 4 and a wall portion 13 of the passage 3 have co-operating means namely recess 54 (Figure 3) and abutment 55 (Figure 2), to limit the movement of the plunger 4 in the longitudinal direction of the passage 3 thereby in the assembled mechanism to retain the plunger 4 in the passage 3. The passage defining means 2 also includes a cavity 19 for the latch member 7.

As shown in Figures 2,4, so and 5B the passage defining means 2 defines a housing for the plunger 4 into which the integral plunger 4 and latch member 7 are inserted through an open face in the passage defining member 2, said open face 56 extending between wall portions 13,14 of the passage 3. The wall portions 13,14 each terminate with a respective one of the latch means 5,6.

As shown in Figure 3, the ligand or ligands 51 extend between a limb 23 of the latch member 7, which limb 23 carries the stop member 53, and the flexing portion 59 on the plunger 4. The latch member 7 is so disposed relative to the flexing portion 59 that, on rupture of the ligands 51, the stop member 53 is directed through an opening 57 therefor into said groove 52 and thereafter the stop member 53 is retained in the groove 52. The material of the plunger 4 is sufficiently flexible that the opening 57 may be slightly undersized with respect to the stop member 53. Flexing portions 58,59 of the plunger 4, which define the opening 57, deflect to allow the stop member 53 to enter the groove 52.

Once the flexing portions 58,59 resume their normal attitude, stop member 53 is retained within groove 52. Portions 58,59 are contiguous with the groove 52 and opening 57. When the casing 31 and closure member 39 (Figure 1) of the writing instrument are separated for the purpose of changing the refill 36, the stop member 53 retains the latch member7 in the closure member 39.

The retractable mechanism is assembled simply by positiooning the combined plunger 4 and latch member 7 (of Figure 3) in the passage defining means 2 (Figure 2) with the co-operating means 54,55 of the plunger4 and passage wall portion 13 in register (Figure 4). Thereafter, the assembled retractable mechanism is inserted into the closure member 39 of the writing instrument which itself is then connected to the casing member 31 of the writing instrument. The passage defining means 2 may be a force fit or other means may be provided to ensure its retention. The casing member 31 will already have the writing element 36 and its biasing means 37 therein. Thus, assembly is reduced to three steps, which are capable of automated operation, namely insertion of the plunger 4 into the passage defining means 2, insertion of the passage defining means 2 into the closure member 39 and connection, e.g.

threaded connection of the closure member 39 to the casing member 31 containing the resiliently biased refill 36.

Turning to Figurs 5A and 5B the advanced and retracted positions of the latch member 7 are shown and these correspond to the advanced and retracted positions of the refill 36 of the writing instrument of Figure 1. As already stated, the retractable mechanism operates as described in the previously mentioned U.K. Patent Application.

Claims (9)

1. A retractable mechanism for a writing element comprising a plunger (4), a passage means (2) defining a passage (3) in which said plunger (4) is constrained to move in the longitudinal direction of said passage (3), a pair of latch means (15) oppositely disposed when viewed in a plane normal to said longitudinal direction, a latch member (7) reciprocally displaceable in said longitudinal direction by means of said plunger (4), said latch member (7) having a pair of laterally extending latch arms (11,12) oppositely directed and each disposed for engagement with a respective one of said latch means (5 or 6), one of the latch means (6) defining a forward, projected position of the writing element (1) and the other of the latch means (5) defining a rearward, retracted position of the writing element (1), when present the writing element (1) is resiliently biased to urge the latch member (7) rearwardly in its longitudinal direction to ensure that one of said latch arms (11,12) engages with its associated latch means (5,6), advance of the plunger (4) in the forward longitudinal direction releasing the engaged one of the latch arms (11) from its latch means (5,6) whereby the latch member (7) may be displaced laterallyto ensure alignment of the other of said latch arms (12) with its associated latch means (6) thereafter to engage therewith whereby the writing element (1) may be displaced between its retracted and projected positions (or vice versa) in response to successive depressions of the plunger (4) characterises in that the latch member (7) has a rearwardly extending limb (23) with opposite faces (21,22) configured for linear contact with contiguous portions (13,14) of the passage interiorwalls (2), the plunger (4) contacting the rearward end of the rearward limb (23) on each successive depression thereof, the latch member (7) having fulcrum means (9) at a forward portion (8) thereof for engagement with the writing element(1) (when present), wherein, in use, depression of the plunger (4) advances the latch member (7) with its rearward limb (23) in sliding contact with the passage interior wall contiguous (13 or 14) with the last engaged latch arm (11 or 12) whereby the resultant (F) of the depression force (B) on the plunger (4) and the resilient bias (A) on the writing element (1) laterally displaces latch member (7) such that the latch arm (12 or 11) remote from the last engaged latch means (5,6) is longitudinally aligned with its associated latch means (5,6), and thereafter release of the plunger (4) enables the now aligned latch arm (12 or 11) and latch means (5,6) to engage followed by rocking for the latch member (7) about its fulcrum means (9) to place a respective face (22 or 21) of the rearwardly extending limb (23) of the latch member (7) in linear contact with that portion (14 or 13) of the passage interior wall (2) contiguous with the now engaged latch means (5,6) thereby positioning the rearwardly extending limb (23) of the latch member (7) in readiness for the next depression of the plunger (4), wherein the passage defining means (2) and latch means (5,6) are integrally formed and the plunger (4) and latch member 7 are integrally formed with a ligand or ligands (51) connecting them, said ligand(s)(51) being capable of rupture on actuation of the retractable mechanism by depression of the plunger in an assembled writing instrument.

2. A retractable mechanism as claimed in Claim 1, wherein each latch means (5,6) and its associated latch arm (11,12) have co-operating means (15,16) to facilitate a pivot action therebetween, and wherein when, following depression of the plunger (4) to release the last engaged latch arm (11,12), the latch member (7) is urged rearwardlythen the respective one of the faces (21,22) of the limb (23) moves rearwardly in sliding contact with the co-operating means (15) of a latch means (5,6) thereby laterally positioning the latch member (7) such that the resilient bias (A) acting on the writing element (1) is effective to cause said pivot action between the now engaged latch arm (11 or 12) and latch means (5 or 6).

3. A retractable mechanism as claimed in either Claim 1 or Claim 2, wherein an end of the plunger (4) which co-operates with the latch member (7) includes a groove (52) and the latch member (7) is formed with a stop member (53) which, in use, traverses the groove (52) and retains the latch member (7) in mechanical co-operation with the plunger(4).

4. A retractable mechanism as claimed in Claim 3, wherein the plunger (4) and a wall portion (13) of the passage (3) have co-operating means (54,55) to limit the movement of the plunger (4) in the longitudinal direction of the passage (3) thereby in the assembled mechanism to retain the plunger (4) in the passage (3).

5. A retractable mechanism as claimed in any one of Claims 1 to 4, wherein the passage defining means (2) defines a housing for the plunger (4) into which the integral plunger (4) and latch member (7) are inserted through an open face (56) in the passage defining member (2), said open face (56) extending between wall portions (13, 14) ofthe passage (3), which wall portions (13, 14) each terminate with a respective one of the latch means (5,6).

6. A retractable mechanism as claimed in any one of Claims 1 to 5, wherein the ligand(s) (51) extends between a limb (23) of the latch member (7), which limb (23) carries the stop member (53), and a flexing portion (59) on the plunger (4), the latch member (7) being so disposed relative to the flexing portion (59) that, on rupture of the ligand(s) (51), the stop member (53) is directed through an opening (57) therefor into said groove (52), and thereafter the stop member (53) is retained in the groove (52).

7. Awriting instrument incorporating a retractable mechanism as claimed in any one of Claims 1 to 6, wherein the casing of the writing instrument comprises a hollow casing member (31), including biasing means (37) biasing the writing element (1) into its retracted position, a closure member (39) adapted to be connected to the casing member (31) and configured to receive the integral passage defining means (3) and latch means (5,6) therein, the passage defining means (2) also defining a cavity for the latch member (7).

8. A retractable mechanism for a writing element member arranged, constructed and adapted to operate substantially as hereinbefore described with reference to Figures 2 to 4 of the accompanying drawings.

9. Awriting instrument incorporating a retractable mechanism for the writing element, arranged, constructed and adapted to operate substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings.