GB2143781A - Writing instrument - Google Patents

Abstract

A multi-unit type writing instrument having a ball-point pen unit and a refill-lead type mechanical pencil unit (12) has a cam (7) rotatable with a rearward barrel (3) of a casing (1) of the instrument relative to a forward barrel thereof to selectively move a desired unit into a writing position. The cam has a projection (7e) slidable along a circumferential groove formed in the outer peripheral surface of a rearward section (11) of an inner guide sleeve (8) having a forward section (9) detachably fixed to the forward barrel. The units extend through the guide sleeve (8) for axial movement relative to the guide sleeve and are rotatable with the guide sleeve and the forward barrel. Cam followers are fixed to the units respectively and are in slidable engagement with cam surfaces (7b and 7c) so that rotation of the cam in one direction actuates a selected one of the cam followers forwardly into engagement with a notch formed in the cam at an apex thereof to hold the selected unit in its writing position. <IMAGE>

Description

SPECIFICATION Writing instrument The present invention relates to a writing instrument and, more particularly, to a writing instrument having ball-point pen unit and refill-lead type mechanical pencil unit mounted so that a desired unit can be selectively positioned into operative or writing position.

A writing instrument of the type specified above is disclosed in Japanese Laid-Open Utility Model Publication No. 38483/1983 (laid-open to public inspection on March 12, 1983) of the applicant of the present application. More specifcally, the abovementioned publication discloses a writing instrument comprising a casing including a hollow forward barel having an opening in its forward end and a hollow rearward barrel rotatable and axially movable relative to said forward barrel; a cam fixed to the inner surface of said rearwrd barrel and having two cam surfaces inclined to the axis of said casing so as to converge forwadly to a forward end; an inner guide sleeve disposed in said casing and removably fixed to said forward barrel so as to be rotatable therewith relative to said rearward barrel; a refill-lead type mechanical pencil unit including a hollow tubular lead container and a ball point pen unit, said units being both axially slidably mounted in said inner guide sleeve and adapted to be rotated therewith and with sad forward barrel relative to said rearward barrel and said cam; a circumferential groove formed in one of the outer peripheral surface of said inner guide sleeve and the inner peripheral surface of said cam; a projection formed in the other of said surfaces and engaged with said circumferential groove to guide the rotation of said cam with respect to said inner guide sleeve while preventing said cam from being axially rearwardly detached from said inner guide sleeve; cam followers respectively secured to said refill-lead type mechanical pencil unit and said ball-point pen unit adjacent the rear ends thereof and adapted to be driven axially forwardly by the action of sad cam; springs resiliently biasing said cam followers rearwardly with respect to said inner guide sleeve into contact with said cam surfaces of said cam; the rotation of said rearward barrel relative to said forward barrel causing said cam to drive a selected one of said refill-lead type mechanical pencil unit and said ballpoint pen unit so that a writing tip of the selected unit projects through said opening in said forward end of said forward barrel to a witing position; said mechanical pencil unit further including a chuck mechanism section disposed at the forward end of said lead container to grip a lead; and a knock means for forwardly actuating said lead container and said chuck mechanism section of said mechanical pencil unit when it is in its writing position so that the lead gripped by said chuck mechanism section is propelled forwardly through the writing tip of said mechanical pencil unit.

While the knock means of the writing instrument referred to above is improved over conventionally used mechanisms in that it permits a knock operation with an extremely reduced force and affords a more convenient use, this improved knock mechanism requires a large number of component parts.

Namely, this improved knock mechanism includes a knock button axially movably attached to the rear end of the rearward barrel of the casing, an axial groove formed in the outer peripheral surface of the cam so as to extend through the apex of the cam, a slide member having an elongated portion slidably received in the axial groove and movable by the knock button axially forwardly relative to the cam thereby to forwrdly push the cam follower of the refill-lead type mechanical pencil unit out of engagement with the apex of the cam, and a return spring disposed between the slide member and the cam.

The large number of parts required to form the knock mechanism not only increases the cost of manufacture thereof and thus of the writing instrument, but also has the following problem: Namely, since the knock mechanism, which consists of the many parts as pointed out above, must be accomodated by the rear end of the rearward barrel of the casing, the position of the cam is correspondingly displaced from the rear end of the toward the center of the length of the casing. Thus, it is not possible to preserve sufficiently large room or axial length for the ball-point pen unit and the refill-lead type mechanical pencil unit which must be disposed between the cam and the forwrd end of the casing. In consequence, these units are of limited lengths and thus require frequent lead-refilling operations the refill-lead type mechanical pencil unit and frequent renewals of ball-point pen units.

It is an object of the present invention to provide an improved wirting instrument of the class specified above and which eliminates the problems discussed above.

In the improved writing instrument according to the present invention, the knock means includes a recess formed in the surface in which said circumferential groove is formed, said recess being arranged and shaped such that said recess is in communication with said circumferential groove, extends axially therefrom, has circumferential and axial dimensions large enough to receive said projection and is so positioned as to be axially aligned with said projection when the forwrd end of said cam is engaged by the cam follower associated with said mechanical pencil unit whereby said rearward barrel is forwardly movable a distance together with said cam relative to said forward barrel and to said inner guide sleeve to cause said cam to axially forwardly actuate said cam follower associated with said mechanical pencil unit and said lead container for thereby axially forwardly moving said lead container and said chuck mechanism section of said mechanical pencil unit to propel the lead gripped by said chuck mechanism section.

As pointed out above, the knock mechanism of the writing instrument of the present invention does not call for any component parts which are added to the inner guide sleeve and the cam of the prior art writing instruments including the im proved writing instrument disclosed in the forementioned Japanese publication. In addition, the writing instrument of the invention has a simplified construction and, thus, can be manufactured at a reduced cost.In addition, since the circumferential groove and the projection for operatively connecting the inner guide sleeve and the cam together can be located adjacent their rear ends and since the inner guide sleeve and the cam can be disposed in the rearmost end portion of the rearward barrel of the casing due to the elimination of component parts such as the knock button and other associated members, the writing instrument of the present invention can have an increased effective length of the casing for accomodating the refilllead type mechanical pencil unit and the ball point pen unit.

A writing instrument constructed in accordance with the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is an axial sectional view of an embodiment of the writing instrument in accordance with the invention; Figure 2 is an enlarged side view of an inner guide sleeve incorporated in the writing instrument shown in Fig. 1; Figures 3 and 4 are sectional views taken respectively along lines Ill-Ill and IV-IV in Fig. 2; Figures 5 and 6 are an enlarged plan view and an enlarged side elevational view of a cam incorporated in the writing instrument shown in Fig. 1, respectively; Figure 7 is an end view of the cam taken along line Vll-Vli in Fig. 5;; Figure 8 is an enlarged fragmentary axial sectional view of the writing instrument, showing the structural relationship between the cam, cam followers, a ball-point pen unit and a refill-lead type mechanical pencil unit; Figure 9 is a sectional view taken along line IX-IX in Fig. 8; Figure 10 is an enlarged cross-sectional view taken along line X-X in Fig. 1; and Figure 11 is an axial sectional view of the writing instrument when the refill-lead type mechanical pencil unit is in the operative or writing position.

Referring first to Fig. 1, a writing instrument embodying the present invention has a casing 1 composed of a forward barrel 2 opened at its front end 2a and a hollow cap or rearward barrel 3 rotatable and axially movable relative to the forward barrel 2. In the illustrated embodiment, the forwad barrel 2 and the rearward barrel 3 respectively have rearward and forward end portions which have substantially the same diameters and are normally axially spaced by a space S formed therebetween.

The space S is covered by a ring-shaped band 4 secured to the outer peripheral surface of the forward end of the rearward barrel 3. The rear end portion of the forward barrel 2 is freely movable into and out of the band 4.

Alternatively, the rearward barrel 3 may have an outer diameter greater than that of the forward barrel 2 so that the rear end portion of the forward barrel 2 can be loosely received by the front end of the rearward barrel 3.

A clip 5 is secured to the rear end of the rearward barrel 3 by a screw 6.

A so-called "heart-shaped" cam 7, which is known per se to those skilled in the art, is secured to the inner surface of the rearward barrel 3 and movable therewith both axial and circumferential directions. The heart-shaped cam 7 is provided at its apex with a substantially V-shaped recess or notch 7a. Oblique surfaces extending rearwardly from the apex portion constitute cam surfaces 7b and 7c. Further details of the cam 7 will be described later.

Referring to Figs. 1 through 4, the casing 1 receives therein an inner guide sleeve 8 which is formed integrally by die casting. The inner guide sleeve 8 has a forward section 9 provided on the periphery thereof with a plurality of ribs 9a which fit the inner peripheral surface of the forward barrel 2 in a fixed but detachable manner, a central drum section 10 slidingly received partly in the rear end of the forward barel 2 and partly in the front end of the rearward barrel 3, and a reduced rearward section 11 having a diameter somewhat smaller than that of the drum section 10 and extending rearwardly from the drum section 10 into the rearward barrel 3 and further into the cam 7.

The forwrd section 9 and the drum section 10 have cylindrical inner surfaces as will be seen in Fig. 2. However, as shown in Figs. 3 and 4, the rearward section 11 is formed therein with a couple of axial bores lla and llb extending from th interior of the dnim section 10 to the rear end face of the section 11. These axial bores lla and llb are open in the outer peripheral surface of the rearward section 11 through axial slits lla' and llb' which are formed in the outer peripheral surface of the rearward section 11 and extend over the entire length thereof. The axial bores Ia and lib are communicated with each other through a central slit formed therebetween.

A circumferential groove Ic is formed in the outer peripheral surface of the rearward section 11 adjacent the rear end thereof. As will be seen in Fig.3, the circumferential groove llc does not completely encircle the rearward section 11 but is circumferentially interrupted by a land lid which serves as a stop for limiting the angle of rotation.

Referring now to Figs. 5 to 7, the end portion 7d of the cam 7 opposite to the apex has a hollow cylindrical form. The inner peripheral surface of the cylindrical rear end portion 7d is formed thereon with a radially inward projection 7e disposed in axial alignment with the substantially V-shaped notch 7a.

Referring then to Figs. 8 to 10, the rear end portion of the rearward section 11 of the inner guide sleeve 8 extends into the cylindrical end portion 7d through the space in the heart-shaped portion having the cam surfaces 7b and 7c and is in sliding contact with the inner surface of the cylindrical end portion 7d in such a manner as to be slidable both in axial and circumferential directions. The projection 7e on the inner surface of the cam 7 engages the circumferential groove Ic to guide the cam 7 when the cam 7 is rotated relative to the inner guide sleeve 8. The rotation of the cam 7 is stopped when the projection 7e on the cam 7 is brought into contact with one of the side edges of the land lid, as shown in Fig. 9.

The axial bores Ila and llb in the rearward section 11 of the inner guide sleeve 8 axially slidably receive, respectively, a refill-lead type mechanical pencil unit 12 and a ball-point pen unit 13, which are both of conventional structures. More specifi cally, the ball-point pen unit 13 has an ink reservoir or tube 13a filled with ink and a ball socket or writ ing tip 13b secured to the front end of the tube and provided at its forward end with a writing ball point, as shown in Fig. 1. As will be best seen in Fig. 8, the rear end portion of the ink tube 13a is detachably fitted into a retaining sleeve 13c which in turn is slidably received in the axial bore llb in the rearward section 11 of the inner guide sleeve 8.

A plug 13d is fitted into the rear end of the retain ing sleeve 13c. A cam follower 13e is secured to the outer peripheral surface of the plug 13d and projects radially outwardly through the slit llb' so that the cam follower is slidable along this slit. A tension coil spring 13f is disposed in the axial bore llb and connected at its front end 13f' to the rear end of the plug 13d. The rear end portion 13f" of the spring 13f extends slightly rearwardly from the axial bore llb and has an outer diameter greater than the inner diameter of the axial bore llb. Therefore, the spring 13f resiliently biases the cam follower 13e rearwardly into contact with the cam 7 to pull the ball point pen unit 13 rearwardly from the front end 2a of the forward barrel 2 into the casing 1.

On the other hand, the refill-lead type mechanical pencil unit 12 includes a lead reservoir or a tube 12a for refill leads and a section 12b which houses therein a known chuck mechanism (not shown) provided on the front end of the lead tube 12a. The section 12b has a forward lead protection tube 12b' through which a lead 12b" is propelled by a knock mechanism which will be discussed later. The rear end portion of the lead tube 12a is detachably fitted into a retaining sleeve 12c which in turn is slidably received in the axial bore Ila in the inner guide sleeve 8. As in the case of the retaining sleeve 13c, the retaining sleeve 12c is provided at its rear end with a plug 12d to which is secured a cam follower 12e. The cam follower 12e is slidable along the axial slit Ila' and projects radially outwardly through this axial slit Ila'.A tension coil spring 12f is disposed in the axial bore Ila and connected at its frot end 12f' to the rear end of the plug 12d. The rear end portion 12f" projects rearwardly from the rear end of the axial bore Ila and has an outer diameter greater than the inner diameter of the axial bore Ila. Therefore, the spring 12f resiliently biases the cam follower 12e into contact with the cam 7 to pull the mechanical pencil unit 12 from the front end 2a of the forward barrel 2 into the casing 1.

Since the cam followers 12e and 13e are held in contact with the cam 7 by the action of the tension coil springs 12f and 13f, the cam 7 and the rear ward barrel 3 are biased axially rearwardly with re spect to the forward barrel 2 and the inner guide sleve 8. However, the engagement between the cir cumferential groove llc and the projection 7e nor mally prohibits relative axial movement between the cam 7 and the rearward section 11 of the inner guide sleeve so that the rearward barrel 3 is prevented from being displaced rearwardly from the inner guide sleeve 8.

In the position shown in Fig. 1, the cam follow ers 13e and 12e associated with the ball-point pen unit 13 and the mechanical pencil unit 12, respectively, are held in contact with the cam surfaces 7b and 7c of the cam 7, respectively. Thus, the ball point pen unit 13 and the mechanical pencil unit 12 are both in their inoperative positions. This state will be referred to "neutral position". Then, when the rearward barrel 3 and the cam 7 are rotated with respect to the forward barrel 2 and the inner guide sleeve 8 clockwise, as viewed in Fig. 1, the cam follower 13e is moved forwardly along the cam surface 7b into the notch 7a in the forward end of the cam 7, while the other cam follower 12e is moved rearwardly along the cam surface 7c to the rear end of this cam surface.At this time, therefore, the ball-point pen unit 13 is pushed forwardly until its writing tip 13b projects to the writing position through the opening in the end 2a of the forward barrel 2 and the mechanical pencil unit 12 is simultaneously moved back from the position shown in Fig. 1 to a retracted position (these positions of the two units are not shown in the drawings).

To the contrary, if the rearward barrel 3 and the cam 7 are rotated counterclockwise with respect to the forwad barrel 2 and the inner guide sleeve 8, the cam 7 and the cam followers 12e and 13e cooperate to retract the ball-point pen unit 13 rearwardly from the position shown in Fig. 1 and advances the mechanical pencil unit 12 until the small-diameter end of the chuck mechanism section 12b and the lead protection tube 12b' of the mechanical pencil unit 12 are projected through the opening in the front end 2a of the forward barrel 2 together with the lead 12b" held by the chuck mechanism, as shown in Fig. 11. In this state, the cam followers 12e and 13e are positioned relative to the cam 7 as shown in Fig. 8.

Further details of this mechanism are not described here because a substantially identical mechanism is shown in Japanese Utility Model Publication No. 40833!1977 corresponding to U.S.

Patent No. 3,266,465 issued to W.C. Ganz August 16, 1966. Only difference is that the writing instrument disclosed in these publications has two ballpoint pen units unlike the wJiting instrument of the invention in which one of the writing units is a refill-lead type mechanical pencil.

The writing instrument of the invention is consructed and arranged to niakc a selective use of the ball-point pen unit 13 and the refill-lead type mechanical pencil 12. When the mechanical pencil unit 12 is in use in the writing position as shown in Fig. 11, the lead 12b" is gradually worn to become unusable. According to the invention, the writing instrument is provided with a knock mechanism which is operative to forwardly drive a known chuck in the chuck mechanism section 12b thereby to propel the lead 12b" forwardly from the lead protecting tube 12b'. The knock mechanism will be described hereunder.

Referring again to Figs. 2 to 4, the outer peripheral surface of the rearward section 11 of the inner guide sleeve 8 is formed in its portion adjacent the rear end thereof with a recess lle which is communicated with the circumferential groove llc and extends axially forwardly towards the drum section 10. The recess lle is bordered by one circumferential edge of the land lid and has a circumferential width large enough to receive the projection 7e of the cam 7. The depth of the recess lle measured in the radial direction of the axis of the casing 1 is equal to that of the circumferential groove llc as will be seen in Fig. 3.The axial length of the recess lle substantially corresponds to one feed of the lead 12b" by one knocking action, i.e., to one stroke of knock which in turn is equal to or somewhat smaller than the axial dimension of the space S between the forward barrel 2 and the rearward barrel 3. The position of the recess lle is determined such that the projection 7e on the inner surface of the cam 7 is axially aligned with the recess lie when the cam follower 12e associated with the mechanical pencil unit 12 is engaged by the notch 7a in the pointed end of the cam 7, as will be seen in Fig. 11.

According to this arrangement, when the mechanical pencil unit 12 is in the writing position as shown in Fig. 11, the projection 7e can be moved axially from the circumferential groove lic into the recess lle because the recess lle is in axial alignment with the projection 7e at this time. Accordingly, the rearward barrel 3 and the cam 7 can be moved axially forwardly with respect to the forward barrel 2 and the inner guide sleve 8 so that the axial movement of the cam 7 moves or knocks the cam follower 12e and the lead sleeve 12a forwardly to cause the chuck mechanism at the front end of the lead sleeve 12a to propel the lead 12b" through and out of the protecting tube 12b'.

Although a specific embodiment of the invention has been described, the described embodiment is only for the illustrating purpose and can be changed and modified within the scope of the invention. For instance, the circumferential groove lic and the recess lle can alternatively be formed in the inner peripheral surface of the cam 7 rather than in the sleeve 8 and the projection 7e on the outer peripheral surface of the rearward section 11 of the inner guide sleeve 8 rather than on the cam 7. In such an alternative case, however, the recess lle should extend axially rearwardly from the groove llc. It is also possible to modify such that the notch 7a is formed in each of the cam followers 12e and 13e rather than in the pointed end of the cam 7.

Claims (8)

1. A writing instrument comprising a casing including a hollow forward barrel having an opening in its forward end and a hollow rearward barrel rotatable and axially movable relative to said forward barrel; a cam fixed to the inner surface of said rearward barrel and having two cam surfaces inclined to the axis of said casing so as to converge forwardly to a forward end; an inner guide sleeve disposed in said casing and removably fixed to said forward barrel so as to be rotatable therewith relative to said rearward barrel; a refill-lead type mechanical pencil unit including a hollow tubular lead container and a ball point pen unit, said units being both axially slidably mounted in said inner guide sleeve and arranged to be rotated therewith and with said forward barrel relative to said rearward barrel and said cam; a circumferential groove formed in one of the outer peripheral surface of said inner guide sleeve and the inner peripheral surface of said cam; a projection formed in the other of said surfaces and engaged with said circumferential groove to guide the rotation of said cam with respect to said inner guide sleeve while preventing said cam from being axially rearwardly detached from said inner guide sleeve; cam followers respectively secured to said refill-lead type mechanical pencil unit and said ball-point pen unit adjacent the rear ends thereof and designed to be driven axially forwardly by the action of said cam; springs resiliently biasing said cam followers rearwrdly with respect to said inner guide sleeve into contact with said cam surfaces of said cam; the rotation of said rearward barrel relative to said forward barrel causing said cam to drive a selected one of said refill-lead type mechanical pen unit and said bail-point pen unit so that a writing tip of the selected unit projects through said opening in said forward end of said forward barrel to a writing position; said mechanical pencil unit further including a chuck mechanism section disposed at the forward end of said lead container to grip a lead; and a knock means for forwardly actuating said lead container and said chuck mechanism section of said mechanical pencil unit when it is in its writing position so that the lead gripped by said chuck mechanism section is propelled forwardly through the writing tip of said mechanical pencil unit, said knock means including a recess formed in said surface in which said circumferential groove is formed, said recess being arranged and shaped such that said recess is in communication with said circumferential groove, extends axially therefrom, has circumferental and axial dimensions large enough to receive said projection and is so positioned as to be axially aligned with said projection when the forward end of said cam is engaged by the cam follower associated with said mechanical pencil unit whereby said rearward barrel is forwardly movable a distance together with said cam relative to said forward barrel and to said inner guide sleeve to cause said cam to axially forwardly actuate said cam follower associated with said mechanical pencil unit and said lead container for thereby axially forwardly moving said lead container and said chuck mechanism section of said mechanical pencil unit to propel the lead gripped by said chuck mechanism section.

2. A writing instrument according to Claim 1, wherein said circumferential groove and said recess are both formed in said outer peripheral surface of said inner guide sleeve.

3. A writing instrument according to Claim 1, wherein said forward barrel and said rearward barrel respectively have rearward and forward end portions which have substantially the same diameters and are normally spaced a distance by an annular space.

4. A writing instrument according to Claim 2, wherein said forward barrel and said rearward barrel respectively have rearward and forward end portions which have substnatially the same diameters and are normally spaced a distance by an an nular space.

5. A writing instrument according to Claim 4, wherein said casing further includes an annular band secured to the forward end of said rearward barrel and covering said annular space and the rearward end portion of said forward barrel, said annular band having an inner diameter slightly greater than the outer diameter of said rearward end portion of said forward barrel.

6. A writing instrument according to Claim 3, wherein said annular space has an axial dimension substantially equal to the axial dimension of said recess.

7. A writing instrument substantially as herein described with reference to, and as illustrated by, the accompanying drawings.

8. Any new and novel feature hereinbefore described.