DUAL REFILL WRITING UTENSIL

Abstract: A writing utensil with dual refills is described, which when a cap (3) on a body (1), is rotated in one direction or the other, first and second refills (4, 5) are alternately projected and retracted from the body (1), whereby either the first or second refill can be held at an operating position whilst the other is withdrawn.

Description: This invention relates to a dual refill-type writing utensil. A conventional dual refill writing utensil is described in US-A-4,227,822. The writing utensil has a column or guide post connected to the top end of a lower outer cylinder or body, while sliders on a mechanical pencil holder and a ball point pen-holder are slidable in axially grooves on the guide post. A cam cylinder is fitted into an upper outer cylinder cap and these are slidable and rotatably secured to the guide post, so that a cam surface of the cam cylinder can engage the sliders on the mechanical pencil holder and ball point pen-holder. The mechanical pencil holder and the ball point pen-holder are alternately projected and retracted from the lower end of the body upon rotation of the cap by means of the incorporated cam cylinder engaging and urging each slider, and associated refill. In this conventional writing utensil, the sliders can easily slip out from the axially grooves because of rotational friction (rotational load), and thus the sliders are not smoothly slid upon rotation of the cam cylinder. As a result, the alternate projection and retraction of the mechanical pencil holder and the ball point pen-holder cannot be smoothly accomplished. The formation of the guide post with a columnar shape, results in a large diameter or cap, so that the whole construction of the writing utensil becomes large. In such a conventional writing utensil, since a separate cam cylinder is required, the number of parts is large, the construction of the writing utensil is complicated and expensive, assembly of the parts is complicated, so that productivity of the utensil is reduced. Furthermore in such a conventional writing utensil, because the cam cylinder and guide post are separately constructed, they have to be precisely concentrically assembled. This increases the cost of manufacture while decreasing productivity. Also, the cam cylinder plays easily with respect to the guide post, when rotated or moved axially, so that the cam cylinder cannot be smoothly operated. Fir this reason, the mechanical pencil holder and ball point pen-holder cannot alternately be projected and retracted smoothly, so that the function ability of the writing utensil deteriorates. The most relevant know prior art is described in GB-A-2143781 and includes structures corresponding to those mentioned in the pre-characterising part of claim 1 of this document. The present invention seeks to provide a writing utensil of simplified construction in order to be able to enhance productivity and diminish cost. The present invention seeks to provide a writing utensil with refills each having a slider which can be slide reliably, axially in the utensil to project or retract the associated refill. The present invention seeks to provide a writing utensil of compact and efficient construction. According to the present invention there is provided a writing utensil comprising: a tubular body; a guide post detachably fitted to one end of the tubular body; a hollow cap rotatably secured to the body by means of the guide post; first and second axially displaceable sliders received into said cap and prevented from rotation around the longitudinal axis of the utensil by said guide post, each of said sliders mounting a refill writing element and cam means arranged to displace said sliders upon relative rotation of the body and the cap in order to selectively project one of said writing elements and retract the other a shaft engagement portion formed at the rear end of the guide post, remote from the body, the shaft engagement portion being divided in the diametric direction to provide resiliently deformable locking claws adapted to engage in a shaft insert hole formed in the cap whereby the cap is secured to the body; the shaft insert hole being formed near to an open end of the cap, said end being adapted to securely receive a top machine screw characterised in that the top machine screw has a thrust shaft portion arranged to engage between the locking claws and thereby prevent the locking claws from disengaging the shaft insert hole. Preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 is a section through a writing utensil according to an embodiment of the present invention; Figure 2 is a sectional view taken along the line II-II of Figure 1; Figure 3 is a sectional view taken along the line III-III of Figure 1; Figure 4 is an enlarged front view of a guide post; Figure 5 is a side view of Figure 4; Figure 6 is a bottom plan view of Figure 4; Figure 7 is a sectional view taken along the line VII-VII of Figure 5; Figure 8 is a sectional view taken along the line VIII-VIII of Figure 5; Figure 9(A) is a sectional view showing a rearward outer cylinder; Figure 9(B) is a sectional view taken along the line IX-IX of Figure 9(A); Figure 10 is a sectional view taken along the line X-X of Figure 9(A); Figures 11(A) and (B) are views illustrating different modifications of a cam engaging projection; Figure 12 is a front view, partly in section, showing internal construction of the writing utensil; Figure 13 is an enlarged sectional side view of Figure 4 of the upper part of the writing utensil; Figure 14 is a sectional view taken along the line Y-Y of Figure 12; Figure 15 is a sectional side view showing the writing utensil according to another embodiment of the present invention; Figure 16 is a side view of an internal mechanism of the writing ustensil of Figure 15; Figure 17 is an enlarged plan view showing a guide post; Figure 18 is a sectional view taken along the line I-I of Figure 17; Figure 19 is a sectional view taken along the line II-II of Figure 15; Figure 20 is an explanatory view showing a mechanism for restricting a rotation of a cap of the writing utensil; Figure 21 is an explanatory view similar to Figure 20; Figure 22 is a partly sectional view showing a pen holder; Figure 23 is a sectional view taken along the line III-III of Figure 15; Figure 24(A) is a front view showing a slider; Figure 24(B) is a side view of Figure 24(A); Figure 25 is a front view of a cam cylinder; Figure 26 is a sectional view taken along the line IV-IV of Figure 25; Figure 27 is a sectional view taken along the line V-V of Figure 26; Figure 28 is a developed explanatory view illustrating functions of a cam cylinder; Figure 29 is a view, on the same section as that of Figure 23, showing another example of a slider; Figure 30 is a side view showing a guide port modified in respect of a mechanism for restricting a transfer of a cam cylinder; Figure 31 is a front sectional view of Figure 30; Figure 32 is a sectional view taken along the line VI-VI of Figure 30; Figure 33 is a front view showing a cam cylinder modified in respect of the mechanism for restricting a transfer of a cam cylinder; Figure 34 is a sectional view taken along the line VII-VII of Figure 33; Figure 35 is a sectional view taken along the line VIII-VIII of Figure 34; Figure 36 is a developed explanatory view illustrating functions of the cam cylinder of Figure 33; Figure 37 is a developed view showing another cam cylinder modified in respect of the mechanism for restricting a transfer of the cam Figure 38 is a sectional view of a writing utensil showing yet another modification of the mechanism for restricting a transfer of the cam cylinder; Figure 39 is a sectional view showing the guide post of Figure 38 Figure 40 is a plan view illustrating a state in which a cam cylinder is fitted into the guide post of Figure 39; Figure 41 is a sectional view taken along the line X-X of Figure 39; Figure 42 is a sectional view showing the cam cylinder of Figure 38; Figure 43 is a sectional view taken along the line XI-XI of Figure 42; Figure 44 is a front view of a cam cylinder showing another example of the mechanism for restricting a transfer of the cam cylinder; Figure 45 is a developed explanatory view illustrating functions of the cam cylinder of Figure 44; Figure 46 is a longitudinal sectional view showing another modified writing utensil; Figure 47 is a sectional view showing the upper part of the body of the writing utensil of Figure 46; Figure 48 is a front view showing the sheath of Figure 46; Figure 49 is a side view, partly in section, showing a modification of the writing utensil of the Figure 1 embodiment; Figure 50 is an enlarged sectional side view of the upper part of the modified writing utensil of Figure 49, from the side of the mechanical pencil holder; and Figure 51 is an enlarged sectional view of the cap of Figure 49 viewed from the side of the ball point pen-holder. A first embodiment of the present invention will be described with reference to Figures 1 to 14 of the drawings. Referring to Figure 1, a writing utensil comprises a lower outer cylinder or hollow body part 1, a guide post 2 mounted on the upper end of the body 1; an upper outer cylinder or cap 3 rotatably attached to guide post 2, which cap 3 is axially slidable by a knocking operation, and two refills 4, 5 slidably guided in guide post 2, and each carrying a slider 6,7 which has cam surface 61, 71, which can engage with a projection 34 on the inside of cap 3. The lower end of guide post 2 is cylindrical and, as is shown in Figures 4 to 8, has, sequentially; on threaded portion 20 by which the lower end of post 2 is screwed in to an internal threaded portion 10 at the upper end of the body 1; a projecting annular portion 21, a lower face of which abuts against the top end of body and the outside diameter of which is substantially the same as outside diameter of the body 1; and a cylindrical portion 22 of a smaller diameter than annular portion 21. The cylindrical portion 22 has substantially the same outside diameter as threaded portion 20. Further the post 2 has a rectangular sectioned shaft portion 23 integrally with, and projecting from the upper end of the cylindrical portion 22 in a coaxial manner. An integral cylindrical portion 24 surmounts the upper end of the guide shaft portion 23, in a coaxial manner, and an integral upper engagement shaft portion 25 extends co-axial from and is smaller in diameter than upper cylindrical portion 24. The engagement shaft portion 25 is forked, and has locking claws 25a. Also in post 2, two slide holes 26 and 27 extend through the externally threaded portion 20 and the annular portion 21 at the symmetrical positions with respect to the center of the shaft 23, to cut-away parts 22a,b of cylindrical portion 22, as shown in Figure 6 and 7. A rotation-stop 28 projects radially from annular portion 21, and which restricts the range of relative rotation cap 3 as will be described hereinafter. The rotation-stop 28 is accommodated in a large internal diameter portion 30 at the lower end of cylindrical cap 3. As best seen in Figures 9a and b, and 10 on the inside surface of cap 3, are a pair of parallel axial slide grooves 31 and 32 the lower ends of which open on to the upper end of the large internal diameter portion 30, and which permit a knocking operation of the cap 3, as will be explained hereinafter. Moreover, an extreme end portion 33 of a partition wall between these axial slide grooves 31 and 32 forms a rotation-stop 33, extending from a step 30a into the large internal diameter portion 30 of cap 3. In use, the rotation-stop 33 can abut against either side of rotation-stop 28 on post 2, to restrict rotation of cap 3, about guide post 2. Under such conditions of restricted rotation, when stop 33 abuts rotation-stop 28, the upper end of rotation-stop 28 is opposite to the lower, open end of one of the axial slide grooves 31 and 32. As a result, rotation-stop 28 can enter into either of axial slide grooves 31 and 32 to permit cap 3 to advance by a knocking operation. As will become apparent, the axial length of the axial slide grooves 31 and 32, i.e. each distance (a) defined between the step 30a, portion 30, and the upper end of the axial slide grooves 31 and 32, corresponds to a knocking margin for sending out a lead in mechanical pencil holder 4. Thus, the cap 3 can be downwardly transferred by the distance (a) to allow a knocking operation. It is to be noted that where only one of the two refills is a mechanical holder, only one of the axial slide grooves 31 and 32 need be provided for knocking the mechanical pencil holder. The provision of two grooves allows for the utensil to be used with two mechanical pencil holders. It will become apparent when the stop 33 is positioned opposite to stop 28 by rotation of the cap 3, the mechanical pencil holder 4 and the ball point pen-holder 5 are retracted, and held contained in the utensil. In that situation, the step 30a of portion 30 abuts against the upper end of stop 28, so that cap 3 cannot advance. Thus, stop 28 prevents the cap 3 from a play the axial direction. A cam engaging projection 34 for engaging cam surfaces 61 and 71 of sliders 6 and 7 (see Figures 1, 3, 9(A) and 10) extends from midway to the top end on the inside of the cap 3. The cam engaging projection 34 is diametrically opposite stop 33 on the inside of cap 3, as shown in Figure 9(A) and Figure 10. The end of cam engaging projection 34 is formed into a suitable profile, which can move and engage smoothly with the respective cam surfaces 61 and 71 of sliders 6 and 7, for example the profile may be a sharply tapered one as shown in Figure 11(A), a round one is shown in Figure 11(B), or the like figure. Towards the upper end of cap 3 is a small diameter shaft insert hole 35, and an internally threaded portion 36 above shaft insert hole 35. The refills 4, 5 illustratively a mechanical pencil holder 4 and the ball point pen-holder 5, are inserted into the slide holes 26 and 27 of guide post 2, respectively, to be axially slidable. As shown in Figure 12, mechanical pencil holder 4 has a lead guide 41 detachably connected to the lower end of a lead pipe 40, which is inserted into one (26) of the slide holes. Accordingly, if the lead pipe 40 is pulled out from the lead guide 41 after removing the guide post 2 from the body 1, required leads can be inserted in lead pipe 40. In such mechanical pencil holder 4, a lead feeding mechanism 42 is disposed on the lower end of the lead guide 41. The lead feeding mechanism 42 comprises a lead chuck 43, a chuck fastening ring 44, and a first spring or elastic member 45 as a cushioning means. On the other hand, the ball point pen-holder 5 is detachably connected to the lower end of a pen attaching shaft 50 which is inserted slidably in the other slide hole (27) through a pen-holder 51. The pen-holder 51 has a small diameter cylindrical portion 51A with which can receive lead pipe 40 of mechanical pencil holder 4, and a larger diameter cylindrical portion 51B which can receive the end of ball point pen-holder 5, so that either can be detachably connected. Accordingly, interchangeability of the refills is obtained so if ball point pen-holder 5 is pulled out from the cylindrical portion 51B, a separate mechanical pencil holder having a different lead diameter or type from that of the mechanical pencil holder 4 can be fitted to the small diameter meshing cylindrical portion 51A. The sliders 6 and 7 are connected to the respective upper ends of mechanical pencil holder 4 and ball point pen-holder 5, respectively. These sliders 6 and 7 are generally semi-cylindrical, as shown in Figures 2, 3 and 14, with a rectangular groove 60, 70 on their flat face and when put together they form a generally circular-shaped whole, with the axial grooves 60 and 70 on the inside, see e.g. Figure 14. The cam surfaces 61 and 71 on the outside of slides 6 and 7, are gradually curved and inclined from the lower end of each slider towards the top, and so that with slides together they symmetrical. At the top end each cam surfaces 61 and 71 has locking portions 61a and 71a, as shown in Figures 1 and 14, which have a concave profile, matching the shape of the cam engaging projection 34. The axial grooves 60 and 70 of slides 6 and 7 embrace shaft portion 23, so that sliders 6 and 7 can be individually axially slide along the shaft 23, together with the mechanical pencil holder 4 or ball point pen-holder 5, respectively. An elastic members in the form of spring 46 and 52 is interposed between the top of the cylindrical portion 21 of the guide post 2 and the under side of the respective slider 6, 7 to urge the mechanical pencil holder 4 and ball point pen-holder 5 upwards. As a result, the tops of the sliders 6 and 7 abut against the underside of the upper circular portion 24 at the top of shaft 23, which limits upward movement of the sliders. To assemble the writing utensil, the guide post 2, the mechanical pencil holder 4 and the ball point pen-holder 5 as well as the sliders 6 and 7 and the other posts are put together, then threaded portion 20 of the guide post 2 is screwed into externally threaded portion 10 of the body 1, and then the lower end side of the cap 3 is rotatably fitted on the upper end of the body 1. At this time the shaft insert hole 35 of the cap 3 is forced onto the engaging shaft portion 25 of the guide post 2 from the top, so that locking claw 25a passes through the shaft insert hole 35 and engages with the upper end surface about the shaft insert hole 35, so retaining the cap 3 in place. A top machine screw 8 is screwed into the internally threaded portion 36 at the top of cap 3, so that thrust shaft portion 8a of the top machine screw 8 is inserted between the forks of engaging shaft portion 25, to make engagement of the locking claw 25a within the shaft insert hole 35 more positive and firm. Also, a securing ring of a clip 9 is fastened to cap 3 by means of the top machine screw 8. Thus, the final assembly of the writing utensil takes place with the sliders 6 and 7 retracted and urged by their own elastic members 46 and 52 so that adjacent lower end surfaces of the cam surfaces 61 and 71 on the sliders 6 and 7 are forcibly engaged with the cam engaging projection 34 on cap 3. In other words, as shown in Figure 13, the lower ends of cam surfaces 61 and 71 become a tapered short-circuit when the sliders 6 and 7 are fitted together at the retracted position. Under the condition shown in Figures 1, 12 and 13 where both lower ends of cam surfaces 61 and 71 engage with cam engaging projection 34, the respective sliders 6 and 7 are retracted so that both the mechanical pencil holder 4 and the ball point pen-holder 5 are maintained at a retracted and contained position in the body 1. On the other hand, when the cam engaging projection 34 is engaged with one or other of the locking portions 61a and 71a at the top of cam surfaces 61 and 71, by the rotation of the cap 3, the engaged slider 6 or 7 is advanced so that the corresponding refill is kept at a writing position, projecting from the body 1. Thus the mechanical pencil holder 4 and the ball point pen-holder 5 are alternately moved forwards and backwards by means of a rotation of the cap 3, while they may be contained together within the body of the utensil. It is to be understood that since sliders 6 and 7 have a rotation restricting function for the cap 3, the rotation-stop projection 33 which is incorporated with cap 3 may be omitted. More specifically, the cap 3, which is held rotatable in place by the engagement of locking claw 25a with the shaft insert hole 35, is rotated so the cam engaging projectiong 34 slides towards the top of either of the cam surfaces 61 and 71 and engages either of locking portions 61a and 71a and either of the sliders 6 and 7 advances so that they are axially offset from one another and a side the other slider 6 or 7, being in a retracted position, is exposed, so cam engaging projection 34 engages with that exposed end surface, thereby restricting rotation. With such an arrangement cap 3 can be rotated by about 180 degrees. Next, the operation of the above described embodiment of the writing utensil will be described. With the mechanical pencil holder 4 and the ball point pen-holder 5 both retracted and contained in the body 1 shown in Figures 1 and 12, when the cap 3 is rotated the cam engaging projection 34 slides urgingly on, for example, the cam surface 61 of the slider 6 on the side of the mechanical pencil holder 4 from the lower end thereof to the top and locking portion 61a, whereby slider 6 is advanced against the elastic member 46. As a result, the mechanical pencil holder 4 being integral with slider 6 and advances to be projected from the body 1, and when the cam engaging projection 34 engages with the locking portion 61a of cam surface 61, the mechanical pencil holder 4 is maintained in a writing position. In this writing position, when the cap 3 is knocked, the slider 6 moves downwardly further through the cam engaging projection 34 engaging with the end locking portion 61a of cam surface 61, whereby a lead of the mechanical pencil holder 4 is fed out. When cap 3 is reversely rotated from this writing position, engagement of cam engaging projection 34 with the locking portion 61a is released, so that the cam engaging projection 34 rotates along the direction where cam engaging projection 34 leaves cam surface 61, whereby slider 6 moves upwards by means of the urging force of the elastic member 46, and, because of this upward movement of the slider, the mechanical pencil holder 4 is retracted and contained in the body 1, and at the contained position, cam engaging projection 34 has allowed cam surface 61 to return to a state where the lower end of cam surface 61 is engaged with the cam engaging projection 34. When cap 3 is rotated in the opposite direction from that initially mentioned above, cam engaging projection 34 slides urgingly on the cam surface 71 of the slider 7 on the side of the ball point pen-holder 5, towards the locking portion 71a, whereby slider 7 moves downward to project the ball point pen-holder 5 to a writing position. Eventually, the cam engaging projection 34 engages with the locking portion 71a of the writing position, whereby the ball point pen-holder 5 is maintained at a locked state. In the state just described, when the cap 3 is reversely rotated, the slider 7 for the ball point pen-holder 5 is retracted into the body of the writing utensil. In the position where the mechanical pencil holder 4 has been projected and the ball point pen-holder 5 has been retracted by means of a rotation of cap 3 in one direction, the cam engaging projection 34 is engaged with a side surface of the slider 7 for ball point holder 5 (or stop 33 engages stop 28), whereby the rotation of cap 3 in that direct ion is restricted. On the other hand, cam engaging projection 34 engages with the side surface of slider 6 (or stop 33 engages the other side surface of stop 28) at a position where the mechanical pencil holder 4 has been retracted and the ball point pen-holder 5 has been projected by a rotation of cap 3 in the other direction, whereby rotation of the cap 3 in the other direction is restricted. Figures 49 to 51 illustrate a modification of the first embodiment shown in Figures 1-14 and common reference numerals designate like or corresponding parts throughout these views. In the modified embodiment an excessive writing pressure moderating mechanism 500 is mounted on the lower part of slider 6 for a mechanical pencil holder 4, as shown in Figures 49 and 50, which functions to prevent breakage, slippage and the like of a lead in such a way that the whole of the mechanical pencil holder 4 is retracted into body 1 when an excessive writing pressure is applied to the lead of the mechanical pencil. The mechanism 500 comprises a peg 510 fitted to the top of lead pipe 4 and movably into a space 62 defined in the lower outside part slider 6, and an elastic member in the form of a spring 412 for moderating excessive writing pressure, disposed in the space 62 between the peg 510 and a wall 62a of space 62, which urges peg 510 and the mechanical pencil holder 4 downwards in a retractable manner. It is to be noted that the elastic member is not limited to a cushion spring, but any elastic member made of sponge, rubber, plastics and the like may be used so far as such member has a prescribed elastic force. While the elastic member 512 which is separate from the slider 6 has been inserted into the space in the above embodiment, such elastic member may be a one-piece molding together with the slider 6. In this case, whole the slider 6 is formed of a synthetic resin such as polyacetal, polypropylene, or the like, and the elastic member 512 which has been subjected to one-piece molding in the space 62 may have any construction of a profile such as branched, strip-like, bent strip-like, or slit-like etc. profile so that such an elastic member has an elastic force which can urge downwardly the peg 510. It is to be understood that a modulus of elasticity of the elastic member 512 is smaller than that elastic member 45. Meanwhile a ball point pen holder 5 is detachably connected to the cover end of pen attaching shaft 50 inserted slidably into either of slide holes 37 through a pen-holder 51 as shown in Figures 49 and 51. In case of the ball point pen-holder 5, breaking of a lead or the like due to an excessive writing pressure action need not be taken into consideration, so that no retraction of the ball point pen-holder 5 is required. Thus, an upper larger diameter portion 51C of the pen-holder 51 is contained immovably in space in the slider 7 as shown in Figure 83. As described above, since the pen-holder 51 is directly inserted in and fixed to the slider 7, the number of parts can be reduced so that the cost for such a writing utensil can be reduced. Opening to the spaces 62 and 72 are defined on the sides of the respective sliders 6 and 7, and it is arranged that peg 510 and the upper larger diameter portion 51C of the pen-holder 51 may be inserted through these openings. According to the above construction, when an excessive writing pressure is applied to a lead of a mechanical pencil during a writing or the like operation, cushioning elastic member 512 having a smaller modulus of elasticity than that of the elastic member 45 is compressed so that whole the mechanical pencil holder 4 is retracted inside the writing utensil, whereby breakage of the mechanical pencil lead or slippage thereof due to opening of a chuck can be prevented. As described above, according to the present embodiment, since refills are urged downwards by means of an elastic member for moderating an excessive writing pressure in a retractable manner, when such an excessive writing pressure is applied to a refill lead, whole the refill is retracted inside the writing utensil. Hence, the present embodiment of the invention provides such an advantage of preventing breakage and slippage of the refill lead. Another embodiment of the present invention will be described hereinbelow. Referring to Figures 15 and 16, a writing utensil comprises reference numeral 201 a lower forward outer cylinder or body 201, an upper outer cylinder or cap 203 connected through a guide post 202 to body 201. The cap 203 is axially slidable, so as to be capable of knocking operation, and is rotatable relative to body 201 and guide post 203. Within the body 201 are two refills, a mechanical pencil holder 204 and ball point pen holder 205, which carry a respective slider 206, 207, and which can slide axially in guide holes 225, 226 in guide post 202. A cam cylinder 208 in cap 203 is arranged to alternately project and retract the two refills. The guide post 202 is detachably connected to the top of the body 201, by means of a hollow externally threaded portion 220, at the lower end of the guide post 202 threadedly engaging with an internally threaded portion 210 at the top of the body 201, and the lower side of a lower circular stepped portion 221 of guide post 202 of larger diameter than threaded portion 220, abutting against the top end of body 201. Although the illustrated engagement of guide post 202 and body 201 in the present embodiment is by screw fit, such engagement may be effected by means of a press fit or the like manner. It is to be noted that the outside diameter of lower circular stepped portion 221 of guide post 202 is smaller than that of the body 201. As shown in Figure 17, guide post 202 is provided with an integral shaft portion 222 extending coaxially from stepped portion 221. The shaft portion 222 is formed into a flat plate of a rectangular profile having a thinner thickness S shown in Figure 34 than a breadth H shown in Figure 33. For this reason the axiallength of the cap 203 as well as a diametrical dimension can be shortened so that the whole writing utensil can be made compact. The guide post 203 also has an upper circular stepped portion 223 which is integrally formed at the top of shaft portion 222, and an integral, forked, engaging shaft portion 224 of a smaller diameter than upper portion 223 surmounts the circular stepped portion 223, coaxially. The engaging shaft portion 224 is provided with locking claws 224a. Also, two slide holes 225 and 226 for receiving refills are formed in lower circular stepped portion 221 between the inside of hollow portion 220 and the upper surface of portion 221, and are symmetrically disposed on opposite sides of shaft portion 222. A locking projection 227 for restricting a rotation and axially knocking movement of cap 203 is integrally formed on the outside surface of, and towards the top of, the lower circular stepped portion 221, as shown in Figures 15, 17 and 19 - 21. A circumferential slide groove 230 for engagingly receiving with the locking projection 227 is formed on the inside surface at the lower end of the cap 203 as shown in Figures 19 and 20, to cooperate in restricting axial movement and rotation of the cap 203. The slide groove 230 is formed into a substantially semicircular arcuate profile so that locking projection 227 can be reversibly rotated by 180 degrees and, in this embodiment, an axial slide groove 230a is formed at one end of the slide groove 230, see Figure 20. The axial slide groove 230a allows for knocking a mechanical pencil holder 204 as will be described hereunder and as shown in Figures 31 and 38, a distance equal to a knocking margin (b) in the upper end of the guide post 202 or another knocking margin (a), which is longer than that of the former margin (b), between the upper end of the slide groove 230a and the top of the locking projection 227. Thus, when the locking projection 227, engages top of slide groove 230a at an advanced position of the cap 203 by a knocking operation, a further downward movement of cap 203 is restricted. It is to be understood that the axial slide groove 230a is formed only at one end of the circumferential slide groove 230 in the present embodiment. This is because there is no need of knocking the ball point pen-holder 205, so that only the mechanical pencil holder 204 need be knocked. However, it may be necessary that both refills are capable of being knocked, e.g. where both the refills are as mechanical pencil holders. In that case two axial slide grooves 230a and 230b may be connected with and formed on opposite ends of the circumferential slide groove 230 as shown in Figure 21. The mechanical pencil holder (first refill) 204 and the ball point pen-holder (second refill) 205 are inserted in the slide holes 225 and 226 of guide post 202, respectively to slide axially as shown in Figure 15. Mechanical pencil holder 204, has a lead guide 241 detachably connected to the lower end of a lead pipe 240 inserted into one slide hole 225, and a lead can be supplied to lead pipe 240 by removing the cap 203, by unscrewing the guide 202 from the body 201, and drawing lead pipe 240 out from the lead guide 241. A lead feeding mechanism 242 is disposed at the lower end of the lead guide 241. Furthermore, the lead feeding mechanism 242 has a lead chuck and a chuck fastening ring (not shown) as well as a first elastic member (spring) 243. The ball point pen-holder 205 is detachably connected to the lower end of a pen attaching shaft 250 slidably inserted into the other slide hole 226, by means of a pen holder 251 as shown in Figure 22. The penholder 251 has three portions: an upper connecting cylindrical portion 251A to which is attached an extension shaft portion 250a at lower end of pen attaching shaft 250, by means of press fit, adhesive bonding or the like manner, a central cylindrical portion 251B of a larger diameter than the upper portion 251a, and into which can be fitted a lead pipe (240) of a mechanical pencil holder (240), and a lower, larger diameter cylindrical portion 251C to which is detachably connected the top of ball point pen-holder 205. With this pendholder 251, if the ball point pen-holder 205 connected to the lower, portion 251C is pulled out, another mechanical pencil holder, which may differ from mechanical pencil holder 204 in a diameter of lead or a type thereof can be connected with the central cylindrical portion 251B, so that refills can be interchanged. To the end of each of the mechanical pencil holder 204 and ball point pen-holder 205, are connected sliders 206 and 207. As shown in Figure 23, the sliders 206 and 207 are generally, symmetrical semi-cylindrical, with an axial slide groove 260, 270 formed on the flat surface. These axial slide grooves 260 and 270 have a width corresponding to breadth H of shaft portion 222, and of guide post 202, and the shaft is sandwiched in these grooves so that the sliders can slide separately in the axial direction, while holding shaft portion 222 between them. Thus, opposite side walls of the axial slide grooves 260 and 270 are formed into hooking leg portions 260a, 260a, and 270a, 270a, respectively, which can slide along the opposite side surfaces of shaft portion 222 in the axial direction, while engaging with the shaft upon rotating thereof. Regarding the sliders 206 and 207, because the bottom of the axial slide grooves are in planar contact with the flat surfaces of the shaft portion 222, and hooking leg portions 260a, 260a and 270a, 270a engage with a side surface of guide post shaft portions 222 under rotational load, the sliders 206 and 207 can smoothly and stably slide without slipping out from shaft portion 222. From the centre of the outside curved surface of each of sliders 206 and 207, extends an integral cam engaging projection 261 and 271, (as shown in Figures 15, 16, 23 and 24). The top of cam engaging projections 261 and 271 are formed into a sharply tapered profile as shown in Figures 16 and 24 or a circular or the like profile (not shown). The mechanical pencil holder 204 and ball point pen-holder 205 are always urged in the retracted direction by means of elastic members (springs) 244 and 252 interposed between the top of the lower circular stepped portion 221 of guide post 202 and the underside of sliders 206 and 207. As a result, the top of cam engaging projections 261 and 271 of the respective sliders 206 and 207, are pressed into contact and engage with a cam surface of the cam cylinder 208 as will be described hereinafter. The cam cylinder 208 has, see Figures 25, 26 and 27, has lower curved and inclined cam surfaces 283, 284, which are symmetrical, and the lower junction of which is a lock portion or notch 285 while at the upper junction of which is a locking portion or flat 286. The upper cylindrical portion 282 of the cam cylinder is internally threaded, and axial grooves are formed on the outer surface of the cam cylinder. A restricted diameter, shaft receiving hole 280 is formed inside the cam cylinder.. The cam cylinder 208 is for alternately projecting and retracting mechanical pencil holder 204 and ball point pen-holder 205 is fitted onto the top side of shaft 222 of the guide post 202, to which are attached the refills as a unit, in a reversibly rotatable manner by means of the engaging shaft portion 224 at top end of shaft portion 222 being received into shaft insert hole 280 from below, and the locking claw 224a engages with the top surface of cam cylinder about shaft receiving hole 280, whereby the cam cylinder 208 can rotate around the engaging shaft portion 224 as its centre. Under the condition where the top surface about shaft receiving hole 280 engages with locking claw 224a as shown in Figure 31, a distance (b) is defined between the upper side of upper, circular stepped portion 223 and the under surface of about shaft receiving hole 280. The distance (b) is a knocking margin for feeding a lead in the mechanical pencil holder 204 and which is equal to or a shorter length than the above-mentioned distance (a). Accordingly, cam cylinder 208 can transferable by the distance (b) in the axial direction thereof, and thereby allowing a knocking operation. Furthermore, cam cylinder 208 is engaged to rotate with the cap 203, by means, integral stops 231 on the inside surface at top of the cap 203, (see Figures 15 and 27) which fit into the engage with the axial groove 281 on the outside surface of the cam cylinder 208 (see Figure 15 and Figures 25 - 27). A threaded portion 290 of a machine screw 209, is screwed into the internally threaded portion 282 of can cylinder 208. An integral thrust shaft portion 293 extend, from the centre portion of top machine screw 209 between the forks of engaging shaft portion 224, so that the locking claws 224a, are more positively and firmly pressed into engagement. The top machine screw 209 also fastens ring portion of a clip 300 to the top of the cap 203. Next, operations of the writing utensil according to the above embodiment will be described hereunder. In an intermediate position where the refills 204 and 205 are retracted into the body 201, the cam engaging projection 261 of the slider 206 and the cam engaging projection 271 of the slider are both pressed into engagement with the curved and inclined cam surface 283, 284, by means of elastic members (springs) 244 and 252. When the cap 203 is rotated in one direction, the incorporated cam cylinder 208 is also rotated and the cam engaging projection 261 of the slider 206 on the mechanical pencil holder 204 moves downwards on the curved and inclined cam surface 283 (Figure 28). In this case, a rotational load of the cam cylinder 208 acts on slider 206, but this load is absorbed because the hooking leg portions 260a, 206a of slider 206 engage with the opposite side surfaces of the shaft portion as shown in Figure 23. Thus, the slider 206 slides smoothly along shaft portion 222, and the mechanical pencil holder 204 moves downwards. Meanwhile, the cam engaging projection 271 of the slider 207 in the ball point pen-holder 205 moves on the other curved and inclined cam surface 284 towards the upper locking portion 286, so that the ball point pen-holder 205 moves upward, urged by the elastic member 252. When the cam engaging projection 261 of the mechanical pencil holder 204 and the cam engaging projection 271 of the ball point pen-holder 205 engage with the lower and upper locking portion 285, 286, respectively, the mechanical pencil holder 204 is maintained at a position, projecting from the lower end of the body 201, while the ball point pen-holder 205 is contained and kept at its retracted position in the body 201. In this condition, when the cap 203 is knocked, the cam cylinder 208 moves downwards with the cap 203 so that the slider 206 on mechanical pencil holder 204 is moved by cam cylinder 208. Hence, the lead pipe 240 is pushed downwards and the lead feeding mechanism 242 operates, thereby sending out a lead. From this situation, when the cap 203 is rotated in the other direction, the cam cylinder 208 also rotates in the other direction, so that the cam engaging projection 261 on the mechanical pencil holder 204 moves upwards alone the curved and inclined cam surface 283 of cam cylinder 208 and the cam engaging projection 271 on the ball point pen-holder 205 sides moves downwards on the other curved and inclined cam surface 284 of cam cylinder 208. As a result, the ball point pen-holder 205 advances to be projected and at that position, the cam engaging projection 271 engages with the lower locking portion 285, so that it is maintained at that position, while the mechanical pencil holder 204 is retracted and contained. Figure 29 illustrates a modification of the sliders 206 and 207, wherein one each of the hooting leg portions 260a and 270a is removed compared to sliders 206 and 207 shown in Figure 23, so that the modified sliders 206 and 207 have one hooking leg portion 260a and 270a each, and which are opposite one another. The hooking leg portions 260a and 270a are disposed on side portions of the sliders 206 and 207 so that the hooking leg portion 260a of slider 206 on the mechanical pencil holder 204, engages with one side surface of the shaft portion 222, by means of the rotational load of the cam cylinder 208 when the cam cylinder 208 is rotated to project the mechanical pencil holder 204 (rotation in the direction indicated by arrow (A) in Figure 29), while the hooking leg portion 270a of the slider 207 on the ball point pen-holder 205 engages with the other side surface of the shaft portion 222 by means of the rotational friction or load of cam cylinder 208, when the cam cylinder 208 is rotated to project the ball point pen-holder 205 (rotation in the direction indicated by arrow (B) in Figure 29). Hence, the hooking leg portions 260a and 270a engage alternately with the side surface of the guide post shaft portion 222 by means of rotational load of the cam cylinder 208 in case of a movement to project the mechanical pencil holder 204 or the ball point pen-holder 204 or the ball point pen-holder 205. Therefore, the sliders 206 and 207 do not slip out from the shaft portion 222 due to the rotational load of cam cylinder 208, so that sliders 206 and 207 can stably and smoothly slide along shaft portion 222. Other examples of mechanisms for restricting a transfer of the cam cylinder are shown in Figures 30 - 32 and Figures 33 - 35, in which the guide post 202 and the cam cylinder 208 are modified. First, a modified construction of the guide post 202 will be described in conjunction with Figures 30 - 32. Upper circular stepped portion 223 of the guide post 202 is formed with a diameter equal to a breadth H of the guide post shaft portion 222, and an integral stopper projection 228 for restricting a rotation of the cam cylinder 208 and a transfer in the axial direction, extends from the outside of the upper circular stepped portion 222. On one hand, a modified construction of the cam cylinder 208 will be described in conjunction with Figures 33 - 36. A circumferential slide slot 287 for restricting a transfer of the cam cylinder 208 and in which engages stopper projection 228, is defined midway along outside surface of cam cylinder 208. The slide slot 287 is semicircular about the long side of cam cylinder 208, and axial slide slot 288 extends upwards from one end of the semicircular slot 287 to allow a knocking operation. In the axial slide slot 288, a distance (c) defined between the top end thereof and the top end of the stopper projection 228 (Figure 36) is formed to be equal to or longer than the distances (a) and (b) shown in Figure 35. Furthermore, for easy assembly of cam cylinder 208 and the guide post 202, a guide slot 289 extends axially downwards from midway along semicircular slide slot 287. The stopper projection 228 of the guide post 202 is fitted into the guide slot 289 from the inside when the guide post 202 is inserted into the shaft receiving hole 280 of cam cylinder 208. More specifically, when the locking clan 224a of the guide post 202 is inserted into and through the shaft receiving hole 280 with the stopper projection 228 engages in the guide slot 289, from the inside, the cam cylinder 208 is rotatably meshed and engaged with the engaging shaft portion 224 of the guide post 202. When the stopper projection 228 abuts against the top wall of the circumferential slide slot 287, and the stopper projection can slide in circumferential slide slot 287 by a rotation of the cam cylinder 208, and cam cylinder 208 can be rotated by 180 degrees. Accordingly, the rotation-stop or locking projection 227 and the circumferential slide groove 230 on the cap 203 (Figure 15, 20) become unnecessary, and may be omitted. Furthermore, with stopper projection 228 at the end of the axial slide slot 288 in the circumferential slide slot 287, the stopper projection 228 can be slid in the axial slide slot 288 to permit a down transfer of cam cylinder 208 at the time of knocking for feeding a lead for the mechanical pencil holder 204. In the present modified embodiment, therefore, when the stopper projection 228 engages with an end of the circumferential slide slot 287 by rotating cam cylinder 208 with the cap 203, in either direction, the rotation of cam cylinder 208 in that direction is restricted. When the cam cylinder is rotated so that the stopper projection 228 is by axial guide slot 288 the mechanical pencil shaft 204 projects from the lower end of the body 201 and the ball point pen-holder 205 is contained in its retracted position in the body. In this condition, when the cap 203 is knocked, the incorporated cam cylinder 208 moves downwardly and stopper projection 228 moves upwards in the axial slide slot 288 of the cam cylinder 208, to allow that downward movement. The lead pipe 240 of the mechanical pencil holder 204 is pushed downwards by means of cam cylinder 208, so that the lead feeding mechanism 242 operates to feed out a lead. When the knocking state of cap 203 is released, the cam cylinder 208 transfers upwards by means of the force of the elastic members 244 and 252, the stopper projection 228 engages with the lower end of the axial slide slot 288 and can slide in the circumferential slide slot 287. When cap 203 is rotated in the other direction from the above desdribed situation, the incorporated cam cylinder 208 also rotates in that other direction, the stopper projection 228 slides in the circumferential slide slot 287 towards other end of the slot, and at the same time the cam engaging projection 261 of the slider 206 on the mechanical pencil holder 204 transfers on the curved and inclined cam surface 283 the lower end locking portion 285 to the upper locking portion 286, while the cam engaging projection 271 of the slider 207 in the ball point pen-holder 205 transfers on the other curved and inclined cam surface 284 in the reverse direction. As a result, the ball point pen-holder 205 is projected, whilst the mechanical pencil holder 204 is retracted to be contained, and the stopper projection 228 eventually engages with the other end of the circumferential slide slot 287, whereby rotation of cam cylinder 208 in the other direction is restricted. Figure 37 illustrates another modified embodiment of a mechanism for restricting a transfer of a cam cylinder in a writing utensil having a first second mechanical pencil holder 204, 205, with different diameter leads 208. Specifically, two axial slide slots 288 and 288a are provided, one at each end of the circumferential slide slot 287 to obtain a knocking margin for feeding a lead at the projected positions of both the first and second mechanical pencil holders 204 and 205. Under the circumstances, when the incorporate cam cylinder 208 with the cap 203 in either direction, the cam engaging projection 261 of the slider 206 on the first mechanical pencil holder 204 transfers on the curved and inclined cam surface 283 towards the lower locking portion 285, and the cam engaging projection 271 belonging to the other mechanical pencil holder 205 system transfers on the other curved and inclined cam surface 284 towards the upper locking portion 286, whereby the first mechanical pencil holder 204 moves downwards, while the second mechanical pencil holder 205 moves upwards, and when the stopper projection 228 engages with the end of circumferential slide slot 287, rotation of cam cylinder 208 in that direction is restricted, so that the first mechanical pencil holder 204 projects from the lower end of the body 201 and at the same time, the second mechanical pencil holder 205 is contained in the body 201 at its retracted position. In this condition, when the cam cylinder 208 is transferred downwards by a knocking operation of the cap 209, a lead is sent out for the first mechanical pencil holder 204. When cam cylinder 208 is rotated in the other, reverse direction, the first mechanical pencil holder 204 retracts, while the second mechanical pencil holder 205 advances to be projected, and the cam cylinder 208 can be transferred downwards by a subsequent knocking operation, whereby a lead is sent out from the second mechanical pencil holder 205. Thus, the first and second mechanical pencil holders 204 and 205 are alternately projected and retracted by means of the reversible rotation of the cam cylinder 208. When, by means of a rotation of cam cylinder 208 in either direction, the stopper projection 228 engages with an end of the circumferential slide slot 287 with either of the first and second mechanical pencil holders 204 and 205 projected whilst the other mechanical pencil holder is retracted, further rotation of the cam cylinder 208 in that direction is restricted. Moreover, a rotation of cam cylinder 208 in the other direction is restricted at a position where either of mechanical pencil holders 204 and 205 is retracted, whilst the other mechanical pencil holder is projected by means of a rotation of the cam cylinder 208 in that direction. Furthermore, when cam cylinder 208 is rotated by about 90 degrees, the cam engaging projections 261 and 271 of the sliders 206 and 207 in the first and second mechanical pencil holders 204 and 205 are maintained in respective intermediate portions of the curved and inclined cam surfaces 283 and 284 on the opposite sides of the cam cylinder 208. As a consequence, mechanical pencil holders 204 and 205 are both maintained in the body 201 at their contained positions, respectively. Figures 38 to 43 illustrate another modified embodiment of a mechanism for restricting a transfer of a cam cylinder wherein rotation of the cam cylinder 208 is restricted by an engagment of an integral stop projection 280a on the inside surface of the cam cylinder 208, with a locking groove 224a defined on the guide post 202. More specifically, the rotation-stop projection 280a extends on the inside surface of the cam cylinder 208 and just below the shaft receiving hole 180. A notched engaging groove 223a with which rotation-stop projection 280a engages to restrict rotation of cam cylinder 208, is defined on the outside of the upper circular stepped portion 223 of the guide post 202 as shown in Figures 39 - 41. The notched engaging groove 223a is substantially semicircular, so that rotation-stop projection 280a can rotate by 180 degrees. To secure the cam cylinder 208 and cap 203A locking projection 208a are formed on the outside, upper end of cam cylinder 208, and fit into and engage with the locking grooves 203a defined on the inside surface of the cap 203. Alternatively, a looking groove may be formed on the outside surface, of the upper end of cam cylinder 208, and a locking projection formed on the inside surface of the cap 203. Figures 44 and 45 illustrate another modified embodiment of a mechanism for restricting a transfer of a cam cylinder wherein rotation of the cam cylinder 208 is restricted by an engagment of rotation-stop projection 280a extending from the inside circumferential surface of the cam cylinder 208 with the cam engaging projections 261 and 271 of the sliders 206 and 207. Accordingly, the engaging groove 223a of the upper circular stepped portion 223 on the guide post 202 is not required in the present embodiment unlike the above modified embodiment. More specifically, in the present modification, a rotation-stop projection 280a is formed on an upper locking portion for locking the cam engaging projections 261 and 271 of the sliders 206 and 207 in case of retracting the refills 204 and 205 as shown in Figure 44. Therefore, the rotation-stop projection 280a engages with the cam engaging projection 261 and 271 to restrict a reversible rotation of the cam cylinder 208, so that excessive rotation of the cam cylinder 208 can be prevented in the present modified embodiment. Also in the present modified embodiment, a knocking margin (b) is allowed between the cam engaging projection 261 and 271 and the upper locking portion 286, whereby either or both of the first and second refills 204 and 205 can be knocked (in this case, the upper locking portion 286 is formed into a shape indicated by a solid line in Figure 44 or 45), or either or booth of them can be held against knocking (in this case, the upper end locking portion 286 is formed into a shape indicated by a dotted line in Figure 44 or 45). Figures 46 - 48 illustrate a modified embodiment of a construction for connecting the body 201 with the guide post 202 wherein a cylindrical portion 222A is disposed on the lower end of the lower circular stepped portion 221 of the guide 202, with outside diameter being equal to the inside diameter of the body 201, and a plurality of integral locking projections 222B and protrude from the outside surface of the cylindrical portion 222A. On the upper end of the body 201 are an axial guide slots 211 each for receiving one of locking projections 222B, from the top and a circumferential locking hole 212 communicating with the lower end of axial guide slot 211 to receive the respective locking projection 222B from the axial guide slot 211 as shown in Figure 63. On the inlet side of each circumferential locking hole 212 is a locking stepped portion 213, and an inclined elastic locking piece 214 inclined on the lower side thereof. Hence, when locking projection 222B is pushed into axial guide hole 211 from the top end and the guide post 202 is rotated, locking projection 222B is pushed into the circumferential locking hole 212 and press fitted into and locked by locking stepped portion 213 by means of elastic force of elastic locking piece 214. As a consequence, the guide post 202 can be detachably connected to the body 201 in one-shot manner. The other construction of the present modified embodiment than those described above is the same with the aforementioned embodiment, so that the same advantages can also be obtained.

Claims: A writing utensil comprising: a tubular body (1); a guide post (2) detachably fitted to one end of the tubular body (1); a hollow cap (3) rotatably secured to the body (1) by means of the guide post (2); first and second axially displaceable sliders (6, 7) received into said cap (3) and prevented from rotation around the longitudinal axis of the utensil by said guide post (2), each of said sliders (6, 7) mounting a refill writing element (4, 5) and cam means arranged to displace said sliders (6, 7) upon relative rotation of the body (1) and the cap (3) in order to selectively project one of said writing elements and retract the other; a shaft engagement portion (25) formed at the rear end of the guide post (2) remote from the body (1), the shaft engagement portion being divided in the diametric direction to provide resiliently deformable locking claws (25a) adapted to engage in a shaft insert hole (35) formed in the cap (3) whereby the cap (3) is secured to the body (1); the shaft insert hole (35) being formed near to an open end of the cap (3), said end being adapted to securely receive a top machine screw (8) characterised in that the top machine screw (8) has a thrust shaft portion (8a) arranged to engage between the locking claws (25a) and thereby prevent the locking claws from disengaging the shaft insert hole (35).

Inventors: EBINUMA, TADAYOSHI, KOTOBUKI &CO. LTD., KAGEYAMA, HIDEHEI, KOTOBUKI & C0. LTD., KUBOTA, MASUO, KOTOBUKI & C0. LTD., Ebinuma, Tadayoshi, Kotobuki &amp;Co. Ltd., Kageyama, Hidehei, Kotobuki &amp; C0. Ltd., Kubota, Masuo, Kotobuki &amp; C0. Ltd.
Applicants: KOTOBUKI & CO., LTD.
Application year: 1987
Main classification: B43K24
IPC codes: B43K24, B43K27