SIDE-KNOCK MECHANICAL PENCIL

Abstract: A side-knock mechanical pencil comprising a lend extending mechanism disposed inside a barrel, and a knock piece so disposed on the side of the barrel as to be pushed diametrically. The lead extending mechanism is moved axially by the pushing action of the knock piece to thereby extend the lead from the barrel. The side-knock mechanical pencil further comprises a lead insertion portion for allowing the lead to pass in the direction where the knock piece is pushed, the lead insertion portion having a diameter at least two times or more the diameter of the lead, and at least one lead receiving portion in front of the lead insertion portion.

Description: Technical Field The present invention relates to a side-knock type mechanical pencil in which a lead feeding mechanism is disposed in an inside portion of a barrel and a knock button is disposed in a side portion of the barrel so that the knock button can be pressed inward in a radial direction of the barrel, and the knock button is pressed to move the lead feeding mechanism back and forth, thereby feeding a lead from the barrel. Background Art Japanese Utility Model Laid-Open No. 55-171577/1980 is known as one example of a side-knock type mechanical pencil. This publication describes a head and a side-knock type mechanical pencil in which an internal tube provided with a mouth ring at its lower end and shorter than an external barrel is movably accommodated in the external barrel; an internal mechanism return spring and appropriate engaging means which play the roles of projecting the mouth ring from the lower end of the external barrel and retracting the mouth ring into the external barrel are provided in the external barrel; an external hole is provided in proximity to a gripping index of the external barrel; an internal hole is provided in the portion of the internal tube which corresponds to the external hole; a lead case, a joint pipe and a three-split chuck are integrally accommodated in the internal tube; a fastener is provided inside the mouth ring and outside the three-split chuck which projects from the internal tube; a slider which causes the three-split chuck to move in the internal tube toward a lead point and is restored by a spring is provided in the internal tube; a side-knock button which can press downward the inclined surface of the upper end of the slider is provided in the external hole; and a knock cover which can press the three-split chuck toward the lead point is provided at the upper end of the lead case. In operation, one lead is separated from the leads stored in the lead case by the upper end of the joint pipe and is then introduced into the three-split chuck through the joint pipe. The slider and the three-split chuck move forward by the radial pressure of the side-knock button, so that the lead gripped by the three-split chuck is fed forward. In general, if the side-knock type mechanical pencil is made to carry out a lead feeding operation, i.e., if the side-knock button is pressed, the forces act on the slider not only in the forward direction thereof but also in the direction in which the side-knock button is pressed. The force which acts on the slider in the latter direction becomes a force which inclines the slider, and this force increases as the side-knock button is pressed. The inclination of the slider bends the connection portion between the joint pipe and the three-split chuck. At this time, a failure occurs in the feeding of the lead, i.e., the lead is caught by the bending so that it becomes unable to be fed in the forward direction or in a sufficient amount. In recent years, consumers have increasingly preferred inexpensive products. It has increasingly necessary to decrease the costs of products because of higher labor costs. Writing tools, such as ball-point pens and mechanical pencils, are not exceptions, and the above-described side-knock type mechanical pencil has been forced to be inexpensively manufactured. To inexpensively manufacture the side-knock type mechanical pencil, there are a number of available methods, such as formation of two parts as one integral part, adoption of a simplified assembling method, or a reduction in the number of parts. However, the formation of two parts as one integral part makes it possible to inexpensively manufacture parts themselves, but may need a complicated and expensive forming mold in order to form a product of particular shape. For this reason, a reduction in the number of parts may be adopted. If the number of parts is reduced, the assembly becomes simple. However, if the number of parts is simply reduced, the required functions will be lost. For example, in the case of the above-described example, if the lead case and the joint pipe are omitted, a lead may exceed the slider and enter a spring portion, so that the lead may not be gripped by the three-split chuck and may become unable to be fed forward. In addition, when the side-knock button is pressed, a lead may be broken. US-A-3883253 discloses a side-knock type mechanical pencil in which a lead feeding mechanism is disposed in an inside portion of a barrel and a knock button is disposed in a side portion of said barrel so that said knock button can be pressed inward in a radial direction. The knock button moves said lead feeding mechanism back and forth, thereby feeding a lead from said barrel. A lead inserting portion for passing therethrough the lead is provided, and said lead inserting portion is formed to have a diameter larger than the diameter of the lead. At least one lead receiving portion is provided forward of said lead inserting portion. JP-Y-52-12489 discloses a similar type of mechanical pencil. Disclosure of Invention According to the present invention there is provided a side-knock type mechanical pencil in which a lead feeding mechanism is disposed in an inside portion of a barrel and a knock button is disposed in a side portion of said barrel so that said knock button can be pressed inward in a radial direction of said barrel, said knock button being pressed to move said lead feeding mechanism back and forth, thereby feeding a lead from said barrel, wherein a lead inserting portion for passing therethrough the lead in a direction that said knock button applies a pressure is provided, and said lead inserting portion is formed to have a diameter at least twice as large as the diameter of the lead and at least one lead receiving portion is provided forward of said lead inserting portion, wherein said knock button is disposed in the side portion of said barrel so that said knock button can be pressed straightforward inward in the radial direction of said barrel, and said knock buttonhas an engagement portion formed in an oblique direction with respect to the direction of movement of said knock button, said lead feeding mechanism has an engagement receiving portion for engaging with said engagement portion, wherein said knock button is U-shaped in cross-section with forward and rearward engagement portions on one side and forward and rearward engagement portions on the other side, said engagement portions each having an inclined surface, wherein the lead feeding mechanism has forward and rearward engagement receiving portions on one side and forward and rearward engagement receiving portions on the other side, said engagement receiving portions each having an inclined surface, and wherein the U-shaped knock button fits over the lead feeding mechanism such that each of said engagement portions slidably engages a respective engagement receiving portion on said lead feeding mechanism. Brief Description of Drawings Fig. 1 is a diagrammatic longitudinal half-sectional view showing a mechanical pencil; Fig. 2 is a diagrammatic perspective view showing the engagement relationship between a knock button and an engagement portion; Fig. 3 is a cross-sectional view taken along line A-A of Fig. 1; Fig. 4 is a diagrammatic perspective view showing part of the barrel shown in Fig. 1; Fig. 5 is a diagrammatic longitudinal half-sectional view showing the pressed state of the knock button; Fig. 6 is a cross-sectional view taken along line B-B of Fig. 5; Fig. 7 is a perspective view showing another example of the knock button; Fig. 8 is a view showing another example of the barrel; Fig. 9 is a perspective view showing a guide member; Fig. 10 is a longitudinal half-sectional view showing a first embodiment of the present invention; Fig. 11 is a diagrammatic perspective view showing the engagement relationship between a knock button and an engagement portion; Fig. 12 is a diagrammatic longitudinal sectional view showing the pressed state of a knock button; Fig. 13 is a perspective view showing another example of the knock button; Fig. 14 is a longitudinal sectional view showing another example of use of the present invention; Fig. 15 is a cross-sectional view taken along line C-C of Fig. 14; Fig. 16 is a cross-sectional view showing a second embodiment of the present invention; Fig. 17 is a cross-sectional view similar to Fig. 16, showing the pressed state of the knock button; Fig. 18 is a cross-sectional view showing a modification of the second embodiment of the present invention; Fig. 19 is a cross-sectional view similar to Fig. 18, showing the pressed state of the knock button; Fig. 20 is a longitudinal sectional view showing a third embodiment of the present invention; Fig. 21 is a diagrammatic perspective view showing the engagement relationship between a knock button and an engagement portion; Fig. 22 is a longitudinal half-sectional view showing a slide member; Fig. 23 is a cross-sectional view taken along line D-D of Fig. 20; Fig. 24 is a cross-sectional view similar to Fig. 23, showing the pressed state of the knock button; Fig. 25 is a longitudinal sectional view showing a modification of the slide member; and Fig. 26 is a longitudinal sectional view showing another modification of the slide member. Best Mode for Carrying Out the Invention Figs. 1 to 6 are explanatory views showing a mechanical pencil. A through-hole 2 is formed in the side portion of a barrel 1, and guide projections 3 are formed in the through-hole 2. A knock button 4 having a U-shaped cross section is fitted through the through-hole 2 in such a manner as to be movable in opposite radial directions perpendicular to the barrel 1. Guide grooves 5 which are slideably engaged with the respective guide projections 3 are formed in the opposite external sides of the knock button 4. The knock button 4 also has inclined faces 6 for moving forward a lead feeding mechanism which will be described later. Inclined faces 7 which are parallel to the respective inclined faces 6 are formed on sides opposite to the inclined faces 6. In addition, engagement claws 9 for preventing the knock button 4 from coming off the barrel 1 are respectively formed at the ends of press surfaces 8 of the knock button 4. A lead tank 11 in which to store leads and which is urged rearward by a resilient member 10 such as a coil spring is disposed in a front portion of the barrel 1. This lead tank 11 is capable of storing at least two leads, and the knock button 4 is positioned in an intermediate portion of the lead tank 11. A chuck 13 on which a chuck ring 12 is fitted is fixed in front of the lead tank 11. The chuck 13 serves to release and grip a lead, and the chuck ring 12 serves to open and close the chuck 13. The above-described arrangement constitutes the lead feeding mechanism. An engagement member 14 is fixed to an intermediate portion of the lead tank 11, and inclined grooves 15 are obliquely formed in the engagement member 14. The knock button 4 is slideably engaged with the inclined grooves 15. Specifically, the inclined faces 6 and 7 of the knock button 4 form engagement portions of the knock button 4, and the inclined grooves 15 of the engagement member 14 serve as engagement receiving portions for the respective engagement portions of the knock button 4. Guide grooves may be formed in the through-hole 2 of the barrel 1, and guide projections to engage with the respective guide grooves may be formed on the opposite external sides of the knock button 4. Each of the guide grooves and the guide projections may have a rectangular shape such as that shown in cross section, or may also have an arcuate shape or a shape composed of a combination of a rectangular shape and an arcuate shape. In other words, it is possible to adopt any shape that can satisfy their engagement relationship and prevent the knock button 4 from shaking in the longitudinal direction of the barrel 1. Reference numeral 18 denotes a point member which is screwed on the front end of the barrel 1, and the point member 18 may be formed integrally with the barrel 1. A lead retaining member 19 for preventing a lead from moving rearward is press-fitted in the point member 18, and a lead protecting pipe 20, such as a stainless pipe, for protecting the lead is press-fitted in the tip of the point member 18. The lead retaining member 19 and the lead protecting pipe 20 may be formed integrally with the point member 18. In operation, if the knock button 4 is pressed radially straightforward, the inclined faces 6 of the knock button 4 press the engagement member 14 in the forward direction while sliding on the inclined grooves 15. By this pressing operation, the lead tank 11 and the chuck 13 move forward (refer to Figs. 5 and 6) and the lead is projected from the lead protecting pipe 20. A modification of the knock button 4 will be described with reference to Fig. 7. Engagement portions 21 to engage with the respective inclined grooves 15 of the engagement member 14 are formed as projecting lines on the opposed internal surfaces of a knock button 22. Of course, the engagement portions 21 are formed in inclined states. In this manner, by forming the engagement portions 21 on the opposed internal surfaces of the knock button 22, it is possible to form long guide projections 23 of the knock button 22 to engage with the guide grooves of the barrel 1 (the through-hole 2), so that the shake of the knock button 22 can be effectively prevented compared to the above-described embodiment. In addition to the arrangement of the above-described embodiment, a reduced-diameter portion 24 may be formed in the inside of the barrel 1 rearwardly of the through-hole 2, and the knock button 22 may be arranged so that a rear end face 26 slides in contact with a face portion 25 formed by the reduced-diameter portion 24, whereby the effect of preventing the shake of the knock button 22 can be improved to a further extent (refer to Fig. 8). As another example in which guide grooves or projections are formed in a barrel, a guide member 27 which has guide grooves or projections as shown in Fig. 9 may be fitted in the barrel 1 as a separate member. As another method of preventing the shake of the knock button more effectively, in addition to the above-described arrangement, an elastic film, such as natural rubber or silicone rubber, may be formed on the surface of the knock button, or a resilient member, such as a coil spring or magnets which repel each other, may be interposed between the knock button and the barrel. Figs. 10 to 12 are explanatory views showing a first embodiment of the invention. The through-hole 2 is formed in the side portion of the barrel 1, and a knock button 28 having a U-shaped cross section is fitted through the through-hole 2 in such a manner as to be movable in opposite radial directions perpendicular to the barrel 1. Cutouts 30 are respectively formed in the intermediate portions of side portions 29 of the knock button 28, and front inclined faces 31 are formed at the front ends of the respective side portions 29 of the knock button 28. The side portions of the knock button 28 each of which is defined by either one of the cutouts 30 and the corresponding one of the front inclined faces 31 constitute first engagement portions 32, respectively. Rear inclined faces 33 are respectively formed on the rear sides of the cutouts 30. The side portions of the knock button 28, each of which is defined by either one of the rear inclined faces 33 and the corresponding one of rear end faces 34 of the knock button 28, constitute second engagement portions 35, respectively. Reference numerals 36 denote engagement claws which are respectively formed at the bottom ends of the opposite external sides of the knock button 28 and serve to prevent the knock button 28 from coming off the barrel 1. A lead tank 37 which stores therein a plurality of leads and which is urged rearward by the resilient member 10 such as a coil spring is disposed in a front portion of the barrel 1. The chuck 13 on which the chuck ring 12 is fitted is fixed in front of the lead tank 37. An engagement member 38 is formed integrally with an intermediate portion of the lead tank 37. The engagement member 38 may be prepared as a separate member. If the engagement member 38 is prepared as a separate member, the engagement member 38 and the lead tank 37 may be fixed to each other, for example, by press fitting, by engagement between projections and recesses, or by bonding. Cutouts 39 are formed in an intermediate portion of the engagement member 38, and the portions forward from the individual cutouts 39 constitute first engagement receiving portions 40 which respectively engage with first engagement portions 32 of the knock button 28. Intermediate inclined faces 41 are respectively formed at the rear ends of the first engagement receiving portions 40, and engage with the corresponding front inclined faces 31 of the first engagement portions 32. The portions rearward from the individual cutouts 39 constitute second engagement receiving portions 42 which respectively engage with second engagement portions 35 of the knock button 28. Rear inclined faces 43 are respectively formed at the rear ends of the second engagement receiving portions 42, and engage with the corresponding intermediate inclined faces 33 of the second engagement portions 35 of the knock button 28. More specifically, the first engagement portions 32 of the knock button 28 are respectively inserted into the cutouts 39 of the engagement member 38, and the second engagement receiving portions 42 of the engagement member 38 are respectively inserted between the first engagement portions 32 and the second engagement portions 35 of the knock button 28. The front inclined faces 31 formed on the first engagement portions 32 of the knock button 28 and the intermediate inclined faces 33 formed on the second engagement portions 35 of the knock button 28 may be curved to reduce sliding resistance, so that the knock button 28 can be pressed more smoothly. Similarly to the modification of Fig. 7, as shown in Fig. 13, first engagement portions 45 and second engagement portions 46 may be formed on the internal surface of a knock button 44, and inclined groove-shaped engagement receiving portions 48 and 49 which respectively engage with the first engagement portions 45 and the second engagement portions 46 may be formed in an engagement member 47. Since the first engagement portions 45 and the second engagement portions 46 of the knock button 44 can be hidden, it is possible to provide a product having a good external appearance. In operation, if the knock button 28 is pressed radially straightforward, the front inclined faces 31 and the intermediate inclined faces 33 of the knock button 28 press the engagement member 38 in the forward direction while sliding on intermediate inclined faces 41 and rear inclined faces 43 of the engagement member 38. By this pressing operation, the lead tank 37 and the chuck 13 move forward (refer to Fig. 12) and a lead is fed forward. An example of the present invention having an added value will be described below with reference to Figs. 14 and 15. In this example, a rod-shaped feeding device capable of varying the amount of projection of an eraser is provided at a rear portion. The rod-shaped feeding device will be described below. The internal side of the rear end portion of the barrel 1 (a rear portion 1a) has a ten-angle shape as shown in Fig. 15 in cross section, but may have a square shape, an elliptical shape or any shape other than a circular shape. A rod-shaped guide member 50, which has a fitting portion 50a of ten-angle cross-sectional shape at its front portion, is fitted in the rear portion 1a, so that the barrel 1 and the rod-shaped guide member 50 are engaged in such a manner as to be nonrotatable with respect to each other. Guide grooves 50b which are opposed to each other are formed in the rear portion of the rod-shaped guide member 50, and the rear ends of the guide grooves 50b are joined together and a flange 50c is formed. An external tube 51 is fitted on the rod-shaped guide member 50, and a helical groove 51a is formed in the internal side surface of the external tube 51. The external tube 51 is clamped between the flange 50c which is engaged with one end of the external tube 51 and a fixing member 52, such as an O-ring, which is engaged with the other end of the external tube 51, and is secured to the rod-shaped guide member 50. Reference numeral 53 denotes a rod-shaped receiving member for clamping an eraser 54b. An engagement projection 53a is formed on the side surface of the rod-shaped receiving member 53, and is engaged with the helical groove 51a via the guide grooves 50b. In operation, if the external tube 51 is relatively rotated with respect to the barrel 1 (the rod-shaped guide member 50 ) , the rod-shaped receiving member 53 moves upward as viewed in Fig. 14 by means of the helical groove 51a. By this movement, the eraser 54b is projected. If the eraser 54b is to be retracted, the external tube 51 may be reversely rotated. If a pressure mechanism for feeding a lead, such as that used in the above-described mechanical pencil of figs 1 to 6, is provided on the lead tank, the rod-shaped feeding device can be added without increasing the overall length of the barrel. If the above-described rod-shaped feeding device is provided in the prior art side-knock type of mechanical pencil, the overall length of the barrel increases so that the operability thereof is impaired. This is because a link element which constitutes the pressure mechanism is provided at the position of a lead chuck which constitutes a chuck mechanism. A second embodiment will be described below with reference to Figs. 16 and 17. In the second embodiment, to prevent the shake of the knock button, an improvement is introduced into the state of the knock button fitted through the through-hole in the first embodiment. In the following description, identical reference numerals are used to denote constituent elements identical to those used in the first embodiment. The knock button 28 is formed to increase in width toward its lower portion (toward the engagement claws 36), as viewed in cross section, so that the lower portion of the knock button 28 is press-fitted through the through-hole 2. This large-width portion constitutes a press-fitting portion 54. In addition, the knock button 28 is formed to decrease in width toward its upper portion, so that the width of the upper portion is smaller than that of the through-hole 2. This small-width portion constitutes a non-press-fitting portion 55. If the knock button 28 is pressed, gaps S are produced between the knock button 28 and the wall surface of the through-hole 2 during the process of pressing the knock button 28. In operation, if the knock button 28 which is press-fitted through the through-hole 2 is pressed radially perpendicularly, as by a finger, the front inclined faces 31 and the intermediate inclined faces 33 of the knock button 28 press the engagement member 38 in the forward direction while sliding on the intermediate inclined faces 41 and the rear inclined faces 43 of the engagement member 38. During the process of this pressing operation, the press-fitting action of the knock button 28 with respect to the through-hole 2 is canceled and the gaps S are formed, and the lead tank 37 and the chuck 13 move forward to feed a lead. A modification of the second embodiment will be described below with reference to Figs. 18 and 19. In this modification, the cutouts 39 of the engagement member 38 are formed to constitute a trapezoidal cross-sectional shape (trapezoidal portion 56) the upper side of which is wider than the lower side, and the U-shaped knock button 28 is formed to constitute a trapezoidal internal shape in cross section (trapezoidal portion 57). As shown in Fig. 18, while the pressing operation is not being performed, the trapezoidal portion 56 of the engagement member 38 pushes open the lower end of the trapezoidal portion 57 of the knock button 28, so that the knock button 28 is press-fitted through the through-hole 2. In operation, if the knock button 28 which is placed in a press-fitted state is pressed, the intermediate portion of the trapezoidal portion 57 moves past the upper portion of the trapezoidal portion 56 of the engagement member 38 and then the upper portion of the trapezoidal portion 57 reaches the upper portion of the trapezoidal portion 56, so that the lower portion of the trapezoidal portion 57 of the knock button 28 is restored in a direction for reducing the width of the lower portion of the trapezoidal portion 57. This restoration operation is also due to the reduced width of the lower portion of the trapezoidal portion 56 of the engagement member 38. By the restoration of the trapezoidal portion 57 of the knock button 28, the press-fitted state of the through-hole 2 is canceled, and the gaps S are produced between the external sides of the knock button 28 and the wall surface of the through-hole 2. The timing of canceling the press-fitted state is selected so that the press-fitted state is canceled before the intermediate portion of the trapezoidal portion 57 of the knock button 28 reaches the upper side of the trapezoidal portion 56 of the engagement member 38. A third embodiment will be described below with reference to Figs. 20 to 24. A gripping portion 58, which is knurled or formed by applying and solidifying a paint of comparatively high softness or a liquid rubber material, is formed on the front gripping portion of the barrel 1 (to be gripped during writing). Otherwise, a tubular rubber grip may be fitted as a separate member. By forming the gripping portion 58 or by fitting the rubber grip, it is possible to ease or lessen fatigue due to writing, pains in fingers or the like. The through-hole 2 is formed in the side portion of the barrel 1 rearwardly of the gripping portion 58, and the knock button 28 having a U-shaped cross section is fitted through the through-hole 2 in such a manner as to be movable in opposite radial directions perpendicular to the barrel 1. The knock button 28 has a construction similar to the knock button used in the first embodiment, and the description thereof is omitted. A cap 60 formed integrally with a clip 59 is removably fitted on the rear portion of the barrel 1. Only the clip 59 may be formed integrally with the barrel 1. A slide member 62 which is urged rearward by a resilient member 61, such as a coil spring, is disposed in the front portion of the barrel 1. The chuck 13 on which the chuck ring 12 is fitted is fixed to the front of the slide member 62. The engagement member 38 is formed integrally with the intermediate portion of the slide member 62, but may be prepared as a separate member. If the engagement member 38 is prepared as a separate member, the slide member 62 and the engagement member 38 may be fixed to each other, for example, by press fitting, by engagement between projections and recesses, or by bonding. The engagement member 38 has a construction approximately similar to that of the engagement member used in the first embodiment, and the description thereof is omitted. A lead introducing hole 63 for inserting therethrough approximately two or three leads is formed in the rear end of the slide member 62, and a lead receiving member 64 having an external diameter approximately equal to the internal diameter of the barrel 1 is press-fitted into the rear end portion of the lead introducing hole 63. The inside of the lead receiving member 64 is shaped like a cone so that a lead can easily fall, and a lead inserting hole 66 for introducing the lead into the lead introducing hole 63 is formed in the lower end of a cone-shaped portion 65. The internal portion of the barrel 1 rearward from the lead receiving member 64 constitutes a lead tank portion 67, and leads fall one by one into the lead introducing hole 63 through the lead inserting hole 66. A hole 68 and a chuck press-fitting hole 69 each having a diameter approximately equal to the diameter (external diameter) of a lead is formed in the front portion of the slide member 62 adjacently to the lead introducing hole 63. The diameter of the hole 66 may be made equal to the internal diameter of the lead introducing hole 63 or the internal diameter of the chuck press fitting hole 69, and the diameter of a hole 70 formed in the rear end of the chuck 13 may be made equal to the diameter of the lead. The feature of the above-described third embodiment will be described below. Since the lead introducing hole is formed to have a diameter greater than the diameter of the lead, a core pin is not easily bent in the case of injection molding or the like. In addition, since even a product having a non-circular cross-sectional shape is not easily bent during molding, a straight lead introducing hole can be formed. Since the knock button 28 is disposed rearward of the gripping portion 58 and forward of the clip 59, it is possible to prevent the knock button 28 from being pressed by accident during writing. In operation, if a plurality of leads are inserted into the lead tank portion 67, one lead is separated from the leads by the lead inserting hole 66 of the cone-shaped portion 65 and introduced into the chuck 13 through the lead introducing hole 63 and the hole 68. Even if the leads are curved to some extent or the slide member 62 is curved to some extent, as by molding, since the lead introducing hole 63 is formed to have a diameter greater than the external diameter of each lead, the lead is smoothly introduced into the chuck 13. At this time, if the knock button 28 is pressed radially straightforward, the front inclined faces 31 and the intermediate inclined faces 33 of the knock button 28 press the engagement member 38 in the forward direction while sliding on the intermediate inclined faces 41 and the rear inclined faces 43 of the engagement member 38. By this pressing operation, the slide member 62 and the chuck 13 move forward and the lead is fed forward. Although not shown, since the length of the chuck from its lead gripping portion to its lead receiving portion is selected to be greater than the length of the lead used, the remaining leads excluding one lead which immediately follows the forward fed lead do not come into contact with the rear end thereof, so that the forward fed lead is smoothly inserted into (or smoothly falls into) the lead gripping portion of the chuck. Since one lead immediately follows the rear end of the forward fed lead, as the forward fed lead is gradually worn out (becomes gradually shorter), the immediately following lead is smoothly moved and fed forward. As shown in Fig. 25, the slide member 62 may be composed of two members. If the slide member is composed of two members, it is preferable that, as shown in Fig. 26, a concave-convex engagement portion 69 is formed, so that the two members can be positioned with respect to each other.

Claims: A side-knock type mechanical pencil in which a lead feeding mechanism (38,47) is disposed in an inside portion of a barrel (1) and a knock button (28,44) is disposed in a side portion (2) of said barrel so that said knock button (28,44) can be pressed inward in a radial direction of said barrel (1), said knock buttonbeing pressed to move said lead feeding mechanism (38,47) back and forth, thereby feeding a lead from said barrel, wherein a lead inserting portion for passing therethrough the lead in a direction that said knock button (28,44) applies a pressure is provided, and said lead inserting portion (63) is formed to have a diameter at least twice as large as the diameter of the lead and at least one lead receiving portion (64) is provided forward of said lead inserting portion, wherein said knock button is disposed in the side portion of said barrel so that said knock button can be pressed straightforward inward in the radial direction of said barrel, and said knock button has an engagement portion (32,35; 45,46) formed in an oblique direction with respect to the direction of movement of said knock button, said lead feeding mechanism has an engagement receiving portion (40,42; 48,49) for engaging with said engagement portion (32,35; 45,46) wherein said knock button (28,44) is U-shaped in cross-section with forward and rearward engagement portions (32,35; 45,46) on one side and forward and rearwards engagement portions (32,35; 45,46) on the other side, said engagement portions each having an inclined surface (31,33), wherein the lead feeding mechanism (38,47) has forward and rearward engagement receiving portions (40,42; 48,49) on one side and forward and rearward engagement receiving portions (40, 42; 48, 49) on the other side, said engagement receiving portions each having an inclined surface (41,43), and wherein the U-shaped knock button (28,44) fits over the lead feeding mechanism (38,47) such that each of said engagement portions slidably engages a respective engagement receiving portion on said lead feeding mechanism. A side-knock type mechanical pencil according to claim 1, wherein a press-fitting portion and a non-press-fitting portion are formed in the said knock button (28,44). A side-knock type mechanical pencil according to claim 1, wherein a gripping portion (58) is formed at a front portion of said barrel, a clip (59) is disposed at a rear portion of said barrel, and said knock button (28,44) is disposed rearward of said gripping portion (58) and forward of said clip (59). A side-knock type mechanical pencil according to claim 1, wherein a lead inserting hole (66) formed in said lead receiving portion (64) has a diameter for permitting therethrough one lead to pass. A side-knock type mechanical pencil according to claim 1, wherein a slide member (62) for transmitting an operation of said knock button (28,44) to said lead feeding mechanism is disposed in said lead feeding mechanism so as to constitute part of said lead feeding mechanism, a lead inserting hole (66) is formed in said slide member (62), and a gap is produced between the external diameter of said slide member (62) and said barrel (1), said gap being made smaller than the external diameter of the lead. A side-knock type mechanical pencil according to claim 5, wherein an inclined surface (65) is formed on an internal surface of said slide member (62), said inclined surface being gradually reduced in diameter toward the center of said slide member (62), and said inclined surface and said leadinserting hole (66) are adjacent to each other. A side-knock type mechanical pencil according to claim 1, wherein said lead receiving portion (64) is formed at a rearward portion of said knock button (28,44), said lead receiving portion (64) having an external diameter approximately equal to the internal diameter of said barrel (1) and a lead inserting hole (66) for passing therethrough the lead is formed in said lead receiving portion (64). A side-knock type mechanical pencil according to claim 1, wherein said lead receiving portion (64) is formed integrally with a rearward portion of said knock button (28,44), said lead receiving portion (64) having an external diameter approximately equal to the internal diameter of said barrel (1), and a slit-shaped lead inserting hole for passing therethrough the lead is formed in said lead receiving portion (64).

Inventors: MARUYAMA SHIGEKI, ONUKI SOUJI, MARUYAMA, SHIGEKI, ONUKI, SOUJI
Applicants: PENTEL KK, PENTEL KABUSHIKI KAISHA
Application year: 1996
Main classification: B43K21
IPC codes: B43K21, B43K24