Notepads

Abstract

To provide a writing instrument capable of fitting a cap precisely into a barrel.SOLUTION: A mechanical pencil 1 including a barrel 6 and a cap 70 in which a positioning projection part 6a is formed at one side and a positioning recessed part 70b is formed at the other side on an outer peripheral surface of the barrel and an inner peripheral surface of the cap; when the barrel 6 is tried to be fitted into the cap 70 in a state where the positioning projection part 6a and the positioning recessed part 70b are not aligned along an axial direction, the mechanical pencil is constituted so that the positioning projection part 6a and the positioning recessed part 70b are fitted by a suction force due to a magnetic force working between the barrel 6 and the cap 70 in cooperation of the positioning projection part 6a with the positioning recessed part 70b while rotating the barrel 6 or the cap 70 around a central axis to fit the barrel 6 and the cap 70.SELECTED DRAWING: Figure 21

Description

[Technical Field]

[0001] The present invention relates to a writing instrument. [Background technology]

[0002] BACKGROUND ART Writing implements equipped with a cap for protecting a writing part are known (for example, Patent Document 1).

[0003] The cap fits onto the barrel to protect the writing part from damage due to physical contact, etc., and to prevent the ink in the writing part from drying out. The barrel and cap generally fit together in a snap-fit ​​manner, with a protrusion on the inner circumferential surface of the cap climbing over a protrusion on the outer circumferential surface of the barrel. The user can tell that the fit has been completed by the tactile and audible signals that the fit has been completed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-139135 Summary of the Invention [Problem to be solved by the invention]

[0005] Depending on the height or shape of the protrusions on the barrel or cap, the force required to fit the cap may be too strong, making it difficult for children or the elderly to fit the cap properly. Furthermore, because the cap must be pressed firmly against the barrel when fitting, there is a risk that the edge of the cap's open end may damage the outer surface of the barrel if the cap is inserted at an angle to the central axis of the barrel. Furthermore, if you want to add identification marks, designs, or distinctive shapes such as symbols, letters, or patterns to the outer surfaces of both the barrel and the cap, you need to properly align the barrel and cap in the rotational direction around the central axis.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a writing instrument in which the cap can be fitted accurately to the barrel. [Means for solving the problem]

[0007] According to one aspect of the present invention, a writing instrument is provided which comprises a barrel and a cap, and on the outer peripheral surface of the barrel and the inner peripheral surface of the cap, a positioning protrusion is formed on one side and a positioning recess is formed on the other side, and when the barrel and the cap are attempted to be fitted together while the positioning protrusion and the positioning recess are not aligned along the axial direction, the magnetic attraction acting between the barrel and the cap causes the positioning protrusion and the positioning recess to cooperate and rotate the barrel or the cap around the central axis, causing the positioning protrusion and the positioning recess to fit together, thereby fitting the barrel and the cap together.

[0008] The positioning protrusion and the positioning recess may have complementary portions. A plurality of the positioning protrusions and the positioning recesses may be provided at equal intervals along the circumferential direction. The barrel may be configured so that the cap can be fitted to the front end of the barrel by magnetic attraction. The barrel may be configured so that the cap can be fitted to the rear end of the barrel by magnetic attraction. [Effects of the Invention]

[0009] According to the aspects of the present invention, a common effect is achieved in that a writing instrument is provided in which the cap can be accurately fitted to the barrel. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a vertical cross-sectional view of a mechanical pencil according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of a mechanical pencil. [Figure 3] FIG. 3 is an enlarged cross-sectional view of the front half of the mechanical pencil. [Figure 4] FIG. 4 is an enlarged cross-sectional view of the rear half of the mechanical pencil. [Figure 5] FIG. 5 is a perspective view illustrating the internal structure of the mechanical pencil. [Figure 6] FIG. 6 is an exploded perspective view of the clutch mechanism. [Figure 7] FIG. 7 is an enlarged cross-sectional view of the rotation drive mechanism. [Figure 8] FIG. 8 is a schematic diagram illustrating the rotational drive of the rotor of the rotational drive mechanism. [Figure 9] FIG. 9 is a schematic diagram illustrating the rotational drive of the rotor, following FIG. [Figure 10] FIG. 10 is a perspective view of the dial cam member. [Figure 11] FIG. 11 is a perspective view of the rail cam member. [Figure 12] FIG. 12 is another perspective view of the rail cam member. [Figure 13] FIG. 13 is a perspective view of the dial cam member and rail cam member combined together. [Figure 14] FIG. 14 is another perspective view of the combined dial cam member and rail cam member. [Figure 15] FIG. 15 is a schematic diagram showing a delivery cam surface. [Figure 16] FIG. 16 is a perspective view of the input clutch cam. [Figure 17] FIG. 17 is a perspective view of the output clutch cam. [Figure 18] FIG. 18 is an enlarged perspective view illustrating the input clutch cam and the output clutch cam. [Figure 19] FIG. 19 is a schematic diagram illustrating the operation of the clutch mechanism that cooperates with the rotary drive mechanism. [Figure 20] FIG. 20 is a vertical cross-sectional view of the lead advancing member. [Figure 21] FIG. 21 is an enlarged cross-sectional view of a mechanical pencil illustrating the extension of the writing lead. [Figure 22] FIG. 22 is an enlarged perspective view of the cap. [Figure 23] FIG. 23 is an enlarged perspective view of the barrel. [Figure 24] FIG. 24 is a perspective view of the holding chuck. [Figure 25] FIG. 25 is a vertical cross-sectional view of the holding chuck. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Corresponding components throughout the drawings are designated by common reference numerals.

[0012] FIG. 1 is a longitudinal cross-sectional view of a mechanical pencil 1 according to an embodiment of the present invention, FIG. 2 is a perspective view of the mechanical pencil 1, FIG. 3 is an enlarged cross-sectional view of the front half of the mechanical pencil 1, FIG. 4 is an enlarged cross-sectional view of the rear half of the mechanical pencil 1, FIG. 5 is a perspective view illustrating the internal structure of the mechanical pencil 1, and FIG. 6 is an exploded perspective view of the clutch mechanism 60.

[0013] Mechanical pencil 1 has a front shaft 2, a rear shaft 3 that screws onto the outer peripheral surface of the rear end of front shaft 2, and a tip member 4 that screws onto the outer peripheral surface of the front end of front shaft 2. Front shaft 2 and rear shaft 3 form a barrel 6. The barrel 6 may also include tip member 4. As will be described later, mechanical pencil 1 is configured so that a writing lead 7 protrudes from the tip of slider 9. In this specification, in the axial direction of mechanical pencil 1, the side with the writing lead 7 is defined as the "front" side, and the side opposite the writing lead 7 is defined as the "rear" side.

[0014] Referring to Figure 3, a slider 9 is disposed inside the front end of the barrel 6 so as to be slidable in the axial direction and rotatable about the axis. The slider 9 is formed in a cylindrical shape with an outer diameter that tapers in stages toward the front. A flange portion 9a is provided on the outer peripheral surface of the rear end of the slider 9. The writing lead 7 is guided by the slider 9 and can protrude from the tip of the slider 9. A holding chuck 10 with a through hole 10a formed in its center is disposed inside the slider 9. The through hole 10a of the holding chuck 10 makes sliding contact with the outer peripheral surface of the writing lead 7 and acts to temporarily hold the writing lead 7.

[0015] A cylindrical dial cam member 50, which is a first cam member formed in a cylindrical shape, and a ring-shaped rail cam member 52, which is a second cam member, are arranged on the outer peripheral surface of the slider 9, aligned in the axial direction. A roughly cylindrical gripping portion 8 is provided on the front end of the tip member 4 and on the outer peripheral surface of the dial cam member 50. The tip of the slider 9 protrudes from the hole at the front end of the dial cam member 50. A ball chuck 11, specifically a fastener 13, that grips the writing lead 7 is fitted onto the inner peripheral surface of the rear end of the slider 9.

[0016] The ball chuck 11 has a cylindrical fastener 13, a chuck main body 14 arranged inside the fastener 13, a cylindrical chuck holder 15, and a plurality of balls 16. The inner peripheral surface of the fastener 13 is formed with a tapered surface that widens toward the front. The chuck main body 14 has a through hole for the writing lead 7 formed along the central axis, and the front end of the chuck main body 14 is divided into multiple parts along the axial direction. The rear end of the chuck main body 14 is held by the chuck holder 15. The chuck main body 14 and the chuck holder 15 are movable in the axial direction relative to the fastener 13. The plurality of balls 16 are arranged between the inner peripheral surface of the fastener 13 and the outer peripheral surface of the chuck main body 14.

[0017] When writing pressure is applied to the lead 7, the chuck body 14, together with the ball 16, abuts against the tapered surface inside the cylindrical fastener 13, so that the lead 7 is gripped by the chuck body 14. This prevents the lead 7 from moving backward. On the other hand, when a force is applied to pull the lead 7 forward, the chuck body 14 is not affected by the fastener 13, so the lead 7 can be pulled forward without resistance. In other words, the ball chuck 11 acts to allow the lead 7 to move forward and prevent it from moving backward.

[0018] A coil spring 17 is arranged to surround the chuck main body 14. The rear end of the coil spring 17 is fitted onto the outer surface of the chuck main body 14, and the front end of the coil spring 17 is supported by a step formed on the inner peripheral surface of the fastener 13. The coil spring 17 urges the chuck main body 14 rearward, allowing the ball chuck 11 to maintain a state in which it is gripping the lead 7. A cam abutment spring 18, which is a coil spring, is arranged to surround the fastener 13. The cam abutment spring 18 urges the slider 9 forward. The front end of a lead case 19 is fitted onto the outer peripheral surface of the rear end of the chuck holding portion 15. The lead case 19 is formed in a cylindrical shape and houses the lead 7 inside.

[0019] An input clutch cam 61 of a clutch mechanism 60, which will be described later, is connected to the ball chuck 11. That is, the input clutch cam 61 is formed in a cylindrical shape, and the outer peripheral surface of the rear end of the fastener 13 of the ball chuck 11 is fitted to the inner peripheral surface of the front end of the input clutch cam 61. The outer peripheral surface of the front end of the relay member 12, which is formed in a cylindrical shape, is fitted to the inner peripheral surface of the rear end of the input clutch cam 61. As will be described later with reference to FIGS. 5 and 6, the clutch mechanism 60 has a protruding abutment 65c that protrudes forward. The abutment 65c is urged forward by the cam abutment spring 18 via the slider 9. Therefore, the slider 9, the ball chuck 11, the relay member 12, the input clutch cam 61, and the abutment 65c can move integrally in the axial direction within the shaft cylinder 6. The rear end of the relay member 12 is connected to a rotation drive mechanism 30, which will be described later.

[0020] Referring to Figure 4, a knock rod 20 serving as a knock portion is provided at the rear end of the barrel 6 so as to be movable back and forth relative to the barrel 6. The knock rod 20 is urged rearward by a coil spring 21. A partition wall 20a equipped with a refill hole for the writing lead 7 is formed near the rear end of the knock rod 20. An eraser 22 is removably attached inside the rear end of the knock rod 20. A knock cover 23 is removably attached to the outer peripheral surface of the rear end of the knock rod 20 to protect the eraser 22 from dirt and the like. The knock rod 20 fits into the outer peripheral surface of the rear end of the lead case 19.

[0021] By performing a knocking operation that presses the knock bar 20 or the knock cover 23 forward, the lead case 19 moves forward. This pushes the chuck body 14 forward via the chuck holding portion 15. Accordingly, the writing lead 7 held by the chuck body 14 also moves forward, acting to feed the writing lead 7 from the slider 9.

[0022] When the pressure exerted by the knock operation is released, the knock rod 20 retracts and returns to its original position due to the biasing force of the coil spring 21. At this time, the chuck body 14 retracts due to the biasing force of the coil spring 17. Meanwhile, the writing lead 7 is held by the retaining chuck 10 disposed within the slider 9, and the action of the ball chuck 11 causes the writing lead 7 to be drawn out of the chuck body 14 without resistance. As a result, the writing lead 7 is advanced from the slider 9, and each time the knock operation is repeated, the writing lead 7 can be advanced by a predetermined amount. If the state in which the knock rod 20 is advanced by the knock operation is maintained, the chuck body 14 protrudes from the fastener 13, and the grip on the writing lead 7 is released. In this state, the writing lead 7 that has been advanced from the slider 9 can be pushed back with a fingertip or the like.

[0023] FIG. 7 is an enlarged cross-sectional view of the rotation drive mechanism 30. The rotation drive mechanism 30 is disposed in the internal space of the rear axle 3. The rotation drive mechanism 30 is connected to the rear end of the relay member 12. Axle spring 31 is disposed between the rear end surface of the front axle 2 and the front end surface of the rotation drive mechanism 30, and the rotation drive mechanism 30 is biased rearward. The rearward movement of the rotation drive mechanism 30 due to the biasing force of the axle spring 31 is restricted when the rear end surface of the rotation drive mechanism 30 abuts against a step provided on the inner surface of the barrel 6. The lead case 19 passes through the interior of the relay member 12 and the rotation drive mechanism 30, and is spaced apart from the rotation drive mechanism 30.

[0024] The rotation drive mechanism 30 has a rotor 40 formed in a cylindrical shape, an upper cam forming member 41 which is a first cam forming member formed in a cylindrical shape, a lower cam forming member 42 which is a second cam forming member formed in a cylindrical shape, a cylinder member 43 formed in a cylindrical shape, a torque canceller 44 which is also formed in a cylindrical shape, and a coil-shaped cushion spring 45. The rotation drive mechanism 30 is a unit formed by integrating these members.

[0025] The outer peripheral surface of the rear end of relay member 12 is fitted onto the inner peripheral surface of the front end of rotor 40. Near the front end of rotor 40, there is a flange-shaped portion with a slightly larger diameter, and a first cam surface 40a is formed on the rear end surface of this portion, and a second cam surface 40b is formed on the front end surface of this portion.

[0026] The upper cam forming member 41 rotatably surrounds the rotor 40 behind the first cam surface 40a of the rotor 40. The lower cam forming member 42 is fitted to the outer peripheral surface of the front end portion of the upper cam forming member 41. A first fixed cam surface 41a, which is a first fixed cam surface, is formed on the front end surface of the upper cam forming member 41 facing the first cam surface 40a of the rotor 40. A second fixed cam surface 42a, which is a second fixed cam surface, is formed on the inner surface of the front end portion of the lower cam forming member 42 facing the second cam surface 40b of the rotor 40.

[0027] A cylindrically shaped cylinder member 43 is fitted onto the outer peripheral surface of the rear end of the upper cam forming member 41. An insertion hole 43a is formed in the rear end of the cylinder member 43, through which the lead case 19 can be inserted. A cylindrically shaped torque canceller 44 that is movable in the axial direction is disposed within the cylinder member 43. A cushion spring 45 is disposed between the inner surface of the front end of the torque canceller 44 and the inner surface of the rear end of the cylinder member 43. The cushion spring 45 biases the rotor 40 forward via the torque canceller 44.

[0028] Here, the relay member 12 transmits the backward and forward movement (cushioning movement) of the writing lead 7 based on the writing action to the rotation drive mechanism 30, i.e., the rotor 40, and also transmits the rotational movement of the rotor 40 in the rotation drive mechanism 30, which is generated by the cushioning movement, to the ball chuck 11, which is holding the writing lead 7. Therefore, the writing lead 7 held in the ball chuck 11 also rotates.

[0029] When not writing with the mechanical pencil 1, that is, when no writing pressure is being applied to the writing lead 7, the rotor 40 is positioned forward by the biasing force of the cushion spring 45 via the torque canceller 44. Therefore, the second cam surface 40b of the rotor 40 abuts against the second fixed cam surface 42a and is brought into meshing state. When writing with the mechanical pencil 1, that is, when writing pressure is being applied to the writing lead 7, the ball chuck 11 moves backward against the biasing force of the cushion spring 45, and the rotor 40 also moves backward accordingly. Therefore, the first cam surface 40a of the rotor 40 abuts against the first fixed cam surface 41a and is brought into meshing state.

[0030] Fig. 8 is a schematic diagram sequentially explaining the rotational driving action of rotor 40 of mechanical pencil 1 of Fig. 1, and Fig. 9 is a schematic diagram subsequent to Fig. 8 that explains the rotational driving action of rotor 40. In Figs. 8 and 9, a first cam surface 40a that is continuously sawtoothed along the circumferential direction is formed in an annular shape on the rear end surface, which is the upper surface of rotor 40, and a second cam surface 40b that is similarly continuously sawtoothed along the circumferential direction is formed in an annular shape on the front end surface, which is the lower surface of rotor 40.

[0031] A first fixed cam surface 41a having a continuous sawtooth shape along the circumferential direction is also formed on the annular end face of the upper cam forming member 41 that faces the first cam surface 40a of the rotor 40, and a second fixed cam surface 42a having a continuous sawtooth shape along the circumferential direction is also formed on the annular end face of the lower cam forming member 42 that faces the second cam surface 40b of the rotor 40. The cam surfaces of the first cam surface 40a and the second cam surface 40b formed on the rotor 40 and the cam surfaces of the first fixed cam surface 41a formed on the upper cam forming member 41 and the second fixed cam surface 42a formed on the lower cam forming member 42 are formed so that the pitches are substantially the same.

[0032] 8(A) shows the relationship between the rotor 40, upper cam forming member 41, and lower cam forming member 42 when no writing pressure is applied to the writing lead 7. In this state, the second cam surface 40b formed on the rotor 40 is engaged with the second fixed cam surface 42a of the lower cam forming member 42 by the biasing force of the cushion spring 45. At this time, the first cam surface 40a of the rotor 40 and the first fixed cam surface 41a of the upper cam forming member 41 are set so as to be shifted by half a phase (half a pitch) with respect to one tooth of the cam in the axial direction.

[0033] 8(B) shows the initial state in which writing pressure is applied to the writing lead 7 for writing with the mechanical pencil 1. In this state, the rotor 40 moves backward by contracting the cushion spring 45 as the ball chuck 11 moves backward. As a result, the rotor 40 moves toward the first fixed cam surface 41a of the upper cam forming member 41.

[0034] Next, Figure 8(C) shows a state in which further writing pressure is applied to the writing lead 7, causing the rotor 40 to abut against the first fixed cam surface 41a of the upper cam forming member 41 and move back. In this state, the first cam surface 40a of the rotor 40 is engaged with the first fixed cam surface 41a of the upper cam forming member 41. As a result, the rotor 40 is subjected to a rotational drive equivalent to half the phase (half the pitch) of one tooth of the first cam surface 40a.

[0035] 8 and 9, a triangle mark added to the center of the rotor 40 is used to indicate the amount of rotational movement of the rotor 40. In the state shown in Fig. 8(C), the second cam surface 40b of the rotor 40 and the second fixed cam surface 42a of the lower cam forming member 42 are set to have a relationship in which they are shifted by half a phase (half a pitch) with respect to one tooth of the cam in the axial direction.

[0036] Next, Figure 9(D) shows the initial state when writing with the mechanical pencil 1 has finished and the writing pressure on the writing lead 7 has been released. In this case, the rotor 40 moves forward due to the biasing force of the cushion spring 45. This causes the rotor 40 to move toward the lower cam forming member 42.

[0037] Next, in FIG. 9(E), the rotor 40 is rotated by the biasing force of the cushion spring 45. The second fixed cam surface 42a of the lower cam forming member 42 In this case, the second cam surface 40b of the rotor 40 is engaged with the second fixed cam surface 42a of the lower cam forming member 42. As a result, the rotor 40 is again subjected to a rotational drive force equivalent to half the phase (half pitch) of one tooth of the second cam surface 40b.

[0038] Therefore, as indicated by the triangle mark drawn in the center of the rotor 40, as the rotor 40 receives writing pressure and reciprocates in the axial direction, i.e., moves back and forth, the rotor 40 is rotationally driven by one tooth (one pitch) of the first cam surface 40a and the second cam surface 40b, and the writing lead 7 held by the ball chuck 11 is similarly rotationally driven. Therefore, with one axial movement of the rotor 40 back and forth due to writing, the rotor 40 undergoes a rotational movement corresponding to one tooth of the cam, and by repeating this, the writing lead 7 is sequentially rotationally driven. This prevents uneven wear of the writing lead 7 as writing progresses, and prevents large changes in the thickness and darkness of the drawn lines.

[0039] In short, the rotation drive mechanism has a first cam forming member and a second cam forming member, a rotor formed in an annular shape with a first cam surface and a second cam surface formed on one end face and the other end face in the axial direction, respectively, and a first fixed cam surface and a second fixed cam surface formed on the first cam forming member and the second cam forming member arranged to face the first cam surface and the second cam surface, respectively, and is configured so that when the ball chuck is retracted by writing pressure, the first cam surface of the rotor abuts and meshes with the first fixed cam surface, and when the writing pressure is released, the second cam surface of the rotor abuts and meshes with the second fixed cam surface, and when the first cam surface of the rotor is meshed with the first fixed cam surface, the second cam surface of the rotor and the second fixed cam surface are set in a phase-shifted relationship with respect to one tooth of the cam in the axial direction, and when the second cam surface of the rotor is meshed with the second fixed cam surface, the first cam surface of the rotor and the first fixed cam surface are set in a phase-shifted relationship with respect to one tooth of the cam in the axial direction.

[0040] The torque canceller 44, which pushes the rotor 40 forward by receiving the biasing force of the cushion spring 45, generates a slip between its front end face and the rear end face of the rotor 40, preventing the rotational motion of the rotor 40 from being transmitted to the cushion spring 45. In other words, the torque canceller 44 prevents the rotational motion of the rotor 40 from being transmitted to the cushion spring 45, thereby preventing the cushion spring 45 from twisting back (torque) which would hinder the rotational movement of the rotor 40.

[0041] As described above, the mechanical pencil 1 has a ball chuck 11 and a rotor 40, and is configured so that the writing lead 7 can be advanced forward by releasing and gripping it through the back and forth movement of the ball chuck 11. The ball chuck 11 is held within the barrel 6 so that it can rotate around the central axis while gripping the writing lead 7, and the writing pressure of the writing lead 7 causes the rotor 40 to rotate through the back and forth movement of the ball chuck 11 via the ball chuck 11, and the rotational movement of the rotor 40 is transmitted to the writing lead 7 via the ball chuck 11.

[0042] The lead advancing mechanism and the advancing amount adjustment mechanism will be described with reference to Figures 10 to 14. The lead advancing mechanism receives the rotational driving force of the rotor 40 of the rotation drive mechanism 30 and acts to advance the writing lead 7 from the slider 9.

[0043] FIG. 10 is a perspective view of the dial cam member 50. The dial cam member 50 is positioned so that the upper side in FIG. 10 is the rear side of the mechanical pencil 1. The dial cam member 50 is a cylindrical member and includes a cam body 50a, a flange portion 50b formed on the outer peripheral surface of the cam body 50a, a fitting protrusion 50c formed on the rear end surface of the flange portion 50b, and a dial cam 51 formed on the rear end surface of the cam body 50a. The dial cam 51 includes a flat first annular cam surface 51a located further forward and perpendicular to the central axis, and a flat second annular cam surface 51b located further rearward and perpendicular to the central axis. Furthermore, both ends of the first annular cam surface 51a and the second annular cam surface 51b are connected by a vertical wall 51c.

[0044] FIG. 11 is a perspective view of the rail cam member 52, and FIG. 12 is another perspective view of the rail cam member 52. The rail cam member 52 is arranged so that the upper side is the rear side of the mechanical pencil 1 in FIGS. 11 and 12. The rail cam member 52 is an annular member. An adjustment recess 52a is formed in the front end surface of the rail cam member 52. A plurality of fitting recesses 52b are formed in the bottom surface of the adjustment recess 52a and are arranged in parallel at equal intervals along the circumferential direction.

[0045] A rail cam 53 is formed on the rear end surface of the rail cam member 52. The rail cam 53 has a flat first annular cam surface 53a located further forward and perpendicular to the central axis, a flat second annular cam surface 53b located further rearward and perpendicular to the central axis, and an inclined surface 53c, which is a sloped annular cam surface that rises in the circumferential direction to connect one ends of the first annular cam surface 53a and the second annular cam surface 53b. The other ends of the first annular cam surface 53a and the second annular cam surface 53b are connected by a vertical wall 53d.

[0046] FIG. 13 is a perspective view of the combined dial cam member 50 and rail cam member 52, and FIG. 14 is another perspective view of the combined dial cam member 50 and rail cam member 52. The dial cam member 50 and rail cam member 52 are arranged so that the upper side in FIGS. 13 and 14 faces the rear side of the mechanical pencil 1. The annular rail cam member 52 is inserted into the rear end of the cam body 50a of the dial cam member 50 and engaged by the flange portion 50b, thereby combining the two. That is, the front end surface of the rail cam member 52 abuts against the rear end surface of the flange portion 50b of the dial cam member 50. At this time, the fitting protrusion 50c provided on the flange portion 50b of the dial cam member 50 fits into one of the fitting recesses 52b in the adjustment recesses 52a of the rail cam member 52. The rail cam member 52 is arranged radially outward of the dial cam member 50.

[0047] When the dial cam member 50 and the rail cam member 52 are combined, the dial cam 51 of the dial cam member 50 is disposed adjacent to the rail cam 53 of the rail cam member 52. As a result, the dial cam 51 and the rail cam 53 cooperate to form a series of, i.e., annular, feed cam surfaces 54 in the circumferential direction.

[0048] As shown in FIG. 3, the dial cam member 50 and the rail cam member 52 are arranged outside the slider 9 in an assembled state. The outer circumferential surfaces of a portion of the dial cam member 50 and the rail cam member 52 are covered by the tip member 4 and the grip portion 8. The grip portion 8 engages with the outer circumferential surface of the dial cam member 50. Therefore, it can rotate together with the dial cam member 50 around the central axis. A coil spring 56 is arranged between the inner surface of the front end portion of the tip member 4 and the flange portion 50b of the dial cam member 50. In addition, the abutment 65c, which is urged forward by the cam abutment spring 18 via the slider 9, maintains a state of abutment against the delivery cam surface 54. The outer circumferential surface of the rail cam member 52 engages with the inner circumferential surface of the tip member 4, restricting rotation of the rail cam member 52 relative to the tip member 4 and, ultimately, the barrel 6.

[0049] The shape of the delivery cam surface 54 can be changed by rotating the dial cam member 50 and the rail cam member 52 relatively around the central axis. Specifically, the user rotates the dial cam member 50 around the central axis by holding the barrel 6 with one hand while rotating the grip portion 8 with the other hand. Because the rail cam member 52 is engaged with the barrel 6, the dial cam member 50 rotates around the central axis relative to the rail cam member 52. The rotation of the dial cam member 50 relative to the rail cam member 52 is performed in stages so that the mating protrusions 50c of the dial cam member 50 move between and fit into the corresponding adjacent mating recesses 52b of the rail cam member 52. Therefore, the rotation of the dial cam member 50 around the central axis relative to the rail cam member 52 is performed in stages within the range of the adjustment recesses 52a of the rail cam member 52, within which the mating protrusions 50c of the dial cam member 50 can move. The relative positions of the dial cam 51 of the dial cam member 50 and the rail cam 53 of the rail cam member 52 change depending on the position of the fitting recess 52b of the rail cam member 52 into which the fitting protrusion 50c of the dial cam member 50 fits, and as a result, the shape of the delivery cam surface 54 can be changed. The dial cam member 50 is urged against the rail cam member 52 by the coil spring 56, and a clicking sensation is produced when the dial cam member 50 rotates stepwise relative to the rail cam member 52.

[0050] Next, the advancement of the writing lead 7 by the advancement cam surface 54 will be described with reference to Figure 15. Figure 15 is a schematic diagram showing the advancement cam surface 54. Figure 15 shows a circumferential development of a cylindrical surface around the central axis including the advancement cam surface 54 to show the positional relationship between the dial cam member 50 and the rail cam member 52. In Figure 15, the upper side is the rear side of the mechanical pencil 1.

[0051] 15, the dial cam member 50 is aligned with the rail cam member 52 so that the vertical wall 51c of the dial cam 51 and the slope 53c of the rail cam 53 are radially overlapping. In FIG. 15, the line (plane) located further rearward of the dial cam 51 and the rail cam 53, i.e., the line (plane) located higher in the figure, constitutes the delivery cam surface 54. That is, the second annular cam surface 51b of the dial cam 51 and the second annular cam surface 53b and slope 53c of the rail cam 53 cooperate to constitute the delivery cam surface 54. Note that the height (height difference) of the step 55 (drop) in the axial direction formed by the second annular cam surface 51b of the dial cam 51 and the slope 53c of the rail cam 53 on the delivery cam surface 54 is referred to as the step height H.

[0052] When the dial cam member 50 and the rail cam member 52 are rotated relatively around the central axis so that the vertical wall 51c of the dial cam 51 is positioned on the side of the first annular cam surface 53a of the rail cam 53, the step height H becomes larger. On the other hand, when the dial cam member 50 and the rail cam member 52 are rotated relatively around the central axis so that the vertical wall 51c of the dial cam 51 is positioned on the opposite side to the first annular cam surface 53a of the rail cam 53, the step height H becomes smaller.

[0053] As will be described later, the rotor 40 of the rotation drive mechanism 30 gradually rotates the abutment 65c based on the cushioning action of the writing lead 7. That is, when viewed from the tip of the slider 9, the abutment 65c rotates clockwise around the central axis. Due to this rotational movement, the abutment 65c, which is biased forward by the cam abutment spring 18, moves in the circumferential direction in cooperation with the delivery cam surface 54. That is, as the abutment 65c moves from right to left in FIG. 15, it gradually rises along the slope 53c of the dial cam 51 that constitutes the delivery cam surface 54.

[0054] When the abutment piece 65c reaches the step 55, it is pressed by the biasing force of the cam abutment spring 18 and falls into the step 55. In other words, the abutment piece 65c moves forward from the second annular cam surface 51b of the dial cam 51 by the step height H of the step 55. At this time, as the abutment piece 65c advances, the slider 9 and further the holding chuck 10 disposed inside the slider 9 also move forward. As a result, the writing lead 7 held by the holding chuck 10 is pulled out of the ball chuck 11 and is relatively fed out by the step height H from the tip of the slider 9. Therefore, the amount of writing lead 7 fed out, i.e., the feeding amount, is equal to the step height H.

[0055] Through the above operation, the lead 7 can be advanced from the slider 9 each time the abutment piece 65c makes one revolution along the advancement cam surface 54. By repeating this operation, the lead 7 is worn down with the writing action, and the lead 7 is advanced sequentially.

[0056] In short, in the lead advancing mechanism, the abutment 65c moves along the advancing cam surface 54 in response to the rotation of the rotor 40, and the forward movement of the slider 9 when the abutment 65c drops into the step 55 on the advancing cam surface 54 causes the lead 7 held in the retaining chuck 10 to be pulled out of the ball chuck 11. By utilizing the step 55 on the advancing cam surface 54, the lead advancing mechanism can convert the rotational driving force of the rotor 40 in the rotation drive mechanism 30 into an advancing operation for the lead 7. Configurations that create height differences on the advancing cam surface 54 are collectively referred to as "drops."

[0057] The mechanical pencil 1 is configured so that the writing lead 7 held in the ball chuck 11 is also rotationally driven by the rotational drive force of the rotor 40 in the rotation drive mechanism 30. This prevents uneven wear of the writing lead 7 as the writing progresses, and as a result, prevents significant changes in the thickness and darkness of the drawn lines. In short, the rotation drive mechanism 30 has a rotor 40, and drives the rotor 40 to rotate in one direction in response to the axial backward movement caused by the writing pressure applied to the writing lead 7 held in the ball chuck 11 and the axial forward movement caused by the release of the writing pressure.

[0058] As described above, in the feed amount adjustment mechanism, the step height H of the step 55 on the feed cam surface 54 can be changed simply by relatively rotating the dial cam member 50 and the rail cam member 52 about the central axis. This makes it possible to more easily and accurately adjust the amount of lead 7 fed by the lead feed mechanism.

[0059] By adjusting the amount of lead 7 extension so that the degree of wear of the lead 7 due to differences in writing pressure and lead hardness used by different users is roughly equal, the amount of lead 7 protruding from the slider 9 can be kept constant even while writing is being performed. As a result, the mechanical pencil 1 allows for long periods of writing with just one knock operation. It is preferable to configure the dial cam 51 or rail cam 53 so that a step 55 with a step height H corresponding to a length exceeding the normally expected degree of wear of the lead 7 is formed. This allows the amount of lead 7 extension to be set to suit the preferences of all users.

[0060] In the above-described embodiment, the dial cam member 50 is a cylindrical member serving as the first cam member, but it may be an annular member. Furthermore, the rail cam member 52 is an annular member serving as the second cam member, but it may be a cylindrical member. The first cam member may be provided with a rail cam 53, and the second cam member may be provided with a dial cam 51. That is, a feeding cam surface may be configured by cooperation between an annular or cylindrical first cam member and an annular or cylindrical second cam member disposed radially outward of the first cam member. Furthermore, the step height of the step may be adjusted by moving the first cam member and the second cam member back and forth relative to each other, i.e., by separating them in the axial direction.

[0061] The rail cam member 52 may be configured integrally with the dial cam member 50, with the dial cam member configuring only a single payout cam surface 54. In this case, the payout amount cannot be adjusted as described above, but the number of parts is reduced, allowing for cost savings. To adjust the payout amount, multiple dial cam members with various step heights H may be prepared. In this case, the user may be able to select and replace the dial cam member that achieves the payout amount that is optimal for them.

[0062] Next, the clutch mechanism 60 will be described with reference to Figures 3, 5, 6, and 16 to 19. The clutch mechanism 60 acts to convert the rotational motion of the rotor 40 in the rotation drive mechanism 30, which serves as an input, into the rotational motion of the abutment element 65c, which serves as an output. The clutch mechanism 60 has an input clutch cam 61, which serves as an input member, an output clutch cam 62, which serves as an output member, a transmission cam 64, and a feed cam 65. The mechanical pencil 1 also has a clutch cam holder 66.

[0063] Figure 16 is a perspective view of the input clutch cam 61, Figure 17 is a perspective view of the output clutch cam 62, and Figure 18 is an enlarged perspective view explaining the input clutch cam 61 and the output clutch cam 62. The input clutch cam 61 is arranged so that the upper side is the rear side of the mechanical pencil 1 in Figure 16, and the output clutch cam 62 is arranged so that the upper side is the rear side of the mechanical pencil 1 in Figure 17. In Figure 18, the upper side is the rear side of the mechanical pencil 1.

[0064] The input clutch cam 61 is a cylindrical member, and one cam protrusion 61a is provided on an annular rear end face 61b that constitutes the input cam surface. A flange portion 61c is provided on the outer peripheral surface of the rear end of the input clutch cam 61.

[0065] The output clutch cam 62 is disposed behind the input clutch cam 61. The output clutch cam 62 is a cylindrical member, and a flange portion 62a is provided on the outer peripheral surface of the output clutch cam 62 near its front end. A clutch cam surface 63, which is an output cam surface, is provided on the annular front end surface of the output clutch cam 62. The clutch cam surface 63 is disposed opposite the cam protrusion 61a of the input clutch cam 61. The clutch cam surface 63 is made up of a plurality of peaks 63a and a plurality of valleys 63b with flat bottom surfaces provided between adjacent peaks 63a.

[0066] 18, the cam protrusion 61a of the input clutch cam 61 and the peak portion 63a of the output clutch cam 62 have substantially the same shape. The cam protrusion 61a of the input clutch cam 61 has a first engagement surface 61aa that is substantially perpendicular to the rear end surface 61b and a first inclined surface 61ab that is inclined. Similarly, the peak portion 63a of the output clutch cam 62 has a second engagement surface 63aa that is substantially perpendicular to the bottom surface of the valley portion 63b and a second inclined surface 63ab that is inclined. As will be described later, in operation of the clutch mechanism 60, the first engagement surface 61aa of the input clutch cam 61 engages with the second engagement surface 63aa of the output clutch cam 62, causing the input clutch cam 61 and the output clutch cam 62 to cooperate.

[0067] 3, 5, and 6, the rear end of the transmission cam 64 is fitted onto the outer peripheral surface of the front end of the output clutch cam 62. The transmission cam 64 is inserted until the rear end surface of the transmission cam 64 abuts against the flange portion 62a of the output clutch cam 62. The transmission cam 64 is formed in a cylindrical shape, and first engagement protrusions 64a extending forward and arranged at equal intervals along the circumferential direction are provided on the front end surface. First engagement walls 64b extending along the axial direction are provided on the circumferential side surfaces of the first engagement protrusions 64a. An annular protrusion 64c is provided on the inner peripheral surface of the transmission cam 64.

[0068] The input clutch cam 61 is disposed within the transmission cam 64 so that the flange portion 61c is disposed between the clutch cam surface 63 of the output clutch cam 62 and the annular projection 64c of the transmission cam 64. In other words, the forward movement of the input clutch cam 61 is regulated by the flange portion 61c engaging with the annular projection 64c of the transmission cam 64. The backward movement of the input clutch cam 61 is regulated by the cooperation of the cam projection 61a and the clutch cam surface 63 of the output clutch cam 62.

[0069] A delivery cam 65 is disposed in front of the transmission cam 64. The delivery cam 65 is formed in a cylindrical shape, and its rear end surface is provided with second engagement protrusions 65a that extend rearward and are equally spaced along the circumferential direction. The second engagement protrusions 65a have a shape complementary to the first engagement protrusions 64a of the transmission cam 64. A second engagement wall 65b is provided along the axial direction on the circumferential side surface of the second engagement protrusion 65a. The front end surface of the delivery cam 65 is provided with the above-mentioned one protruding abutment 65c that protrudes forward. An annular protrusion 65d is provided on the inner circumferential surface of the front end of the delivery cam 65.

[0070] The slider 9 is inserted into the payout cam 65 from the rear, and the flange portion 9a can be engaged with the annular protrusion 65d of the payout cam 65. The above-mentioned cam contact spring 18 is arranged so that one end engages with the inner surface of the flange portion 9a of the slider 9 and the other end engages with the front end surface of the input clutch cam 61. The slider 9 is urged forward by the biasing force of the cam contact spring 18, and the payout cam 65 is urged forward via the biased flange portion 9a of the slider 9. As a result, the abutment 65c is urged so as to abut against the payout cam surface 54, as described above. The payout cam 65 can move integrally with the slider 9 in the axial direction but can rotate independently about the central axis.

[0071] The clutch cam holder 66 is cylindrical and attached to the barrel 6, specifically, the inner surface of the front barrel 2. A liquid lubricant such as grease is applied to the inner surface of the clutch cam holder 66 as a high-viscosity material. The output clutch cam 62 is inserted into the clutch cam holder 66, filling the gap between the outer surface of the output clutch cam 62 and the inner surface of the clutch cam holder 66 with liquid lubricant. As a result, the output clutch cam 62 and the connected transmission cam 64 are loosely held by the clutch cam holder 66, reducing sudden axial movement within the barrel 6 due to gravity and other factors. The clutch cam holder 66 may be integral with the barrel 6. That is, a viscous fluid that suppresses axial movement of the output member is disposed between the output member and the barrel. The inclusion of the clutch cam holder 66 in the mechanical pencil 1 can absorb dimensional variations and frictional resistance among the components of the clutch mechanism 60. The clutch cam holder 66 may also be omitted.

[0072] 3, as described above, the outer peripheral surface of the rear end of the fastener 13 of the ball chuck 11 is fitted to the inner peripheral surface of the front end of the input clutch cam 61, and the outer peripheral surface of the front end of the relay member 12 is fitted to the inner peripheral surface of the rear end of the input clutch cam 61. The rear end of the relay member 12 is connected to the rotor 40 (FIG. 4). Therefore, the input clutch cam 61 is rotated by the rotor 40 via the relay member 12 by the rotation drive mechanism 30. Furthermore, the input clutch cam 61 moves back and forth together with the rotor 40 via the relay member 12 based on the cushioning action of the writing lead 7. The relay member 12 penetrates the insides of the output clutch cam 62 and the transmission cam 64 and is separated from the relay member 12. Therefore, the rotational movement and forward and backward movement of the relay member 12 are not directly transmitted to the output clutch cam 62 and the transmission cam 64.

[0073] As will be described later with reference to Figure 19, the rotational motion of the input clutch cam 61 is transmitted to the output clutch cam 62 by cooperation between the cam protrusion 61a and the clutch cam surface 63 of the output clutch cam 62. The rotational motion of the output clutch cam 62 is transmitted to the delivery cam 65 via the connected transmission cam 64. That is, as the transmission cam 64 rotates, the first engagement wall 64b of the first engagement protrusion 64a engages with the second engagement wall 65b of the second engagement protrusion 65a in the circumferential direction, transmitting the rotational motion of the transmission cam 64 to the delivery cam 65. As a result, the abutment 65c moves along the delivery cam surface 54, as described above, and the writing lead 7 is delivered.

[0074] FIG. 19 is a schematic diagram illustrating the operation of the clutch mechanism 60 in cooperation with the rotation drive mechanism 30. FIG. 19 shows the positional relationship between the rotor 40, upper cam forming member 41, and lower cam forming member 42 in the rotation drive mechanism 30 and the input clutch cam 61 and output clutch cam 62 in the clutch mechanism 60, with a cylindrical surface around the central axis including each cam surface expanded in the circumferential direction. In FIG. 19, the rear side of the mechanical pencil 1 is at the top. The states of the rotation drive mechanism 30 shown in FIGS. 19(A) to 19(E) correspond to the states of the rotation drive mechanism 30 shown in FIGS. 8(A) to 8(C) and 9(D) and 9(E), respectively. Triangle marks are attached to the rotor 40 and the output clutch cam 62 to indicate the amount of rotational movement.

[0075] Figure 19(A) shows the relationship between the rotation drive mechanism 30 and the clutch mechanism 60 when no writing pressure is applied to the writing lead 7. The rotation drive mechanism 30 corresponds to the state shown in Figure 8(A). Therefore, the second cam surface 40b of the rotor 40 is engaged with the second fixed cam surface 42a of the lower cam forming member 42. At this time, the cam protrusion 61a of the input clutch cam 61 and the clutch cam surface 63 of the output clutch cam 62 are separated in the axial direction and do not abut on each other. The triangular marks on the rotor 40 and the output clutch cam 62 are aligned on the same line in the axial direction.

[0076] Next, Figure 19(B) shows the initial state when writing pressure is applied to the writing lead 7. The rotation drive mechanism 30 corresponds to the state shown in Figure 8(B). Therefore, in this state, the rotor 40 moves toward the upper cam forming member 41, and the input clutch cam 61 approaches the clutch cam surface 63 of the output clutch cam 62. At this time, the first engagement surface 61aa of the cam protrusion 61a of the input clutch cam 61 and the second engagement surface 63aa of the peak portion 63a of the output clutch cam 62 (Figure 18) are separated in the circumferential direction, specifically, by a distance D1.

[0077] Next, FIG. 19(C) shows a state in which further writing pressure is applied to the writing lead 7, causing the first cam surface 40a of the rotor 40 to mesh with the first fixed cam surface 41a of the upper cam forming member 41. The rotation drive mechanism 30 corresponds to the state shown in FIG. 8(C). Therefore, the rotor 40 is rotationally driven by a distance equivalent to half the phase (half pitch) of one tooth of the first cam surface 40a. In other words, the rotor 40 rotates from the state shown in FIG. 19(A) by a rotation angle equivalent to the distance L1 of the rotational movement in the circumferential direction. As the rotor 40 is rotationally driven, the cam protrusion 61a of the input clutch cam 61 engages with the peak portion 63a of the output clutch cam 62, and the output clutch cam 62 is rotationally driven via the input clutch cam 61. 19(B), immediately before this, the cam protrusion 61a of the input clutch cam 61 and the peak portion 63a of the output clutch cam 62 are spaced apart in the circumferential direction, and therefore the amount of rotational movement of the output clutch cam 62 is smaller than the distance L1 of the input clutch cam 61, i.e., the amount of rotational movement of the rotor 40. Specifically, the amount of rotational movement of the output clutch cam 62 is distance L2 obtained by subtracting distance D1 from distance L1, and therefore the output clutch cam 62 rotates by a second rotation angle equivalent to distance L2.

[0078] Next, Figure 19(D) shows the initial state in which the writing pressure on the writing lead 7 is released. The rotation drive mechanism 30 corresponds to the state shown in Figure 9(D). Therefore, in this state, the rotor 40 moves toward the lower cam forming member 42 due to the biasing force of the cushion spring 45, and the cam protrusion 61a of the input clutch cam 61 moves away from the clutch cam surface 63 of the output clutch cam 62.

[0079] Next, FIG. 19(E) shows a state in which the second cam surface 40b of the rotor 40 is engaged with the second fixed cam surface 42a of the lower cam forming member 42 due to the biasing force of the cushion spring 45. The rotation drive mechanism 30 corresponds to the state shown in FIG. 9(E). Therefore, the rotor 40 is again subjected to a rotational drive corresponding to half a phase (half a pitch) of one tooth of the second cam surface 40b. That is, the rotor 40, and further the input clutch cam 61 connected to the rotor 40, rotates from the state shown in FIG. 19(A) by a first rotation angle corresponding to a rotational movement distance L3 corresponding to one phase (one pitch). On the other hand, because the cam protrusion 61a of the input clutch cam 61 and the peak portion 63a of the output clutch cam 62 are spaced apart in the axial direction, the first engagement surface 61aa of the input clutch cam 61 and the second engagement surface 63aa of the output clutch cam 62 do not engage with each other, and therefore the output clutch cam 62 is not rotationally driven. The input clutch cam 61 and the output clutch cam 62 are configured to cooperate only at the first engagement surface 61aa of the input clutch cam 61 and the second engagement surface 63aa of the output clutch cam 62, and do not cooperate in other areas.

[0080] When the rotor 40 moves back and forth in the axial direction due to writing, the rotor 40 and the input clutch cam 61 undergo a rotational movement corresponding to one tooth of the cam of the rotational drive mechanism 30, but the output clutch cam 62 undergoes a smaller rotational movement. In other words, the clutch mechanism 60 is configured to transmit the rotational motion of the input clutch cam 61 to the output clutch cam 62 so that when the input clutch cam 61 rotates by a first rotational angle, the output clutch cam 62 rotates by a second rotational angle that is smaller than the first rotational angle. The cam pitch in the clutch mechanism 60 is set smaller than the cam pitch in the rotational drive mechanism 30. Specifically, the output clutch cam 62 is rotationally driven by an angle (second rotational angle) that is the difference between the rotational angle (first rotational angle) corresponding to one tooth of the cam of the rotational drive mechanism 30 and the rotational angle corresponding to one tooth of the cam of the clutch mechanism 60.

[0081] For example, suppose the number of teeth A of the first cam surface 40a of the rotor 40 and the number of teeth B of the clutch cam surface 63 of the output clutch cam 62 are 40 and 46, respectively. The number of strokes, or the number of strokes required for the rotor 40 to rotate one revolution, is 40. The rotation angle C of the rotor 40 per stroke is 360 / A, which is 360 / 40 = 9 degrees. The rotation angle D, which corresponds to the distance between adjacent peaks 63a of the output clutch cam 62, is 360 / D, which is 360 / 46 = 7.83 degrees. Then, as explained with reference to FIG. 19 , the rotation angle E of the output clutch cam 62 per stroke is CD, which is 9 - 7.83 = 1.17 degrees. Therefore, the number of strokes required for the output clutch cam 62 to rotate one revolution is 360 / 1.17 = 307.7 strokes, or 308 strokes. Expressed as a reduction ratio, this is 1 / (C / E) = 1 / 7.69.

[0082] With the clutch mechanism 60, the number of strokes required for the output clutch cam 62, and therefore the abutting element 65c of the payout cam 65, to make one full rotation can be made larger (for example, 308 strokes) than the number of strokes required for the rotor 40 to make one full rotation (for example, 40 strokes). Also, by adjusting the number of teeth A of the cam of the rotation drive mechanism 30 and / or the number of teeth B of the cam of the clutch mechanism 60, the rotor 40 can be made to make one full rotation with any number of strokes, and the writing lead can be paid out with any number of strokes.

[0083] The output clutch cam 62 and the transmission cam 64 may be formed integrally. The output clutch cam 62, the transmission cam 64, and the delivery cam 65 may be collectively formed as an output member. The slider 9 and the delivery cam 65 may be formed integrally. The input clutch cam 61 has one cam protrusion 61a as an input cam surface, but may have multiple cam protrusions 61a. The input cam surface of the input clutch cam 61 and the clutch cam surface 63, which is the output cam surface of the output clutch cam 62, may be formed arbitrarily, as long as they engage during circumferential movement but do not engage during axial movement, as with the relationship between the first engagement surface 61aa and the second engagement surface 63aa. Similarly, the transmission cam 64 and the delivery cam 65 may be formed arbitrarily, as long as they engage during circumferential movement but do not engage during axial movement, as with the relationship between the first engagement wall 64b and the second engagement wall 65b.

[0084] In the above-described embodiment, the input member and the output member are respectively made up of dog clutches, that is, input clutch cam 61 and output clutch cam 62. That is, clutch mechanism 60 is configured such that an input cam surface is formed on the input member and an output cam surface facing the input cam surface is formed on the output member, and the input cam surface and output cam surface engage with each other only during part of the rotational motion of the rotor, so that the rotational motion of the rotor is transmitted to the output member via the input member.

[0085] However, a friction clutch may also be used as the clutch mechanism. That is, the input and output members may be disk-shaped or conical, and the frictional force may be such that when the input member rotates a first rotation angle, the output member rotates a second rotation angle smaller than the first rotation angle. The angle of rotation transmitted from the input member to the output member may be adjusted by changing the shape, material, surface roughness, etc., of the contact surface between the opposing disks or cones of the input and output members. This allows the rotor 40 to rotate once and the writing lead to be advanced at any number of strokes. The contact surface between the input and output members may be made of, for example, rubber or sandpaper. Any clutch mechanism other than a dog clutch or friction clutch may also be used.

[0086] In the above-described embodiment, the ball chuck 11 and the input clutch cam 61 were connected, and the ball chuck 11 was configured to rotate upon receiving the rotational driving force of the rotor 40 via the relay member 12 and the input clutch cam 61, thereby rotating the writing lead 7. However, the ball chuck 11 and the input clutch cam 61 do not have to be connected. In short, the clutch mechanism may be applied to a mechanical pencil in which the writing lead is not configured to rotate.

[0087] After the writing lead 7 is pulled out of the ball chuck 11 by a knocking operation or by the operation of the lead advancing mechanism, but before writing pressure is applied to the writing lead 7, there is structurally room for the writing lead to further retract (backlash). Therefore, if the actual amount of advancing of the writing lead 7 is small, the advancing writing lead 7 may retract due to the backlash, and the writing lead 7 may not actually be advanced.

[0088] The clutch mechanism can delay the timing or frequency of the lead 7 being advanced by the lead advancement mechanism. Therefore, the clutch mechanism allows the lead 7 to be advanced more frequently after the lead 7 has worn down, preventing the lead 7 from essentially not being advanced due to the effects of backlash. The amount of lead advanced can be changed by adjusting the step height H of the lead advancement mechanism, as described above. Therefore, the above-described embodiment can provide a mechanical pencil equipped with a lead advancement mechanism that can more reliably advance the lead.

[0089] As shown in FIG. 1, the mechanical pencil 1 further includes a cap 70 that is equipped with a clip 70a and fits into the barrel 6. The cap 70 includes a cover cap 71, a lead advancing member 72 that serves as a lead advancing portion, and a cushion spring 73. In this specification, the closed end side of the cap 70 in the axial direction is defined as the "front" side, and the open end side is defined as the "rear" side. A lead advancing mechanism that utilizes the lead advancing portion of the cap 70 will be described with reference to FIGS. 20 and 21.

[0090] As shown in Figures 1 and 21(B), the cover cap 71 is a cap-shaped member with a closed front end. The cover cap 71 is attached to the front end of the cap 70, thereby forming the closed end of the cap 70. The lead advancing member 72 is arranged inside the front end of the cap 70 so that it can move back and forth. A cushion spring 73 is arranged between the cover cap 71 and the lead advancing member 72, and the cushion spring 73 urges the lead advancing member 72 rearward.

[0091] Figure 20 is a longitudinal cross-sectional view of the lead advancing member 72. The lead advancing member 72 is a cylindrical member. In Figure 20, the left side is positioned so that the front side of the cap 70 is the left. The rear end surface of the lead advancing member 72 is provided with an insertion hole 72a, which is a circular opening into which the tip of the mechanical pencil 1, i.e., the slider 9, etc., is inserted. The bottom surface of the insertion hole 72a is provided with a storage recess 72b, which has a cylindrical inner surface with an inner diameter R narrower than the entrance of the insertion hole 72a and a depth D2. A tapered surface 72c is provided behind the storage recess 72b. The inner diameter R of the storage recess 72b is set according to the outer diameter of the writing lead 7 used in the mechanical pencil 1. Specifically, the inner diameter R of the storage recess 72b is set slightly larger than the outer diameter of the writing lead 7 so that the tip of the writing lead 7 can be accommodated.

[0092] Figure 21 is an enlarged cross-sectional view of the mechanical pencil 1 illustrating the extension of the writing lead 7. Figure 21(A) shows the state of the mechanical pencil 1 before the writing lead 7 is extended and the cap 70 is not fitted to the barrel 6, Figure 21(B) shows the state of the mechanical pencil 1 with the cap 70 fitted to the barrel 6, and Figure 21(C) shows the state of the mechanical pencil 1 after the writing lead 7 has been extended following the removal of the cap 70 from the barrel 6.

[0093] In Figure 21(A), the writing lead 7 does not protrude from the slider 9. In other words, after the user has completed a series of writing actions, the writing lead 7 is shown to have been retracted so that it does not protrude from the slider 9 in order to protect the writing lead 7.

[0094] Next, as shown in FIG. 21(B), the cap 70 is fitted onto the barrel 6. At this time, the tip of the mechanical pencil 1, i.e., the tip of the lead 7 and the tip of the slider 9, are inserted into the insertion hole 72a of the lead advancing member 72. As described above, the inner diameter R of the accommodating recess 72b is set according to the outer diameter of the lead 7, so that the accommodating recess 72b receives the tip of the lead 7. On the other hand, the outer diameter of the tip of the slider 9 is set larger than the inner diameter R of the accommodating recess 72b. Therefore, as the tip of the slider 9 is inserted into the cap 70, it engages with the tapered surface 72c without being accommodated in the accommodating recess 72b. As a result, the slider 9 retreats relative to the lead 7 within the barrel 6, and as a result, the lead 7 protrudes from the tip of the slider 9 within the cap 70 by a distance equal to the depth D2 of the accommodating recess 72b.

[0095] Next, as shown in Figure 21(C), the cap 70 is removed from the barrel 6 to begin the next writing operation. At this time, the slider 9, which had been retracted, and the holding chuck 10 arranged inside the slider 9 are moved forward by the biasing force of the cam abutment spring 18. As a result, the writing lead 7 held by the holding chuck 10 is pulled out of the ball chuck 11 and relatively extended from the tip of the slider 9 by the depth D2 of the storage recess 72b. Therefore, the amount of writing lead 7 extended, i.e., the extension amount, is equal to the depth D2 of the storage recess 72b.

[0096] Generally, after a user finishes a series of writing actions, they retract the writing lead so that it does not protrude from the tip member or slider to protect it. Therefore, before starting the next writing action, they must perform at least one knocking operation to advance the writing lead in advance. Even in mechanical pencils equipped with the above-mentioned lead advancement mechanism, a writing action is required to automatically advance the writing lead, so they must perform at least one knocking operation to advance the writing lead in advance before starting a writing action.

[0097] With the lead advancing member 72, the writing lead 7 is advanced simply by attaching and detaching the cap 70 to the barrel 6. In other words, the writing lead can be advanced without performing a knocking operation before starting a writing action. Therefore, it is possible to provide a mechanical pencil that allows for a new lead advancing operation that differs from conventional knocking operations.

[0098] Furthermore, even if the cap 70 is fitted to the barrel 6 with the writing lead 7 protruding from the slider 9 longer than the depth D2 of the storage recess 72b, the amount of protrusion of the writing lead 7 does not change. That is, in this state, the tip of the slider 9 does not engage with the tapered surface 72c, and therefore the slider 9 does not recede within the barrel 6 relative to the writing lead 7. At this time, the lead advancing member 72 is pressed by the tip of the writing lead 7 that protrudes further, but this pressure is absorbed by the lead advancing member 72 moving forward against the biasing force of the cushion spring 73.

[0099] The lead advancing member 72 may be replaceable by removing the cover cap 71. In other words, the amount of protrusion of the writing lead 7 varies depending on the user's preference. For example, some users find it convenient to have the writing lead 7 protrude sufficiently, as it allows for longer writing, while others prefer a writing lead 7 that protrudes less because they do not need to worry about the writing lead 7 breaking. Therefore, lead advancing members 72 with storage recesses 72b of various depths D2 may be prepared in advance and made replaceable according to user preference. The cushion spring 73 may be omitted, and the lead advancing member 72 may be fixedly positioned inside the front end of the cap 70.

[0100] The lead advancing portion, which is the lead advancing member 72, may be configured in any way as long as it can press the slider 9 and cause the slider 9 to retract relative to the writing lead 7 when the cap 70 is fitted to the barrel 6. In other words, the shape of the accommodating recess 72b may be configured in any way as long as the tip of the writing lead 7 is received within the accommodating recess 72b when the cap 70 is fitted, and the tip of the slider 9 is not received within the accommodating recess 72b but is locked and retracts. For example, the shape may be multiple protrusions extending inward that are formed on the inner circumferential surface of the cap 70 so as to cause the slider 9 to retract relative to the writing lead 7 when the cap 70 is fitted.

[0101] In the above-described embodiment, the slider 9 is biased forward by the cam abutment spring 18 to activate the lead advancing mechanism. However, the lead advancing member 72 of the cap 70 may also be applied to a mechanical pencil in which the slider is not biased forward. The mechanical pencil may or may not have a ball chuck. For example, the lead advancing member of the cap may be applied to a pipe-slide mechanical pencil in which a pipe-shaped lead guide, which is a slider attached to the tip member, advances as the lead protrudes with the click operation, and the lead guide retracts as the lead wears with writing.

[0102] 22 is an enlarged perspective view of the cap 70. The inner peripheral surface of the cap 70, specifically the inner peripheral surface near the open end, is provided with a plurality of positioning recesses 70b, specifically three, arranged at equal intervals along the circumferential direction. The positioning recesses 70b are recesses that open toward the rear and are formed in a bell-shaped curve when viewed radially outward from the central axis. That is, a convex curved surface 70ba is formed on the inner surface on the front side of the positioning recess 70b, and a concave curved surface 70bb is formed on the inner surface on the rear side of the positioning recess 70b.

[0103] FIG. 23 is an enlarged perspective view of the barrel 6. As shown in FIG. 23 and further in FIG. 2, the outer peripheral surface of the barrel 6 is provided with a plurality of positioning protrusions 6a, specifically three, arranged at equal intervals along the circumferential direction. The positioning protrusions 6a are protrusions that extend forward. A convex curved surface 6aa is formed on a portion of the outer surface on the front side of the positioning protrusion 6a. The convex curved surface 6aa of the positioning protrusion 6a is complementary to a portion of the convex curved surface 70ba of the positioning recess 70b. In other words, the positioning protrusions 6a and the positioning recess 70b have complementary portions.

[0104] As shown in FIG. 1 and FIG. 21(B), an annular magnet 80 is disposed inside the cap 70. The magnet 80 is, for example, a neodymium magnet. Instead of the annular magnet 80, multiple magnets may be disposed at equal intervals along the circumferential direction. On the other hand, the gripping portion 8 described above is a first magnetic body made of a magnetic material. The magnet 80 is disposed inside the cap 70 so that a magnetic attractive force acts between the magnet 80 and the gripping portion 8 when the cap 70 is fitted to the barrel 6.

[0105] When fitting the cap 70 to the barrel 6, typically, the barrel 6 is held with one hand and the cap 70 with the other, and the open end of the cap 70 is inserted into the barrel 6. When the cap 70 is inserted into the barrel 6 to a predetermined depth, the magnetic force acting between the gripping portion 8 and the magnet 80 pulls the cap 70 deeper. At this time, if the positioning protrusions 6a of the barrel 6 and the positioning recesses 70b of the cap 70 are aligned along the axial direction, the positioning protrusions 6a and the positioning recesses 70b will fit together without interfering with each other, and the barrel 6 and the cap 70 will be fitted together. On the other hand, there are cases where the positioning protrusions 6a of the barrel 6 and the positioning recesses 70b of the cap 70 are not aligned along the axial direction, i.e., are misaligned in the circumferential direction.

[0106] If the positioning protrusion 6a of the barrel 6 and the positioning recess 70b of the cap 70 are slightly misaligned in the circumferential direction, the magnetic attraction force causes the convex curved surface 6aa of the positioning protrusion 6a to come into contact with the concave curved surface 70bb of the positioning recess 70b. As a result, the positioning protrusion 6a and the positioning recess 70b work together to rotate the barrel 6 or the cap 70 around the central axis so that the positioning protrusion 6a and the positioning recess 70b fit together, and the barrel 6 and the cap 70 are fitted together.

[0107] If the positioning protrusions 6a of the barrel 6 and the positioning recesses 70b of the cap 70 are significantly misaligned in the circumferential direction, the convex curved surface 6aa of the positioning protrusion 6a and the concave curved surface 70bb of the positioning recesses 70b will not come into contact with each other even when subjected to magnetic attraction. Therefore, the positioning protrusions 6a and the positioning recesses 70b do not cooperate, and the barrel 6 and the cap 70 are not fitted together. Then, hold the cap 70 with one hand and rotate the cap 70 about the central axis until the convex curved surface 6aa of the positioning protrusion 6a comes into contact with the concave curved surface 70bb of the positioning recesses 70b. As a result, the positioning protrusions 6a and the positioning recesses 70b cooperate to rotate the barrel 6 or the cap 70 about the central axis so that the positioning protrusions 6a and the positioning recesses 70b fit together, and the barrel 6 and the cap 70 are fitted together.

[0108] The barrel and the cap are generally fitted together in a snap-fit ​​manner, with a protrusion formed on the inner peripheral surface of the cap climbing over a protrusion formed on the outer peripheral surface of the barrel. According to the above-described embodiment, the barrel 6 and the cap 70 are fitted together using magnetic attraction, so there is no need to press the cap 70 hard against the barrel 6. As a result, even if the cap 70 is inserted at an angle to the central axis of the barrel 6, there is no risk of the edge of the open end of the cap 70 damaging the outer peripheral surface of the barrel 6. Furthermore, even children or elderly people with weak strength can easily fit the barrel 6 and the cap 70 together.

[0109] Furthermore, if the outer surfaces of both the barrel 6 and the cap 70 are provided with identifying marks, designs, such as symbols, letters, or patterns, or distinctive shapes, the barrel 6 and the cap 70 can be correctly positioned in the rotational direction around the central axis. In short, the above-described embodiment provides a writing instrument that allows the cap to be accurately fitted to the barrel. Furthermore, since the magnetic force tends to become stronger the closer the relative distance, the barrel 6 and the cap 70 collide with force when the fitting is complete. As a result, the user can feel a pleasant clicking sensation and sound, and can recognize that the fitting has been completed reliably.

[0110] As shown in FIGS. 1, 2, and 4, a second magnetic body 81 made of a magnetic material may be disposed at the rear end of the barrel 6, i.e., the rear end of the rear barrel 3. This allows for magnetic attraction when fitting the cap 70 to the rear end of the barrel 6 for writing. In this case, a positioning protrusion 6a that cooperates with the positioning recess 70b of the cap 70 may be provided at the rear end of the barrel 6. In the above-described embodiment, the positioning protrusion 6a is formed on the outer peripheral surface of the barrel 6, and the positioning recess 70b is formed on the inner peripheral surface of the cap 70. However, a positioning recess may be formed on the outer peripheral surface of the barrel 6, and a positioning protrusion may be formed on the inner peripheral surface of the cap 70. The mechanical pencil 1 does not necessarily have to have the second magnetic body 81.

[0111] In the above-described embodiment, the magnet 80 is disposed on the cap 70 side, and the first magnetic body that is not a magnet is disposed on the barrel 6 side. However, it is also possible to dispose the first magnetic body on the cap 70 side, and dispose the magnet on the barrel 6 side, for example, inside the grip portion 8. However, since the grip portion 8 is exposed to the outside when the cap 70 is removed, it is preferable to dispose the first magnetic body on the barrel 6 side, in order to prevent surrounding magnetic bodies, such as a paper clip on a desk, from being attracted to the grip portion 8. Magnets may be disposed on both the barrel 6 and the cap 70. The first magnetic body may be provided on a part of the barrel 6 other than the grip portion 8.

[0112] Although three positioning protrusions 6a and three positioning recesses 70b are formed in the above-described embodiment, the number may be one, two, or four or more. The positioning protrusions 6a and the positioning recesses 70b may be configured arbitrarily as long as they cooperate with each other when slightly misaligned in the circumferential direction and the barrel 6 and the cap 70 are fitted together by rotating the barrel 6 or the cap 70 about the central axis. For example, the positioning protrusions 6a shown in FIG. 23 may be formed to be completely complementary to the positioning recesses 70b shown in FIG. 22.

[0113] The above-described fitting using magnetic attraction between the barrel and the cap may be applied not only to mechanical pencils but also to other writing implements, such as ballpoint pens, felt-tip pens, marker pens, fountain pens, thermochromic writing implements, etc. The positioning protrusion 6a and positioning recess 70b may be omitted, and the fitting between the barrel and the cap may simply be made to a writing implement using magnetic attraction.

[0114] FIG. 24 is a perspective view of the holding chuck 10, and FIG. 25 is a longitudinal cross-sectional view of the holding chuck 10. In FIG. 25, the left side is positioned to be the front side of the mechanical pencil 1. As described above, the holding chuck 10 is formed with a through-hole 10a extending along the axial direction. The holding chuck 10 has a cylindrical small-diameter portion 10b and a flange portion 10c provided on the outer peripheral surface of the rear end portion of the small-diameter portion 10b. A lead holding portion 10d that is narrower than the other portions is provided inside the front side of the through-hole 10a. A conical surface 10e that widens rearward is provided inside the through-hole 10a behind the lead holding portion 10d.

[0115] As shown in FIG. 24, the lead holding portion 10d of the through hole 10a is an elongated hole. Specifically, the cross-sectional shape of the lead holding portion 10d of the through hole 10a is a rounded rectangle. The lead holding portion 10d of the through hole 10a may be any elongated hole, and therefore the cross-sectional shape of the lead holding portion 10d may be oval, specifically, an ellipse or oval. The size of the elongated hole, for example, the length and aspect ratio in the case of a rounded rectangle, or the lengths of the major and minor axes in the case of an ellipse, is determined in advance through experiments or the like depending on the outer diameter or composition of the writing lead 7 typically used in mechanical pencils 1.

[0116] Because the lead holding portion 10d of the through hole 10a is an elongated hole, it is more susceptible to elastic deformation than a typical circular hole lead holding portion. That is, while an elongated hole is less susceptible to elastic deformation in the direction along the elongated shape, like a circular hole, it is more susceptible to elastic deformation in the direction perpendicular to the elongated shape. Therefore, even if there is some manufacturing variation in the outer diameter of the writing lead 7 or the size of the through hole in the holding chuck 10, this can be absorbed by elastic deformation in the direction perpendicular to the elongated shape. This makes it possible to provide a mechanical pencil that allows for more appropriate setting of the sliding resistance between the writing lead 7 and the holding chuck 10.

[0117] In a typical mechanical pencil, sliding contact between the lead and the retaining chuck occurs only when the lead is advanced by a knocking operation. On the other hand, as described above, in a mechanical pencil 1 equipped with a rotation drive mechanism and a lead advancing mechanism, sliding contact between the lead 7 and the retaining chuck 10 occurs not only when the lead 7 is advanced by a knocking operation but also during normal writing. Therefore, in order to ensure proper functioning of the rotation drive mechanism and the lead advancing mechanism, it is preferable to set the sliding resistance between the lead and the retaining chuck more precisely. In the mechanical pencil 1, the lead retaining portion 10d of the through-hole 10a is an elongated hole, which allows for more precise setting of the sliding resistance between the lead 7 and the retaining chuck 10.

[0118] The holding chuck 10 is made of an elastic material such as NBR, EPDM, fluororubber, or silicone rubber. A holding chuck 10 made of fluororubber is particularly preferable from the standpoint of creep resistance and chemical resistance. Although the writing lead 7 contains some oil components, the effects of the oil components can be further reduced by making the holding chuck 10 out of fluororubber. As a result, various types of oil components and their blends can be selected for the writing lead 7, making it possible to manufacture a wider variety of writing leads. In this case, the lead holding portion 10d does not have to be an elongated hole, and may have a typical circular cross-sectional shape.

[0119] In the above-described embodiment, the holding chuck 10 has a cylindrical small diameter portion 10b, but the holding chuck may be formed into a tapered shape as a whole. In short, the holding chuck 10 may have any outer shape as long as the core holding portion 10d of the through hole 10a is an elongated hole. [Explanation of symbols]

[0120] 1 mechanical pencil 2 front axle 3 rear axle 4 Tip member 6 shaft cylinder 6a Positioning protrusion 7 Writing lead 8 Gripping part (first magnetic body) 9 Slider 10 Holding chuck 10a through hole 10d Core holding part 11 Ball chuck 12 Relay member 17 Coil spring 18 Cam contact spring 19 Lead Case 20 Knock stick 21 Coil spring 30 Rotation drive mechanism 40 rotor 50 Dial cam member 51 Dial Cam 52 Rail cam member 53 Rail Cam 54 Delivery cam surface 55 steps 56 coil spring 60 Clutch mechanism 61 Input clutch cam 62 output clutch cam 63 Clutch cam surface 64 Transmission Cam 65 Extension cam 65c abutment 66 Clutch cam holder 70 Cap 70b Positioning recess 71 Cover cap 72 Core feeding member 72a Insertion hole 72b Storage recess 73 Cushion spring 80 Magnet 81 Second magnetic body

Claims

1. It has a barrel and a cap, a positioning protrusion is formed on one of the outer peripheral surface of the barrel and the inner peripheral surface of the cap, and a positioning recess is formed on the other of the outer peripheral surface of the barrel and the inner peripheral surface of the cap; When the barrel and the cap are about to be fitted together with the positioning protrusion and the positioning recess not aligned along the axial direction, the magnetic attraction acting between the barrel and the cap causes the positioning protrusion and the positioning recess to cooperate and rotate the barrel or the cap around the central axis, causing the positioning protrusion and the positioning recess to fit together, thereby fitting the barrel and the cap together. A writing implement in which a magnet is disposed on one of the barrel and the cap, and a magnetic body is disposed on the other of the barrel and the cap.

2. 2. The writing implement according to claim 1, wherein the positioning protrusion and the positioning recess have complementary portions.

3. 3. The writing implement according to claim 1, wherein a plurality of the positioning protrusions and the positioning recesses are provided at equal intervals along the circumferential direction.

4. 4. The writing implement according to claim 1, wherein the barrel is configured so that the cap can be fitted to the front end of the barrel by magnetic attraction.

5. 5. The writing implement according to claim 4, wherein the barrel is configured so that the cap can be fitted to the rear end of the barrel by magnetic attraction.

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