Multi-core writing instrument

Abstract

To provide a multi-core type writing instrument having a knock mechanism capable of performing a knock operation with a smaller knock amount.SOLUTION: A multi-refill writing instrument 400 includes a barrel 402, a first refill 403 and at least one second refill 404a disposed in the barrel 402, and the first refill 403 and a stretching mechanism 410. The first knock mechanism configured to selectively protrude the first refill 403 from the front end of the barrel 2 via the extension mechanism 410 by the knock operation and the second knock mechanism including the second refill 404a and configured to selectively protrude the second refill 404a from the front end of the barrel 2 by the knock operation are provided, and the extension mechanism 410 is configured to advance the first refill 403 such that the advance amount of the first refill 403 is larger than the knock amount by the knock operation.SELECTED DRAWING: Figure 9

Description

[Technical Field]

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

[0002] A multi-core writing instrument that is provided with a plurality of refills and can selectively protrude and retract a desired refill is known (for example, Patent Document 1). The multi-core writing instrument described in Patent Document 1 comprises a barrel, a first writing body and two second writing bodies provided at a predetermined interval along the inner circumferential surface of the barrel, a first knock member provided at the rear end of the first writing body so as to protrude rearward from the barrel and configured to selectively cause the first writing body to protrude from the front end of the barrel, and a second knock member provided at the rear end of the second writing body so as to protrude radially outward from the barrel and configured to selectively cause the second writing body to protrude from the front end of the barrel, and the protrusion of the first writing body is released by operating the first knock member.

[0003] According to the multi-core writing instrument described in Patent Document 1, the second writing body can be protruded by knocking two second knock members provided on the side of the barrel, i.e., by pressing the knock members forward. Because multiple second knock members are provided, it is necessary to perform the knocking operation while checking the second knock member corresponding to the desired second writing body. On the other hand, the first writing body can be protruded by knocking a single first knock member provided to protrude rearward from the barrel. Therefore, according to the multi-core writing instrument described in Patent Document 1, the first writing body can be easily and selectively protruded and retracted compared to the second writing body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-10952 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, a multi-core writing instrument requires a larger knock amount, i.e., a larger movement distance of the operating part, to change each writing body from a non-writing state to a writing state compared to a writing instrument with a single writing body. For example, when a first writing body is in a writing state, a second knock member corresponding to the second writing body is knocked to change the second writing body to a writing state. The second knock member advances, and the first writing body retracts. At this time, it is necessary to prevent interference between the retracting first writing body and the advancing second writing body within the tip of the tapered barrel. Therefore, in a multi-core writing instrument, the position of each writing body in the non-writing state, specifically the position of the writing part, is positioned further back compared to a writing instrument with a single writing body. As a result, a multi-core writing instrument requires a larger knock amount to change from a non-writing state to a writing state. Therefore, it is preferable for a multi-core writing instrument to have a knock mechanism that enables a knock operation with a smaller knock amount.

[0006] In particular, in the multi-core writing instrument described in Patent Document 1, the first knock member is arranged to protrude rearward from the barrel, and therefore the protrusion amount is greater than that of a writing instrument with a single writing element in order to ensure the required knock amount. Therefore, when the first knock member is knocked, the amount of hand and finger movement required to change the barrel is greater than when the second knock member arranged on the side of the barrel is knocked. Therefore, it is preferable to reduce the knock amount required to change from the non-writing state to the writing state. Furthermore, from the standpoint of design, it is preferable to reduce the amount of protrusion of the first knock member from the rear end of the barrel.

[0007] An object of the present invention is to provide a multi-core writing instrument having a knock mechanism that allows knocking operation with a smaller knock amount. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a multi-core writing instrument comprising a barrel, a first writing body and at least one second writing body arranged within the barrel, the first writing body and an extending mechanism, a first knock mechanism configured to selectively protrude the first writing body from the front end of the barrel via the extending mechanism by a knocking operation, and a second knock mechanism comprising the second writing body and configured to selectively protrude the second writing body from the front end of the barrel by a knocking operation, wherein the extending mechanism is configured to advance the first writing body so that the amount of advancement of the first writing body is greater than the amount of knocking by the knocking operation.

[0009] The extension mechanism may include an extension cam arranged in the barrel so as to be movable back and forth and rotatable about a central axis, the extension cam having a first cam portion and a second cam portion facing forward, a first cam receiving portion provided on an inner peripheral surface of the barrel and facing rearward, and a knock cam arranged in front of the extension cam in the barrel so as to be movable back and forth, the knock cam having a second cam receiving portion facing rearward, the first writing body advancing as the knock cam advances, and one of the first cam portion and the first cam receiving portion has a first inclined surface inclined along a circumferential direction, and the other has a first action capable of sliding along the first inclined surface. a second cam portion and a second cam receiving portion, one of which has a second inclined surface inclined in the opposite direction to the first inclined surface along the circumferential direction, and the other of which has a second acting portion that is slidable along the second inclined surface, and when the extension cam is advanced by a knock operation, the first cam portion and the first cam receiving portion cooperate to rotate the extension cam, and as the extension cam advances and rotates, the second cam portion and the second cam receiving portion cooperate to advance the knock cam, so that the advance amount of the first writing body is greater than the advance amount of the extension cam. In the first cam portion and the first cam receiver, one may have at least two first inclined surfaces symmetrically arranged about a central axis, and the other may have at least two first acting portions symmetrically arranged about a central axis, and in the second cam portion and the second cam receiver, one may have at least two second inclined surfaces symmetrically arranged about a central axis, and the other may have at least two second acting portions symmetrically arranged about a central axis, respectively. The extension cam may be cylindrical, and the first cam portion may be arranged radially outward from the second cam portion. The extension cam may be cylindrical, and the first cam portion and the second cam portion may be arranged on the same circumference. At least one of the first acting portion and the second acting portion may have a slope complementary to at least a portion of the corresponding first inclined surface or second inclined surface. At least one of the first acting portion and the second acting portion may have a convex curved surface.The pitch of the second inclined surfaces may be the same as or larger than the pitch of the first inclined surfaces. [Effects of the Invention]

[0010] According to the aspects of the present invention, a common effect is achieved in that a multi-core writing instrument having a knock mechanism that allows a knock operation with a smaller knock amount is provided. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a vertical cross-sectional view of a writing implement according to a first embodiment in a non-writing state. [Figure 2] FIG. 2 is a vertical cross-sectional view of the writing implement of FIG. 1 in a writing state. [Figure 3] FIG. 3 is an exploded view of the extension mechanism of the writing instrument of FIG. [Figure 4] 4 is a perspective view of an extension cam of the writing instrument of FIG. 1. FIG. [Figure 5] FIG. 5 is a bottom view of the extension cam of the writing instrument of FIG. [Figure 6] FIG. 6 is a perspective view of the knock cam of the writing instrument of FIG. [Figure 7] FIG. 7 is a perspective view of the rotor of the writing instrument of FIG. [Figure 8] 8 is a vertical cross-sectional view of the rear end portion of the rear barrel of the writing instrument of FIG. 1. FIG. [Figure 9] FIG. 9 is a schematic diagram showing the relationship between cams in the stretching mechanism of FIG. [Figure 10] FIG. 10 is a schematic diagram showing the operation of the stretching mechanism of FIG. 1 in stages. [Figure 11] FIG. 11 is a vertical cross-sectional view of the writing implement according to the second embodiment in a non-writing state. [Figure 12] FIG. 12 is a vertical cross-sectional view of the writing implement of FIG. 11 in a writing state. [Figure 13] FIG. 13 is an exploded view of the extension mechanism of the writing instrument of FIG. [Figure 14] 14 is a perspective view of the extension cam of the writing instrument of FIG. 11. FIG. [Figure 15] 15 is a bottom view of the extension cam of the writing instrument of FIG. 11. FIG. [Figure 16] 16 is a perspective view of the knock cam of the writing instrument of FIG. 11. FIG. [Figure 17] 17 is a perspective view of the rotor of the writing instrument of FIG. 11. FIG. [Figure 18] 18 is a vertical cross-sectional view of the rear end portion of the rear barrel of the writing instrument of FIG. [Figure 19] FIG. 19 is a vertical cross-sectional view of the writing implement according to the third embodiment in a non-writing state. [Figure 20] FIG. 20 is a vertical cross-sectional view of the writing implement of FIG. 19 in a writing state. [Figure 21] FIG. 21 is an exploded view of the extension mechanism of the writing instrument of FIG. [Figure 22] 22 is a perspective view of the extension cam of the writing instrument of FIG. 19. FIG. [Figure 23] 23 is a longitudinal cross-sectional view of the extension cam of the writing instrument of FIG. [Figure 24] 24 is a perspective view of the knock cam of the writing instrument of FIG. 19. FIG. [Figure 25] 25 is a perspective view of the rotor of the writing instrument of FIG. 19. FIG. [Figure 26] FIG. 26 is a perspective view of an extension cam of a writing implement according to a fourth embodiment. [Figure 27] 27(A) and 27(B) are respectively a front view and a side view of a writing implement according to a fifth embodiment in a non-writing state. [Figure 28] 28(A) is a cross-sectional view of the writing implement taken along line BB in FIG. 27(B), and FIG. 28(B) is a cross-sectional view of the writing implement taken along line AA in FIG. 27(A). [Figure 29] FIG. 29 is a vertical cross-sectional view of the writing implement in a writing state corresponding to FIG. 28(B). [Figure 30] Figure 30(A) is a cross-sectional view of the writing instrument taken along line CC in Figure 28(B), Figure 30(B) is a cross-sectional view of the writing instrument taken along line DD in Figure 28(B), and Figure 30(C) is a cross-sectional view of the writing instrument taken along line EE in Figure 28(B). [Figure 31]31 is a perspective view of the extension mechanism of the writing instrument of FIG. [Figure 32] Figures 32(A) to (D) are respectively a front view, a side view, a cross-sectional view of the rear axle along line GG in Figure 32(B), and a cross-sectional view of the rear axle along line FF in Figure 32(A). [Figure 33] 33(A) to 33(C) are a perspective view, a longitudinal cross-sectional view, and a plan view of the inner cylinder, respectively. [Figure 34] 34(A) and 34(B) are perspective and bottom views, respectively, of the extension cam of the writing instrument of FIG. 27. [Figure 35] 35(A) and 35(B) are respectively a perspective view and a longitudinal sectional view of the knock cam of the writing implement of FIG. 27. [Figure 36] 36 is a perspective view of the rotor of the writing instrument of FIG. 27. FIG. [Figure 37] 37(A) to 37(C) are a perspective view, a side view, and a bottom view, respectively, of one of the second knock members. [Figure 38] 38 is a perspective view of the spacer of the writing instrument of FIG. 27. FIG. [Figure 39] 39 is a perspective view of the clip of the writing instrument of FIG. 27. FIG. [Figure 40] FIG. 40 is a perspective view of the leaf spring of the clip. [Figure 41] FIG. 41 is a side view of the leaf spring of the clip. [Figure 42] FIG. 42 is a longitudinal cross-sectional view of the clip body of the clip. [Figure 43] 43(A) is a vertical cross-sectional view of the rear part of the writing instrument of FIG. 27 with the clip closed, and FIG. 43(B) is a vertical cross-sectional view of the rear part of the writing instrument of FIG. 27 with the clip open. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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.

[0013] Fig. 1 is a vertical cross-sectional view of a writing instrument 1 according to a first embodiment in a non-writing state, and Fig. 2 is a vertical cross-sectional view of the writing instrument 1 of Fig. 1 in a writing state. Also, Fig. 3 is an exploded assembly view of the extension mechanism 10 of the writing instrument 1 of Fig. 1. The writing instrument 1 is a knock-type writing instrument.

[0014] Writing instrument 1 has a cylindrical barrel 2 equipped with a front barrel 3 and a rear barrel 4, a cap 5 equipped with a clip 5a, a writing body refill 6 disposed within barrel 2 and equipped with a writing portion 6a at one end, and a spring 7 that biases refill 6 rearward. Crown 5 is fitted to the rear end of rear barrel 4, and the barrel 2 may also include crown 5. The rear end of front barrel 3 is inserted into the front end of rear barrel 4 and is fitted thereto by threading. Crown 5 does not have to have clip 5a. In this case, crown 5 may be formed integrally with rear barrel 4. In this specification, the side facing the writing portion in the axial direction of the writing instrument is defined as the "front" side, and the side opposite the writing portion is defined as the "rear" side.

[0015] An extension mechanism 10 is disposed inside the rear end of the barrel 2, i.e., the rear end of the rear barrel 4, and a knock button 8 is disposed behind the extension mechanism 10 as a knock operation unit. The extension mechanism 10 is a knock mechanism that moves the refill 6 back and forth within the barrel 2 by a knock operation. The crown 5 and knock button 8 may be collectively referred to as the extension mechanism 10. The state in which the writing part 6a is retracted into the barrel 2 is referred to as the non-writing state (Fig. 1), and the state in which the writing part 6a protrudes from the barrel 2 is referred to as the writing state (Fig. 2). The refill 6 and extension mechanism 10 may be collectively referred to as the knock mechanism.

[0016] The extension mechanism 10 mainly comprises an outer cam 20 provided on the inner peripheral surface of the barrel 2, specifically the inner peripheral surface of the rear barrel 4, a cylindrical extension cam 30, a cylindrical knock cam 40, and a cylindrical rotor 50. Within the barrel 2, the knock button 8, the extension cam 30, the knock cam 40, and the rotor 50 are arranged in this order from the rear end side.

[0017] Crown 5 is cylindrical and open at both ends. Clip 5a is provided to extend laterally from the outer peripheral surface of the rear end of crown 5. Four axially extending restriction grooves 5b are provided at equal intervals around the circumference on the inner peripheral surface of the front end of crown 5. Knock button 8 is cylindrical and closed at one end. Four axially extending restriction protrusions 8a are provided at equal intervals around the circumference on the outer peripheral surface of the front end of knock button 8. In the assembled state, each of the restriction protrusions 8a of knock button 8 is housed in one of the restriction grooves 5b of crown 5. Therefore, knock button 8 inserted through the front opening of crown 5 is restricted from rotating around its central axis while being movable back and forth.

[0018] FIG. 4 is a perspective view of the extension cam 30 of the writing instrument 1 of FIG. 1, and FIG. 5 is a bottom view of the extension cam 30 of the writing instrument 1 of FIG. 1. The extension cam 30 has a cylindrical cam main body 31 and a large diameter portion 32 that is larger in diameter than the cam main body 31. A rotating cam portion 33 is formed on the front end surface of the large diameter portion 32. The rotating cam portion 33 has two first inclined surfaces 34 that are inclined along the circumferential direction. The two first inclined surfaces 34 are inclined in the same direction and are arranged symmetrically with respect to the central axis of the extension cam 30. The rotating cam portion 33 constitutes the first cam portion.

[0019] A push-out cam portion 35 is formed in front of the cam body 31. The push-out cam portion 35 has two second inclined surfaces 36 that are inclined in the opposite direction to the first inclined surfaces 34 along the circumferential direction, and flat portions 37 provided at the apexes of the second inclined surfaces 36. The two second inclined surfaces 36 are inclined in the same direction and are arranged symmetrically with respect to the central axis of the extension cam 30. The push-out cam portion 35 constitutes the second cam portion.

[0020] As shown in Fig. 5, the rotating cam portion 33 is disposed radially outward from the pushing cam portion 35, and therefore the rotating cam portion 33 and the pushing cam portion 35 form a double cam surface adjacent to each other in the radial direction. The rotating cam portion 33 is disposed rearward from the pushing cam portion 35. The rotating cam portion 33 and the pushing cam portion 35 may also be disposed so as to be at the same position in the axial direction. As shown in Fig. 23 in another embodiment described later, the rotating cam portion 33 may also be disposed forward from the pushing cam portion 35.

[0021] In the extension cam 30, the first inclined surface 34 of the rotating cam portion 33 and the second inclined surface 36 of the pushing cam portion 35 have different inclination angles, i.e., different pitches. The pitch refers to the axial length of the inclined surface provided along the circumferential direction when the inclined surface is provided for one 360-degree revolution around the central axis. Specifically, in the writing instrument 1, the pitch of the second inclined surface 36 is twice the pitch of the first inclined surface 34.

[0022] FIG. 6 is a perspective view of the knock cam 40 of the writing instrument 1 of FIG. 1. Two first protrusions 41 extending in the axial direction are provided at equal intervals along the circumferential direction on the outer peripheral surface of the front side of the knock cam 40. A push-out cam receiver 42 is formed on the rear end surfaces of the two first protrusions 41. The push-out cam receiver 42 has a third inclined surface 43 inclined along the circumferential direction. The third inclined surface 43 is inclined in the same direction and at the same angle as the second inclined surface 36 of the extension cam 30 and is configured to cooperate with the second inclined surface 36. A second protrusion 44 extending in the axial direction is formed on the outer surface of the front side of the first protrusion 41. A series of cam surfaces 45 consisting of a plurality of repetitive peaks and valleys is formed on the front end surface of the knock cam 40. The front end surface of the second protrusion 44 forms part of the cam surface 45. The push-out cam receiver 42 constitutes the second cam receiver.

[0023] 7 is a perspective view of the rotor 50 of the writing instrument 1 of FIG. 1. A small diameter portion 51 is formed at the rear end of the rotor 50 and is inserted into the knock cam 40 to be used for centering. A protruding inner cam 53 is defined in front of the small diameter portion 51 by a large diameter portion 52. The inner cam 53 has four inner cam protrusions 54 extending in the axial direction. The four inner cam protrusions 54 are provided at equal intervals along the circumferential direction. A cam receiving surface 55 is provided on the rear end surface of the inner cam protrusion 54 as a slope inclined in the circumferential direction. The cam receiving surface 55 is inclined in the same direction and at the same angle as a portion of the cam surface 45 of the knock cam 40 and is configured to cooperate with the cam surface 45.

[0024] Figure 8 is a vertical cross-sectional view of the rear end portion of the rear barrel 4 of the writing instrument 1 of Figure 1. As described above, the protruding outer cam 20 is provided on the inner peripheral surface of the rear barrel 4. The outer cam 20 has two outer cam protrusions 23. The two outer cam protrusions 23 are provided at equal intervals along the circumferential direction. A rotating cam receiver 21 is formed on the rear end surface of the outer cam 20. A locking cam surface 22 is formed on the front end surface of the outer cam 20.

[0025] The rotating cam receiver 21 has a fourth inclined surface 24 that is inclined in the circumferential direction. The fourth inclined surface 24 is inclined in the same direction and at the same angle as the first inclined surface 34 of the rotating cam portion 33 of the extension cam 30, and is configured to cooperate with the first inclined surface 34. The locking cam surface 22 has a sawtooth-shaped sawtooth surface 25 and a groove 26 that extends rearward. In other words, each of the outer cam projections 23 has one fourth inclined surface 24 formed on its rear end surface, and two sawtooth surfaces 25 and a groove 26 between the two sawtooth surfaces 25 formed on its front end surface. A guide groove 27 is formed between the two outer cam projections 23. The rotating cam receiver 21 constitutes a first cam receiver.

[0026] The arrangement of each component of the writing instrument 1 will be described with reference to Figures 1 to 3. Extension cam 30 is inserted through the rear end opening of rear barrel 4. This positions extension cam portion 33 of extension cam 30 to cooperate with outer cam 20, particularly rotation cam receiver 21, inside barrel 2. Knock button 8 is inserted through the rear end opening of rear barrel 4, and crown 5 is fitted into the rear end opening of rear barrel 4 from above. This positions knock button 8 so that its front end face abuts the rear end face of extension cam 30. Knock cam 40 is inserted through the front end opening of rear barrel 4, and is inserted into the front end opening of extension cam 30. This positions push-out cam portion 35 of extension cam 30 to cooperate with push-out cam receiver 42 of knock cam 40. Rotor 50 is inserted through the front end opening of rear barrel 4, and small diameter portion 51 of rotor 50 is inserted into the front end opening of knock cam 40. As a result, the cam surface 45 of the knock cam 40 and the cam receiving surface 55 of the rotor 50 are arranged to cooperate with each other. The front shaft 3, on which the refill 6 and the spring 7 are arranged, is screwed onto the rear shaft 4 so that the refill 6 is inserted into the front end opening of the rotor 50.

[0027] FIG. 9 is a schematic diagram showing the relationship between the cams of the stretching mechanism 10 of FIG. 1. That is, FIG. 9 is a schematic diagram showing the positional relationships between the crown 5, knock button 8, outer cam 20, stretching cam 30, knock cam 40, and rotor 50, particularly the positional relationships between the rotating cam portion 33 and the rotating cam receiver 21, and the positional relationships between the pushing cam portion 35 and the pushing cam receiver 42. In the figure, the upper side is the rear side of the writing instrument 1, and the lower side is the front side of the writing instrument 1. In FIG. 9, the cams or protrusions of each component are expanded in the circumferential direction, ignoring their radial and axial positions, dimensions, and shapes, in order to clarify the relative positions of each component. For example, in the stretching cam 30, the large diameter portion 32 on which the rotating cam portion 33 with the first inclined surface 34 is formed, and the cam body 31 on which the pushing cam portion 35 with the second inclined surface 36 is formed are shown as a single unit, and the overall length of the first inclined surface 34 is also shortened. In the knock cam 40, the first protrusion 41 and the second protrusion 44 each having the third inclined surface 43 are shown integrally in schematic form.

[0028] The second protrusion 44 of the knock cam 40 is disposed within the guide groove 27 between the outer cam protrusions 23. Therefore, the knock cam 40 is movable back and forth while its rotation around the central axis is restricted. The first inclined surface 34 of the extension cam 30 and the fourth inclined surface 24 of the outer cam 20 are disposed so as to abut against each other, and the second inclined surface 36 of the extension cam 30 and the third inclined surface 43 of the knock cam 40 are disposed so as to abut against each other. Figure 9 shows the writing instrument 1 in a non-writing state, and therefore each of the inner cam protrusions 54 of the rotor 50 is disposed in the corresponding groove 26 or guide groove 27. The cam surface 45 of the knock cam 40 and the cam receiving surface 55 of the rotor 50 are disposed so as to abut against each other.

[0029] The rotor 50 is biased rearward via the refill 6 biased rearward by the spring 7. The knock cam 40 is biased rearward via the abutment between the cam receiving surface 55 of the rotor 50 biased rearward and the cam surface 45 of the knock cam 40. The extension cam 30 is biased rearward via the abutment between the third inclined surface 43 of the knock cam 40 biased rearward and the second inclined surface 36 of the extension cam 30. The knock button 8 is biased rearward via the abutment between the rear end surface of the extension cam 30 biased rearward and the front end surface of the knock button 8.

[0030] 10A and 10B are schematic diagrams showing the operation of the stretching mechanism 10 in Fig. 1 in stages, and showing the transition from a non-writing state to a writing state. Fig. 10A is the same as Fig. 9 and shows the stretching mechanism 10 in the writing instrument 1 in the non-writing state.

[0031] From the state shown in FIG. 10(A), a knock operation is performed by pressing the knock button 8 forward. The advancement of the knock button 8 due to the knock operation advances the extension cam 30. When the extension cam 30 advances, the rotating cam portion 33 of the extension cam 30 and the rotating cam receiving portion 21 of the outer cam 20 cooperate to rotate the extension cam 30 around the central axis relative to the rear axle 4. Specifically, the first inclined surface 34 slides downward and leftward in the figure along the fourth inclined surface 24, causing the extension cam 30 to advance and rotate simultaneously. Meanwhile, as the extension cam 30 advances and rotates, the push-out cam portion 35 of the extension cam 30 and the push-out cam receiving portion 42 of the knock cam 40 cooperate to advance the knock cam 40. Specifically, the third inclined surface 43 slides relatively along the second inclined surface 36, causing the knock cam 40 to advance. The knock cam 40 is restricted from rotating around the central axis because the second protrusion 44 is disposed in the guide groove 27 of the outer cam 20. As the knock cam 40 advances, the rotor 50, and therefore the refill 6, are pressed against the biasing force of the spring 7 and advance together.

[0032] In short, the cooperation of the rotating cam portion 33 of the extension cam 30 and the rotating cam receiver 21 of the outer cam 20 causes the extension cam 30 to move in a rotational direction. As the extension cam 30 rotates, the push-out cam portion 35 of the extension cam 30 and the push-out cam receiver 42 of the knock cam 40 cooperate to increase the amount of advancement of the knock cam 40 compared to the amount of advancement of the extension cam 30. The amount of increase in the amount of advancement of the knock cam 40 can be geometrically designed by the inclination angle or pitch of the first inclined surface 34 of the rotating cam portion 33 or the fourth inclined surface 24 of the rotating cam receiver 21, which determine the amount of rotation (rotation angle) of the extension cam 30, and the inclination angle or pitch of the second inclined surface 36 of the push-out cam portion 35 or the third inclined surface 43 of the push-out cam receiver 42, which cause advancement according to the amount of rotation.

[0033] For example, if the pitch of the second inclined surface 36 of the extrusion cam portion 35 is the same as the pitch of the first inclined surface 34 of the rotating cam portion 33, the amount of movement of the refill 6 is twice the amount of knocking caused by the knock operation, i.e., twice the amount of movement of the knock button 8. Also, if the pitch of the second inclined surface 36 of the extrusion cam portion 35 is twice the pitch of the first inclined surface 34 of the rotating cam portion 33, the amount of movement of the refill 6 is three times the amount of knocking caused by the knock operation.

[0034] Therefore, when the knock button 8 is pressed by a knock operation from the state shown in FIG. 10(A) and the knock button 8 is advanced by a distance D11, the rotor 50 and therefore the refill 6 advance by a distance D21, which is greater than the distance D11 (FIG. 10(B)). When the knock button 8 is further pressed and advanced by a distance D12, the rotor 50 and therefore the refill 6 advance by a distance D22, which is greater than the distance D21 (FIG. 10(C)). Note that in the state shown in FIG. 10(C), the inner cam protrusion 54 of the rotor 50 is positioned in the corresponding groove portion 26 or guide groove 27, and therefore the rotor 50 is restricted from rotating around the central axis. Also, as described above, the rotor 50 is constantly biased backward by the spring 7.

[0035] From the state shown in FIG. 10(C), further pressing the knock button 8 advances the rotor 50. When the inner cam projection 54 passes the groove 26 or the guide groove 27, the restriction on the rotation of the rotor 50 is released (FIG. 10(D)). At this time, the cam surface 45 of the knock cam 40 and the cam receiving surface 55 of the rotor 50 cooperate to rotate the rotor 50 around the central axis. That is, under the axial force due to the advance caused by the knock operation and the axial force due to the biasing force of the spring 7, the cam receiving surface 55, which is the slope of the rotor 50, is pressed against the cam surface 45, which is composed of a repetition of multiple peaks and valleys, and receives a circumferential component force. Since the rotation of the knock cam 40 is restricted, the rotor 50 rotates. The rotation of the rotor 50 stops when the inner cam projection 54 engages with the sawtooth bevel 25 that constitutes the engaging cam surface 22 (FIG. 10(E)), and the writing instrument 1 enters the writing state.

[0036] When the knocking operation is performed again on the writing instrument 1 in the writing state, the rotor 50 moves forward, releasing the engagement between the inner cam protrusion 54 and the locking cam surface 22. At this time, the cam surface 45 of the knock cam 40 and the cam receiving surface 55 of the rotor 50 cooperate again, causing the rotor 50 to rotate. As a result, each of the inner cam protrusions 54 of the rotor 50 is positioned in the groove portion 26 or the guide groove 27, and the biasing force of the spring 7 moves the rotor 50, and thus the refill 6, back, so that the writing instrument 1 enters the non-writing state. At this time, the extension cam 30 rotates in the opposite direction to when changing from the non-writing state to the writing state, returning to the state shown in Figure 10(A).

[0037] As described above, according to the stretching mechanism 10, the amount of advancement of the staple-refill 6 can be increased more than the amount of knocking caused by the knocking operation, so that the knocking operation can be performed with a smaller amount of knocking.

[0038] The stretching mechanism according to another embodiment will be described below.

[0039] Fig. 11 is a vertical cross-sectional view of a writing instrument 100 according to a second embodiment in a non-writing state, and Fig. 12 is a vertical cross-sectional view of the writing instrument 100 of Fig. 11 in a writing state. Also, Fig. 13 is an exploded assembly view of the extension mechanism of the writing instrument 100 of Fig. 11. The writing instrument 100 is a knock-type writing instrument.

[0040] Writing instrument 100 differs from writing instrument 1 according to the first embodiment in the shapes of rear barrel 104 and extension mechanism 110. Extension mechanism 110 mainly has an outer cam 120 provided on the inner peripheral surface of rear barrel 104, an extension cam 130, a knock cam 140, and a rotor 150.

[0041] FIG. 14 is a perspective view of the extension cam 130 of the writing instrument 100 of FIG. 11, and FIG. 15 is a bottom view of the extension cam 130 of the writing instrument 100 of FIG. 11. The extension cam 130 has a cylindrical cam body 131. A rotation cam portion 133 and a push-out cam portion 135 are formed on the front end surface of the cam body 131. Specifically, the annular end surface of the cam body 131 in the bottom view of FIG. 15 is divided into four equal parts, and the rotation cam portion 133 and the push-out cam portion 135 are each formed by opposing arcs. Therefore, the rotation cam portion 133 and the push-out cam portion 135 are arranged on the same circumference.

[0042] The rotating cam portion 133 has two first inclined surfaces 134 that are inclined along the circumferential direction. The two first inclined surfaces 134 are inclined in the same direction and are arranged symmetrically with respect to the central axis of the extension cam 130. The rotating cam portion 133 constitutes a first cam portion. The pushing cam portion 135 has two second inclined surfaces 136 that are inclined along the circumferential direction in the opposite direction to the first inclined surfaces 134. The two second inclined surfaces 136 are inclined in the same direction and are arranged symmetrically with respect to the central axis of the extension cam 130. The pushing cam portion 135 constitutes a second cam portion. In the extending cam 130, the first inclined surfaces 134 and the second inclined surfaces 136 are arranged on the same circumference and are continuously connected. In the writing instrument 100, the pitch of the second inclined surfaces 136 is twice the pitch of the first inclined surfaces 134.

[0043] FIG. 16 is a perspective view of the knock cam 140 of the writing instrument 100 of FIG. 11. Two first protrusions 141 extending rearward from the front end are provided on the outer peripheral surface of the knock cam 140 at equal intervals along the circumferential direction. Push-out cam receivers 142 are formed on the rear end surfaces of the two first protrusions 141. The push-out cam receivers 142 have third inclined surfaces 143 that are inclined along the circumferential direction. The third inclined surfaces 143 are inclined in the same direction and at the same angle as the second inclined surfaces 136 of the extension cam 130, and are configured to cooperate with the second inclined surfaces 136. A series of cam surfaces 145 consisting of a repetition of multiple peaks and valleys is formed on the front end surface of the knock cam 140. The push-out cam receivers 142 constitute the second cam receivers.

[0044] Figure 17 is a perspective view of the rotor 150 of the writing instrument 100 of Figure 11. A small diameter portion 151 is formed at the rear end of the rotor 150 and is inserted into the knock cam 140 to be used for centering. A protruding inner cam 153 is defined in front of the small diameter portion 151 by a large diameter portion 152. The inner cam 153 has four inner cam protrusions 154 extending in the axial direction. The four inner cam protrusions 154 are provided at equal intervals along the circumferential direction. A cam receiving surface 155 is provided on the rear end surface of the inner cam protrusion 154 as a slope inclined in the circumferential direction. The cam receiving surface 155 is inclined in the same direction and at the same angle as a portion of the cam surface 145 of the knock cam 140 and is configured to cooperate with the cam surface 145.

[0045] Figure 18 is a vertical cross-sectional view of the rear end portion of rear barrel 104 of writing instrument 100 of Figure 11. A protruding outer cam 120 is provided on the inner peripheral surface of rear barrel 104. Outer cam 120 has two outer cam protrusions 123. The two outer cam protrusions 123 are provided at equal intervals along the circumferential direction. A rotating cam receiver 121 is formed on the rear end surface of outer cam 120. A locking cam surface 122 is formed on the front end surface of outer cam 120.

[0046] The rotating cam receiver 121 has a fourth inclined surface 124 that is inclined in the circumferential direction. The fourth inclined surface 124 is inclined in the same direction and at the same angle as the first inclined surface 134 of the rotating cam portion 133 of the extension cam 130, and is configured to cooperate with the first inclined surface 134. The locking cam surface 122 has a sawtooth-shaped sawtooth surface 125 and a groove 126 that extends toward the rear. In other words, each of the outer cam projections 123 has one fourth inclined surface 124 formed on its rear end surface and two sawtooth surfaces 125 and a groove 126 between the two sawtooth surfaces 125 formed on its front end surface. A guide groove 127 is formed between the two outer cam projections 123. The rotating cam receiver 121 constitutes a first cam receiver.

[0047] Because the writing instrument 100 has the extension mechanism 110, the advancement amount of the refill 6 can be increased more than the amount of knocking caused by the knocking operation, based on the principle described above with reference to Figure 10. In other words, when the extension cam 130 is advanced by the knocking operation, the rotating cam portion 133 and the rotating cam receiving portion 121 work together to rotate the extension cam 130, and as the extension cam 130 advances and rotates, the push-out cam portion 135 and the push-out cam receiving portion 142 work together to advance the knock cam 140. As a result, the advancement amount of the refill 6 can be increased more than the advancement amount of the extension cam 130.

[0048] Fig. 19 is a vertical cross-sectional view of a writing instrument 200 according to a third embodiment in a non-writing state, and Fig. 20 is a vertical cross-sectional view of the writing instrument 200 of Fig. 19 in a writing state. Also, Fig. 21 is an exploded view of the extension mechanism 210 of the writing instrument 200 of Fig. 19. The writing instrument 200 is a knock-type writing instrument.

[0049] The writing instrument 200 differs from the writing instrument 1 according to the first embodiment in the shapes of the knock button 208, rear barrel 204, and extension mechanism 210. Furthermore, the writing instrument 200 has an inner tube 209 instead of a crown. The inner tube 209 is disposed inside the rear barrel 204, and the barrel 202 may be collectively referred to as the barrel 202. An outer cam similar to the outer cam 20 or outer cam 120 described above is provided on the inner circumferential surface of the barrel 202, specifically on the inner circumferential surface of the inner tube 209, and a detailed description thereof will be omitted. The extension mechanism 210 mainly has an outer cam 220, an extension cam 230, a knock cam 240, and a rotor 250.

[0050] 22 is a perspective view of the extension cam 230 of the writing instrument 200 of FIG. 19, and FIG. 23 is a longitudinal cross-sectional view of the extension cam 230 of the writing instrument 200 of FIG. 19. The extension cam 230 has a cylindrical cam main body 231 and a large-diameter portion 232 that is larger in diameter than the cam main body 231. A rotating cam portion 233 is formed on the front end surface of the large-diameter portion 232. The rotating cam portion 233 has two first inclined surfaces 234 that are inclined in the circumferential direction, and a flat portion 237 provided at the apex of the first inclined surfaces 234. The two first inclined surfaces 234 are inclined in the same direction and are arranged symmetrically with respect to the central axis of the extension cam 230. The rotating cam portion 233 constitutes the first cam portion.

[0051] A push-out cam portion 235 is formed in front of the cam body 231. The push-out cam portion 235 has two second inclined surfaces 236 that are inclined in the opposite direction to the first inclined surfaces 234 along the circumferential direction, and a flat portion 237 provided at the apex of the second inclined surfaces 236. The two second inclined surfaces 236 are inclined in the same direction and are arranged symmetrically with respect to the central axis of the extension cam 230. The push-out cam portion 235 constitutes a second cam portion. Since the rotation cam portion 233 is arranged radially outward from the push-out cam portion 235, the rotation cam portion 233 and the push-out cam portion 235 constitute a double cam surface that is adjacent in the radial direction. The rotation cam portion 233 is arranged forward of the push-out cam portion 235. In the writing instrument 200, the pitch of the second inclined surfaces 236 is twice the pitch of the first inclined surfaces 234.

[0052] FIG. 24 is a perspective view of the knock cam 240 of the writing instrument 200 of FIG. 19. Two first protrusions 241 extending in the axial direction are provided on the outer peripheral surface of the knock cam 240 at equal intervals along the circumferential direction. Push-out cam receivers 242 are formed on the rear end surfaces of the two first protrusions 241. The push-out cam receivers 242 have third inclined surfaces 243 inclined along the circumferential direction. The third inclined surfaces 243 are inclined in the same direction and at the same angle as the second inclined surfaces 236 of the extension cam 230 and are configured to cooperate with the second inclined surfaces 236. Two second protrusions 244 extending in the axial direction are formed on the outer peripheral surface of the front end of the knock cam 240. The two second protrusions 244 are provided at equal intervals along the circumferential direction and are provided at positions corresponding to the first protrusions 241 in the circumferential direction. A series of cam surfaces 245 consisting of a plurality of repetitive peaks and valleys is formed on the front end surface of the knock cam 240. The front end surface of the second protrusion 244 forms part of the cam surface 245. The push-out cam receiving portion 242 forms the second cam receiving portion.

[0053] 25 is a perspective view of the rotor 250 of the writing instrument 200 of FIG. 19. A small diameter portion 251 is formed at the rear end of the rotor 250 and is inserted into the knock cam 240 to be used for centering. A protruding inner cam 253 is defined in front of the small diameter portion 251 by a large diameter portion 252. The inner cam 253 has four inner cam protrusions 254 extending in the axial direction. The four inner cam protrusions 254 are provided at equal intervals along the circumferential direction. A cam receiving surface 255 is provided on the rear end surface of the inner cam protrusion 254 as a slope inclined in the circumferential direction. The cam receiving surface 255 is inclined in the same direction and at the same angle as a portion of the cam surface 245 of the knock cam 240 and is configured to cooperate with the cam surface 245.

[0054] In the writing instrument 200, as shown in Figures 22 and 23, a rotation support portion 238 having a hemispherical tip is provided at the rear end of the cam body 231. In the above-described embodiments, for example, the first embodiment, the knock button 8 and the extension cam 30 are in contact with each other such that the annular front end surface of the knock button 8 and the annular rear end surface of the extension cam 30 abut over the entire circumference. When the knock button 8 is knocked, the extension cam 30 rotates around the central axis while being pressed forward by the knock button 8 and urged rearward by the spring 7, as described above. At this time, the annular rear end surface of the extension cam 30 slides against the annular front end surface of the knock button 8, generating resistance.

[0055] On the other hand, in this embodiment, when the knock button 208 is knocked, the extension cam 230 rotates around the central axis while being pressed by the knock button 208. At this time, the extension cam 230 rotates with respect to the inner surface of the rear end face of the knock button 208, with the apex of the hemispherical rotation support portion 238 of the extension cam 230 as a fulcrum. In other words, when the extension cam 230 rotates, the knock button 208 and the extension cam 230 come into contact only at the apex of the hemispherical rotation support portion 238, and the contact is point-like. Therefore, according to the extension cam 230 of this embodiment, it is possible to reduce resistance during rotation compared to the extension cams of the above-mentioned embodiments.

[0056] The shape of the portion of the rotation support 238 that comes into contact with other components during rotation may be arbitrarily configured as long as it reduces resistance, i.e., reduces the contact area. For example, it may be conical rather than hemispherical.

[0057] Because the writing instrument 200 has the extension mechanism 210, the advancement amount of the refill 6 can be increased more than the amount of knocking caused by the knocking operation, based on the principle described above with reference to Figure 10. In other words, when the extension cam 230 is advanced by the knocking operation, the rotating cam portion 233 and the rotating cam receiving portion 221 work together to rotate the extension cam 230, and as the extension cam 230 advances and rotates, the push-out cam portion 235 and the push-out cam receiving portion 242 work together to advance the knock cam 240. As a result, the advancement amount of the refill 6 can be increased more than the advancement amount of the extension cam 230.

[0058] 26 is a perspective view of an extension cam 330 of a writing instrument according to the fourth embodiment. The writing instrument according to the fourth embodiment differs from the writing instrument 200 according to the third embodiment only in the shape of the extension cam 330. Specifically, the extension cam 330 differs from the extension cam 230 of the writing instrument 200 in the shapes of the rotation cam portion 333 and the rotation support portion 338. Therefore, a description of the other configurations of the writing instrument will be omitted.

[0059] The extension cam 330 has a cylindrical cam body 331 and a large diameter portion 332 that is larger in diameter than the cam body 331. A rotating cam portion 333 is formed on the front end surface of the large diameter portion 332. The rotating cam portion 333 has two convex curved surfaces 334 that curve in the circumferential direction. The two convex curved surfaces 334 are arranged symmetrically with respect to the central axis of the extension cam 330. The rotating cam portion 333 constitutes a first cam portion.

[0060] A push-out cam portion 335 is formed in front of the cam body 331. The push-out cam portion 335 has two second inclined surfaces 336 that are inclined in the circumferential direction and a flat portion 337 provided at the apex of the second inclined surfaces 336. The two second inclined surfaces 336 are inclined in the same direction and are arranged symmetrically with respect to the central axis of the extension cam 330. The push-out cam portion 335 constitutes a second cam portion. Since the rotating cam portion 333 is arranged radially outward from the pushing cam portion 335, the rotating cam portion 333 and the pushing cam portion 335 constitute a double cam surface that is adjacent in the radial direction. The rotating cam portion 333 is arranged forward of the pushing cam portion 335.

[0061] In the extension cam of the above-described embodiment, the rotating cam portion that cooperates with the rotating cam receiver has a first inclined surface that slopes in the circumferential direction. However, in this embodiment, the rotating cam portion 333 has a convex curved surface 334 instead of the inclined surface. As described with reference to FIG. 10 , the rotating cam portion is configured to slide in cooperation with the rotating cam receiver. The convex curved surface 334 can slide against the fourth inclined surface of the rotating cam receiver, just like the inclined surface. That is, when the extension cam 330 is advanced by a knocking operation, the rotating cam portion 333 and the rotating cam receiver 221 cooperate to rotate the extension cam 330. As the extension cam 330 advances and rotates, the push cam portion 335 and the push cam receiver 242 cooperate to advance the knock cam 240. As a result, the advancement amount of the staple-refill 6 can be increased more than the advancement amount of the extension cam 330.

[0062] The rotation support portion 338 of the extension cam 330 is formed in a cylindrical shape. Therefore, the extension cam 330 rotates while the circular rear end surface of the rotation support portion 338 abuts against the inner surface of the rear end surface of the knock button 208.

[0063] 27(A) and 27(B) are respectively a front view and a side view of a writing instrument 400 according to a fifth embodiment in a non-writing state, FIG. 28(A) is a cross-sectional view of the writing instrument 400 taken along line BB in FIG. 27(B), and FIG. 28(B) is a cross-sectional view of the writing instrument 400 taken along line AA in FIG. 27(A). Also, FIG. 29 is a vertical cross-sectional view of the writing instrument 400 in a writing state corresponding to FIG. 28(B). Furthermore, FIG. 30(A) is a cross-sectional view of the writing instrument 400 taken along line CC in FIG. 28(B), FIG. 30(B) is a cross-sectional view of the writing instrument 400 taken along line DD in FIG. 28(B), and FIG. 30(C) is a cross-sectional view of the writing instrument 400 taken along line EE in FIG. 28(B). FIG. 31 is a perspective view of the extension mechanism 410 of the writing instrument 400 of FIG. 27. The writing instrument 400 is a multi-core writing instrument.

[0064] The writing instrument 400 has a barrel 402, a first refill 403 and a second refill 404a, 404b arranged within the barrel 402, a first knock member 405 arranged at the rear end of the first refill 403 so as to protrude rearward from the barrel 402, second knock members 460a, 460b arranged at the rear ends of the second refills 404a, 404b so as to protrude radially outward from the barrel 402, and a clip 490.

[0065] The barrel 402 has a front barrel 407, a rear barrel 480 arranged rearward of the front barrel 407, and an inner barrel 470 fixed to the rear barrel 480. The front barrel 407 and the rear barrel 480 are connected by press-fitting, bonding, or screwing. For example, the front barrel 407 and the rear barrel 480 are connected by screwing a female screw formed on the inner peripheral surface of the front side of the rear barrel 480 into a male screw formed on the outer peripheral surface of the rear side of the front barrel 407. The clip 490 has a leaf spring 491 and a clip body 496.

[0066] In this embodiment, the first refill 403 is a refill for one ballpoint pen, and the second refills 404a and 404b are refills for two ballpoint pens. The first refill 403 and the second refills 404a and 404b are arranged at a predetermined interval along the inner circumferential surface of the barrel 402. In this embodiment, the circumferential intervals between adjacent refills are approximately equal.

[0067] The first knock member 405 is configured to selectively protrude the first refill 403 from the front end of the barrel 402. The second knock members 460a and 460b have second refills 404a and 404b as second knock mechanisms and are configured to selectively protrude the second refills 404a and 404b from the front end of the barrel 402. Specifically, when the first knock member 405 is knocked, the first refill 403 protrudes, and when the second knock members 460a and 460b are knocked, the second refills 404a and 404b protrude. The nibs of the first refill 403 and the second refills 404a and 404b move radially inward along the inner circumferential surface of the barrel 402 and protrude from the front end of the barrel 402. This allows writing to be performed using one of the three refills selectively.

[0068] The protrusion of the first refill 403 is released by knocking the first knock member 405 or the second knock members 460a, 460b. The protrusion of the second refills 404a, 404b is released by knocking the first knock member 405 or the second knock members 460a, 460b of the non-protruding second refills 404a, 404b. Therefore, the protrusion of the first refill 403 and the second refills 404a, 404b can be released by knocking any one of the knock members, greatly improving the operability of the writing instrument 400. In this specification, "the protrusion of the refill is released" means that the nib of the refill protruding from the front end of the barrel 402 retracts into the barrel 402.

[0069] The first refill 403 has a first ink containing tube 409 and a first tip 411 which is a writing portion. The second refills 404a, 404b have a second ink containing tube 412 and a second tip 414 which is a writing portion. The first tip 411 is connected to the first ink containing tube 409. The second tip 414 is connected to the second ink containing tube 412.

[0070] The first ink containing tube 409 and the two second ink containing tubes 412 typically contain inks of different colors. By disposing the first knock member 405 rearward of the second knock members 460a and 460b, the length of the first ink containing tube 409 can be made longer than the second ink containing tube 412. As a result, the ink filling volume of the first ink containing tube 409 can be made greater than the ink filling volume of the second ink containing tube 412. Therefore, for example, by storing black ink, which is a commonly used color, in the first ink containing tube 409, the life of the writing instrument 400 can be extended or the frequency of ink refill replacement can be reduced. Furthermore, to achieve a similar effect, the radial length of the first ink containing tube 409 may be made longer than that of the second ink containing tube 412 so that the ink filling volume of the first ink containing tube 409 is greater than that of the second ink containing tube 412.

[0071] The first knock member 405 has a first knock mechanism, which includes a first refill 403, a knock button 408, and an extension mechanism 410. The extension mechanism 410 may be referred to as including the knock button 408. The extension mechanism 410 is a knock mechanism that moves the first refill 403 in the front-to-rear direction within the barrel 402 by a knock operation that presses the knock button 408 forward. The extension mechanism 410 has an inner barrel 470 equipped with an outer cam 420, a cylindrically formed extension cam 430, a knock cam 440, and a rotor 450. Within the barrel 402, the knock button 408, the extension cam 430, the knock cam 440, and the rotor 450 are arranged in this order from the rear end side. Two regulating protrusions 408a extending in the axial direction are provided at equal intervals along the circumferential direction on the outer peripheral surface of the front end of the knock button 408.

[0072] A spring 416 is disposed between the knock button 408 and the extension cam 430, and the knock button 408 is biased rearward. The extension cam 430, the knock cam 440, and the rotor 450 are configured to move in the axial direction within the inner cylinder 470. As will be described in detail later, by pressing and rotating the rotor 450 via the knock cam 440, the first refill 403 can be made to protrude and retract from the front end of the barrel 402.

[0073] FIGS. 32(A) to 32(D) are a front view, a side view, a cross-sectional view of rear body 480 taken along line GG in FIG. 32(B), and a cross-sectional view of rear body 480 taken along line FF in FIG. 32(A), respectively. Two slide holes 481 are formed in the outer peripheral surface of rear body 480 to allow second knock members 460a, 460b to slide in the axial direction. Slide holes 481 extend in the axial direction. A first protrusion 482 and a second protrusion 485 are formed in the inner peripheral surface of rear body 480. As shown in FIGS. 30(A) and 30(B) and 32(C) and 32(D), first protrusion 482 and second protrusion 485 protrude radially inward and extend in the axial direction. A pair of first slide portions 486 extending in the axial direction are provided on both circumferential side surfaces of first protrusion 482. A first step 487 is provided at the front end of first sliding portion 486. A through hole 483 is formed at the rear end of rear shaft 480, allowing knock cam 440, described later, to protrude from rear shaft 480. A locking portion 488 is provided at the rear end of rear shaft 480. A press-fit hole 489 extending in the longitudinal direction is provided at the rear end of rear shaft 480, into which leaf spring 491 of clip 490 is inserted.

[0074] 33(A) to 33(C) are a perspective view, a longitudinal cross-sectional view, and a plan view, respectively, of inner cylinder 470. Inner cylinder 470 has an accommodating portion 471 that accommodates first knock member 405 and two partition walls 472 that cooperate with the inner circumferential surface of rear barrel 480 to define an accommodating portion that accommodates second knock members 460a and 460b. Accommodating portion 471 and partition walls 472 each extend in the front-rear direction. A second sliding portion 473 is provided on a side surface of partition walls 472 adjacent to second knock members 460a and 460b. A second step portion 474 is provided at the front end of second sliding portion 473.

[0075] The accommodation portion 471 is formed with a through hole 475 extending in the front-rear direction. The inner surface of the through hole 475 is formed with two guide grooves 477 extending rearward from the front end, two restriction grooves 478 extending forward from the rear end, and two outer cam protrusions 423. The guide grooves 477 accommodate a second protrusion 444 of the knock cam 440, which will be described later. Furthermore, when the first refill 403 is in the retracted state, the guide grooves 477 accommodate an inner cam protrusion 454 of the rotor 450, which will be described later. The restriction grooves 478 accommodate a restriction protrusion 408a of the knock button 408. The inner cylinder 470 may be integral with the rear barrel 480.

[0076] A rotating cam receiver 421 is formed on the rear end surface of the outer cam projection 423. Two fourth inclined surfaces 424 inclined in the circumferential direction are formed on the rotating cam receiver 421. A locking cam surface 422 is formed on the front end surface of the inner cylinder 470. The rotating cam receiver 421 and the locking cam surface 422 may be collectively referred to as the outer cam 420. A locking claw 476 is formed on the rear end of the inner cylinder 470. The inner cylinder 470 is inserted into the rear axle 480 and fixed by the locking claw 476 engaging with a locking portion 488 of the rear axle 480. The rotating cam receiver 421 constitutes a first cam receiver.

[0077] 30(A), with inner barrel 470 fixed to rear barrel 480, each of partitions 472 of inner barrel 470 abuts against a corresponding second protrusion 485 of rear barrel 480. Second knock members 460a, 460b are housed in a space defined by rear barrel 480 and inner barrel 470, and slide back and forth along corresponding first sliding portion 486 and second sliding portion 473. When second refills 404a, 404b protrude from barrel 402, first step portion 487 and second step portion 474 engage with the rear ends of second knock members 460a, 460b, and the writing state is maintained. In other words, the corresponding first sliding portion 486 and second sliding portion 473, and the first step portion 487 and second step portion 474 have the same or corresponding shapes so that the second knock members 460a, 460b can slide back and forth and engage with each other.

[0078] 34(A) and 34(B) are a perspective view and a bottom view, respectively, of the extension cam 430 of the writing instrument 400 of FIG. 27. The extension cam 430 has a cylindrical cam body 431. At the front end of the cam body 431, a rotating cam portion 433 is formed on the outer portion obtained by equally dividing the radial thickness, i.e., the wall thickness, of the cam body 431. The rotating cam portion 433 has two first inclined surfaces 434 that are inclined in the circumferential direction. The two first inclined surfaces 434 are inclined in the same direction and are arranged symmetrically with respect to the central axis of the extension cam 430. The rotating cam portion 433 constitutes the first cam portion.

[0079] At the front end of the cam body 431, a push-out cam portion 435 is formed on the inner portion of an equal-divided radial thickness. The push-out cam portion 435 has two second inclined surfaces 436 that are inclined in the opposite direction to the first inclined surfaces 434 along the circumferential direction. The two second inclined surfaces 436 are inclined in the same direction and are arranged symmetrically with respect to the central axis of the extension cam 430. The push-out cam portion 435 constitutes the second cam portion. In the writing instrument 400, the pitch of the second inclined surfaces 436 is the same as the pitch of the first inclined surfaces 434.

[0080] 35(A) and 35(B) are a perspective view and a longitudinal cross-sectional view, respectively, of the knock cam 440 of the writing instrument 400 of FIG. 27. The knock cam 440 has a generally cylindrical shape. Two first protrusions 441 extending in the axial direction are provided on the outer peripheral surface of the front side of the knock cam 440 at equal intervals along the circumferential direction. Push-out cam receivers 442 are formed on the rear end surfaces of the two first protrusions 441. The push-out cam receivers 442 have third inclined surfaces 443 inclined along the circumferential direction. The third inclined surfaces 443 are inclined in the same direction as the second inclined surfaces 436 of the extension cam 430 and are configured to cooperate with the second inclined surfaces 436. Three second protrusions 444 extending in the axial direction are formed in front of the first protrusions 441. The three second protrusions 444 are provided at equal intervals along the circumferential direction. A cam surface 445 consisting of a plurality of repetitions of peaks and valleys is formed on the front end surface of the knock cam 440. The push-out cam receiving portion 442 constitutes a second cam receiving portion.

[0081] The second protrusion 444 is configured to slide axially within the guide groove 477 of the inner cylinder 470 when the knock cam 440 moves axially. That is, the knock cam 440 and the inner cylinder 470 are configured to restrict the circumferential rotation of the knock cam 440. An accommodation space 446 is formed inside the knock cam 440 to accommodate a small diameter portion 451 of the rotor 450, which will be described later.

[0082] Figure 36 is a perspective view of the rotor 450 of the writing instrument 400 of Figure 27. A small diameter section 451 is formed at the rear end of the rotor 450, and is inserted into the knock cam 440 and used for centering. A protruding inner cam 453 is formed on a large diameter section 452 in front of the small diameter section 451. The inner cam 453 has three inner cam protrusions 454 extending in the axial direction. The three inner cam protrusions 454 are provided at equal intervals along the circumferential direction. A cam receiving surface 455 is provided on the rear end surface of the inner cam protrusion 454 as a slope inclined in the circumferential direction. The cam receiving surface 455 is inclined in the same direction and at the same angle as a portion of the cam surface 445 of the knock cam 440, and is configured to cooperate with the cam surface 445.

[0083] The portion of the cam receiving surface 455 on which the inner cam protrusion 454 is provided cooperates with cam surfaces 466 of second knock members 460a and 460b, which will be described later. An insertion portion 456 is provided at the front end of the rotor 450. The rear end of the first ink containing tube 409 is press-fitted into the insertion portion 456. This fixes the first ink containing tube 409 to the rotor 450.

[0084] Cam receiving surface 455 is configured to receive axial and circumferential forces from cam surface 445 when knock cam 440 moves forward. Therefore, when cam surface 445 presses cam receiving surface 455 as knock cam 440 moves forward, rotor 450 rotates in the circumferential direction due to the circumferential force. Meanwhile, because second protrusion 444 is housed in guide groove 477 of inner cylinder 470, knock cam 440 is restricted from rotating in the circumferential direction.

[0085] When the inner cam protrusions 454 are housed in the guide grooves 477 of the inner cylinder 470, one of the three inner cam protrusions 454 engages with the locking cam surface 422 of the inner cylinder 470 in the axial direction as the rotor 450 rotates in the circumferential direction due to the advancement of the knock cam 440. Furthermore, when the inner cam protrusions 454 are axially engaged with the locking cam surface 422, the inner cam protrusions 454 are disengaged from the locking cam surface 422 as the rotor 450 rotates in the circumferential direction due to the advancement of the knock cam 440, and thereafter receive a further circumferential force from the locking cam surface 422 and are housed in the guide grooves 477. In other words, the inner cylinder 470 and the rotor 450 are configured to engage with or disengage from each other in the axial direction as the rotor 450 rotates in the circumferential direction due to the advancement of the knock cam 440.

[0086] 37(A) to 37(C) are a perspective view, a side view, and a bottom view, respectively, of one of the second knock members 460a. The second knock member 460b is formed as a mirror image of the second knock member 460a. The second knock member 460a has an elongated shape. The second knock member 460a has a main body portion 461 extending in the front-rear direction, a fitting portion 462 formed in front of the main body portion 461, and an operating portion 463 formed in the rear of the main body portion 461. The fitting portion 462 fits into the second ink containing tube 412, thereby fixing the second ink containing tube 412 to the second knock member 460a. The main body portion 461 is formed with a biasing surface 464 against which a second spring 418 (described later) abuts. As shown in FIG. 27, operating portion 463 protrudes radially outward from barrel 402 when writing instrument 400 is in an assembled state, and can therefore be operated with a finger.

[0087] A cam portion 465 is formed on one side of the main body portion 461. A cam surface 466 that cooperates with a cam receiving surface 455 of the rotor 450 is formed on the front end of the cam portion 465. The cam surface 466 and the cam receiving surface 455 are configured so that when the second knock member 460a advances, the cam receiving surface 455 receives axial and circumferential forces from the cam surface 466. Therefore, when the cam surface 466 presses the cam receiving surface 455 as the second knock members 460a and 460b advance, the rotor 450 rotates in the circumferential direction due to the circumferential force. Meanwhile, because the operating portion 463 of the second knock members 460a and 460b abuts against the side wall of the slide hole 481 of the rear axle 480, circumferential rotation of the second knock members 460a and 460b is restricted.

[0088] A pressing protrusion 467 and a contact protrusion 468 are formed on the bottom surface of the main body 461. The pressing protrusion 467 is located forward of the contact protrusion 468. When the writing instrument 400 is in an assembled state, the pressing protrusion 467 and the contact protrusion 468 protrude radially inward from the barrel 402 and extend axially. The contact protrusion 468 is pressed by the inner cam protrusion 454 of the rotor 450 when the protrusion of the second knock member 460a is released by a knock operation of the first knock member 405. The inner cam protrusion 454 and the contact protrusion 468 are configured to receive axial and radial forces from each other when in contact. Furthermore, when the protrusion of the second refill 404a is released by a knock operation of the second knock member 460b of the second refill 404b that is not protruding, the contact protrusion 468 is pressed by the pressing protrusion 467 of the second knock member 460b of the second refill 404b that is not protruding. The contact protrusion 468 and the pressing protrusion 467 are configured to receive axial and radial forces from each other when they come into contact.

[0089] As shown in FIG. 28, the writing instrument 400 further includes a first spring 417, a second spring 418, and a spacer 419 that supports the first spring 417 and the second spring 418.

[0090] FIG. 38 is a perspective view of the spacer 419 of the writing instrument 400 of FIG. 27. The spacer 419 includes a spacer 419a and a plurality of protruding spring guides 419b extending rearward from a cylindrical portion. The spacer 419a has a cylindrical shape and three through holes formed therein. The first through hole 419c and two second through holes 419d are spaced at predetermined intervals along the inner circumferential surface of the spacer 419a. In this embodiment, the circumferential intervals between adjacent through holes are approximately equal. The first ink containing tube 409 extends through the first through hole 419c and is fixed to the rotor 450. The second ink containing tube 412 extends through the second through hole 419d and is fixed to the second knock members 460a and 460b. The area of ​​the first through hole 419c is larger than the area of ​​the second through hole 419d. This allows the first ink containing tube 409 to be thicker than the second ink containing tube 412, and therefore the ink filling amount of the first ink containing tube 409 can be greater than the ink filling amount of the second ink containing tube 412.

[0091] The first spring 417 is disposed between the rear surface of the spacer 419a and the front end of the rotor 450 so as to surround the first ink containing tube 409 in the circumferential direction, and biases the rotor 450 and therefore the first refill 403 rearward. The second spring 418 is disposed between the rear surface of the spacer 419a and the biasing surfaces 464 of the second knock members 460a and 460b so as to surround the second ink containing tube 412 in the circumferential direction, and biases the second knock members 460a and 460b and therefore the second refills 404a and 404b rearward.

[0092] Below, we will explain the principle by which the first refill 403 and the second refills 404a, 404b protrude from the front end of the barrel 402, and the principle by which the protrusion of the first refill 403 and the second refills 404a, 404b is released by the first knock member 405 or the second knock member 460a, 460b.

[0093] First, the principle by which the first refill 403 protrudes from the front end of the barrel 402 will be described.

[0094] In the retracted state, the inner cam protrusion 454 of the rotor 450 is housed in the guide groove 477 of the inner cylinder 470. From this state, a knock operation is performed to press the knock button 408 forward against the biasing force of the first spring 417. The knock operation moves the knock button 408 forward, thereby advancing the extension cam 430. When the extension cam 430 is advanced, the rotating cam portion 433 of the extension cam 430 and the rotating cam receiving portion 421 of the outer cam 420 cooperate to rotate the extension cam 430 about the central axis relative to the inner cylinder 470 and, ultimately, the rear shaft 480. That is, based on the principle described above with reference to FIG. 10 , the first inclined surface 434 slides along the fourth inclined surface 424, and the extension cam 430 advances and rotates simultaneously. On the other hand, as the extension cam 430 advances and rotates, the push cam portion 435 of the extension cam 430 and the push cam receiving portion 442 of the knock cam 440 cooperate to advance the knock cam 440. That is, the third inclined surface 443 slides relatively along the second inclined surface 436, causing the knock cam 440 to advance. Note that the second protrusion 444 is disposed in the guide groove 477 of the inner cylinder 470, so that the rotation of the knock cam 440 around the central axis is restricted. Furthermore, as the knock cam 440 advances, the rotor 450, and therefore the first refill 403, are pressed against the biasing force of the first spring 417 and advance together.

[0095] In short, the cooperation of the rotating cam portion 433 of the extension cam 430 and the rotating cam receiving portion 421 of the outer cam 420 causes the extension cam 430 to move in a rotational direction. The rotation of the extension cam 430 causes the cooperation of the pushing cam portion 435 of the extension cam 430 and the pushing cam receiving portion 442 of the knock cam 440, increasing the amount of advancement of the knock cam 440 compared to the amount of advancement of the extension cam 430.

[0096] At this time, knock cam 440 and rotor 450 receive axial and circumferential forces from each other via cam surface 445 and cam receiving surface 455. Thereafter, when the rear end of inner cam projection 454 passes the front end of locking cam surface 422, the restriction on circumferential rotation of rotor 450 is released, and rotor 450 rotates circumferentially due to the circumferential force. Meanwhile, knock cam 440 does not rotate circumferentially because its circumferential rotation is restricted by second projection 444 being housed in guide groove 477.

[0097] In this state, when the pressure on the knock button 408 is released, the extension cam 430, the knock cam 440, and the rotor 450 move backward due to the biasing force of the first spring 417. At this time, one of the inner cam protrusions 454 of the rotor 450, which has rotated in the circumferential direction, engages with the locking cam surface 422 of the inner cylinder 470 in the axial direction. This engagement prevents the rotor 450 from moving backward, so the first refill 403 fixed to the rotor 450 remains protruding from the front end of the shaft cylinder 402.

[0098] The principle by which the protrusion of first refill 403 is released by first knock member 405 will be described below.

[0099] In the protruding state, the inner cam protrusion 454 of the rotor 450 axially engages with the locking cam surface 422 of the inner cylinder 470. When the knock cam 440 is advanced from this state via the knock button 408 and the extension cam 430 against the biasing force of the first spring 417, the cam surface 445 of the knock cam 440 presses the cam receiving surface 455 of the rotor 450, and the rotor 450 advances together with the knock cam 440. At this time, the knock cam 440 and the rotor 450 are subjected to axial and circumferential forces from each other via the cam surface 445 and the cam receiving surface 455. Thereafter, when the rear end of the inner cam protrusion 454 passes the front end of the locking cam surface 422, the restriction on the circumferential rotation of the rotor 450 is released, and the rotor 450 rotates circumferentially due to the circumferential force. On the other hand, the knock cam 440 does not rotate in the circumferential direction because the second protrusion 444 is housed in the guide groove 477 of the inner cylinder 470 and thus its rotation in the circumferential direction is restricted.

[0100] When the pressure on the knock button 408 is released in this state, the extension cam 430, the knock cam 440, and the rotor 450 move backward due to the biasing force of the first spring 417, and the inner cam protrusion 454 that has rotated in the circumferential direction is accommodated in the guide groove 477. At this time, the first refill 403 fixed to the rotor 450 also moves backward, so the protrusion of the first refill 403 is released.

[0101] The principle by which the protrusion of the first refill 403 is released by the second knock members 460a and 460b will be described below.

[0102] In the protruding state, the inner cam protrusions 454 of the rotor 450 axially engage with the locking cam surfaces 422 of the inner cylinder 470. At this time, the cam portions 465 of the second knock members 460a, 460b are positioned rearward of the inner cam protrusions 454 of the rotor 450, and the circumferential position of the cam portions 465 is the same as that of one of the inner cam protrusions 454.

[0103] When second knock members 460a, 460b are advanced from this state against the biasing force of second spring 418, cam surfaces 466 of second knock members 460a, 460b come into contact with cam receiving surface 455 of rotor 450, and rotor 450 advances together with second knock members 460a, 460b. At this time, second knock members 460a, 460b and rotor 450 receive axial and circumferential forces from each other via cam surface 466 and cam receiving surface 455. Thereafter, when the rear end of inner cam projection 454 passes the front end of locking cam surface 422, the restriction on circumferential rotation of rotor 450 is released, and rotor 450 rotates circumferentially due to the circumferential force. On the other hand, the second knock members 460a, 460b do not rotate in the circumferential direction because their rotation in the circumferential direction is restricted by the operation portion 463 abutting against the side wall of the slide hole 481 of the rear barrel 480. The inner cam protrusion 454 that has rotated in the circumferential direction is accommodated in the guide groove 477 by the biasing force of the first spring 417. At this time, the extension cam 430, the rotor 450, and the knock cam 440 move backward, so that the first refill 403 fixed to the rotor 450 also moves backward, and the protrusion of the first refill 403 is released.

[0104] The principle behind how the second refills 404a and 404b protrude from the front end of the barrel 402 will be described below.

[0105] From the immersed state, the second knock members 460a, 460b are advanced against the biasing force of the second spring 418. Thereafter, when the rear ends of the second knock members 460a, 460b clear the second step portion 474 of the second sliding portion 473 of the inner cylinder 470, the operating portions 463 of the second knock members 460a, 460b drop radially inward.

[0106] When the second knock members 460a, 460b are released in this state, the biasing force of the second spring 418 causes the rear ends of the second knock members 460a, 460b to engage with the second step portion 474 in the axial direction. This engagement prevents the second knock members 460a, 460b from moving backward, so that the second refills 404a, 404b fixed to the second knock members 460a, 460b remain protruding from the front end of the barrel 402.

[0107] The following describes the principle by which the protrusion of second refill 404b is released by first knock member 405. The principle by which the protrusion of second refill 404a is released by first knock member 405 is also the same.

[0108] In the protruding state, the second knock member 460b is engaged with the inner cylinder 470 in the axial direction. At this time, the inner cam protrusion 454 of the rotor 450 is located rearward of the contact protrusion 468 of the second knock member 460b. The inner cam protrusion 454 and the contact protrusion 468 partially overlap in the circumferential direction.

[0109] When the knock cam 440 is advanced from this state via the knock button 408 and the extension cam 430 against the biasing force of the first spring 417, the cam surface 445 of the knock cam 440 comes into contact with the cam receiving surface 455 of the rotor 450, and the rotor 450 advances together with the knock cam 440. After that, when the inner cam protrusion 454 of the rotor 450 comes into contact with the contact protrusion 468 of the second knock member 460b, the contact protrusion 468 receives a radially outward force from the inner cam protrusion 454, and the engagement between the second knock member 460b and the inner cylinder 470 is released. After that, the second knock member 460b moves backward due to the biasing force of the second spring 418, and the second refill 404b fixed to the second knock member 460b also moves backward, and the protrusion of the second refill 404b is released.

[0110] The principle by which the protrusion of second refill 404b is released by second knock member 460a will be described below. The principle by which the protrusion of second refill 404a is released by second knock member 460b is also the same.

[0111] In the protruding state, the second knock member 460b engages with the inner tube 470 in the axial direction. At this time, the pressing protrusion 467 of the second knock member 460a of the second refill 404a that does not protrude is located rearward of the contact protrusion 468 of the second knock member 460b. Furthermore, the pressing protrusion 467 of the second knock member 460a and the contact protrusion 468 of the second knock member 460b partially overlap in the circumferential direction.

[0112] When second knock member 460a of second knock member 404a is advanced from this state against the biasing force of second spring 418, pressing protrusion 467 of second knock member 460a comes into contact with contact protrusion 468 of second knock member 460b. At this time, contact protrusion 468 of second knock member 460b receives a radially outward force from pressing protrusion 467 of second knock member 460a, and therefore, second knock member 460b is disengaged from inner tube 470. Thereafter, second knock member 460b is moved backward by the biasing force of second spring 418, and second refill 404b fixed to second knock member 460b is also moved backward, and the protrusion of second refill 404b is released.

[0113] Because the writing instrument 400 has the extension mechanism 410, it is possible to increase the amount of advancement of the first refill 403 more than the amount of knocking caused by the knocking operation, based on the principle described above with reference to Figure 10. In other words, when the extension cam 430 is advanced by the knocking operation, the rotating cam portion 433 and the rotating cam receiving portion 421 work together to rotate the extension cam 430, and as the extension cam 430 advances and rotates, the push-out cam portion 435 and the push-out cam receiving portion 442 work together to advance the knock cam 440. As a result, it is possible to increase the amount of advancement of the first refill 403 more than the amount of advancement of the extension cam 430.

[0114] Although writing instrument 400 has two second refills 404a and 404b as second writing bodies, it may also have one or three or more second refills. In short, as a multi-core writing instrument, it may include a first writing body and at least one second writing body arranged in a barrel, a first knocking mechanism including the first writing body and an extending mechanism and configured to selectively cause the first writing body to protrude from the front end of the barrel via the extending mechanism by a knocking operation, and a second knocking mechanism including a second writing body and configured to selectively cause the second writing body to protrude from the front end of the barrel by a knocking operation, and the extending mechanism may be configured to advance the first writing body so that the advancement amount of the first writing body is greater than the knocking amount by the knocking operation.

[0115] According to all of the above-described embodiments, a knock operation can be performed with a smaller knock amount, thereby realizing a more compact knock mechanism. In particular, in the above-described extension mechanism, the first cam portion is disposed radially outward from the second cam portion, or the first cam portion and the second cam portion are disposed on the same circumference. Therefore, compared to a configuration in which the first cam portion and the second cam portion are disposed at both ends of the extension cam in the front-rear direction, the overall length of the extension cam and therefore the extension mechanism can be shortened. Therefore, the refill can be made longer or the writing instrument can be made more compact. Furthermore, for example, if the knock operation portion protrudes rearward from the rear end of the barrel, the amount of protrusion can be reduced.

[0116] Except for the convex curved surface 334 of the rotating cam portion 333 of the extension cam 330 of the writing implement according to the fourth embodiment, in other embodiments, the first inclined surface of the rotating cam portion of the extension cam cooperates with the fourth inclined surface of the rotating cam receiver of the outer cam, and the second inclined surface of the push cam portion of the extension cam cooperates with the third inclined surface of the push cam receiver of the knock cam. Here, the inclined surface only needs to be inclined in the circumferential direction, and does not necessarily have to be an inclined surface in the strict sense. Therefore, the inclined surface includes curved surfaces, i.e., convex curved surfaces and concave curved surfaces.

[0117] The first inclined surface of the rotating cam portion, which is the first cam portion, and the fourth inclined surface of the rotating cam receiver, which is the first cam receiver, have at least partially complementary inclined surfaces. The second inclined surface of the pushing cam portion, which is the second cam portion, and the third inclined surface of the pushing cam receiver, which is the second cam receiver, have at least partially complementary inclined surfaces.

[0118] The rotating cam receiver may have a first acting portion, instead of the fourth inclined surface, that is slidable along the first inclined surface of the rotating cam portion. On the other hand, the rotating cam portion may have a first acting portion, instead of the first inclined surface, that is slidable along the fourth inclined surface of the rotating cam receiver. In other words, one of the rotating cam portion and the rotating cam receiver may have a first inclined surface that is inclined along the circumferential direction, and the other may have a first acting portion that is slidable along the first inclined surface. Similarly, the push cam receiver may have a second acting portion, instead of the third inclined surface, that is slidable along the second inclined surface of the push cam portion. On the other hand, the push cam portion may have a second acting portion, instead of the second inclined surface, that is slidable along the third inclined surface of the push cam receiver. In other words, one of the push cam portion and the push cam receiver may have a second inclined surface that is inclined along the circumferential direction, and the other may have a second acting portion that is slidable along the second inclined surface.

[0119] The first and second operating portions may be convex curved surfaces, such as the convex curved surface 334 of the rotating cam portion 333 described above. They may be configured in any manner as long as they can slide along the corresponding first or second inclined surfaces. The pitch of the second inclined surfaces may be the same as or larger than the pitch of the first inclined surfaces. By making the pitch of the second inclined surfaces larger than the pitch of the first inclined surfaces, a knock operation can be performed with a smaller knock amount. There may be two first inclined surfaces and corresponding first operating portions, as in the above-described embodiment, or one or three or more second inclined surfaces and corresponding second operating portions. When there are two or more first inclined surfaces and corresponding first operating portions, and two or more second inclined surfaces and corresponding second operating portions, it is preferable that they are arranged at equal intervals along the circumferential direction, i.e., symmetrically around the central axis of the writing instrument or barrel. It is preferable to provide two or more first inclined surfaces and corresponding first action portions, and two or more second inclined surfaces and corresponding second action portions, since this stabilizes the rotation of the extension cam compared to the case where there is only one.

[0120] In short, according to the above-described embodiment, there is provided a knock-type writing instrument that can be switched between a writing state and a non-writing state by a knock operation, the knock-type writing instrument comprising: a barrel; an extension cam that is arranged within the barrel so as to be movable back and forth and rotatable about a central axis, and has a first cam portion and a second cam portion facing forward; a first cam receiving portion that is provided on the inner peripheral surface of the barrel and faces rearward; a knock cam that is arranged within the barrel in front of the extension cam so as to be movable back and forth, and has a second cam receiving portion facing rearward; and a writing body that advances as the knock cam advances. and the other has a first acting part that can slide along a first inclined surface, and the second cam part and second cam receiving part have a second inclined surface that is inclined in the opposite direction to the first inclined surface along the circumferential direction, and the other has a second acting part that can slide along the second inclined surface, and when the extension cam is advanced by a knock operation, the first cam part and the first cam receiving part work together to rotate the extension cam, and as the extension cam advances and rotates, the second cam part and the second cam receiving part work together to advance the knock cam, so that the advancement amount of the writing body is greater than the advancement amount of the extension cam.

[0121] In the above-described embodiment, the knock button provided at the rear end of the writing instrument may be configured as an erasing member for erasing handwriting made by the writing instrument. The refill, which is the writing body of the above-described writing instrument, may contain thermochromic ink. In this case, the writing instrument is a thermochromic writing instrument, and the handwriting made by the writing instrument can be thermochromic due to the frictional heat generated when rubbed by the friction body, which is the erasing member. Note that the writing body may also be a ballpoint pen containing thermochromic ink, a mechanical pencil containing a thermochromic lead, a pencil holder, or the like. The writing instrument may also contain eraser-erasable ink that can be erased with an eraser.

[0122] Here, thermochromic ink refers to ink that maintains a predetermined color (first color) at room temperature (e.g., 25°C), changes to a different color (second color) when heated to a predetermined temperature (e.g., 60°C), and then returns to the original color (first color) when cooled to a predetermined temperature (e.g., -5°C). In a writing instrument using thermochromic ink, the second color is made colorless, and "erasing" refers to heating a line drawn in the first color (e.g., red) to make it colorless. Therefore, a frictional body acting as an erasing part rubs against the writing surface on which the line was drawn, generating frictional heat, thereby changing the drawn line to colorless, i.e., erasing it. Naturally, the second color may be a color other than colorless.

[0123] Fig. 39 is a perspective view of clip 490 of writing instrument 400 of Fig. 27. Clip 490 has a leaf spring 491 and a clip body 496.

[0124] Fig. 40 is a perspective view of the leaf spring 491 of the clip 490, and Fig. 41 is a side view of the leaf spring 491 of the clip 490. Fig. 42 is a vertical cross-sectional view of the clip body 496 of the clip 490.

[0125] 40 and 41, leaf spring 491 is a leaf spring formed in a generally U-shape that opens forward. Leaf spring 491 can be formed from various plate-shaped elastic materials, but is preferably formed from a metal material, particularly stainless steel. Leaf spring 491 comprises a first end 492 attached to barrel 402, specifically, to press-fit hole 489 of rear barrel 480, a second end 493 attached to clip body 496, and a convex curved portion 494 connecting first end 492 and second end 493. Saw-like sawtooth protrusions 492a are formed on both side surfaces of first end 492, and saw-like sawtooth protrusions 493a are formed on both side surfaces of second end 493.

[0126] Referring to FIG. 41 , curved portion 494 is formed by bending a plate-shaped member constituting a leaf spring to have approximately the same radius of curvature. Curved portion 494 is formed in an arc shape with a central angle of 180 degrees or more. Meanwhile, first end 492 extends in the same direction as and approximately parallel to second end 493. An extension line of second end 493 is approximately equal to a tangent line at the connection portion with curved portion 494. Meanwhile, the portion of curved portion 494 connected to first end 492 has an inflection point in relation to the convex portion of curved portion 494 that protrudes outward. In other words, curved portion 494, formed in an arc shape with a central angle of 180 degrees or more, has a concave inflection portion 495 that protrudes inward on the first end 492 side. A convex proximity point 494a is provided at a position 180 degrees from the tangent point between the extension line of second end 493 and curved portion 494, i.e., on the opposite side of the tangent point. The proximal point 494a of the curved portion 494 is the point furthest from the extension of the outer surface of the first end 492, and is spaced a distance L from the extension.

[0127] Referring to FIG. 42, when clip 490 is attached to writing instrument 400, clip body 496 has a front end formed with a convex ball portion 496a that prevents clip 490 from slipping out when an article is gripped by clip 490. Clip body 496 has a longitudinally extending attachment hole 497 formed therein so that leaf spring 491 can be inserted therein. Clip body 496 has a receiving hole 496b formed at the front end of attachment hole 497. Receiving hole 496b is formed on the inner surface of receiving hole 496b, and a fitting protrusion 496c is formed thereon. Note that a similar fitting protrusion (not shown) is also formed on the inner surface of press-fit hole 489 of rear barrel 480. Clip body 496 has a rear end formed with a wall-shaped abutment portion 498 defined by attachment hole 497. Abutment portion 498 is configured to be positioned opposite barrel tube 402 when clip 490 is attached to writing instrument 400.

[0128] The clip 490 is assembled by inserting the leaf spring 491 into the mounting hole 497 of the clip body 496. Specifically, the second end 493 of the leaf spring 491 is inserted into the receiving hole 496b of the clip body 496. At this time, the gentler slopes of the saw-tooth protrusions 493a on both sides of the second end 493 abut against the fitting protrusions 496c, and the saw-tooth protrusions 493a move forward inside the receiving hole 496b while climbing over the fitting protrusions 496c. Therefore, there is little resistance in the direction of inserting the leaf spring 491 into the clip body 496. On the other hand, in the direction of pulling the leaf spring 491 out of the clip body 496, the steeper slopes of the saw-tooth protrusions 493a abut against the fitting protrusions 496c, and the saw-tooth protrusions 493a are tightly engaged with the fitting protrusions 496c. Therefore, there is a large resistance in the direction of pulling out the leaf spring 491, and the leaf spring 491 cannot be removed unless the clip main body 496 is destroyed.

[0129] The first end 492 of the leaf spring 491 is inserted into the press-fit hole 489 of the rear axle 480. At this time, the gentler slopes of the saw-tooth projections 492a on both sides of the first end 492 abut against the fitting projections, and the saw-tooth projections 492a move forward within the press-fit hole 489 while climbing over the fitting projections. Therefore, there is little resistance in the direction of inserting the leaf spring 491 into the rear axle 480. On the other hand, in the direction of pulling the leaf spring 491 out of the rear axle 480, the steeper slopes of the saw-tooth projections 492a abut against the fitting projections, and the saw-tooth projections 492a are tightly engaged with the fitting projections. Therefore, there is great resistance in the direction of pulling out the leaf spring 491, and the leaf spring 491 cannot be removed unless the rear axle 480 is destroyed. In short, the saw blade protrusion 492a of the first end 492 and the mating protrusion of the press-fit hole 489, and the saw blade protrusion 493a of the second end 493 and the mating protrusion 496c of the receiving hole 496b are configured to allow progression in the insertion direction but not to allow progression in the withdrawal direction.

[0130] 43(A) is a vertical cross-sectional view of the rear portion of writing instrument 400 of FIG. 27 with clip 490 in a closed state, i.e., with no article clamped therein, and FIG. 43(B) is a vertical cross-sectional view of the rear portion of writing instrument 400 of FIG. 27 with clip 490 in an open state. Referring to FIG. 43(A), clip 490 is attached to barrel 402. Specifically, as described above, first end 492 of leaf spring 491 is inserted into press-fit hole 489 of rear barrel 480. In this state, the point on leaf spring 491 that is closest to the central axis of barrel 402 is proximity point 494a of curved portion 494 described above. proximity point 494a is the point farthest from an extension line of first end 492; in other words, it is the point farthest from an extension line of press-fit hole 489 of rear barrel 480.

[0131] 43(B), when the front end portion of clip 490 is lifted to grip an article, clip 490 rotates around inflection portion 495 or the vicinity of inflection portion 495. In other words, leaf spring 491 or clip main body 496 is configured so that clip 490 opens around inflection portion 495 or the vicinity of inflection portion 495. Leaf spring 491 or rear shaft 480 is configured so that clip 490 does not open beyond a predetermined opening angle. In other words, when an attempt is made to open clip 490 beyond the predetermined opening angle, as indicated by the symbol P in the figure, abutment portion 498 of clip main body 496 abuts against the side surface of barrel 402, i.e., rear shaft 480, and rotation of clip 490 is restricted. This prevents damage or plastic deformation of the leaf spring 491, and prevents damage to the press-fit hole 489 of the rear axle 480 by the first end 492 of the leaf spring 491 or damage to the receiving hole 496b of the clip body 496 by the second end 493 of the leaf spring 491.

[0132] 43(A), because curved portion 494 of clip 490 has concave inflection portion 495, clip 490 can be positioned closer to the central axis of barrel 402 by distance L from the diameter corresponding to the radius of curvature of curved portion 494. Therefore, clip 490 having leaf spring 491 with a larger radius of curvature so as to have a wider elastic range can be attached to barrel 402 closer to barrel 402 so as to minimize the attachment height. In other words, clip 490 having leaf spring 491 can provide a clip 490 for a writing instrument that ensures a wide elastic range, and a writing instrument 400 that includes the clip.

[0133] In particular, because writing instrument 400 is a multi-core writing instrument, the outer diameter of the barrel is larger than that of a writing instrument having only one refill. Using clip 490 described above, the entire multi-core writing instrument 400 having clip 490 can be made more compact. Furthermore, first knock member 405, which is disposed at the rear end of first refill 403 so as to protrude rearward from barrel 402, is disposed eccentrically with respect to the central axis of barrel 402. Specifically, first knock member 405 is disposed eccentrically with respect to the central axis of barrel 402 so as to be spaced apart from clip 490. This ensures that there is sufficient space for movement and contact of abutment portion 498 at the rear end of barrel 402 when clip 490 is opened, without being obstructed by first knock member 405.

[0134] The outer shape of curved portion 494 does not have to be formed with the same radius of curvature, and may be formed by combining straight lines and / or curves with multiple radii of curvature. The curve of curved portion 494 also includes a shape formed by bending a plate-like elastic material. Inflection portion 495 includes not only an inflection point in the mathematical sense, but also all concave shapes that protrude inward in approximately U-shaped leaf spring 491. Therefore, inflection portion 495 includes not only a curve but also a shape formed by bending a plate-like elastic material. [Explanation of symbols]

[0135] 400 Writing instruments 402 Shaft cylinder 403 1st Refill 404a 2nd refill 404b 2nd refill 405 First knock member 407 front axle 408 Knock Button 410 Stretching mechanism 416 Spring 420 outer cam 421 Rotating cam receiver 422 Locking cam surface 423 Outer cam protrusion 424 4th Slope 430 Extension Cam 431 Cam body 433 Rotating cam part 434 First Slope 435 Push-out cam part 436 Second Slope 440 Knock Cam 441 1st protrusion 442 Push-out cam receiving part 443 Third Slope 444 2nd protrusion 445 Cam surface 450 rotor 451 Small diameter section 452 Large diameter section 453 Inner Cam 454 Inner cam protrusion 460a Second knock member 460b Second knock member 470 Inner cylinder 480 rear axle

Claims

[Claim 1] The invention described in the specification.

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