JP7518876B2 - Knock-type writing instrument - Google Patents

Description

The present invention relates to a knock-type writing instrument.

A knock-type writing instrument is known that has a cylindrical knock lock member that can move back and forth inside the barrel due to gravity (Patent Document 1). With the knock-type writing instrument described in Patent Document 1, when the front end is facing upward, the knock lock member is locked, preventing the operating part located at the rear end of the barrel from moving forward, and knocking is not possible. Therefore, when erasing handwriting with the knock-type writing instrument using the erasing member provided at the rear end of the operating part, a stable rubbing operation can be performed. In other words, even if the knock-type writing instrument is changed and the erasing member is pressed against the writing surface to perform the rubbing operation, the erasing member does not rattle.

JP 2016-107615 A

In the knock-type writing instrument described in Patent Document 1, the cylindrical knock lock member moves in the front-rear direction near the inner circumferential surface of the barrel by gravity over a certain distance, so there are restrictions on the shape of the internal mechanism's parts and the location of the parts. In order to broaden the scope of the internal mechanism's design, it is preferable to realize, with other mechanisms, the prevention of forward movement of the operating part when the front end is facing upward.

The present invention aims to provide a knock-type writing instrument with a simple mechanism that enables stable rubbing and other actions.

According to one aspect of the present invention, there is provided a knock-type writing instrument that includes a barrel and an operating part, and that can be switched between a writing state and a non-writing state by performing a knock operation that presses the operating part forward, and further includes a brake member that can move back and forth within the barrel by gravity, a rotating member that moves together with the operating part and can rotate around a central axis, and a locking part that can be locked with the rotating member, and when the front end of the barrel is turned upward, the brake member moves rearward, and the rotation of the rotating member is restricted and the rotating member locks with the locking part, thereby preventing the operating part from moving forward.

The rotating member may be a cylindrical member. A protrusion may be provided on the inner surface of the rotating member, and the brake member inserted into the rotating member may engage with the protrusion to restrict the rotation of the rotating member. The rotating member may have a first inclined surface inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction, and the locking portion may have a second inclined surface inclined in the circumferential direction with respect to a plane perpendicular to the front-rear direction, and the first inclined surface of the rotating member whose rotation is restricted may come into contact with the second inclined surface of the locking portion to prevent the forward movement of the operating portion. The first inclined surface or the second inclined surface may have an inclination angle of more than 45 degrees with respect to the axial direction of the knock-type writing instrument. The writing instrument may include a plurality of writing bodies, a sliding member to which each of the writing bodies is connected, and a first cam surface disposed in front of the sliding member and cooperating with each of the sliding members, and at least one of the sliding members and the first cam surface may be separated in a writing state. All or part of the operating section may be an erasing section capable of erasing handwriting made by the knock-type writing instrument.

The aspects of the present invention have the common effect of providing a knock-type writing instrument with a simple mechanism that enables stable rubbing action, etc.

1 is a perspective view of a writing instrument according to an embodiment of the present invention. FIG. 2 is a longitudinal cross-sectional view of the writing instrument in a non-writing state with the front end pointing downwards. FIG. 2 is a vertical cross-sectional view of the writing implement in a writing position with the front end facing downwards. FIG. 2 is an enlarged vertical cross-sectional view of the writing implement with its front end facing upwards. FIG. 2 is a partial cross-sectional perspective view of the rear portion of the writing instrument. FIG. 2 is a perspective view of the rear of the writing instrument in a non-writing state. FIG. 7 is an opposite side perspective view of the writing instrument of FIG. 6 . FIG. FIG. FIG. FIG. FIG. FIG. FIG. FIG. FIG. FIG. 5A to 5C are schematic diagrams illustrating the operation of a knock ring. 5A to 5C are cross-sectional views illustrating the operation of the brake rod. 13 is another schematic diagram illustrating the operation of the knock ring. FIG. 13 is another schematic diagram illustrating the operation of the knock ring. FIG. 11A and 11B are schematic diagrams illustrating the operation of the refill when a knock operation is performed. 13A to 13C are schematic diagrams illustrating a switching operation of a retractable refill. 13A and 13B are schematic diagrams illustrating the operation of the refill when a knock operation is performed in another embodiment. FIG. 2 is a perspective view of a writing instrument according to another embodiment of the present invention. FIG. FIG. 11A and 11B are schematic diagrams illustrating the operation of the refill when a knock operation is performed.

The following describes in detail an embodiment of the present invention with reference to the drawings. Corresponding components are designated by the same reference symbols throughout the drawings.

1 is a perspective view of a writing instrument 1 according to an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of the writing instrument 1 in a non-writing state with the front end facing downward, FIG. 3 is a vertical cross-sectional view of the writing instrument 1 in a writing state with the front end facing downward, FIG. 4 is an enlarged vertical cross-sectional view of the writing instrument 1 with the front end facing upward, FIG. 5 is a partial cross-sectional perspective view of the rear of the writing instrument 1, FIG. 6 is a perspective view of the rear of the writing instrument 1 in a non-writing state, and FIG. 7 is a perspective view of the opposite side of the writing instrument 1 in FIG. 6.

The writing instrument 1 has a barrel 4 formed in a cylindrical shape and equipped with a front barrel 2 and a rear barrel 3, and a number of refills 5, which are writing bodies arranged inside the barrel 4 and equipped with a writing portion 5a at one end. The front barrel 2 and the rear barrel 3 may be integrally formed. Note that the rear barrel 3 is omitted in Figs. 6 and 7.

In this specification, in the axial direction of the writing instrument 1, the side of the writing part 5a is defined as the "front" side, and the side opposite the writing part 5a is defined as the "rear" side. Unless otherwise specified, the central axis or axial direction refers to the central axis or axial direction of the writing instrument 1.

The writing instrument 1 is a knock-type writing instrument in which the refill 5 is inserted and retracted from the barrel 4 by a knock operation that presses the operating part forward. The writing instrument 1 is also a multi-core writing instrument that has multiple refills 5.

The writing instrument 1 has an inner tube 20 attached to the rear end of the rear barrel 3 and equipped with a clip 28. The inner tube 20 may also be referred to as the barrel 4. Inside the barrel 4, the writing instrument 1 has a spacer 30, a collar member 40 arranged around the spacer 30, a rotating cam 50 arranged behind the collar member 40, sliding pieces 60 which are multiple sliding members arranged between the inner tube 20 and the collar member 40, an operating member 70 arranged behind the spacer 30, a rotor 80 arranged around the operating member 70, a brake rod 90 arranged inside the operating member 70, and a knock ring 100 arranged around the operating member 70 behind the rotor 80.

The eraser 7 is attached to the rear end of the operating member 70 via the holding member 6. The cover member 8 is detachably attached to the holding member 6, and the eraser 7 is covered by the cover member 8. The eraser 7 is integrally provided to the holding member 6 by adhesion or two-color molding. The eraser 7 may be detachable from the holding member 6, or a part of the holding member 6 may function as the eraser. The operating member 70 moves forward by pressing the cover member 8 in the attached state, or the eraser 7 in the removed state, forward, and a knock operation is performed. In other words, the rear end of the writing instrument 1, i.e., the eraser 7 or the cover member 8, functions as an operating part for the knock operation. Note that all or a part of the operating part may be an eraser part capable of erasing handwriting of the writing instrument 1. The cover member 8 is omitted in FIG. 4 and FIG. 5.

The retaining member 6 is biased rearward by the rear spring 10. Therefore, whether the writing instrument 1 is in a writing or non-writing state, the retaining member 6, erasing member 7, and cover member 8 are always positioned in the same axial position. The rear spring 10 may be omitted. A front spring 11 is disposed in front of the collar member 40, and the collar member 40 is biased rearward by the front spring 11. An annular display member 12 is disposed between the front shaft 2 and the rear shaft 3. Two triangular marks pointing in opposite directions in the circumferential direction are provided on the outer surface of the display member 12.

In Figs. 2 to 4, up is vertically up, and down is vertically down. That is, gravity acts downward in each figure. The brake rod 90 can move in the front-to-rear direction within the barrel 4 by gravity, as described below. Therefore, in Figs. 2 and 3, the front end of the writing instrument 1, i.e., the front end of the barrel 4, faces downward, so the brake rod 90 is closer to the front end within the barrel 4. On the other hand, in Fig. 4, the front end of the writing instrument 1 faces upward, so the brake rod 90 is closer to the rear end within the barrel 4 compared to Figs. 2 and 3.

The configuration of the main components will be explained with reference to Figures 1 to 7 as appropriate.

Figure 8 is a vertical cross-sectional view of the rear barrel 3. When the writing instrument 1 is assembled, the rear barrel 3 is positioned so that the upper side in Figure 8 is the rear side of the writing instrument 1. The inner peripheral surface of the rear barrel 3 is provided with two T-shaped protrusions 13 that are approximately T-shaped as locking portions. The two T-shaped protrusions 13 are arranged 120 degrees apart around the central axis. The inner peripheral surface of the front end of the rear barrel 3 is formed with a plurality of annular grooves 14 that are spaced apart in the axial direction. Note that the T-shaped protrusions 13 may not be provided on the inner peripheral surface of the rear barrel 3, but may be provided as separate members, for example.

Figure 9 is a vertical cross-sectional view of the inner tube 20. In the assembled state of the writing instrument 1, the inner tube 20 is arranged so that the upper side in Figure 9 is the rear side of the writing instrument 1. The inner tube 20 is attached to the rear end of the rear barrel 3 by fitting or press-fitting. A step portion 21 facing rearward is formed on the inner peripheral surface of the inner tube 20. Six first inner protrusions 22 extending in the axial direction are provided at equal intervals along the circumferential direction on the inner peripheral surface of the inner tube 20 forward of the step portion 21. A slope 22a inclined in the circumferential direction is formed on the front end surface of each of the first inner protrusions 22. The six first inner protrusions 22 constitute a first outer cam 23. A second inner protrusion 24 protruding further than the first inner protrusion 22 is formed as a locking portion on the rear end portion of each of the first inner protrusions 22. A circumferentially inclined slope 24a is formed on the rear end surface of each of the second inner protrusions 24, and a circumferentially inclined partial slope 24b (see FIG. 18(A) described later) is formed on a portion of the front end surface of each of the second inner protrusions 24. The six second inner protrusions 24 form a second outer cam 25. A rectangularly cut recess 26 is formed on the front end of the inner cylinder 20.

10 is a perspective view of the spacer 30. In the assembled state of the writing instrument 1, the spacer 30 is arranged so that the upper side in FIG. 10 is the rear side of the writing instrument 1. The spacer 30 has a cylindrical main body 31, three rail parts 32 extending rearward from the rear end of the main body 31, and a connecting part 33 formed to connect the rear ends of the three rail parts 32. The connecting part 33 has two connecting pieces 33a whose outer periphery is formed to be smaller than the outer diameter of the three rail parts 32, and one rotation restriction piece 33b formed as an extension of the rail part 32 or formed to be larger in diameter than the connecting piece 33a. The two adjacent rail parts 32 and the connecting part 33 define three grooves into which the refill 5 can be inserted. That is, in this embodiment, the writing instrument 1 can accommodate three refills 5. A flange part 34 is formed on the outer periphery of the main body 31, and the outer periphery of the main body 31 is divided into front and rear parts by the flange part 34. A protruding mark portion 35 that extends forward is formed on the front end surface of the flange portion 34. The mark portion 35 fits into a recess in the display member 12 (Figure 1). A male thread portion 36 is formed on the front portion of the main body portion 31, and the spacer 30 screws into the front shaft 2 by means of the male thread portion 36. A plurality of annular protrusions 37 spaced apart in the axial direction are formed on the rear portion of the main body portion 31.

Figure 11 is a perspective view of the collar member 40. When the writing instrument 1 is assembled, the collar member 40 is arranged so that the upper side in Figure 11 is the rear side of the writing instrument 1. The collar member 40 is formed in a cylindrical shape as a whole. Two T-shaped recesses 41 are formed on the outer circumferential surface of the collar member 40 at positions corresponding to the T-shaped protrusions 13 of the rear barrel 3 and with complementary shapes. A stepped raised portion 42 is formed on the portion of the rear end surface corresponding to the portion between the two T-shaped recesses 41. A cutout portion 43 is formed in a portion of the rear end surface of the collar member 40, which is cut obliquely from the rear end side toward the front (Figure 7). The rear end surface of the collar member 40, including the end face of the cutout portion 43, constitutes the first cam surface 44.

12 is a rear view of the rotating cam 50. In the assembled state of the writing instrument 1, the rotating cam 50 is arranged so that the upper side in FIG. 12 is the rear side of the writing instrument 1. The rotating cam 50 has an annular portion 51 formed in an annular shape around the central axis and a claw-shaped claw portion 52. The annular portion 51 is formed so as to be attached to the inner surface of the rear end portion of the claw portion 52. A protruding guide protrusion 53 is formed on the inner surface of the claw portion 52 so as to extend forward from the front end surface of the annular portion 51. As shown in FIG. 7, the outer shape of the rear portion of the claw portion 52 is formed in a rectangle complementary to the recess 26 of the inner tube 20. Therefore, in the writing instrument 1 in the non-writing state, the claw portion 52 fits into the recess 26 of the inner tube 20, and the outer surface of the rotating cam 50 is flush with the outer peripheral surface of the inner tube 20. In addition, the outer diameter of the annular portion 51 is formed slightly smaller than the inner diameter of the inner tube 20. The front of the claw portion 52 has a flat surface 54 that is formed flat and an end surface 55 that is formed at an angle. The flat surface 54 and the end surface 55 of the claw portion 52, together with the front end surface 27 of the inner cylinder 20 (Figure 9), form a second cam surface 56.

Figure 13 is a perspective view of the sliding top 60. When the writing instrument 1 is assembled, the sliding top 60 is positioned so that the upper side in Figure 13 is the rear side of the writing instrument 1. The sliding top 60 has an insertion section 61 that is inserted into the rear end of the refill 5, and a slider 62 formed on the side of the insertion section 61. The slider 62 slides along the first cam surface 44 as described below, so a small protrusion 63 is formed on the front end surface of the slider 62 to reduce frictional resistance during sliding. The slider 62 slides along the second cam surface 56, so a similar small protrusion may be formed on the rear end surface of the slider 62.

14 is a perspective view of the operating member 70. In the assembled state of the writing instrument 1, the operating member 70 is arranged so that the upper side in FIG. 14 is the rear side of the writing instrument 1. The operating member 70 is a hollow member with an open front end and a closed rear end. A cam flange 71 is formed on the outer peripheral surface of the operating member 70. A rotating cam surface 72 consisting of symmetrical and continuous peaks and valleys is formed on the front end surface of the cam flange 71. Six guide grooves 73 extending in the axial direction are formed at equal intervals along the circumferential direction on the outer peripheral surface of the cam flange 71. Two rectangular through holes 74 extending in the axial direction are formed on the outer peripheral surface of the operating member 70 behind the cam flange 71, which are spaced 180 degrees apart around the central axis. On the outer peripheral surface of the operating member 70, a step portion 75 facing rearward is formed behind the through hole 74, and a fitting protrusion 76 is formed behind the step portion 75. When the holding member 6 is attached to the rear end of the operating member 70, the fitting protrusion 76 fits into an opening provided in the holding member 6.

Figure 15 is a perspective view of the rotor 80. When the writing instrument 1 is assembled, the rotor 80 is arranged so that the upper side in Figure 15 is the rear side of the writing instrument 1. The rotor 80 is a cylindrical member. A rotating cam receiving surface 81 is formed on the rear end surface of the rotor 80, which is formed complementary to the rotating cam surface 72 of the operating member 70. The rotating cam receiving surface 81 cooperates with the rotating cam surface 72 of the operating member 70. Six protrusions 82 are formed on the outer peripheral surface of the rotor 80, which extend in the axial direction and are equally spaced along the circumferential direction, and the rear end surfaces of the protrusions 82 constitute a first inner cam 83. Six locking grooves 84 extending in the front-rear direction are defined by two adjacent protrusions 82. A locking portion 85 is formed on the rear end surface of each of the protrusions 82.

Figure 16 is a perspective view of the brake rod 90. When the writing instrument 1 is assembled, the brake rod 90 is arranged so that the upper side in Figure 16 is the rear side of the writing instrument 1. The brake rod 90 is a solid member. A small diameter section 91 is formed at the rear end of the brake rod 90, and a large diameter section 92 with a larger diameter is formed in front of the small diameter section 91. The small diameter section 91 and the large diameter section 92 are connected by a tapered surface 93. Two rectangular projections 94 are formed on the outer circumferential surface of the large diameter section 92, which extend in the axial direction and are spaced 180 degrees apart around the central axis, and a rectangular cutout is made in a portion of the rear of the projections 94 to define a restricting section 95.

Figure 17 is a perspective view of the knock ring 100. In the assembled state of the writing instrument 1, the knock ring 100 is arranged so that the upper side in Figure 17 is the rear side of the writing instrument 1. The knock ring 100 is a cylindrical member. On the inner peripheral surface of the knock ring 100, two restricting protrusions 101 are formed, which extend in the axial direction and are spaced apart by 180 degrees around the central axis. On the outer peripheral surface of the front end of the knock ring 100, four first outer protrusions 102 in the shape of a right triangle are formed. The two first outer protrusions 102 are arranged at a distance of 60 degrees around the central axis, and the other two corresponding first outer protrusions 102 are arranged at a distance of 180 degrees around the central axis. Behind each of the first outer protrusions 102, a second outer protrusion 103 in the shape of a parallelogram is formed. The first outer protrusions 102 and the second outer protrusions 103 constitute a second inner cam 104.

Next, the combination and arrangement of each part in the writing instrument 1 will be explained with reference to Figures 1 to 7.

The spacer 30 is screwed to the front axle 2 by the male threaded portion 36. The front end of the rear axle 3 is inserted into the rear of the main body 31 of the spacer 30. At this time, each of the annular protrusions 37 of the spacer 30 fits into the corresponding annular groove 14 of the rear axle 3, so that the rear axle 3 is rotatably connected to the spacer 30 and thus to the front axle 2 without easily coming off. The front spring 11 and the collar member 40 are arranged around the rail portion 32 of the spacer 30. The front end of the front spring 11 is supported by the rear end surface of the main body 31 of the spacer 30, and the rear end of the front spring 11 abuts against the front end surface of the collar member 40. The collar member 40 is movable in the front-rear direction and is biased rearward by the front spring 11. Each of the T-shaped protrusions 13 of the rear axle 3 is accommodated in the corresponding T-shaped recess 41 of the collar member 40, so that the rotation of the collar member 40 around the central axis is restricted. Therefore, when the rear axle 3 is rotated relative to the front axle 2, the collar member 40 rotates together with the rear axle 3.

The refills 5 and the sliding pieces 60 are connected by inserting the insertion portion 61 of the sliding piece 60 into the rear end of each of the three refills 5. In this state, each of the refills 5 is inserted into the groove between the rail portions 32 of the spacer 30 and can move in the front-rear direction. At this time, the slider 62 of the sliding piece 60 protrudes radially outward from the rail portion 32 of the spacer 30. The slider 62 engages with the edge of the rail portion 32, preventing the refills 5 from falling off between the rail portions 32. The slider 62, particularly the small protrusion 63 of the slider 62, abuts against the first cam surface 44 of the collar member 40. At this time, one of the sliders 62 of the three sliding pieces 60 is disposed on the first cam surface 44 of the cutout portion 43 of the collar member 40, and the remaining sliders 62 are disposed on the first cam surface 44 of the rear end surface of the collar member 40.

Since the collar member 40 is biased backward by the front spring 11, each of the sliding pieces 60 is also biased backward via the collar member 40, and furthermore, the rotating cam 50 is biased backward via the sliding pieces 60. The rearward movement of the collar member 40, and therefore the sliding pieces 60, is restricted by the rear end surface of the slider 62 abutting against the second cam surface 56 of the rotating cam 50, which includes the front end surface 27 of the inner tube 20. Therefore, each of the sliders 62 of the sliding pieces 60 is disposed between the first cam surface 44 and the second cam surface 56. The claw portion 52 of the rotating cam 50 can move in the front-rear direction within the recess 26 of the inner tube 20. At this time, the annular portion 51 of the rotating cam 50 slides along the inner peripheral surface of the inner tube 20.

The operating member 70 is disposed within the barrel 4 so that each of the first inner protrusions 22 of the inner barrel 20 is disposed in the corresponding guide groove 73. This allows the operating member 70 to move in the front-rear direction within the barrel 4 without rotating during the knock operation. The front end of the rear spring 10 is supported by the step 21 of the inner barrel 20, and the rear end of the rear spring 10 abuts against the retaining member 6. As a result, the rear spring 10 biases the retaining member 6, and in turn the operating member 70 to which the retaining member 6 is attached, rearward. The rearward movement of the operating member 70 is restricted by the rear end surface of the cam flange 71 abutting against the front end surface of the second inner protrusion 24 of the inner barrel 20.

The rotor 80 is arranged on the outer peripheral surface of the operating member 70 in front of the cam flange 71 so as to be movable in the front-rear direction and rotatable. At this time, the first inner cam 83 of the rotor 80 is arranged to cooperate with the first outer cam 23 of the inner cylinder 20. In the writing instrument 1 in the non-writing state (FIG. 2), the front end of the rotor 80 is inserted into the annular portion 51 of the rotating cam 50, and the front end surface of the protrusion 82 of the rotor 80 abuts against the rear end surface of the annular portion 51 of the rotating cam 50. At this time, the rear end surface of the rotor 80, i.e., the rotating cam receiving surface 81, abuts against the rotating cam surface 72 of the operating member 70. As described above, the rotating cam 50 is urged backward by the front spring 11 via the sliding top 60, so that the rotor 80, and therefore the operating member 70 abutting thereon, are also urged backward.

The brake rod 90 is disposed inside the operating member 70, and thus the rotor 80. The brake rod 90 can move in the front-rear direction inside the operating member 70 by gravity. The forward movement of the brake rod 90 is restricted by abutment with the rear end face of the spacer 30, i.e., the rear end face of the connecting portion 33. The rearward movement of the brake rod 90 is restricted by the tapered surface 93 of the brake rod 90 engaging with the inner surface of the operating member 70 (Figure 4).

A knock ring 100 is rotatably arranged around the through hole 74 of the operating member 70, and the knock ring 100 can move in the front-rear direction together with the operating member 70. Specifically, the knock ring 100 is arranged between the cam flange 71 of the operating member 70 and the holding member 6 attached to the operating member 70, and the movement in the front-rear direction relative to the operating member 70 is restricted. At this time, as described later with reference to FIG. 19, each of the restricting protrusions 101 of the knock ring 100 is arranged in the corresponding through hole 74 of the operating member 70, so that the knock ring 100 can rotate within a predetermined angle range in the through hole 74. Furthermore, the second inner cam 104 of the knock ring 100 is arranged to cooperate with the second outer cam 25 of the inner cylinder 20.

Next, the operation of the writing instrument 1 will be described.

The writing instrument 1 is switched between the writing state and the non-writing state by performing a knock operation that presses the operating part at the rear end of the writing instrument 1 forward against the biasing force of the rear spring 10 and the front spring 11, and the basic operation will be explained below. Switching between the writing state and the non-writing state is performed by cooperation between the rotating cam surface 72 of the operating member 70 and the rotating cam receiving surface 81 of the rotor 80, and by cooperation between the first inner cam 83 of the rotor 80 and the first outer cam 23 of the inner tube 20. The cooperation between these cams is the same as that of conventional knock-type writing instruments, so it will be explained briefly below.

In the non-writing state, each of the protrusions 82 of the rotor 80 is disposed between the first inner protrusions 22 of the inner tube 20, thereby restricting the rotation of the rotor 80. In other words, the first inner protrusions 22 of the inner tube 20 are disposed within the locking grooves 84 of the rotor 80. Therefore, the rotation of the rotor 80 is restricted. At this time, the rotating cam surface 72 of the operating member 70 and the rotating cam receiving surface 81 of the rotor 80 are in contact with each other, but are out of phase with each other.

When the operating member 70 moves forward by the knock operation, it is pressed against the cam flange 71, causing the rotor 80 to move forward. When the rotor 80 moves forward, it is pressed against the claw portion 52, causing the sliding top 60 with the slider 62 arranged in the cutout portion 43 of the collar member 40, and further the collar member 40, to move forward. As a result, the refill 5 connected to this sliding top 60 protrudes from the barrel 4.

When the rotor 80 moves forward and the rear end of the projection 82 passes the front end of the first inner projection 22 of the inner cylinder 20 in the front-rear direction, the restriction on the rotation of the rotor 80 is released. At that moment, a circumferential component force acts to return the misaligned phase between the rotating cam surface 72 of the operating member 70 and the rotating cam receiving surface 81 of the rotor 80 to the original position, and this component force rotates the rotor 80 slightly.

Next, when the knock operation is stopped, the sliding top 60, the rotating cam 50, the rotor 80 and the operating member 70 move slightly backwards through the collar member 40 due to the biasing force of the front spring 11. At this time, the first inner cam 83 of the rotor 80 and the first outer cam 23 of the inner cylinder 20 cooperate to further rotate the rotor 80. That is, the inclined surface 22a of the first inner protrusion 22 of the inner cylinder 20 and the rear end surface of the protrusion 82 of the rotor 80, which are inclined surfaces inclined in the same direction, come into contact with each other, and a circumferential component force acts, which further rotates the rotor 80 slightly. This rotation causes the phase of the rotating cam surface 72 of the operating member 70 and the rotating cam receiving surface 81 of the rotor 80 to shift again. The rotation and backward movement of the rotor 80 are restricted by the first inner protrusion 22 of the inner cylinder 20 engaging with the engaging portion 85 of the rotor 80. As a result, the refill 5 remains protruding from the barrel 4, and the writing instrument 1 is in a writing state.

To switch from the writing state to the non-writing state, a knock operation is performed again. When the operating member 70 moves forward by the knock operation, it is pressed against the cam flange 71 and the rotor 80 moves forward. When the rotor 80 moves forward and the rear end of the protrusion 82 passes the front end of the first inner protrusion 22 of the inner cylinder 20 in the front-rear direction, the restriction on the rotation of the rotor 80 is released. At that moment, a circumferential component force acts to return the misaligned phase between the rotating cam surface 72 of the operating member 70 and the rotating cam receiving surface 81 of the rotor 80 to its original position, and this component force rotates the rotor 80 slightly.

Next, when the knock operation is stopped, the sliding top 60, the rotating cam 50, the rotor 80 and the operating member 70 move slightly backwards via the collar member 40 due to the biasing force of the front spring 11. At this time, the first inner cam 83 of the rotor 80 and the first outer cam 23 of the inner cylinder 20 cooperate to further rotate the rotor 80. That is, the inclined surface 22a of the first inner protrusion 22 of the inner cylinder 20 and the rear end surface of the protrusion 82 of the rotor 80, which are inclined surfaces inclined in the same direction, come into contact with each other, and a circumferential component force acts, which further rotates the rotor 80 slightly. This rotation causes the phase of the rotating cam surface 72 of the operating member 70 and the rotating cam receiving surface 81 of the rotor 80 to shift again. The rotation of the rotor 80 is restricted by each of the protrusions 82 of the rotor 80 being again positioned between the first inner protrusions 22 of the inner cylinder 20. The rearward movement of the rotor 80 is restricted by the cam flange 71 of the operating member 70. The rearward movement of the rotor 80 causes the collar member 40, the sliding top 60, and the rotating cam 50, which are biased by the front spring 11, to move rearward as well. As a result, the refill 5 is retracted into the barrel 4, and the writing instrument 1 is in a non-writing state.

The knock operation for switching between the writing state and the non-writing state described above is performed with the front end of the writing instrument 1 facing downward. On the other hand, if the front end of the writing instrument 1 faces upward, the knock operation cannot be performed. In other words, even if an attempt is made to press the operating part forward, the movement of the operating member 70 is prevented, and the operating member 70 cannot be moved forward. This will be described below.

Figure 18 is a schematic diagram explaining the operation of the knock ring 100. Figure 18 shows the positional relationship of the second inner cam 104 of the knock ring 100, that is, the positional relationship between the second inner protrusion 24 of the inner cylinder 20 and the first outer protrusion 102 and the second outer protrusion 103 of the knock ring 100, with respect to the second outer cam 25 developed in the circumferential direction. In Figure 18, 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. Figure 18 (A) shows the state before the knock operation is performed, Figure 18 (B) shows the state immediately after the operating part starts to move forward by the knock operation, Figure 18 (C) shows the state in which the operating part has moved forward by the knock operation, and Figure 18 (D) shows the state immediately before the operating part returns to its original position by stopping the knock operation.

Referring to FIG. 18(A), before the knock operation, the second inner protrusion 24 of the inner cylinder 20 is disposed in front of the second outer protrusion 103 of the knock ring 100. When the knock operation is performed from this state, the operating member 70 moves forward relative to the inner cylinder 20, and therefore the knock ring 100 also moves forward. At this time, the second outer cam 25 of the inner cylinder 20 and the second inner cam 104 of the knock ring 100 cooperate to rotate the knock ring 100. That is, the inclined surface 24a of the second inner protrusion 24 of the inner cylinder 20 and the front end surface of the second outer protrusion 103 of the knock ring 100, which have inclined surfaces inclined in the same direction, come into contact with each other, and a circumferential component force acts, causing the knock ring 100 to rotate while advancing (FIG. 18(B)). When the operating member 70 moves further forward, the second inner protrusion 24 of the inner cylinder 20 passes next to the second outer protrusion 103, allowing the knock ring 100, and therefore the operating member 70, to move sufficiently forward (FIG. 18(C)), and the knock operation is performed.

When the knock operation is stopped from the state shown in FIG. 18(C), the force of the rear spring 10 causes the operating member 70 to move backward relative to the inner tube 20, and therefore the knock ring 100 also moves backward. At this time, the second outer cam 25 of the inner tube 20 and the second inner cam 104 of the knock ring 100 cooperate to rotate the knock ring 100 in the opposite direction. That is, the partial inclined surface 24b of the second inner protrusion 24 of the inner tube 20 and the rear end surface of the first outer protrusion 102 of the knock ring 100, which have inclined surfaces in the same direction, come into contact with each other, and a component force in the circumferential direction acts, causing the knock ring 100 to rotate while retreating (FIG. 18(D)). As a result, the knock ring 100, and therefore the operating member 70, return to their original positions (FIG. 18(A)).

As described above, when the front end of the writing instrument 1 faces downward, the knock ring 100 rotates in response to the knock operation, making it possible to perform the knock operation without preventing the forward movement of the operating member 70, i.e., the operating part. On the other hand, when the front end of the writing instrument 1 faces upward, the brake rod 90 restricts the rotation of the knock ring 100, preventing the operating part from moving forward, and making it impossible to perform the knock operation. This knock lock mechanism will be described with reference to FIG. 19.

Figure 19 is a cross-sectional view explaining the operation of the brake rod 90. Figure 19(A) is a cross-sectional view taken along line A-A in Figure 3, in which the front end of the writing instrument 1 faces downward, and Figure 19(B) is a cross-sectional view taken along line B-B in Figure 4, in which the front end of the writing instrument 1 faces upward.

As shown in FIG. 19(A), when the front end of the writing instrument 1 faces downward, the restricting protrusions 101 of the knock ring 100 are disposed within the through holes 74 of the operating member 70. As in FIG. 18(A), FIG. 19(A) shows the state before the knock operation is performed, and at this time, the restricting protrusions 101 are close to one edge of the through hole 74. Therefore, the knock ring 100 can rotate within a predetermined angle range within the range of restriction that the restricting protrusions 101 receive from the edge of the through hole 74.

As shown in FIG. 19(B), when the front end of the writing instrument 1 faces upward, the restricting protrusions 101 of the knock ring 100 are disposed in the through holes 74 of the operating member 70, and the restricting portions 95 are disposed to fill the gaps of the through holes 74. In other words, when the front end of the writing instrument 1 faces upward, the brake rod 90 moves rearward due to gravity. This causes the brake rod 90 to be inserted further inside the operating member 70, and the restricting portions 95 are inserted into the gaps of the through holes 74. As a result, the restricting protrusions 101 of the knock ring 100 engage with the restricting portions 95 of the brake rod 90, restricting the rotation of the knock ring 100.

As explained with reference to FIG. 18(B), if the knock ring 100 cannot rotate, even if the inclined surface 24a of the second inner protrusion 24 of the inner tube 20 comes into contact with the front end surface of the second outer protrusion 103 of the knock ring 100, the knock ring 100 will not rotate. As a result, the second inner protrusion 24 of the inner tube 20 and the second outer protrusion 103 of the knock ring 100 engage with each other, preventing further forward movement of the operating member 70. Therefore, when the front end of the writing instrument 1 is facing upward, forward movement of the operating part is prevented, and the knock operation cannot be performed.

When the front end of the writing instrument 1 is changed from an upward to a downward position, the brake rod 90 moves forward, and the restriction on the rotation of the knock ring 100 is released. As a result, the knock operation can be performed again.

When the front end of the writing instrument 1 is facing upward, the operating part is prevented from moving forward, so that, for example, when erasing handwriting with the writing instrument 1 using the erasing member 7, a stable rubbing action can be performed. In other words, even if the writing instrument 1 is changed in grip and the operating part is pressed against the writing surface to perform a rubbing action, the operating part does not rattle. With the writing instrument 1, a stable rubbing action can be achieved with a mechanism that is simpler than conventional mechanisms.

For example, the conventional knock lock mechanism described in Patent Document 1 (JP Patent Publication 2016-107615) has a single knock lock member, and the knock lock member moves back and forth due to gravity and rotates to prevent the operation unit from moving forward. In contrast, the knock lock mechanism of the writing instrument 1 has a brake rod 90 and a knock ring 100. Therefore, the components responsible for movement and rotation are separated, with the brake rod 90 only moving due to gravity and the knock ring 100 only rotating. As a result, the knock lock mechanism of the writing instrument 1 can have a shorter overall length as a mechanism than the knock lock mechanism of Patent Document 1, and allows for greater freedom in designing the part shapes and part placement locations of the internal mechanism, such as near the inner circumferential surface of the barrel.

The brake rod may be a brake member of any shape so long as it can move back and forth inside the barrel due to gravity. The knock ring may be a C-shape that is not a perfect ring, and may be a rotating member of any shape so long as it moves with the operating part and can rotate around the central axis. The brake member and rotating member may be of any shape, so long as the brake member moves rearward when the front end of the barrel is turned upward, and the rotation of the rotating member is restricted and the rotating member engages with the locking part, preventing the operating part from moving forward.

However, if the writing instrument 1 is dropped by mistake while the front end of the writing instrument 1 is facing upward, a strong impact is applied to the operating part in the axial direction. At this time, the inclined surface 24a of the second inner protrusion 24 of the inner cylinder 20 collides with the front end surface of the second outer protrusion 103 of the knock ring 100, and the second inner protrusion 24 is deformed so as to bulge in the circumferential direction. In this case, the deformed second inner protrusion 24 cannot pass between the adjacent second outer protrusions 103 of the knock ring 100 as shown in FIG. 18(B), and there is a risk that the knock operation cannot be performed. In addition, even if the deformed second inner protrusion 24 can pass between the adjacent second outer protrusions 103 of the knock ring 100, the deformed second inner protrusion 24 may get caught between the second outer protrusions 103, and the operating part may not be able to return to its original position. This will be described with reference to FIG. 20.

Figure 20 is another schematic diagram explaining the operation of the knock ring 100. Figure 20 is a diagram similar to Figure 18, and in Figure 20, 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 the knock ring 100 shown in Figure 20, the second outer protrusion 103 corresponding to the second inner protrusion 24 passing between the adjacent second outer protrusions 103, i.e., the second outer protrusion 103 on the right side in the figure, is formed shorter in the axial direction. In other words, the front end surface of the second outer protrusion 103 on the right side in the figure is formed to be positioned rearward of the front end surface of the other second outer protrusion 103.

Figure 20 (A) shows the moment when the rear end surface of the second inner protrusion 24 of the inner tube 20, which does not pass between the adjacent second outer protrusions 103, collides with the front end surface of the second outer protrusion 103 of the corresponding knock ring 100 due to the drop of the writing instrument 1. At this time, the other second inner protrusion 24 of the inner tube 20 does not collide with the second outer protrusion 103 because the front end surface of the second outer protrusion 103 of the corresponding knock ring 100 is located further rearward. In Figure 20 (B), as a result of the collision, the second inner protrusion 24 of the inner tube 20, which does not pass between the adjacent second outer protrusions 103, has a deformed deformation portion 24c. At this time, the second inner protrusion 24 of the other inner tube 20 is not deformed, so it can pass between the adjacent second outer protrusions 103, and does not affect the knock operation.

However, during normal knocking operation, when the rear end surface of the second inner protrusion 24 of the inner cylinder 20 comes into contact with the front end surface of the second outer protrusion 103 of the knock ring 100, the second inner protrusion 24 of the inner cylinder 20 and the second outer protrusion 103 of the knock ring 100 may engage with each other, preventing the knock ring 100 from rotating. This will be explained with reference to Figure 21.

Figure 21 is another schematic diagram explaining the operation of the knock ring 100. Figure 21 is a diagram similar to Figure 18, and in Figure 21, 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 Figure 21, by setting the angle α of the acute angle portion of the front end of the second outer protrusion 103 of the knock ring 100, particularly the second outer protrusion 103 on the left side in the figure, in the range of 45 degrees to 90 degrees, unintended engagement between the second inner protrusion 24 of the inner tube 20 and the second outer protrusion 103 of the knock ring 100 can be prevented.

As described above, by performing a knock operation, the operating member 70, the rotor 80, and the rotating cam 50 move forward. When the rotating cam 50 moves forward, it is pressed by the claw portion 52, and the sliding top 60 having the slider 62 arranged in the cutout portion 43 of the collar member 40, and further the collar member 40, move forward. As a result, the writing part 5a of the refill 5 connected to this sliding top 60 protrudes from the barrel 4. The operation of protruding a specific refill 5 will be described with reference to FIG. 22.

Figure 22 is a schematic diagram explaining the operation of the refill during the knock operation. As described above, each of the sliders 62 of the sliding top 60 is disposed between the first cam surface 44 and the second cam surface 56, and since these are shown in FIG. 22 as being expanded in the circumferential direction, the left and right are connected in each figure. Each of the sliding tops 60 cooperates with the first cam surface 44 and the second cam surface 56. The circle mark on one of the three sliding tops 60 is a mark drawn for convenience in identifying the sliding top 60. In FIG. 22, 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. FIG. 22(A) shows the collar member 40, rotating cam 50, and sliding top 60 when the writing instrument 1 is not in a writing state, FIG. 22(B) shows the collar member 40, rotating cam 50, and sliding top 60 immediately after the start of a knock operation, and FIG. 22(C) shows the collar member 40, rotating cam 50, and sliding top 60 when the writing instrument 1 is in a writing state. In addition, FIG. 22 shows a schematic diagram of the T-shaped protrusion 13 provided on the inner peripheral surface of the rear barrel 3.

22(A), when the knock operation is performed from the state shown in FIG. 22(A), the rotating cam 50 also moves forward due to the forward movement of the operating member 70, and the sliding top 60 marked with a circle and the collar member 40 arranged in the notch 43 move forward. At this time, the remaining two sliding tops 60 engage with the T-shaped protrusion 13 provided on the inner peripheral surface of the rear barrel 3, which is relatively stationary (FIG. 22(B)). Therefore, it can be said that the first cam surface 44 includes the rear end surface of the T-shaped protrusion 13. Next, when the rotating cam 50 moves further, as described above, the first inner cam 83 of the rotor 80 and the first outer cam 23 of the inner barrel 20 cooperate, and the writing instrument 1 enters the writing state (FIG. 22(C)). At this time, the remaining two sliding tops 60 do not move forward because they are engaged with the T-shaped protrusion 13 provided on the inner peripheral surface of the rear barrel 3.

If the T-shaped protrusion 13 were not present, the other refills 5 other than the refill 5 protruding from the barrel 4 would also move forward due to gravity. This would result in multiple refills 5 gathering in the tapered portion at the front end of the front barrel 2, which could potentially impede the movement of the refill 5 that is to be protruded. Therefore, the writing instrument 1 is provided with a T-shaped protrusion 13, which allows the other refills 5 to engage with it, thereby restricting the unnecessary forward movement of the other refills 5. Therefore, the T-shaped protrusion 13 can be of any shape as long as it is capable of engaging the refill 5.

As is clear from FIG. 22, by knocking, the refill 5 connected to the sliding top 60 that is relatively advanced among the three refills 5 protrudes from the front end opening of the barrel 4, and the writing instrument 1 enters a writing state. Therefore, by positioning the writing part 5a of the refill 5 that is relatively advanced in the non-writing state of the writing instrument 1 in the vicinity of the front end opening of the barrel 4, the refill 5 can be protruded and placed in a writing state with a smaller knock operation amount, i.e., a smaller knock stroke. In addition, during the knock operation, the second cam surface 56 of the rotating cam 50 itself advances and presses the sliding top 60, so that rattling between the parts can be suppressed. In addition, the rotating cam 50, especially the claw portion 52, can be a relatively large part, and its strength can be increased.

Figure 23 is a schematic diagram explaining the switching operation of the retractable refill 5, i.e., the operation for changing the refill 5 to be used for writing. Figure 23 is a diagram similar to Figure 22, and in Figure 23, 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. The spacer 30 is fixed to the front shaft 2. Meanwhile, the inner tube 20, the collar member 40, the rotating cam 50, and the rear shaft 3 are rotatable relative to the front shaft 2, and constitute a rotation selection member. In other words, the front shaft 2 is rotatable relative to the rear shaft 3.

23, for convenience of explanation, the rotation of the rear axle 3 relative to the front axle 2 is based on the rear axle 3, so that only the sliding top 60 moves left and right in FIG. 23 in response to the rotation of the rear axle 3. In reality, the sliding top 60 only moves forward and backward in the groove between the rail portions 32 of the spacer 30. Also, for convenience of explanation, the three sliding tops 60 are distinguished as sliding tops 60A, sliding tops B, and sliding tops 60C. As described above, during the knock operation, the refill 5 connected to the sliding top 60 arranged in the cutout portion 43 of the collar member 40, i.e., the refill 5 arranged at the selected position, is pressed by the claw portion 52 and protrudes from the barrel 4. Therefore, by changing the refill 5 arranged at the selected position, the desired refill 5 can be made to appear and disappear. Furthermore, for convenience of explanation, the rear axle 3 is assumed to be freely rotatable relative to the front axle 2.

Figure 23 (A) shows the writing instrument 1 in a non-writing state with the sliding top 60A in a forward position. When a knock operation is performed in this state, the refill 5 connected to the sliding top 60A enters a writing state, as described above. At this time, the other sliding tops 60B and 60C engage with the T-shaped protrusion 13 provided on the inner surface of the rear barrel 3, as explained with reference to Figure 22, and are restricted from moving forward.

23(A), when the rear shaft 3 is rotated clockwise relative to the front shaft 2 as viewed from the rear of the writing instrument 1, each of the sliding tops 60 moves relatively to the right in the figure. At this time, as the rear shaft 3 rotates, i.e., the collar member 40 rotates, the sliding top 60A, which was positioned in a forward position, moves rearward along the slope of the first cam surface 44, and the sliding top 60B rides up onto the raised portion 42 against the biasing force of the front spring 11 (FIG. 23(B)). As the sliding top 60B rides up onto the raised portion 42, the collar member 40 has moved forward by the height of the raised portion 42 compared to the state shown in FIG. 23(A).

Furthermore, when the rear axle 3 is rotated, the sliding top 60B moves relatively circumferentially along the raised portion 42, and the sliding top 60C moves forward along the end face 55 of the rotating cam 50 (FIG. 23(C)). Next, at the moment when the sliding top 60B passes the end of the raised portion 42, the collar member 40, which has moved forward by the height of the raised portion 42, moves instantly backward due to the biasing force of the front spring 11 (FIG. 23(D)). At this time, the sliding top 60B collides with the rear end face of the collar member 40. At the same time, the sliding top 60C collides with the end face of the cutout portion 43 of the collar member 40. At the same time, the sliding top 60A collides with the front end face 27 of the inner tube 20. As a result, the sliding top 60C is placed in the cutout portion 43 of the collar member 40, and the switching of the refill 5 is completed (FIG. 23(E)). Because these collisions occur almost simultaneously, the user who was rotating the rear axle 3 can feel the impact and the clicking sound that results from the impact, and can recognize that the switching operation of the retractable refill 5 has been completed. The raised portion 42 may be omitted.

The torque required to start rotating the rear axle 3 to switch between retractable refills 5, i.e., the initial torque, can be changed to a desired value by changing the height of the stepped raised portion 42 or the shape of the stepped portion. By appropriately adjusting the initial torque, taking into account the frictional resistance associated with the movement of the sliding top 60, and applying a torque equal to or greater than the initial torque to rotate the refill, the subsequent inertial force can instantly switch to the adjacent refill 5.

Figure 24 is a schematic diagram illustrating the operation of the refill 5 during a knock operation in another embodiment. Figure 24 is a diagram similar to Figure 22, with the upper part being the rear side of the writing instrument 1 and the lower part being the front side of the writing instrument 1. In Figure 24, the axial length of the claw portion 152 of the rotating cam 150 is set so that the front end surface of the claw portion 152 is aligned with the front end surface 27 of the inner tube 20. In this case, the refill 5 at the selected position is not the refill 5 connected to the sliding top 60 at the forward position, i.e., the notch portion 43, but the refill 5 connected to the sliding top 60 at the position opposite the claw portion 152 of the rotating cam 150 in the axial direction. In this embodiment, the sliding top 60 and the rotating cam 150 do not come into contact with each other when the rear shaft 3 is rotated, so that the refill 5 that can be protruded and retracted can be switched more smoothly.

In the above-described embodiment, the rotation of the rear shaft 3 relative to the front shaft 2, i.e., the rotation of the rotation selection member, is restricted within a predetermined angle range. That is, as shown in FIG. 2, in the writing instrument 1 in the non-writing state, the front end of the guide protrusion 53 of the rotating cam 50 can be positioned outside the connecting piece 33a of the spacer 30. In other words, the connecting piece 33a of the spacer 30 and the guide protrusion 53 of the rotating cam 50 do not interfere with each other. In this state, when the rear shaft 3 is rotated in one direction relative to the front shaft 2, the rotation restriction piece 33b of the spacer 30 and the guide protrusion 53 of the rotating cam 50 abut against each other, and the rotation of the rear shaft 3 is restricted. That is, one side surface 33c (FIG. 10) in the circumferential direction of the rotation restriction piece 33b of the spacer 30 abuts against the guide protrusion 53 of the rotating cam 50. When the rear axle 3 is rotated in the other direction relative to the front axle 2, the other side surface 33c in the circumferential direction of the rotation restriction piece 33b of the spacer 30 comes into contact with the guide protrusion 53 of the rotating cam 50. Therefore, the rotation of the rotation selection member can be restricted to a predetermined angle range. At this time, for example, after the rear axle 3 is rotated 120 degrees from the state shown in FIG. 23(A) to the state shown in FIG. 23(E) in which the sliding top 60C is disposed in the notch 43 of the collar member 40, the rear axle 3 cannot be rotated any further. Therefore, in order to dispose the sliding top 60B in the notch 43 of the collar member 40, the rear axle 3 needs to be rotated 240 degrees in the opposite direction. Note that the rotation of the rotation selection member may be restricted to a predetermined angle range by providing a locking mechanism to the multiple annular protrusions 37 of the spacer 30 or the multiple annular grooves 14 of the rear axle 3.

By restricting the angle at which the rear shaft 3 can rotate to a predetermined range (i.e., a range of 240 degrees), it is possible to make it possible to distinguish at a glance which refill 5 will be projected by the knock operation at that time. That is, in the state shown in FIG. 23(A), as shown in FIG. 1, the clip 28 of the inner cylinder 20 and the mark portion 35 arranged on the display member 12 are configured to be aligned. When the clip 28 and the mark portion 35 are aligned, the refill 5 connected to the sliding piece 60A will be projected by the knock operation. Since the mark portion 35 moves integrally with the front shaft 2, the positional relationship between the clip 28 and the mark portion 35 changes depending on the rotation direction of the front shaft 2. Therefore, by looking at the positional relationship between the clip and the mark portion 35, it is possible to distinguish which refill 5 is in the selected position and will be in writing state by the knock operation. At this time, the mark portion 35 and the two triangular marks (FIG. 1) may be colored with the ink color of the refill 5 to make it easier to distinguish.

The front shaft 2 and the rear shaft 3 can rotate relatively only when the writing instrument 1 is in a non-writing state. In other words, the rotation selection member can be rotated only when the writing instrument 1 is in a non-writing state. That is, in the writing instrument 1 in a writing state, the rotating cam 50 moves forward as shown in FIG. 22 (C). At this time, the rotating cam 50 presses the corresponding sliding top 60 forward, and the guide protrusion 53 of the rotating cam 50 is inserted into the groove between the rail portion 32 of the spacer 30. Therefore, even if an attempt is made to rotate the rotation selection member, the rotation is restricted by the engagement between the guide protrusion 53 of the rotating cam 50 and the rail portion 32, and the rotation cannot be performed. Therefore, when the writing instrument 1 is in a writing state, the front shaft 2 cannot be rotated relative to the rear shaft 3. Therefore, a malfunction in which the rotation selection member is unintentionally rotated during writing and the refill 5 is changed is prevented. On the other hand, when the writing instrument 1 is not in a writing state, the guide protrusion 53 of the rotating cam 50 is positioned behind the rail portion 32 and is not engaged with the rail portion 32, allowing the rotation selection member to rotate.

Even if the writing instrument 1 is changed from the writing state to the non-writing state by a knock operation, the same refill 5 is in the selected position unless the rotating selection member is rotated as described with reference to FIG. 23. Therefore, for example, after writing in black, if the writing instrument 1 is changed to the non-writing state by a knock operation and then the writing instrument 1 is to be written in black again, the black refill 5 can be put into the writing state again by knocking a single operating unit without selecting an operating unit corresponding to each refill. In other words, the same refill 5 can be easily repeatedly inserted and removed by knocking a single operating unit without having to search for a specific operating unit each time to project the desired refill 5 from among multiple operating units. On the other hand, to switch the refill 5 that is in the writing state by a knock operation, it can be easily done by rotating the rotating selection member around the axis as described above.

In addition, by rotating the rotation selection member around the axis, each of the sliding pieces 60 moves in the forward and backward directions, so there is no need to arrange multiple springs that individually bias each of the refills 5 connected to the sliding pieces 60. In other words, a multi-core and knock-type writing instrument can be realized with a single front spring 11. As a result, the writing instrument 1 can reduce the proportion of the retraction mechanism and the refill selection mechanism to the total length in the axial direction, and the outer diameter of the writing instrument 1 can be made thinner, and it can be a simple mechanism. In addition, by arranging the single front spring 11 outside the spacer 30, that is, near the inner peripheral surface of the shaft tube 4, it is possible to prevent the refill 5 from coming into contact with the front spring 11 and being damaged. In other words, since the rail portion 32 of the spacer 30 covers most of the outer peripheral surface facing radially outward of the refill 5, the refill 5 does not come into contact with the front spring 11. Furthermore, because there are no multiple operating parts arranged on the outer peripheral surface of the writing instrument 1, there are few projections and recesses, making it possible to print patterns or apply decorations.

The barrel 4 may have an opening on its side or may be made transparent or translucent so that it is possible to distinguish which refill 5 is in a writing state by the knock operation, i.e., which refill 5 is in the selected position. Specifically, when an opening is provided on the side of the barrel 4, an opening may be formed on the side of the barrel 4 corresponding to each sliding top 60 so that the opening is visible only when the sliding top 60 is in the forward position. The sliding top 60 may be colored the same color as the writing color of the inserted refill 5.

In the above embodiment, the writing instrument 1 has three refills 5, but it may have two or four or more, and one of them may be a multi-type writing instrument with another type of refill such as a mechanical pencil, marking pen, touch pen, eraser, or friction material instead of a ballpoint refill. Also, the writing instrument 1 is provided with an erasing member 7 at its rear end for erasing handwriting made by the writing instrument 1, but in addition to or instead of this, an erasing member may be provided at a different location on the writing instrument 1. For example, the erasing member may be provided at a part of the front shaft 2, such as the front end, or the erasing member may be provided on the clip.

In the above embodiment, specific examples such as protrusions, grooves, and cam structures are shown, but as long as the same effect is achieved, the components may be configured with different numbers, shapes, or independent parts.

At least one of the refills 5 in the above-described embodiment may be a refill containing a thermochromic ink containing a thermochromic coloring material. In this case, the writing instrument 1 is a thermochromic writing instrument, and the writing of the writing instrument 1 can be thermochromic due to frictional heat generated when rubbed by a friction body serving as an erasing member.

Here, thermochromic ink refers to ink that has the property of maintaining a predetermined color (first color) at room temperature (e.g., 25°C), changing to another color (second color) when heated to a predetermined temperature (e.g., 60°C), and then returning to the original color (first color) when cooled to a predetermined temperature (e.g., -5°C). In a writing instrument 1 using thermochromic ink, the second color is made colorless, and the term "erasing" refers to heating a line drawn in the first color (e.g., red) to make it colorless. Thus, the line is rubbed against the writing surface on which it was drawn with a friction body to generate frictional heat, which changes the drawn line to colorless, i.e., erases it. Naturally, the second color may be a color other than colorless.

The thermochromic microencapsulated pigment that serves as the thermochromic coloring material is not particularly limited as long as it has the ability to change color due to heat such as frictional heat, for example, from colored to colorless, from colored to colored, or from colorless to colored, and various types can be used, and examples of such materials include microencapsulated thermochromic compositions that contain at least a leuco dye, a color developer, and a color change temperature regulator.

The leuco dyes that can be used are not particularly limited, so long as they are electron-donating dyes that function as color-developing agents. Specifically, in order to obtain inks with excellent color-developing properties, conventionally known dyes such as triphenylmethane, spiropyran, fluoran, diphenylmethane, rhodamine lactam, indolylphthalide, and leucoauramine can be used alone (one type) or in a mixture of two or more types (hereinafter simply referred to as "at least one type").

Specifically, 6-(dimethylamino)-3,3-bis[4-(dimethylamino)phenyl]-1(3H)-isobenzofuranone, 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide, 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4 -Azaphthalide, 1,3-dimethyl-6-diethylaminofluoran, 2-chloro-3-methyl-6-dimethylaminofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-xylidinofluoran, 2-(2-chloroanilino)-6-dibutylaminofluoran, 3,6-dimethoxyfluoran, 3,6-di- n-Butoxyfluoran, 1,2-Benz-6-diethylaminofluoran, 1,2-Benz-6-dibutylaminofluoran, 1,2-Benz-6-ethylisoamylaminofluoran, 2-Methyl-6-(N-p-tolyl-N-ethylamino)fluoran, 2-(N-phenyl-N-methylamino)-6-(N-p-tolyl-N-ethylamino)fluoran, 2-(3'-trifluoromethylanilino)-6-diethylamino Fluoran, 3-chloro-6-cyclohexylaminofluoran, 2-methyl-6-cyclohexylaminofluoran, 3-di(n-butyl)amino-6-methoxy-7-anilinofluoran, 3,6-bis(diphenylamino)fluoran, methyl-3',6'-bisdiphenylaminofluoran, chloro-3',6'-bisdiphenylaminofluoran, 3-methoxy-4-dodecoxystyrinoquinoline, etc.

These leuco dyes have a lactone skeleton, a pyridine skeleton, a quinazoline skeleton, a bisquinazoline skeleton, etc., and color is generated by opening these skeletons (rings).

The color developer that can be used is a component that has the ability to cause the leuco dye to develop color, and examples of such compounds include phenolic resin compounds, salicylic acid metal chlorides, salicylic acid resin metal salt compounds, and solid acid compounds.

Specifically, o-cresol, tertiary butyl catechol, nonylphenol, n-octylphenol, n-dodecylphenol, n-stearylphenol, p-chlorophenol, p-bromophenol, o-phenylphenol, hexafluorobisphenol, n-butyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, resorcinol, dodecyl gallate, 2,2-bis(4'-hydroxyphenyl)propane, 4,4-dihydroxydiphenyl sulfone, 1,1-bis(4'-hydroxyphenyl)ethane, 2,2-bis(4'-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl)sulfide, 1-phenyl-1,1-bis( 1,1-bis(4'-hydroxyphenyl)ethane, 1,1-bis(4'-hydroxyphenyl)-3-methylbutane, 1,1-bis(4'-hydroxyphenyl)-2-methylpropane, 1,1-bis(4'-hydroxyphenyl)n-hexane, 1,1-bis(4'-hydroxyphenyl)n-heptane, 1,1-bis(4'-hydroxyphenyl)n-octane, 1,1-bis(4'-hydroxyphenyl)n-nonane, 1,1-bis(4'-hydroxyphenyl)n-decane, 1, At least one of 1-bis(4'-hydroxyphenyl)n-dodecane, 2,2-bis(4'-hydroxyphenyl)butane, 2,2-bis(4'-hydroxyphenyl)ethylpropionate, 2,2-bis(4'-hydroxyphenyl)-4-methylpentane, 2,2-bis(4'-hydroxyphenyl)hexafluoropropane, 2,2-bis(4'-hydroxyphenyl)n-heptane, and 2,2-bis(4'-hydroxyphenyl)n-nonane may be mentioned.

The amount of developer used can be selected according to the desired color density and is not particularly limited, but it is usually preferable to select an amount within the range of about 0.1 to 100 parts by weight per 1 part by weight of the above-mentioned leuco dye.

The discoloration temperature regulator that can be used is a substance that controls the discoloration temperature in the color development of the leuco dye and the color developer. The discoloration temperature regulator that can be used is a conventionally known one. Specific examples include alcohols, esters, ketones, ethers, acid amides, azomethines, fatty acids, and hydrocarbons.

More specifically, at least one of bis(4-hydroxyphenyl)phenylmethane dicaprylate (C ₇ H ₁₅ ), bis(4-hydroxyphenyl)phenylmethane dilaurate (C ₁₁ H ₂₃ ), bis(4-hydroxyphenyl)phenylmethane dimyristate (C ₁₃ H ₂₇ ), bis(4-hydroxyphenyl)phenylethane dimyristate (C ₁₃ H ₂₇ ), bis(4-hydroxyphenyl)phenylmethane dipalmitate (C ₁₅ H ₃₀ ), bis(4-hydroxyphenyl)phenylmethane dibehenate (C ₂₁ H ₄₃ ), bis(4-hydroxyphenyl)phenylethylhexylidene dimyristate (C ₁₃ H ₂₇ ) and the like can be mentioned.

The amount of the discoloration temperature regulator used can be appropriately selected depending on the desired hysteresis width and color density at the time of color development, and is not particularly limited, but it is usually preferable to use it in the range of about 1 to 100 parts by weight per 1 part by weight of the leuco dye.

The thermochromic microencapsulated pigment can be produced by microencapsulating a thermochromic composition containing at least the above leuco dye, color developer, and color change temperature regulator so that the average particle size is 0.1 to 5 μm. Examples of microencapsulation methods include interfacial polymerization, interfacial polycondensation, in situ polymerization, liquid curing coating, phase separation from an aqueous solution, phase separation from an organic solvent, melt dispersion cooling, air suspension coating, and spray drying, and can be appropriately selected depending on the application.

For example, in the phase separation method from an aqueous solution, the leuco dye, developer, and discoloration temperature regulator are heated and melted, then added to an emulsifier solution, heated and stirred to disperse them into oil droplets, and then a resin raw material is gradually added as a capsule membrane agent, such as an amino resin solution or an isocyanate resin solution, which is allowed to continue reacting and then the dispersion is filtered to produce the desired thermochromic microcapsule pigment.

The content of these leuco dyes, color developers, and color change temperature regulators varies depending on the type of leuco dyes, color developers, and color change temperature regulators used, the microencapsulation method, etc., but the mass ratio is 0.1 to 100 parts of color developer and 1 to 100 parts of color change temperature regulator per 1 part of the dye. The mass ratio of the capsule membrane agent to the capsule contents is 0.1 to 1.

The thermochromic microcapsule pigment can be set to an appropriate temperature for each color's color development temperature (for example, color development at -20°C or higher) and color loss temperature (for example, color loss at 60°C or higher) by appropriately combining the types and amounts of the above-mentioned leuco dye, color developer, and color change temperature regulator, and it is preferable that the color changes from colored to colorless due to heat such as frictional heat.

In the case of thermochromic microcapsule pigments, in order to further improve the line density, storage stability, and writing ability, it is preferable that the wall film is formed of a urethane resin, a urea/urethane resin, an epoxy resin, or an amino resin. Examples of urethane resins include compounds of isocyanate and polyol. Examples of epoxy resins include compounds of epoxy resin and amine. Examples of amino resins include melamine resin, urea resin, and benzoguanamine resin. The thickness of the wall film of the microcapsule color material is appropriately determined depending on the required wall film strength and line density.

The average particle diameter of the thermochromic microencapsulated pigment is preferably 0.1 to 5 μm, and more preferably 0.3 to 3 μm, in terms of coloring ability, color development, ease of fading, stability, fluidity in the ink, suppression of adverse effects on writing, and compatibility with the photochromic microencapsulated pigment described below. The "average particle diameter" specified here is the value obtained by measuring the average particle diameter (50% diameter) (refractive index 1.8) using a particle size analyzer [Microtrac HRA9320-X100 (manufactured by Nikkiso)].

If the average particle size is less than 0.2 μm, sufficient line density cannot be obtained, while if it exceeds 5 μm, it is undesirable because it deteriorates writing properties, reduces the dispersion stability of the thermochromic microencapsulated pigment, and is prone to ink back caused by vibration. Furthermore, the 90% diameter is 8 μm or less, preferably 6 μm or less. If a certain proportion of particles with large diameters are present, the above-mentioned effects tend to become more pronounced. Note that the microencapsulated pigment that falls within the above-mentioned average particle size range (0.1 to 5 μm) varies depending on the microencapsulation method, but in a phase separation method from an aqueous solution, it can be prepared by appropriately combining the stirring conditions when manufacturing the microencapsulated pigment.

The specific gravity of the thermochromic microencapsulated pigment is in the range of 0.9 to 1.3, preferably 1.0 to 1.2. If the specific gravity is outside this range, the dispersion stability of the microencapsulated pigment is likely to decrease. Furthermore, microencapsulated pigments with a specific gravity exceeding 1.3 are prone to ink back caused by vibration.

In addition to the thermochromic microencapsulated pigment, the aqueous ink composition for writing instruments may contain water (tap water, purified water, distilled water, ion-exchanged water, pure water, etc.) as the solvent as the remainder, and may also contain water-soluble organic solvents, thickeners, lubricants, rust inhibitors, preservatives, or antibacterial agents as appropriate, within the scope of not impairing the effects of the agent, depending on the intended use of the writing instrument (ballpoint pen, marking pen, etc.).

Examples of water-soluble organic solvents that can be used include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, 3-butylene glycol, thiodiethylene glycol, and glycerin, as well as ethylene glycol monomethyl ether and diethylene glycol monomethyl ether, which can be used alone or in combination.

Of these, it is preferable to use glycerin to prevent ink solidification at the writing area due to the ink bag, and the amount added is preferably 1 to 10% by mass of the total amount of ink. The mechanism of action of glycerin is unknown, but it is presumed to have the effect of reducing the cohesive force between the pigment and ink components in a dry state.

As the thickener that can be used, for example, at least one selected from the group consisting of synthetic polymers, cellulose, and polysaccharides is preferable. Specific examples include gum arabic, tragacanth gum, guar gum, locust bean gum, alginic acid, carrageenan, gelatin, xanthan gum, welan gum, succinoglycan, diutan gum, dextran, methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, starch glycolic acid and its salts, propylene glycol alginate, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, polyacrylic acid and its salts, carboxyvinyl polymer, polyethylene oxide, copolymer of vinyl acetate and polyvinylpyrrolidone, crosslinked acrylic acid polymer and its salts, non-crosslinked acrylic acid polymer and its salts, styrene acrylic acid copolymer and its salts, etc.

Of these, it is preferable to use polysaccharides. Due to their rheological properties, polysaccharides tend to be less susceptible to the effects of vibration on fluidity, and are less likely to cause problems such as poor writing caused by ink bag. Xanthan gum is particularly preferable, as it provides an excellent balance with other properties required of writing instrument inks.

Lubricants include fatty acid esters of polyhydric alcohols, which are also used as surface treatment agents for pigments, higher fatty acid esters of sugars, polyoxyalkylene higher fatty acid esters, alkyl phosphate esters, alkyl sulfonates of higher fatty acid amides, alkyl aryl sulfonates, derivatives of polyalkylene glycols, fluorine-based surfactants, polyether-modified silicones, etc. Rust inhibitors include benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, saponins, etc. Preservatives or antibacterial agents include phenol, sodium omadine, sodium benzoate, benzimidazole-based compounds, etc.

This aqueous ink composition for writing instruments can be produced by a conventional method, for example, by blending the thermochromic and photochromic microencapsulated pigments and the other aqueous components in predetermined amounts and stirring and mixing them with a stirrer such as a homomixer or a disperser. If necessary, coarse particles in the ink composition may be removed by filtration or centrifugation.

The viscosity value of the aqueous ink composition for writing instruments is preferably 500 to 2000 mPa·s at 25° C. and a shear rate of 3.83/s, and 20 to 100 mPa·s at a shear rate of 383/s. By setting the viscosity within the above range, an ink having excellent writing properties and stability over time can be obtained. Furthermore, the non-Newtonian viscosity index n calculated by the viscosity formula S=αD ⁿ (where 1>n>0) (S is shear stress (dyn/cm ² ), D is shear rate (s ⁻¹ ), and α is a non-Newtonian viscosity coefficient) is preferably 0.2 to 0.6. By setting the non-Newtonian viscosity index n within the above range in addition to the above viscosity range, it is possible to appropriately set the fluidity of the ink against vibration, and it is possible to prevent the occurrence of ink back.

The surface tension of the aqueous ink composition for writing instruments is preferably 25 to 45 mN/m, and more preferably 30 to 40 mN/m. Within this range, the balance between the wettability of the inside of the pen tip and the ink is appropriate, making it possible to prevent the occurrence of ink back.

In the refill, an ink follower may be placed immediately behind the ink. The material constituting the follower may be composed of at least a non-volatile or low-volatility organic solvent and a thickener. The non-volatile or low-volatility organic solvent used in the ink follower is used as the base oil of the ink follower, and liquid paraffin is used, for example. Mineral oil and chemically synthesized oil are used for the liquid paraffin, and polybutene, poly-α-olefin, ethylene α-olefin oligomer, etc. can be used as the chemically synthesized oil.

Specific examples of mineral oils that can be used include commercially available Diana Process Oil NS-100, PW-32, PW-90, NR-68, and AH-58 (manufactured by Idemitsu Kosan Co., Ltd.).

Specific examples of polybutenes that can be used include commercially available products such as Nissan Polybutene 200N, Polybutene 30N, Polybutene 10N, Polybutene 5N, Polybutene 3N, Polybutene 015N, Polybutene 06N, and Polybutene 0N (all manufactured by Nippon Oil & Fats Corporation), Polybutene HV-15 (manufactured by Nippon Petrochemical Industry Co., Ltd.), and 35R (manufactured by Idemitsu Kosan Co., Ltd.).

Specific examples of poly-α-olefins that can be used include commercially available barrel process oils P-26, P-46, P-56, P-150, P-350, P-1500, P-2200, (P-10000, P-37500) (manufactured by Matsumura Oil Co., Ltd.).

Specific examples of ethylene α-olefin oligomers that can be used include commercially available products such as LUCANT HC-10, HC-20, HC-100, HC-150, (HC-600, HC-2000) (all manufactured by Mitsui Chemicals, Inc.).

These non-volatile or low-volatile organic solvents can be used alone or in combination of two or more.

Examples of thickeners used in the ink follower include calcium salts of phosphate esters, fine silica particles, block copolymers of polystyrene-polyethylene/butylene rubber-polystyrene, block copolymers of polystyrene-polyethylene/propylene rubber-polystyrene, hydrogenated styrene-butadiene rubber, block copolymers of styrene-ethylenebutylene-olefin crystals, block copolymers of olefin crystals-ethylenebutylene-olefin crystals, and acetoalkoxyaluminum dialkylates, and these can be used alone or in combination of two or more.

Preferred commercially available calcium salts of phosphate esters that can be used include Crodax DP-301LA (manufactured by Croda Japan Co., Ltd.). Usable fine particle silica includes hydrophilic fine particle silica and hydrophobic fine particle silica. Preferred commercially available hydrophilic silica products include AEROSIL-300 and AEROSIL-380 (manufactured by Nippon Aerosil Co., Ltd.), and preferred commercially available hydrophobic silica products include AEROSIL-974D and AEROSIL-972 (manufactured by Nippon Aerosil Co., Ltd.).

Preferable commercially available polystyrene-polyethylene/butylene rubber-polystyrene block copolymers include Kraton GFG-1901X and Kraton GG-1650 (both manufactured by Shell Japan), Septon 8007 and Septon 8004 (both manufactured by Kuraray Co., Ltd.), etc. Preferable commercially available polystyrene-polyethylene/propylene rubber-polystyrene block copolymers include Kraton GG-1730 (manufactured by Shell Japan), Septon 2006 and Septon 2063 (both manufactured by Kuraray Co., Ltd.), etc.

Preferred commercially available hydrogenated styrene-butadiene rubber products include DYNARON 1320P, DYNARON 1321P (both manufactured by JSR Corporation), Tuftec H1041, and Tuftec H1141 (both manufactured by Asahi Chemical Industry Co., Ltd.).

Preferred commercially available products of styrene-ethylenebutylene-olefin crystalline block copolymers include DYNARON 4600P (manufactured by JSR Corporation), and preferred commercially available products of olefin crystalline-ethylenebutylene-olefin crystalline block copolymers include DYNARON 6200P and DYNARON 6201B (manufactured by JSR Corporation).

Preferred commercially available acetoalkoxyaluminum dialkylates include PLENACT AL-M (manufactured by Ajinomoto Fine-Techno Co., Ltd.).

Among these thickeners, in order to further exert the effects of the present invention, it is preferable to use thermoplastic olefin-based elastomers such as styrene-ethylenebutylene-olefin crystalline block copolymers and olefin crystalline-ethylenebutylene-olefin crystalline block copolymers.

Furthermore, in order to obtain an ink follower that prevents the occurrence of ink back, it is preferable that the average tan δ value measured for each frequency while exponentially increasing in the frequency range of 1 to 63 rad/s is 1.0 or more, and more preferably 1.7 to 3.4.

Here, tan δ is a value that means the loss modulus/storage modulus, and it has been known in the past that the average tan δ value measured for each frequency while exponentially increasing in the frequency range "1 to 63 rad/s" is preferably 1.0 or less. In the present invention, by making the average tan δ value measured for each frequency in the above 1 to 63 rad/s 1.0 or more, it becomes possible to absorb vibrations and prevent the occurrence of ink back.

Materials that can be used to form the friction body include thermosetting rubbers such as silicone rubber, nitrile rubber, ethylene propylene rubber, and ethylene propylene diene rubber, as well as thermoplastic elastomers such as styrene-based elastomers, olefin-based elastomers, polyester-based elastomers, and urethane-based elastomers, as well as mixtures of two or more rubber elastic materials and mixtures of rubber elastic materials and synthetic resins. These are configured to produce a Taber abrasion amount of less than 25 mg on the abrasion wheel CS-17 of a Taber abrasion tester under a load of 9.8 N and 1000 rpm in an abrasion test (ASTM D1044) specified in JIS K7204, to form the friction body.

Alkyl sulfonic acid phenyl ester and cyclohexane dicarboxylic acid ester may be added to the material of the friction body. By including alkyl sulfonic acid phenyl ester and cyclohexane dicarboxylic acid ester in the friction body, it becomes possible to erase handwriting without damaging the paper surface and without blurring the printed characters. Furthermore, it is preferable that the friction body has a durometer A hardness of 60 or more as specified in JIS K6203. This ensures a predetermined hardness and enables a more stable rubbing operation. The friction body can also be used as a touch pen or a stylus pen, and may be made conductive.

The friction body is preferably colored with a color having a lower brightness value than the color of the thermochromic ink contained in the writing instrument 1. In other words, if the thermochromic ink of the writing instrument 1 is transferred to the surface of the friction body without discoloring during use of the friction body, the transfer of the thermochromic ink can be made less noticeable. In particular, by making the color of the friction body black or having a brightness value of 2.5 or less, it is possible to make the stains on the surface of the friction body that occur during use less noticeable.

The brightness value is determined by using the Munsell color system with a measuring device such as a general-purpose color difference meter (TC-8600A, manufactured by Tokyo Denshoku Co., Ltd.), measuring the brightness value of the friction body on its surface, and the brightness value of the thermochromic ink is determined by measuring the ink on a line drawn on paper (former JIS P3201; wood-free paper made from 100% chemical pulp, basis weight range 40-157 g/m2, whiteness 75.0% or more) at a writing speed of 4.5 m/min with a pitch interval of 0.1 mm.

In addition, at least one of the multiple refills 5 in the above-mentioned embodiment may be a refill containing mechanical pencil lead, pencil lead, or eraser-erasable ink, and at least one of the remaining refills 5 may be a refill containing thermochromic ink. In this case, by using a plastic eraser or eraser as the erasing member 7, handwriting made with mechanical pencil lead, pencil lead, or eraser-erasable ink can be erased. Furthermore, handwriting made with thermochromic ink can be thermally discolored by rubbing it with a plastic eraser or eraser to generate frictional heat.

Therefore, a plastic eraser or rubber eraser can be used as an erasing material for different types of handwriting, i.e., as an erasing material for erasing handwriting made with mechanical pencil lead, pencil lead, or eraser-erasable ink, and as a friction body for thermally discoloring (erasing) handwriting made with thermochromic ink. Note that the ability to erase handwriting using a plastic eraser or rubber means that handwriting can be erased by rubbing the handwriting with a plastic eraser or rubber without soiling the paper surface around the handwriting.

The mechanical pencil lead or pencil lead preferably contains, for example, 3 to 80% by weight of glass powder in flake form with an average thickness of 0.1 to 2 μm, an aspect ratio of 5 to 150, and a flatness of 200 nm or less, in which at least one type of fine particle (excluding glass powder) selected from inorganic pigments, organic pigments, and dyes is dispersed or encapsulated as a compound composition before firing, or glass powder in granular form with an average particle size of 0.1 to 50 μm and a sphericity of 0.1 to 50 μm.

The eraser-erasable ink preferably contains at least 5-30% by weight of non-thermoplastic colored resin particles with an average particle size of 2-20 μm relative to the total amount of the ink composition, and non-colored particles with a glass transition point of less than 0°C. As mentioned above, the "average particle size" specified here is the value obtained by measuring the average particle size (50% diameter) (refractive index 1.8) using a particle size analyzer [Microtrac HRA9320-X100 (manufactured by Nikkiso)].

In this case, the friction body contains, in addition to the friction body described above, an acrylic thermoplastic resin powder having a primary particle size of 20 to 80 μm, which is composed of a shell with a relatively high glass transition temperature (Tg) and a core with a relatively lower glass transition temperature (Tg) than the shell, a plasticizer, an inorganic powder, and a thermoplastic resin, in which the thermoplastic resin is polyvinyl chloride resin or a copolymer thereof, and the inorganic powder is calcium carbonate and/or magnesium carbonate, since both the thermochromic ink mark and the erasable ink mark can be affected by rubbing. The "glass transition temperature (Tg)" refers to the temperature at which the mobility of the non-crystalline portion of the acrylic resin powder increases and it becomes rubbery.

Figure 25 is a perspective view of a writing instrument 201 according to another embodiment of the present invention. The writing instrument 201 differs from the writing instrument 1 according to the above-described embodiment in the shape of the rear shaft and spacer, but other components are the same or substantially the same, so only the differences will be described.

26 is a vertical cross-sectional view of the rear barrel 203. In the assembled state of the writing instrument 1, the rear barrel 203 is arranged so that the upper side in FIG. 26 is the rear side of the writing instrument 201. On the inner peripheral surface of the rear barrel 203, two approximately I-shaped slender protrusions 213 are provided as locking portions. The two slender protrusions 213 are arranged 120 degrees apart around the central axis. The slender protrusions 213 may not be provided on the inner peripheral surface of the rear barrel 203, but may be provided as separate members, for example. The position of the front end of the slender protrusions 213 on the rear barrel 203 is the same as the position of the front end of the T-shaped protrusion 13 on the rear barrel 3 of the corresponding writing instrument 1. However, the position of the rear end of the slender protrusions 213 on the rear barrel 203 is located forward of the position of the rear end of the T-shaped protrusion 13 on the rear barrel 3 of the writing instrument 1. That is, the axial length of the elongated protrusion 213 is shorter than the axial length of the T-shaped protrusion 13.

Figure 27 is a perspective view of the spacer 230. In the assembled state of the writing instrument 201, the spacer 230 is arranged so that the upper side in Figure 27 is the rear side of the writing instrument 201. The spacer 230 has a connecting portion 233 formed to connect the rear ends of the three rail portions 32. The connecting portion 233 has three connecting pieces 33a with an outer shape formed to have a diameter slightly smaller than the outer diameter of the three rail portions 32. In other words, the spacer 230 does not have the rotation restriction piece 33b in the spacer 30 of the writing instrument 1. Therefore, in the writing instrument 201, the rear shaft 203 can freely rotate with respect to the front shaft 2. In other words, the rotation of the rear shaft 203 around the axis is not restricted by the abutment between the connecting portion 233 of the spacer 230 and the guide protrusion 53 of the rotating cam 50. A protruding mark portion 235 extending forward is formed on the front end surface of the flange portion 34. The mark portion 235 protrudes radially outward further than the mark portion 35 in the writing instrument 1. Therefore, in the writing instrument 201, the mark portion 235 protrudes from the outer surface of the barrel 4 to an extent that it can be clearly distinguished by touch with a finger (FIG. 25). This makes it easy to distinguish the connection portion of the front barrel 2 and the rear barrel 3.

Figure 28 is a schematic diagram explaining the operation of the refill during a knock operation. The operation of the refill during a knock operation in the writing instrument 201 is basically the same as the operation of the refill during a knock operation in the writing instrument 1 described above with reference to Figure 22. However, unlike the T-shaped protrusion 13 in the writing instrument 1, the elongated protrusion 213 in the writing instrument 201 is not related to the operation of the refill during a knock operation, and therefore is not illustrated in Figure 28. In the writing instrument 1 in the writing state, as described with reference to Figure 22, two of the three sliding tops 60 are engaged with the T-shaped protrusion 13, and the forward movement of the two sliding tops 60 is restricted. However, in the writing instrument 201, the position of the rear end of the elongated protrusion 213 is located forward of the position of the rear end of the T-shaped protrusion 13 of the writing instrument 1, so the sliding tops 60 do not engage with the elongated protrusion 213.

Here, in the writing instrument 1, in both the non-writing state (FIG. 22(A)) and the writing state (FIG. 22(C)), the sliding top 60 is engaged or approximately engaged with the T-shaped protrusion 13. Therefore, if the writing instrument 1 is accidentally dropped with its front end facing downward, a strong impact will be applied in the axial direction to the sliding top 60 and the refill 5 connected to the sliding top 60. At this time, since the sliding top 60 is engaged with the T-shaped protrusion 13, the refill 5 will be subjected to an inertial force in a direction to come off the sliding top 60.

In contrast, in the writing instrument 201, the sliding top 60 does not engage with the elongated protrusion 213, so even if the writing instrument 201 is dropped with its front end facing downward, the refill 5 moves forward together with the sliding top 60. Therefore, there is no risk of the refill 5 coming off the sliding top 60. In other words, when the writing instrument 201 is in the writing state, the sliding top 60 and the first cam surface 44 are separated, so that only the sliding top 60 is not restricted from moving forward, and there is no risk of the refill 5 coming off the sliding top 60. The forward movement of the refill 5 and the sliding top 60 is restricted by the writing part 5a of the refill 5 abutting against the tapered portion at the front end of the front shaft 2.

REFERENCE SIGNS LIST 1 Writing implement 4 Barrel 5 Refill 7 Erasing member 10 Rear spring 11 Front spring 13 T-shaped projection 20 Inner cylinder 30 Spacer 40 Collar member 50 Rotating cam 60 Sliding piece 70 Operating member 80 Rotor 90 Brake rod 100 Knock ring

Claims (3)

A writing instrument comprising a barrel, a writing body arranged in the barrel and having a writing part, and an eraser capable of erasing handwriting made by the writing body,
The eraser further comprises a brake member movable in the front-rear direction within the barrel, a rotating member which moves together with the eraser and can rotate about a central axis, and a locking portion which can be locked to the rotating member,
A writing instrument characterized in that when the front end of the barrel is pointed upward, the brake member moves rearward, restricting the rotation of the rotating member and causing the rotating member to engage with the locking portion, thereby preventing the eraser from moving forward. 2. The writing implement according to claim 1, characterized in that a protrusion is provided on an inner surface of the rotating member, and the brake member inserted into the rotating member engages with the protrusion, thereby regulating the rotation of the rotating member. The rotating member has a first inclined surface inclined in a circumferential direction with respect to a plane perpendicular to the front-rear direction, and the locking portion has a second inclined surface inclined in a circumferential direction with respect to a plane perpendicular to the front-rear direction,
The writing instrument according to claim 1 or 2, characterized in that the first inclined surface of the rotating member, whose rotation is restricted, abuts the second inclined surface of the engaging portion, thereby preventing the eraser from moving forward, and the inclination angle of the first inclined surface or the second inclined surface relative to the axial direction of the writing instrument is greater than 45 degrees.

Images