Thermochromic writing instruments

Abstract

To provide a thermochromic writing instrument that can maintain the proper shape of the friction element over a long period of time and reliably prevent the friction element from becoming soiled when not in use. [Solution] The pen is equipped with a retractable mechanism that allows the pen tip 61 of the writing body 6 to extend and retract from the front end hole 21a of the barrel 2 by sliding an operating body 4 on the side of the barrel 2 forward. A friction body 3 is provided at the rear end of the barrel 2. The retractable mechanism comprises a cam portion 25 formed inside the barrel 2, a rotating member 5 that engages with the cam portion 25 and abuts against the rear end of the writing body 6, and an operating body 4 that engages with the rotating member 5 in the front and back directions. The friction body 3 and the rotating member 5 are engaged to prevent rotation in the rotational direction of the rotating member 5. The friction body 3 rotates as the rotating member 5 rotates.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a thermochromic writing instrument in which a friction portion is provided at the rear end of a shaft cylinder, an operating body (clip body) is provided on the side wall of the shaft cylinder, and the pen tip can be made to protrude and retract by operating the operating body.

[0003] Patent Document 2 discloses a configuration in which, in the thermochromic writing instrument of Patent Document 1, for the purpose of preventing the friction body from being soiled when not in use, a protective piece portion that is integrally movable in the front-rear direction is provided on the outer periphery near the friction body at the rear end of the shaft cylinder.

[0004] Patent Document 3 discloses a configuration in which, in the thermochromic writing instrument of Patent Document 1, for the purpose of preventing the friction body from being soiled when not in use, a protruding and retracting hole that opens rearward is formed at the top of the friction body, a protective portion is provided so as to be able to protrude and retract freely from the protruding and retracting hole, and the protective portion is continuously provided to the operating body.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] The thermochromic writing instrument described in Patent Document 1 tends to be used by users who check the orientation of the operating body and grip it in the same position during use. If the friction body is used for a long period of time, it may partially wear down, making it difficult to maintain the proper shape of the friction body and making it difficult to properly rub the ink to produce a thermochromic writing line.

[0007] In the thermochromic writing instrument described in Patent Document 2, even when the pen tip is fully submerged, dust may enter through gaps in the protective piece, potentially soiling the top and sides of the friction element.

[0008] The thermochromic writing instrument described in Patent Document 3 may have its side surface soiled even when the pen tip is fully submerged.

[0009] The present invention solves the aforementioned problems of the prior art and provides a thermochromic writing instrument that can maintain the proper shape of the friction body over a long period of time and reliably prevent the friction body from becoming contaminated when not in use. In the present invention, "front" refers to the pen tip side, "rear" refers to the opposite side, "axial direction" refers to the front-to-back direction, and "radial direction" refers to the direction perpendicular to the axial direction. [Means for solving the problem]

[0010] A first aspect of the present invention is a writing body housed inside a barrel so as to be movable in the front-rear direction, a thermochromic ink housed inside the writing body, a pen tip from which the thermochromic ink can be dispensed at the front end of the writing body, an operating body that is movable in the front-rear direction provided on the side of the barrel, the writing body being biased backward by a spring, and a retraction mechanism that allows the pen tip of the writing body to extend and retract from a hole at the front end of the barrel by sliding the operating body forward against the backward bias of the spring, and the rear of the barrel A thermochromic writing instrument equipped with a friction body at its end that can heat-change the color of the ink by friction, thereby generating frictional heat, wherein the retractable mechanism comprises a cam portion formed inside the barrel, a rotating member that engages with the cam portion and abuts against the rear end of the writing body, and an operating body that engages with the rotating member in the front-to-back direction, wherein the friction body and the rotating member are engaged to prevent rotation in the rotational direction of the rotating member, and the friction body rotates as the rotating member rotates.

[0011] According to the first embodiment of the thermochromic writing instrument, the friction wear of the friction element becomes uniform, and the proper shape of the friction element can be maintained over a long period of time.

[0012] A second aspect of the present invention is a thermochromic writing instrument according to the first aspect, wherein a friction body cover is provided at the rear end of the barrel to restrict the rearward movement of the friction body.

[0013] According to the second embodiment of the thermochromic writing instrument, it is possible to prevent the friction element from falling out of the barrel.

[0014] A third aspect of the present invention is a thermochromic writing instrument according to the second aspect, wherein the friction body comprises a friction portion that frictionally rubs against the writing of the thermochromic ink and a friction portion holder that holds the friction portion, and the friction portion holder and the rotating member are engaged to prevent rotation in the rotational direction of the rotating member.

[0015] According to the thermochromic writing instrument of the third embodiment, since the friction part and the rotating member do not directly engage with each other, the anti-rotation engagement between the friction body and the rotating member can be strengthened.

[0016] A fourth aspect of the present invention is a thermochromic writing instrument according to the third aspect, wherein a plurality of friction parts are provided at equal intervals on the outer peripheral edge of the rear end of the friction part holder, the friction body cover is provided so as to cover the friction body, an opening is provided on the outer peripheral edge of the rear end of the friction body cover so as to be exposed to the friction parts of the friction body, the friction body rotates in conjunction with the extension and retraction of the pen tip, each of the friction parts is covered by the friction body cover when the pen tip is retracted, and the friction parts are exposed through the opening when the pen tip is extended.

[0017] According to the thermochromic writing instrument of the fourth embodiment described above, it is possible to reliably prevent the friction material from becoming soiled when not in use.

[0018] A fifth aspect of the present invention is a thermochromic writing instrument according to the second aspect, wherein an opening is provided in the center of the friction body cover that penetrates in the front-to-back direction, and the friction body comprises a friction portion that frictions the writing of the thermochromic ink, and a flange portion formed in front of the friction portion and projecting radially outward, This is a thermochromic writing instrument in which the friction portion protrudes rearward from the opening of the friction body cover, and the flange portion is locked back and forth by a locking wall on the inner surface of the friction body cover.

[0019] According to the thermochromic writing instrument of the fifth embodiment described above, the friction element can be held stably in a rotatable manner, and the friction element can be reliably prevented from falling out of the barrel.

[0020] A sixth aspect of the present invention is a thermochromic writing instrument according to the first or fifth aspect, wherein the friction body comprises a friction portion that frictionally rubs against the writing of the thermochromic ink and a friction portion holder that holds the friction portion, and the friction portion holder and the rotating member are engaged to prevent rotation in the rotational direction of the rotating member.

[0021] According to the thermochromic writing instrument of the sixth embodiment, since the friction part and the rotating member do not directly engage with each other, the anti-rotation engagement between the friction body and the rotating member can be strengthened. [Effects of the Invention]

[0022] According to the thermochromic writing instrument of the present invention, the proper shape of the friction member can be maintained over a long period of time.

Brief Description of the Drawings

[0023] [Figure 1] It is a longitudinal sectional view of the pen tip immersed state of the first embodiment of the thermochromic writing instrument of the present invention. [Figure 2] It is an enlarged longitudinal sectional view of the main part of FIG. 1. [Figure 3] It is a perspective view of the main part of FIG. 2. [Figure 4] It is a longitudinal sectional view of the pen tip protruding state of the first embodiment of the thermochromic writing instrument of the present invention. [Figure 5] It is an enlarged longitudinal sectional view of the main part of FIG. 4. [Figure 6] It is a perspective view of the main part of FIG. 5. [Figure 7] It is a longitudinal sectional view showing the whole parts of the first embodiment of the thermochromic writing instrument of the present invention. [Figure 8] It shows the friction member cover of the first embodiment of the thermochromic writing instrument of the present invention. (a) is a longitudinal sectional view, (b) is a perspective view seen from the rear with the slide hole facing up, and (c) is a perspective view seen from the front with the slide hole facing down. [Figure 9] It shows the friction member of the first embodiment of the thermochromic writing instrument of the present invention. (a) is a perspective view of the whole friction member seen from the rear, (b) is a perspective view of the whole friction member seen from the front, (c) is a perspective view of the friction part constituting the friction member, and (d) is a perspective view of the friction part holder constituting the friction member. [Figure 10] It shows the friction member of the first embodiment of the thermochromic writing instrument of the present invention. (a) is a longitudinal sectional view of the friction member, (b) is a sectional view taken along the line A - A of (a), and (c) is a sectional view taken along the line B - B of (a). <00S0114>It shows the rotating member of the first embodiment of the thermochromic writing instrument of the present invention. (a) is a perspective view seen from the front, and (b) is a perspective view seen from the rear. [Figure 12] This is an enlarged longitudinal cross-sectional view of the main part of the second embodiment of the thermochromic writing instrument of the present invention, with the pen tip fully submerged. [Figure 13] Figure 12 is an external view of the main parts. [Figure 14] This is an enlarged longitudinal cross-sectional view of the main part of the second embodiment of the thermochromic writing instrument of the present invention, with the pen tip protruding. [Figure 15] Figure 14 is an external view of the main parts. [Figure 16] This is a longitudinal cross-sectional view showing the entire component of the second embodiment of the thermochromic writing instrument of the present invention. [Figure 17] This shows the friction body cover of a second embodiment of the thermochromic writing instrument of the present invention, where (a) is a longitudinal cross-sectional view and (b) is a perspective view taken from the rear with the slide hole facing upwards. [Figure 18] This shows a friction body of a second embodiment of the thermochromic writing instrument of the present invention, where (a) is a longitudinal cross-sectional view of the friction body, (b) is a CC cross-sectional view of (a), and (c) is a DD cross-sectional view of (a). [Figure 19] This shows a friction body of a third embodiment of the thermochromic writing instrument of the present invention, where (a) is a longitudinal cross-sectional view of the friction body, (b) is an EE cross-sectional view of (a), and (c) is an FF cross-sectional view of (a). [Modes for carrying out the invention]

[0024] <First Embodiment> Figures 1 to 11 show a thermochromic writing instrument 1 according to the first embodiment of the present invention.

[0025] The thermochromic writing instrument 1 of this embodiment comprises a barrel 2, a writing body 6 housed inside the barrel 2, an operating body 4 protruding radially outward from the side surface of the barrel 2, and a retractable mechanism that allows the pen tip 61 of the writing body 6 to extend and retract from the front end hole 21a of the barrel 2 by sliding the operating body 4 forward.

[0026] ·Cursive The writing instrument 6 consists of a pen tip 61, an ink reservoir 62 into which the pen tip 61 is press-fitted and fixed at its front end opening, a thermochromic ink filled in the ink reservoir 62, and a follower (e.g., a high-viscosity fluid) filled at the rear end of the thermochromic ink that moves forward as the thermochromic ink is consumed.

[0027] Pen nib The pen tip 61 may consist of, for example, a metal ballpoint pen tip that rotatably holds a ball at its front end, or a synthetic resin pen tip holder that holds the rear outer surface of the ballpoint pen tip. A tail plug with a vent hole that allows air to pass between the ink reservoir 62 and the outside is attached to the rear end opening of the ink reservoir 62. Inside the pen tip 61 is a spring that presses the ball at the front end forward. The spring is a compression coil spring with a rod at its front end, and the front end of the rod is in contact with the rear surface of the ball. When not writing, the forward bias of the spring causes the ball to be in close contact with the inner surface of the inwardly facing front edge of the front end of the ballpoint pen tip, preventing ink leakage and evaporation from the front end of the pen tip 61.

[0028] ·Shaft cylinder The shaft cylinder 2 comprises a tapered cylindrical front shaft 21, a cylindrical rear shaft 22 connected to the rear end of the front shaft 21 by screwing, and a cylindrical friction body cover 23 to which the rear end of the rear shaft 22 is attached. The front shaft 21, rear shaft 22, and friction body cover 23 are obtained from molded synthetic resin (e.g., polycarbonate).

[0029] A front end hole 21a is opened at the front end of the front shaft 21. A slide hole 24 extending in the front-rear direction (axial direction) is formed in the rear side wall of the shaft cylinder 2 (the side wall of the rear shaft 22 and the side wall of the friction body cover 23). A cam portion 25 (cam teeth 25a and cam groove 25b) is integrally formed on the inner surface of the shaft cylinder 2 (rear shaft 22).

[0030] • Friction cover The friction body cover 23 is a bottomed cylindrical body and is obtained from a molded synthetic resin (e.g., polycarbonate). The friction body cover 23 is attached to the outer surface of the rear end of the rear shaft 22 by fitting. One opening 23a is formed on the outer peripheral edge of the rear end of the friction body cover 23. The opening 23a is located 180 degrees opposite the axis from the slide hole 24. The opening 23a is notched outwards radially and to the rear. When the pen tip is extended, one friction part 31 of the friction body 3 is exposed to the outside through the opening 23a. The opening 23a may be provided in multiple locations (e.g., four locations) at equal intervals, in which case multiple friction parts 31 (e.g., four friction parts 31) will be exposed or hidden simultaneously by the sliding operation of the operating body 4.

[0031] ·Friction body The friction body 3 comprises a friction portion 31 made of a soft material and a friction portion holder 32 made of a hard material.

[0032] As shown in Figure 9(c), the friction portion 31 comprises a cylindrical core portion 31a through which an inner bore 31d is provided in the axial direction, a plurality of axially extending protrusions 31b (for example, 4) integrally formed at equal intervals on the outer circumferential surface of the core portion 31a, and a plurality of axially extending recesses 31c (for example, 4) formed between adjacent protrusions 31b.

[0033] As shown in Figure 9(d), the friction part holder 32 comprises a disc portion 32a, a front core portion 32b integrally formed forward from the axis of the front surface of the disc portion 32a, a rear core portion 32c integrally formed rearward from the axis of the rear surface of the disc portion 32a, and a plurality (for example, 4) columnar portions 32d integrally formed at equal intervals on the peripheral edge of the rear surface of the disc portion 32a and extending rearward, each having a fan-shaped cross-section.

[0034] An engagement hole 32e is formed in the axis of the friction holder 32, opening forward and extending in the axial direction. The engagement hole 32e is formed in a non-circular cross-section (for example, a cross-shaped cross-section). In addition to a cross-shaped cross-section, other cross-sectional shapes of the engagement hole 32e include, for example, a triangle, a square, a polygon, a star shape, an ellipse, etc.

[0035] The friction body 3 is comprised of a friction portion 31 and a friction portion holder 32 (see Figure 9). Specifically, the rear core portion 32c of the friction portion holder 32 is inserted into the inner hole 31d of the core portion 31a of the friction portion 31, the columnar portion 32d of the friction portion holder 32 is inserted and engaged into the recesses 31c between the convex portions 31b of the friction portion 31, and each convex portion 31b of the friction portion 31 is inserted and engaged between the columnar portions 32d of the friction portion holder 32. The friction body 3 as a whole comprises a front cylindrical portion (front core portion 32b) with a small outer diameter and a rear cylindrical portion with a large outer diameter connected to the rear of the front cylindrical portion. The rear cylindrical portion comprises a disc portion 32a, a convex portion 31b, and a columnar portion 32d.

[0036] The soft material constituting the friction portion 31 is preferably a rubber elastic material (a rubber or elastomer or other material having rubber elasticity), such as silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin (styrene-ethylene-butylene-styrene copolymer), fluororesin, chloroprene resin, nitrile resin, polyester resin, ethylene propylene diene rubber (EPDM), etc. The rubber elastic material constituting the friction portion 31 is not a highly abrasion elastic material (for example, an eraser), but a low abrasion elastic material that produces almost no wear debris (eraser residue) during friction.

[0037] The hard material constituting the friction part holder 32 only needs to be harder than the friction part 31, and examples include synthetic resins (e.g., polycarbonate, polypropylene, polyethylene, polyacetal), metals, etc.

[0038] • Operating body The operating body 4 consists of an operating portion 41 (clip body) extending in the front-rear direction (axial direction), a base portion 42 integrally connected radially inward from the rear of the operating portion 41, and a cylindrical shaft portion 43 integrally connected to the base portion 42 and extending forward from the base portion 42. The operating body 4 is obtained by molding a synthetic resin (for example, polycarbonate resin). The operating body 4 (clip body) has a clamping projection (ball portion) protruding from its back surface. At the front end of the shaft portion 43, cam teeth 44 that engage with the rotating member 5 (specifically, cam teeth 44 that engage with the cam surface 52a at the rear end of the projection 52 of the rotating member 5) are formed integrally or by attachment of a separate member.

[0039] The pen tip extension / retraction mechanism is a side-slide type extension / retraction mechanism using a rotating cam mechanism. The extension / retraction mechanism comprises a cam portion 25 formed on the inner surface of the rear shaft 22, a rotating member 5 that engages with the cam portion 25 and abuts against the rear end of the writing body 6, an operating body 4 that engages with the rotating member 5 and protrudes radially outward from the slide hole 24, and a resilient body 7 (e.g., a compression coil spring) housed inside the barrel 2 and biasing the writing body 6 backward. In this embodiment, the pen tip extension / retraction mechanism is a double-knock type in which both the pen tip extension operation and the pen tip retraction operation involve sliding the operating part 41 forward.

[0040] Cam section The cam portion 25 on the inner surface of the rear shaft 22 comprises a plurality of sawtooth-shaped cam teeth 25a that protrude forward, and a plurality of cam grooves 25b that extend in the front-rear direction and are formed between the cam teeth 25a.

[0041] Rotating member The rotating member 5 comprises a bottomed cylindrical support portion 51 at its front end, a plurality of (for example, four) protrusions 52 extending in the front-rear direction and integrally formed on the outer surface of the support portion 51, and a rod-shaped portion 53 connected to the axis of the support portion 51 and extending rearward from the rear end of the protrusions 52.

[0042] The projection 52 is capable of engaging with the cam portion 25 (cam teeth 25a, cam groove 25b) and also with the cam teeth 44 at the front end of the shaft portion 44. An inclined cam surface 52a is formed at the rear end of the projection 52. The cam surface 52a is capable of engaging with the cam teeth 25a of the cam portion 25 and also with the cam teeth 44 at the front end of the shaft portion 43 of the operating body 4.

[0043] The length of the rod-shaped portion 53 in the front-rear direction (specifically, the axial length from the rear end of the projection 52 to the rear end of the rod-shaped portion 53) is set to be longer than the length of the shaft portion 43 in the front-rear direction. As a result, the rod-shaped portion 53 is inserted inside the cylindrical shaft portion 43 of the operating body 4 and protrudes rearward from the rear end of the shaft portion 43.

[0044] An engaging portion 53a is formed on the outer surface of the rear end of the rod-shaped portion 53, which can engage with the engagement hole 32e of the friction body 3 (the engagement hole 32e of the friction body holder 32). The engaging portion 53a extends in the front-rear direction and has a shape corresponding to the cross-sectional shape of the engagement hole 32e (for example, a cross-shaped cross section). The engaging portion 53a of the rod-shaped portion 53 of the rotating member 5 is always engaged with the engagement hole 32e of the friction body 3 to prevent rotation (i.e., in the pen tip protruding state, the pen tip protruding state, and the state between the pen tip protruding state and the pen tip retracted state), and the engaging portion 53a of the rod-shaped portion 53 of the rotating member 5 and the engagement hole 32e of the friction body 3 are configured to slide axially (for example, even when the operating body 4 is pressed to its maximum forward position, the engaging portion 53a of the rod-shaped portion 53 of the rotating member 5 and the engagement hole 32e of the friction body 3 remain engaged to prevent rotation, and the engaging portion 53a does not fall out of the engagement hole 32e). As a result, the axial movement of the rotating member 5 is maintained, proper engagement and disengagement operation between the protrusion 52 and the cam portion 25 (cam teeth 25a, cam groove 25b) is achieved, and proper operation of the retractable mechanism is obtained.

[0045] • Rotational operation of friction body When the operating part 41 (clip body) is slid forward against the rearward biasing force of the elastic body 7 from the pen tip retracted state, the operating part 41 presses the rotating member 5 forward, which presses the rear end of the writing body 6 forward, causing the pen tip 61 to protrude outward from the front end hole 21a. At this time, the rotating member 5 engages with the cam part 25 (specifically, the protrusion 52 engages with the cam teeth 25a), and the pen tip protruding state is maintained. In the process of transitioning from the pen tip retracted state to the pen tip protruding state, the rotating member 5 rotates by a certain angle (for example, 45 degrees), and the friction body 3 rotates by a certain angle (for example, 45 degrees) in conjunction with the rotation of the rotating member 5. In the pen tip protruding state, one of the friction parts 31 of the friction body 3 is exposed to the outside through the opening 23a of the friction body cover 23. The exposed friction part 31 can be used to rub the writing of thermochromic ink.

[0046] Next, when the operating part 41 (clip body) is slid forward against the rearward biasing force of the elastic body 7 from the pen tip protruding state, the operating part 41 presses the rotating member 5 forward, and the rotating member 5 presses the rear end of the writing body 6 forward, disengaging the protrusion 52 of the rotating member 5 from the cam teeth 25a, and the protrusion 52 from the cam groove 25b engages with it, causing the pen tip 61 to retract into the barrel 2 through the front end hole 21a. In the process of transitioning from the pen tip protruding state to the pen tip retracted state, the rotating member 5 rotates by a certain angle (for example, 45 degrees), and the friction body 3 rotates by a certain angle (for example, 45 degrees) in conjunction with the rotation of the rotating member 5. In the pen tip retracted state, all friction parts 31 of the friction body 3 are covered by the friction body cover 23, thereby preventing the friction parts 31 from becoming dirty when not in use (when not writing and when the friction body is not in use). Furthermore, the angle at which the rotating member 5 rotates in a single slide operation can be set to 60 degrees, in addition to the aforementioned 45 degrees.

[0047] Next, when the pen tip is extended again from the retracted state using the same operation, one of the friction parts 31 of the friction body 3 is exposed. At this time, the friction part 31 exposed from the opening 23a is different from the friction part 31 exposed when the pen tip was extended in the previous state. In other words, the friction parts 31 are sequentially exposed one by one from the opening 23a by the pen tip extension and retraction operation. As a result, the entire friction part 31 is used uniformly, and the proper shape of the friction body 3 can be maintained over a long period of time.

[0048] The thermochromic writing instrument 1 of this embodiment includes a writing body 6 housed inside a barrel 2 so as to be movable in the front-rear direction, thermochromic ink housed inside the writing body 6, a pen tip 61 at the front end of the writing body 6 from which the thermochromic ink can be dispensed, an operating body 4 that is movable in the front-rear direction provided on the side of the barrel 2, a mechanism for extending and retracting the pen tip 61 of the writing body 6 that allows it to extend and retract from the front end hole 21a of the barrel 2 by sliding the operating body 4 forward against the rearward bias of the elastic body 7. The thermochromic writing instrument is equipped with a friction body 3 at the rear end of the barrel 2 that can change the color of the ink by friction, generating frictional heat. The retractable mechanism comprises a cam portion 25 formed inside the barrel 2, a rotating member 5 that engages with the cam portion 25 and abuts against the rear end of the writing body 6, and an operating body 4 that engages with the rotating member 5 in the front-to-back direction. The friction body 3 and the rotating member 5 are engaged to prevent rotation in the rotational direction of the rotating member 5, and the friction body 3 rotates as the rotating member 5 rotates. As a result, the thermochromic writing instrument 1 of this embodiment has uniform wear due to friction of the friction body 3, and can maintain the proper shape of the friction body 3 over a long period of time.

[0049] The thermochromic writing instrument 1 of this embodiment is a thermochromic writing instrument in which a friction body cover 23 is provided at the rear end of the barrel 2 to restrict the rearward movement of the friction body 3. As a result, the thermochromic writing instrument 1 of this embodiment can prevent the friction body 3 from falling out of the barrel 2.

[0050] The thermochromic writing instrument 1 of this embodiment comprises a friction body 3 having a friction part 31 that rubs against the writing of the thermochromic ink and a friction part holder 32 that holds the friction part 31, and the friction part holder 32 and the rotating member 5 are engaged in a rotation-preventing engagement in the rotational direction of the rotating member 5. As a result, in the thermochromic writing instrument 1 of this embodiment, the friction part 31 and the rotating member 5 do not directly engage with each other, so the rotation-preventing engagement between the friction body 3 and the rotating member 5 can be made stronger.

[0051] The thermochromic writing instrument 1 of this embodiment is a thermochromic writing instrument in which the friction parts 31 are provided at equal intervals on the outer peripheral edge of the rear end of the friction part holder 32, the friction body cover 23 is provided so as to cover the friction body 3, an opening 23a is provided on the outer peripheral edge of the rear end of the friction body cover 23 so as to be exposed to the friction parts 31 of the friction body 3, the friction body 3 rotates in conjunction with the extension and retraction of the pen tip 61, each of the friction parts 31 is covered by the friction body cover 23 when the pen tip is retracted, and the friction parts 31 are exposed through the opening 23a when the pen tip is extended. As a result, the thermochromic writing instrument 1 of this embodiment can reliably prevent the friction body 3 from becoming dirty when not in use.

[0052] Furthermore, in this embodiment, the thermochromic writing instrument 1 allows the friction element 3 to be exposed and concealed by extending and retracting the pen tip 61.

[0053] <Second Embodiment> A thermochromic writing instrument 1 according to a second embodiment of the present invention is shown in Figures 12 to 18.

[0054] The thermochromic writing instrument 1 of this embodiment is a modified version of the first embodiment, with the friction element 3 and friction element cover 23 having different configurations from the first embodiment, while the other configurations are the same as the first embodiment.

[0055] • Friction cover The friction body cover 23 is cylindrical and is obtained from a molded synthetic resin (e.g., polycarbonate). An opening 23b is provided in the center of the friction body cover 23, penetrating in the front-rear direction. An annular locking wall portion 23c is provided protruding from the inner surface of the rear end of the friction body cover 23. The opening 23b is formed on the inner surface of the locking wall portion 23c. The opening 23b is formed in the center of the friction body cover 23. The friction portion 3c of the friction body 3 always protrudes rearward from the opening 23b of the friction body cover 23, and the flange portion 3a of the friction body 3 is locked front-rear by the locking wall portion 23c of the friction body cover 23.

[0056] ·Friction body The friction body 3 comprises a flange portion 3a, a front core portion 3b integrally formed on the front surface of the flange portion 3a, and a friction portion 3c having a convex curved top integrally formed on the rear surface of the flange portion 3a. The flange portion 3a is held between the rear end of the rear shaft 2 and the locking wall portion 23c with a small amount of play in the front-to-back direction. This allows the friction body 3 to rotate around its axis.

[0057] An engagement hole 3d is formed in the axis of the friction body 3, opening forward and extending in the axial direction. The engagement hole 3d is formed in a non-circular cross-section (for example, a cross-shaped cross-section). In addition to a cross-shaped cross-section, other cross-sectional shapes of the engagement hole 3d include, for example, a triangle, a square, a polygon, a star shape, an ellipse, etc.

[0058] The friction body 3 is preferably made of a rubber elastic material (a rubber or elastomer or other rubber elastic material), such as silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin (styrene-ethylene-butylene-styrene copolymer), fluororesin, chloroprene resin, nitrile resin, polyester resin, ethylene propylene diene rubber (EPDM), etc. The rubber elastic material constituting the friction body 3 is not a highly abrasion elastic material (for example, an eraser), but a low abrasion elastic material that produces almost no wear debris (eraser shavings) during friction.

[0059] • Rotational operation of friction body When the operating part 41 (clip body) is slid forward against the rearward biasing force of the elastic body 7 from the pen tip retracted state, the operating part 41 presses the rotating member 5 forward, and the rotating member 5 presses the rear end of the writing body 6 forward, causing the pen tip 61 to protrude outward from the front end hole 21a. At this time, the rotating member 5 engages with the cam part 25 (specifically, the protrusion 52 engages with the cam teeth 25a), and the pen tip protruding state is maintained. In the process of transitioning from the pen tip retracted state to the pen tip protruding state, the rotating member 5 rotates by a certain angle (for example, 45 degrees), and the friction body 3 rotates by a certain angle (for example, 45 degrees) in conjunction with the rotation of the rotating member 5.

[0060] Next, when the operating part 41 (clip body) is slid forward against the rearward biasing force of the elastic body 7 from the pen tip extended position, the operating part 41 presses the rotating member 5 forward, which in turn presses the rear end of the writing body 6 forward. This disengages the protrusion 52 of the rotating member 5 from the cam teeth 25a, and the protrusion 52 engages with the cam groove 25b, causing the pen tip 61 to retract into the barrel 2 through the front end hole 21a. During this transition from the pen tip extended position to the pen tip retracted position, the rotating member 5 rotates by a certain angle (for example, 45 degrees), and the friction body 3 rotates by a certain angle (for example, 45 degrees) in conjunction with the rotation of the rotating member 5. In other words, the friction body 3c rotates by a certain angle due to the pen tip extension and retraction operation. As a result, the entire friction body 3c is used uniformly, and the proper shape of the friction body 3 can be maintained over a long period of time.

[0061] The thermochromic writing instrument 1 of this embodiment includes a writing body 6 housed inside a barrel 2 so as to be movable in the front-rear direction, thermochromic ink housed inside the writing body 6, a pen tip 61 at the front end of the writing body 6 from which the thermochromic ink can be dispensed, an operating body 4 that is movable in the front-rear direction provided on the side of the barrel 2, a mechanism for extending and retracting the pen tip 61 of the writing body 6 that allows it to extend and retract from the front end hole 21a of the barrel 2 by sliding the operating body 4 forward against the rearward bias of the elastic body 7. The thermochromic writing instrument is equipped with a friction body 3 at the rear end of the barrel 2 that can change the color of the ink by friction, generating frictional heat. The retractable mechanism comprises a cam portion 25 formed inside the barrel 2, a rotating member 5 that engages with the cam portion 25 and abuts against the rear end of the writing body 6, and an operating body 4 that engages with the rotating member 5 in the front-to-back direction. The friction body 3 and the rotating member 5 are engaged to prevent rotation in the rotational direction of the rotating member 5, and the friction body 3 rotates as the rotating member 5 rotates. As a result, the thermochromic writing instrument 1 of this embodiment has uniform wear due to friction of the friction body 3, and can maintain the proper shape of the friction body 3 over a long period of time.

[0062] The thermochromic writing instrument 1 of this embodiment is a thermochromic writing instrument in which a friction body cover 23 is provided at the rear end of the barrel 2 to restrict the rearward movement of the friction body 3. As a result, the thermochromic writing instrument 1 of this embodiment can prevent the friction body 3 from falling out of the barrel 2.

[0063] The thermochromic writing instrument 1 of this embodiment has an opening 23b that penetrates in the front-to-back direction in the center of the friction body cover 23, and the friction body 3 comprises a friction portion 3c that frictions the writing of the thermochromic ink and a flange portion 3a formed in front of the friction portion 3c and projecting radially outward, wherein the friction portion 3c projects rearward from the opening 23b of the friction body cover 23, and the flange portion 3a is locked in the front-to-back direction by a locking wall portion 23c on the inner surface of the friction body cover 23. As a result, the thermochromic writing instrument 1 of this embodiment can rotatably hold the friction body 3 and reliably prevent the friction body 3 from falling out of the barrel 2.

[0064] <Third Embodiment> A third embodiment of the present invention is shown in Figure 19.

[0065] The thermochromic writing instrument 1 of this embodiment is a modified version of the second embodiment, in which the friction element 3 has a different configuration from that of the second embodiment, while the other configurations are the same as those of the second embodiment.

[0066] ·Friction body The friction body 3 comprises a friction portion 31 made of a soft material and a friction portion holder 32 made of a hard material.

[0067] ·Friction part The friction portion 31 is a bottomed cylindrical body with a convex curved top, and its outer diameter decreases towards the rear. An inner hole is opened on the front surface of the friction portion 31.

[0068] • Friction part holder The friction part holder 32 comprises a disc portion 32a, a front core portion 32b integrally formed forward from the axis of the front surface of the disc portion 32a, and a rear core portion 32c integrally formed rearward from the axis of the rear surface of the disc portion 32a.

[0069] An engagement hole 32e is formed in the axis of the friction holder 32, opening forward and extending in the axial direction. The engagement hole 32e is formed in a non-circular cross-section (for example, a cross-shaped cross-section). In addition to a cross-shaped cross-section, other cross-sectional shapes of the engagement hole 32e include, for example, a triangle, a square, a polygon, a star shape, an ellipse, etc.

[0070] The friction body 3 is comprised of a friction portion 31 and a friction portion holder 32. Specifically, the rear core portion 32c of the friction portion holder 32 is inserted into the inner bore of the friction portion 31, and the front end surface of the friction portion 31 is fixed in close contact with the rear surface of the disc portion 32a (for example, by press-fitting, two-color molding, etc.). The friction body 3 as a whole comprises a front core portion 32b, a flange portion 32a, and a friction portion 31 fixed to the rear surface of the flange portion 3a.

[0071] The soft material constituting the friction portion 31 is preferably a rubber elastic material (a rubber or elastomer or other material having rubber elasticity), such as silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin (styrene-ethylene-butylene-styrene copolymer), fluororesin, chloroprene resin, nitrile resin, polyester resin, ethylene propylene diene rubber (EPDM), etc. The rubber elastic material constituting the friction portion 31 is not a highly abrasion elastic material (for example, an eraser), but a low abrasion elastic material that produces almost no wear debris (eraser residue) during friction.

[0072] The hard material constituting the friction part holder 32 only needs to be harder than the friction part 31, and examples include synthetic resins (e.g., polycarbonate, polypropylene, polyethylene, polyacetal, etc.).

[0073] The thermochromic writing instrument 1 of this embodiment includes a writing body 6 housed inside a barrel 2 so as to be movable in the front-rear direction, thermochromic ink housed inside the writing body 6, a pen tip 61 at the front end of the writing body 6 from which the thermochromic ink can be dispensed, an operating body 4 that is movable in the front-rear direction provided on the side of the barrel 2, a mechanism for extending and retracting the pen tip 61 of the writing body 6 that allows it to extend and retract from the front end hole 21a of the barrel 2 by sliding the operating body 4 forward against the rearward bias of the elastic body 7. The thermochromic writing instrument is equipped with a friction body 3 at the rear end of the barrel 2 that can change the color of the ink by friction, generating frictional heat. The retractable mechanism comprises a cam portion 25 formed inside the barrel 2, a rotating member 5 that engages with the cam portion 25 and abuts against the rear end of the writing body 6, and an operating body 4 that engages with the rotating member 5 in the front-to-back direction. The friction body 3 and the rotating member 5 are engaged to prevent rotation in the rotational direction of the rotating member 5, and the friction body 3 rotates as the rotating member 5 rotates. As a result, the thermochromic writing instrument 1 of this embodiment has uniform wear due to friction of the friction body 3, and can maintain the proper shape of the friction body 3 over a long period of time.

[0074] The thermochromic writing instrument 1 of this embodiment is a thermochromic writing instrument in which a friction body cover 23 is provided at the rear end of the barrel 2 to restrict the rearward movement of the friction body 3. As a result, the thermochromic writing instrument 1 of this embodiment can prevent the friction body 3 from falling out of the barrel 2.

[0075] The thermochromic writing instrument 1 of this embodiment comprises a friction body 3 having a friction part 31 that rubs against the writing of the thermochromic ink and a friction part holder 32 that holds the friction part 31, and the friction part holder 32 and the rotating member 5 are engaged in a rotation-preventing engagement in the rotational direction of the rotating member 5. As a result, in the thermochromic writing instrument 1 of this embodiment, the friction part 31 and the rotating member 5 do not directly engage with each other, so the rotation-preventing engagement between the friction body 3 and the rotating member 5 can be made stronger.

[0076] The thermochromic writing instrument 1 of this embodiment has an opening 23b that penetrates in the front-to-back direction in the center of the friction body cover 23, and the friction body 3 comprises a friction portion 31 that frictions the writing of the thermochromic ink and a flange portion 32a formed in front of the friction portion 31 and projecting radially outward, wherein the friction portion 31 protrudes rearward from the opening 23b of the friction body cover 23 and the flange portion 32a is locked in the front-to-back direction by a locking wall portion 23c on the inner surface of the friction body cover 23. As a result, the thermochromic writing instrument 1 of this embodiment can rotatably hold the friction body 3 and reliably prevent the friction body 3 from falling out of the barrel 2. [Explanation of symbols]

[0077] 1. Thermochromic writing instruments 2 shaft cylinder 21 Front axle 21a Front end hole 22 rear axle 23 Friction Cover 23a opening 23b opening 23c Locking wall part 24 slide holes 25 Cam section 25a Cam teeth 25b Cam groove 3 Friction body 31 Friction part 31a Core 31b Convex part 31c recess 31d inner hole 32 Friction part holder 32a Disc section 32b Front core 32c rear core 32d columnar part 32e Engagement hole 3a Tsuba 3b Front core 3c Friction part 3d engagement hole 4 Operating Body 41. Operating section (clip body) 42 Base 43 Shaft section 44 cam teeth 5 Rotating Member 51 Support part 52 protrusion 52a Cam surface 53 Rod-shaped part 53a Engagement part 6 Cursive 61 nib 62 Ink storage tubes 7 projectiles

Claims

1. A writing body is housed inside the barrel so as to be movable in the front-to-back direction, a thermochromic ink is housed inside the writing body, and the front end of the writing body is equipped with a pen tip from which the thermochromic ink can be dispensed. An operating body that can move in the front-rear direction is provided on the side surface of the shaft cylinder, The writing body is biased backward by a spring, and the pen tip of the writing body is made retractable by sliding the operating body forward against the backward bias of the spring, thereby enabling the pen tip of the writing body to extend and retract from the front end hole of the barrel. A thermochromic writing instrument comprising a friction element at the rear end of the barrel capable of thermally changing the color of the ink by friction, which is generated when the ink is rubbed against the writing, The retractable mechanism comprises a cam portion formed inside the barrel, a rotating member that engages with the cam portion and abuts against the rear end of the writing body, and an operating body that engages with the rotating member in a front-to-back manner. A thermochromic writing instrument characterized in that the friction body and the rotating member are engaged to prevent rotation in the rotational direction of the rotating member, and the friction body rotates as the rotating member rotates.

2. The thermochromic writing instrument according to claim 1, wherein a friction body cover is provided at the rear end of the barrel for restricting the rearward movement of the friction body.

3. The thermochromic writing instrument according to claim 2, wherein the friction body comprises a friction portion that frictionally rubs against the writing of the thermochromic ink and a friction portion holder that holds the friction portion, and the friction portion holder and the rotating member are engaged to prevent rotation in the rotational direction of the rotating member.

4. Multiple friction portions are provided at equal intervals on the outer peripheral edge of the rear end of the friction portion holder. The friction body cover is provided so as to cover the friction body, An opening is provided at the outer peripheral edge of the rear end of the friction body cover, allowing the friction portion of the friction body to be exposed. The friction body rotates in conjunction with the extension and retraction of the pen tip. When the pen tip is fully submerged, each of the friction parts is covered by the friction body cover. The thermochromic writing instrument according to claim 3, wherein the friction portion is exposed from the opening when the pen tip is extended.

5. An opening is provided in the center of the friction body cover that penetrates in the front-to-back direction. The friction body comprises a friction portion that rubs against the writing of the thermochromic ink, and a flange portion formed in front of the friction portion and projecting radially outward. The thermochromic writing instrument according to claim 2, wherein the friction portion protrudes rearward from the opening of the friction body cover, and the flange portion is locked back and forth by the locking wall portion on the inner surface of the friction body cover.

6. The thermochromic writing instrument according to claim 1 or 5, wherein the friction body comprises a friction portion that frictionally rubs against the writing of the thermochromic ink and a friction portion holder that holds the friction portion, and the friction portion holder and the rotating member are engaged to prevent rotation in the rotational direction of the rotating member.

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