Thermochromic writing implements

Abstract

To provide a thermochromic writing instrument capable of performing stable and appropriate friction without causing a friction body to wobble in friction and installing the friction body by a desired projection length.SOLUTION: The thermochromic writing instrument includes a friction body at a rear end of a barrel and a head crown installed by screwing; a head crown installation part projecting backward is provided at the rear end of the barrel, and a male screw part, an abutting part abutting on an inner surface of the head crown when screwing the head crown, and a notch are formed in the head crown installation part; a friction body installation hole opened backward is provided at a rear end of the head crown installation part; a female screw part and a guide part on which the abutting part abuts when screwing the head crown are formed on an inner face of the head crown; a load is applied onto the abutting part from the guide part when screwing the head crown to be set so as to be reduced in an inner diameter of the friction body installation hole.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a thermochromic writing instrument, and more particularly to a thermochromic writing instrument equipped with a friction body capable of thermally discoloring a mark made of thermochromic ink by rubbing the mark made of the thermochromic ink with the frictional heat generated during the rubbing. [Background technology]

[0002] Patent Document 1 discloses a thermochromic writing instrument that contains thermochromic ink inside a barrel, is configured so that the thermochromic ink can be ejected from a pen tip at the front end of the barrel, and is equipped with a friction body at the rear end of the barrel that can rub the handwriting of the thermochromic ink and thermochromically change the color of the thermochromic ink with the frictional heat generated in the process.

[0003] The configuration of the first embodiment described in Patent Document 1 includes a barrel, a crown that is detachably attached to the rear end of the barrel by screwing, a friction body that is detachably attached to the rear end of the crown by screwing, and a spare friction body housed inside the barrel and the crown, wherein the barrel is provided with a first crown attachment portion that protrudes rearward, an outer surface of the first crown attachment portion has a first male thread portion, the crown is provided with a barrel attachment hole that opens forward, an inner surface of the barrel attachment hole has a first female thread portion that can be screwed into the first male thread portion, the crown is provided with a friction body attachment hole that opens rearward, and an inner surface of the friction body attachment hole has a second female thread portion, the friction body and the spare friction body are provided with a second crown attachment portion that protrudes forward, an outer surface of the second crown attachment portion has a second male thread portion, the second crown attachment portion can be attached to the friction body attachment hole by screwing, and the friction body is replaceable with the spare friction body.

[0004] According to the thermochromic writing instrument described in the first embodiment, the friction body does not wobble during friction, providing stable and appropriate friction, and the friction body attached to the crown can be easily replaced with a spare friction body, so that the friction performance of the thermochromic writing instrument can be maintained for a long period of time, making it possible to provide a thermochromic writing instrument with high commercial value.

[0005] The configuration of the second embodiment described in Patent Document 1 includes a barrel, a crown that is detachably attached to the rear end of the barrel by screwing, and a friction body, the barrel is provided with a first crown attachment portion that protrudes rearward, the outer surface of the first crown attachment portion has a first male thread portion, the crown is provided with a barrel attachment hole that opens forward, the inner surface of the barrel attachment hole has a first female thread portion that can be screwed into the first male thread portion, the crown is provided with a reduced diameter portion that protrudes radially inward at its rear end, the friction body is provided with a friction portion and a spare friction portion at both ends, the friction body is provided with a flange portion that protrudes radially outward at the axial center, the flange portion is clamped by the rear end of the first crown attachment portion and the reduced diameter portion, the friction body is prevented from coming off by the barrel, and the friction portion and the spare friction portion can be attached in a reversed front-to-back manner.

[0006] According to the thermochromic writing instrument described in the second embodiment, the friction body does not wobble during friction, providing stable and appropriate friction, and the friction body attached to the crown can be easily replaced from the friction section to the spare friction section, so that the friction performance of the thermochromic writing instrument can be maintained for a long period of time, making it possible to provide a thermochromic writing instrument with high commercial value.

[0007] [Patent Document 1] JP 2020-69743 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0008] In the technology disclosed in the first embodiment described in Patent Document 1, the outer diameter of the friction body is small compared to the outer diameters of the barrel and the crown, which may make it difficult to apply an appropriate tightening torque for screwing. As a result, the friction body may wobble or loosen during friction, which may prevent stable and appropriate friction.

[0009] On the other hand, in the technology disclosed in the second embodiment described in Patent Document 1, the friction body is attached by gripping the crown, which has a larger outer diameter than the friction body, and screwing it in, so that it is possible to apply an appropriate tightening torque. However, since the amount (length) that the friction body protrudes forward is determined by the position of the flange, there is a problem that the friction body cannot be attached with a desired protruding amount.

[0010] The present invention has been made in consideration of the above findings, and aims to provide a thermochromic writing instrument that can provide stable and appropriate friction without wobbling of the friction body during friction, and that can be attached with a desired protruding amount. In the present invention, "rear" refers to the side where the friction body is attached, and "front" refers to the opposite side. [Means for solving the problem]

[0011] The present invention comprises a barrel configured to accommodate thermochromic ink therein and to be able to eject the thermochromic ink from a pen tip at the front end, a friction body at the rear end of the barrel that rubs the handwriting of the thermochromic ink and is able to thermochromic the handwriting of the thermochromic ink with the frictional heat generated at the time, and a crown that is screwed onto the rear end of the barrel, the rear end of the barrel being provided with a crown attachment part that protrudes rearward, the rear end of the crown attachment part being provided with a friction body attachment hole that opens rearward, at least a part of the outer periphery of the crown attachment part being provided with a male thread part, and a contact portion that contacts a portion of the inner surface of the crown as the crown mounting portion is screwed into the crown, a notch is formed in a portion of the crown mounting portion so that the inner diameter of the friction body mounting hole decreases when a load is received at the contact portion, and a female thread portion that can be screwed into the male thread portion and a guide portion with which the contact portion contacts as the crown and the crown mounting portion are screwed together are formed on a portion of the inner surface of the crown,

[0012] According to the present invention, when the crown and the crown mounting part are screwed together, the abutting part of the crown mounting part receives a load from the guide part of the crown. In this case, the presence of the notch in the crown mounting part reduces the inner diameter of the friction body mounting hole, and the crown and the crown mounting part cooperate to hold the friction body without rattling (play). This allows stable and appropriate friction without the friction body wobbling during friction, and the friction body can be mounted with a desired protrusion amount.

[0013] In addition, it is preferable that the abutment portion is provided at the rear end of the crown mounting portion, whereby the distance between the abutment portion and the base of the notch is increased, and the friction body mounting hole can be easily reduced in diameter, so that the friction body can be more reliably gripped.

[0014] In addition, it is preferable that a plurality of the notches are arranged at equal intervals in the circumferential direction of the crown mounting part, and each of the plurality of notches is a slit extending in the axial direction of the crown mounting part. With this, the inner diameter of the friction body mounting hole can be reduced in a well-balanced manner in the circumferential direction.

[0015] Moreover, the contact portion is preferably tapered toward the rear end, and the guide portion is also preferably tapered toward the rear end. The contact portion preferably has, for example, a truncated cone surface. In this case, the guide portion is preferably a corresponding concave truncated cone surface. Alternatively, the contact portion preferably has a convex curved surface that is rotationally symmetric about an axis. In this case, the guide portion is preferably a concave curved surface or a concave truncated cone surface that is rotationally symmetric about an axis and has a curvature that is gentler than the curvature of the convex curved surface.

[0016] It is also preferable that an inward locking portion is formed on the inner peripheral surface of the friction body mounting hole, and an outward locking portion is formed circumferentially on the outer peripheral surface of the friction body. In this case, the friction body mounting hole can hold the friction body more reliably, so that the friction body does not wobble during friction and stable and appropriate friction can be achieved. Furthermore, by changing the position where the inward locking portion and the outward locking portion are locked, the friction body can be reliably held at a desired position. In other words, the friction body can be reliably mounted with a desired protrusion amount.

[0017] The present invention also covers a friction tool equipped with a friction body without a pen tip. That is, the present invention includes a barrel, a friction body at the rear end of the barrel that rubs a mark of thermochromic ink and can thermally discolor the mark of thermochromic ink with the frictional heat generated at the time, and a crown that is screwed and attached to the rear end of the barrel, the rear end of the barrel is provided with a crown attachment part that protrudes rearward, the rear end of the crown attachment part is provided with a friction body attachment hole that opens rearward, at least a part of the outer periphery of the crown attachment part is provided with a male screw part, and a part of the inner surface of the crown is provided with a male screw part that is screwed with the crown and the crown attachment part. a notch is formed in a portion of the crown mounting portion so that the inner diameter of the friction body mounting hole is reduced when a load is received at the abutment portion; a female thread portion that can be screwed into the male thread portion and a guide portion with which the abutment portion abuts as the crown and the crown mounting portion are screwed together are formed in a portion of the inner surface of the crown; and the abutment portion receives the load from the guide portion as the crown and the crown mounting portion are screwed together. Effect of the Invention

[0018] The present invention can provide a thermochromic writing implement in which the friction body does not wobble during friction, providing stable and appropriate friction, and in which the friction body can be attached with a desired amount of protrusion. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a front view showing a thermochromic writing instrument according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged perspective view of a main portion showing a crown mounting portion of the barrel of FIG. 1. [Diagram 3] FIG. 2 is an exploded view showing a state in which the friction body in FIG. 1 is replaced. [Figure 4] FIG. 2 is an enlarged longitudinal sectional view of a main part showing a state in which the friction body in FIG. 1 is attached. [Diagram 5] 5 is an enlarged longitudinal sectional view of a main part showing a state in which the friction body protrusion amount in FIG. 4 is changed. [Figure 6] FIG. 11 is a perspective view showing a friction body according to a second embodiment of the present invention. [Figure 7] FIG. 11 is an enlarged perspective view of a main portion showing a crown mounting portion of a barrel according to a second embodiment of the present invention. [Figure 8] FIG. 11 is an enlarged perspective view of a main portion showing a crown mounting portion of a barrel according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Three embodiments of the present invention will now be described with reference to the drawings.

[0021] First Embodiment 1 to 5 show a first embodiment of the present invention. FIG. 1 is a front view of a thermochromic writing instrument 1 in the first embodiment of the present invention, showing a state in which the pen tip (writing body) does not protrude. FIG. 2 is an enlarged perspective view of a main part showing a crown mounting part 31 of a barrel 3 in this embodiment. FIG. 3 is an exploded view showing a state when replacing a friction body 4 in this embodiment. FIG. 4 is an enlarged vertical cross-sectional view of a main part showing a state in which the friction body is mounted in this embodiment. FIG. 5 is an enlarged vertical cross-sectional view of a main part showing a state in which the friction body 4 is mounted with a different protruding amount from that in FIG. 4.

[0022] The thermochromic writing instrument 1 of this embodiment is a multi-core retractable writing instrument, which has a slide operating part on the outer surface of the side wall of the barrel 3, and is configured to cause the writing tip of the writing body to appear and retract from the opening at the tip of the barrel 3 by sliding the slide operating part or the clip part as the operating part.

[0023] The writing body is stored in the barrel 3, and a writing instrument can be configured in which the writing tip of the writing body appears and retracts from the opening at the tip of the barrel 3 by operating the retraction mechanism. A plurality of writing bodies (specifically, three) are stored in the barrel 3 so as to be movable in the front-rear direction, and each writing body is urged backward by a resilient body (specifically, a compression coil spring).

[0024] Other examples of the retractable mechanism include a rear-end knock type, in which the pen tip protrudes and retracts by pressing forward on the operating part at the rear end of the barrel; a side knock type, in which the pen tip protrudes and retracts by pressing radially inward on the operating part that protrudes from the outer surface of the side wall of the barrel; and a rotation type, in which the pen tip protrudes and retracts by rotating the operating part at the rear of the barrel.

[0025] ·Cursive The writing body comprises a pen tip, an ink reservoir tube into whose front end opening the pen tip is press-fitted, thermochromic ink filled in the ink reservoir tube, and a follower (e.g., a high-viscosity fluid) filled in the rear end of the thermochromic ink and moving forward as the thermochromic ink is consumed. Of the writing bodies applicable to the thermochromic writing instrument 1 of this embodiment, one or more writing bodies containing a thermochromic ink composition are contained in the barrel 3.

[0026] The pen tip may be, for example, composed of only 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 having an air hole that allows ventilation between the ink reservoir tube and the outside is attached to the rear end opening of the ink reservoir tube. A spring that presses the ball at the front end forward is housed inside the pen tip. The spring is a compression coil spring with a rod portion at its front end, and the front end of the rod portion is in contact with the rear surface of the ball. When not writing, the forward bias of the spring brings the ball into close contact with the inner surface of the inward-facing front end edge of the front end of the ballpoint pen tip, preventing ink leakage from the front end of the pen tip and ink evaporation.

[0027] Thermochromic ink In the present invention, the thermochromic ink is preferably a reversible thermochromic ink. The reversible thermochromic ink may be of various types, such as a heat-discoloring type that is decolorized by heating from a colored state, a color memory-retaining type that alternately retains a colored state or a decolored state in a specific temperature range, or a heat-coloring type that is colored by heating from a decolored state and returns to the decolored state by cooling from the colored state, either alone or in combination.

[0028] The coloring material contained in the reversible thermochromic ink is preferably a reversible thermochromic microencapsulated pigment in which a reversible thermochromic composition containing at least the three essential components, namely (i) an electron-donating color-forming organic compound, (ii) an electron-accepting compound, and (iii) a reaction medium that determines the temperature at which the color-forming reaction between the two occurs, is encapsulated in a microcapsule.

[0029] ·Shaft cylinder As shown in Fig. 1, the thermochromic writing instrument 1 of this embodiment includes a barrel 3 consisting of a tapered cylindrical front barrel 3a and a cylindrical rear barrel 3b attached to the rear end of the front barrel 3a by screwing or press-fitting. An opening through which the pen tip of the writing tool can protrude is provided in the axial direction at the front end of the front barrel 3a. The front barrel 3a and the rear barrel 3b are made of synthetic resin (e.g., polycarbonate) or metal.

[0030] 1, the rear side wall of the rear axle 3b is provided with, for example, three (selectable from two to six) elongated window holes 37 extending in the front-rear direction and extending radially therethrough. The three window holes 37 are formed, for example, at equal intervals in the circumferential direction.

[0031] 2 or 3, a crown mounting part 31 protruding rearward is provided at the rear end of the barrel 3, and the crown 2 described below is detachably attached by screwing to the crown mounting part 31. A friction body mounting hole 34 opening rearward is provided at the rear end of the crown mounting part 31.

[0032] At least a portion of the outer periphery of the crown attachment portion 31 has a male thread portion 32 and an abutment portion 33. The abutment portion 33 abuts against a portion of the inner surface of the crown 2 (the guide portion 23) as the crown 2 and the crown attachment portion 31 of the barrel 3 are screwed together, and receives a load from the guide portion 23 of the crown 2.

[0033] The contact portion 33 is preferably provided at the rear end of the crown mounting portion 31. This increases the distance between the contact portion 33 and the base of the notch 35, making it easier to reduce the diameter of the friction body mounting hole 34, and allowing the friction body 4 to be gripped more reliably.

[0034] In addition, it is preferable that the abutment portion 33 is tapered toward the rear end. This allows the abutment portion 33 to be inserted into the guide portion 23 without getting caught on the inner surface of the crown. In addition, the abutment portion 33 abuts against the guide portion 23 of the crown 2 as the crown 2 and the crown mounting portion 31 of the barrel 3 are screwed together, and can smoothly receive a load from the guide portion 23 of the crown 2, allowing the inner diameter of the friction body mounting hole 34 to be easily reduced.

[0035] Moreover, it is more preferable that the abutment portion 33 has a truncated cone surface. In this case, it is preferable that the guide portion 23 is a corresponding concave truncated cone surface. Alternatively, the abutment portion 33 may have a convex curved surface that is rotationally symmetric about the axis. In this case, it is preferable that the guide portion 23 is a concave curved surface or a concave truncated cone surface that is rotationally symmetric about the axis and has a curvature that is gentler than the curvature of the convex curved surface. According to this, the abutment portion 33 of the crown mounting portion 31 can receive a load in a circumferentially balanced manner, and as a result, the inner diameter of the friction body mounting hole 34 can be reduced in a circumferentially balanced manner, and the friction body 4 can be constantly gripped without rattling (play).

[0036] A notch 35 is formed in a part of the crown mounting part 31. As a result, when a load is received at the abutment part 33 as the crown 2 and the crown mounting part 31 of the barrel 3 are screwed together, the inner diameter of the friction body mounting hole 34 is reduced. A plurality of notches 35 are arranged at equal intervals in the circumferential direction of the crown mounting part 31, and each of the plurality of notches 35 is preferably a slit extending in the axial direction of the crown mounting part 31. This allows the inner diameter of the friction body mounting hole 34 to be reduced in a well-balanced manner in the circumferential direction.

[0037] Moreover, it is preferable that the slit opens at the rear end and penetrates in the radial direction, so that the slit can be easily deflected (reduced in diameter in the radial direction) by the load received by the abutting portion 33.

[0038] In this embodiment, the male thread portion 32 and the position where the slit is formed do not overlap in the axial direction. This prevents the male thread portion 32 from deforming in the radial direction, so that screwing can be performed reliably. Also, since the wall thickness of the abutment portion 33 where the slit is formed does not increase, the slit can be easily deflected (reduced in diameter in the radial direction) by the load received by the abutment portion 33.

[0039] On the other hand, the positions where the male thread portion 32 and the slit are formed may overlap in the axial direction. This allows the axial length of the parts (the axial length of the crown 2 and the crown mounting portion 31) to be shortened, thereby increasing the degree of freedom in the shape of the writing instrument. In addition, since the axial length of the slit can be lengthened, the slit can be easily deflected (reduced in diameter in the radial direction) by the load received by the abutment portion 33.

[0040] The inner surface of the friction body mounting hole 34 is provided with a gripping portion that grips a gripped portion 41 of the friction body 4, which will be described later. In this embodiment, the gripping portion has a cylindrical inner surface shape. When the abutment portion 33 receives a load from the guide portion 23 as the crown 2 and the crown mounting portion 31 of the barrel 3 are screwed together, the inner diameter of the gripping portion decreases and grips the gripped portion 41 of the friction body 4, which will be described later, so that the friction body 4 is in an attached state.

[0041] ·Head crown 3 to 5, the thermochromic writing instrument 1 of this embodiment has a crown 2 detachably attached by screwing to the rear end of the barrel 3. The crown 2 has a barrel attachment hole 21 that opens to the front and an insertion portion 24 that opens to the rear.

[0042] A part of the inner surface of the shaft tube mounting hole 21 has a female threaded portion 22 that can be screwed into the male threaded portion 32, and a guide portion 23 with which an abutment portion 33 abuts as the crown 2 is screwed into the crown mounting portion 31. The guide portion 23 is preferably provided behind the shaft tube mounting hole 21, i.e., in front of the insertion portion 24.

[0043] Also, it is preferable that the guide portion 23 is tapered toward the rear end. As described above, this allows the abutment portion 33 to be inserted into the guide portion 23 without getting caught on the inner surface of the crown. Also, the abutment portion 33 abuts against the guide portion 23 of the crown 2 as the crown 2 and the crown mounting portion 31 of the barrel 3 are screwed together, and can smoothly receive a load from the guide portion 23 of the crown 2, allowing the inner diameter of the friction body mounting hole 34 to be easily reduced.

[0044] Also, it is more preferable that the guide portion 23 has a concave truncated cone surface. In this case, it is preferable that the contact portion 33 is a corresponding convex truncated cone surface or a convex curved surface that is rotationally symmetric about the axis. Alternatively, it is preferable that the guide portion 23 has a concave curved surface that is rotationally symmetric about the axis. In this case, it is preferable that the contact portion 33 is a convex curved surface that is rotationally symmetric about the axis and has a curvature smaller than that of the concave curved surface. According to this, the contact portion 33 of the crown mounting portion 31 can receive a load in a circumferentially balanced manner, and as a result, the inner diameter of the friction body mounting hole 34 can be reduced in a circumferentially balanced manner, and the friction body 4 can be constantly gripped in a manner without rattling (play).

[0045] A rotation operation part consisting of a two-sided width portion or a knurled portion may be formed on the outer surface of the crown 2. By rotating the rotation operation part, the shaft tube 3 and the crown 2 can be easily screwed together or released, making it possible to easily attach and detach the shaft tube 3 and the crown 2. Examples of the rotation operation part include a two-sided width portion such as a hexagonal or octagonal portion that can be hung with a wrench, a knurled portion, or other outward protrusions.

[0046] ·Friction body The thermochromic writing instrument 1 includes a friction body 4. In this embodiment, the friction body 4 preferably has thermochromic ink built therein and is provided at the rear end of the writing instrument from which the thermochromic ink can be ejected.

[0047] In this embodiment, the elastic material constituting the friction body 4 is preferably a synthetic resin (rubber, elastomer) having elasticity, and examples thereof include silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin (styrene-ethylene-butylene-styrene copolymer), fluorine-based resin, chloroprene resin, nitrile resin, polyester-based resin, ethylene propylene diene rubber (EPDM), a mixture of two or more kinds of rubber elastic materials, and a mixture of a rubber elastic material and a synthetic resin. The synthetic resin having elasticity constituting the friction body 4 is not a highly abrasive elastic material (e.g., eraser, etc.), but a low-abrasive elastic material that hardly generates abrasion debris (eraser debris) during friction. The friction body 4 can be combined with a writing implement and a friction implement that is a separate member of any shape to obtain a writing implement set, but by providing the friction body 4 with the writing implement, the writing implement has excellent portability.

[0048] The friction body 4 may be formed from a mixture of polypropylene resin and a styrene-based thermoplastic elastomer, or a mixture of polypropylene resin and a polypropylene-based thermoplastic elastomer. The blending ratio of the mixture is 1:1 to 1:4 by weight, and the material does not contain abrasives, plasticizers, or fillers, and has a durometer hardness A of 70° to 100° as specified in JIS K6251. The material is formed from a low-wear elastic material that does not contain plasticizers and has a pencil line erasability (erasability) of 70% or less as specified in JIS S 6050-2002. As a result, the friction body 4 is effective because it is less likely to produce eraser shavings when rubbed and has excellent thermal discoloration.

[0049] The friction body 4 is made of a low-wear elastic material that hardly produces any wear debris (eraser debris) during friction, but it may gradually wear down or become damaged depending on the type or condition of the rubbing surface or the rubbing method. A worn or damaged friction body 4 cannot provide appropriate friction, and it may become difficult to rub the thermochromic ink mark and thermally discolor the thermochromic ink mark with the frictional heat generated during the friction.

[0050] Furthermore, if there is handwriting written with a pencil or the like on the friction surface, or if the friction surface is dirty, there is a possibility that pencil lead residue or dirt will be transferred to the friction body 4, thereby soiling the friction body 4. If the soiled friction body 4 is rubbed against another paper surface, the dirt or the like that has adhered to the friction body 4 may be transferred to the paper surface, thereby soiling the paper surface.

[0051] When the friction body 4 becomes worn, damaged, or soiled, it is possible to provide appropriate friction again by replacing the worn, damaged, or soiled friction body 4 with a new friction body.

[0052] 3 to 5, the friction body 4 of this embodiment will be described below. The friction body 4 has a cylindrical gripped portion 41 at the center in the axial direction. The friction body 4 also has a first friction portion 4a and a second friction portion 4b adjacent to the gripped portion 41 at both ends.

[0053] As shown in Fig. 3, it is preferable that the gripped portion 41 does not have a step or a flange. In other words, it is sufficient if the gripped portion 41 has a shape that does not get caught when the friction body 4 is inserted into the friction body mounting hole. This allows the position for gripping the friction body 4 to be determined arbitrarily on the gripped portion 41. In other words, the friction body 4 can be mounted with a desired protruding length.

[0054] In addition, it is preferable that the first frictional portion 4a and the second frictional portion 4b have a symmetrical shape from front to back. This allows the first frictional portion 4a and the second frictional portion 4b to be attached by being reversed from front to back, and the handwriting portion that is hidden by the frictional portion 4a during friction is narrowed, improving the visibility of the handwriting and making it easier to erase.

[0055] In order to obtain the same friction performance before and after replacement of the friction body 4, it is preferable that the friction part 4a and the spare friction part 4b have the same shape. This makes it possible to obtain the same constant friction performance as before replacement even after the first friction part 4a is replaced with the second friction part 4b due to wear or the like, and to maintain stable friction performance.

[0056] In addition, when the friction range is changed by changing the shape of the friction part, it is preferable that the first friction part 4a and the second friction part 4b have different shapes, so that one friction body can rub both a wide range and a narrow range.

[0057] The friction body 4 may have an air flow path in the axial direction. With this, even if an infant accidentally swallows the friction body 4, the air flow path of the friction body 4 is breathable, and the airway can be secured, thereby preventing choking accidents.

[0058] In the thermochromic writing instrument 1 of this embodiment, a rotation operation part consisting of a two-sided width part or a knurled part may be formed on the outer surfaces of the first friction part 4a and the second friction part 4b. By gripping the rotation operation part and operating the friction body 4, it is possible to more easily adjust the projection length of the friction body 4 from the crown 2. Examples of the rotation operation part include a two-sided width part such as a hexagonal or octagonal part that can be hung with a wrench, or a knurled part.

[0059] The thermochromic writing instrument 1 having the above-mentioned configuration operates as follows.

[0060] Before the friction body is attached, the rear part of the thermochromic writing instrument 1 is in a disassembled state as shown in Fig. 3. In the state shown in Fig. 3, the inner diameter of the friction body attachment hole 34 is the same as or slightly larger than the outer diameter of the gripped part 41 of the friction body 4. Therefore, the friction body 4 can be loosely fitted or inserted into the friction body attachment hole 34.

[0061] Thereafter, as the crown 2 is attached by screwing the female threaded portion 22 provided in the crown 2 into the male threaded portion 32 provided on the crown attachment portion 31, the guide portion 23 provided in the crown 2 and the abutment portion 33 provided on the crown attachment portion 31 come into abutment, and the abutment portion 33 bears the load.

[0062] The load acts on the notch 35 provided in the crown mounting portion 31, reducing the inner diameter of the friction body mounting hole 34. As a result, the inner diameter of the friction body mounting hole 34 becomes smaller than the outer diameter of the gripped portion 41 of the friction body 4, so that the friction body 4 can be gripped in the friction body mounting hole 34 without any rattling (play) as shown in FIG.

[0063] On the other hand, when removing the friction body 4 or changing the length of the friction body 4 protruding from the crown 2, the screwing of the crown 2 is loosened from the state shown in Fig. 4. In this case, the load that the abutting portion 33 received from the guide surface is reduced, and the inner diameter of the friction body mounting hole 34 is again the same as or slightly larger than the outer diameter of the gripped portion 41 of the friction body 4. Therefore, the friction body 4 is loosely fitted or loosely inserted in the friction body mounting hole 34, and the friction body 4 can be moved axially to the state shown in Fig. 5, in which the protruding length is longer than that of Fig. 4. Alternatively, the friction body 4 can be made detachable and freely attached. The friction body mounting structure of the present invention can also be applied as an eraser mounting structure for an eraser mounted on a mechanical pencil or the like, or for an eraser mounted only on an eraser.

[0064] As described above, according to the thermochromic writing instrument 1 of this embodiment, the friction body 4 does not wobble during friction, providing stable and appropriate friction, and further, a thermochromic writing instrument 1 can be provided in which the friction body 4 can be attached with a desired amount of protrusion.

[0065] <Second embodiment> A second embodiment of the present invention is shown in Fig. 6 or 7. This is a modification of the first embodiment, and differs from the first embodiment in that an inward locking portion 36 is formed on the inner peripheral surface of the friction body mounting hole 34, and an outward locking portion 42 is formed circumferentially on the outer peripheral surface of the friction body 4. The other configurations and effects are the same as those of the first embodiment, so a description thereof will be omitted.

[0066] In the second embodiment of the present invention, an inward locking portion 36 is formed on the inner circumferential surface of the friction body mounting hole 34. The inward locking portion 36 is a plurality of inward protrusions discretely arranged on the inner circumferential surface of the friction body mounting hole 34 as shown in Fig. 7. The inward locking portions 36 are preferably arranged at equal intervals between the notches 35 (slits) of which a plurality are arranged in the crown mounting portion 31.

[0067] In the second embodiment of the present invention, a circumferential outward locking portion 42 is formed on the outer circumferential surface of the friction body 4, i.e., on the gripped portion 41, as shown in Fig. 6. The outward locking portion 42 is an annular outward protrusion, and eight of the outward locking portions 42 are formed continuously at equal intervals in the axial direction. It is preferable that at least two of the outward locking portions 42 are formed.

[0068] As a result, the friction body mounting hole 34 can hold the friction body 4 more securely, so that the friction body 4 does not wobble during friction, and more stable and appropriate friction can be achieved. Also, by changing the position at which the inward locking portion 36 and the outward locking portion 42 are locked, the friction body 4 can be securely held at a desired position. In other words, after the friction body is mounted, the friction body 4 is prevented from shifting in the axial direction, and the desired protrusion amount can be easily maintained.

[0069] In this embodiment, eight outward locking portions 42 are formed in succession at equal intervals in the axial direction. This makes it easy to reattach the friction body 4 in the same position even after removing the friction body 4, in other words, to hold the friction body 4 in a desired position.

[0070] <Third embodiment> 8 shows a third embodiment of the present invention. This is a modification of the second embodiment, and differs from the second embodiment in that a circumferential inward locking portion 36 is formed on the inner circumferential surface of the friction body mounting hole 34. Other configurations and effects are the same as those of the first and second embodiments, so a description thereof will be omitted.

[0071] In the third embodiment of the present invention, two circumferential inward locking portions 36 are formed on the inner circumferential surface of the friction body mounting hole 34. The inward locking portions 36 are inward protrusions that are continuously arranged circumferentially on the inner circumferential surface of the friction body mounting hole 34 excluding the slit portions, as shown in Fig. 8. It is sufficient that at least one inward protrusion is formed, but it is more preferable that a plurality of inward protrusions are formed continuously at equal intervals in the axial direction, as shown in Fig. 8.

[0072] Furthermore, when the inward locking portions of the barrel of this embodiment are formed in succession at equal intervals in the axial direction, it is preferable that the distance between each of the inward locking portions 36 of the barrel (axial arrangement pitch) is equal to the distance between each of the outward locking portions 42 of the friction body 4 shown in FIG. 6 (axial arrangement pitch).

[0073] As a result, the friction body mounting hole 34 can grip the friction body 4 with a higher gripping force, so that the friction body 4 does not wobble during friction, and more stable and appropriate friction can be achieved. In addition, after the friction body is mounted, the friction body 4 is more prevented from shifting in the axial direction, and the desired protrusion amount can be easily maintained.

[0074] The present invention also covers a friction tool equipped with a friction body without a pen tip. The effects are the same as those of the first to third embodiments, and therefore the description thereof will be omitted. That is, the present invention comprises a barrel, a friction body at the rear end of the barrel that rubs handwriting of thermochromic ink and can thermally discolor the handwriting of thermochromic ink with the frictional heat generated at the time, and a crown that is screwed and attached to the rear end of the barrel, and a crown attachment part that protrudes rearward is provided at the rear end of the crown attachment part, a friction body attachment hole that opens rearward is provided at at least a part of the outer periphery of the crown attachment part, and a male screw part is provided at at least a part of the inner surface of the crown as the crown and the crown attachment part are screwed together. a notch is formed in a portion of the crown mounting portion so that the inner diameter of the friction body mounting hole is reduced when a load is received at the abutment portion; a female thread portion that can be screwed into the male thread portion and a guide portion with which the abutment portion abuts as the crown and the crown mounting portion are screwed together are formed in a portion of the inner surface of the crown; and the abutment portion receives the load from the guide portion as the crown and the crown mounting portion are screwed together. [Explanation of symbols]

[0075] 1 Thermochromic writing implements 2 crown 21 Shaft cylinder mounting hole 22 Female thread 23 Information Department 24 Insertion part 3 shaft cylinder 3a front axle 3b rear axle 31 Crown attachment part 32 Male thread 33 Contact part 34 Friction body mounting hole 35 Notch 36 Inward locking part 37 Window Hole 4 Friction body 4a 1st friction part 4b 2nd friction part 41 Grasped part 42 Outward locking part

Claims

1. A barrel that contains thermochromic ink inside and is configured so that the thermochromic ink can be ejected from a pen tip at a front end thereof; a friction body disposed at the rear end of the barrel, capable of rubbing the mark of the thermochromic ink and thermally discoloring the mark of the thermochromic ink with frictional heat generated at the time; a crown attached to the rear end of the barrel by screwing; A crown mounting portion protruding rearward is provided at the rear end of the barrel, A friction body mounting hole opening rearward is provided at the rear end of the crown mounting portion, At least a part of the outer periphery of the crown mounting part is formed with a male thread part and an abutment part that abuts against a part of the inner surface of the crown as the crown and the crown mounting part are screwed together, A notch is formed in a part of the crown mounting portion, and an inner diameter of the friction body mounting hole is reduced when a load is received at the abutment portion, A female threaded portion that can be screwed into the male threaded portion and a guide portion against which the abutment portion abuts as the crown and the crown mounting portion are screwed together are formed on a part of the inner surface of the crown, The abutment portion receives the load from the guide portion as the crown and the crown mounting portion are screwed together, The contact portion is tapered toward the rear end, and the guide portion is also tapered toward the rear end, The abutment portion has a truncated conical surface.

2. The abutment portion is provided at the rear end of the crown mounting portion.

2. The thermochromic writing instrument according to claim 1 .

3. The notches are arranged at equal intervals in a circumferential direction of the crown mounting portion, Each of the plurality of notches is a slit extending in the axial direction of the crown mounting portion.

3. The thermochromic writing instrument according to claim 1 or 2.

4. An inward locking portion is formed on the inner circumferential surface of the friction body mounting hole, The friction body has an outer peripheral surface on which an outward engaging portion is formed.

4. A thermochromic writing instrument according to claim 1.

5. A shaft cylinder, a friction body disposed at the rear end of the barrel, capable of rubbing the thermochromic ink mark and thermally discoloring the thermochromic ink mark with the frictional heat generated at the time; a crown attached to the rear end of the barrel by screwing; A crown mounting portion protruding rearward is provided at the rear end of the barrel, A friction body mounting hole opening rearward is provided at the rear end of the crown mounting portion, At least a part of the outer periphery of the crown mounting part is formed with a male thread part and an abutment part that abuts against a part of the inner surface of the crown as the crown and the crown mounting part are screwed together, A notch is formed in a part of the crown mounting portion, and an inner diameter of the friction body mounting hole is reduced when a load is applied to the abutment portion, a female thread portion that can be screwed into the male thread portion, and a guide portion with which the abutment portion abuts as the crown and the crown mounting portion are screwed together, The abutment portion receives the load from the guide portion as the crown and the crown mounting portion are screwed together, The contact portion is tapered toward the rear end, and the guide portion is also tapered toward the rear end, The abutment portion is a friction tool having a truncated cone surface.

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