Thermochromic writing instruments and friction tools

Abstract

To provide a thermochromic writing instrument and friction tool in which the friction body is not susceptible to contamination by external factors, there is no risk of losing parts when using the friction body, and in addition, there is no risk of the friction body unexpectedly falling out of the cylinder when it wears down. [Solution] A thermochromic writing instrument 1 comprises a cylindrical body 2 which is a barrel or cap having an opening 21 at one end, a thermochromic ink that can be decolorized or discolored by heating, and a friction tool 3 that can be detachably attached to the opening 21 of the cylindrical body 2, wherein the friction tool 3 comprises a friction body 4 that rubs against the writing made by the thermochromic ink to decolorize or discolor the writing, and a lid body 5 that can be detachably attached to the opening 21 of the cylindrical body 2, the friction body 4 and the lid body 5 are connected, and when the lid body 5 of the friction tool 3 is attached to the opening 21 of the cylindrical body 2, the friction body 4 is located inside the opening 21 and the friction body 4 is not in contact with the inner surface of the opening 21.

Description

Technical Field

[0001] The present invention relates to a thermochromic writing instrument and a friction tool. More specifically, it relates to a friction tool for erasing or changing the color of a handwriting made with thermochromic ink by heating, and a thermochromic writing instrument provided with such a friction tool.

Background Art

[0002] Patent Document 1 discloses a writing instrument including a first erasing member for erasing a handwriting made with thermochromic ink and a second erasing member for erasing a handwriting of a different type from the thermochromic ink.

[0003] In Example 4 of Patent Document 1, a writing instrument is disclosed in which a knock cover, which is a first erasing member, is attached to the rear end of a writing body such as a ballpoint pen, and a second erasing member is held inside the knock cover and at the rear end of the writing body. In Example 5 of Patent Document 1, a writing instrument provided with an erasing tool in which the first erasing member and the second erasing member are integrally formed is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technique disclosed in Example 4 of Patent Document 1, the first erasing member is detachably attached to the shaft cylinder, and the second erasing member is fixed to the shaft cylinder. In this configuration, since the second erasing member is covered by the first erasing member, there is no risk of being soiled by external factors. However, when using the second erasing member, it is necessary to remove the first erasing member. There is a risk of losing the first erasing member when it is removed.

[0006] In the technology disclosed in Example 5 of Patent Document 1, the first or second erasing tool is configured to fit with the inner surface of the erasing member holder. In this configuration, when the erasing member wears down, the erasing member holder may not be able to stably hold the erasing tool, and it may fall off unexpectedly.

[0007] The present invention solves the aforementioned problems of the conventional invention and aims to provide a thermochromic writing instrument and friction tool in which the friction body is not susceptible to contamination by external factors, there is no risk of losing parts when using the friction body, and in addition, there is no risk of the friction body unexpectedly falling out of the cylindrical body when the friction body wears down. [Means for solving the problem]

[0008] The first invention of the present application is a thermochromic writing instrument comprising: a cylindrical body which is a shaft or cap having an opening at one end; a thermochromic ink which can be decolorized or discolored by heating; and a friction tool which is detachably attached to the opening of the cylindrical body, wherein the friction tool comprises a friction body which rubs against the writing made by the thermochromic ink to decolorize or discolor the writing, and a lid which is detachably attached to the opening of the cylindrical body, the friction body and the lid are connected, and in a state in which the lid of the friction tool is attached to the opening of the cylindrical body, the friction body is located inside the opening and the friction body is not in contact with the inner surface of the opening.

[0009] In the thermochromic writing instrument of the first invention described above, when the friction tool is attached to the cylindrical body, the friction body is positioned in the space enclosed by the lid and the cylindrical body. As a result, the friction body does not come into contact with the outside and can be stored without becoming contaminated. Furthermore, the friction body does not come into contact with the inner surface of the opening. That is, the friction body does not affect the attachment of the friction tool to the cylindrical body. This prevents the friction body from accidentally falling off due to wear. In addition, since the friction tool has a configuration that includes a lid and a friction body, there is no risk of losing the lid when using the friction tool (rubbing the writing with the friction body) due to the lid being left unattended.

[0010] The second invention of this application is a thermochromic writing instrument of the first invention, wherein the front end of the friction body is located in front of the foremost end of the lid.

[0011] In the thermochromic writing instrument of the second invention, the front end of the friction element is positioned forward of the frontmost end of the cap. This allows for comfortable use even when the user tilts the friction tool, as the cap does not come into contact with the paper surface.

[0012] The third invention of this application is a thermochromic writing instrument of the second invention, wherein the lid comprises a columnar inner cylinder and a cylindrical outer cylinder disposed radially outward from the inner cylinder, the friction body is provided in the inner cylinder, and the outer surface of the outer cylinder and the inner surface of the opening of the cylindrical body are detachably fitted together, or the inner surface of the outer cylinder and the outer surface of the opening of the cylindrical body are detachably fitted together.

[0013] The thermochromic writing instrument of the third invention has a double-walled lid with an inner and outer cylinder. This makes it easy to configure the friction element to be non-contact with the inner surface of the opening of the cylinder.

[0014] The fourth invention of this application is a friction tool comprising a friction body that rubs against writing made with thermochromic ink to erase or change the color of the writing, and a lid having a columnar inner cylinder and a cylindrical outer cylinder arranged radially outward from the inner cylinder, wherein the friction body is provided in the inner cylinder and the front end of the friction body is located in front of the front end of the outer cylinder.

[0015] In the friction tool of the fourth invention described above, the front end of the friction body is positioned in front of the front end of the outer cylinder of the lid. This allows for comfortable use when the user tilts the friction tool, without the outer cylinder of the lid coming into contact with the paper surface. Furthermore, the lid has a double structure with an inner cylinder and an outer cylinder, and the friction body is provided in the inner cylinder. That is, the user always holds the outer cylinder and uses the friction body provided in the inner cylinder. This reduces the possibility of the user touching the friction body and also reduces the possibility of soiling the friction body. In addition, since the friction tool has a lid and a friction body, there is no risk of the lid being left unattended or lost when using the friction tool (rubbing the ink with the friction body).

[0016] The fifth invention of this application is a friction tool of the fourth invention, wherein there is a gap radially inward of the outer cylinder and radially outward of the inner cylinder.

[0017] The friction tool of the fifth invention has an annular gap radially inward of the outer cylinder and radially outward of the inner cylinder. This reduces the possibility of the user coming into contact with the friction body, that is, it reduces the possibility of the friction body becoming contaminated.

[0018] The sixth invention of this application is a friction tool of the fifth invention, wherein the inner cylinder has a cavity located radially inward.

[0019] The friction device of the sixth invention has a cavity. By making the wall thickness of the lid approximately constant due to the gap and cavity, the amount of material used can be reduced. This is preferable from the viewpoint of both the environment and cost. Furthermore, when the lid is injection molded using synthetic resin, molding defects (such as sink marks) are less likely to occur.

[0020] The seventh invention of this application is a friction tool of the sixth invention, wherein the cover has at least one hole through which the gap and the rear of the cover communicate.

[0021] The friction tool of the seventh invention has a hole through which the gap communicates with the rear of the lid body. The hole serves as an air passage that connects the outside and the inside of the lid body. Even if an infant accidentally swallows the friction tool, this air passage allows for ventilation and ensures the airway.

Advantages of the Invention

[0022] In the present invention, there is no risk that the friction body will be soiled by external factors, no risk of loss of parts when using the friction body, and in addition, there is no risk that the friction body will unexpectedly fall off from the cylindrical body when the friction body wears out. A thermochromic writing instrument and a friction tool are provided.

Brief Description of the Drawings

[0023] [Figure 1] It is a longitudinal sectional view of the main part of the thermochromic writing instrument according to an embodiment of the present invention. [Figure 2] It is a friction tool according to the first embodiment of the present invention, where (a) is a front view, (b) is a longitudinal sectional view, and (c) is a perspective view. [Figure 3] It is a friction tool according to the second embodiment of the present invention, where (a) is a front view, (b) is a longitudinal sectional view, (c) is a perspective view of a half section, and (d) is a sectional view taken along line A-A. [Figure 4] It is a friction tool according to the third embodiment of the present invention, where (a) is a longitudinal sectional view and (b) is a perspective view. [Figure 5] It is a friction tool according to the fourth embodiment of the present invention, where (a) is a front view, (b) is a longitudinal sectional view, and (c) is a perspective view.

Modes for Carrying Out the Invention

[0024] The definitions of directions and the like used in this embodiment will be described. In the thermochromic writing instrument 1 and friction tool 3, the direction in which the axis (central axis or axis line) of the cylinder 2 and lid 5 extends is defined as the axial direction, the direction perpendicular to the axial direction is defined as the radial direction, and the direction along the circumference around the axis is defined as the circumferential direction. Furthermore, the side of the friction body 4 (bottom of the drawing) is defined as the front, and the side of the lid 5 (top of the drawing) is defined as the rear. Accordingly, the direction parallel to the axial direction is sometimes referred to as the front-to-back direction. The state in which the cylinder 2 and friction tool 3 are fitted together is sometimes referred to as the fitted state.

[0025] <Embodiment of a thermochromic writing instrument> Figure 1 shows a thermochromic writing instrument 1 according to an embodiment of the present invention. The thermochromic writing instrument 1 according to this embodiment comprises a cylindrical body 2 and a friction tool 3.

[0026] • Thermochromic writing instrument 1 The thermochromic writing instrument 1 in this invention is either a retractable writing instrument in which the pen tip extends and retracts from a hole at the front end of the barrel, or a capped writing instrument in which a cap covering the pen tip protruding from the barrel is attached to and detached from the barrel. The above two types of thermochromic writing instruments 1 are configured to contain thermochromic ink inside the barrel and to dispense thermochromic ink from the pen tip.

[0027] Retractable writing instruments include side-slide type, in which an operating part protruding from the rear side wall of the barrel is slid in the front-rear direction; rear-end knock type, in which an operating part located at the rear end of the barrel is pressed forward; side-knock type, in which an operating part protruding from the side wall of the barrel is pressed radially inward; and rotary type, in which an operating part at the rear of the barrel is rotated. Each of the above retractable writing instruments is equipped with a known retraction mechanism, such as a rotating cam mechanism. The pen tip is also equipped with a known pen tip, such as a ballpoint pen tip in which a ball is rotatably held at the front end.

[0028] Capped writing instruments include direct-ink types, which contain liquid ink inside the barrel and have an ink flow rate adjustment member interposed, and cotton-filled types, which impregnate an ink-absorbing material made of fiber bundles contained inside the barrel with ink and supply ink to the writing tip. Furthermore, pen tips for direct-ink and cotton-filled types include known pen tips such as marking pens with capillary gaps made of fiber processed material or porous material, and ballpoint pen tips.

[0029] The thermochromic ink housed inside the barrel is preferably a reversible thermochromic ink. Reversible thermochromic inks can be configured using various types, either alone or in combination, such as a heat-decolorizing type that decolorizes upon heating from a colored state, a color-memory-retaining type that alternately stores a colored state or a decolorized state within a specific temperature range, or a heat-developing type that develops color upon heating from a decolorized state and returns to a decolorized state upon cooling from the colored state.

[0030] Furthermore, the colorant contained in the reversible thermochromic ink is preferably a reversible thermochromic microcapsule pigment, which is a reversible thermochromic composition containing at least three essential components that have been conventionally known: (a) an electron-donating color-developing organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the color reaction between the two occurs, encapsulated in a microcapsule.

[0031] ·Cylinder 2 In this invention, the cylindrical body 2 is the barrel or cap of the thermochromic writing instrument 1 described above. From the viewpoint of cost, the material of the barrel and cap may be resin, particularly polycarbonate or polypropylene, or from the viewpoint of appearance, wood or metal (for example, stainless steel) may be selected.

[0032] The cylindrical body 2 is a cylindrical column, for example, a cylindrical body. The cylindrical body 2 has an opening 21 at one end. The opening 21 may extend through to the other end of the cylindrical body 2. In other words, the cylindrical body 2 may be a hollow cylindrical body. In this embodiment, the cylindrical body 2 has an opening 21 at its rear end that opens to the rear.

[0033] A friction tool 3, described later, is detachably attached to the inner or outer circumferential surface of the opening 21. For this reason, the inner or outer circumferential surface of the opening 21 has a fitting portion 22 for detachably attaching the friction tool 3. Fitting methods include over-fitting, screwing, and press-fitting. When the fitting portion 22 is present on the outer circumferential surface of the opening 21, that is, when the outer circumferential surface of the opening 21 and the inner circumferential surface of the outer cylinder 51 of the friction tool 3 are fitted together, the user grasps the outer surface of the friction tool 3 and attaches and detaches it from the cylinder 2. In the above configuration, it is easier for the user to grasp the outer surface of the friction tool 3, making it easy to attach and detach the friction tool 3 from the cylinder 2, and also making it easier to rub off the writing with the friction tool 3. When the fitting portion 22 is present on the inner circumferential surface of the opening 21, that is, when the inner circumferential surface of the opening 21 and the outer circumferential surface of the outer cylinder 51 of the friction tool 3 are fitted together, it is easy to manufacture the friction tool 3. In this embodiment, the outer circumferential surface of the opening 21 has a fitting portion 22, the fitting portion 22 being an annular projection that protrudes radially outward and overcomes and engages with the fitted portion 56 of the friction tool 3.

[0034] The cylindrical body 2 has a main body portion 24 that is integrally connected to the opening 21 from axial front to front. The outer diameter of the peripheral wall of the main body portion 24 may be larger than the outer diameter of the peripheral wall of the opening 21. The cylindrical body 2 may also have a horizontal first contact portion 23 between the opening 21 and the main body portion 24. In the fitted state of this embodiment, the first contact portion 23 and the front end surface of the outer cylinder 51 of the lid 5 come into contact, restricting the forward movement of the friction tool 3.

[0035] The cylindrical body 2 may have cylindrical protrusions (not shown) on its outer surface other than the opening 21, projecting radially outward with the radial direction as its central axis. The hollow portion 55 of the friction tool 3, described later, may be inserted into the protrusion from the radially outward direction. In other words, the outer surface of the protrusion and the inner surface of the hollow portion 55 of the friction tool 3 may be fixed together. This makes it possible to use the friction body 4 (to rub with the friction body 4) in a state where the friction tool 3 is fixed to the cylindrical body 2, that is, where the friction tool 3 protrudes radially outward from the cylindrical body 2.

[0036] <Friction device of the first embodiment> As shown in Figure 2, the friction device 3 of this embodiment comprises a friction body 4 and a cover body 5. The friction device 3 may be made by combining the friction body 4 and the cover body 5 from different materials. Alternatively, the friction device 3 may be made by integrally molding the friction body 4 and the cover body 5 by two-color molding.

[0037] ·Friction body 4 The friction element 4 can erase or change the color of the ink by rubbing it against the ink's writing surface, generating frictional heat. The material of the friction element 4 is preferably an elastic synthetic resin (rubber, elastomer), 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), or a mixture of two or more rubber elastic materials, or a mixture of a rubber elastic material and a synthetic resin. The elastic synthetic resin constituting the friction element 4 is not a highly abrasive elastic material (e.g., an eraser), but a low-abrasion elastic material that produces almost no wear residue (eraser residue) during friction.

[0038] The friction body 4 has a columnar base 41 and a friction portion 42 integrally connected forward from the front end of the base 41. The shape of the friction portion 42 is a so-called bullet shape, in which the outer diameter decreases as it extends forward in the axial direction. However, the shape of the base 41 and friction portion 42 of the friction body 4 is not limited to the above configuration, and may be cylindrical or polygonal prism shape, etc. In this embodiment, the friction body 4 has a cylindrical base 41 and a bullet-shaped friction portion 42 in which the outer diameter of the front end of the base 41 and the outer diameter of the rear end of the friction portion 42 are substantially the same and are smoothly and integrally connected.

[0039] The friction body 4 may have an internal space 44 that is open to the rear and is hollow inside. It is preferable that the friction body 4 has a substantially constant wall thickness due to this internal space 44. This makes it less likely for molding defects such as sink marks to occur. It is preferable that the front of the internal space 44 is closed and has a bottom shape. In this embodiment, the friction body 4 has an internal space 44 that extends to the center of the friction portion 42, and the front of the friction portion 42 is a closed bottom cylindrical shape.

[0040] Preferably, the friction body 4 has a locked portion 45 that is locked to a locking portion 57 of the lid 5, which will be described later. The locking method can be over-fitting, press-fitting, screwing, etc. In this embodiment, the locked portion 45 is an annular projection that protrudes radially inward from the inner surface of the internal space 44 and over-fits with the locking portion 57. This prevents the friction body 4 from falling out forward. However, when the friction body 4 and the lid 5 are molded by two-color molding, the locking portion 57 and the locked portion 45 may be omitted.

[0041] • Lid 5 The material for the lid 5 may be resin, particularly polycarbonate or polypropylene, from a cost perspective, or wood or metal (e.g., stainless steel) from an appearance perspective.

[0042] The lid 5 comprises a columnar inner cylinder 52 extending in the front-rear direction and a hollow columnar outer cylinder 51. The inner cylinder 52 and the outer cylinder 51 are arranged coaxially, and the outer cylinder 51 is positioned radially outward from the inner cylinder 52. The rear end of the inner cylinder 52 and the rear end of the outer cylinder 51 are connected by a bottom 53. In other words, the lid 5 has a double structure consisting of an inner cylinder 52, an outer cylinder 51, and a bottom 53. To put it another way, the lid 5 comprises an inner cylinder 52 that protrudes forward in a cylindrical shape from the radially inner end of the bottom 53, and an outer cylinder 51 that protrudes forward in a cylindrical shape from the radially outer end of the bottom 53.

[0043] A gap 54 is provided radially outward of the inner cylinder 52 and radially inward of the outer cylinder 51, which is a space that opens forward and is closed at the rear by the bottom 53. In the above configuration, since the user grips the outer surface of the outer cylinder 51, it is easy to reduce the possibility of touching the friction body 4. That is, it is easy to reduce the possibility of the friction body 4 becoming contaminated. Since the peripheral wall of the opening 21 of the cylindrical body 2 is inserted into this gap 54, it is preferable that the radial width of the gap 54 is greater than the wall thickness of the peripheral wall of the opening 21. The inner cylinder 52 may have a cavity 55 inside, which is a space that opens to at least one of the rear or front. It is preferable that the above-mentioned cavity 55 and gap 54 are designed so that the wall thickness of the lid 5 is approximately constant. This reduces the amount of material used, which is preferable for both the environment and cost. In particular, when the lid 5 is injection molded from synthetic resin, defects (e.g., sink marks) are less likely to occur. In this embodiment, the gap 54 may have a hole in the outer cylinder 51 or the bottom 53 that connects the gap 54 to the outside (not shown). The cavity 55 may also open to the other side and communicate with the outside; that is, the inner cylinder 52 may be hollow columnar (not shown). The cavity 55 in this embodiment is a bottomed cylindrical shape that opens to the rear and is closed to the front.

[0044] The inner cylinder 52 has a locking portion 57, and the locked portion 45 of the friction body 4 is locked to the locking portion 57. The locking portion 57 is provided on the outer surface (gap 54 side) or inner surface (cavity 55 side) of the inner cylinder 52. In this case, it is preferable that the locking portion 57 is positioned in front of the inner cylinder 52. This makes it easy for the friction portion 42 of the friction body 4 to protrude axially forward from the outer cylinder 51, and also suppresses wobbling of the friction body 4 during friction. Configurations for locking the friction body 4 include override fitting and screw fitting. In this embodiment, the locking portion 57 is an annular projection that protrudes radially outward from the outer surface of the inner cylinder 52.

[0045] In this embodiment, the inner cylinder 52 has a cylindrical large-diameter portion 521 and a cylindrical small-diameter portion 522 that extends integrally forward from the large-diameter portion 521 and has a smaller diameter than the large-diameter portion 521. A horizontal second contact portion 524 is formed between the large-diameter portion 521 and the small-diameter portion 522. The rear end surface of the friction body 4 contacts the second contact portion 524, restricting the rearward movement of the friction body 4. In addition to the above configuration, the rearward movement of the friction body 4 may also be restricted by a configuration in which the front end of the small-diameter portion 522 contacts the front end of the internal space 44. Furthermore, if the inner cylinder 52 has a multi-stage cylindrical shape, it is preferable that the cavity portion 55 also has multiple stages in order to keep the wall thickness of the lid 5 substantially constant. The above-mentioned locking portion 57 is positioned in front of the small-diameter portion 522. This makes it possible to suppress the wobbling of the friction body 4 during friction. Furthermore, multiple protrusions (for example, multiple longitudinal ribs extending in the axial direction) that project radially outward and are arranged at equal intervals in the circumferential direction may be provided between the locking portion 57 and the second contact portion 524. This further suppresses the wobbling of the friction body 4 during friction.

[0046] In this embodiment, the small-diameter portion 522 of the inner cylinder 52 is inserted into the internal space 44 of the friction body 4. This configuration is preferable because, when the friction tool 3 rubs against the writing, the small-diameter portion 522 acts as a support to increase the rigidity of the friction body 4, making it less prone to wobbling.

[0047] The front of the small-diameter portion 522 may have a tapered surface that decreases in diameter as it extends axially forward. This tapered surface facilitates the insertion of the friction body 4.

[0048] The outer cylinder 51 has a fitting portion 56, and the cylindrical body 2 is detachably fitted into the fitting portion 56. The fitting portion 56 is provided on the outer or inner surface of the outer cylinder 51. Configurations for detachably fitting the outer cylinder 51 to the cylindrical body 2 include over-fitting and screw-fitting. In this embodiment, the fitting portion 56 is an annular projection that protrudes radially inward from the inner surface of the outer cylinder 51.

[0049] The outer surface of the outer cylinder 51 is the surface that the user grips. For this reason, the total length of the outer cylinder 51 is preferably 5 mm or more, more preferably 10 mm or more, in the front-to-back direction, and in this embodiment it is 11.5 mm. In addition, the outer surface of the outer cylinder 51 may be given a textured surface (such as a textured finish or knurling) to prevent slipping. Furthermore, the outer cylinder may have a polygonal shape.

[0050] In this embodiment, the fitting portion 22 on the outer surface of the cylindrical body 2 and the fitted portion 56 on the inner surface of the outer cylinder 51 are detachably fitted together. As a result, the friction body 4 is not used to fit the friction tool 3 and the cylindrical body 2, and even if the friction body 4 wears down, it does not affect the fitted state of the cylindrical body 2 and the friction tool 3. In other words, even if the friction body 4 wears down, there is no risk of it unexpectedly falling off.

[0051] In the fitted state, the peripheral wall of the opening 21 of the cylindrical body 2 is inserted into the gap 54, and the inner cylinder 52 and friction body 4 are inserted radially inward of the opening 21 of the cylindrical body 2. In the fitted state, the friction body 4 is located in the space surrounded by the lid 5 and the cylindrical body 2 and does not come into contact with the outside, so the friction body 4 can be stored without getting dirty. Furthermore, in the fitted state, it is preferable that the rear end surface of the cylindrical body 2 is positioned in front of the inner surface of the bottom 53 of the lid 5, in other words, that there is a gap between the rear end surface of the cylindrical body 2 and the bottom 53 of the lid 5. This does not affect the fitting of the cylindrical body 2 and the friction device 3.

[0052] It is preferable to design the maximum outer diameter of the inner cylinder 52 and the maximum outer diameter of the friction body 4 to be smaller than the inner diameter of the opening 21 of the cylindrical body 2. In other words, it is preferable that the inner cylinder 52 and the friction body 4 do not come into contact with the inner surface of the opening 21. This prevents the friction body 4 from becoming contaminated inside the cylindrical body 2. Furthermore, when the cylindrical body 2 and the friction tool 3 are fitted together, they can be inserted without resistance. In addition, since the friction body 4 does not participate in the fitting of the friction tool 3 and the cylindrical body 2, wear of the friction body 4 does not affect the fitted state of the cylindrical body 2 and the friction tool 3.

[0053] Furthermore, it is preferable that the maximum outer diameter of the friction body 4 is larger than the outer diameter of the large-diameter portion 521 of the inner cylinder 52. This makes it easier to insert the friction tool 3 into the cylinder 2. Specifically, since the front end of the large-diameter portion 521 of the lid 5 does not come into contact with the rear end of the opening 21 of the cylinder 2, the friction tool 3 can be easily inserted into the cylinder 2.

[0054] Preferably, the front end of the friction element 4 protrudes axially forward more than the front end of the outer cylinder 51. This prevents the outer cylinder 51 from coming into contact with the paper surface when the user tilts the friction tool 3 during use.

[0055] The thermochromic writing instrument 1 of this embodiment comprises a cylindrical body 2 which is a barrel or cap having an opening 21 at one end, a thermochromic ink that can be decolorized or discolored by heating, and a friction tool 3 that is detachably attached to the opening 21 of the cylindrical body 2, wherein the friction tool 3 comprises a friction body 4 that rubs against the writing made with the thermochromic ink to decolorize or discolor the writing, and a lid 5 that is detachably attached to the opening 21 of the cylindrical body 2, the friction body 4 and the lid 5 are connected, and when the lid 5 of the friction tool 3 is attached to the opening 21 of the cylindrical body 2, the friction body 4 is located inside the opening 21 and the friction body 4 is not in contact with the inner surface of the opening 21. In the thermochromic writing instrument 1 of this embodiment, when the friction tool 3 is attached to the cylindrical body 2, the friction body 4 is arranged in the space surrounded by the lid 5 and the cylindrical body 2. As a result, the friction element 4 can be stored without getting dirty because it does not come into contact with the outside. Also, the friction element 4 is not in contact with the inner surface of the opening 21. In other words, the friction element 4 does not affect the attachment of the cylinder 2 and the friction tool 3. This prevents the friction element 4 from accidentally falling off due to wear. Furthermore, since the friction tool 3 has a lid 5 and a friction element 4, there is no risk of losing the lid 5 when using the friction tool 3 (rubbing the ink with the friction element 4) because the lid 5 is left unattended.

[0056] In this embodiment of the thermochromic writing instrument 1, the front end of the friction element 4 is positioned in front of the foremost end of the lid 5. This allows for comfortable use even when the user tilts the friction element 3, without the lid 5 coming into contact with the paper.

[0057] The thermochromic writing instrument 1 of this embodiment has a lid 5 comprising a columnar inner cylinder 52 and a cylindrical outer cylinder 51 positioned radially outward from the inner cylinder 52. The friction body 4 is provided in the inner cylinder 52, and the outer surface of the outer cylinder 51 and the inner surface of the opening 21 of the cylindrical body 2 are detachably fitted together, or the inner surface of the outer cylinder 51 and the outer surface of the opening 21 of the cylindrical body 2 are detachably fitted together. The thermochromic writing instrument 1 of this embodiment has a double structure in which the lid 5 has an inner cylinder 52 and an outer cylinder 51. This makes it easy to configure the friction body 4 to be non-contact with the inner surface of the opening 21 of the cylindrical body 2.

[0058] The friction tool 3 of this embodiment comprises a friction body 4 that rubs against writing made with thermochromic ink to erase or change the color of the writing, and a lid 5 having a columnar inner cylinder 52 and a cylindrical outer cylinder 51 arranged radially outward from the inner cylinder 52. The friction body 4 is provided in the inner cylinder 52, and the front end of the friction body 4 is located in front of the front end of the outer cylinder 51. In the friction tool 3 of this embodiment, the front end of the friction body 4 is located in front of the front end of the outer cylinder 51 of the lid 5. This allows for comfortable use when the user tilts the friction tool 3, without the outer cylinder 51 of the lid 5 coming into contact with the paper surface. Furthermore, the lid 5 has a double structure with an inner cylinder 52 and an outer cylinder 51, and the friction body 4 is provided in the inner cylinder 52. That is, the user always grips the outer cylinder 51 and uses the friction body 4 provided in the inner cylinder 52. This reduces the possibility of the user touching the friction body 4 and also reduces the possibility of soiling the friction body 4. Furthermore, since the friction tool 3 has a lid 5 and a friction body 4, when using the friction tool 3 (rubbing the ink with the friction body 4), the lid 5 is left behind, and there is no risk of losing the lid 5.

[0059] The friction tool 3 of this embodiment has a gap 54 radially inward of the outer cylinder 51 and radially outward of the inner cylinder 52. The friction tool 3 of this embodiment has an annular gap 54 radially inward of the outer cylinder 51 and radially outward of the inner cylinder 52. This reduces the possibility of the user touching the friction body 4. In other words, it reduces the possibility of the friction body 4 becoming contaminated.

[0060] The friction tool 3 of this embodiment has a cavity 55 radially inward of the inner cylinder 52. The friction tool 3 of this embodiment has a cavity 55. By making the wall thickness of the lid 5 approximately constant due to the gap 54 and the cavity 55, the amount of material used can be reduced. This is preferable from the viewpoint of both the environment and cost. Furthermore, when the lid 5 is injection molded using synthetic resin, molding defects (such as sink marks) are less likely to occur.

[0061] <Friction device according to the second embodiment> As shown in Figure 3, the friction device 3 of this embodiment comprises a friction body 4 and a cover body 5. The friction device 3 may be made by combining the friction body 4 and the cover body 5 from separate materials. Alternatively, the friction device 3 may be integrally molded by two-color molding of the friction body 4 and the cover body 5. A detailed description of the parts that are substantially the same as the friction device 3 of the first embodiment will be omitted.

[0062] The lid 5 comprises a columnar inner cylinder 52 extending in the front-rear direction and a hollow columnar outer cylinder 51. The inner cylinder 52 and the outer cylinder 51 are arranged coaxially, and the outer cylinder 51 is positioned radially outward of the inner cylinder 52. The rear end of the inner cylinder 52 and the rear end of the outer cylinder 51 are connected by a bottom 53. In other words, the lid 5 has a double structure consisting of the inner cylinder 52, the outer cylinder 51, and the bottom 53. A gap 54 is provided radially outward of the inner cylinder 52 and radially inward of the outer cylinder 51, which is a space that opens forward and is closed at the rear by the bottom 53.

[0063] The inner cylinder 52 may have a cavity 55 inside, which is a space that opens to at least one of the rear or front ends. Preferably, the cavity 55 and gap 54 described above are designed so that the wall thickness of the lid 5 is substantially constant. This makes it less likely for defects (such as sink marks) to occur during the molding of the lid 5. The cavity 55 may also open to the other end and communicate with the outside, that is, the inner cylinder 52 may be hollow columnar. In this embodiment, the cavity 55 is a bottomed cylindrical shape that opens to the rear and is closed at the front.

[0064] The lid 5 may have at least one hole 523 through which the gap 54 and the rear of the lid 5 communicate. For example, as in this embodiment, the inner cylinder 52 may have a hole 523 that penetrates radially inward and outward through the entire length of the large-diameter portion 521 of the inner cylinder 52, that is, from the bottom portion 53 to the second contact portion 524. In other words, the inner cylinder 52 may have a through hole through which the cavity portion 55 and the gap 54 communicate. The inner cylinder 52 may have multiple holes 523 at equal intervals in the circumferential direction. In this embodiment, the inner cylinder 52 has three holes at equal intervals in the circumferential direction. These holes 523 ensure that even if an infant accidentally swallows the friction tool 3, a certain amount of air passage can be secured and the airway can be maintained because the inside and outside of the inner cylinder 52 are in communication. Similar holes may be appropriately provided in the friction tool 3 of the first embodiment (Figure 2), the friction tool 3 of the third embodiment (Figure 4), and the friction tool 3 of the fourth embodiment (Figure 5).

[0065] In this embodiment, the friction device 3 has a lid 5 that has at least one hole 523 through which the gap 54 and the rear of the lid 5 communicate. The friction device 3 in this embodiment has a hole 523 through which the gap 54 and the rear of the lid 5 communicate. The hole 523 serves as an air passage that connects the outside and inside of the lid 5. Even if an infant accidentally swallows the friction device 3, this air passage allows for ventilation and ensures an open airway.

[0066] <Friction device of the third embodiment> As shown in Figure 4, the friction device 3 of this embodiment comprises a friction body 4 and a cover body 5. The friction body 4 and the cover body 5 may be molded from separate components and then combined, or they may be integrally molded from different materials by two-color molding. A detailed description of the parts of the friction body 4 and cover body 5 of this embodiment that are substantially the same as those of the first embodiment will be omitted.

[0067] ·Friction body 4 The friction body 4 of this embodiment has a cylindrical base portion 41 and a friction portion 42 integrally connected forward from the front end of the base portion 41. The shape of the friction portion 42 is a so-called bullet shape, in which the outer diameter of the rear end of the friction portion 42 is larger than the outer diameter of the front end of the base portion 41, and the outer diameter decreases as it extends axially forward. A rearward-facing step portion 43 is formed between the front end of the base portion 41 and the rear end of the friction portion 42. The friction body 4 is prevented from falling backward by the contact between the front end surface of the inner cylinder 52 and the rearward-facing step portion 43.

[0068] The friction body 4 has a locked portion 45 that is locked to a locking portion 57 of the cover 5. Locking methods include override fitting, press-fit fitting, and screwing. In this embodiment, the locked portion 45 is an annular projection that protrudes radially outward from the outer surface of the base portion 41 and engages with the locking portion 57 by override fitting. This prevents the friction body 4 from falling forward.

[0069] • Lid 5 The lid 5 comprises a columnar inner cylinder 52 extending in the front-rear direction and a hollow columnar outer cylinder 51. The inner cylinder 52 and the outer cylinder 51 are arranged coaxially, and the outer cylinder 51 is positioned radially outward of the inner cylinder 52. The rear end of the inner cylinder 52 and the rear end of the outer cylinder 51 are connected by a bottom 53. In other words, the lid 5 has a double structure consisting of the inner cylinder 52, the outer cylinder 51, and the bottom 53. A gap 54 is provided radially outward of the inner cylinder 52 and radially inward of the outer cylinder 51, which is a space that opens forward and is closed at the rear by the bottom 53.

[0070] The inner cylinder 52 may have a cavity 55 inside, which is a space that opens to at least one of the rear or front ends. In this embodiment, the cavity 55 is open both at the rear and the front; in other words, the inner cylinder 52 has a hollow cylindrical shape. The base 41 of the friction body 4 is inserted from the front through this opening at the front of the inner cylinder 52. That is, when the friction body 4 is attached to the lid 5, the base 41 of the friction body 4 is positioned inside the cavity 55. The inner cylinder 52 has a locking portion 57, which is an annular projection that protrudes radially inward from the inner surface of the inner cylinder 52 (the side of the cavity 55). In addition, a plurality of vertical ribs may be provided between the front end of the inner cylinder 52 and the locking portion 57, protruding radially inward, extending axially, and arranged at equal intervals in the circumferential direction. This reduces the likelihood of the friction body 4 wobbling during friction.

[0071] The outer cylinder 51 has a fitting portion 56, and the cylindrical body 2 is detachably fitted into the fitting portion 56. In this embodiment, the fitting portion 56 is a spiral projection that protrudes radially inward from the inner surface of the outer cylinder 51 and advances forward as it progresses in one radial direction. This spiral projection may be arranged continuously or intermittently in the circumferential direction.

[0072] In a configuration where the inner cylinder 52 of the lid 5 is hollow cylindrical and the base 41 of the friction body 4 is positioned inside the cavity 55, the friction body 4 can be easily replaced when it wears out. Specifically, to remove it, a rod with approximately the same diameter as the base 41 of the friction body 4 is inserted from the rear through the opening at the rear of the cavity 55, and the friction body 4 is pressed forward and pushed out. Specifically, to install it, with a part of the base 41 inserted into the opening at the front of the internal gap 54, the friction body 4 is pressed backward and locked in place. The friction body 4 can be easily replaced by the above process.

[0073] <Friction device of the fourth embodiment> As shown in Figure 4, the friction device 3 of this embodiment comprises a friction body 4 and a cover 5. The friction body 4 and the cover 5 may be molded from separate components and combined, or they may be integrally molded from a different material by two-color molding. Detailed descriptions of parts that are substantially the same as those of the first and third embodiments are omitted.

[0074] • Lid 5 The lid 5 comprises a columnar inner cylinder 52 extending in the front-rear direction and a hollow columnar outer cylinder 51. The inner cylinder 52 and the outer cylinder 51 are arranged coaxially, and the outer cylinder 51 is positioned radially outward of the inner cylinder 52. The rear end of the inner cylinder 52 and the rear end of the outer cylinder 51 are connected by a bottom 53. In other words, the lid 5 has a double structure consisting of the inner cylinder 52, the outer cylinder 51, and the bottom 53. A gap 54 is provided radially outward of the inner cylinder 52 and radially inward of the outer cylinder 51, which is a space that opens forward and is closed at the rear by the bottom 53.

[0075] The inner cylinder 52 may have a cavity 55 inside, which is a space that opens to at least one of the rear or front ends. In this embodiment, the internal gap 54 is open at the front and closed at the rear. In other words, the inner cylinder 52 has a bottomed cylindrical shape that opens to the front.

[0076] The outer cylinder 51 has a fitting portion 56, and the cylindrical body 2 is detachably fitted into the fitting portion 56. In this embodiment, the fitting portion 56 is a spiral projection that protrudes radially outward from the outer surface of the outer cylinder 51 and advances as it moves in one direction in the circumferential direction. The configuration in which the fitting portion 56 is on the outer surface of the outer cylinder 51 is preferable because it facilitates the molding of the lid 5. In the configuration in which the fitting portion 56 is on the outer surface of the outer cylinder 51, a fitting portion 22 is provided on the inner surface of the opening 21 of the cylindrical body 2 (not shown).

[0077] In the fitted state, the outer cylinder 51, inner cylinder 52, and friction body 4 are inserted radially inward into the opening 21 of the cylindrical body 2. In the fitted state, the friction body 4 is located in the space surrounded by the lid 5 and the cylindrical body 2 and does not come into contact with the outside, so the friction body 4 can be stored without getting dirty. Furthermore, with the above configuration, non-contact between the cylindrical body 2 and the friction body 4 can be made more reliable. That is, the friction body 4 is not used for fitting the friction tool 3 and the cylindrical body 2. As a result, even if the friction body 4 wears down, it does not affect the fitted state between the cylindrical body 2 and the friction tool 3. In other words, even if the friction body 4 wears down, there is no risk of it unexpectedly falling off. [Explanation of Symbols]

[0078] 1. Thermochromic writing instruments 2 cylinders 21 Opening 22 Fitting part 23 First contact part 24 Main body 3 Friction tool 4 Friction body 41 Base 42 Friction area 43 Step part 44 Interior space 45 Locked part 5. Lid 51 Outer cylinder 52 Inner cylinder 521 Large diameter section 522 Small diameter section 523 holes 524 Second contact part 53 Bottom 54 Gap 55 Cavity 56 Fitting part 57 Locking part

Claims

1. A cylindrical body which is a shaft cylinder or cap having an opening at one end, A heat-sensitive ink that can be decolorized or discolored by heating, A friction device that is detachably attached to the opening of the cylindrical body, A thermochromic writing instrument equipped with, The aforementioned friction device is A friction body that rubs against the ink used to erase or change the color of the ink, The cylindrical body comprises a lid that is detachably attached to the opening, The friction body and the cover are connected, With the lid of the friction tool attached to the opening of the cylindrical body, The friction body is located inside the opening, and A thermochromic writing instrument characterized in that the friction element is not in contact with the inner surface of the opening.

2. The thermochromic writing instrument according to claim 1, characterized in that the front end of the friction body is located in front of the foremost end of the cover.

3. The lid comprises a columnar inner cylinder and a cylindrical outer cylinder positioned radially outward from the inner cylinder. The friction body is provided in the inner cylinder. The thermochromic writing instrument according to claim 2, characterized in that the outer surface of the outer cylinder and the inner surface of the opening of the cylindrical body are detachably fitted together, or the inner surface of the outer cylinder and the outer surface of the opening of the cylindrical body are detachably fitted together.

4. A friction body that rubs against handwriting made with thermochromic ink to erase or change the color of the handwriting, A friction tool comprising a lid having a columnar inner cylinder and a cylindrical outer cylinder positioned radially outward from the inner cylinder, The friction body is provided in the inner cylinder, A friction device characterized in that the front end of the friction body is located forward of the front end of the outer cylinder.

5. The friction device according to claim 4, characterized in that the cover has a gap radially inward of the outer cylinder and radially outward of the inner cylinder.

6. The friction device according to claim 5, characterized in that it has a cavity in the radially inward direction of the inner cylinder.

7. The friction device according to claim 6, characterized in that the cover has at least one hole through which the gap and the rear of the cover communicate.

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