Friction and writing implements

Abstract

To provide a friction tool capable of suppressing torque applied by a user being wasted.SOLUTION: A friction tool includes a mounting member, a friction body and a hook part. The mounting member includes a first screw provided at a writing tool, a second screw engageable involving rotation around a rotational axis, and a cylindrical first outer surface extending along the rotational axis. The friction body surrounds the mounting member, can generate frictional heat for thermally discoloring the handwriting in thermochromic ink, and includes an inner surface coming into contact with the first outer surface and a second outer surface positioned on the opposite side from the inner surface. The hook part includes a first protrusion protruding from the second outer surface, or a recess which is recessed from the second outer surface.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to a friction tool and a writing tool. [Background technology]

[0002] Writing implements for writing with thermochromic ink have been known in the past. The handwriting with the thermochromic ink changes color to transparent or another color due to frictional heat generated by rubbing the ink against a friction body, for example.

[0003] For example, a friction device having a friction body is replaceably attached to the rear end of a writing instrument. The friction device has, for example, an attachment member surrounded by the friction body and provided with a female screw. The female screw of the attachment member engages with a male screw provided at the rear end of the writing instrument, thereby attaching the friction device to the writing instrument. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-203590 Summary of the Invention [Problem to be solved by the invention]

[0005] When the friction device is attached to the writing instrument, the friction body is rotated due to the engagement of the female screw and the male screw. When the friction body is rotated, it is, for example, gripped by a user. However, for example, slippage between the outer surface of the friction body and the user's finger or elastic deformation of the friction body may cause loss (waste) of torque applied to the friction device by the user.

[0006] One example of a problem to be solved by the present invention is to provide a friction device that can prevent torque applied by a user from being wasted, and a writing instrument that includes the friction device. [Means for solving the problem]

[0007] A friction tool according to one embodiment of the present invention includes an attachment member, a friction body, and a hook portion. The attachment member is attached to a first screw provided on a writing instrument. to The friction body has a second screw that can be engaged with rotation about a rotation axis, and a cylindrical first outer surface that extends along the rotation axis. a peripheral wall including the first outer surface, an inner surface provided on the peripheral wall and in contact with the first outer surface, and a second outer surface provided on the peripheral wall and positioned opposite the inner surface, It is possible to generate frictional heat that causes the thermochromic ink to change color. R The hook portion is a protrusion provided on the mounting member and protruding from the first outer surface; protruding from the second outer surface protrusion It has. An end of the second outer surface in a first axial direction along the rotation axis is located on the first axial side relative to an end of the projection in a second axial direction opposite to the first axial direction. [Effects of the Invention]

[0008] According to the present invention, for example, it is possible to suppress the torque applied to the friction tool by the user from being wasted. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing a thermochromic writing instrument according to a first embodiment. [Figure 2] FIG. 2 is a perspective view showing the friction device of the first embodiment. [Figure 3] FIG. 3 is a perspective view showing the friction device of the first embodiment from a different direction than FIG. [Figure 4] FIG. 4 is a cross-sectional view showing the friction device of the first embodiment taken along line F4-F4 in FIG. [Figure 5] FIG. 5 is a perspective view showing a friction device according to a second embodiment. [Figure 6] FIG. 6 is a perspective view showing the friction device of the second embodiment from a different direction than FIG. [Figure 7] FIG. 7 is a cross-sectional view showing the friction device of the second embodiment taken along line F7-F7 in FIG. [Figure 8] FIG. 8 is a cross-sectional view showing the friction device of the second embodiment taken along line F8-F8 in FIG. [Figure 9] FIG. 9 is a perspective view showing a friction device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] (First embodiment) The first embodiment will be described below with reference to FIGS. 1 to 4. In this specification, components according to the embodiment and descriptions of the components may be described using multiple expressions. The components and their descriptions are merely examples and are not limited by the expressions in this specification. The components may also be identified by names different from those in this specification. Furthermore, the components may also be described using expressions different from those in this specification.

[0011] 1 is a cross-sectional view showing a thermochromic writing instrument 10 according to a first embodiment. The thermochromic writing instrument (hereinafter referred to as "writing instrument") 10 of this embodiment is, for example, a cap-type writing instrument used to create (write) handwriting such as lines, figures, and letters using thermochromic ink. Note that the writing instrument 10 is not limited to this example and may have a knock-type, side-knock-type, or rotary-type extension / retraction mechanism, or may be another writing instrument such as a multi-core writing instrument (multi-function writing instrument).

[0012] The writing instrument 10 has a barrel 11, a writing element 12, a cap 13, and two friction elements 14. The writing instrument 10 may further have other components such as a clip.

[0013] The barrel 11 is formed in a substantially cylindrical shape extending along a central axis Ax. The central axis Ax is an imaginary axis located approximately at the center of the barrel 11. In the following description, the direction along the central axis Ax is defined as the axial direction, the direction perpendicular to (intersecting) the central axis Ax as the radial direction, and the direction rotating around the central axis Ax as the circumferential direction.

[0014] The axial direction includes the rearward direction Db and the forward direction Df. The rearward direction Db is one direction included in the axial direction. The forward direction Df is the other direction included in the axial direction and is the opposite direction to the rearward direction Db. Note that the expressions "front" and "back" used in this specification are used for convenience of explanation and do not limit orientation, position, usage mode, priority, or any other conditions.

[0015] The barrel 11 is formed in a substantially cylindrical shape extending in the axial direction. The barrel 11 has a front end 11a and a rear end 11b. The front end 11a is the end of the barrel 11 in the forward direction Df and is open. The rear end 11b is the end of the barrel 11 in the rear direction Db. The rear end 11b is located on the opposite side of the front end 11a and is closed. The rear end 11b may also be open.

[0016] The barrel 11 has a front barrel 21 and a rear barrel 22. The front barrel 21 may also be referred to as a neck barrel. The rear barrel 22 may also be referred to as a barrel. The barrel 11 may be formed from a single member, or may have three or more members.

[0017] The front axle 21 and the rear axle 22 are made of, for example, synthetic resin. However, the front axle 21 and the rear axle 22 may be made of other materials such as metal. Furthermore, the front axle 21 and the rear axle 22 may be made of different materials.

[0018] Front shaft 21 is formed in a generally cylindrical shape extending in the axial direction. End 21a of front shaft 21 in the forward direction Df and end 21b of front shaft 21 in the rearward direction Db are open. End 21a of front shaft 21 forms front end 11a of barrel 11.

[0019] The rear axle 22 is formed in a generally cylindrical shape extending in the axial direction. An end 22a of the rear axle 22 in the forward direction Df is open. On the other hand, an end 22b of the rear axle 22 in the rear direction Db is closed. The end 22b of the rear axle 22 forms the rear end 11b of the axle tube 11.

[0020] The end 21b of the front axle 21 in the rear direction Db and the end 22a of the rear axle 22 in the forward direction Df fit together. For example, the end 21b of the front axle 21 in the rear direction Db is fixed into the inside of the end 22a of the rear axle 22 in the forward direction Df by screwing or press-fitting. This forms a space 25 inside the barrel 11 that is open at the front end 11a.

[0021] The writing element 12 is a ballpoint pen capable of discharging a corresponding thermochromic ink. The writing element 12 is not limited to a ballpoint pen, but may be another component capable of discharging a thermochromic ink, such as a marker or a fountain pen. The writing element 12 of this embodiment includes, for example, an ink reservoir 31, thermochromic ink 32, a pen tip 33, and a tail cap 34.

[0022] The thermochromic ink 32 is stored in the ink reservoir 31. The pen tip 33 is attached to the ink reservoir 31 in the forward direction Df. The pen tip 33 has a ballpoint pen tip that rotatably holds a ball and is capable of discharging the thermochromic ink 32 stored in the ink reservoir 31. The ink reservoir 31 also contains a follower that comes into contact with the end face of the thermochromic ink 32 in the backward direction Db. The follower is, for example, a high-viscosity liquid or solid, and moves while following the end face of the thermochromic ink 32, preventing the thermochromic ink 32 from flowing back. A tail plug 34 is attached to the end of the ink reservoir 31 in the backward direction Db.

[0023] The thermochromic ink 32 is, for example, a reversible thermochromic ink. Reversible thermochromic inks include various types of reversible thermochromic inks, such as a thermal decolorization type that is decolorized from a colored state by heating, a color memory retention type that alternately retains the colored state or the decolorized state within a specific temperature range, and a thermal color development type that develops color from a decolorized state by heating and returns to the decolorized state by cooling from the colored state.

[0024] The reversible thermochromic ink has, for example, a reversible thermochromic microencapsulated pigment as a colorant. The reversible thermochromic microencapsulated pigment contains a reversible thermochromic composition contained in microcapsules. The reversible thermochromic composition contains at least three components: an electron-donating color-forming organic compound, an electron-accepting compound, and a reaction medium that determines the temperature at which the color-forming reaction between the electron-donating organic compound and the electron-accepting compound occurs. However, the thermochromic ink is not limited to the above examples.

[0025] The pen tip 33 of the writing element 12 protrudes from the open front end 11a of the barrel 11. In other words, the pen tip 33 of the writing element 12 can be provided at the front end 11a of the barrel 11.

[0026] The cap 13 is formed in a substantially cylindrical shape and can be selectively attached to the front end 11a or the rear end 11b of the barrel 11. When the cap 13 is attached to the front end 11a, it covers and protects the pen tip 33 provided at the front end 11a. On the other hand, when the cap 13 is attached to the rear end 11b, the pen tip 33 is exposed so that it can be used for writing.

[0027] The cap 13 has two ends 13a and 13b. The end 13a is the end of the cap 13 in the forward direction Df when the cap 13 is attached to the front end 11a. The end 13b is the end of the cap 13 in the rearward direction Db when the cap 13 is attached to the front end 11a.

[0028] The end 13a is closed, while the end 13b is open. The front end 11a or the rear end 11b of the barrel 11 is inserted into the cap 13 through the open end 13b.

[0029] The two friction devices 14 are each used to thermally change the color of the written mark made of thermochromic ink. Note that the friction devices 14 may also have other uses. One of the friction devices 14 is removably attached to the rear end 11b of the barrel 11. The other friction device 14 is removably attached to the end 13a of the cap 13.

[0030] The two friction devices 14 have approximately the same shape. Therefore, the following description will representatively describe one of the friction devices 14 attached to the rear end portion 11b of the barrel 11. The friction device 14 attached to the cap 13 can be understood by appropriately interpreting the rearward direction Db and the forward direction Df in the description of the friction device 14 attached to the barrel 11. Note that the two friction devices 14 of the writing instrument 10 may have different shapes.

[0031] Fig. 2 is a perspective view showing the friction device 14 of the first embodiment. Fig. 3 is a perspective view showing the friction device 14 of the first embodiment from a different direction than Fig. 2. Fig. 4 is a cross-sectional view showing the friction device 14 of the first embodiment along the line F4-F4 in Fig. 2. As shown in Fig. 4, the friction device 14 has an attachment member 41, a friction body 42, and a hook portion 43.

[0032] The mounting member 41 is made of a synthetic resin such as ABS resin, polycarbonate (PC) resin, polypropylene (PP) resin, polybutylene terephthalate (PBT) resin, or nylon 6,6. However, the mounting member 41 may also be made of other materials such as metal.

[0033] The mounting member 41 is formed in a cylindrical shape extending axially along the central axis Ax. Therefore, a through-hole 50 is provided inside the mounting member 41. Furthermore, the mounting member 41 has a first inner surface 51, a first outer surface 52, a first end portion 53, a second end portion 54, and a female thread 55. The female thread 55 is an example of a second thread.

[0034] The central axis Ax is located approximately in the center of the through hole 50, the first inner surface 51, the first outer surface 52, the first end 53, the second end 54, and the female thread 55. Note that the center of at least one of the through hole 50, the first inner surface 51, the first outer surface 52, the first end 53, the second end 54, and the female thread 55 may be offset from the central axis Ax.

[0035] The first inner surface 51 is formed in a substantially cylindrical shape extending in the axial direction along the central axis Ax. The first inner surface 51 faces radially inward. However, the first inner surface 51 is not limited to this example. The through hole 50 is formed inside the first inner surface 51 and extends in the axial direction along the central axis Ax. Therefore, the first inner surface 51 faces the inside of the through hole 50. A female thread 55 is provided on the first inner surface 51.

[0036] The first outer surface 52 is located on the opposite side of the first inner surface 51. The first outer surface 52 extends in the axial direction along the central axis Ax and is formed in a generally conical cylindrical shape tapering toward the rear direction Db. Note that the first outer surface 52 is not limited to this example. For example, the first outer surface 52 may be formed in a cylindrical shape with a constant diameter, or in a rectangular cylindrical shape having a polygonal outline.

[0037] The first end 53 is an end surface of the mounting member 41 in the rear direction Db. The mounting member 41 may have a portion located rearward of the first end 53. The first end 53 is formed to be substantially flat and faces the rear direction Db. One end of the through-hole 50 opens at the first end 53.

[0038] The second end 54 is an end surface of the mounting member 41 in the forward direction Df. Therefore, the second end 54 is located opposite the first end 53. The mounting member 41 may have a portion located forward of the second end 54. The second end 54 is formed to be approximately flat and faces the forward direction Df. The other end of the through-hole 50 opens at the second end 54.

[0039] The friction body 42 is made of a material containing an elastic synthetic resin (elastomer) such as silicone resin, SBS (styrene-butadiene-styrene copolymer) resin, SEBS (styrene-ethylene-butylene-styrene copolymer) resin, fluorine-based resin, chloroprene resin, nitrile resin, polyester-based resin, and ethylene propylene diene rubber (EPDM). The material of the friction body 42 may contain multiple elastomers. The material of the friction body 42 may also be a mixture of an elastomer and a synthetic resin with relatively low elasticity. The material of the friction body 42 is a low-wear elastic material that generates less wear debris (eraser dust) due to wear compared to highly wear-resistant elastic materials such as erasers.

[0040] The friction body 42 is softer than the mounting member 41. In other words, the rigidity of the friction body 42 is lower than the rigidity of the mounting member 41. Specifically, the rigidity of the friction body 42 in at least one of deformations of expansion and contraction (axial direction), bending, shear, and torsion is lower than that of the mounting member 41. Furthermore, the longitudinal modulus of elasticity, shear modulus, and bulk modulus of elasticity of the friction body 42 may be lower than those of the mounting member 41.

[0041] The friction body 42 has a peripheral wall 61 and a rear wall 62. The peripheral wall 61 and the rear wall 62 are integrally formed. The peripheral wall 61 is formed in a cylindrical shape that surrounds the mounting member 41. The rear wall 62 is formed in a substantially annular shape that covers the first end 53 of the mounting member 41. The peripheral wall 61 has a second inner surface 65 and a second outer surface 66. The second inner surface 65 is an example of an inner surface.

[0042] The second inner surface 65 surrounds the first outer surface 52 and is in contact with the first outer surface 52. In the present embodiment, the second inner surface 65 is attached to the first outer surface 52. The second outer surface 66 is located on the opposite side of the second inner surface 65. The second outer surface 66 is formed approximately parallel to the first outer surface 52. In other words, the second outer surface 66 is formed in a generally conical cylindrical shape that extends in the axial direction along the central axis Ax and tapers in the rear direction Db. Note that the second outer surface 66 is not limited to this example.

[0043] The rear wall 62 has an inner surface 67 and an outer surface 68. The inner surface 67 is in contact with the first end 53. In this embodiment, the inner surface 67 is attached to the first end 53. The outer surface 68 is located opposite the inner surface 67. The outer surface 68 is provided at the end of the friction device 14 in the rear direction Db.

[0044] A through hole 69 is provided on the inside of the annular rear wall 62. The through hole 69 axially penetrates the rear wall 62 along the central axis Ax and opens to an inner surface 67 and an outer surface 68. The through hole 69 communicates with the through hole 50 of the mounting member 41. Therefore, the friction body 42 exposes the through hole 50 of the mounting member 41 without blocking it. Furthermore, the friction body 42 does not contact the second end 54 of the mounting member 41, exposing the second end 54. The second end 54 may be covered by a part different from the friction body 42.

[0045] The thickness of each portion of the friction body 42 is different from one another. The thickness T1 of the rear wall 62 in the axial direction is greater than the thickness T2 of the peripheral wall 61 in the radial direction. The thickness of the friction body 42 may be uniform.

[0046] The hook portion 43 has a plurality of protrusions 70. The protrusions 70 are an example of first protrusions. The protrusions 70 are formed integrally with the mounting member 41. In other words, the mounting member 41 has a plurality of protrusions 70 of the hook portion 43. In other words, the protrusions 70 are provided on the mounting member 41.

[0047] The protrusions 70 protrude radially from the first outer surface 52 of the mounting member 41. The multiple protrusions 70 are arranged around the first outer surface 52 at intervals. In other words, the multiple protrusions 70 are arranged circumferentially at intervals. In this embodiment, four protrusions 70 are arranged circumferentially at equal intervals (every 90°). Note that the number and intervals of the protrusions 70 are not limited to this example. For example, only one protrusion 70 may protrude from the first outer surface 52.

[0048] The protrusions 70 are formed in the shape of plates extending in the axial direction. For example, the length of the protrusions 70 in the axial direction is longer than the length (width) of the protrusions 70 in the radial direction and longer than the length (thickness) of the protrusions 70 in the circumferential direction. Note that the length of the protrusions 70 in the axial direction may be shorter than the other of the width and thickness of the protrusions 70, as long as it is longer than one of the width and thickness of the protrusions 70.

[0049] The protrusion 70 has a trailing edge 71, a leading edge 72, and two side surfaces 73 shown in Figure 3. The trailing edge 71 is the end of the protrusion 70 in the rear direction Db and faces in the rear direction Db. The leading edge 72 is the end of the protrusion 70 in the forward direction Df and faces in the forward direction Df. The side surface 73 is the end of the protrusion 70 in the circumferential direction. The two side surfaces 73 face in opposite directions.

[0050] The length of the protrusion 70 in the axial direction is shorter than the length of the mounting member 41 in the axial direction. The length of the protrusion 70 in the axial direction is the distance between the rear edge 71 and the front edge 72 in the axial direction. The length of the mounting member 41 in the axial direction is the distance between the first end 53 and the second end 54 in the axial direction. In this embodiment, the length of the protrusion 70 in the axial direction is equal to or less than half the length of the mounting member 41 in the axial direction. Note that the length of the protrusion 70 in the axial direction is not limited to this example.

[0051] 4, the rear edge 71 of the protrusion 70 is spaced apart from the first end 53. The front edge 72 of the protrusion 70 is located at approximately the same position as the second end 54 in the axial direction. Therefore, the protrusion 70 is closer to the second end 54 than to the first end 53.

[0052] The length of the protrusion 70 in the radial direction is longer than the length (thickness) of the peripheral wall 61 in the radial direction. Therefore, the protrusion 70 penetrates the peripheral wall 61 of the friction body 42 and protrudes from the second outer surface 66. A part of the trailing edge 71 and a part of the side surface 73 are in contact with (attached to) the peripheral wall 61.

[0053] In the above-described friction tool 14, the mounting member 41 is used for mounting to the barrel 11, and the friction body 42 is used for thermochromic ink writing. For example, as shown in Fig. 1, the barrel 11 has an end face 81 and a shaft 82 at its rear end 11b.

[0054] The end surface 81 is formed to be approximately flat and faces the rear direction Db. When the friction device 14 is attached to the barrel 11, the end surface 81 faces the second end 54 of the mounting member 41. The end surface 81 abuts against the second end 54 of the mounting member 41 and supports the friction device 14.

[0055] The shaft portion 82 is formed in a cylindrical shape that protrudes from the end face 81 and extends axially along the central axis Ax. A male screw 83 is provided on the shaft portion 82. That is, the male screw 83 is provided on the rear end portion 11b of the barrel 11. The male screw 83 is an example of a first screw.

[0056] The female screw 55 of the mounting member 41 engages with the male screw 83 provided on the barrel 11 of the writing instrument 10, with rotation about the central axis Ax. That is, in this embodiment, the central axis Ax coincides with the axis of rotation when the female screw 55 and the male screw 83 engage. The central axis Ax is an example of the axis of rotation. The axis of rotation is an imaginary straight line that serves as the center of rotation when the female screw 55 and the male screw 83 are screwed together. Note that the axis of rotation when the female screw 55 and the male screw 83 are screwed together does not have to coincide with the central axis Ax.

[0057] The female thread 55 engages with the male thread 83, whereby the friction device 14 is removably attached to the rear end portion 11b of the barrel 11. Note that a through hole communicating with the through holes 50, 69 may be provided inside the barrel 82, and the barrel 11 may be open.

[0058] On the other hand, in the friction device 14 attached to the cap 13, an attachment member 41 is used for attachment to the cap 13. For example, an end face 91 and a tubular portion 92 are provided at the end 13a of the cap 13. The end face 91 is formed to be approximately flat and faces the forward direction Df. The tubular portion 92 protrudes from the end face 91 and is formed in a cylindrical shape extending in the axial direction along the central axis Ax. A male thread 93 is provided on the tubular portion 92.

[0059] The female thread 55 of the mounting member 41 engages with the male thread 93 provided on the cap 13, with rotation about the central axis Ax. This allows the friction device 14 to be removably attached to the end portion 13a of the cap 13. The cap 13 is open inside the cylindrical portion 92. The inner hole of the cylindrical portion 92 communicates with the through holes 50, 69 of the friction device 14.

[0060] The writing instrument 10 described above forms handwriting of thermochromic ink by ejecting the thermochromic ink from the pen tip 33. The friction body 42 can thermally discolor the handwriting of the thermochromic ink by frictional heat generated by rubbing the handwriting of the thermochromic ink. Note that the friction body 42 may also thermally discolor handwriting of thermochromic ink formed by a writing instrument other than the writing instrument 10.

[0061] 4, the protrusion 70 is spaced axially forward Df from the rear wall 62 of the friction body 42. Therefore, when the outer surface 68 of the rear wall 62 of the friction body 42 or the corner portion between the peripheral wall 61 and the rear wall 62 rubs the handwriting, the protrusion 70 can prevent interference with the paper surface on which the handwriting is formed. The protrusion 70 is formed so as to be spaced apart from the paper surface when the writing instrument 10 is tilted at an angle of approximately 60° relative to the paper surface, for example.

[0062] The mounting member 41 and the friction body 42 are integrally formed by, for example, double-molding. Therefore, the first outer surface 52 and the first end portion 53 of the mounting member 41 contact the friction body 42 with almost no gap. Note that a gap may exist between the mounting member 41 and the friction body 42.

[0063] For example, two components formed by two-color molding are joined, bonded, or adhered to each other depending on the combination of the materials of the two components. In this embodiment, the first outer surface 52 and the first end portion 53 are joined, bonded, or adhered to the friction body 42. This prevents the friction body 42 from coming off the mounting member 41.

[0064] The protrusions 70 of the mounting member 41 penetrate the peripheral wall 61 of the friction body 42, and a portion of the protrusions 70 is joined, bonded, or adhered to the peripheral wall 61. In other words, the protrusions 70 increase the contact area between the mounting member 41 and the friction body 42, and strengthen the joining, bonding, or adhesion between the mounting member 41 and the friction body 42.

[0065] The first outer surface 52 and the first end portion 53 may not be joined, bonded, or attached to the friction body 42. In this case, for example, a portion of the friction body 42 is housed in a hole provided in the first outer surface 52 of the mounting member 41. This prevents the friction body 42 from coming off the mounting member 41.

[0066] In two-color molding, for example, the mounting member 41 is molded first, and then the friction body 42 is molded. Note that the method of two-color molding of the mounting member 41 and the friction body 42 is not limited to this example. The friction body 42 may also be molded separately from the mounting member 41 and attached to the mounting member 41. However, by forming the friction body 42 integrally with the mounting member 41 by two-color molding, it is possible to easily mold the friction body 42, firmly attach it to the mounting member 41, and prevent the appearance of the writing instrument 10 from being impaired.

[0067] For example, pencil lead residue or dirt may be transferred to the friction body 42, soiling the friction body 42. When the soiled friction body 42 rubs against the paper surface, the dirt adhering to the friction body 42 may be transferred to the paper surface, soiling the paper surface. Therefore, when the friction body 42 becomes soiled, the friction device 14 may be replaced with a new friction device 14. Note that the friction device 14 may also be replaced with another friction device 14 for other reasons.

[0068] When replacing the friction device 14, the old friction device 14 is removed from the barrel 11, and a new friction device 14 is attached to the barrel 11. Note that the friction device 14 may be attached to and detached from the barrel 11 at other times, not just when it is replaced.

[0069] When the friction device 14 is attached to the barrel 11, the friction device 14 is rotated around the central axis Ax due to the engagement between the female thread 55 of the attachment member 41 and the male thread 83 of the barrel 11. To rotate the friction device 14, for example, the user's fingers pinch the second outer surface 66 of the friction body 42.

[0070] As described above, the rigidity of the friction body 42 is lower than the rigidity of the mounting member 41. Therefore, the friction body 42 is elastically deformed when held by the user's finger. Also, for example, in order for the friction body 42 to smoothly rub the handwriting, the surface roughness of the second outer surface 66 is set to be relatively low. Therefore, there is a risk of slippage occurring between the second outer surface 66 and the user's finger.

[0071] The elastic deformation of the friction body 42 may result in a loss (waste) of torque applied by the user to the friction device 14. For example, the torque applied by the user to the friction device 14 may be consumed by the elastic deformation of the friction body 42, which may twist the friction device 14 relative to the mounting member 41. For this reason, the user may mistakenly believe that the attachment of the friction device 14 is complete before the female thread 55 and the male thread 83 are fully engaged with each other.

[0072] Furthermore, slippage between the second outer surface 66 and the user's finger may cause a loss in the torque applied by the user to the friction device 14. For example, the user's finger may slip on the second outer surface 66. This may result in the female thread 55 and the male thread 83 not being able to fully engage with each other.

[0073] In this embodiment, a protrusion 70 is provided on the mounting member 41, which has higher rigidity than the friction body 42, and the protrusion 70 protrudes from the second outer surface 66. A user's finger can hook onto, for example, a side surface 73 of the protrusion 70. Because the protrusion 70 has high rigidity, loss of torque applied by the user can be suppressed. The user can rotate the friction device 14 until the female thread 55 and the male thread 83 are sufficiently engaged. When the female thread 55 and the male thread 83 are sufficiently abutted, the end surface 81 of the barrel 11 and the second end 54 of the mounting member 41 come into contact with each other. The user may also pinch the protrusion 70 instead of the second outer surface 66.

[0074] Furthermore, when the friction device 14 is separated from the barrel 11, the substantially cylindrical friction device 14 may roll away and be lost. However, in this embodiment, the protrusion 70 protrudes from the second outer surface 66. Therefore, the protrusion 70 can come into contact with the ground, for example, and stop the friction device 14 from rolling away.

[0075] In the writing instrument 10 according to the first embodiment described above, the attachment member 41 has a female thread 55 that can be fitted with a male thread 83 provided on the writing instrument 10 while rotating about the central axis Ax, and a cylindrical first outer surface 52 that extends along the central axis Ax. The friction body 42 surrounds the attachment member 41 and is capable of generating frictional heat that thermally discolors the written mark of thermochromic ink. The friction body 42 has a second inner surface 65 in contact with the first outer surface 52 and a second outer surface 66 located on the opposite side of the second inner surface 65. The hook portion 43 has a protrusion 70 that protrudes from the second outer surface 66. When the friction device 14 is attached to the writing instrument 10, the engagement between the female thread 55 and the male thread 83 causes the friction body 42 to rotate. The friction body 42 can be gripped by a user, for example, during rotation. The hook portion 43 having the protrusion 70 can be caught by the user's finger that rotates the friction body 42. As a result, the hook portion 43 can suppress loss (waste) of torque applied by the user, which may be caused by, for example, elastic deformation of the friction body 42 or slippage between the second outer surface 66 and the user's finger, and can therefore suppress loosening of the engagement between the female screw 55 and the male screw 83. Therefore, the friction device 14 can be prevented from falling off the writing instrument 10 due to loosening of the engagement between the female screw 55 and the male screw 83. Furthermore, when the friction device 14 rolls, the protrusion 70 of the hook portion 43 can stop the friction device 14 from rolling. Therefore, the friction device 14 can be prevented from rolling and being lost.

[0076] The hook portion 43 is provided on the mounting member 41 and has a protrusion 70 that protrudes from the first outer surface 52. That is, the protrusion 70 has higher rigidity than the friction body 42. Therefore, the protrusion 70 is less likely to be elastically deformed by the user's finger getting caught on it. Therefore, the hook portion 43 can further suppress loss (waste) of torque applied by the user, and further suppress loosening of the engagement between the female thread 55 and the male thread 83. Furthermore, when the friction device 14 rolls, the protrusion 70 can stop the friction device 14 from rolling. Therefore, the friction device 14 can be prevented from rolling and being lost.

[0077] The writing instrument 10 has a friction device 14, a nib 33, and a barrel 11. The nib 33 is capable of ejecting thermochromic ink. The barrel 11 has a front end 11a where the nib 33 can be provided, and a rear end 11b where a male thread 83 is provided. In other words, one writing instrument 10 is provided with a nib 33 that can write thermochromic ink marks and a friction device 14 that can thermally change the color of the thermochromic ink marks. This allows one writing instrument 10 to write thermochromic ink marks and thermally change the color of the thermochromic ink marks.

[0078] (Second embodiment) The second embodiment will be described below with reference to Figures 5 to 8. In the following description of the embodiments, components having the same functions as components already described are given the same reference numerals as the components already described, and further description may be omitted. Furthermore, components given the same reference numerals do not necessarily have all the same functions and properties, and may have different functions and properties according to each embodiment.

[0079] Fig. 5 is a perspective view showing a friction device 100 according to a second embodiment. Fig. 6 is a perspective view showing the friction device 100 according to the second embodiment from a different direction than Fig. 5. Fig. 7 is a cross-sectional view showing the friction device 100 according to the second embodiment taken along line F7-F7 in Fig. 5. Fig. 8 is a cross-sectional view showing the friction device 100 according to the second embodiment taken along line F8-F8 in Fig. 5.

[0080] The friction device 100 of the second embodiment is attached to the rear end portion 11b of the barrel 11 or the end portion 13a of the cap 13, instead of the friction device 14 of the first embodiment. As shown in FIG. 8 , the friction device 100 of the second embodiment has an attachment member 101, a friction body 102, and a hook portion 103.

[0081] The mounting member 101 is made of, for example, synthetic resin or metal, similar to the mounting member 41 of the first embodiment. Like the mounting member 41, the mounting member 101 is provided with a through hole 50 and has a first inner surface 51, a first outer surface 52, a first end 53, a second end 54, and a female thread 55. However, the mounting member 101 is not limited to this example.

[0082] The friction body 102 is made of a low-wear elastic material, similar to the friction body 42 of the first embodiment. The rigidity of the friction body 102 is lower than the rigidity of the mounting member 101. Similar to the friction body 42, the friction body 102 has a peripheral wall 61 and a rear wall 62. However, the friction body 102 is not limited to this example.

[0083] 7, the mounting member 101 of the second embodiment further has an inner rib 110 instead of the protrusion 70. The inner rib 110 has two lateral ribs 111 and a rear rib 112. The lateral rib 111 is an example of a second protrusion.

[0084] The transverse ribs 111 protrude radially from the first outer surface 52 of the mounting member 101. The transverse ribs 111 are formed in the shape of plates extending in the axial direction. The multiple transverse ribs 111 are arranged around the first outer surface 52 at intervals. In other words, the multiple transverse ribs 111 are arranged circumferentially at intervals. In this embodiment, two transverse ribs 111 are arranged at equal intervals (every 180°) in the circumferential direction. Note that the number and intervals of the transverse ribs 111 are not limited to this example. For example, only one transverse rib 111 may protrude from the first outer surface 52.

[0085] The transverse rib 111 has a rear end 121, a front end 122, and two side surfaces 123 shown in Figure 6. The rear end 121 is the end of the transverse rib 111 in the rear direction Db. The front end 122 is the end of the transverse rib 111 in the forward direction Df. The side surface 123 is the end of the transverse rib 111 in the circumferential direction. The two side surfaces 123 face in opposite directions.

[0086] 7, the length of the transverse rib 111 in the axial direction is longer than the length of the mounting member 101 in the axial direction. The transverse rib 111 extends in the rear direction Db beyond the first end portion 53. Meanwhile, the front end portion 122 of the transverse rib 111 is positioned at approximately the same position as the second end portion 54 in the axial direction.

[0087] The radial length of the lateral ribs 111 is set, for example, to be approximately the same as the radial length (thickness) of the peripheral wall 61. The lateral ribs 111 do not protrude from the second outer surface 66 and are covered by the peripheral wall 61. However, the lateral ribs 111 are not limited to this example.

[0088] The rear rib 112 is located outside the through hole 50 and extends in a first direction D1 between the rear ends 121 of the two transverse ribs 111. The first direction D1 is a direction intersecting (orthogonal to) the axial direction and is one of the radial directions. That is, the end of the rear rib 112 in the first direction D1 is connected to the rear ends 121 of the transverse ribs 111. The rear rib 112 extends in the first direction D1 (radial direction) so as to pass through the central axis Ax and cross the through hole 50.

[0089] The rear rib 112 has a rear edge 131, a front edge 132, and two side surfaces 133 shown in FIG. 8. The rear edge 131 is the end of the rear rib 112 in the rear direction Db. The front edge 132 is the end of the rear rib 112 in the forward direction Df and faces the through-hole 50. A portion of the front edge 132 is connected to the first end 53. In other words, the rear rib 112 protrudes from the first end 53.

[0090] The side surface 133 is the end of the rear rib 112 in the second direction D2. The second direction D2 is perpendicular to the axial direction and perpendicular to the first direction D1. The two side surfaces 133 face in opposite directions. The side surface 133 of the rear rib 112 is continuous with the side surface 123 of the cross rib 111.

[0091] 8, the width W1 of the rear rib 112 in the second direction D2 is shorter than the diameter Di of the through-hole 50. Therefore, the rear rib 112 partially covers the through-hole 50 and partially exposes the through-hole 50.

[0092] 5, the hook portion 103 of the second embodiment has an outer rib 140. The outer rib 140 is formed integrally with the friction body 102. In other words, the friction body 102 has the outer rib 140 of the hook portion 103. In other words, the outer rib 140 is provided on the friction body 102.

[0093] The outer rib 140 covers the inner rib 110. In other words, the outer rib 140 contains the inner rib 110. The outer rib 140 has a plurality of horizontal ribs 141 and a rear rib 142. The horizontal rib 141 is an example of a first protrusion. The rear rib 142 is an example of a bridging portion.

[0094] The transverse ribs 141 protrude radially from the second outer surface 66 of the friction body 102. The transverse ribs 141 of the outer rib 140 cover the transverse ribs 111 of the inner rib 110. In other words, the transverse ribs 141 contain the transverse ribs 111. Therefore, the outer shape of the transverse ribs 141 is substantially similar to the outer shape of the transverse ribs 111. Note that the outer shape of the transverse ribs 141 and the outer shape of the transverse ribs 111 may be different.

[0095] The lateral rib 141 is formed in a plate shape extending in the axial direction. The multiple lateral ribs 141 are arranged at intervals around the second outer surface 66. In this embodiment, two lateral ribs 141 are arranged at equal intervals (every 180°) in the circumferential direction.

[0096] The transverse rib 141 has a rear end 151, a front end 152, and two side surfaces 153. The rear end 151 is the end of the transverse rib 141 in the rear direction Db. The front end 152 is the end of the transverse rib 141 in the forward direction Df. The front end 152 of the transverse rib 141 does not cover the front end 122 of the transverse rib 111 but exposes it. The side surface 153 is the end of the transverse rib 141 in the circumferential direction. The two side surfaces 153 face in opposite directions.

[0097] The length of the transverse rib 141 in the axial direction is longer than the distance in the axial direction between the second end 54 and the outer surface 68. The transverse rib 141 extends in the rear direction Db beyond the outer surface 68. Meanwhile, the front end 152 of the transverse rib 141 is positioned at approximately the same position as the second end 54 in the axial direction.

[0098] The rear rib 142 of the outer rib 140 covers the rear rib 112 of the inner rib 110. In other words, the rear rib 142 contains the rear rib 112. Therefore, the outer shape of the rear rib 142 is substantially similar to the outer shape of the rear rib 112. Note that the outer shape of the rear rib 142 and the outer shape of the rear rib 112 may be different.

[0099] The rear rib 142 is located outside the through holes 50, 69 and extends in the first direction D1 between the rear end portions 151 of the two transverse ribs 141. That is, the end portion of the rear rib 142 in the first direction D1 is connected to the rear end portions 151 of the transverse ribs 141. The rear rib 142 extends in the first direction D1 (radial direction) so as to pass through the central axis Ax and cross the through holes 50, 69.

[0100] As shown in FIG. 8 , the rear rib 142 has a rear end surface 161, a front end surface 162, and two side surfaces 163. The rear end surface 161 is an end of the rear rib 142 in the rear direction Db. The front end surface 162 is an end of the rear rib 142 in the forward direction Df and faces the through-holes 50 and 69. A portion of the front end surface 162 is connected to the outer surface 68. In other words, the rear rib 142 protrudes from the outer surface 68. Therefore, the rear rib 142 partially covers the first end 53 of the mounting member 101 via the rear wall 62 of the friction body 102. The front end surface 162 of the rear rib 142 does not cover the front edge 132 of the rear rib 112 but exposes it.

[0101] The side surface 163 is the end of the rear rib 112 in the second direction D2. The two side surfaces 163 face in opposite directions. The side surface 163 of the rear rib 142 is continuous with the side surface 153 of the cross rib 141.

[0102] The width W2 of the rear rib 142 in the second direction D2 is shorter than the diameter Di of each of the through holes 50, 69. Therefore, the rear rib 142 partially covers and partially exposes the through holes 50, 69. Furthermore, the width W2 of the rear rib 142 in the second direction D2 is shorter than the diameter of the second outer surface 66.

[0103] The thicknesses of the respective portions of the friction body 102 are different from one another. The thickness T3 of the rear rib 142 in the axial direction is longer than the thickness T4 of the rear wall 62 in the axial direction. The thickness T3 of the rear rib 142 is the distance between the rear end surface 161 of the rear rib 142 and the rear edge 131 of the rear rib 112.

[0104] When the friction device 100 is attached to the barrel 11, the female thread 55 of the attachment member 101 is fitted into the male thread 83 of the barrel 11, causing the friction device 100 to rotate around the central axis Ax. In this embodiment, the lateral rib 141 protrudes from the second outer surface 66. When the friction device 100 is attached, the user's fingers can hook onto the side surface 153 of the lateral rib 141. Therefore, the lateral rib 141 can suppress loss of torque applied by the user. Furthermore, when the friction device 100 is separated from the barrel 11, the lateral rib 141 can come into contact with, for example, the ground, and stop the friction device 100 from rolling.

[0105] Furthermore, when the friction device 100 thermally discolors handwriting, different parts of the friction body 102 are used depending on the range of handwriting to be thermally discolored. For example, the rear rib 142 is relatively small, so it can thermally discolor fine handwriting. Furthermore, the rear rib 142 is unlikely to obscure the handwriting that is the target of thermal discoloration, making it easier for the user to see the handwriting. On the other hand, the outer surface 68 of the rear wall 62 or the corner portion between the peripheral wall 61 and the rear wall 62 is relatively large, so it can efficiently thermally discolor a wide range of handwriting.

[0106] In the writing instrument 10 of the second embodiment described above, the mounting member 101 has a horizontal rib 111 protruding from the first outer surface 52. The hook portion 103 has a horizontal rib 141 that is provided on the friction body 102 and covers the horizontal rib 111. The horizontal rib 141 is smaller than the rear wall 62 of the friction body 102 on which the second outer surface 66 is provided. Therefore, the friction body 102 can more accurately thermocolorize handwriting in a desired range by using each part of the friction body 102 appropriately. For example, the horizontal rib 141 provided on the friction body 102 accurately thermocolorizes fine handwriting. On the other hand, the second outer surface 66 efficiently thermocolors handwriting in a wide range.

[0107] The mounting member 101 is provided with a through hole 50 extending along the central axis Ax. The mounting member 101 has a first end 53, where one end of the through hole 50 is open and is covered by the friction body 102, and a second end 54, where the other end of the through hole 50 is open and is located opposite the first end 53 and is exposed. The friction body 102 has a rear rib 142. The rear rib 142 is located outside the through hole 50, extends in a first direction D1 intersecting the axial direction along which the through hole 50 extends, partially covers the through hole 50 and the first end 53, and is connected to the transverse rib 141. The width of the rear rib 142 in a second direction D2 perpendicular to the axial direction and perpendicular to the first direction D1 is shorter than the diameter of the through hole 50. The rear rib 142 is smaller than the rear wall 62 of the friction body 102, where the second outer surface 66 is located. Therefore, by using each part of the friction body 102 appropriately, the friction body 102 can more accurately thermally discolor handwriting in a desired range. For example, the rear rib 142 allows fine handwriting to be accurately thermally discolored. The rear rib 142 covers the first end portion 53 and is therefore located at the end of the friction body 102. Therefore, when the friction device 100 thermally discolors fine handwriting, the user can easily visually recognize the handwriting. Furthermore, because the width of the rear rib 142 is shorter than the diameter of the through-hole 50, the rear rib 142 can be prevented from blocking the through-hole 50.

[0108] (Third embodiment) The third embodiment will be described below with reference to Fig. 9. Fig. 9 is a perspective view showing a friction device 200 according to the third embodiment.

[0109] The friction device 200 of the third embodiment is attached to the rear end portion 11b of the barrel 11 or the end portion 13a of the cap 13 in place of the friction device 14 of the first embodiment. As shown in FIG. 9 , the friction device 200 of the third embodiment has an attachment member 201, a friction body 202, and a hook portion 203.

[0110] The mounting member 201 is made of, for example, synthetic resin or metal, similar to the mounting member 41 of the first embodiment. Like the mounting member 41, the mounting member 201 is provided with a through hole 50 and has a first inner surface 51, a first outer surface 52, a first end 53, a second end 54, and a female thread 55. However, the mounting member 201 is not limited to this example.

[0111] The friction body 202 is made of a low-wear elastic material, similar to the friction body 42 of the first embodiment. The rigidity of the friction body 202 is lower than the rigidity of the mounting member 201. Similar to the friction body 42, the friction body 202 has a peripheral wall 61 and a rear wall 62. However, the friction body 202 is not limited to this example.

[0112] The hook portion 103 of the third embodiment has a plurality of concave surfaces 211. The concave surfaces 211 are formed integrally with the friction body 202. In other words, the friction body 202 has the concave surfaces 211 of the hook portion 203. In other words, the concave surfaces 211 are provided on the friction body 202.

[0113] The concave surfaces 211 are recessed from the second outer surface 66 of the friction body 202. The plurality of concave surfaces 211 are arranged at intervals around the second outer surface 66. In this embodiment, four concave surfaces 211 are arranged at equal intervals (every 90°) in the circumferential direction.

[0114] In the example of FIG. 9 , the concave surface 211 is a curved surface recessed from the second outer surface 66. However, the concave surface 211 is not limited to this example. For example, the concave surface 211 may be a flat surface, or may have a side surface facing approximately in the circumferential direction and a bottom surface facing approximately in the radial direction. Furthermore, the concave surface 211 may form (define, define) a groove extending approximately in the axial direction, for example. The friction body 202 is provided with a plurality of concave surfaces 211 each forming the groove, and thereby a plurality of the grooves are provided around the second outer surface 66, arranged at intervals from each other.

[0115] When the friction device 200 is attached to the barrel 11, the female thread 55 of the attachment member 201 is fitted into the male thread 83 of the barrel 11, causing the friction device 200 to rotate around the central axis Ax. In this embodiment, the concave surface 211 is recessed from the second outer surface 66. When the friction device 200 is attached, the user's fingers can be caught on the concave surface 211. Therefore, the concave surface 211 can suppress loss of torque applied by the user. Furthermore, when the friction device 200 is separated from the barrel 11, the edge of the concave surface 211 can stop the friction device 200 from rolling.

[0116] As in the third embodiment described above, the hook portions 43, 103, 203 are not limited to protrusions such as the protrusion 70 and the horizontal rib 141, and may have the concave surface 211. Furthermore, although the concave surface 211 is provided on the friction body 102 in the third embodiment, the concave surface may be provided on the mounting member 101.

[0117] In the above embodiment, the male screw 83 is an example of a first screw, and the female screw 55 is an example of a second screw. However, the female screw may be an example of a first screw, and the male screw may be an example of a second screw.

[0118] In the above description, suppression is defined as, for example, preventing an event, action, or influence from occurring, or reducing the degree of an event, action, or influence. Also, in the above description, restriction is defined as, for example, preventing movement or rotation, or allowing movement or rotation within a predetermined range and preventing movement or rotation beyond the predetermined range.

[0119] The above-described embodiments of the present invention do not limit the scope of the invention, but are merely examples within the scope of the invention. Some embodiments of the present invention may be modified, omitted, or added to the above-described embodiments, for example, with respect to at least part of the specific applications, structures, shapes, actions, and effects, without departing from the spirit of the invention. [Explanation of symbols]

[0120] 10...writing implement, 11...barrel, 11a...front end, 11b...rear end, 14...friction device, 32...thermochromic ink, 41...mounting member, 42...friction body, 43...hook portion, 50...through hole, 52...first outer surface, 53...first end, 54...second end, 55...female thread, 65...second inner surface, 66...second outer surface, 70...protrusion, 83...male thread, 100...friction device, 101...mounting member, 102...friction body, 103...hook portion, 111...horizontal rib, 141...horizontal rib, 142...rear rib, 200...friction device, 201...mounting member, 202...friction body, 203...hook portion, 211...concave surface, Ax...central axis, D1...first direction, D2...second direction, W2...width, Di...diameter.

Claims

1. an attachment member having a second screw that can be engaged with a first screw provided on the writing instrument while rotating about a rotation axis, and a cylindrical first outer surface that extends along the rotation axis; a friction body having a peripheral wall surrounding the mounting member, an inner surface provided on the peripheral wall and in contact with the first outer surface, and a second outer surface provided on the peripheral wall and positioned opposite the inner surface, the friction body being capable of generating frictional heat that thermally discolors handwriting of thermochromic ink; a hook portion provided on the mounting member and having a protrusion protruding from the first outer surface and protruding from the second outer surface; Equipped with an end portion of the second outer surface in a first axial direction along the rotation axis is located on the first axial side relative to an end portion of the projection in a second axial direction opposite to the first axial direction; Friction tool.

2. The protrusion penetrates the peripheral wall and protrudes from the second outer surface, and is exposed to the outside of the friction body outside the second outer surface. The friction device of claim 1.

3. The hanging portion has an outer protrusion that is provided on the friction body and covers the protrusion, the protrusion has an end surface in a direction in which the protrusion protrudes from the first outer surface, and two side surfaces provided at both ends of the protrusion around the rotation axis, the outer protrusion covers the end surface and the two side surfaces; The friction device of claim 1.

4. the mounting member has a through hole extending along the rotation axis and opening at an end of the mounting member in the first axial direction and at an end of the mounting member in the second axial direction, so that the end of the mounting member in the first axial direction is exposed; the friction body has a bridge portion that is located outside the through hole, extends in a first direction intersecting the first axial direction, partially covers the through hole and an end of the mounting member in the second axial direction, is connected to the outer protrusion, and has a width in a second direction perpendicular to the first axial direction and perpendicular to the first direction that is shorter than a diameter of the through hole; The friction device according to claim 3.

5. A friction device according to any one of claims 1 to 4; a pen tip capable of ejecting the thermochromic ink; a barrel having a front end portion to which the pen tip can be attached and a rear end portion to which the first screw is attached; A writing instrument comprising:

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