Mounting structure for writing implement and writing implement

Abstract

An attachment structure in a writing tool provided with a first component and a second component inserted into an insertion hole provided at an end of the first component. The second component is provided with a small-diameter part, a large-diameter part provided in front of the small-diameter part, and a first outer step part provided between the small-diameter part and the large-diameter part. The insertion hole is provided with a small-diameter hole part and an inner step part provided in front of the small-diameter hole part. The small-diameter part is inserted or loosely inserted into the small-diameter hole part. The first outer step part contacts the inner step part. The small-diameter hole part is provided with a barb part protruding from an inner surface of the small-diameter hole part. The barb part is deformable when contacting the small-diameter part during insertion of the second component.

Description

[Technical Field]

[0001] The present invention relates to a mounting structure for a writing instrument. and writing implements Regarding. [Background technology]

[0002] Patent document 1 discloses a pen core locking structure in which a pen core is inserted and fixed through an opening at the tip of the barrel, in which protrusions with a mountain-shaped cross section are provided at regular intervals in the longitudinal direction around the entire circumference of a pen core holding hole with a circular cross section at the tip of the barrel, and the height of the protrusions increases toward the rear.

[0003] According to this pen core locking structure, when the pen core has a circular or elliptical cross section, the rear peak of the ridge bites into the pen core to lock it in place, and when the cross section is rectangular such as square or rectangular, the adjacent sloping surfaces of adjacent ridges clamp the pen core near each ridge line, locking it in place, so the pen core can be locked without having to be processed with steps or cut grooves or the like on the pen core. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 1-161078 Summary of the Invention [Problem to be solved by the invention]

[0005] In the configuration disclosed in Patent Document 1, when the pen core (second part) is inserted from the tip of the barrel (first part), the tip is pressed into the pen core with the rear peak of the ridge biting into it. This requires a large force to insert the pen core, which can make it difficult to easily insert the pen core into the tip of the barrel.

[0006] Furthermore, in the configuration disclosed in Patent Document 1, the rear peaks of the ridges are pressed into the outer surface of the pen core, leaving scratches that extend in the axial direction on the outer surface of the pen core. As a result, when a force is applied to the pen core in the forward axial direction (i.e., a force in the direction that causes the pen tip to come out), the desired locking performance cannot be achieved, and there is a risk that the pen tip will easily come out.

[0007] The present invention was made in consideration of the above findings, and its purpose is to provide an attachment structure for a writing instrument that allows parts to be easily inserted and attached, but prevents the parts from falling out once inserted. [Means for solving the problem]

[0008] The mounting structure of the present invention is an mounting structure for a writing instrument comprising a first part and a second part inserted into an insertion hole provided at the end of the first part, wherein the second part comprises a small diameter portion, a large diameter portion provided in front of the small diameter portion, and a first outer step portion provided between the small diameter portion and the large diameter portion, the insertion hole comprises a small diameter hole portion and an inner step portion provided in front of the small diameter hole portion, the small diameter portion is inserted or loosely inserted into the small diameter hole portion, the first outer step portion and the inner step portion abut against each other, the small diameter hole portion comprises a barb portion protruding from the inner surface of the small diameter hole portion, and the barb portion is deformable when the small diameter portion comes into contact with the barb portion when the second part is inserted.

[0009] According to the present invention, the barb portion is deformable when the small diameter portion of the second part comes into contact with the barb portion during insertion of the second part, so that the second part can be inserted smoothly without significant resistance. On the other hand, if a forward axial force (i.e., a force in the direction that causes the second part to come out) is applied to the second part after insertion of the second part, the barb portion attempts to return to its state before the second part was inserted (before deformation), so that the barb portion bites into the outer surface of the small diameter portion of the second part and securely locks the second part. In other words, the second part is easily inserted, and the second part will not come out after insertion.

[0010] Furthermore, according to the present invention, the inner step functions as a stopper that can position the second component when it is inserted, making it easy to insert the second component into the desired position. Furthermore, even if the user applies excessive force to the second component, the second component will not be buried in the first component.

[0011] Preferably, the barb portion is provided at the rear end of the inner surface of the small diameter hole portion, which allows the small diameter hole portion to function as a guide for inserting the small diameter portion into the small diameter hole portion, making it easier to insert the second component.

[0012] Preferably, the insertion hole further includes a large-diameter hole portion provided in front of the inner step portion, and the large-diameter portion is inserted into or loosely fitted into the large-diameter hole portion, thereby enabling a more forward portion of the second component to be clamped, thereby stabilizing the second component.

[0013] Preferably, a plurality of the barbs are arranged at equal intervals around the circumference of the small diameter hole, so that the barbs bite into the outer surface of the second component at equal intervals around the circumference, thereby enabling the second component to be more securely locked.

[0014] Preferably, the cross section of the tip of the barb is rounded, which makes it possible to easily form the barb.

[0015] Preferably, the second part has a locking groove behind the first outer step and a second outer step at the rear end of the locking groove, and the barb is locked with the second outer step to prevent the second part from coming off in the axial direction. As a result, if a force in the axial direction (i.e., a force in the direction that would cause the second part to come off) is applied to the second part after the second part is inserted, a force acts on the barb to return it to its pre-tilt state. At this time, the barb gets caught on the second outer step provided on the outer surface of the small diameter part, more reliably preventing the second part from coming off after the second part is inserted.

[0016] Preferably, the first component is a writing instrument body, the second component is a pen tip, and the insertion hole is provided in the front of the writing instrument body. This allows the pen tip and the ink reservoir to be connected without connection failure, allowing ink to be smoothly supplied from the ink reservoir to the pen tip. Furthermore, even if a user applies excessive pressure to the pen tip while using the writing instrument, the pen tip will not sink into the writing instrument.

[0017] Preferably, the first component is the barrel or cap of the writing instrument, the second component is a soft member, and the insertion hole is provided at the rear end of the barrel or the closed end of the cap, so that even if a user applies excessive force to the soft member while using it, the soft member will not sink into the writing instrument. [Effects of the Invention]

[0018] According to the present invention, components can be easily inserted and attached, and once inserted, the components will not come off. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic vertical cross-sectional view of a writing instrument according to a first embodiment of the present invention. [Figure 2] FIG. 10 is an enlarged longitudinal cross-sectional view of a main part showing the pen tip insertion process of the present invention, illustrating the state before the pen tip is inserted. [Figure 3] 10 is an enlarged longitudinal cross-sectional view of a main part showing the pen tip insertion process of the present invention, and shows the state during pen tip insertion. FIG. [Figure 4] 10 is an enlarged longitudinal cross-sectional view of a main part showing the pen tip insertion process of the present invention, and shows the state after the pen tip has been inserted. FIG. [Figure 5] FIG. 1 is a cross-sectional perspective view of a barrel according to a first embodiment of the present invention, showing the state before a pen tip is inserted. [Figure 6] 3 is a cross-sectional view of the barrel taken along line AA in FIG. 2, showing the cross-sectional shape of a barb portion of the barrel in the first embodiment of the present invention. FIG. [Figure 7]3 is a cross-sectional view of the barrel taken along line AA in FIG. 2, showing the cross-sectional shape of a barb portion of the barrel in a second embodiment of the present invention. FIG. [Figure 8] FIG. 11 is an enlarged longitudinal cross-sectional view of the essential parts of a third embodiment of the present invention, showing the state after the pen tip has been inserted. [Figure 9] FIG. 10 is an enlarged longitudinal cross-sectional view of the essential parts of a fourth embodiment of the present invention, showing the state after the pen tip has been inserted. [Figure 10] FIG. 10 is a schematic vertical cross-sectional view of a writing instrument according to a fifth embodiment of the present invention. [Figure 11] 10 is an enlarged longitudinal cross-sectional view of a main part showing the insertion and attachment process of the soft member of the present invention, showing the state before the soft member is inserted and attached. FIG. [Figure 12] 10 is an enlarged longitudinal cross-sectional view of a main part showing the inserting and attaching process of the soft member of the present invention, showing the state during the insertion and attachment of the soft member. FIG. [Figure 13] 10 is an enlarged longitudinal cross-sectional view of a main part showing the inserting and attaching step of the soft member of the present invention, showing the state after the soft member has been inserted and attached. FIG. [Figure 14] FIG. 10 is a cross-sectional perspective view of a barrel according to a fifth embodiment of the present invention, showing the state before the soft member is inserted. [Figure 15] 12 is a cross-sectional view of the barrel taken along line BB in FIG. 11, showing the cross-sectional shape of a barb portion of the barrel in the fifth embodiment of the present invention. FIG. [Figure 16] 12 is a cross-sectional view of the barrel taken along line BB in FIG. 11, showing the cross-sectional shape of a barb portion of the barrel in the sixth embodiment of the present invention. FIG. [Figure 17] FIG. 13 is an enlarged longitudinal cross-sectional view of a main part showing a state after the soft member has been inserted in a seventh embodiment of the present invention. [Figure 18] FIG. 13 is an enlarged longitudinal cross-sectional view of a main part of an eighth embodiment of the present invention, showing a state after the soft member has been inserted. [Figure 19] FIG. 13 is a schematic vertical cross-sectional view of a portion of a writing instrument according to a ninth embodiment of the present invention. [Figure 20] FIG. 22 is a schematic vertical cross-sectional view of a portion of a writing instrument according to a tenth embodiment of the present invention. [Figure 21] FIG. 22 is a schematic vertical cross-sectional view of a portion of a writing instrument according to an eleventh embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] First, first to fourth embodiments of the present invention will be described below with reference to the drawings. In the pen tip attachment structures of the first to fourth embodiments, "front" refers to the pen tip 12 side of the writing implement, and "rear" refers to the opposite side. In the pen tip, "front" refers to the writing part 121 side, and "rear" refers to the opposite side.

[0021] Fig. 1 is a schematic vertical cross-sectional view of a writing instrument 10 according to the present invention, showing the state in which a cap 14 is attached. Figs. 2 to 4 are enlarged vertical cross-sectional views of the essential parts showing the pen tip insertion process of the present invention, showing the steps from before the pen tip is inserted to after the pen tip is inserted.

[0022] Fig. 5 is a cross-sectional perspective view of barrel 11 in the first embodiment of the present invention, showing the state before the pen tip is inserted. Figs. 6 and 7 are cross-sectional views of barrel 11 taken along line AA in Fig. 2, showing the cross-sectional shape of barb portion 115 of barrel 11 in the first and second embodiments of the present invention.

[0023] Fig. 8 is an enlarged vertical cross-sectional view of a main part of a third embodiment of the present invention, showing the state after the pen tip has been inserted, which differs from the other embodiments in the shape of the outer surface of the pen tip 12. Fig. 9 is an enlarged vertical cross-sectional view of a main part of a fourth embodiment of the present invention, showing the state after the pen tip has been inserted, which differs from the other embodiments in the shape of the outer surface of the pen tip 12 and the part forward of the small diameter hole 113 of the barrel 11.

[0024] First Embodiment The present invention provides a nib attachment structure in which a nib 12 (second component) is inserted into a nib insertion hole 111 (insertion hole) provided in the front part of a writing instrument 10 body (first component). The writing instrument 10 of this embodiment shown in FIG. 1 mainly comprises a cap 14, a nib 12, an ink occlusion body 13, and a barrel 11. The nib 12 is inserted into the front end of the barrel 11, and the ink occlusion body 13 is housed inside. The cap 14 may be provided with an airtight member 15 inside to prevent ink from evaporating from the nib 12. The nib 12 is inserted into the nib insertion hole 111 of the barrel 11 (front barrel 11a). In addition, the front shaft 11a and the rear shaft 11b may be detachably engaged with each other so that the ink occlusion body 13 can be replaced or ink can be replenished in the ink occlusion body 13 with the front shaft 11a removed from the rear shaft 11b.

[0025] When the writing instrument 10 is a thermochromic writing instrument that contains thermochromic ink, it may further include a soft member 16. The soft member 16 rubs the handwriting of the thermochromic ink, and the frictional heat generated at that time can thermally change the color of the handwriting of the thermochromic ink.

[0026] <Shaft tube> As shown in FIG. 1 , the barrel 11 is a bottomed cylindrical body with one open end and the other closed end, manufactured by injection molding or extrusion molding of synthetic resin. Examples of the synthetic resin material include polypropylene, polyethylene, polystyrene, polycarbonate, polyethylene terephthalate, polyacetal, acrylic, nylon, acrylonitrile-styrene copolymer resin (AS resin), and acrylonitrile-butadiene-styrene copolymer resin (ABS resin). The barrel 11 comprises a front barrel 11a and a rear barrel 11b, which are axially locked together to prevent disengagement. The front barrel 11a comprises a nib insertion hole 111, a flange, and a fitting portion. The large-diameter portion 122 of the nib 12 is inserted into the nib insertion hole 111. The flange is axially abuttable against the end of the opening of the rear barrel 11b. The fitting portion can be axially locked with the fitted portion on the inner surface of the opening of the rear axle 11b to prevent it from coming loose, and a first annular seal portion is formed on the outer surface of the fitting portion, which hermetically fits with a second annular seal portion on the inner surface of the fitted portion of the rear axle 11b.

[0027] 2, the inner surface of the pen nib insertion hole 111 is provided with a large diameter hole portion 112 on the opening side, a small diameter hole portion 113 provided behind the large diameter hole portion 112, and an inner step portion 114 that is perpendicular to the axis and provided between the large diameter hole portion 112 and the small diameter hole portion 113. The large diameter portion 122 of the pen nib 12 is inserted or loosely inserted into the large diameter hole portion 112. The small diameter portion 123 of the pen nib 12 is inserted or loosely inserted into the small diameter hole portion 113.

[0028] The small diameter hole 113 has a barb 115 that protrudes radially inward from the inner surface of the small diameter hole 113. As shown in FIG. 3, the barb 115 is deformable when the small diameter portion 123 comes into contact with it when the pen nib is inserted. That is, in this embodiment, the barb 115 is tilted axially rearward by the outer surface of the small diameter portion 123 of the pen nib 12 as the pen nib 12 is inserted. This allows the small diameter portion 123 to be easily inserted. That is, there is no significant resistance when the pen nib 12 is inserted, and the pen nib 12 can be inserted smoothly.

[0029] On the other hand, if a force in the forward axial direction (i.e., a force in the direction that causes the pen tip 12 to come out) is applied to the pen tip 12 after the pen tip 12 has been inserted (see FIG. 4), a force acts on the barb 115, causing it to return to the state it was in before it was tilted. In other words, the barb 115 tries to return to the state it was in before the pen tip 12 was inserted (before the barb 115 was deformed: see FIG. 2). This causes the barb 115 to bite into the outer surface of the small diameter portion 123 of the pen tip 12, securely locking the pen tip 12. In other words, the pen tip 12 is easy to insert, and the pen tip 12 will not come out after insertion.

[0030] 2, in this embodiment, the barb portion 115 is provided at the rear end of the inner surface of the small diameter hole portion 113. This allows the small diameter hole portion 113 to function as a guide for inserting the small diameter portion 123, making it easier to insert the small diameter portion 123 into the small diameter hole portion 113 and allowing the pen tip 12 to be inserted and attached more easily.

[0031] As shown in FIG. 5 or FIG. 6, in the present embodiment, a plurality of return portions 115 are arranged at equal intervals in the circumferential direction in the small-diameter hole portion 113, and the cross-section of the radially inner tip portion of the return portion 115 is in an R shape. However, the return portions 115 may be arranged at unequal intervals. Also, at least one return portion 115 may be formed as long as it bites into the outer surface of the small-diameter portion 123. The return portion 115 in the present embodiment has an axial thickness t of 0.1 mm, a protruding length L in the axial inward direction from the small-diameter hole portion of 0.5 mm, and a circumferential width W of 0.6 mm in the state before the pen tip 12 is inserted as shown in FIG. 2. Preferably, 0.01 mm < t < 1.0 mm, 0.1 mm < W < 3.0 mm, and 0.1 mm < L < 2.0 mm are satisfied. By setting the dimensions of the return portion within these ranges, the insertion of the pen tip 12 can be made easier, and the pen tip 12 will not come out after insertion.

[0032] On the inner surfaces of the large-diameter hole portion 112 and the small-diameter hole portion 113, a plurality of (specifically, eight) air circulation grooves 117 extending in the axial direction are arranged at equal intervals. By means of the air circulation grooves 117, an axial air circulation path is formed between the outer surface of the pen tip 12 and the inner surface of the shaft cylinder 11. As a result, air circulation becomes smooth, and ink is smoothly supplied from the ink reservoir 13 to the pen tip 12.

[0033] As shown in FIG. 4, when the pen tip 12 is inserted, the inner step portion 114 is abutted by a first outer step portion 124 of the pen tip 12 described later. As a result, since the inner step portion 114 functions as a stopper capable of positioning the pen tip 12 during insertion, the pen tip 12 can be easily inserted into a desired position. Also, the pen tip 12 and the ink reservoir 13 are connected without causing a connection failure, and ink is smoothly supplied from the ink reservoir 13 to the pen tip 12. Further, even if the user applies excessive writing pressure to the pen tip 12 during use of the writing instrument, the pen tip 12 will not be buried in the writing instrument.

[0034] The writing instrument 10 of the present invention can be of a type in which an ink occlusion body 13 that holds ink is housed within the barrel 11, or of a type in which ink that is directly housed within the barrel 11 is guided to the pen tip 12 via the ink occlusion body 13. If necessary, an ink reservoir member (for example, a comb-groove-shaped ink reservoir member) that temporarily holds excess ink in response to changes in the internal pressure of the ink tank, or a guide member that guides ink from the ink occlusion body 13 that holds ink to the pen tip 12 can also be provided. Furthermore, the writing instrument may be of either a cap type or a pen tip retractable type (knock type).

[0035] <Pen tip> The pen tip 12 has on its outer surface a large diameter portion 122, a small diameter portion 123 provided behind the large diameter portion 122, and a first outer step 124 provided between the large diameter portion 122 and the small diameter portion 123. The large diameter portion 122 is cylindrical and has a writing portion 121 at its tip. The small diameter portion 123 is also cylindrical and is connected to the ink occlusion body 13. The first outer step 124 abuts against the inner step 114 of the pen tip insertion hole 111 when the pen tip 12 is inserted.

[0036] One end of the nib 12 protrudes forward from the front opening of the barrel 11 as the writing part 121. The other end (small diameter part 123) of the nib 12 is connected to the front end of the ink occlusion body 13 in a piercing manner. For example, as shown in FIG. 3, the writing part 121 is processed into a chisel shape. However, the writing part 121 is not limited to a chisel shape and may be processed into other shapes depending on the purpose, such as a bullet shape, a rectangle, a square prism shape, or a plate shape. The form of the writing instrument 10 of the present invention is not limited to the example shown in the drawings, and may be a double-ended writing instrument in which nibs 12 of different shapes are attached to both ends of the ink occlusion body 13.

[0037] The nib 12 is made of a resin-processed fiber (for example, a resin-processed polyester fiber), one end of which protrudes to the outside as the writing part 121, and the other end of which is connected in a piercing manner to one end of the ink occlusion body 13. Of course, the nib 12 can be any nib as long as it allows ink to flow through it, and specific examples include a fiber nib that is a fusion-processed product of heat-fusible fibers, a felt nib made of felt, a plastic nib in which multiple resin threads (monofilaments formed by extrusion molding of synthetic resin) are fused together to form an axial ink flow path inside, a nib (porous tip) made of a porous body with open bubbles of synthetic resin, a calligraphy nib, and other nibs that utilize capillary force. The pen tip 12 may be a tip formed by deforming the vicinity of the tip of a metal pipe by pressing inward from the outer surface and holding a ball in a ball-holding portion, or a tip formed by cutting a metal material with a drill or the like and holding a ball in a ball-holding portion, or a metal or plastic tip with a resin ball seat inside. The ball may be made of cemented carbide, stainless steel, ruby, ceramic, resin, rubber, or the like, and have a diameter of about 0.3 to 3.0 mm, preferably 0.3 to 1.5 mm, and more preferably 0.4 to 1.0 mm.

[0038] <Ink occluder> The ink occlusion body 13 may be any material that can be impregnated with ink, and specific examples thereof include a fiber bundle processed body (for example, a heat-fused fiber bundle processed body, a resin-processed fiber bundle processed body, a resin-processed felt body, or a needle-punched felt body) or a porous body (for example, an open-cell foam body made of synthetic resin such as a sponge). The outer peripheral surface of the ink occlusion body 13 may be covered with a synthetic resin film.

[0039] As shown in Figures 1 and 2, the front end surface of ink occlusion body 13 abuts in the axial direction against abutment wall 116 provided on front barrel 11a. The rear end surface of ink occlusion body 13 abuts in the axial direction against a second abutment wall (not shown) provided on rear barrel 11b. The longitudinal dimension of ink occlusion body 13 is preferably set to be larger than the longitudinal dimension between abutment wall 116 and the second abutment wall. In this way, ink occlusion body 13 inside barrel 11 is sandwiched in the axial direction between abutment wall 116 and the second abutment wall, ensuring stable writing performance.

[0040] <Soft materials> 1, in this embodiment, the soft member 16 is axially engaged with the top of the cap 14 to prevent it from coming off. However, the attachment structure and attachment position of the soft member 16 are not limited to this embodiment. For example, the soft member 16 made of an elastic material may be attached to the outer surface of the rear end of the barrel 11 by press-fitting, engagement, screwing, fitting, bonding, two-color molding, or the like. Alternatively, the barrel 11 or the cap 14 may be entirely formed integrally from an elastic material.

[0041] The elastic synthetic resin that constitutes the soft member 16 is preferably made of a low-wear elastic material that generates almost no wear debris (eraser debris) during friction, rather than a high-wear elastic material (such as an eraser).

[0042] The elastic material constituting the soft member 16 is preferably, for example, an elastic synthetic resin (rubber, elastomer), such as silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin (styrene-ethylene-butylene-styrene copolymer), fluorine-based resin, chloroprene resin, nitrile resin, polyester-based resin, ethylene propylene diene rubber (EPDM), or a mixture of two or more types of rubber elastic materials, and a mixture of a rubber elastic material and a synthetic resin.

[0043] <Ink> In this embodiment, the ink contained in the ink occlusion body 13 is a thermochromic ink. The thermochromic ink is preferably a reversible thermochromic ink. The reversible thermochromic ink may be of various types, either alone or in combination, such as a thermal decolorization type that is decolorized from a colored state by heating, a color memory retention type that alternately retains a colored state or a decolorized state within a specific temperature range, or 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.

[0044] The coloring material contained in the reversible thermochromic ink is preferably, for example, a reversible thermochromic pigment in which a reversible thermochromic composition containing at least the three essential components of (i) an electron-donating color-forming organic compound, (ii) an electron-accepting compound, and (iii) a reaction medium that determines the temperature at which the reaction (coloring reaction) in which the two compounds chemically bond with each other occurs is encapsulated in microcapsules.

[0045] The ink used in the present invention is not limited to thermochromic ink, and ink compositions other than thermochromic ink can also be used. For example, writing ink, correction fluid, liquid glue, cosmetic liquid, etc. may be selected appropriately depending on the application of the liquid ejection device. The writing ink is not particularly limited to oil-based ink or water-based ink.

[0046] Second Embodiment 7 is a cross-sectional view of the barrel 11 taken along line AA in FIG. 2, illustrating the shape of the barb 115 of the barrel 11 in a second embodiment of the present invention. In the second embodiment of the present invention, the cross-sectional shape of the barb 115 is different from that in the first embodiment. Specifically, the cross-section of the radially inner tip portion is sharp-pointed.

[0047] The other configurations of the second embodiment are substantially the same as those of the first embodiment, and therefore detailed description thereof will be omitted. As shown in Figure 7, according to this embodiment, the barbs 115 dig into the outer surface of the nib 12 at equal intervals around the circumference, enabling the nib 12 to be more securely locked. Furthermore, because the cross section of the radially inner tip of the barbs 115 is sharp-pointed, the barbs 115 dig deeper into the outer surface of the nib 12, and the nib 12 is more firmly locked in the axial direction.

[0048] However, the cross section of the tip of barb portion 115 is not limited to a sharp shape or the aforementioned R shape, and may be other shapes according to the pen tip, such as a rectangular shape, an inverted R shape with a radially inward tip recessed, etc. Also, barb portion 115 may be a burr formed when resin gets into the gap between the mating surfaces of the mold (pin) when barrel 11 is manufactured by injection molding.

[0049] Third Embodiment Figure 8 is an enlarged longitudinal cross-sectional view of essential parts of a third embodiment of the present invention, showing the state after the pen tip 12 has been inserted. In the third embodiment of the present invention, the shape of the pen tip 12 rearward of the first outer step 124 differs from that of the first embodiment. Specifically, as shown in Figure 8, the pen tip 12 has a locking groove 125 rearward of the first outer step 124 and a second outer step 126 at the rear end of the locking groove 125, and the barb 115 is locked in the second outer step 126, preventing the pen tip 12 from slipping out in the axial direction. The locking groove 125 is preferably formed circumferentially on the small diameter portion 123.

[0050] The other configurations of the third embodiment are substantially the same as those of the first embodiment, and therefore detailed description thereof will be omitted. According to this embodiment, as in the first embodiment, when a force in the axial direction (i.e., a force in the direction in which the nib 12 is removed) is applied to the nib 12 after it has been inserted, a force acts on the barb portion 115 to return it to its pre-tilt state. At this time, as shown in FIG. 8 , the barb portion 115 engages with the second outer step 126 provided on the outer surface of the small diameter portion 123, more reliably preventing the nib 12 from being removed after it has been inserted. Furthermore, because the locking groove 125 is formed circumferentially on the small diameter portion 123, positioning of the nib 12 in the rotational direction is not required when inserting the nib 12 into the barrel 11, and the nib 12 can be easily inserted.

[0051] <Fourth embodiment> Figure 9 is an enlarged vertical cross-sectional view of the main part of the fourth embodiment of the present invention, showing the state after the pen tip 12 has been inserted. In the fourth embodiment of the present invention, the shape of the barrel 11 forward of the small diameter hole portion 113 is different from that of the third embodiment. Specifically, as shown in Figure 9, the large diameter hole portion of the barrel 11 is omitted, and an inner step portion 114 is provided at the front end of the barrel.

[0052] Furthermore, in the fourth embodiment of the present invention, the outer shape of the nib 12 is different from that of the third embodiment. Specifically, as shown in Fig. 9, the nib 12 has a locking groove 125 on the surface of the small-diameter portion behind the outer step, and a second outer step 126 at the rear end of the locking groove 125, and the writing part 121 is bullet-shaped. Furthermore, when the first outer step 124 and the inner step 114 of the nib 12 abut against each other, an air circulation hole 127 is formed between the first outer step 124 and the inner step. This allows for smooth air circulation, allowing ink to be smoothly supplied from the ink occlusion body 13 to the nib 12.

[0053] The other configurations of the fourth embodiment are substantially the same as those of the third embodiment, and therefore detailed description thereof will be omitted. According to this embodiment, the pen tip 12 can be clamped further forward, closer to the writing part 121, allowing for stable writing.

[0054] The pen tip mounting structure configured as above operates as follows.

[0055] The nib mounting structure of the present invention is a nib mounting structure in which a nib 12 is inserted into a nib insertion hole 111 provided in the front part of the body of a writing instrument 10, and the nib 12 has a small diameter portion 123, a large diameter portion 122 provided in front of the small diameter portion 123, and a first outer step portion 124 provided between the small diameter portion 123 and the large diameter portion 122, the nib insertion hole 111 has a small diameter hole portion 113 and an inner step portion 114 provided in front of the small diameter hole portion 113, the small diameter portion 123 is inserted or loosely inserted into the small diameter hole portion 113, and the first outer step portion 124 and the inner step portion 114 abut against each other, and the small diameter hole portion 113 has a barb portion 115 protruding from the inner surface of the small diameter hole portion 113, and the barb portion 115 can be deformed by contact with the small diameter portion 123 when the nib is inserted.

[0056] According to the present invention, the barb portion 115 can be deformed by contact with the small diameter portion 123 of the pen tip 12 when the pen tip is inserted, so that the pen tip 12 can be inserted smoothly without much resistance. On the other hand, if a force in the forward axial direction (i.e., a force in the direction that causes the pen tip 12 to come out) is applied to the pen tip 12 after the pen tip is inserted, the barb portion 115 will attempt to return to the state it was in before the pen tip was inserted (before deformation), so the barb portion 115 will bite into the outer surface of the small diameter portion of the pen tip 12 and securely lock the pen tip 12. In other words, the pen tip 12 is easy to insert, and the pen tip 12 will not come out after insertion.

[0057] Furthermore, according to the present invention, the inner step 114 functions as a stopper that allows positioning when the pen tip is inserted, making it possible to easily insert the pen tip 12 into the desired position. Furthermore, the pen tip 12 and the ink occlusion body 13 are connected without connection failure, and ink is smoothly supplied from the ink occlusion body 13 to the pen tip 12. Furthermore, even if the user applies excessive writing pressure to the pen tip 12 while using the writing instrument 10, the pen tip 12 will not sink into the writing instrument 10.

[0058] Preferably, barb portion 115 is provided at the rear end of the inner surface of small diameter hole portion 113. This allows small diameter hole portion 113 to function as a guide for inserting small diameter portion 123, making it easier to insert small diameter portion 123 into small diameter hole portion 113 and allowing pen tip 12 to be inserted and attached more easily.

[0059] Preferably, the pen tip insertion hole 111 further includes a large diameter hole portion 112 provided in front of the inner step portion 114, and the large diameter portion 122 is inserted or loosely fitted into the large diameter hole portion 112. This allows the pen tip 12 to be clamped further forward, allowing for stable writing.

[0060] Preferably, a plurality of barbs 115 are arranged at equal intervals around the circumference of small-diameter hole 113, and the cross section of the tip of each barb 115 is rounded. This allows barbs 115 to dig into the outer surface of nib 12 at equal intervals around the circumference, more reliably locking nib 12. Furthermore, because the cross section of the tip of each barb 115 is rounded, barbs 115 can be easily formed.

[0061] Preferably, the nib 12 has a locking groove 125 behind the first outer step 124 and a second outer step 126 at the rear end of the locking groove 125, and the barb 115 is locked in the second outer step 126, preventing the nib 12 from coming off in the axial direction. As a result, if a force in the forward axial direction (i.e., a force in the direction that causes the nib 12 to come off) is applied to the nib 12 after the nib is inserted, a force acts on the barb 115 to return it to its state before tilting. At this time, the barb 115 gets caught on the second outer step 126 provided on the outer surface of the small diameter portion, more reliably preventing the nib 12 from coming off after the nib is inserted.

[0062] The present invention also covers only the barrel 11 of the writing instrument 10. That is, the barrel 11 of the writing instrument 10 has a pen tip insertion hole 111 at the front end into which the pen tip 12 is inserted, and the outer surface of the pen tip 12 has a large diameter portion 122, a small diameter portion 123 provided behind the large diameter portion 122, and a first outer step portion 124 provided between the large diameter portion 122 and the small diameter portion 123, and the inner surface of the pen tip insertion hole 111 has a large diameter hole portion 112, a small diameter hole portion 113 provided behind the large diameter hole portion 112, and a first outer step portion 124 between the large diameter hole portion 112 and the small diameter hole portion 123. The barrel 11 of the writing instrument 10 has an inner step 114 provided between the large diameter portion 122 and the small diameter portion 123, the large diameter portion 122 is inserted into the large diameter hole portion 112, the small diameter portion 123 is inserted or loosely inserted into the small diameter hole portion 113, the first outer step 124 and the inner step 114 are in contact, the small diameter hole portion 113 has a barb portion 115 protruding from the inner surface of the small diameter hole portion 113, and the barb portion 115 is deformable when the small diameter portion 123 comes into contact with the barb portion 115 when the nib 12 is inserted. This makes it easy to insert the nib 12, and the nib 12 will not come off after insertion, and will not sink into the writing instrument 10 when writing.

[0063] Next, fifth to eighth embodiments of the present invention will be described with reference to the drawings. In the attachment structures for the soft members of the fifth to eighth embodiments, "front" refers to the soft member 22 side of the writing instrument, and "rear" refers to the opposite side. In the soft member, "front" refers to the friction portion 221 side, and "rear" refers to the opposite side.

[0064] Figure 10 is a schematic vertical cross-sectional view of the writing instrument 20 of the present invention, showing the state in which the cap 24 is attached. Figures 11 to 13 are enlarged vertical cross-sectional views of the main part showing the process of inserting the soft member 22 of the present invention, showing the process from before the soft member is inserted to after the soft member is inserted.

[0065] Fig. 14 is a cross-sectional perspective view of the barrel 21 in the fifth embodiment of the present invention, showing the state before the soft member is inserted. Figs. 15 and 16 are cross-sectional views of the barrel 21 in Fig. 11 taken along line BB, showing the cross-sectional shapes of the barb portion 215 of the barrel 21 in the fifth and sixth embodiments of the present invention.

[0066] Fig. 17 is an enlarged longitudinal cross-sectional view of a main part showing a state after a soft member has been inserted in a seventh embodiment of the present invention, which differs from the other embodiments in the shape of the outer surface of the soft member 22. Fig. 18 is an enlarged longitudinal cross-sectional view of a main part showing a state after a soft member has been inserted in an eighth embodiment of the present invention, which differs from the other embodiments in the shape of the outer surface of the soft member 22 and the part forward of the small diameter hole portion 213 of the barrel 21.

[0067] Fifth Embodiment The present invention provides a soft member mounting structure in which a soft member 22 (second part) is inserted into the rear end of a barrel 21 (first part) or the closed end of a cap (first part) of a writing instrument 20. The writing instrument 20 of this embodiment shown in FIG. 10 mainly comprises a cap 24, a nib 26, an ink occlusion body 23, a barrel 21 (first shaft 21a, second shaft 21b), and the soft member 22. The barrel 21 has the nib 26 inserted into its front end and houses the ink occlusion body 23 inside. The cap 24 may include an airtight member 25 inside to prevent ink from evaporating from the nib 26. The nib 26 is inserted into a nib insertion hole in the barrel 21 (first shaft 21a). In addition, the first shaft 21a and the second shaft 21b may be detachably engaged with each other so that the ink occlusion body 23 can be replaced or ink can be refilled into the ink occlusion body 23 with the first shaft 21a removed from the second shaft 21b.

[0068] The writing instrument 20 is a thermochromic writing instrument that contains thermochromic ink. The soft member 22 rubs the handwriting of the thermochromic ink, and the frictional heat generated at that time can thermally change the color of the handwriting of the thermochromic ink.

[0069] <Shaft tube> As shown in FIG. 10 , the barrel 21 is a bottomed cylindrical body with one open end and the other closed end, manufactured by injection molding or extrusion molding of synthetic resin. Examples of the synthetic resin material include polypropylene, polyethylene, polystyrene, polycarbonate, polyethylene terephthalate, polyacetal, acrylic, nylon, acrylonitrile-styrene copolymer resin (AS resin), and acrylonitrile-butadiene-styrene copolymer resin (ABS resin). The barrel 21 comprises a first shaft 21a and a second shaft 21b, which are axially locked and secured to each other. The first shaft 21a comprises a pen nib insertion hole, a flange, and a fitting portion. The second shaft 21b comprises a soft member insertion hole 211 and a fitted portion. The soft member insertion hole 211 of the second shaft 21b is blocked by an inner plug 27. The large diameter portion 222 of the soft member 22 is inserted into the soft member insertion hole 211. The flange portion is capable of axially abutting against the end of the opening of the second shaft 21b. The fitting portion is capable of axially locking with the fitted portion on the inner surface of the opening of the second shaft 21b to prevent it from coming off, and a first annular seal portion is formed on the outer surface of the fitting portion, which airtightly fits with a second annular seal portion on the inner circumferential surface of the fitted portion of the second shaft 21b.

[0070] 11, the soft member insertion hole 211 has, on its inner surface, a large diameter hole portion 212 on the opening side, a small diameter hole portion 213 provided behind the large diameter hole portion 212, and an inner step portion 214 having a surface perpendicular to the axis and provided between the large diameter hole portion 212 and the small diameter hole portion 213. The large diameter portion 222 of the soft member 22 is inserted or loosely inserted into the large diameter hole portion 212. The small diameter portion 223 of the soft member 22 is inserted or loosely inserted into the small diameter hole portion 213.

[0071] The small diameter hole portion 213 has a barb portion 215 that protrudes radially inward from the inner surface of the small diameter hole portion 213. As shown in FIG. 12 , the barb portion 215 is deformable when the small diameter portion 223 comes into contact with the barb portion 215 during insertion of the soft member. That is, in this embodiment, the barb portion 215 is tilted axially rearward by the outer surface of the small diameter portion 223 of the soft member 22 as the soft member 22 is inserted. This allows the small diameter portion 223 to be easily inserted. That is, there is no significant resistance when inserting the soft member 22, and the soft member 22 can be inserted smoothly.

[0072] On the other hand, if a force in the forward axial direction (i.e., a force in the direction that causes the soft member 22 to come out) is applied to the soft member 22 after the soft member 22 has been inserted (see FIG. 13), a force acts on the barb portion 215, causing it to return to the state before it was tilted. In other words, the barb portion 215 tries to restore to the state it was in before the soft member 22 was inserted (before the barb portion 215 was deformed: see FIG. 11). This allows the barb portion 215 to bite into the outer surface of the small diameter portion 223 of the soft member 22, reliably locking the soft member 22. In other words, the soft member 22 is easy to insert, and the soft member 22 will not come out after it has been inserted.

[0073] 11, in this embodiment, the barb portion 215 is provided at the rear end of the inner surface of the small diameter hole portion 213. This allows the small diameter hole portion 213 to function as a guide for inserting the small diameter portion 223, making it easier to insert the small diameter portion 223 into the small diameter hole portion 213 and allowing the soft member 22 to be inserted and attached more easily.

[0074] As shown in FIG. 14 or FIG. 15, in the present embodiment, a plurality of return portions 215 are arranged at equal intervals in the circumferential direction in the small-diameter hole portion 213, and the cross-section of the radially inner tip portion of the return portion 215 is in an R shape. However, the return portions 215 may be arranged at unequal intervals. Also, at least one return portion 215 may be formed as long as it bites into the outer surface of the small-diameter portion 223. In the present embodiment, in the state before the insertion of the soft member shown in FIG. 11, the axial thickness t of the return portion 215 is 0.1 mm, the protruding length L in the axial inward direction from the small-diameter hole portion 213 is 0.5 mm, and the circumferential width W is 0.6 mm. Preferably, 0.01 mm < t < 1.0 mm, 0.1 mm < W < 3.0 mm, and 0.1 mm < L < 2.0 mm. By setting the dimensions of the return portion 215 within these ranges, the insertion of the soft member 22 can be made easier, and the soft member 22 will not come out after insertion.

[0075] On the inner surface of the large-diameter hole portion 212 and the inner surface of the small-diameter hole portion 213, a plurality (specifically, eight) of axially extending air circulation grooves 217 are arranged at equal intervals. By means of the air circulation grooves 217, an axial air circulation path is formed between the outer surface of the soft member 22 and the inner surface of the shaft cylinder 21. Thereby, the air circulation becomes smooth, and the air in the shaft cylinder is not compressed when the soft member 22 is inserted, and the soft member 22 can be inserted smoothly.

[0076] As shown in FIG. 13, when the soft member 22 is inserted, the inner step portion 214 is abutted against the first outer step portion 224 of the soft member 22, which will be described later. Thus, since the inner step portion 214 functions as a stopper capable of positioning the soft member 22 during insertion, the soft member 22 can be easily inserted into a desired position. Also, even if the user applies excessive force to the soft member 22 during use of the soft member, the soft member 22 will not be buried in the writing instrument 20.

[0077] The writing instrument 20 of the present invention can be of a type in which an ink occlusion body 23 that holds ink is housed within the barrel 21, or of a type in which ink that is directly housed within the barrel 21 is guided to the pen tip 26 via the ink occlusion body 23. If necessary, an ink reservoir member (for example, a comb-groove-shaped ink reservoir member) that temporarily holds excess ink in response to changes in the internal pressure of the ink tank, or a guide member that guides ink from the ink occlusion body 23 that holds ink to the pen tip 26 can also be provided. Furthermore, the writing instrument may be of either a cap type or a pen tip retractable type (knock type).

[0078] <Soft materials> The soft member 22 has, on its outer surface, a large diameter portion 222, a small diameter portion 223 provided behind the large diameter portion 222, and a first outer step portion 224 provided between the large diameter portion 222 and the small diameter portion 223. The large diameter portion 222 is cylindrical and has a friction portion 221 at its tip. The small diameter portion 223 is also cylindrical. The first outer step portion 224 abuts against the inner step portion 214 of the soft member insertion hole 211 when the soft member 22 is inserted.

[0079] One end of the soft member 22 protrudes forward from the front opening of the barrel 21 as a friction portion 221. For example, as shown in FIG. 12, the friction portion 221 is machined into a bullet shape. However, the friction portion 221 is not limited to a bullet shape, and may be machined into other shapes depending on the purpose, such as a chisel shape, a rectangular shape, a square prism shape, or a plate shape. The form of the writing instrument 20 of the present invention is not limited to the illustrated example, and may be a writing instrument in which a friction body is inserted into the top (closed end side) of the cap.

[0080] The elastic synthetic resin constituting the soft member 22 is preferably made of a low-wear elastic material that generates almost no wear debris (eraser debris) during friction, rather than a high-wear elastic material (such as an eraser).

[0081] The elastic material constituting the soft member 22 is preferably, for example, an elastic synthetic resin (rubber, elastomer), such as silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin (styrene-ethylene-butylene-styrene copolymer), fluorine-based resin, chloroprene resin, nitrile resin, polyester-based resin, ethylene propylene diene rubber (EPDM), or a mixture of two or more types of rubber elastic materials, and a mixture of a rubber elastic material and a synthetic resin.

[0082] <Ink occluder> The ink occlusion body 23 may be any material that can be impregnated with ink, and specific examples thereof include a fiber bundle processed body (for example, a heat-fused fiber bundle processed body, a resin-processed fiber bundle processed body, a resin-processed felt body, or a needle-punched felt body) or a porous body (for example, an open-cell foam body made of synthetic resin such as a sponge). The outer peripheral surface of the ink occlusion body 23 may be covered with a synthetic resin film.

[0083] As shown in Figures 10 and 11, the inside plug 27 abuts against the abutment wall 216 provided on the second shaft 21b in the axial direction. The rear end face of the ink occlusion body 23 abuts against the abutment wall provided on the first shaft 21a in the axial direction. The front end face of the ink occlusion body 23 abuts against the end face of the inside plug 27 in the axial direction. It is preferable that the longitudinal dimension of the ink occlusion body 23 is set to be larger than the longitudinal dimension between the abutment wall and the inside plug 27. As a result, the ink occlusion body 23 in the barrel 21 is sandwiched in the axial direction between the abutment wall and the inside plug 27, ensuring stable writing performance.

[0084] <Pen tip> As shown in FIG. 10 , in this embodiment, the nib 26 is axially retained in the nib insertion hole of the first shaft 21a. However, the attachment structure and attachment position of the nib 26 are not limited to this embodiment. For example, the nib 26 may be attached to the outer surface of the rear end of the barrel 21 by press-fitting, engagement, screwing, fitting, adhesive bonding, two-color molding, or the like. One end of the nib 26 serves as a writing part and protrudes outward from the front opening of the barrel 21. The other end of the nib 26 is connected to the end of the ink occlusion body 23 in a piercing manner. For example, as shown in FIG. 10 , the writing part is formed into a chisel shape. However, the writing part is not limited to a chisel shape and may be formed into other shapes depending on the purpose, such as a bullet shape, a rectangular shape, a square prism shape, or a plate shape. The form of the writing instrument 20 of the present invention is not limited to the illustrated example, and may be a double-ended writing instrument in which nibs 26 of different shapes are attached to both ends of the ink occlusion body 23. In this case, the soft member 22 is inserted into the top (closed end side) of the cap 24.

[0085] The nib 26 is made of a resin-processed fiber (e.g., a resin-processed polyester fiber), one end of which protrudes externally as a writing part, and the other end is connected to one end of the ink occlusion body 23 in a piercing manner. The nib 26 may be any material as long as it allows ink to flow through it. Specific examples include a fiber nib made of a fused heat-fusible fiber, a felt nib made of felt, a plastic nib in which a plurality of resin threads (monofilaments formed by extrusion molding of synthetic resin) are fused together to form an axial ink flow passage therein, a nib made of a porous material with open cells of synthetic resin (porous tip), a calligraphy pen nib, and other nibs that utilize capillary force. The nib 26 may also be a tip formed by deforming the tip of a metal pipe inward from the outer surface, in which a ball is held in a ball-holding portion, or a tip formed by cutting a metal material with a drill or the like, in which a resin ball-receiving seat is provided inside the metal or plastic tip. The balls may be made of cemented carbide, stainless steel, ruby, ceramic, resin, rubber, etc., and have a diameter of about 0.3 to 3.0 mm, preferably 0.3 to 1.5 mm, and more preferably 0.4 to 1.0 mm.

[0086] <Ink> In this embodiment, the ink contained in the ink occlusion body 23 is a thermochromic ink. The thermochromic ink is preferably a reversible thermochromic ink. The reversible thermochromic ink may be of various types, either alone or in combination, such as a thermal decolorization type that is decolorized from a colored state by heating, a color memory retention type that alternately retains a colored state or a decolorized state within a specific temperature range, or 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.

[0087] The coloring material contained in the reversible thermochromic ink is preferably, for example, a reversible thermochromic pigment in which a reversible thermochromic composition containing at least the three essential components of (i) an electron-donating color-forming organic compound, (ii) an electron-accepting compound, and (iii) a reaction medium that determines the temperature at which the reaction (coloring reaction) in which the two compounds chemically bond with each other occurs is encapsulated in microcapsules.

[0088] The ink used in the present invention is not limited to thermochromic ink, and ink compositions other than thermochromic ink can also be used. For example, writing ink, correction fluid, liquid glue, cosmetic liquid, etc. may be selected appropriately depending on the application of the liquid ejection device. The writing ink is not particularly limited to oil-based ink or water-based ink.

[0089] Sixth Embodiment 11, showing the shape of the barb portion 215 of the barrel 21 in the sixth embodiment of the present invention. In the sixth embodiment of the present invention, the cross-sectional shape of the barb portion 215 is different from that in the fifth embodiment. Specifically, the cross-section of the radially inner tip portion is sharp-pointed.

[0090] The other configurations of the sixth embodiment are substantially the same as those of the fifth embodiment, and therefore detailed description thereof will be omitted. As shown in Fig. 16, according to this embodiment, the barbs 215 dig into the outer surface of the soft member 22 at equal intervals around the circumference, thereby more reliably locking the soft member 22. Furthermore, because the cross section of the radially inner tip of the barb 215 is sharp-pointed, the barb 215 digs deeper into the outer surface of the soft member 22, and the soft member 22 is more firmly locked in the axial direction and prevented from slipping out.

[0091] However, the cross section of the tip of barb portion 215 is not limited to a sharp shape or the aforementioned R shape, and may be other shapes according to the pen tip, such as a rectangular shape, an inverted R shape with a radially inward tip recessed, etc. Also, barb portion 215 may be a burr formed when resin gets into the gap between the mating surfaces of the mold (pin) when barrel 21 is manufactured by injection molding.

[0092] Seventh Embodiment Fig. 17 is an enlarged longitudinal cross-sectional view of a main part of the seventh embodiment of the present invention, showing the state after the soft member 22 has been inserted. In the seventh embodiment of the present invention, the shape of the soft member 22 rearward of the first outer step 224 is different from that of the fifth embodiment. Specifically, as shown in Fig. 17, the soft member 22 has a locking groove 225 rearward of the first outer step 224 and a second outer step 226 at the rear end of the locking groove 225, and the barb portion 215 is locked in the second outer step 226, thereby preventing the soft member 22 from coming off in the axial direction. The locking groove 225 is preferably formed circumferentially on the small diameter portion 223.

[0093] The other configurations of the seventh embodiment are substantially the same as those of the fifth embodiment, and therefore detailed description thereof will be omitted. According to this embodiment, as in the fifth embodiment, when an axial forward force (i.e., a force in the direction in which the soft member 22 is removed) is applied to the soft member 22 after the soft member 22 is inserted, a force acts on the barb portion 215 to return it to its pre-tilt state. At this time, as shown in FIG. 17 , the barb portion 215 catches on the second outer step portion 226 provided on the outer surface of the small diameter portion 223, which can more reliably prevent the soft member 22 from being removed after the soft member 22 is inserted. Furthermore, because the locking groove 225 is formed circumferentially on the small diameter portion 223, positioning of the soft member 22 in the rotational direction is not required when inserting the soft member 22 into the barrel 21, and the soft member 22 can be easily inserted.

[0094] Eighth Embodiment 18 is an enlarged longitudinal cross-sectional view of a main part of the eighth embodiment of the present invention, showing the state after the soft member 22 has been inserted. In the eighth embodiment of the present invention, the shape of the barrel 21 forward of the small diameter hole portion 213 is different from that of the seventh embodiment. Specifically, as shown in FIG. 18, the large diameter hole portion 212 of the barrel 21 is omitted, and an inner step portion 214 is provided at the front end of the barrel 21.

[0095] In the eighth embodiment of the present invention, the outer surface shape of the soft member 22 is different from that of the seventh embodiment. Specifically, as shown in Fig. 18, the soft member 22 has a locking groove 225 on the surface of the small diameter portion rearward of the first outer step 224, and a second outer step 226 at the rear end of the locking groove 225, and the friction portion 221 has a bullet shape. In addition, when the first outer step 224 and the inner step 214 of the soft member 22 abut against each other, an air circulation hole 227 is formed between the first outer step 224 and the inner step 214. This allows smooth air circulation, and the air inside the barrel is not compressed when the soft member 22 is inserted, allowing the soft member 22 to be inserted smoothly.

[0096] Other configurations of the eighth embodiment are substantially the same as those of the seventh embodiment, and therefore detailed description thereof will be omitted. According to this embodiment, the soft member 22 can be clamped further forward, closer to the friction portion 221, and therefore stable friction can be achieved.

[0097] The soft member mounting structure configured as above operates as follows.

[0098] The soft member mounting structure of the present invention is a soft member mounting structure formed by inserting a soft member 22 into the tail end of a barrel 21 of a writing instrument 20 or the closed end of a cap 24, and the soft member 22 has a soft member insertion hole 211 provided in the tail end of the barrel 21 or the closed end of the cap 24, and the soft member 22 has a small diameter portion 223, a large diameter portion 222 provided in front of the small diameter portion 223, and a first outer step portion 224 provided between the small diameter portion 223 and the large diameter portion 222. The soft member insertion hole 211 has a small diameter hole portion 213 and an inner step portion 214 provided in front of the small diameter hole portion 213, the small diameter portion 223 is inserted or loosely inserted into the small diameter hole portion 213, the first outer step portion 224 and the inner step portion 214 abut against each other, the small diameter hole portion 213 has a barb portion 215 protruding from the inner surface of the small diameter hole portion 213, and the barb portion 215 can be deformed by contact with the small diameter portion 223 when the soft member is inserted.

[0099] According to the present invention, the barb portion 215 can be deformed by contact with the small diameter portion 223 of the soft member 22 when the soft member 22 is inserted, and therefore does not provide significant resistance when the soft member 22 is inserted, allowing the soft member 22 to be inserted smoothly. On the other hand, if a force in the forward axial direction (i.e., a force in the direction in which the soft member 22 is removed) is applied to the soft member 22 after the soft member is inserted, the barb portion 215 attempts to restore to the state it was in before the soft member was inserted (before deformation), and the barb portion 215 bites into the outer surface of the small diameter portion 223 of the soft member 22, reliably locking the soft member 22. In other words, the soft member 22 is easily inserted, and the soft member 22 will not come off after insertion.

[0100] Furthermore, according to the present invention, the inner step 214 functions as a stopper that can determine the position when the soft member is inserted, so that the soft member 22 can be easily inserted and attached at the desired position. Furthermore, even if the user applies excessive force to the soft member 22 while using the soft member, the soft member 22 will not sink into the writing instrument 20.

[0101] Preferably, the barb portion 215 is provided at the rear end of the inner surface of the small diameter hole portion 213. This allows the small diameter hole portion 213 to function as a guide for inserting the small diameter portion 223, making it easier to insert the small diameter portion 223 into the small diameter hole portion 213 and making it easier to insert and attach the soft member 22.

[0102] Preferably, the soft member insertion hole 211 further includes a large diameter hole portion 212 provided in front of the inner step portion 214, and the large diameter portion 222 is inserted or loosely fitted into the large diameter hole portion 212. This allows the soft member 22 to be clamped further forward, thereby achieving stable friction.

[0103] Preferably, a plurality of barbs 215 are arranged at equal intervals around the circumference of small diameter hole 213, and the cross section of the tip of each barb 215 is rounded. This allows barbs 215 to bite into the outer surface of soft member 22 at equal intervals around the circumference, more reliably locking soft member 22. Furthermore, because the cross section of the tip of each barb 215 is rounded, barbs 215 can be easily formed.

[0104] Preferably, the soft member 22 has a locking groove 225 behind the first outer step 224 and a second outer step 226 at the rear end of the locking groove 225, and the barb portion 215 is locked in the second outer step 226, preventing the soft member 22 from slipping out in the axial direction. As a result, if a force in the axial forward direction (i.e., a force in the direction that causes the soft member 22 to slip out) is applied to the soft member 22 after the soft member is inserted, a force acts on the barb portion 215 to return it to its state before tilting. At this time, the barb portion 215 gets caught on the second outer step 226 provided on the outer surface of the small diameter portion 223, making it possible to more reliably prevent the soft member 22 from slipping out after the soft member is inserted.

[0105] The present invention also covers only the barrel 21 of the writing implement 20. That is, the barrel 21 of the writing implement 20 has a soft member insertion hole 211 with a soft member 22 inserted into its front end, and the outer surface of the soft member 22 has a large diameter portion 222, a small diameter portion 223 provided behind the large diameter portion 222, and a first outer step portion 224 provided between the large diameter portion 222 and the small diameter portion 223, and the inner surface of the soft member insertion hole 211 has a large diameter hole portion 212, a small diameter hole portion 213 provided behind the large diameter hole portion 212, and a first outer step portion 224 provided between the large diameter portion 222 and the small diameter portion 223. The barrel 21 of the writing instrument 20 has an inner step 214 provided between the large diameter hole 212 and the small diameter hole 213, the small diameter portion 223 is inserted or loosely inserted into the small diameter hole 213, the first outer step 224 and the inner step 214 are abutted against each other, the small diameter hole 213 has a barb 215 protruding from the inner surface of the small diameter hole 213, and the barb 215 is deformable when the small diameter portion 223 comes into contact with the barb 215 when a soft member is inserted. This makes it easy to insert the soft member 22, but the soft member 22 will not come off after insertion, and the soft member 22 will not sink into the writing instrument 20 during friction.

[0106] The present invention also relates to a writing implement that includes the soft member mounting structure and that forms thermochromic handwriting.The present invention also relates to a soft member that, together with the soft member insertion hole 211, constitutes the soft member mounting structure.

[0107] <Ninth to Eleventh Embodiments> Ninth to eleventh embodiments of the present invention will be described below with reference to the drawings. In the mounting structures of the ninth to eleventh embodiments, "front" refers to the end 321 side of the second component 32, and "rear" refers to the opposite side.

[0108] Figure 19 is a schematic vertical cross-sectional view of a portion of a writing instrument 30 according to a ninth embodiment of the present invention. Figure 20 is a schematic vertical cross-sectional view of a portion of a writing instrument 30 according to a tenth embodiment of the present invention. Figure 21 is a schematic vertical cross-sectional view of a portion of a writing instrument 30 according to an eleventh embodiment of the present invention. In Figure 19, the top of the figure is the front and the bottom of the figure is the back. In Figures 20 and 21, the top of the figure is the back and the bottom of the figure is the front.

[0109] In all of the ninth to eleventh embodiments of the present invention, the attachment structure is formed by attaching the second part 32 to an insertion hole 311 provided at the end of the first part 31. The writing implement 30 of the ninth to eleventh embodiments mainly comprises a cap, a nib, an ink occlusion body, a barrel, and a soft member, as in the first to eighth embodiments, for example.

[0110] The writing instrument 30 comprises a first part 31 and a second part 32. In the ninth embodiment shown in FIG. 19, the first part 31 is the barrel or cap of the writing instrument 30, and the second part 32 is the tail plug of the barrel or the crown of the cap. In the tenth embodiment shown in FIG. 20, the first part 31 is the cap, and the second part 32 is a rubber seal. In the eleventh embodiment shown in FIG. 21, the first part 31 is the cap, and the second part 32 is an inner cap.

[0111] The first part 31 is a cylinder with one open end that is manufactured by injection molding or extrusion molding of synthetic resin. An insertion hole 311 is formed in the first part 31. The large-diameter portion 322 of the second part 32 is inserted into the insertion hole 311. Examples of the synthetic resin material include polypropylene, polyethylene, polystyrene, polycarbonate, polyethylene terephthalate, polyacetal, acrylic, nylon, acrylonitrile-styrene copolymer resin (AS resin), acrylonitrile-butadiene-styrene copolymer resin (ABS resin), and other synthetic resins.

[0112] The insertion hole 311 has on its inner surface a small diameter hole portion 313 and an inner step portion 314 that is connected to the small diameter hole portion 313 and has a surface perpendicular to the axis. The small diameter portion 323 of the second component 32 is inserted or loosely inserted into the small diameter hole portion 313. The insertion hole 311 may further have on its inner surface a large diameter hole portion. In this case, the large diameter portion 322 of the second component 32 is inserted or loosely inserted into the large diameter hole portion.

[0113] The small diameter hole portion 313 has a barb portion 315 that protrudes radially inward from the inner surface of the small diameter hole portion 313. The barb portion 315 is deformable when the small diameter portion 323 comes into contact with the barb portion 315 during insertion of the second component 32. That is, in this embodiment, the barb portion 315 is tilted axially rearward by the outer surface of the small diameter portion 323 of the second component 32 as the second component 32 is inserted. This allows the small diameter portion 323 to be easily inserted. That is, there is no significant resistance when inserting the second component 32, and the second component 32 can be inserted smoothly.

[0114] On the other hand, if a force in the axial direction (i.e., a force in the direction that causes the second component 32 to come out) is applied to the second component 32 after the second component 32 is inserted, a force acts on the barb portion 315, causing it to return to its pre-tilt state. In other words, the barb portion 315 attempts to restore its state before the second component 32 was inserted (before the barb portion 315 was deformed). This allows the barb portion 315 to hook onto a second outer step 326 provided on the outer surface of the small diameter portion 323 of the second component 32, as described below, and more reliably prevents the second component 32 from coming out after the second component 32 is inserted. In other words, the second component 32 is easy to insert, but the second component 32 does not come out after insertion. The barb portion 315 may bite into the outer surface of the small diameter portion 323 of the second component 32 to lock the second component 32.

[0115] In this embodiment, barb portion 315 is provided at the rear end of the inner surface of small diameter hole portion 313. This allows small diameter hole portion 313 to function as a guide for inserting small diameter portion 323, making it easier to insert small diameter portion 323 into small diameter hole portion 313 and making it easier to insert second component 32.

[0116] In this embodiment, a plurality of barbs 315 are disposed at equal intervals around the circumference of the small diameter hole portion 313, and the radially inner tip of each barb 315 has an R-shaped cross section. However, the barbs 315 may be disposed at unequal intervals. Furthermore, it is sufficient that at least one barb 315 is formed and digs into the outer surface of the small diameter portion 323. The dimensions of the barb 315 may be set similarly to the barbs 115 and 215 of the first to eighth embodiments.

[0117] A plurality of (specifically, eight) air flow grooves 317 extending in the axial direction are arranged at equal intervals on the inner surface of small diameter hole portion 313. Air flow grooves 317 form an axial air flow passage between the outer surface of second component 32 and the inner surface of first component 31. This allows smooth air flow, and the air inside the barrel is not compressed when second component 32 is inserted and attached, allowing second component 32 to be inserted and attached smoothly.

[0118] When the second part 32 is inserted, a first outer step 324 of the second part 32, which will be described later, comes into contact with the inner step 314. This allows the inner step 314 to function as a stopper that can determine the position of the second part 32 when it is inserted, making it easy to insert the second part 32 in the desired position. Furthermore, even if the user applies excessive force to the second part 32, the second part 32 will not sink into the writing instrument 30.

[0119] The second part 32 has, on its outer surface, a large diameter portion 322, a small diameter portion 323 provided behind the large diameter portion 322, and a first outer step 324 provided between the large diameter portion 322 and the small diameter portion 323. The large diameter portion 322 is columnar or cylindrical. The small diameter portion 323 is cylindrical. The first outer step 324 abuts against the inner step 314 of the insertion hole 311 when the second part 32 is inserted. The second part 32 is made of synthetic resin. The type of synthetic resin can be determined appropriately depending on the application of the second part 32.

[0120] The second part 32 has a locking groove 325 behind the first outer step 324 and a second outer step 326 at the rear end of the locking groove 325, and the barb portion 315 is locked in the second outer step 326, thereby preventing the second part 32 from coming off in the axial direction. The locking groove 325 is preferably formed circumferentially on the small diameter part 323.

[0121] The second part 32 (tail cap or crown) of the ninth embodiment closes the end of the first part 31. The second part 32 (rubber seal) of the tenth embodiment seals the ballpoint pen tip 33. The second part 32 (inner cap) of the eleventh embodiment prevents ink from evaporating from the highlighter pen tip 33.

[0122] As in the first to eleventh embodiments, the first part of the present invention may be any of various parts of a writing instrument, such as a writing instrument body, a barrel, and a cap. The second part of the present invention may be any of various parts of a writing instrument, such as a nib, a soft member, a tail cap, a crown cap, a rubber seal, and an inner cap. The terms "front" and "rear" in the present invention may vary depending on the first and second parts. [Explanation of symbols]

[0123] 10,20,30 Writing instruments 11,21 Shaft cylinder 31 First Part 11a Front axle 11b rear axle 21a 1st axis 21b 2nd axis 111 Pen tip insertion hole 211 Soft member insertion hole 311 Insertion hole 112,212 Large diameter hole 113,213,313 Small diameter hole 114,214,314 Inner section 115,215,315 Barb 116,216 Contact wall 117,217,317 Air circulation groove 12 Pen Tips 22 Soft materials 32 Second Part 121 Writing Department 221 Friction part 321 End 122,222,322 Large diameter section 123,223,323 Small diameter part 124,224,324 First outer section 125,225,325 Locking groove 126,226,326 Second outer section 127,227 Air vent 13,23 Ink occlusion body 33 Pen tip 14,24 Cap 15,25 Airtight member 16 Soft materials 26 Pen Tip 27 Inner stopper

Claims

1. a first component; a second component inserted into an insertion hole provided at an end of the first component; A mounting structure for a writing instrument comprising: the second component includes a small diameter portion, a large diameter portion provided in front of the small diameter portion, and a first outer step portion provided between the small diameter portion and the large diameter portion, the insertion hole includes a small diameter hole portion and an inner step portion provided in front of the small diameter hole portion, The small diameter portion is inserted or loosely inserted into the small diameter hole portion, the first outer step portion and the inner step portion are in contact with each other, The small diameter hole portion has a barb portion protruding from an inner surface of the small diameter hole portion, and the barb portion is deformable by contact with the small diameter portion when the second component is inserted. Mounting structure.

2. The barb portion is provided at the rear end of the inner surface of the small diameter hole portion. The mounting structure according to claim 1 .

3. the insertion hole further includes a large diameter hole portion provided in front of the inner step portion, The large diameter portion is inserted or loosely fitted into the large diameter hole portion. The mounting structure according to claim 1 .

4. The mounting structure according to claim 1 , wherein a plurality of said barbs are disposed at equal intervals around the circumference of said small diameter hole.

5. 2. The mounting structure according to claim 1, wherein the tip of the barb has a cross section that is rounded.

6. The second component has a locking groove behind the first outer step and a second outer step at the rear end of the locking groove, and the barb is locked with the second outer step, preventing the second component from coming off in the axial direction. The mounting structure according to claim 1 .

7. the first part is a writing instrument body, the second part is a pen tip; The insertion hole is provided in the front part of the writing implement body.

7. The mounting structure according to claim 1.

8. the first part is a barrel or a cap of the writing instrument, the second part is a soft member, The insertion hole is provided at the tail end of the barrel or the closed end of the cap.

7. The mounting structure according to claim 1.

9. A writing implement comprising the attachment structure according to claim 8, and capable of producing thermochromic writing marks.

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