Writing implement with erasing member

Abstract

To provide a writing implement equipped with an erasing member that can be easily attached. [Solution] A writing instrument 1 has an erasing member 2 attached to the rear end of the writing instrument body 3 or the front end of the cap 4, and the end has an engaging portion 14 arranged on the central axis and a connecting portion 15 connecting the end and the engaging portion 14, and the erasing member 2 has an engaging hole 2c that receives the engaging portion 14 and the connecting portion 15, and when the erasing member 2 is attached, a gap space 17 is formed around the connecting portion 15.

Description

[Technical field]

[0001] The present invention relates to a writing instrument equipped with an erasing member. [Background technology]

[0002] There is known a writing instrument that has a separate erasing member at the top of a cap, and that allows handwriting drawn on paper or the like with the writing instrument to be erased by the erasing member (for example, Patent Document 1).

[0003] Patent Document 2 also describes an attachment structure for attaching a soft member corresponding to an erasing member to the upper end of a cylindrical body such as a shaft tube or a cap of a writing instrument. According to the attachment structure described in Patent Document 2, a protrusion is provided at the upper end of the cylindrical body, an attachment hole is provided at the lower end of the erasing member, and the attachment is performed by inserting and fitting the protrusion into the attachment hole. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-200694 A [Patent Document 2] JP 2009-214515 A Summary of the Invention [Problem to be solved by the invention]

[0005] The writing implement described in Patent Document 1 is designed to be replaced when the erasing member is worn out, and so the cap and the erasing member are not firmly attached. Therefore, when the erasing member is used to rub handwriting, rattling occurs between the cap and the erasing member, which can make it difficult to erase stably.

[0006] In contrast, according to the mounting structure described in Patent Document 2, although the erasing member can be firmly mounted, the contact area between the outer peripheral surface of the protrusion of the cylinder and the inner peripheral surface of the mounting hole of the erasing member increases as the protrusion is inserted into the mounting hole. In other words, the force against the frictional resistance required to insert the protrusion into the mounting hole, i.e., the press-fit force, also increases accordingly, making it difficult to firmly insert the protrusion all the way into the mounting hole.

[0007] It is an object of the present invention to provide a writing instrument with an erasing member that can be easily attached, and it is also an object of the present invention to provide a writing instrument with an erasing member that is firmly attached. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a writing instrument comprising a cap equipped with an erasing member and a barrel into which the cap fits, a clip portion being integrally formed on a side of the cap via a connection portion, and the clip portion being a substantially rectangular plate-like member extending in the axial direction.

[0009] In this specification, the writing tip side in the axial direction of the writing instrument is defined as the "front" side, and the opposite side to the writing tip side is defined as the "rear" side. Also, in the axial direction of the cap, the open end side into which the writing instrument body is inserted is defined as the "rear" side, and the opposite side is defined as the "front" side.

[0010] According to another embodiment, the connection portion has a T-shaped cross section.

[0011] According to another aspect, a guide surface is formed on the front end surface of the clip portion so that the angle A between the paper surface and the central axis of the writing implement during an erasing operation is in the range of 40 to 80 degrees.

[0012] According to another aspect, the cap is formed of a material harder than the portion of the barrel with which the cap fits.

[0013] According to another aspect, the width of the clip portion and the diameter of the cap are substantially the same, and the clip portion extends to the center of gravity of the writing instrument. Effect of the Invention

[0014] Each of the aspects has a common effect of providing a writing instrument with an erasing member that can be easily attached. Furthermore, each of the aspects has an effect of providing a writing instrument with an erasing member that is firmly attached. [Brief description of the drawings]

[0015] [Figure 1] 1 is a longitudinal sectional view of a writing instrument according to a first embodiment, which is provided with an erasing member according to one aspect of the present invention. [Diagram 2] FIG. 2 is a perspective view of the cap of the writing instrument shown in FIG. [Diagram 3] FIG. 3 is a vertical cross-sectional view of the cap shown in FIG. 2. [Figure 4] 3 is another vertical cross-sectional view of the cap shown in FIG. 2. [Diagram 5] 2 is a perspective view of an erasing member of the writing instrument shown in FIG. 1. [Figure 6] 2 is another perspective view of the erasing member of the writing instrument shown in FIG. 1. [Figure 7] FIG. 6 is a vertical cross-sectional view of the erasing member shown in FIG. 5. [Figure 8] 2 is a perspective view of a cap to which an erasing member of the writing instrument shown in FIG. 1 is attached. FIG. [Figure 9] FIG. 9 is a side view of the cap shown in FIG. 8. [Figure 10] 9 is a longitudinal sectional view of the cap shown in FIG. 8 taken along line XX in FIG. [Figure 11] 9 is another vertical cross-sectional view of the cap shown in FIG. 8. [Figure 12] 9A is a cross-sectional view of the cap shown in FIG. 8 taken along line YY in FIG. [Figure 13] 9 is a cross-sectional view of the cap shown in FIG. 8 taken along line ZZ in FIG. [Figure 14]2 is an enlarged cross-sectional view showing an attachment portion of the erasing member and the cap of the writing implement shown in FIG. 1. FIG. [Figure 15] 2 is a perspective view of a cap of an alternative embodiment to the cap of the writing instrument shown in FIG. 1. FIG. [Figure 16] FIG. 16 is a longitudinal sectional view of the cap shown in FIG. [Figure 17] 2 is a perspective view of a cap to which an erasing member of a different embodiment from the erasing member of the writing instrument shown in FIG. 1 is attached. FIG. [Figure 18] FIG. 18 is a longitudinal sectional view of the cap shown in FIG. [Figure 19] FIG. 18 is a vertical cross-sectional view of the erasing member shown in FIG. [Figure 20] 2 is a perspective view of a cap to which an erasing member of a further embodiment different from the erasing member of the writing implement shown in FIG. 1 is attached. FIG. [Figure 21] FIG. 21 is a perspective view of the erasing member shown in FIG. 20. [Figure 22] FIG. 21 is a front view of the erasing member shown in FIG. 20. [Figure 23] 2 is a perspective view of a cap to which an erasing member of a further embodiment different from the erasing member of the writing implement shown in FIG. 1 is attached. FIG. [Figure 24] FIG. 24 is a perspective view of the erasing member shown in FIG. 23. [Diagram 25] FIG. 24 is a front view of the erasing member shown in FIG. 23. [Figure 26] 2 is a perspective view of a cap to which an erasing member of a further embodiment different from the erasing member of the writing implement shown in FIG. 1 is attached. FIG. [Figure 27] FIG. 27 is a perspective view of the erasing member shown in FIG. 26. [Figure 28] FIG. 27 is a front view of the erasing member shown in FIG. 26. [Figure 29] 2 is a perspective view of a cap to which an erasing member of a further embodiment different from the erasing member of the writing implement shown in FIG. 1 is attached. FIG. [Diagram 30] FIG. 30 is a perspective view of the erasing member shown in FIG. 29. [Diagram 31] FIG. 30 is a front view of the erasing member shown in FIG. 29. [Diagram 32] FIG. 4 is a longitudinal sectional view of a writing instrument according to a second embodiment, which is provided with an erasing member according to one aspect of the present invention. [Diagram 33] FIG. 33 is a perspective view of the cap of the writing instrument shown in FIG. 32. [Diagram 34] FIG. 34 is a plan view of the cap shown in FIG. 33. [Diagram 35] FIG. 34 is a side view of the cap shown in FIG. 33. [Diagram 36] FIG. 34 is a longitudinal sectional view of the cap shown in FIG. 33. [Figure 37] 35. A cross-sectional view of the cap shown in FIG. 33 taken along line SS in FIG. [Figure 38] 33 is a diagram showing a state in which the cap to which the erasing member of the writing implement shown in FIG. 32 is attached is used for erasing. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Corresponding components are designated by common reference numerals throughout the drawings.

[0017] FIG. 1 is a vertical cross-sectional view of a writing instrument 1 according to a first embodiment having an erasing member 2 according to one aspect of the present invention. The writing instrument 1 is a ballpoint pen type writing instrument, and has a writing instrument body 3 having a refill 5 and a cylindrically extending barrel 6, and a cap 4. The barrel 6 has a cylindrical front barrel 7 and a rear barrel 8 whose front end is screwed into the rear end of the front barrel 7. The front barrel 7 and the rear barrel 8 are formed of a resin material. For example, in this embodiment, the front barrel 7 is formed of a polypropylene resin, and the rear barrel 8 is formed of a polycarbonate resin. By forming the front barrel 7 from a material softer than the material of the cap 4 described later, it is possible to prevent cracking during fitting. A hole is formed at the front end of the front barrel 7 to allow the writing tip 11 of the refill 5 to protrude. In this specification, in the axial direction of the writing instrument 1, the writing tip side is defined as the "front" side, and the opposite side to the writing tip is defined as the "rear" side. In addition, in the axial direction of the cap 4, the open end side into which the writing implement body is inserted is defined as the "rear" side, and the opposite side is defined as the "front" side.

[0018] The refill 5 has a cylindrical refill body 9, a joint member 10, a writing tip portion 11, and a refill plug 12. The refill body 9 is formed of a resin material such as polypropylene or a metal material, and is configured to contain ink. The joint member 10 is formed of a resin material such as polypropylene, polybutylene terephthalate, polyacetal, or a metal material. The rear end of the writing tip portion 11 is attached to the front end of the joint member 10. The refill 5 is housed in the barrel 6, and a part of the writing tip portion 11 is exposed through the hole of the tip barrel 7 described above when housed in the barrel 6. The writing tip portion 11, which is the writing portion, holds a ball at its tip, and ink housed in the refill body 9 is discharged through the joint member 10 according to the rotation of the ball during writing. The refill plug 12 is press-fitted into the rear end of the refill body 9, and is attached by fitting due to this press-fitting.

[0019] The cap 4 has a cap body 4a, a clip portion 4b, a seal member 13, and an erasing member 2. The cap body 4a is a cylindrical member, and the clip portion 4b is integrally provided on its side. The clip portion 4b is configured to have elasticity so that articles such as documents and clothes can be clamped between the cap body 4a and the clip portion 4b. Therefore, examples of materials for forming the cap body 4a and the clip portion 4b include synthetic resins such as polycarbonate and acrylonitrile butadiene styrene. As mentioned above, it is preferable that they are formed of a material harder than the front barrel 7.

[0020] Furthermore, the seal member 13 protects the writing tip 11 by engaging with the writing tip 11 when the cap 4 is attached to the tip barrel 7 and elastically deforming. Examples of materials for forming the seal member 13 include synthetic rubbers such as isopropylene rubber, butadiene rubber, nitrile rubber, silicone rubber, butyl rubber, ethylene propylene diene rubber, styrene butadiene rubber, and fluororubber. Butyl rubber (IIR) in particular can further improve the processability and volatilization prevention performance of the tip of the writing part. That is, butyl rubber is not only excellent in processability, but also has excellent airtightness (gas barrier properties) among various rubbers. For this reason, by forming the seal member from butyl rubber, it is possible to more reliably prevent the writing tip from drying and the solvent components in the ink from volatilizing.

[0021] Next, the structure of the cap 4 will be described with reference to Figures 2 to 4. Figure 2 is a perspective view of the cap 4 of the writing instrument shown in Figure 1, Figure 3 is a vertical cross-sectional view of the cap 4 shown in Figure 2, and Figure 4 is another vertical cross-sectional view of the cap 4 shown in Figure 2. Figure 4 is a cross-sectional view at a position rotated 90 degrees around the central axis with respect to the cross-sectional view shown in Figure 3.

[0022] An engagement portion 4c that engages with the tip barrel 7 is provided on the inner wall of the cap body 4a near the open end. Three or more ribs 4e that extend in the axial direction of the writing instrument 1 are provided at equal intervals in the circumferential direction on the inside of the front end 4d of the cap body 4a, i.e., near the top. In this embodiment, the cap body 4a has six ribs 4e. As shown in FIG. 1, the seal member 13 is sandwiched between the ribs 4e.

[0023] The ribs 4e each have the same axial length, but only two ribs (long ribs) 4f arranged opposite to the central axis may extend longer toward the rear of the cap 4 than the other ribs 4e. These long ribs 4f serve as guides when inserting the seal member 13 during assembly of the cap 4, making the insertion easier. In addition, when the cap 4 is made of a transparent or translucent material, one of the long ribs 4f may be arranged at a position corresponding to directly below the clip portion 4b extending in the longitudinal direction. This allows the clip portion 4b and the opposing long rib 4f to be arranged on approximately the same plane passing through the central axis of the cap 4, creating an aesthetic impression.

[0024] The front end 4d of the cap body 4a is provided with a fitting portion 14 arranged on the central axis, two connection portions 15 connecting the end 4d and the fitting portion 14, and a support wall 16 arranged around the fitting portion 14 and the connection portions 15. In addition, the front end 4d of the cap body 4a is provided with a circular ventilation opening 4g around the central axis, but the ventilation opening 4g may be omitted.

[0025] The fitting portion 14 has a truncated cone shape with a larger diameter at the rear end and a smaller diameter toward the front end. The front end surface edge 14a of the fitting portion 14 is rounded and chamfered. The rear end surface edge 14b has a corner 14c of 90 degrees or an acute angle. The shape of the fitting portion 14 is not limited to a truncated cone shape, and may be a sphere, a cylinder, a polygonal truncated pyramid, or the like.

[0026] The connection parts 15 are two columnar members extending from the inner wall of the ventilation opening 4g toward the front of the cap 4, and are arranged symmetrically with respect to the central axis of the cap 4. The fitting part 14 is supported by the connection parts 15 so that its disk-shaped surface is perpendicular to the central axis of the cap 4. The fitting part 14 is also supported by the connection parts 15 at its rear end surface near its edge. As is clear from FIG. 3, the connection parts 15 do not extend along the central axis, but extend at a slight incline toward the central axis as they move forward. The cap body 4a has a ventilation opening and the two connection parts 15 are spaced apart, so that air can flow from the front end to the rear end of the cap body 4a.

[0027] In this embodiment, the cap body 4a, the fitting portion 14, and the connection portion 15 are integrally formed, but may be formed separately. Also, in this embodiment, there are two connection portions 15, but there may be one or three or more connection portions. When there is one connection portion 15, it is connected to the vicinity of the center of the opposing surface of the fitting portion 14. Also, when the ventilation opening 4g is not provided at the front end portion 4d of the cap body 4a, it is configured to extend forward from the front end portion 4d of the cap body 4a.

[0028] The support wall 16 is a tubular member disposed around the fitting portion 14 and the connection portion 15. The outer peripheral surface of the support wall 16 is formed flush with the outer peripheral surface of the cap body 4a. In this embodiment, the cap body 4a and the support wall 16 are integrally formed, but may be formed separately. The support wall 16 has an inner peripheral surface 16a into which the insertion portion 2a of the erasing member 2 fits, as described below.

[0029] Next, the structure of the erasing member 2 will be described with reference to Figures 5 to 7. Figure 5 is a perspective view of the erasing member 2 of the writing instrument 1 shown in Figure 1, Figure 6 is another perspective view of the erasing member 2 of the writing instrument 1 shown in Figure 1, and Figure 7 is a vertical cross-sectional view of the erasing member 2 shown in Figure 5.

[0030] The erasing member 2 has an insertion portion 2a that is inserted between the support walls 16 of the cap body 4a and surrounded by the insertion portion 2a, an erasing portion 2b that is exposed to the outside when the erasing member 2 is attached to the cap and is used to scratch paper surfaces, and a fitting hole 2c that extends in the axial direction and penetrates the insertion portion 2a and the erasing portion 2b. The insertion portion 2a and the erasing portion 2b may be formed integrally. Examples of materials that can be used to form the erasing member 2 include rubber materials such as silicone rubber, nitrile rubber, ethylene propylene rubber, and ethylene propylene diene rubber, thermoplastic elastomers such as styrene-based elastomers, olefin-based elastomers, and polyester-based elastomers, rubber elastic materials, mixtures of two or more types of elastic materials, mixtures of rubber elastic materials and synthetic resins, commercially available erasers, and the like.

[0031] The insertion part 2a is substantially cylindrical in shape corresponding to the shape of the inner peripheral surface 16a of the support wall 16 of the cap body 4a, and has an annular engagement protrusion 2d on its side in the circumferential direction. The engagement protrusion 2d abuts against the inner peripheral surface 16a of the support wall 16 to hold the erasing member 2 in place of the annular engagement protrusion 2d so that the erasing member 2 does not rattle when attached to the cap 4. Note that instead of the annular engagement protrusion 2d, multiple protrusions may be formed in the circumferential direction. Also, if rattling of the erasing member 2 can be prevented by other means, the engagement protrusion 2d may not be provided.

[0032] A flat portion 2e may be provided along the axial direction on a part of the side surface of the insertion portion 2a. When the eraser 2 is formed by injection molding, the flat portion 2e can be used as the gate position during molding. Even if a gate residue occurs on the flat portion 2e after molding, the gate residue can be prevented from contacting the inner surface because there is a clearance between the surface of the flat portion 2e and the inner surface 16a of the support wall 16 of the cap body 4a. In addition, as described later, by providing a protrusion corresponding to the inner surface 16a of the support wall 16, it is possible to position the eraser 2 in a predetermined direction during installation, and the eraser 2 can be prevented from rotating after installation.

[0033] The erasing portion 2b has a truncated cone shape with a larger diameter at the rear end and a smaller diameter toward the front end. The edge of the front end surface of the erasing portion 2b is rounded and chamfered. The rear end portion of the erasing portion 2b has a larger diameter than the insertion portion 2a, and therefore forms a stepped jaw portion 2f between the insertion portion 2a and the rear end surface of the jaw portion 2f. When the erasing member 2 is attached to the cap, the rear end surface of the jaw portion 2f abuts against the front end surface 16b of the support wall 16.

[0034] The fitting hole 2c extends in the axial direction and penetrates the insertion portion 2a and the erasing portion 2b. The fitting hole 2c receives the fitting portion 14 and the connection portion 15 of the cap 4 when the erasing member 2 is attached to the cap 4. The fitting hole 2c is divided into a tapered portion 2g, a small diameter portion 2h, and a large diameter portion 2i, in that order from the rear end portion into which the fitting portion 14 is inserted, i.e., the entrance portion. The tapered portion 2g is tapered from the rear end portion of the fitting hole 2c toward the front, i.e., from the entrance portion toward the back. The inner diameter of the front end of the tapered portion 2g and the inner diameter of the rear end of the small diameter portion 2h are set to be approximately equal. The boundary between the small diameter portion 2h and the large diameter portion 2i is stepped, forming a locking portion 2j that prevents the fitting portion 14 from coming off, as described later. The small diameter portion 2h may be omitted.

[0035] In this embodiment, since the fitting hole 2c is a through hole, even if the erasing member 2 comes off the cap after product shipment and is accidentally swallowed by a small child or the like, safety can be ensured without blocking the airway.

[0036] Next, the attachment of the erasing member 2 and the cap 4 will be described with reference to Figs. 8 to 14. Fig. 8 is a perspective view of the cap 4 to which the erasing member 2 of the writing instrument 1 shown in Fig. 1 is attached, Fig. 9 is a side view of the cap 4 shown in Fig. 8, Fig. 10 is a vertical cross-sectional view of the cap 4 shown in Fig. 8 taken along line XX in Fig. 9, Fig. 11 is another vertical cross-sectional view of the cap 4 shown in Fig. 8, Fig. 12 is a horizontal cross-sectional view of the cap 4 shown in Fig. 8 taken along line YY in Fig. 9, Fig. 13 is a horizontal cross-sectional view of the cap 4 shown in Fig. 8 taken along line ZZ in Fig. 9, and Fig. 14 is an enlarged cross-sectional view showing the attachment portion of the erasing member 2 of the writing instrument 1 shown in Fig. 1 and the cap 4. Fig. 11 is a cross-sectional view at a position rotated 90 degrees around the central axis with respect to the cross-sectional view shown in Fig. 10.

[0037] When the erasing member 2 is inserted between the support walls 16 of the cap body 4a, the fitting portion 14 is inserted into the fitting hole 2c of the erasing member 2, and the outer circumferential surface of the insertion portion 2a of the erasing member 2 is guided along the inner circumferential surface of the support wall 16. The fitting portion 14 passes through the tapered portion 2g and the small diameter portion 2h of the fitting hole 2c and passes over the locking portion 2j. When the rear end surface of the jaw portion 2f of the erasing member 2 abuts against the front end surface 16b of the support wall 16, the attachment of the erasing member 2 is completed.

[0038] The maximum outer diameter of the fitting part 14 is set to be larger than the minimum inner diameter of the tapered part 2g of the fitting hole 2c, i.e., the inner diameter of the small diameter part 2h, and equal to or smaller than the inner diameter of the large diameter part 2i. Therefore, when the fitting part 14 passes through the tapered part 2g and the small diameter part 2h of the fitting hole 2c, the fitting part 14 or the insertion part 2a of the erasing member 2 is elastically deformed.

[0039] The front end edge 14a of the fitting portion 14 is rounded and has a tapered portion 2g at the entrance when the fitting portion 14 is inserted into the fitting hole 2c, so that the fitting portion 14 can be smoothly inserted into the fitting hole 2c. Furthermore, while the fitting portion 14 is being inserted into the fitting hole 2c, only the outer peripheral surface 14d of the fitting portion 14 moves in the fitting hole 2c while abutting against the inner peripheral surface 2k of the fitting hole 2c. That is, the press-fitting force required for insertion is largely due to the frictional force between the outer peripheral surface 14d of the fitting portion 14 and the inner peripheral surface 2k of the fitting hole 2c, but since the contact area between them is substantially constant, the press-fitting force required during insertion is also substantially constant. Therefore, the eraser 2 can be easily attached to the cap.

[0040] Here, the inner diameters of the tapered portion 2g and the small diameter portion 2h of the fitting hole 2c are set so as to include or abut the two connecting portions 15 when the installation is completed. That is, as described above, the two connecting portions 15 extend at an incline toward the central axis as they go forward, but this inclination is set to be equal to or greater than the inclination of the tapered portion 2g of the fitting hole 2c. Therefore, the connecting portions 15 do not abut against the inner peripheral surface 2k of the fitting hole 2c during the installation of the erasing member 2. On the other hand, by setting the inclinations of both to be equal, the two connecting portions 15 can be inscribed on the inner peripheral surface of the tapered portion 2g when the installation is completed. This makes it possible to realize a strong installation without rattling the erasing member 2.

[0041] As is clear from the relationship between the connection part 15 and the inner peripheral surface 2k of the fitting hole 2c, the insertion with a substantially constant contact area is realized by the presence of a clearance space 17 around the connection part 15, which is formed because the fitting part 14 is supported by the columnar connection part 15. The clearance space 17 is defined by the fitting part 14, the connection part 15, and the inner peripheral surface 2k of the fitting hole 2c of the erasing member 2. The presence of the clearance space 17 reduces frictional resistance during attachment of the erasing member 2 to the cap, making attachment easier.

[0042] After the attachment is completed, the fitting portion 14 is slightly spaced in the axial direction from the stepped locking portion 2j provided in the fitting hole 2c of the erasing member 2. Similarly, the rear end surface of the insertion portion 2a of the erasing member 2 is slightly spaced in the axial direction from the front end portion 4d of the cap body 4a. The engaging protrusion 2d provided on the side surface of the insertion portion 2a of the erasing member 2 elastically deforms to engage with the inner peripheral surface 16a of the support wall 16, making it difficult for the erasing member 2 to come off. Furthermore, in order to ensure the engagement between the engaging protrusion 2d and the inner peripheral surface 16a of the support wall 16 more reliably, a recess 16c having a shape corresponding to the engaging protrusion may be provided on the inner peripheral surface of the support wall 16 at a position corresponding to the engaging protrusion 2d after the attachment is completed.

[0043] When the attachment is completed, the elastic deformation of the fitting portion 14 or the insertion portion 2a of the erasing member 2 at the time of attachment is restored. Therefore, when an attempt is made to remove the erasing member 2 from the cap 4 for the purpose of replacing the erasing member 2, the front end surface of the locking portion 2j of the erasing member 2 and the corner portion 14c at the rear end surface of the fitting portion 14 engage with each other, preventing this. Therefore, a stronger force must be applied to remove the erasing member 2 from the cap 4. This causes the locking portion 2j or the corner portion 14c to elastically deform, releasing the engagement, and making it possible to remove the erasing member 2 from the cap 4.

[0044] It is preferable that the pulling force required to pull the erasing member 2 out of the cap 4 is designed to be larger than the press-fitting force required to attach the erasing member 2 to the cap 4. This can be achieved, for example, by adjusting the inclination or minimum inner diameter of the tapered portion 2g of the fitting hole 2c, the maximum outer diameter of the fitting portion 14, etc.

[0045] The fitting hole 2c of the erasing member 2 may have only the tapered portion 2g, and may not have the small diameter portion 2h and the large diameter portion 2i, i.e., may not have the locking portion 2j. In this case, the fitting portion 14 engages with the tapered portion 2g of the fitting hole 2c by frictional resistance between its outer circumferential surface 14d and the inner circumferential surface of the tapered portion 2g.

[0046] Here, the writing instrument 1 according to one embodiment of the present invention shown in FIG. 1 uses thermochromic ink as the ink. Thermochromic ink refers to ink that maintains a predetermined color (first color) at room temperature (e.g., 25°C), changes to another color (second color) when heated to a predetermined temperature (e.g., 60°C), and then returns to the original color (first color) when cooled to a predetermined temperature (e.g., -5°C). In the writing instrument 1 using thermochromic ink, the second color is made colorless, and the term "erasing" refers to heating a line drawn in the first color (e.g., red) to make it colorless. Therefore, in this embodiment, the erasing member 2 rubs against the paper surface on which the line was drawn to generate frictional heat, which changes the drawn line to colorless, that is, erases it. It should be noted that the second color may be a color other than colorless.

[0047] In the present invention, "erasing" refers to, in addition to the case where the above-mentioned thermochromic ink is used, adsorbing or scraping off written lines, characters, etc. with an erasing member 2 such as an eraser. Therefore, the above and following aspects of the present invention are also applicable to any writing implement that erases written lines with an erasing member 2.

[0048] A writing instrument according to another embodiment of the present invention will be described below. The writing instrument body is the same as the embodiment described above, so a description thereof will be omitted, and only the differences from the embodiment described above will be described.

[0049] FIG. 15 is a perspective view of a cap 24 of another embodiment different from the cap 4 of the writing instrument 1 shown in FIG. 1, and FIG. 16 is a vertical cross-sectional view of the cap 24 shown in FIG. 15. The cap 24 shown in FIG. 15 and FIG. 16 is different from the cap 4 shown in FIG. 2 to FIG. 4 only in that it has a positioning protrusion 24h. The positioning protrusion 24h has a shape complementary to the flat portion 2e provided on the insertion portion 2a of the erasing member 2 when the erasing member 2 is attached to the cap 24. By having the positioning protrusion 24h on the cap 24, it is possible to position the erasing member 2 in a predetermined direction when attached, and the erasing member 2 can be prevented from rotating after attachment. When the cap 24 is made of a transparent or translucent material, it is preferable that the positioning protrusion 24h is provided on the side where the clip portion 4b is located on the inner peripheral surface 16a of the support wall 16, because this creates an aesthetic feeling in terms of the alignment with the clip portion 4b.

[0050] FIG. 17 is a perspective view of a cap 24 to which an erasing member 22 of a different embodiment from the erasing member 2 of the writing instrument shown in FIG. 1 is attached, FIG. 18 is a longitudinal cross-sectional view of the cap 24 shown in FIG. 17, and FIG. 19 is a longitudinal cross-sectional view of the erasing member 22 shown in FIG. 17.

[0051] In this embodiment, the cap 24 is as shown in Figures 15 and 16. The erasing member 22 differs from the erasing member 2 shown in Figures 5 to 7 in that the fitting hole 22c does not penetrate to the erasing portion 22b. That is, although the fitting hole 22c is depicted in a simplified manner in the figures, it has at least a tapered portion, a locking portion, and a large diameter portion in the insertion portion 22a, and the axial length of the large diameter portion is set to a length that receives the fitting portion 14 and the connection portion 15 of the cap. As described above, the fitting hole 22c may have only a tapered portion.

[0052] The front end surface of the erasing portion 22b is provided with a concave recess 22m. The provision of the recess 22m on the front end surface of the erasing portion 22b makes it possible to erase minute areas using the edge of the recess 22m. Furthermore, by holding the erasing member 22 perpendicular to the paper surface or the like on which the lines are drawn, frictional resistance is reduced compared to when the front end surface of the erasing portion is formed into a convex curved surface, making it possible to erase a wide area smoothly.

[0053] FIG. 20 is a perspective view of a cap 24 to which an erasing member 32 of yet another embodiment different from the erasing member 2 of the writing instrument shown in FIG. 1 is attached, FIG. 21 is a perspective view of the erasing member 32 shown in FIG. 20, and FIG. 22 is a front view of the erasing member 32 shown in FIG. 20.

[0054] In this embodiment, the cap 24 is as shown in Figs. 15 and 16. The eraser 32 is the same as the eraser 2 shown in Figs. 5 to 7 in terms of the insertion portion 2a and the fitting hole 2c, and is different only in the outer shape of the eraser 32b. The eraser 32b has a cross-sectional shape that is circular at the rear end face, but gradually changes to an elliptical shape with a ratio of the major axis to the minor axis gradually increasing from the rear end face to the front end face. The length of the major axis of the ellipse at the front end face of the eraser 32b is shorter than the diameter of the circle at the rear end face of the eraser 32b. By making the cross-sectional shape of the eraser 32b elliptical, when erasing a drawn line or the like, it is possible to realize different erasing widths, i.e., areas that can be rubbed at once, depending on whether the major axis direction is parallel to the paper surface or the minor axis direction is parallel to the paper surface or the like, or between them.

[0055] FIG. 23 is a perspective view of a cap 24 to which an erasing member 42 of yet another embodiment different from the erasing member 2 of the writing instrument shown in FIG. 1 is attached, FIG. 24 is a perspective view of the erasing member 42 shown in FIG. 23, and FIG. 25 is a front view of the erasing member 42 shown in FIG. 23.

[0056] In this embodiment, the cap 24 is as shown in Figs. 15 and 16. The eraser 42 is the same as the eraser 2 shown in Figs. 5 to 7 in terms of the insertion portion 2a and the fitting hole 2c, and is different only in the outer shape of the eraser 42b. The cross-sectional shape of the eraser 42b is circular at the rear end face, but hexagonal at the front end face, and has an outer shape that gradually changes from circular to hexagonal from the rear end face to the front end face. The hexagonal shape of the front end face of the eraser 42b is rounded at its corners, and preferably, one side of the hexagon is formed so as to be parallel to the flat portion 2e of the insert portion 2a. The hexagonal shape of the front end face of the eraser 2b makes it possible to erase minute places using the side portion 42n and the corner portion 42o. The shape of the front end face of the eraser 42b is not limited to a hexagon, and may be other polygonal shapes such as a triangle or a rectangle.

[0057] FIG. 26 is a perspective view of a cap 24 to which an erasing member 52 of yet another embodiment different from the erasing member 2 of the writing instrument shown in FIG. 1 is attached, FIG. 27 is a perspective view of the erasing member 52 shown in FIG. 26, and FIG. 28 is a front view of the erasing member 52 shown in FIG. 26.

[0058] In this embodiment, the cap 24 is as shown in Figs. 15 and 16. The eraser 52 is the same as the eraser 2 shown in Figs. 5 to 7 in terms of the insertion portion 2a and the fitting hole 2c, and differs only in the outer shape of the eraser 52b. When the eraser 52b is considered as a half body split vertically, the first half body 52p has a truncated cone shape, and the second half body 52q has a truncated hexagonal pyramid shape. A flat portion 2e, which is positioned by a positioning protrusion 24h of the cap body 4a, is provided on the first half body 52p side of the inserting portion 2a so that the first half body is disposed on the clip portion 4b side of the cap 24.

[0059] By placing the first half 52p on the clip portion 4b side of the cap, the hexagonal pyramid-shaped surface of the second half 52q becomes easier to use. That is, when a user holds the cap 24 and performs an erasing operation, the index finger and thumb are placed on both sides of the clip portion 4b to avoid the clip portion 4b, and the middle finger is placed on the outer peripheral surface of the cap body 4a on the opposite side to the clip portion 4b to hold the cap 24. Therefore, in this holding state, the hexagonal pyramid-shaped surface of the second half 52q faces the paper.

[0060] The first half 52p has the same shape as the erasing section 2b shown in Figs. 5 to 7. The second half 52q has three flat surfaces 52r because it is a half having a hexagonal pyramid shape. Therefore, erasing on a narrow surface is possible by erasing on the first half 52p of the erasing section 52b. On the other hand, when erasing on the second half 52q of the erasing section 52b, erasing on a wider surface is possible by using each flat surface 52r than when using the first half 52p. In addition, erasing on a smaller area is possible by using the peaks 52s, which are the connecting parts of each flat surface, or the connecting parts 52t between the peaks and the front end surface.

[0061] FIG. 29 is a perspective view of a cap 24 to which an erasing member 62 of yet another embodiment different from the erasing member 2 of the writing instrument shown in FIG. 1 is attached, FIG. 30 is a perspective view of the erasing member 62 shown in FIG. 29, and FIG. 31 is a front view of the erasing member 62 shown in FIG. 29.

[0062] In this embodiment, the cap 24 is as shown in Figs. 15 and 16. The eraser 62 is the same as the eraser 2 shown in Figs. 5 to 7 in terms of the insertion portion 2a and the fitting hole 2c, and differs only in the outer shape of the eraser 62b. The eraser 62b is configured by replacing both sides of the second half 52q shown in Figs. 26 to 28 with the truncated cone shape of the first half 52p. Therefore, the eraser 62b is composed of a truncated cone-shaped portion 62u and a truncated hexagonal pyramid-shaped portion 62v. A flat portion 2e, which is positioned by a positioning protrusion 24h of the cap body 4a, is provided on the truncated cone-shaped portion 62u side of the inserting portion 2a so that the truncated cone-shaped portion 62u is disposed on the clip portion 4b side of the cap 24.

[0063] By arranging the truncated cone-shaped portion 62u on the clip portion 4b side of the cap 24, the surface of the truncated hexagonal pyramid-shaped portion 62v can be easily used. That is, when a user holds the cap 24 to perform an erasing operation, the user usually places the index finger and thumb on both sides of the clip portion 4b to avoid the clip portion 4b, and holds the cap 24 by placing the middle finger on the part of the outer circumferential surface of the cap body 4a opposite to the side where the clip portion 4b is located. Therefore, in this holding state, the surface of the truncated hexagonal pyramid-shaped portion 62v faces the paper.

[0064] Erasing with the truncated cone-shaped portion 62u of the erasing portion 62b allows erasing on a narrow surface. On the other hand, when erasing with the truncated hexagonal pyramid-shaped portion 62v of the erasing portion 62b, erasing on a wider surface is possible by using one surface than when the truncated cone-shaped portion 62u is used. In addition, erasing on a smaller area is possible by using the peaks 62w, which are the connecting portions of the surfaces, or the connecting portion 62x between the peaks 62w and the front end surface.

[0065] In the above-described embodiment of the erasing member of the present invention, the erasing member is attached to the front end of the cap, but the erasing member can also be attached to the rear end of the writing implement body in the same manner.

[0066] FIG. 32 is a vertical cross-sectional view of a writing instrument 100 according to a second embodiment having an erasing member 2 according to one aspect of the present invention. The writing instrument 100 is a ballpoint pen type writing instrument, and has a writing instrument body 3 having a refill 5 and a cylindrically extending barrel 6, and a cap 104. The barrel 6 has a cylindrical front barrel 7 and a rear barrel 8 whose front end is screwed into the rear end of the front barrel 7. The writing instrument 100 according to this embodiment differs from the writing instrument 1 according to the first embodiment described above only in the outer shape of the cap, particularly the shape of the clip part. Therefore, the following description will particularly focus on the clip part, and the other parts will be omitted. Note that the cap 104 can be configured to be able to attach an erasing member attached to the cap 4 shown in FIG. 4, for example, and can be configured to be able to attach an erasing member attached to the cap 24 shown in FIG. 15, for example.

[0067] Figure 33 is an oblique view of the cap 104 of the writing instrument 100 shown in Figure 32, Figure 34 is a plan view of the cap 104 shown in Figure 33, Figure 35 is a side view of the cap 104 shown in Figure 33, Figure 36 is a longitudinal cross-sectional view of the cap 104 shown in Figure 33, and Figure 37 is a cross-sectional view of the cap 104 shown in Figure 33 along line SS in Figure 35.

[0068] The cap 104 has a cap body 104a, a clip portion 104b, and, in this embodiment, an erasing member 2. The cap body 104a is a cylindrical member, and the clip portion 104b is integrally provided on its side via a connecting portion 104c. The clip portion 104b is configured to have elasticity so that articles such as documents and clothes can be clamped between the cap body 104a and the clip portion 104b. Therefore, examples of materials for forming the cap body 104a and the clip portion 104b include synthetic resins such as polycarbonate and acrylonitrile butadiene styrene. As described above, it is preferable to form them from a material harder than the front barrel 7.

[0069] The cap 104 is characterized in that the clip portion 104b is a substantially rectangular plate-like member extending in the axial direction over substantially the entire length of the clip body 104a. The rear end surface of the clip portion 104b is curved to improve the feel, as shown in FIG. 34. In addition, a guide surface 104d, which is a plane perpendicular to the central axis, is formed in the center of the front end surface of the clip portion 104b, and the front end surfaces on both sides of the guide surface 104d are curved like the rear end surface. Each edge of the clip portion 104b is chamfered. Note that the guide surface 104d does not have to be perpendicular to the central axis. For example, as will be described later with reference to FIG. 38, it may be an inclined surface that matches the paper surface that faces when erasing.

[0070] As is clear from the plan view of FIG. 34, the width W of the clip portion 104b is approximately the same as the diameter of the cylindrical cap body 104a. Therefore, from the user's viewpoint, the cap body 104a is almost hidden by the clip portion 104b, and only the clip portion 104b and the erasing member 2 are visible. That is, compared to a conventional clip portion, for example, the clip portion 4b of the cap 4 shown in FIG. 2, the clip portion 104b of the cap 104 has a wide, extensive and smooth surface. Therefore, by applying decoration such as transfer printing to the surface, the design can be improved and the appeal to users can be increased. In addition, by attaching a rubber elastic material such as rubber or elastomer to the above surface, an erasing surface wider than the erasing member 2 is formed, so that it is possible to use the area to be erased.

[0071] The connecting portion 104c connecting the cap body 104a and the clip portion 104b has a T-shaped cross section as shown in Fig. 37. This increases the strength of the clip portion 104b against a circumferential force (the vertical direction in Fig. 37). Therefore, even if a circumferential force is applied to the clip portion 104b during use by a user, damage to the connecting portion 104c is prevented.

[0072] FIG. 38 is a diagram showing a state of use of the cap 104 to which the erasing member 2 of the writing instrument 100 shown in FIG. 32 is attached during erasing. As shown in FIG. 38, when erasing, the cap 104 is slid along the guide surface 104d while pressing the flat guide surface 104d of the clip portion 104b against the paper surface, thereby enabling erasure of handwriting in a fixed width. At this time, if the cap 104 is slid while pressing the guide surface 104d of the clip portion 104b against a guide member such as a ruler J, a more stable erasing operation is possible, and erasing of a long range with a fixed width can be easily performed. Furthermore, by sliding the cap 104 while pressing the guide surface 104d of the clip portion 104b against the paper surface and abutting the wide surface of 104b against the inclined surface Ja provided on the ruler J, a more stable erasing operation is possible.

[0073] In addition, by adjusting the shape of the erasing member 2, the axial position of the clip portion 104b relative to the cap body 104a, the shape of the guide surface 104d, etc., it is possible to adjust the angle A formed between the paper surface and the central axis of the writing instrument 100 during the erasing operation. This angle A is preferably in the range of 40 to 80 degrees.

[0074] In addition to the above-mentioned effects, since the width W of the clip portion 104b and the diameter of the cap body 104a are substantially the same, for example, when the writing instrument 100 is placed on a desk or the like with the wide flat surface of the clip portion 104b facing up, the writing instrument 100 rotates and the side surface of the clip portion 104b comes into contact with the desk or the like, so that the writing instrument 100 can be maintained in a state of being just horizontal. This provides the effect that the barrel 6 is easy to grip when picking up the writing instrument 100. Also, the writing instrument 100 can always be prevented from rolling.

[0075] Furthermore, by extending the clip portion 104b to the center of gravity of the writing instrument and by having the clip portion 104b of the above-mentioned structure on the cap 104, for example, when the writing instrument 100 is placed on a desk or the like with the wide flat surface of the clip portion 104b facing down, the rear end of the writing instrument 100 does not touch the desk and can be stabilized in a floating state. Therefore, an effect is achieved that the barrel 6 is easy to grip when picking up the writing instrument 100.

[0076] The structure of the clip portion 104b described in this embodiment is applicable not only to the cap, but also to attachment to the front barrel and the rear barrel. [Explanation of symbols]

[0077] 1 writing implements 2 Erasing material 2c Mating hole 3 Writing instrument body 4 Cap 14 Fitting part 15 Connection 16 Supporting wall 17 Interstitial Space

Claims

[Claim 1] A thermochromic writing instrument comprising: a barrel containing thermochromic ink therein and having a writing section at its front end from which the thermochromic ink can be ejected; and a cap removably attached to the writing section side of the barrel, the cap being provided with an erasing member, the erasing member rubbing handwriting of the thermochromic ink with the erasing member, and the frictional heat generated by the friction causes the handwriting to thermochromic, A clip portion is integrally provided on a side surface of the cap via a connecting portion, The clip portion is a substantially rectangular plate-like member extending in an axial direction, The width of the clip portion and the diameter of the cap are substantially the same, and the clip portion extends to the center of gravity of the thermochromic writing instrument, A thermochromic writing instrument in which the outer surface of the cap narrows toward the front, the center of gravity of the thermochromic writing instrument is located inside the cap when the cap is attached to the writing portion side of the barrel, and when the thermochromic writing instrument is placed on a horizontal support surface with the cap attached to the writing portion side of the barrel, the outer surface of the clip portion comes into contact with the horizontal support surface, and the outer surface and rear end of the barrel rearward of the cap are not in contact with the horizontal support surface.

Images