JP2024065887A - Thermochromic writing implements - Google Patents

Abstract

[Problem] To provide a thermochromic writing implement that prevents damage to an inner fitting portion, reliably ensures the fitting performance between an inner cylinder and an outer cylinder, and improves insertability of the inner cylinder into an outer cylinder. [Solution] A writing implement body 2 having a pen tip 21 that contains thermochromic ink and can eject the ink, or a cap body 7 that can be attached to the pen tip 21 of the writing implement body 2. The writing implement body 2 or the cap body 7 includes an outer cylinder 4 and an inner cylinder 5 that is fitted to the inner surface of the outer cylinder 4. An outer fitting portion 51 is formed on the outer surface of the inner cylinder 5. An inner fitting portion 43 that fits with the outer fitting portion 51 is formed on the inner surface of the outer cylinder 4. An abutment wall portion 54 facing rearward is formed on the outer surface of the inner cylinder 5. A regulating wall portion 44 that abuts against the abutment wall portion 54 in the front-rear direction is integrally formed on the inner surface of the outer cylinder 4. The restricting wall portion 44 is provided forward of the inner fitting portion 43 [selected figure] FIG. 1

Description

The present invention relates to a thermochromic writing instrument. In particular, the present invention relates to a thermochromic writing instrument having a friction body, the rear end of the writing instrument body or the cap body of the thermochromic writing instrument being constituted by an outer cylinder, and an inner cylinder being fixed to the inner surface of the outer cylinder.

Patent Document 1 discloses a writing instrument in which an inner seal is formed on the inner surface of a cylinder constituting the main body of the writing instrument, which fits airtight with the outer surface of a stopper, and a restricting wall is integrally formed on the inner surface of the cylinder behind the inner seal, which abuts against the rear surface of the stopper in the front-to-rear direction and prevents the stopper from moving backward.

Patent document 2 also discloses a writing instrument cap in which an inner fitting portion is formed on the inner surface of the cap body, and a regulating wall portion having an inner diameter smaller than the inner diameter of the inner fitting portion is integrally formed on the inner surface of the cap body rearward of the inner fitting portion, and the inner fitting portion is fitted into an outer fitting portion on the outer surface of the inner cap, and the rear surface of the inner cap is abutted against the regulating wall portion.

Patent Application No. 2009-106070 Patent Application No. 2008-143367

In the writing implements of Patent Documents 1 and 2, the regulating wall is provided behind the inner fitting portion, so that when the inner barrel (stopper, inner cap) is inserted into the outer barrel (barrel, cap body), the rear portion of the inner barrel (the portion that abuts against the regulating wall portion) may get caught and scratch the inner fitting portion, resulting in a risk of not being able to achieve proper fitting performance. For example, in Patent Document 1, if the stopper is inserted at an angle when inserted into the barrel, the rear end of the stopper may get caught on the inner seal portion. In Patent Document 2, if the inner cap is inserted at an angle when inserted into the cap body, the rear end of the outer fitting portion of the inner cap may get caught on the inner fitting portion.

In particular, in Patent Document 1, the cylinder and the plug are airtightly fitted together, so if the inner seal is damaged, there is a risk that appropriate airtightness will not be achieved.

Furthermore, because the restricting wall portion is provided rearward of the inner fitting portion, it was necessary to make the outer diameter of the inner cylinder body rearward of the inner fitting portion larger than the inner diameter of the restricting wall portion. As the outer diameter of the rear portion of the inner cylinder body is larger, there was a risk that the insertability of the inner cylinder body into the outer cylinder body would be reduced.

The present invention aims to solve the above-mentioned problems of the conventional art by providing a thermochromic writing instrument that prevents scratches on the inner fitting portion, reliably ensures the fitting performance of the inner and outer barrels, and improves the insertability of the inner barrel into the outer barrel. In particular, when the outer barrel requires airtight performance, a thermochromic writing instrument is provided that can reliably ensure airtightness between the outer surface of the inner barrel and the inner surface of the outer barrel. In this invention, in the writing instrument body, "front" refers to the nib side, and "rear" refers to the opposite side. In the cap body, "front" refers to the opening side of the cap (i.e., the nib insertion side), and "rear" refers to the opposite side.

A first aspect of the present invention is a thermochromic writing instrument comprising a writing instrument body having a thermochromic ink built therein and a pen tip capable of discharging the ink, or a cap body that can be attached to the pen tip of the writing instrument body, and a friction body that is attached to the writing instrument body or the cap body and rubs the handwriting of the thermochromic ink,
The writing instrument body or the cap body includes an outer cylinder body and an inner cylinder body fitted to the inner surface of the outer cylinder body,
The friction body is attached to the rear end of the outer cylinder,
An outer fitting portion is formed on the outer surface of the inner cylinder, and an inner fitting portion that fits with the outer fitting portion is formed on the inner surface of the outer cylinder,
The present invention is characterized in that a rearward-facing abutment wall portion is formed on the outer surface of the inner cylinder, and a control wall portion is integrally formed on the inner surface of the outer cylinder that abuts against the abutment wall portion in the front-to-rear direction and prevents the inner cylinder from moving rearward, and the control wall portion is located forward of the inner fitting portion.

The writing instrument of the first invention, with the above configuration, can prevent the inner cylinder from getting caught on the inner surface of the outer cylinder and damaging the inner fitting portion when the inner cylinder is inserted into the outer cylinder. In addition, since the movement of the inner cylinder is restricted by the restricting wall portion in front of the inner fitting portion, the outer diameter of the inner cylinder behind the outer fitting portion can be set as desired, improving the insertability of the inner cylinder into the outer cylinder.

A second aspect of the present invention is a thermochromic writing instrument comprising a writing instrument body having a thermochromic ink built therein and a pen tip capable of discharging the ink, or a cap body that can be attached to the pen tip of the writing instrument body, and a friction body that is attached to the writing instrument body or the cap body and rubs the handwriting of the thermochromic ink,
The writing instrument body or the cap body includes an outer cylinder body and an inner cylinder body fitted to the inner surface of the outer cylinder body,
the outer cylinder body has an inner hole penetrating in the front-rear direction, and a front end opening and a rear end opening communicating with the inner hole,
The friction body is attached to the rear end opening of the outer cylinder body,
An outer fitting portion is formed on an outer surface of the inner cylinder, and an inner fitting portion that fits airtightly with the outer fitting portion is formed on an inner surface of the outer cylinder,
The present invention is characterized in that a rearward-facing abutment wall portion is formed on the outer surface of the inner cylinder, and a control wall portion is integrally formed on the inner surface of the outer cylinder that abuts against the abutment wall portion in the front-to-rear direction and prevents the inner cylinder from moving rearward, and the control wall portion is located forward of the inner fitting portion.

The thermochromic writing instrument of the second invention, with the above-mentioned configuration, can prevent the inner cylinder from getting caught on the inner surface of the outer cylinder when inserting the inner cylinder into the outer cylinder, causing damage to the inner fitting portion, and can reliably ensure airtightness between the outer surface of the inner cylinder and the inner surface of the outer cylinder. In addition, since the movement of the inner cylinder is restricted by the restricting wall portion in front of the inner fitting portion, the outer diameter of the rear end of the inner cylinder can be set as desired, improving the insertability of the inner cylinder into the outer cylinder.

A third aspect of the present invention is a thermochromic writing instrument comprising: a writing instrument body having a thermochromic ink built therein and a pen tip capable of discharging the ink; a cap body that can be attached to the pen tip of the writing instrument body; and a friction body that is attached to the cap body and rubs the writing of the thermochromic ink,
The cap body includes an outer cylinder and an inner cylinder fitted to the inner surface of the outer cylinder,
The friction body is attached to the rear end of the outer cylinder,
An outer fitting portion is formed on the outer surface of the inner cylinder, and an inner fitting portion that fits with the outer fitting portion is formed on the inner surface of the outer cylinder,
a rearward-facing abutment wall portion is formed on an outer surface of the inner cylinder body, and a restricting wall portion is integrally formed on an inner surface of the outer cylinder body forward of the inner fitting portion, the restricting wall portion abutting against the abutment wall portion in the front-rear direction and preventing the inner cylinder body from moving rearward;
An annular seal portion is provided at the front end of the inner surface of the inner cylinder and is airtightly fitted with the writing instrument body,
The outer fitting portion is provided rearward of the contact wall portion, and the contact wall portion is provided rearward of the annular seal portion.

The thermochromic writing instrument of the third invention of the present application, with the above-mentioned configuration, can maintain the airtight performance of the cap body as a cap, while preventing the inner cylinder from getting caught on the inner surface of the outer cylinder when inserting the inner cylinder into the outer cylinder, causing damage to the inner fitting portion.

The fourth invention of the present application is any one of the first to third inventions, in which a flange portion protruding radially outward is provided on the outer surface of the inner cylinder forward of the outer fitting portion, and the abutment wall portion is preferably provided at the rear end of the flange portion.

The thermochromic writing instrument of the fourth invention, with the above-mentioned configuration, can prevent the flange with a large outer diameter from getting caught and damaging the inner fitting portion when inserting the inner cylinder into the outer cylinder. In addition, since the flange with a large outer diameter is located forward of the outer fitting portion, the insertability of the inner cylinder into the outer cylinder is improved.

The thermochromic writing instrument of the present invention prevents scratches on the inner fitting portion, reliably ensures the fitting performance between the inner and outer barrels, and improves the insertability of the inner barrel into the outer barrel.

1 is a vertical cross-sectional view showing a first embodiment of the present invention. FIG. 2 is an enlarged longitudinal sectional view of a main portion of FIG. 1 . FIG. 3 is a cross-sectional view taken along line A-A of FIG. 2 . FIG. 2 is a vertical cross-sectional view of the outer cylindrical body to which the inner cylindrical body and the friction body are fixed in FIG. 1 . FIG. 2 is an enlarged longitudinal sectional view of a main portion showing a modification of FIG. 1 . 1 is an enlarged longitudinal sectional view showing a main part of a second embodiment of the present invention, in which the two-dot chain line indicates a writing instrument body. FIG. 7 is an enlarged longitudinal sectional view of a main portion showing a modification of FIG. 6 .

First Embodiment
1 to 5 show a first embodiment of the present invention. A thermochromic writing implement 1 of this embodiment comprises a writing implement body 2 including a pen tip 21, a pen tip holding tube 3 to which the pen tip 21 is fixed, an outer cylinder 4 connected to the rear end of the pen tip holding tube 3, a friction body 6 fixed to a rear end opening 42 of the outer cylinder 4, an inner cylinder 5 fixed to the inner surface of the outer cylinder 4 in front of the friction body 6, and an ink occlusion body 22 accommodated inside the outer cylinder 4 and inside the pen tip holding tube 3 in front of the inner cylinder 5.

Pen tip The pen tip 21 is made of a resin-processed fiber body. Other examples of the pen tip 21 include a ballpoint pen tip, a heat-fused fiber bundle body, a felt body, a pipe-shaped pen body, a fountain pen-type flat pen body having a slit at the tip, a brush pen body, a synthetic resin porous foam body, and a synthetic resin extrusion molded body having an axial ink guide path.

Ink Occluder The ink occluder 22 may be any material having continuous pores that can be impregnated with ink (i.e., a porous material), such as a heat-sealed fiber bundle, a resin-processed fiber bundle, a resin-processed felt, a needle-punched felt, or an open-celled synthetic resin. The ink occluder 22 may also be provided with an outer skin made of a synthetic resin film or the like on its outer periphery. The rear end of the pen tip 21 is pierced and connected to the front surface of the ink occluder 22.

The ink occlusion body 22 is impregnated with thermochromic ink. The handwriting formed with the thermochromic ink can be discolored by rubbing it with the rear end of the friction body 6.

Pen tip holding tube The pen tip holding tube 3 is obtained by injection molding of synthetic resin. The pen tip 21 is press-fitted and fixed to the tapered front end of the pen tip holding tube 3, and the front end of the pen tip 21 protrudes forward from the tapered front end. The front part of the ink absorbing body 22 is housed inside the pen tip holding tube 3, and the rear end of the pen tip 21 is inserted and connected to the front end of the ink absorbing body 22. The rear end opening of the pen tip holding tube 3 is connected to the front end opening 41 of the outer cylinder 4 by airtight fitting. Between the outer surface of the pen tip 21 and the inner surface of the pen tip holding tube 3, an air passage (not shown) is formed that allows communication between the inside of the pen tip holding tube 3 and the outside air.

External cylinder body The external cylinder body 4 is a cylinder obtained by injection molding of synthetic resin. The external cylinder body 4 has an inner hole penetrating in the axial direction, and the inner hole communicates with the outside through a front end opening 41 and a rear end opening 42. The inner surface of the front end opening 41 of the external cylinder body 4 is connected to the outer surface of the rear end opening 42 of the pen tip holding tube 3 by airtight fitting.

A ring-shaped inner fitting portion 43 is formed on the inner surface of the rear part of the outer cylinder body 4. The inner fitting portion 43 is made of a ring-shaped smooth surface or a ring-shaped protrusion. The inner diameter C of the inner fitting portion 43 is set to be smaller than the inner diameter B of the outer cylinder body 4.

A restricting wall portion 44 is integrally formed on the inner surface of the outer cylinder body 4. The restricting wall portion 44 is an annular step that occurs between the inner surface of the outer cylinder body 4 and the inner fitting portion 43. The front end surface of the restricting wall portion 44 is formed perpendicular to the axis.

An inward protrusion 45 is integrally formed on the inner surface of the outer cylinder 4 behind the restricting wall portion 44 (i.e., the inner surface of the rear end opening 42 of the outer cylinder 4). The inward protrusion 45 is composed of an annular protrusion or multiple dispersed protrusions. The inner diameter (minimum inner diameter) D of the inward protrusion 45 is formed to be smaller than the inner diameter C of the inner fitting portion 43. The corner of the front end of the inward protrusion 45 is formed at an acute angle or a right angle. The rear surface of the inward protrusion 45 has an inclined surface whose inner diameter gradually increases toward the rear.

In this embodiment, the outer cylinder 4 only needs to constitute at least the rear end of the writing instrument body 2, and the outer cylinder 4 may constitute substantially the entire writing instrument body 2, or the outer cylinder 4 may constitute only the rear end of the writing instrument body. In addition, in the present invention, the configuration for fixing the outer cylinder 4 to the pen tip 21 may be, for example, a configuration in which the pen tip 21 is directly fixed to the outer cylinder 4, or a configuration in which the pen tip 21 is fixed to the outer cylinder 4 via another member such as the pen tip holding tube 3.

The inner cylinder 5 is a bottomed cylinder having an open front end and a closed rear end, and is obtained by injection molding of a synthetic resin.

An annular outer fitting portion 51 is integrally formed on the outer surface of the inner cylinder 5. The outer fitting portion 51 is an annular protrusion or an annular smooth surface. The outer fitting portion 51 has an outer diameter slightly larger than the inner diameter C of the inner fitting portion 43. This ensures a reliable airtight fit between the outer fitting portion 51 and the inner fitting portion 43.

A notch 52 that opens forward and penetrates radially is formed in the front end surface of the inner cylinder 5. The rear end surface of the ink occlusion body 22 abuts against the front end surface of the inner cylinder 5. The notch 52 allows ventilation between the rear end surface of the ink occlusion body 22 and the outside air.

A flange 53 protruding radially outward is provided on the outer surface of the inner cylinder 5 forward of the outer fitting portion 51. The flange 53 consists of an annular protrusion or multiple dispersed protrusions. The outer diameter of the flange 53 is set to be the same as or smaller than the inner diameter B of the outer cylinder 4. An abutment wall 54 is integrally formed with the rear end of the flange 53. The abutment wall 54 is a surface perpendicular to the axis. The outer diameter of the rear end of the abutment wall 54 is set to be larger than the outer diameter of the outer fitting portion 51.

The outer diameter of the inner cylinder 5 rearward from the outer fitting portion 51 gradually decreases toward the rear. In this embodiment, the rear end of the inner cylinder 5 has a truncated cone shape. Since the outer diameter of the inner cylinder 5 decreases toward the rear, the insertability of the inner cylinder 5 into the outer cylinder 4 is improved.

The restricting wall portion 44 may be shaped so that the inner diameter gradually decreases toward the rear. As shown in FIG. 5, by making the restricting wall portion 44 tapered, the insertability of the inner cylinder body 5 into the outer cylinder body 4 is further improved. When the restricting wall portion 44 is tapered, the restricting wall portion 44 and the flange portion 53 abut in a line contact.

Friction body The friction body 6 is composed of a large diameter portion and a small diameter portion that is integrally connected to the front of the large diameter portion, and is integrally formed from an elastic material. The friction body 6 is formed from an elastic material such as synthetic rubber or elastomer. In this embodiment, a friction-discoloring member that rubs the surface of handwriting formed with thermochromic ink to thermally discolor the handwriting is used as the friction body 6. Other examples of the friction body 6 made of elastic material include erasers. The friction body 6 is inserted into the rear end opening of the outer cylinder 4 from the rear toward the front.

The rear surface of the large diameter portion has a convex curved shape. A shoulder portion is formed at the front end of the large diameter portion so as to be able to abut against the open end of the rear end opening 42 of the outer cylinder 4 (specifically, the rear end of the outer cylinder 4). The maximum outer diameter of the large diameter portion is set to be larger than the inner diameter of the rear end opening 42 of the outer cylinder 4 and smaller than the outer diameter of the rear end of the outer cylinder 4.

An annular outward protrusion 61 is integrally formed on the outer circumferential surface of the front end of the small diameter portion. The front surface of the outward protrusion 61 has an inclined surface (i.e., a conical surface) whose outer diameter gradually increases toward the rear. The rear end of the outward protrusion 61 has a right-angled or acute-angled corner.

The outer diameter (maximum outer diameter) of the outward protrusion 61 is formed larger than the inner diameter D (minimum inner diameter) of the inward protrusion 45, so that the outward protrusion 61 and the inward protrusion 45 can be reliably locked and prevented from coming off. The outer diameter (maximum outer diameter) of the outward protrusion 61 is formed smaller than the inner diameter of the rear end opening 42 of the outer cylindrical body 4 behind the inward protrusion 45, so that the outward protrusion 61 and the inner surface of the rear end opening of the outer cylindrical body 4 behind the inward protrusion 45 are maintained in a non-engaged state, and the friction body 6 can be smoothly inserted until just before the outward protrusion 61 rides over the inward protrusion 45. When the friction body 6 is completely inserted into the rear end opening 42 of the outer cylindrical body 4 (when the over-engagement is completed), the outer surface of the friction body 6 behind the outward protrusion 61 and the inward protrusion 45 are engaged.

When the friction body 6 has been completely inserted into the rear end opening 42 of the outer tube body 4 (when the over-riding fit has been completed), the rear end of the outward projection 61 (i.e., the maximum outer diameter portion) is located forward of the front end of the inward projection 45 (i.e., the minimum inner diameter portion), and an axial gap is formed between the front end of the inward projection 45 and the rear end of the outward projection 61. As a result, when the outward projection 61 rides over the inward projection 45 from rear to front, the outward projection 61 can reliably ride over the inward projection 45 even if the sliding between the outward projection 61 and the inward projection 45 is poor.

In addition, when the friction body 6 is completely inserted into the rear end opening 42 of the outer cylindrical body 4 (when the over-riding fitting is complete), a radial gap is formed between the outer surface of the outward protrusion 61 and the inner surface of the outer cylindrical body 4. As a result, when the outward protrusion 61 rides over the inward protrusion 45 from rear to front, even if the outward protrusion 61 and the inward protrusion 45 do not slide easily, the outward protrusion 61 can reliably ride over the inward protrusion 45.

The thermochromic writing instrument 1 of this embodiment is a thermochromic writing instrument that includes a writing instrument body 2 having a pen tip 21 capable of discharging thermochromic ink, or a cap body 7 that can be attached to the pen tip 21 of the writing instrument body 2, and is attached to the writing instrument body 2 or the cap body 7 and has a friction body 6 that rubs the handwriting of the thermochromic ink. The writing instrument body 2 or the cap body 7 includes an outer tube 4 and an inner tube 5 that is fitted to the inner surface of the outer tube 4, a friction body 6 is attached to the rear end of the outer tube 4, and a friction body 6 is attached to the outer surface of the inner tube 5. The outer fitting portion 51 is formed, the inner surface of the outer cylinder 4 is formed with an inner fitting portion 43 that fits with the outer fitting portion 51, the outer surface of the inner cylinder 5 is formed with a rearward-facing abutment wall portion 54, and the inner surface of the outer cylinder 4 is integrally formed with a regulating wall portion 44 that abuts against the abutment wall portion 54 in the front-rear direction and prevents the inner cylinder 5 from moving rearward. The regulating wall portion 44 is provided forward of the inner fitting portion 43, so that when the inner cylinder 5 is inserted into the outer cylinder 4, the inner fitting portion 43 can be prevented from being scratched by the inner surface of the outer cylinder 4. In addition, since the regulating wall portion 44 forward of the inner fitting portion 43 restricts the movement of the inner cylinder 5, the outer diameter of the inner cylinder 5 rearward of the outer fitting portion 51 can be set arbitrarily, improving the insertability of the inner cylinder 5 into the outer cylinder 4.

The thermochromic writing instrument 1 of this embodiment is a thermochromic writing instrument that includes a writing instrument body 2 having a pen tip 21 that contains thermochromic ink and can eject the ink, or a cap body 7 that can be attached to the pen tip 21 of the writing instrument body 2, and is attached to the writing instrument body 2 or the cap body 7 and includes a friction body 6 that rubs the handwriting of the thermochromic ink. The writing instrument body 2 or the cap body 7 includes an outer tube 4 and an inner tube 5 that is fitted to the inner surface of the outer tube 4, the outer tube 4 has an inner hole that penetrates in the front-to-rear direction, and a front end opening 41 and a rear end opening 42 that communicate with the inner hole, and the rear end opening 42 of the outer tube 4 is provided with the friction body. The outer surface of the inner cylinder 5 is formed with an outer fitting portion 51, the inner surface of the outer cylinder 4 is formed with an inner fitting portion 43 that fits airtight with the outer fitting portion 51, the outer surface of the inner cylinder 5 is formed with a rearward-facing abutment wall portion 54, and the inner surface of the outer cylinder 4 is integrally formed with a regulating wall portion 44 that abuts against the abutment wall portion 54 in the front-rear direction and prevents the inner cylinder 5 from moving rearward. The regulating wall portion 44 is provided forward of the inner fitting portion 43, so that when the inner cylinder 5 is inserted into the outer cylinder 4, the inner fitting portion 43 is prevented from being scratched by the inner surface of the outer cylinder 4, and airtightness between the outer surface of the inner cylinder 5 and the inner surface of the outer cylinder 4 can be reliably ensured. In addition, since the regulating wall portion 44 forward of the inner fitting portion 43 restricts the movement of the inner cylinder 5, the outer diameter of the rear end of the inner cylinder 5 can be set arbitrarily, improving the insertability of the inner cylinder 5 into the outer cylinder 4.

The thermochromic writing instrument 1 of this embodiment has a flange 53 that protrudes radially outward on the outer surface of the inner cylinder 5 forward of the outer fitting 51, and an abutment wall 54 is provided at the rear end of the flange 53, which prevents the flange 53, which has a larger outer diameter, from getting caught and scratching the inner fitting 43 when the inner cylinder 5 is inserted into the outer cylinder 4. In addition, because the flange 53, which has a larger outer diameter, is provided forward of the outer fitting 51, the insertability of the inner cylinder 5 into the outer cylinder 4 is improved.

Second Embodiment
6 to 8 show a second embodiment of the present invention. The thermochromic writing instrument 1 of this embodiment comprises a cap body 7 including an outer cylinder 4, a friction body 6 fixed to the rear end opening 42 of the outer cylinder 4, and an inner cylinder 5 fixed to the inner surface of the outer cylinder 4 in front of the friction body 6.

The outer cylinder 4 is a cylindrical body obtained by injection molding of synthetic resin. The outer cylinder 4 has an inner hole passing through it in the axial direction, and the inner hole communicates with the outside through a front end opening 41 and a rear end opening 42.

A ring-shaped inner fitting portion 43 is formed on the inner surface of the rear part of the outer cylinder body 4. The inner fitting portion 43 is made of a ring-shaped smooth surface or a ring-shaped protrusion. The inner diameter C of the inner fitting portion 43 is set to be smaller than the inner diameter B of the outer cylinder body 4.

A restricting wall portion 44 is integrally formed on the inner surface of the outer cylinder body 4. The restricting wall portion 44 is an annular step that occurs between the inner surface of the outer cylinder body 4 and the inner fitting portion 43. The front end surface of the restricting wall portion 44 is formed perpendicular to the axis.

An inward protrusion 45 is integrally formed on the inner surface of the outer cylinder 4 behind the restricting wall portion 44 (i.e., the inner surface of the rear end opening 42 of the outer cylinder 4). The inward protrusion 45 is composed of an annular protrusion or multiple dispersed protrusions. The inner diameter (minimum inner diameter) D of the inward protrusion 45 is formed to be smaller than the inner diameter C of the inner fitting portion 43. The corner of the front end of the inward protrusion 45 is formed at an acute angle or a right angle. The rear surface of the inward protrusion 45 has an inclined surface whose inner diameter gradually increases toward the rear.

The inner cylinder 5 is a bottomed cylinder having an open front end and a closed rear end, and is obtained by injection molding of a synthetic resin.

An annular outer fitting portion 51 is integrally formed on the outer surface of the inner cylinder 5 (the outer surface of the large outer diameter portion of the inner cylinder 5). The outer fitting portion 51 consists of an annular protrusion or multiple dispersed protrusions. The outer fitting portion 51 has an outer diameter slightly larger than the inner diameter C of the inner fitting portion 43. As shown in FIG. 6, when the inner fitting portion 43 consists of an annular protrusion, the inner cylinder 5 is fixed to the outer cylinder 4 by a jump fit. When the inner fitting portion 43 consists of an annular smooth surface, the inner cylinder 5 is fixed to the outer cylinder 4 by a press fit.

The outer surface of the inner cylinder 5 forward of the outer fitting portion 51 is provided with a flange portion 53 that protrudes radially outward. The flange portion 53 is made of an annular protrusion or multiple dispersed protrusions. The outer diameter of the flange portion 53 is set to be the same as the inner diameter B of the outer cylinder 4 or smaller than the inner diameter B. In this embodiment, the outer diameter of the flange portion 53 is set to be approximately the same as the inner diameter B, thereby improving the radial stability of the inner cylinder 5. Even if the outer diameter of the flange portion 53 is approximately the same as the inner diameter B, the inner fitting portion 43 is not damaged by the flange portion 53 because the inner fitting portion 43 is provided behind the regulating wall portion 44. The abutment wall portion 54 is integrally formed with the rear end of the flange portion 53. The abutment wall portion 54 is a surface perpendicular to the axis. The outer diameter of the rear end of the abutment wall portion 54 is set to be larger than the outer diameter of the outer fitting portion 51.

In FIG. 6, the axial distance from the outer fitting portion 51 to the flange portion 53 is set to be slightly larger than the axial distance from the inner fitting portion 43 to the regulating wall portion 44. With this configuration, when the inner cylinder 5 is inserted into the outer cylinder 4, the outer fitting portion 51 overcomes and fits over the inner fitting portion 43, and then the flange portion 53 and the regulating wall portion 44 come into contact, and the inner cylinder 5 is fixed at a predetermined position within the outer cylinder 4.

The inner surface of the front end of the inner cylinder 5 is formed with an annular seal portion 55 that fits airtightly with the outer surface of the writing instrument body 2. The annular seal portion 55 is made of an annular protrusion or an annular smooth surface. The annular seal portion 55 is configured to be deformable in the radial direction, so the outer fitting portion 51 and the flange portion 53 are provided behind the annular seal portion 55.

The outer diameter of the inner cylinder 5 rearward from the outer fitting portion 51 gradually decreases toward the rear. In this embodiment, the rear end of the inner cylinder 5 has a truncated cone shape. Since the outer diameter of the inner cylinder 5 decreases toward the rear, the insertability of the inner cylinder 5 into the outer cylinder 4 is improved.

The restricting wall portion 44 may be shaped so that the inner diameter gradually decreases toward the rear. As shown in FIG. 7, by making the restricting wall portion 44 tapered, the insertability of the inner cylinder body 5 into the outer cylinder body 4 is further improved. When the restricting wall portion 44 is tapered, the restricting wall portion 44 and the flange portion 53 abut in a line contact.

Friction body The friction body 6 is composed of a large diameter portion and a small diameter portion that is integrally connected to the front of the large diameter portion, and is integrally formed from an elastic material. The friction body 6 is formed from an elastic material such as synthetic rubber or elastomer. In this embodiment, a friction-discoloring member that rubs the surface of handwriting formed with thermochromic ink to thermally discolor the handwriting is used as the friction body 6. Other examples of the friction body 6 made of an elastic material include an eraser. The friction body 6 is inserted into the rear end opening of the outer cylinder body 4 from the rear toward the front.

The rear surface of the large diameter portion has a convex curved shape. A shoulder portion is formed at the front end of the large diameter portion so as to be able to abut against the open end of the rear end opening 42 of the outer cylinder 4 (specifically, the rear end of the outer cylinder 4). The maximum outer diameter of the large diameter portion is set to be larger than the inner diameter of the rear end opening 42 of the outer cylinder 4 and smaller than the outer diameter of the rear end of the outer cylinder 4.

An annular outward protrusion 61 is integrally formed on the outer circumferential surface of the front end of the small diameter portion. The front surface of the outward protrusion 61 has an inclined surface (i.e., a conical surface) whose outer diameter gradually increases toward the rear. The rear end of the outward protrusion 61 has a right-angled or acute-angled corner.

The outer diameter (maximum outer diameter) of the outward protrusion 61 is formed larger than the inner diameter D (minimum inner diameter) of the inward protrusion 45, so that the outward protrusion 61 and the inward protrusion 45 can be reliably locked and prevented from coming off. The outer diameter (maximum outer diameter) of the outward protrusion 61 is formed smaller than the inner diameter of the rear end opening 42 of the outer cylindrical body 4 behind the inward protrusion 45, so that the outward protrusion 61 and the inner surface of the rear end opening of the outer cylindrical body 4 behind the inward protrusion 45 are maintained in a non-engaged state, and the friction body 6 can be smoothly inserted until just before the outward protrusion 61 rides over the inward protrusion 45. When the friction body 6 is completely inserted into the rear end opening 42 of the outer cylindrical body 4 (when the over-engagement is completed), the outer surface of the friction body 6 behind the outward protrusion 61 and the inward protrusion 45 are engaged.

When the friction body 6 has been completely inserted into the rear end opening 42 of the outer tube body 4 (when the over-riding fit has been completed), the rear end of the outward projection 61 (i.e., the maximum outer diameter portion) is located forward of the front end of the inward projection 45 (i.e., the minimum inner diameter portion), and an axial gap is formed between the front end of the inward projection 45 and the rear end of the outward projection 61. As a result, when the outward projection 61 rides over the inward projection 45 from rear to front, the outward projection 61 can reliably ride over the inward projection 45 even if the sliding between the outward projection 61 and the inward projection 45 is poor.

In addition, when the friction body 6 is completely inserted into the rear end opening 42 of the outer cylindrical body 4 (when the over-riding fitting is complete), a radial gap is formed between the outer surface of the outward protrusion 61 and the inner surface of the outer cylindrical body 4. As a result, when the outward protrusion 61 rides over the inward protrusion 45 from rear to front, even if the outward protrusion 61 and the inward protrusion 45 do not slide easily, the outward protrusion 61 can reliably ride over the inward protrusion 45.

The thermochromic writing instrument 1 of this embodiment is a thermochromic writing instrument that includes a writing instrument body 2 having a pen tip 21 capable of discharging thermochromic ink, or a cap body 7 that can be attached to the pen tip 21 of the writing instrument body 2, and is attached to the writing instrument body 2 or the cap body 7 and has a friction body 6 that rubs the handwriting of the thermochromic ink. The writing instrument body 2 or the cap body 7 includes an outer tube 4 and an inner tube 5 that is fitted to the inner surface of the outer tube 4, a friction body 6 is attached to the rear end of the outer tube 4, and a friction body 6 is attached to the outer surface of the inner tube 5. The outer fitting portion 51 is formed, the inner surface of the outer cylinder 4 is formed with an inner fitting portion 43 that fits with the outer fitting portion 51, the outer surface of the inner cylinder 5 is formed with a rearward-facing abutment wall portion 54, and the inner surface of the outer cylinder 4 is integrally formed with a regulating wall portion 44 that abuts against the abutment wall portion 54 in the front-rear direction and prevents the inner cylinder 5 from moving rearward. The regulating wall portion 44 is provided forward of the inner fitting portion 43, so that when the inner cylinder 5 is inserted into the outer cylinder 4, the inner fitting portion 43 can be prevented from being scratched by the inner surface of the outer cylinder 4. In addition, since the regulating wall portion 44 forward of the inner fitting portion 43 restricts the movement of the inner cylinder 5, the outer diameter of the inner cylinder 5 rearward of the outer fitting portion 51 can be set arbitrarily, improving the insertability of the inner cylinder 5 into the outer cylinder 4.

The thermochromic writing instrument of this embodiment is a thermochromic writing instrument comprising a writing instrument body 2 having a pen tip 21 in which thermochromic ink is built and capable of ejecting the ink, a cap body 7 that can be attached to the pen tip 21 of the writing instrument body 2, and a friction body 6 that is attached to the cap body 7 and rubs the handwriting of the thermochromic ink, and the cap body 7 comprises an outer tube 4 and an inner tube 5 that is fitted to the inner surface of the outer tube 4, the friction body 6 is attached to the rear end of the outer tube 4, an outer fitting portion 51 is formed on the outer surface of the inner tube 5, an inner fitting portion 43 that fits with the outer fitting portion 51 is formed on the inner surface of the outer tube 4, and a friction body 6 is attached to the outer surface of the inner tube 5 at the rear. A contact wall 54 is formed facing the outer cylinder 4, and a restricting wall 44 is integrally formed on the inner surface of the outer cylinder 4 forward of the inner fitting 43, which contacts the contact wall 54 in the front-rear direction and prevents the inner cylinder 5 from moving rearward. An annular seal 55 is provided at the front end of the inner surface of the inner cylinder 5, which fits airtightly with the writing instrument body 2. The outer fitting 51 is provided rearward of the contact wall 54, and the contact wall 54 is provided rearward of the annular seal 55. This maintains the airtight performance of the cap body 7 as a cap, while preventing the inner cylinder 5 from getting caught on the inner surface of the outer cylinder 4 and damaging the inner fitting 43 when the inner cylinder 5 is inserted into the outer cylinder 4.

The thermochromic writing instrument 1 of this embodiment has a flange 53 that protrudes radially outward on the outer surface of the inner cylinder 5 forward of the outer fitting 51, and an abutment wall 54 is provided at the rear end of the flange 53, which prevents the flange 53, which has a larger outer diameter, from getting caught and scratching the inner fitting 43 when the inner cylinder 5 is inserted into the outer cylinder 4. In addition, because the flange 53, which has a larger outer diameter, is provided forward of the outer fitting 51, the insertability of the inner cylinder 5 into the outer cylinder 4 is improved.

Reference Signs List 1 Writing implement 2 Writing implement body 21 Pen tip 22 Ink occlusion body 3 Pen tip holding tube 4 Outer tube body 41 Front end opening 42 Rear end opening 43 Inner fitting portion 44 Regulating wall portion 45 Inward projection 5 Inner tube body 51 Outer fitting portion 52 Notch 53 Flange portion 54 Abutment wall portion 55 Annular seal portion 6 Friction body 61 Outward projection 7 Cap body B Inner diameter of outer tube body C Inner diameter of inner fitting portion D Inner diameter of inward projection

Claims (4)

A thermochromic writing instrument comprising a writing instrument body having a thermochromic ink built therein and a pen tip capable of ejecting the ink, or a cap body that can be attached to the pen tip of the writing instrument body, and a friction body that is attached to the writing instrument body or the cap body and rubs the handwriting of the thermochromic ink,
The writing instrument body or the cap body includes an outer cylinder body and an inner cylinder body fitted to the inner surface of the outer cylinder body,
The friction body is attached to the rear end of the outer cylinder,
An outer fitting portion is formed on the outer surface of the inner cylinder, and an inner fitting portion that fits with the outer fitting portion is formed on the inner surface of the outer cylinder,
A thermochromic writing instrument characterized in that a rear-facing abutment wall portion is formed on the outer surface of the inner cylinder, and a regulating wall portion is integrally formed on the inner surface of the outer cylinder that abuts against the abutment wall portion in the front-to-rear direction and prevents the inner cylinder from moving rearward, and the regulating wall portion is located forward of the inner fitting portion. A thermochromic writing instrument comprising a writing instrument body having a thermochromic ink built therein and a pen tip capable of ejecting the ink, or a cap body that can be attached to the pen tip of the writing instrument body, and a friction body that is attached to the writing instrument body or the cap body and rubs the handwriting of the thermochromic ink,
The writing instrument body or the cap body includes an outer cylinder body and an inner cylinder body fitted to the inner surface of the outer cylinder body,
the outer cylinder body has an inner hole penetrating in the front-rear direction, and a front end opening and a rear end opening communicating with the inner hole,
The friction body is attached to the rear end opening of the outer cylinder body,
An outer fitting portion is formed on an outer surface of the inner cylinder, and an inner fitting portion that fits airtightly with the outer fitting portion is formed on an inner surface of the outer cylinder,
A thermochromic writing instrument characterized in that a rear-facing abutment wall portion is formed on the outer surface of the inner cylinder, and a regulating wall portion is integrally formed on the inner surface of the outer cylinder that abuts against the abutment wall portion in the front-to-rear direction and prevents the inner cylinder from moving rearward, and the regulating wall portion is located forward of the inner fitting portion. A thermochromic writing instrument comprising: a writing instrument body having a thermochromic ink built therein and a pen tip capable of discharging the ink; a cap body that can be attached to the pen tip of the writing instrument body; and a friction body that is attached to the cap body and rubs the writing of the thermochromic ink,
The cap body includes an outer cylinder and an inner cylinder fitted to the inner surface of the outer cylinder,
The friction body is attached to the rear end of the outer cylinder,
An outer fitting portion is formed on the outer surface of the inner cylinder, and an inner fitting portion that fits with the outer fitting portion is formed on the inner surface of the outer cylinder,
a rearward-facing abutment wall portion is formed on an outer surface of the inner cylinder body, and a restricting wall portion is integrally formed on an inner surface of the outer cylinder body forward of the inner fitting portion, the restricting wall portion abutting against the abutment wall portion in the front-rear direction and preventing the inner cylinder body from moving rearward;
An annular seal portion is provided at the front end of the inner surface of the inner cylinder and is airtightly fitted with the writing instrument body,
A thermochromic writing implement, characterized in that the outer fitting portion is provided rearward of the abutment wall portion, and the abutment wall portion is provided rearward of the annular seal portion. A thermochromic writing instrument according to any one of claims 1 to 3, characterized in that a flange protruding radially outward is provided on the outer surface of the inner cylinder forward of the outer fitting portion, and the abutment wall is provided at the rear end of the flange.

Images