Friction body unit and heat color-changing writing instrument

Abstract

The rubbing body unit (3) of the present application is provided with a rubbing body (5) configured to generate rubbing heat for thermally changing the handwriting of a thermochromic ink, and a holding portion (4) holding the rubbing body (5) and configured to be attached to and detached from a pen barrel (2) or a pen cap of a thermochromic writing instrument, wherein the holding portion (4) has a cylindrical side wall forming an internal space (41) that is open at least downward, at least one air hole (44) is formed in the side wall to communicate with the internal space (41), and air can flow between the air hole (44), the internal space (41), and the opening downward.

Description

Technical Field

[0001] The present invention relates to a friction element unit configured to be detachable from a thermochromic writing instrument, and a thermochromic writing instrument having the friction element unit. Background Technology

[0002] The thermochromic writing instrument comprises thermochromic ink and a friction element. The friction element is made of an elastic material. Frictional heat is generated by rubbing the thermochromic ink on the paper surface with the friction element. This frictional heat causes the ink to change color. The friction element wears down with repeated use. Therefore, the applicant proposes a friction element unit that can be attached to and detached from the thermochromic writing instrument. With the friction element unit, the worn friction element can be easily replaced with a new one.

[0003] For example, in Japanese Patent Application Publication No. 2013-188922 Figure 6 The present applicant discloses a conventional friction element unit. The friction element unit includes a holding portion 4 and a friction element 5. Three grooves 4CA extending in a vertical direction are formed on the sidewall 4C of the holding portion 4. The lower end of each groove 4CA is continuous with a through hole 4CB. The through hole 4CB extends vertically through the lower end portion 4D of the sidewall 4C. Even in the event of accidental swallowing of the friction element unit by a child, air can circulate through the grooves 4CA and the through hole 4CB.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-188922 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In recent years, in order to improve consumers' quality of life, writing instruments have tended to be designed to be more aesthetically pleasing. Today, new products designed in a wide variety of styles are constantly being introduced to the market. On the other hand, all components of a writing instrument have structures for achieving a certain function. Ideally, the structure used to achieve this function should not restrict the design freedom of the writing instrument.

[0009] However, in the aforementioned conventional friction element unit, there is a problem where the design freedom of the retaining part 4 is limited by the multiple through holes 4CB used to allow air flow. That is, the multiple through holes 4CB form a structure that extends vertically through the lower end 4D of the sidewall 4C of the retaining part 4. To provide multiple through holes 4CB, the outer diameter of the lower end 4D of the sidewall 4C must be increased, thus restricting the design freedom of the retaining part 4. This restriction on the design freedom of the retaining part 4 means that the design freedom of the friction element unit and the thermochromic writing instrument is also restricted.

[0010] The present invention was made in view of the above-mentioned problems, and its object is to provide a friction element unit and a thermochromic writing instrument having the friction element unit, wherein the friction element unit can improve the design freedom by having a structure that allows sufficient airflow without increasing the outer diameter of the side wall of the holding part.

[0011] Methods for solving problems

[0012] (1) In order to achieve the above objective, the friction body unit of the present invention includes a friction body and a holding part. The friction body is configured to generate frictional heat for causing the handwriting of thermochromic ink to change color. The holding part holds the friction body and is configured to be detachable from the barrel or cap of the thermochromic writing instrument. The friction body unit is characterized in that the holding part has a cylindrical sidewall forming an internal space with an opening at least downward. At least one vent hole is formed on the sidewall communicating with the internal space, and air can flow between the vent hole, the internal space and the opening downward.

[0013] In the friction element unit described in (1) above, an airflow path communicating with the inside and outside of the holding part is formed by the vent, the internal space, and the opening below the internal space. This airflow path ensures a child's airway even if the friction element unit is accidentally swallowed. In particular, by using the internal space and the opening below as the airflow path, sufficient airflow is achieved. This airflow path is formed from the outer surface of the side wall of the holding part to the inner surface, thus not restricting the design freedom of the holding part. Therefore, according to the present invention, the design freedom of the friction element unit and the thermochromic writing instrument is increased.

[0014] (2) Preferably, in the friction body unit of (1) above, the cylindrical sidewall of the retaining part includes a portion with a large outer diameter and a portion with a small outer diameter, and the vent has a first opening formed on the outer surface of the sidewall and a second opening formed on the inner surface of the sidewall, at least the first opening is located above the maximum outer diameter portion of the sidewall.

[0015] In the friction element unit described in (2) above, the first opening of the vent is located in the portion of the cylindrical sidewall of the retaining part whose outer diameter is smaller than the maximum outer diameter portion. Therefore, in the event that a child accidentally swallows the friction element unit, the maximum outer diameter portion of the sidewall of the retaining part contacts the child's tracheal wall, while the portion with an outer diameter smaller than the maximum outer diameter portion does not contact the child's tracheal wall. As a result, the first opening of the vent will not be blocked by the child's tracheal wall, ensuring the child's airway for breathing.

[0016] Furthermore, in this invention, the term "outer diameter" refers to the diameter of the horizontal cross-section of the sidewall when the sidewall of the retaining part is cylindrical, and the diameter of the circle circumscribed in the horizontal cross-section of the sidewall when the sidewall of the retaining part is cylindrical or otherwise cylindrical. Additionally, the term "maximum outer diameter portion" in this invention assumes that the sidewall of the retaining part is cylindrical or otherwise cylindrical, and refers to the portion where the diameter of the circle circumscribed in the horizontal cross-section of the sidewall is the largest.

[0017] (3) Preferably, in the friction body unit of (2) above, at least a portion of the cylindrical sidewall of the holding part is provided with a tapered portion whose outer diameter decreases from bottom to top, and the first opening of the vent hole is formed in the tapered portion.

[0018] In the friction element unit described above (3), a first opening for a vent is formed in the tapered portion whose outer diameter decreases from bottom to top. Therefore, in the event that a child accidentally swallows the friction element unit, the portion with the largest outer diameter of the retaining part's sidewall contacts the child's tracheal wall, while the portion with an outer diameter smaller than the largest outer diameter does not contact the child's tracheal wall. As a result, the first opening for the vent is not blocked by the child's tracheal wall, ensuring the child's airway for breathing.

[0019] (4) Preferably, in the friction body unit of (3) above, the cylindrical sidewall of the retaining part includes a first tapered part located above the maximum outer diameter part and a second tapered part located above the first tapered part. The outer diameter of the first tapered part decreases upward from the upper end of the maximum outer diameter part, and the outer diameter of the second tapered part decreases upward from the upper end of the first tapered part. The inclination angle of the second tapered part is larger than the inclination angle of the first tapered part, and the first opening of the vent is formed in the second tapered part.

[0020] The sidewall of the retaining portion of the friction element unit described above (4) includes a maximum outer diameter portion, a first conical portion, and a second conical portion. The second conical portion has an outer diameter smaller than that of the first conical portion and an inclination angle larger than that of the first conical portion. The first opening of the vent is formed in the second conical portion. Thus, in the event that a child accidentally swallows the friction element unit, even if the friction element unit is tilted and causes the first conical portion to come into contact with the child's tracheal wall, the second conical portion will not come into contact with the child's tracheal wall. As a result, the first opening of the vent will not be blocked by the child's tracheal wall, ensuring the child's airway for breathing.

[0021] (5) Preferably, in the friction body unit of (3) above, the outer diameter of the portion of the cylindrical sidewall of the retaining part that is above the upper end of the second opening of the vent hole is less than the outer diameter of the upper end of the second opening.

[0022] The outer diameter of the portion of the sidewall of the retaining part of the friction element unit described above (5), which is above the upper end of the second opening of the vent, is less than or equal to the outer diameter of the upper end of the second opening. Therefore, in the event of a child accidentally swallowing the friction element unit, the portion above the upper end of the second opening of the vent will not come into contact with the child's tracheal wall. As a result, a larger gap is formed between the portion above the upper end of the second opening of the vent and the child's tracheal wall, ensuring the child's airway for breathing. Furthermore, since the outer diameter of the portion above the upper end of the second opening of the vent is less than or equal to the outer diameter of the upper end of the second opening, the shape of the retaining part can be injection molded using a single, undivided mold, eliminating the need for a sliding core to form the vent. As a result, the cost of injection molding the retaining part can be reduced.

[0023] (6) Preferably, in any of the above (2) to (5), an annular outward protrusion is provided on the outer surface of the lower side of the friction body, and an annular inward protrusion is provided on the inner surface of the cylindrical sidewall of the retaining part. The sidewall opens downward and upward, and at least the second opening of the vent is located below the inward protrusion. When the lower side of the friction body is inserted into the internal space from the opening above the sidewall, the outward protrusion is locked with the inward protrusion. When the outward protrusion is locked with the inward protrusion, a gap is formed between the outer surface of the outward protrusion and the inner surface of the sidewall, and the gap communicates with the vent.

[0024] In the friction element unit described above (6), the annular outward protrusion and the inward protrusion are locked together within a 360-degree range, thereby firmly holding the lower side of the friction element within the internal space of the retaining part. Furthermore, with the outward and inward protrusions locked together, a gap is formed between the outer surface of the outward protrusion and the inner surface of the sidewall. This gap communicates with the vent hole, maintaining an airflow path that connects the inside and outside of the retaining part.

[0025] (7) Preferably, in any of the above (1) to (6) friction body units, a plurality of recesses are formed along the lower end of the cylindrical sidewall of the retaining portion.

[0026] In the friction element unit described above (7), a plurality of recesses are formed along the lower end of the cylindrical sidewall of the retaining part. First, the plurality of recesses are used to maintain the posture of the retaining part during the automated assembly process of the friction element unit. That is, the plurality of recesses are engaged with the plurality of protrusions formed in the clamp. As a result, the movement and rotation of the retaining part are restricted, and the friction element can be easily assembled into the retaining part.

[0027] Second, multiple recesses prevent the retaining part from being securely attached to the barrel or cap of the thermochromic writing instrument. That is, the friction element unit is installed on the barrel or cap of the thermochromic writing instrument. In this case, the lower end of the side wall of the retaining part is in contact with the surface of the barrel or cap. Under conditions of high surface contact pressure and a large contact area, the lower end of the side wall of the retaining part is securely attached to the barrel or cap, sometimes making it impossible to remove the friction element unit by hand. Multiple recesses reduce the area of ​​the lower end of the side wall of the retaining part, making it easier to remove the friction element unit by hand.

[0028] Furthermore, multiple recesses receive foreign objects such as dust or dirt between the lower end of the sidewall of the retaining part and the pen barrel or cap, ensuring that foreign objects do not obstruct the installation of the friction element unit. Alternatively, multiple protrusions can be formed on the pen barrel or cap of the thermochromic writing instrument. When the friction element unit is installed on the pen barrel or cap of the thermochromic writing instrument, the multiple recesses engage with the multiple protrusions, restricting the rotation of the retaining part. When a structure is used to screw the friction element unit onto the pen barrel or cap, the friction element unit will not accidentally detach from the pen barrel or cap.

[0029] (8) In order to achieve the above objective, the thermochromic writing instrument of the present invention includes a friction body unit of any one of (1) to (7) above, characterized in that a first connecting part is provided in the pen barrel or pen cap of the thermochromic writing instrument, and a second connecting part is provided in the friction body unit to be detachable relative to the first connecting part.

[0030] The thermochromic writing instrument described in (8) above allows for flexible design of the friction element unit based on the design of the pen barrel or cap. For example, by making the outer diameter of the retaining part of the friction element unit match the outer diameter of the pen barrel or cap, the appearance of the friction element unit can be integrated with the appearance of the pen barrel or cap. In particular, in the friction element units described in (1) to (7) above, there is no limitation that the outer diameter of the retaining part must be increased to ensure airflow. Therefore, when the outer diameter of the pen barrel or cap is small, the outer diameter of the retaining part can be reduced. With the friction element unit, the overall design of the thermochromic writing instrument can be made to have a slender appearance.

[0031] (9) In order to achieve the above objective, the thermochromic writing instrument of the present invention includes the friction body unit of (6) above, characterized in that a first connecting part is provided in the pen barrel or pen cap of the thermochromic writing instrument, and a second connecting part is provided in the friction body unit to be detached from the first connecting part, wherein when the second connecting part is engaged with the first connecting part, the first connecting part is located in the gap formed between the outer surface of the outwardly protruding part and the inner surface of the sidewall.

[0032] In the thermochromic writing instrument described in (9) above, the gap formed in the internal space of the friction element unit described in (6) above can be effectively utilized. That is, a gap constituting a portion of the air passage is formed in the internal space of the holding part of the friction element unit described in (6) above. Here, the air passage of the friction element unit functions in the event that a child accidentally swallows the friction element unit removed from the thermochromic writing instrument. On the other hand, when the friction element unit is installed in the thermochromic writing instrument, the air passage of the friction element unit does not function. Therefore, in the thermochromic writing instrument described in (9) above, by providing a structure in which the first connecting part of the thermochromic writing instrument is housed in the gap constituting a portion of the air passage of the friction element unit, this gap can be effectively utilized.

[0033] The effects of the invention

[0034] The friction element unit of the present invention allows for sufficient airflow without increasing the outer diameter of the sidewall of the retaining part, thus increasing design freedom. Furthermore, the thermochromic writing instrument of the present invention allows for a unified appearance design of the entire thermochromic writing instrument, including the friction element unit. In particular, it allows for a slender overall design of the thermochromic writing instrument. Attached Figure Description

[0035] Figure 1 This is a front view of a thermochromic writing instrument equipped with the friction element unit of the first embodiment of the present invention.

[0036] Figure 2 It means including Figure 1A cross-sectional view of the friction element and the pen barrel.

[0037] Figure 3 It means to Figure 2 A cross-sectional view of the friction element unit and the pen barrel after disassembly.

[0038] Figure 4 This is the front view representing the friction element.

[0039] Figure 5 This is the right view of the friction element.

[0040] Figure 6 This is a three-dimensional diagram representing a friction element unit.

[0041] Figure 7 This is a three-dimensional view showing the vent holes of the friction element unit.

[0042] Figure 8 This is a top view representing a friction element.

[0043] Figure 9 yes Figure 4 BB cross-sectional view.

[0044] Figure 10 This is a front view of a thermochromic writing instrument equipped with the friction element unit of the second embodiment of the present invention.

[0045] Figure 11 It means including Figure 10 A cross-sectional view of the friction element and the pen barrel.

[0046] Figure 12 It means to Figure 11 A cross-sectional view of the friction element unit and the pen barrel after disassembly.

[0047] Figure 13 This is a front view of a thermochromic writing instrument equipped with the friction element unit of the third embodiment of the present invention.

[0048] Figure 14 It means including Figure 13 A cross-sectional view of the friction element and the pen barrel.

[0049] Figure 15 It means to Figure 14 A cross-sectional view of the friction element unit and the pen barrel after disassembly.

[0050] Figure 16 This is the front view representing the friction element.

[0051] Figure 17 This is the left view representing the friction element.

[0052] Figure 18 This is a three-dimensional view of a friction element unit.

[0053] Figure 19 This is a three-dimensional view showing the vent holes of the friction element unit.

[0054] Figure 20 This is a top view representing a friction element.

[0055] Figure 21 yes Figure 16 BB cross-sectional view.

[0056] Figure 22 This is a perspective view of the friction body unit according to the fourth embodiment of the present invention. Detailed Implementation

[0057] Hereinafter, embodiments of the friction element unit and the thermochromic writing instrument of the present invention will be described with reference to the accompanying drawings. Furthermore, in the following description, Figure 1 , Figure 10 as well as Figure 13 The direction of the tip of the thermochromic writing instrument 1 is defined as "down", and the direction of the friction body 5 is defined as "up".

[0058] <First Implementation Method>

[0059] First, refer to Figures 1 to 9 The friction element unit and the thermochromic writing instrument of the first embodiment of the present invention will be described.

[0060] like Figure 1 As shown, the thermochromic writing instrument 1 of the first embodiment is, for example, a retractable thermochromic writing instrument. Inside the pen barrel 2, a refill (not shown) is housed, movable in the vertical direction. Thermochromic ink is housed inside the refill. A pen tip, capable of dispensing thermochromic ink, is provided at the front end of the refill. The thermochromic writing instrument 1 has a pen tip retraction mechanism. By sliding the pen clip 2d downwards, the pen tip protrudes from the lower end of the pen barrel 2, or the pen tip retracts into the pen barrel 2. Figure 1 This indicates the state where the pen tip is retracted into the pen barrel 2. In this retracted state, by sliding the pen clip 2d downwards, the pen tip protrudes from the lower end of the pen barrel 2. In this protruding state, by sliding the pen clip 2d downwards, the pen tip retracts into the pen barrel 2.

[0061] On the other hand, a friction element unit 3 is installed at the upper end of the pen barrel 2. The friction element unit 3 consists of a holding part 4 and a friction element 5. Frictional heat is generated by rubbing the thermochromic ink writing on the paper surface with the friction element 5. Through this frictional heat, the thermochromic ink writing can be thermochromized.

[0062] Furthermore, the form of the thermochromic writing instrument of the present invention is not limited to a telescopic type. For example, the thermochromic writing instrument of the present invention can also be a cap-type thermochromic writing instrument with a structure in which a cap covers a pen tip protruding from the lower end of the pen barrel. In this case, the friction element unit 3 is mounted on the end of the cap or the upper end of the pen barrel. Here, the end of the cap refers to the end opposite to the opening into which the lower end of the pen barrel is inserted. The pen barrel and cap of the cap-type thermochromic writing instrument are made of synthetic resin or metal.

[0063] ・Replacement core

[0064] The refill is a structure that presses the pen tip into the opening at the lower end of the ink reservoir. The ink reservoir is filled with thermochromic ink and a follower. The follower is located at the upper end of the thermochromic ink inside the ink reservoir and descends as the thermochromic ink is consumed. The follower is, for example, made of a high-viscosity fluid. Additionally, a stopcock is installed at the opening at the upper end of the ink reservoir. A through-hole is provided on the stopcock to allow air to flow between the inside and outside of the ink reservoir.

[0065] Thermochromic ink

[0066] Thermochromic inks have the property of changing color when heated or cooled. Thermochromic inks can change color from colored to colorless, from colorless to colored, or from a first colored color to a second colored color.

[0067] Thermochromic inks are preferably reversible thermochromic inks that can restore the state before and after the thermochromic change. Reversible thermochromic inks include types such as heat-activated decolorizing inks, color-memory retaining inks, and heat-developing inks. Heat-activated thermochromic inks change from colored to colorless upon heating. Color-memory retaining inks reversibly change to a colored or colorless state within a specified temperature range and maintain the changed state within that range. Heat-developing inks change from colorless to colored upon heating and revert to colorless upon cooling. For example, in the case of a single-refill thermochromic writing instrument, either type of thermochromic ink can be used alone. Conversely, in the case of a multi-refill thermochromic writing instrument, two or more types of thermochromic inks can be used simultaneously.

[0068] As a pigment contained in reversible thermochromic inks, reversible thermochromic pigments containing a reversible thermochromic composition encapsulated in microcapsules are preferred. The reversible thermochromic composition comprises at least an electron-donating chromogenic organic compound, an electron-accepting compound, and a reaction medium. The temperature at which the chromogenic reaction occurs between the electron-donating chromogenic organic compound and the electron-accepting compound is determined by the reaction medium.

[0069] ·nib

[0070] The pen tip is, for example, made of metal. An opening for thermochromic ink is provided at the lower end of the pen tip. A ball bearing is rotatably held on the inner surface of the edge of this opening. The pen tip is pressed into the lower opening of the ink reservoir of the refill. Alternatively, the pen tip is pressed into the lower opening of the ink reservoir via a synthetic resin tip holder. The tip holder holds the upper outer surface of the pen tip. A coil spring is housed inside the pen tip to press the ball bearing towards the lower end of the tip. A rod is provided at the lower end of the coil spring. The lower end of this rod contacts the ball bearing. Through the force of the coil spring, the ball bearing is tightly sealed against the opening at the lower end of the pen tip. This prevents ink leakage and evaporation when not writing.

[0071] ·pen

[0072] like Figure 1 As shown, the pen barrel 2 of the thermochromic writing instrument 1 is composed of a lower shaft 2a, a middle shaft 2b, and an upper shaft 2c. The lower shaft 2a is mostly composed of a cylindrical portion. A tapered portion with a decreasing outer diameter from top to bottom is provided at the lower end of the cylindrical portion. The cylindrical portion of the lower shaft 2a serves as the grip of the thermochromic writing instrument 1. An opening is provided at the front end of the tapered portion of the lower shaft 2a. The pen tip of the refill extends and retracts from the opening at the front end of the tapered portion. The middle shaft 2b is composed only of a longer cylindrical portion. The lower end of the middle shaft 2b is connected to the upper end of the lower shaft 2a by screwing or pressing. The upper shaft 2c is composed only of a shorter cylindrical portion. The lower end of the upper shaft 2c is connected to the upper end of the middle shaft 2b by screwing or pressing. The lower shaft 2a, middle shaft 2b, and upper shaft 2c are formed, for example, of synthetic resins such as polycarbonate or metal.

[0073] like Figure 2 as well as Figure 3 As shown, a generally cylindrical first connecting portion 21 protruding upwards is provided at the upper end of the upper shaft 2c. An external thread 22 is provided on the outer surface of the first connecting portion 21. The second connecting portion 42, which is provided in the holding portion 4 of the friction body unit 3 described later, is screwed into the first connecting portion 21. In addition, the connection between the first connecting portion 21 and the second connecting portion 42 is not limited to screwing; for example, it can be changed to a fitting, pressing, or snap-fit ​​connection structure.

[0074] Here, the outer diameter of the first joint 21 is smaller than the outer diameter of the upper end of the upper shaft 2c. As a result, an annular step portion 23 is formed at the upper end of the upper shaft 2c. The lower end of the holding portion 4 of the friction body unit 3, described later, contacts the surface of this annular step portion 23.

[0075] • Friction body unit

[0076] Figures 2 to 9 This refers to friction element unit 3 in the first embodiment. For example... Figure 3 As shown, the friction unit 3 consists of a retaining part 4 and a friction body 5. The friction unit 3 is mounted on the upper shaft 2c of the pen barrel 2. The height of the friction unit 3 is, for example, 14.0 mm.

[0077] • Maintenance Department

[0078] like Figures 3 to 8 As shown, a friction element 5 is mounted on the upper part 47 of the retaining part 4. The retaining part 4 is formed, for example, from a synthetic resin such as polycarbonate or from metal. The height of the retaining part 4 is, for example, 8.0 mm.

[0079] like Figure 3 As shown, the retaining part 4 has a cylindrical sidewall forming an internal space 41 that opens upwards and downwards. A second connecting part 42 is provided on the lower side of the retaining part 4. An internal thread 43 is provided on the inner surface of the second connecting part 42. This internal thread 43 engages with the external thread 22 of the first connecting part 21 of the pen barrel 2. In addition, the engagement between the first connecting part 21 and the second connecting part 42 is not limited to screwing; for example, it can be changed to a fitting, pressing, or snap-fit ​​engagement structure.

[0080] The friction body 5 is mounted on the upper part 47 of the retaining part 4. An annular inward protrusion 45 is provided on the inner surface of the upper part 47. On the other hand, an annular outward protrusion 54 is provided on the lower outer surface of the friction body 5. When the lower side of the friction body 5 is inserted into the upper part 47 of the retaining part 4, the inward protrusion 45 and the outward protrusion 54 are engaged. In addition, the connection between the retaining part 4 and the friction body 5 is not limited to the engagement of the inward protrusion 45 and the outward protrusion 54, and can also be fitting, pressing, locking, screwing, bonding, or two-color molding, etc.

[0081] The annular inward protrusion 45 has a tapered inclined surface with an inner diameter that decreases from top to bottom and an annular lower surface. The inclined surface of the inward protrusion 45 is guided downward toward the lower side of the friction body 5, which is inserted into the upper part 47 of the retaining part 4, toward the inner space 41. As a result, the outward protrusion 54 can be smoothly locked into the inward protrusion 45, making the assembly of the friction body unit 3 easier.

[0082] like Figure 3 , Figure 4 as well as Figure 8 As shown, two vent holes 44 are formed in the retaining part 4. The two vent holes 44 are symmetrically arranged on the cylindrical sidewall of the retaining part 4 and communicate with the internal space 41 of the retaining part 4. The vent holes 44 function as airflow paths for the child's breathing in the event that the child accidentally swallows the friction element unit 3. In addition, the first opening 44a of the vent hole 44 formed on the outer surface of the retaining part 4 (see reference) Figure 7 It functions as an anti-slip part for the fingers holding the friction unit 3. As a result, it is easy to attach and detach the friction unit 3 from the pen barrel 2.

[0083] And, as Figure 5 As shown, three tapered portions 4b, 4c, and 4d with different inclination angles α, β, and γ are provided on the outer surface of the retaining portion 4. By ensuring that the inclination angles α, β, and γ of the three tapered portions 4b, 4c, and 4d are all less than 45°, it is easy to grip with fingers from any position on the side wall of the retaining portion 4. This facilitates the attachment and detachment of the friction element unit 3 from the pen barrel 2. Furthermore, anti-slip features such as grooves or knurling can be formed on the outer surface of the side wall of the retaining portion 4, excluding the vent hole 44.

[0084] like Figure 3 as well as Figure 7 As shown, the vent 44 has a first opening 44a formed on the outer surface of the sidewall of the retaining portion 4 and a second opening 44b formed on the inner surface of the sidewall of the retaining portion 4. The vent 44 is positioned higher than the second connecting portion 42, and the second opening 44b of the vent 44 is positioned lower than the inward protrusion 45. With this structure, the vent 44 penetrates the sidewall of the retaining portion 4 without interfering with the second connecting portion 42 and the inward protrusion 45. That is, the functions of the second connecting portion 42 and the inward protrusion 45 are not obstructed by the vent 44 penetrating the sidewall of the retaining portion 4. As a result, the second connecting portion 42 can be reliably screwed into the first connecting portion 21, and the inward protrusion 45 can be reliably engaged with the outward protrusion 54.

[0085] like Figures 5 to 7 As shown, the first opening 44a of the vent 44 is formed on the inclined surface of the second conical portion 4c, where the outer diameter decreases from bottom to top. Therefore, a [missing information - likely a typo, should be inserted here] is generated between the upper and lower ends of the first opening 44a of the vent 44. Figure 4 The diameter difference A is shown. This diameter difference A allows the interior of the vent 44 to expand from the second opening 44b to the first opening 44a. Therefore, even if a child accidentally swallows the friction element unit 3, a sufficient amount of air can be obtained from the vent 44. Figure 4 The diameter difference A shown is preferably 0.5 mm or more.

[0086] like Figure 5 as well as Figure 6 As shown, the outer surface of the retaining part 4 is composed of a maximum outer diameter part 4a, a first tapered part 4b, a second tapered part 4c, a third tapered part 4d, and a chamfered part 4e. The first tapered part 4b is located above the maximum outer diameter part 4a. The second tapered part 4c is located above the first tapered part 4b. The third tapered part 4d is located above the second tapered part 4c. The chamfered part 4e is located above the third tapered part 4d. Alternatively, the outer surface of the maximum outer diameter part 4a can be removed, and the lower end of the first tapered part 4b can be used as the maximum outer diameter part 4a.

[0087] The outer diameters of the first tapered portion 4b, the second tapered portion 4c, and the third tapered portion 4d all decrease from bottom to top. The outer diameter of the lowermost of the three tapered portions 4b, 4c, and 4d is preferably reduced by 10% to 30%. For example, the outer diameter of the lower end of the first tapered portion 4b (which is the same as the upper end of the portion with the largest outer diameter 4a) is 10.0 mm, and the outer diameter of the upper end of the first tapered portion 4b is 8.6 mm.

[0088] The lower end of the second conical portion 4c has an outer diameter of 8.6 mm, and the upper end has an outer diameter of 7.0 mm. The inclination angle β of the second conical portion 4c is larger than the inclination angle α of the first conical portion 4b (α < β). For easy handling of the holding portion 4, it is preferable that the inclination angle γ of the third conical portion 4d is smaller than the inclination angle β of the second conical portion 4c (γ < β). A vent 44 is formed in the second conical portion 4c. For example, it is set to α = 23°, β = 43°, and γ = 20°. Alternatively, the first conical portion 4b, the second conical portion 4c, and the third conical portion 4d can also be cones with very small inclination angles, such as the draft angle for easy removal of the molded part from the mold. In addition, the ends that form the boundaries of the three conical portions 4b, 4c, and 4d can also be chamfered.

[0089] exist Figure 9 The diagram shows the central angles θ1 and θ2 of the first opening 44a of the two vent holes 44. The central angles θ1 and θ2 of the first opening 44a are the angles formed by two imaginary lines connecting the two outermost ends of the first opening 44a to the center point of the retaining part 4. The sum θ (θ = θ1 + θ2) of the central angles θ1 and θ2 of the first opening 44a is preferably in the range of 90° to 180°, more preferably in the range of 90° to 150°. This is because if the sum θ is less than 90°, sufficient ventilation cannot be obtained, and if the sum θ exceeds 180° (more preferably 150°), sufficient strength of the retaining part 4 cannot be obtained.

[0090] exist Figure 5 The height C of the second opening 44b of the vent 44 is shown. The height C of the second opening 44b is preferably 0.5 mm or more. This is because if the height C of the second opening 44b is 0.5 mm or more, sufficient ventilation can be obtained in the event that a child accidentally swallows the friction element unit 3.

[0091] Friction body

[0092] like Figure 3As shown, the friction body 5 is a structure that integrally forms a projectile-shaped friction part 51 and a generally cylindrical mounting part 52. An axially extending inner hole is formed at the center of the friction body 5. Therefore, the interior of the friction body 5, except for the upper end of the friction part 51, is a cavity. The outer surface of the upper end of the friction part 51 is a convex curved surface. The horizontal cross-section of the friction part 51 is circular. The outer diameter of the friction part 51 is larger than the outer diameter of the mounting part 52. Therefore, an annular stepped portion 53 is formed at the boundary between the friction part 51 and the mounting part 52.

[0093] The aforementioned annular outward protrusion 54 is integrally formed on the outer surface of the mounting portion 52 of the friction body 5. The outward protrusion 54 has an annular upper surface and an inclined surface whose outer diameter decreases from top to bottom. When the mounting portion 52 of the friction body 5 is inserted into the upper portion 47 of the retaining portion 4, the inclined surface of the outward protrusion 54 is guided by the inclined surface of the aforementioned inward protrusion 45. As a result, the outward protrusion 54 smoothly passes through the inward protrusion 45 and is locked in place by the inward protrusion 45. At this time, the stepped portion 53 of the friction body 5 abuts against the upper end of the retaining portion 4.

[0094] By abutting the annular upper surface of the outward protrusion 54 against the annular lower surface of the inward protrusion 45, the friction body 5 will not easily detach from the upper part 47 of the retaining part 4. In addition, the engagement between the retaining part 4 and the friction body 5 is not limited to the locking of the inward protrusion 45 and the outward protrusion 54, but can also be a fitting, pressing, locking, screwing, bonding, or two-color molding, etc.

[0095] Furthermore, the outer diameter of the friction part 51 preferably decreases from bottom to top. Additionally, the maximum outer diameter of the friction part 51 is preferably smaller than the outer diameter of the upper end of the retaining part 4. By employing the structure described above, it is possible to prevent the friction element 5 from detaching from the retaining part 4, and in the event that a child accidentally swallows the friction element unit 3, it is possible to ensure airflow.

[0096] The friction element 5 is made of an elastic material. For example, synthetic resins with rubber-like elasticity, such as silicone resin, SBS resin (styrene-butadiene-styrene copolymer), and SEBS resin (styrene-ethylene-butene-styrene copolymer), are used. Frictional heat is generated by rubbing the thermochromic ink marks written on the paper surface with the friction element 51. This frictional heat causes the thermochromic ink marks to change color.

[0097] • Installation status of the friction element unit

[0098] like Figure 2 as well as Figure 3 As shown, the friction element unit 3 can be attached to and detached from the upper shaft 2c of the thermochromic writing instrument 1. Figure 2 As shown, when the friction body unit 3 is installed on the upper shaft 2c, the lower end of the retaining part 4 abuts against the stepped part 23 of the upper shaft 2c.

[0099] like Figure 3 As shown, an enlarged diameter portion 24, adapted to the shape of the outward protrusion 54, is provided above the inner surface of the first joint portion 21. The enlarged diameter portion 24 has an inclined surface whose inner diameter increases from bottom to top. Figure 2 As shown, when the friction body unit 3 is installed on the upper shaft 2c, the enlarged diameter portion 24 does not contact the outer surface of the outward protrusion 54.

[0100] Alternatively, the enlarged diameter portion 24 can also be structured to contact the outer surface of the outward protrusion 54. By having the outer surface of the outward protrusion 54 contact the enlarged diameter portion 24, the swaying of the friction body 5 can be suppressed.

[0101] In this first embodiment, the friction element unit 3 is configured such that when it is mounted on the upper shaft 2c, the upper end of the first coupling portion 21 is positioned above the lower end of the second opening 44b of the vent hole 44. This configuration allows for visual confirmation, via the vent hole 44, that the friction element unit 3 is fully mounted on the upper shaft 2c. Furthermore, it is preferable to use different colors for the retaining portion 4 and the first coupling portion 21. This makes it easy to determine whether the friction element unit 3 is fully mounted on the upper shaft 2c.

[0102] Furthermore, by positioning the upper end of the first joint 21 above the lower end of the second opening 44b of the vent 44, dust or dirt can be prevented from entering the interior of the friction body unit 3 through the vent 44, thus keeping the friction body unit 3 clean.

[0103] • Effects

[0104] In the friction element unit 3 of the first embodiment described above, an airflow path communicating with the inside and outside of the holding part 4 is formed by the vent 44, the internal space 41, and the opening below the internal space 41. This airflow path ensures a child's airway even if the friction element unit 3 is accidentally swallowed. In particular, by using the internal space 41 and the opening below as an airflow path, sufficient airflow can be achieved. This airflow path is formed from the outer surface of the side wall of the holding part 4 inwards, thus not restricting the design freedom of the holding part 4. Therefore, according to the structure of the first embodiment, the design freedom of the friction element unit 3 and the thermochromic writing instrument 1 is increased.

[0105] In the friction element unit 3 of the first embodiment, the first opening 44a of the vent 44 is located in the portion of the cylindrical sidewall of the retaining portion 4 whose outer diameter is smaller than the maximum outer diameter portion 4a. Therefore, in the event that a child accidentally swallows the friction element unit 3, the maximum outer diameter portion 4a of the sidewall of the retaining portion 4 contacts the child's tracheal wall, while the portion with an outer diameter smaller than the maximum outer diameter portion 4a does not contact the child's tracheal wall. As a result, the first opening 44a of the vent 44 will not be blocked by the child's tracheal wall, ensuring the child's airway for breathing.

[0106] In the friction element unit 3 of the first embodiment, a first opening 44a of a vent 44 is formed in the second tapered portion 4c, whose outer diameter decreases from bottom to top. Therefore, in the event that a child accidentally swallows the friction element unit 3, the maximum outer diameter portion 4a of the retaining portion 4 contacts the child's tracheal wall, while the portion with an outer diameter smaller than the maximum outer diameter portion 4a does not contact the child's tracheal wall. As a result, the first opening 44a of the vent 44 will not be blocked by the child's tracheal wall, ensuring the child's airway for breathing.

[0107] The sidewall of the holding portion 4 of the friction element unit 3 in the first embodiment includes a maximum outer diameter portion 4a, a first conical portion 4b, and a second conical portion 4c. The second conical portion 4c has an outer diameter smaller than that of the first conical portion 4b and an inclination angle β larger than that of the first conical portion 4b. The first opening 44a of the vent 44 is formed in the second conical portion 4c. Therefore, in the event that a child accidentally swallows the friction element unit 3, even if the friction element unit 3 is tilted and causes the first conical portion 4b to come into contact with the child's tracheal wall, the second conical portion 4c will not come into contact with the child's tracheal wall. As a result, the first opening 44a of the vent 44 will not be blocked by the child's tracheal wall, ensuring the child's airway for breathing.

[0108] In the thermochromic writing instrument 1 of the first embodiment, the annular outward protrusion 54 and the inward protrusion 45 are locked together within a 360-degree range, thereby firmly holding the mounting portion 52 of the friction body 5 within the internal space 41 of the holding portion 4. Furthermore, with the outward protrusion 54 and the inward protrusion 45 locked together, a gap is formed between the outer surface of the outward protrusion 54 and the inner surface of the holding portion 4. This gap communicates with the vent 44, maintaining an airflow path that connects the inside and outside of the holding portion 4.

[0109] Furthermore, the airflow path of the friction element unit 3 functions in the event that a child accidentally swallows the friction element unit 3 after it has been removed from the thermochromic writing instrument 1. On the other hand, when the friction element unit 3 is installed in the thermochromic writing instrument 1, the airflow path of the friction element unit 3 does not function. Therefore, in the first embodiment, the structure in which the first connecting portion 21 of the thermochromic writing instrument 1 is housed within the gap constituting a part of the airflow path of the friction element unit 3 effectively utilizes this gap.

[0110] <Second Implementation Method>

[0111] Next, refer to Figures 10 to 12 The friction element unit and the thermochromic writing instrument according to the second embodiment of the present invention will be described.

[0112] like Figure 11 as well as Figure 12As shown, the difference between the friction element unit 3 and the thermochromic writing instrument 1 of the second embodiment and the first embodiment is that an internal thread 22 is provided at the first joint portion 21 of the upper shaft 2c, and an external thread 43 is provided at the second joint portion 42 of the holding portion 4. In the following description of the friction element unit 3 and the thermochromic writing instrument 1 of the second embodiment, detailed descriptions of structures identical to those of the first embodiment are omitted.

[0113] ·pen

[0114] like Figure 10 As shown, the pen barrel 2 of the thermochromic writing instrument 1 is composed of a lower shaft 2a, a middle shaft 2b, and an upper shaft 2c. The lower shaft 2a is mostly composed of a cylindrical portion. A tapered portion with a decreasing outer diameter from top to bottom is provided at the lower end of the cylindrical portion. The cylindrical portion of the lower shaft 2a serves as the grip of the thermochromic writing instrument 1. An opening is provided at the front end of the tapered portion of the lower shaft 2a. The pen tip of the refill extends and retracts from the opening at the front end of the tapered portion. The middle shaft 2b is composed only of a longer cylindrical portion. The lower end of the middle shaft 2b is connected to the upper end of the lower shaft 2a by screwing or pressing. The upper shaft 2c is composed only of a shorter cylindrical portion. The lower end of the upper shaft 2c is connected to the upper end of the middle shaft 2b by screwing or pressing. The lower shaft 2a, middle shaft 2b, and upper shaft 2c are formed, for example, of synthetic resins such as polycarbonate or metal.

[0115] like Figure 11 as well as Figure 12 As shown, a first coupling portion 21 is provided at the upper end of the cylindrical upper shaft 2c. An internal thread 22 is provided on the inner surface of the first coupling portion 21. A second coupling portion 42 provided in the retaining portion 4 of the friction body unit 3 is screwed onto the first coupling portion 21. In addition, the coupling between the first coupling portion 21 and the second coupling portion 42 is not limited to screwing; for example, it can be changed to a fitting, pressing, or snap-fit ​​coupling structure.

[0116] • Friction body unit

[0117] like Figure 11 as well as Figure 12 As shown, the friction unit 3 consists of a retaining part 4 and a friction body 5. The friction unit 3 is mounted on the upper shaft 2c of the pen barrel 2. The height of the friction unit 3 is, for example, 14.0 mm.

[0118] • Maintenance Department

[0119] A friction element 5 is mounted on the upper part 47 of the retaining part 4. The retaining part 4 is formed, for example, from a synthetic resin such as polycarbonate or from metal. The height of the retaining part 4 is, for example, 8.0 mm.

[0120] like Figure 12As shown, the retaining part 4 has a cylindrical sidewall forming an internal space 41 that opens upwards and downwards. A generally cylindrical second connecting part 42 protruding downwards is provided on the lower side of the retaining part 4. An external thread 43 is provided on the outer surface of the second connecting part 42. This external thread 43 engages with the internal thread 22 of the first connecting part 21 of the pen barrel 2. Furthermore, the engagement between the first connecting part 21 and the second connecting part 42 is not limited to screwing; it can also be modified to a fitting, pressing, or locking structure.

[0121] The outer diameter of the second connecting portion 42 is smaller than the maximum outer diameter of the retaining portion 4. As a result, an annular stepped portion 46 is formed at the boundary between the maximum outer diameter portion 4a of the retaining portion 4 and the second connecting portion 42. This annular stepped portion 46 makes surface contact with the upper end of the upper shaft 2c of the pen barrel 2.

[0122] Two vent holes 44 are formed in the retaining part 4. The two vent holes 44 are symmetrically arranged on the cylindrical sidewall of the retaining part 4 and communicate with the internal space 41 of the retaining part 4. The vent holes 44 function as airflow paths for the child's breathing in the event that the child accidentally swallows the friction element unit 3. Furthermore, the first opening 44a of the vent holes 44 formed on the outer surface of the retaining part 4 (see reference...) Figure 7 It functions as an anti-slip part for the fingers holding the friction unit 3. This makes it easy to attach and detach the friction unit 3 from the pen barrel 2. Additionally, anti-slip parts such as grooves or knurling can be formed on the outer surface of the side wall of the retaining part 4, excluding the vent 44.

[0123] The vent 44 is located above the second joint 42, and the second opening 44b of the vent 44 (see reference) Figure 7 The vent 44 is located lower than the inward protrusion 45. This structure allows the vent 44 to penetrate the sidewall of the retaining portion 4 without interfering with the second connecting portion 42 or the inward protrusion 45. That is, the functions of the second connecting portion 42 and the inward protrusion 45 are not obstructed by the vent 44 penetrating the sidewall of the retaining portion 4. As a result, the second connecting portion 42 can reliably engage with the first connecting portion 21, and the inward protrusion 45 can reliably engage with the outward protrusion 54.

[0124] like Figure 12 As shown, the outer surface of the retaining part 4 is composed of a maximum outer diameter part 4a, a first tapered part 4b, a second tapered part 4c, a third tapered part 4d, and a chamfered part 4e. The first tapered part 4b is located above the maximum outer diameter part 4a. The second tapered part 4c is located above the first tapered part 4b. The third tapered part 4d is located above the second tapered part 4c. The chamfered part 4e is located above the third tapered part 4d. Furthermore, in the second embodiment, the lower end of the first tapered part 4b is the maximum outer diameter part 4a, and the maximum outer diameter part 4a does not have an outer surface.

[0125] The outer diameters of the first tapered portion 4b, the second tapered portion 4c, and the third tapered portion 4d all decrease from bottom to top. The outer diameter of the lowermost of the three tapered portions 4b, 4c, and 4d is preferably reduced by 10% to 30%. For example, the outer diameter of the lower end of the first tapered portion 4b (which is the same as the largest outer diameter portion 4a) is 10.0 mm, and the outer diameter of the upper end of the first tapered portion 4b is 8.8 mm.

[0126] The lower end of the second conical portion 4c has an outer diameter of 8.8 mm, and the upper end of the second conical portion 4c has an outer diameter of 6.8 mm. The tilt angle β of the second conical portion 4c is larger than the tilt angle α of the first conical portion 4b (α < β). For ease of gripping the holding portion 4, it is preferable that the tilt angle γ of the third conical portion 4d is smaller than the tilt angle β of the second conical portion 4c (γ < β). A vent 44 is formed in the second conical portion 4c. For example, it is set to α = 40°, β = 58°, and γ = 20°.

[0127] • Installation status of the friction element unit

[0128] like Figure 11 as well as Figure 12 As shown, the friction element unit 3 can be attached to and detached from the upper shaft 2c of the thermochromic writing instrument 1. Figure 11 As shown, when the friction body unit 3 is installed on the upper shaft 2c, the stepped portion 46 of the retaining portion 4 abuts against the upper end of the upper shaft 2c.

[0129] like Figure 12 As shown, in the second embodiment, the vent 44 is formed on the side wall of the retaining portion 4 where the second connecting portion 42 is not provided. As a result, the airflow path formed by the vent 44, the internal space 41, and the opening below the internal space 41 is completely unaffected by the unevenness of the external thread 43, allowing air to flow smoothly.

[0130] • Effects

[0131] In the friction unit 3 of the second embodiment described above, an airflow path communicating with the inside and outside of the holding part 4 is formed by the vent 44, the internal space 41, and the opening below the internal space 41. This airflow path ensures a child's airway even if the friction unit 3 is accidentally swallowed. In particular, by using the internal space 41 and the opening below as an airflow path, sufficient airflow can be achieved. This airflow path is formed from the outer surface of the side wall of the holding part 4 inwards, thus not restricting the design freedom of the holding part 4. Therefore, according to the structure of the second embodiment, the design freedom of the friction unit 3 and the thermochromic writing instrument 1 is increased.

[0132] In the friction element unit 3 of the second embodiment, the first opening 44a of the vent 44 is located in the portion of the cylindrical sidewall of the retaining portion 4 whose outer diameter is smaller than the maximum outer diameter portion 4a. Therefore, in the event that a child accidentally swallows the friction element unit 3, the maximum outer diameter portion 4a of the sidewall of the retaining portion 4 contacts the child's tracheal wall, while the portion with an outer diameter smaller than the maximum outer diameter portion 4a does not contact the child's tracheal wall. As a result, the first opening 44a of the vent 44 will not be blocked by the child's tracheal wall, ensuring the child's airway for breathing.

[0133] In the friction element unit 3 of the second embodiment, a first opening 44a of a vent 44 is formed in the second tapered portion 4c, whose outer diameter decreases from bottom to top. Therefore, in the event that a child accidentally swallows the friction element unit 3, the portion 4a with the maximum outer diameter of the retaining portion 4 contacts the child's tracheal wall, while the portion with an outer diameter smaller than the maximum outer diameter 4a does not contact the child's tracheal wall. As a result, the first opening 44a of the vent 44 will not be blocked by the child's tracheal wall, ensuring the child's airway for breathing.

[0134] The retaining portion 4 of the friction element unit 3 in the second embodiment has a sidewall comprising a maximum outer diameter portion 4a, a first conical portion 4b, and a second conical portion 4c. The second conical portion 4c has an outer diameter smaller than that of the first conical portion 4b and an inclination angle β larger than that of the first conical portion 4b. The first opening 44a of the vent 44 is formed in the second conical portion 4c. Therefore, in the event that a child accidentally swallows the friction element unit 3, even if the friction element unit 3 is tilted and causes the first conical portion 4b to come into contact with the child's tracheal wall, the second conical portion 4c will not come into contact with the child's tracheal wall. As a result, the first opening 44a of the vent 44 will not be blocked by the child's tracheal wall, ensuring the child's airway for breathing.

[0135] <Third Implementation Method>

[0136] Next, refer to Figures 13 to 21 The friction element unit and the thermochromic writing instrument according to the third embodiment of the present invention will be described.

[0137] like Figure 14 as well as Figure 15 As shown, the difference between the friction element unit 3 and the thermochromic writing instrument 1 of the third embodiment and those of the first and second embodiments lies in the structure of the holding part 4 of the friction element unit 3. In the following description of the friction element unit 3 and the thermochromic writing instrument 1 of the third embodiment, detailed descriptions of structures identical to those of the first embodiment are omitted.

[0138] ·pen

[0139] like Figure 13As shown, the pen barrel 2 of the thermochromic writing instrument 1 is composed of a lower shaft 2a, a middle shaft 2b, and an upper shaft 2c. The lower shaft 2a is mostly composed of a cylindrical portion. A tapered portion with a decreasing outer diameter from top to bottom is provided at the lower end of the cylindrical portion. The cylindrical portion of the lower shaft 2a serves as the grip of the thermochromic writing instrument 1. An opening is provided at the front end of the tapered portion of the lower shaft 2a. The pen tip of the refill extends and retracts from the opening at the front end of the tapered portion. The middle shaft 2b is composed only of a longer cylindrical portion. The lower end of the middle shaft 2b is connected to the upper end of the lower shaft 2a by screwing or pressing. The upper shaft 2c is composed only of a shorter cylindrical portion. The lower end of the upper shaft 2c is connected to the upper end of the middle shaft 2b by screwing or pressing. The lower shaft 2a, middle shaft 2b, and upper shaft 2c are formed, for example, of synthetic resins such as polycarbonate or metal.

[0140] like Figure 14 as well as Figure 15 As shown, a cylindrical first connecting part 21 protruding upward is provided at the upper end of the upper shaft 2c. An external thread 22 is provided on the outer surface of the first connecting part 21. The second connecting part 42 provided in the holding part 4 of the friction body unit 3 is screwed into the first connecting part 21. In addition, the connection between the first connecting part 21 and the second connecting part 42 is not limited to screwing, and can be changed to a fitting, pressing, or snap-fit ​​connection structure, for example.

[0141] The outer diameter of the first joint 21 is smaller than the outer diameter of the upper end of the upper shaft 2c. As a result, an annular step 23 is formed at the upper end of the upper shaft 2c. The lower end of the holding part 4 of the friction body unit 3 is in contact with the surface of this annular step 23.

[0142] • Friction body unit

[0143] Figures 14 to 21 This refers to friction element unit 3 in the third embodiment. For example... Figure 14 As shown, the friction unit 3 consists of a retaining part 4 and a friction body 5. The friction unit 3 is mounted on the upper shaft 2c of the pen barrel 2. The height of the friction unit 3 in the third embodiment is 15.0 mm.

[0144] • Maintenance Department

[0145] like Figures 15 to 20 As shown, a friction element 5 is mounted on the upper part 47 of the retaining part 4. The retaining part 4 is formed, for example, from a synthetic resin such as polycarbonate or from metal. The axial length of the retaining part 4 in the third embodiment is 9.0 mm.

[0146] like Figure 15As shown, the retaining part 4 has a cylindrical sidewall forming an internal space 41 that opens upwards and downwards. A second connecting part 42 is provided on the lower side of the retaining part 4. An internal thread 43 is provided on the inner surface of the second connecting part 42. This internal thread 43 engages with the external thread 22 of the first connecting part 21 of the pen barrel 2. In addition, the engagement between the first connecting part 21 and the second connecting part 42 is not limited to screwing; for example, it can be changed to a fitting, pressing, or snap-fit ​​engagement structure.

[0147] The friction body 5 is mounted on the upper part 47 of the retaining part 4. An annular inward protrusion 45 is provided on the inner surface of the upper part 47. On the other hand, an annular outward protrusion 54 is provided on the lower outer surface of the friction body 5. When the lower side of the friction body 5 is inserted into the upper part 47 of the retaining part 4, the inward protrusion 45 and the outward protrusion 54 are engaged. In addition, the connection between the retaining part 4 and the friction body 5 is not limited to the engagement of the inward protrusion 45 and the outward protrusion 54, and can also be fitting, pressing, locking, screwing, bonding, or two-color molding, etc.

[0148] The annular inward protrusion 45 has an inclined surface whose inner diameter decreases from top to bottom and an annular lower surface. The inclined surface of the inward protrusion 45 is guided downward toward the lower side of the friction body 5, which is inserted into the upper part 47 of the retaining part 4, toward the inner space 41. As a result, the outward protrusion 54 can be smoothly locked into the inward protrusion 45, making the assembly of the friction body unit 3 easier.

[0149] like Figure 15 , Figure 16 as well as Figure 20 As shown, three vent holes 44 are formed in the retaining part 4. The three vent holes 44 are equally spaced on the cylindrical sidewall of the retaining part 4 and communicate with the internal space 41 of the retaining part 4. The vent holes 44 function as airflow paths for the child's breathing in the event that the child accidentally swallows the friction element unit 3. Furthermore, the first opening 44a of the vent holes 44 formed on the outer surface of the retaining part 4 (see reference...) Figure 19 It functions as an anti-slip part for the fingers holding the friction unit 3. As a result, it is easy to attach and detach the friction unit 3 from the pen barrel 2.

[0150] And, as Figure 17 As shown, three tapered portions 4b, 4c, and 4d with different inclination angles α, β, and γ are provided on the outer surface of the retaining portion 4. By ensuring that the inclination angles α, β, and γ of the three tapered portions 4b, 4c, and 4d are all less than 45°, it is easy to grip with fingers from any position on the side wall of the retaining portion 4. This facilitates the attachment and removal of the friction element unit 3 from the pen barrel 2. Furthermore, anti-slip features such as grooves or knurled areas can be formed on the outer surface of the side wall of the retaining portion 4, excluding the vent hole 44.

[0151] like Figure 15 as well as Figure 19 As shown, the vent 44 has a first opening 44a formed on the outer surface of the sidewall of the retaining portion 4 and a second opening 44b formed on the inner surface of the sidewall of the retaining portion 4. The vent 44 is positioned higher than the second connecting portion 42, and the second opening 44b of the vent 44 is positioned lower than the inward protrusion 45. With this structure, the vent 44 penetrates the sidewall of the retaining portion 4 without interfering with the second connecting portion 42 and the inward protrusion 45. That is, the functions of the second connecting portion 42 and the inward protrusion 45 are not obstructed by the vent 44 penetrating the sidewall of the retaining portion 4. As a result, the second connecting portion 42 can be reliably screwed into the first connecting portion 21, and the inward protrusion 45 can be reliably engaged with the outward protrusion 54.

[0152] For example Figure 16 as well as Figure 19 As shown, the first opening 44a of the vent 44 is formed on the inclined surface of the second conical portion 4c, where the outer diameter decreases from bottom to top. Therefore, a [missing information - likely a typo, should be inserted here] is generated between the upper and lower ends of the first opening 44a of the vent 44. Figure 16 The diameter difference A shown allows the interior of the vent 44 to expand from the second opening 44b to the first opening 44a. Therefore, even if a child accidentally swallows the friction element unit 3, a sufficient amount of air can be obtained from the vent 44. Figure 16 The diameter difference A shown is preferably 0.5 mm or more.

[0153] like Figure 17 as well as Figure 18 As shown, the outer surface of the retaining part 4 is composed of a maximum outer diameter part 4a, a first tapered part 4b, a second tapered part 4c, a third tapered part 4d, and two chamfered parts 4e. The first tapered part 4b is located above the maximum outer diameter part 4a. A first chamfered part 4e is formed between the first tapered part 4b and the second tapered part 4c. The second tapered part 4c is located above the chamfered part 4e. The third tapered part 4d is located above the second tapered part 4c. A second chamfered part 4e is formed above the third tapered part 4d. Furthermore, in the third embodiment, the lower end of the first tapered part 4b is the maximum outer diameter part 4a, and the maximum outer diameter part 4a does not have an outer surface.

[0154] The outer diameters of the first tapered portion 4b, the second tapered portion 4c, and the third tapered portion 4d all decrease from bottom to top. In the third embodiment, the outer diameter of the lower end of the first tapered portion 4b (which is the same as the largest outer diameter portion 4a) is 10.2 mm, and the outer diameter of the upper end of the first tapered portion 4b is 10.0 mm.

[0155] The lower end of the second conical portion 4c has an outer diameter of 9.7 mm, and the upper end has an outer diameter of 6.8 mm. The inclination angle β of the second conical portion 4c is larger than the inclination angle α of the first conical portion 4b (α < β). For easy handling of the holding portion 4, it is preferable that the inclination angle γ of the third conical portion 4d is smaller than the inclination angle β of the second conical portion 4c (γ < β). A vent 44 is formed in the second conical portion 4c. For example, it is set to α = 3.2°, β = 44°, and γ = 11°. Alternatively, the first conical portion 4b, the second conical portion 4c, and the third conical portion 4d can also be cones with very small inclination angles, such as the draft angle for easy removal of the molded part from the mold. In addition, the ends that form the boundary between the second conical portion 4c and the third conical portion 4d can also be chamfered.

[0156] exist Figure 21 The diagram shows the central angles θ1, θ2, and θ3 of the first opening 44a of the three vent holes 44. The central angles θ1, θ2, and θ3 of the first opening 44a are the angles formed by two imaginary lines connecting the two outermost ends of the first opening 44a to the center point of the retaining part 4. The sum θ (θ = θ1 + θ2 + θ3) of the central angles θ1, θ2, and θ3 of the first opening 44a is preferably in the range of 90° to 180°, more preferably in the range of 90° to 150°. This is because if the sum θ is less than 90°, sufficient ventilation cannot be obtained, and if the sum θ exceeds 180° (more preferably 150°), sufficient strength of the retaining part 4 cannot be obtained.

[0157] exist Figure 17 The height C of the second opening 44b of the vent 44 is shown. The height C of the second opening 44b is preferably 0.5 mm or more. This is because if the height C of the second opening 44b is 0.5 mm or more, sufficient ventilation can be obtained in the event that a child accidentally swallows the friction element unit 3.

[0158] like Figure 15 as well as Figure 18 As shown, in the third embodiment, the sidewall portion 4f extending from the upper end of the first opening 44a of the vent 44 to the upper end of the second opening 44b has a constant outer diameter. The outer diameter of the sidewall portion 4f is the same as the outer diameter of the upper end of the first opening 44a. With this sidewall portion 4f, the outer diameter of the portion of the sidewall of the retaining part 4 that is higher than the upper end of the second opening 44b of the vent 44 becomes less than or equal to the outer diameter of the upper end of the second opening 44b. Therefore, in the event that a child accidentally swallows the friction element unit, the portion higher than the upper end of the second opening of the vent 44 will not come into contact with the child's tracheal wall. As a result, a larger gap is formed between the portion higher than the upper end of the second opening of the vent 44 and the child's tracheal wall, ensuring a safe airway for the child's breathing.

[0159] Furthermore, the outer diameter of the portion above the upper end of the second opening 44b of the vent 44 is the outer diameter of the upper end of the second opening 44b. This means that when the shape of the retaining part 4 is formed using a mold, there is no undercut in the vent 44. Therefore, the shape of the retaining part 4 can be injection molded using a single, undivided mold, eliminating the need for a sliding core to form the vent 44. As a result, the cost of injection molding the retaining part 4 can be reduced.

[0160] • Installation status of the friction element unit

[0161] like Figure 14 as well as Figure 15 As shown, the friction element unit 3 can be attached to and detached from the upper shaft 2c of the thermochromic writing instrument 1. Figure 14 As shown, when the friction body unit 3 is mounted on the upper shaft 2c, the lower end of the retaining part 4 abuts against the stepped part 23 of the upper shaft 2c. Furthermore, similar to the second embodiment described above, a structure can also be adopted in the third embodiment where the upper shaft 2c has an internal thread 22 and the retaining part 4 has an external thread 43.

[0162] • Effects

[0163] In the friction element unit 3 of the third embodiment described above, an airflow path communicating with the inside and outside of the holding part 4 is formed by the vent 44, the internal space 41, and the opening below the internal space 41. This airflow path ensures a child's airway even if the friction element unit 3 is accidentally swallowed. In particular, by using the internal space 41 and the opening below as an airflow path, sufficient airflow can be achieved. This airflow path is formed from the outer surface of the side wall of the holding part 4 inwards, thus not restricting the design freedom of the holding part 4. Therefore, according to the structure of the third embodiment, the design freedom of the friction element unit 3 and the thermochromic writing instrument 1 is increased.

[0164] In the friction element unit 3 of the third embodiment, the first opening 44a of the vent 44 is located in the portion of the cylindrical sidewall of the retaining portion 4 whose outer diameter is smaller than the maximum outer diameter portion 4a. Therefore, in the event that a child accidentally swallows the friction element unit 3, the maximum outer diameter portion 4a of the sidewall of the retaining portion 4 contacts the child's tracheal wall, while the portion with an outer diameter smaller than the maximum outer diameter portion 4a does not contact the child's tracheal wall. As a result, the first opening 44a of the vent 44 will not be blocked by the child's tracheal wall, ensuring the child's airway for breathing.

[0165] In the friction body unit 3 of the third embodiment, a first opening 44a of a vent 44 is formed in the second tapered portion 4c, whose outer diameter decreases from bottom to top. Therefore, in the event that a child accidentally swallows the friction body unit 3, the portion 4a with the maximum outer diameter of the retaining portion 4 contacts the child's tracheal wall, while the portion with an outer diameter smaller than the maximum outer diameter 4a does not contact the child's tracheal wall. As a result, the first opening 44a of the vent 44 will not be blocked by the child's tracheal wall, ensuring the child's airway for breathing.

[0166] The retaining portion 4 of the friction element unit 3 in the third embodiment has a sidewall comprising a maximum outer diameter portion 4a, a first conical portion 4b, and a second conical portion 4c. The second conical portion 4c has an outer diameter smaller than that of the first conical portion 4b and an inclination angle β larger than that of the first conical portion 4b. The first opening 44a of the vent 44 is formed in the second conical portion 4c. Therefore, in the event that a child accidentally swallows the friction element unit 3, even if the friction element unit 3 is tilted and causes the first conical portion 4b to come into contact with the child's tracheal wall, the second conical portion 4c will not come into contact with the child's tracheal wall. As a result, the first opening 44a of the vent 44 will not be blocked by the child's tracheal wall, ensuring the child's airway for breathing.

[0167] In the friction body unit 3 of the third embodiment, the outer diameter of the portion above the upper end of the second opening 44b of the vent 44 is less than or equal to the outer diameter of the upper end of the second opening 44b. Therefore, when the shape of the retaining part 4 is formed using a mold, there is no undercut in the vent 44. As a result, the shape of the retaining part 4 can be injection molded using a single, undivided mold, eliminating the need for a sliding core to form the vent 44. Consequently, the cost of injection molding the retaining part 4 can be reduced.

[0168] In the thermochromic writing instrument 1 of the third embodiment, the annular outward protrusion 54 and the inward protrusion 45 are locked together within a 360-degree range, thereby firmly holding the mounting portion 52 of the friction body 5 within the internal space 41 of the holding portion 4. Furthermore, with the outward protrusion 54 and the inward protrusion 45 locked together, a gap is formed between the outer surface of the outward protrusion 54 and the inner surface of the holding portion 4. This gap communicates with the vent 44, maintaining an airflow path that connects the inside and outside of the holding portion 4.

[0169] Furthermore, the airflow path of the friction element unit 3 functions in the event that a child accidentally swallows the friction element unit 3 after it has been removed from the thermochromic writing instrument 1. On the other hand, when the friction element unit 3 is installed on the thermochromic writing instrument 1, the airflow path of the friction element unit 3 does not function. Therefore, in the third embodiment, the structure in which the first connecting portion 21 of the thermochromic writing instrument 1 is housed within the gap constituting a part of the airflow path of the friction element unit 3 can effectively utilize this gap.

[0170] <Fourth Implementation Method>

[0171] Next, refer to Figure 22 The friction element unit and the thermochromic writing instrument according to the fourth embodiment of the present invention will be described.

[0172] like Figure 22 As shown, in the fourth embodiment, the friction body unit 3 has a plurality of recesses 48 formed along the lower end of the cylindrical sidewall of the retaining portion 4. The plurality of recesses 48 are formed on the inner surface of the lower end of the retaining portion 4. Thus, the lower end of the retaining portion 4 has a shape in which the plurality of recesses 48 and protrusions 49 alternately and continuously. Alternatively, the plurality of recesses 48 and protrusions 49 may also be formed on the outer surface of the lower end of the retaining portion 4. In the fourth embodiment, the structure other than the recesses 48 and protrusions 49 is similar to... Figures 13 to 21 The friction element 3 shown is the same as the thermochromic writing instrument 1.

[0173] • Effects

[0174] First, the plurality of recesses 48 are used to maintain the posture of the holding part 4 during the automated assembly process of the friction body unit 3. That is, the plurality of recesses 48 are engaged with the plurality of protrusions formed in the clamp (not shown). As a result, the movement and rotation of the holding part 4 are restricted, and the friction body 5 can be easily assembled into the holding part 4.

[0175] Second, the multiple recesses 48 and the retaining portion 4 are securely engaged with the barrel 2 of the thermochromic writing instrument 1. That is, the friction unit 3 is mounted on... Figure 15 The first joint 21 of the upper shaft 2c is shown. At this time, the lower end of the side wall of the retaining part 4 is in contact with the annular stepped part 23 of the upper shaft 2c. Under the condition of high surface contact pressure and large contact area, the lower end of the side wall of the retaining part 4 is firmly engaged with the stepped part 23 of the upper shaft 2c, and sometimes it is impossible to disassemble the friction body unit 3 by hand. The multiple recesses 48 reduce the area of ​​the lower end of the side wall of the retaining part 4, making it easier to disassemble the friction body unit 3 by hand.

[0176] Furthermore, the multiple recesses 48 receive foreign objects such as dust or dirt between the lower end of the sidewall of the retaining portion 4 and the stepped portion 23 of the upper shaft 2c, ensuring that foreign objects do not obstruct the installation of the friction element unit 3. Additionally, multiple protrusions (not shown) can be formed on the stepped portion 23 of the upper shaft 2c. When the friction element unit 3 is installed on the upper shaft 2c, the multiple recesses 48 engage with the multiple protrusions formed on the stepped portion 23, restricting the rotation of the retaining portion 4. This allows for the maintenance of... Figure 14 The engagement of the first joint 21 and the second joint 42 shown in the diagram prevents the friction body unit 3 from accidentally separating from the upper shaft 2c.

[0177] <Other>

[0178] The friction element unit and thermochromic writing instrument of the present invention are not limited to the structures of the first to fourth embodiments described above. For example, the friction element unit is not limited to telescopic thermochromic writing instruments, but can be applied to pen-cap type thermochromic writing instruments. In this case, the friction element unit is mounted on the end of the pen cap opposite to the opening. Furthermore, the thermochromic writing instrument using the friction element unit is not limited to ballpoint pens. The friction element unit can be applied, for example, to thermochromic writing instruments other than ballpoint pens such as pencils or markers.

[0179] Explanation of reference numerals in the attached figures

[0180] 1. Thermochromic writing instruments

[0181] 2 pen barrels

[0182] 2a lower shaft

[0183] 2b central axis

[0184] 2c upper shaft

[0185] 2D pen clip

[0186] 21 First junction

[0187] 22 External thread, internal thread

[0188] 23 steps

[0189] 24 Expanded Diameter Section

[0190] 3 friction body units

[0191] 4. Holding section

[0192] 41 Interior Space

[0193] 42 Second joint

[0194] 43 Internal thread, external thread

[0195] 44 vents

[0196] 44a First opening

[0197] 44b Second Opening

[0198] 45 Inward protrusion

[0199] 46 steps

[0200] 47 upper part

[0201] 48 concavity

[0202] 49 convex part

[0203] 4a Maximum outer diameter section

[0204] 4b First conical part

[0205] 4c Second Conical Part

[0206] 4d third cone part

[0207] 4e chamfered part

[0208] 4f sidewall portion

[0209] 5 friction body

[0210] 51 Friction Section

[0211] 52 Installation Department

[0212] 53 steps

[0213] 54 outward protrusions

Claims

1. A friction element unit comprising a friction element and a retaining portion, the friction element being configured to generate frictional heat for thermochromic ink to change the color of the writing, the retaining portion having an upper portion and a connecting portion, the upper portion holding the friction element, and the connecting portion being detachably connected to the barrel or cap of a thermochromic writing instrument, characterized in that... The maximum outer diameter of the friction element is smaller than the outer diameter of the upper end of the retaining part. The retaining part has a cylindrical sidewall that forms an internal space with at least a downward opening. At least one vent is formed on the sidewall, which opens at a position higher than the joint and offset inward from the maximum outer diameter of the sidewall, and communicates with the internal space. Air can flow between the vent, the interior space, and the opening below.

2. The friction element unit as described in claim 1, characterized in that, The cylindrical sidewall of the retaining part includes a portion with a large outer diameter and a portion with a small outer diameter. The vent has a first opening formed on the outer surface of the sidewall and a second opening formed on the inner surface of the sidewall, with at least the first opening located above the maximum outer diameter portion.

3. The friction element unit as described in claim 2, characterized in that, At least a portion of the cylindrical sidewall of the retaining part is provided with a tapered portion whose outer diameter decreases from bottom to top, and the first opening of the vent is formed in the tapered portion.

4. The friction element unit as described in claim 3, characterized in that, The cylindrical sidewall of the retaining part includes a first tapered portion located above the maximum outer diameter portion and a second tapered portion located above the first tapered portion. The outer diameter of the first tapered portion decreases upward from the upper end of the maximum outer diameter portion, and the outer diameter of the second tapered portion decreases upward from the upper end of the first tapered portion. The inclination angle of the second tapered portion is larger than the inclination angle of the first tapered portion, and the first opening of the vent is formed in the second tapered portion.

5. The friction element unit as described in claim 3, characterized in that, The outer diameter of the portion of the cylindrical sidewall of the retaining part that is above the upper end of the second opening of the vent is less than the outer diameter of the upper end of the second opening.

6. The friction element unit as described in any one of claims 2 to 5, characterized in that, An annular outward protrusion is provided on the lower outer surface of the friction body. An annular inward protrusion is provided on the inner surface of the cylindrical sidewall of the retaining part, and the sidewall opens downward and upward. At least the second opening of the vent is located lower than the inward protrusion. With the friction body inserted into the internal space through the opening above the sidewall on its lower side, the outward protrusion engages with the inward protrusion. When the outward protrusion and the inward protrusion are locked together, a gap is formed between the outer surface of the outward protrusion and the inner surface of the sidewall, and the gap communicates with the vent.

7. The friction element unit as described in any one of claims 1 to 5, characterized in that, Multiple recesses are formed along the lower end of the cylindrical sidewall of the retaining part.

8. The friction element unit as described in claim 6, characterized in that, Multiple recesses are formed along the lower end of the cylindrical sidewall of the retaining part.

9. A thermochromic writing instrument comprising the friction element unit as described in any one of claims 1 to 5 and 8, characterized in that, The thermochromic writing instrument has a first connecting part in the barrel or cap. The friction body unit is provided with a second joint that is configured to be detachable from the first joint.

10. A thermochromic writing instrument comprising the friction element unit as described in claim 6, characterized in that, The thermochromic writing instrument has a first connecting part in the barrel or cap. The friction body unit is provided with a second joint that is configured to be detachable from the first joint.

11. A thermochromic writing instrument comprising the friction element unit as described in claim 7, characterized in that, The thermochromic writing instrument has a first connecting part in the barrel or cap. The friction body unit is provided with a second joint that is configured to be detachable from the first joint.

12. A thermochromic writing instrument comprising the friction element unit as described in claim 6, characterized in that, The thermochromic writing instrument has a first connecting part in the barrel or cap. The friction element unit is provided with a second coupling portion configured to be detachable from the first coupling portion. When the second joint is engaged with the first joint, the first joint is located in the gap formed between the outer surface of the outwardly protruding part and the inner surface of the sidewall.

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