Disappearance-style notebook

Abstract

To provide a retractable writing instrument which prevents rattling of a tip in writing and provides stable writing feeling, is unsusceptible to actuation failure, and can keep a smoothly protruding operation for an extended period.SOLUTION: A retractable writing instrument includes a barrel having an opening in a front end thereof, a tip holder which can move in an axial direction of the barrel, a tip which can retract along with a movement of the tip holder, an annular member which is fitted in an inner periphery of the opening of the barrel with a play therebetween and can move in the axial direction, and an elastic member which can connect the tip holder and the annular member to each other with their relative movement allowed. An abutment surface tapered toward a front end is formed in at least part of an outer periphery of the annular member. A cutout is formed in part of the annular member. The annular member is configured such that when receiving a load on the abutment surface, an inner diameter of the annular member is reduced. A surface in the rear of a protrusion part of an inner surface of the barrel is perpendicular to the axial direction, and comes into abutment contact with a flange part in an outer periphery of the annular member to define a movement limit of a front side of the annular member.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a retractable writing instrument in which a chip can protrude and retract from an opening of a shaft cylinder as the chip holder moves.

Background Art

[0002] Patent Document 1 discloses a device for preventing the tip of a writing instrument from wobbling. The configuration of the device is such that a concave groove is provided at an appropriate position of the writing tip portion, and an O-ring having an outer diameter substantially equal to the inner diameter of the tip portion of the shaft cylinder is fitted into the concave groove. According to this device, in a pencil type and a knock-type writing instrument, it is possible to prevent the rattling sound that occurs when the writing tip portion at the time of writing abuts against the tip hole of the tip portion of the shaft cylinder.

[0003] Patent Document 2 also discloses a device for preventing the tip of a writing instrument from wobbling. The configuration of the device is such that an elastic ring having an inner diameter slightly smaller than the outer diameter of the writing tip portion is engaged with a locking step portion provided inside the tip of the shaft cylinder. According to this device, since the elastic ring locks the writing tip portion, even if there is a gap between the inner diameter of the tip of the shaft cylinder and the writing tip portion, it is possible to prevent rattling during writing.

[0004] Patent Document 3 discloses a writing instrument that slides in the front-rear direction with respect to a shaft cylinder and feeds out a writing portion of a writing body from an opening of the shaft cylinder. An annular member is disposed on the outer periphery of the tip portion of the writing body, and a substantially spherical inner surface with which the annular member abuts is formed on the inner surface around the opening of the tip of the shaft cylinder where the writing portion protrudes and retracts. The annular member is fixed to the writing body via a spring and is biased forward. When the writing portion is fed out, the annular member is brought into close contact with the inner surface of the tip of the shaft cylinder by the elastic force of the spring. Thereby, it is possible to prevent rattling during writing.

[0005] Patent Document 4 by the applicant of the present application discloses four types of configurations as a retractable writing instrument that prevents the chip from rattling.

[0006] Furthermore, Patent Document 5 by the applicant discloses a retractable writing instrument configuration that improves upon the problems of Patent Documents 1 to 4 (however, Patent Document 5 (and its contents) were not published at the time of filing this application).

[0007] Figure 8 is a schematic longitudinal cross-sectional view of the retractable writing instrument 10 in the first embodiment of Patent Document 5, showing the state in which the tip 14 (cursive writing instrument) is not protruding. Figure 9 is an enlarged longitudinal cross-sectional view of the tip portion of the retractable writing instrument 10 of the said embodiment.

[0008] Furthermore, Figure 10(a) is a perspective view of the annular member 15 of the retractable writing instrument 10 of this embodiment, Figure 10(b) is a plan view of the annular member 15 of Figure 10(a), Figure 10(c) is a side view of the annular member 15 of Figure 10(a), Figure 10(d) is a bottom view of the annular member of Figure 10(a), Figure 10(e) is a cross-sectional view of line AA of Figure 10(c), Figure 10(f) is a front view (viewed from the tip side) of the annular member of Figure 10(a), and Figure 10(g) is a rear view of the annular member of Figure 10(a).

[0009] Furthermore, Figure 11 is a schematic diagram showing the state in which the tip 14 is in contact with the annular member 15 during the process of extending the tip 14 in the retractable writing instrument 10 of this embodiment, Figure 12 is a schematic diagram showing the state in which the tip 14 is most extended during the process of extending the tip 14 in the retractable writing instrument 10 of this embodiment, and Figure 13 is a schematic diagram showing the state in which the tip 14 is extended after the extension operation of the tip 14 has been completed in the retractable writing instrument 10 of this embodiment.

[0010] The retractable writing instrument 10 of the first embodiment shown in Figures 8 to 13 comprises a cylindrical barrel 11 having an opening at its front end. As shown in Figures 8 to 10, in this embodiment, the barrel 11 has a rear portion 11r and a front portion 11m. The rear portion 11r and the front portion 11m are detachably fixed by screw connection (screw-in). However, the rear portion 11r and the front portion 11m may be fixed by a fit connection or may be formed integrally.

[0011] Inside the barrel 11 is a tip holder 13 that is movable in the axial direction of the barrel 11. A cursive tip 14 is fixed to the front end of the tip holder 13. As the tip holder 13 moves, the tip 14 can extend and retract from the opening of the barrel 11, as shown in Figures 11 to 13.

[0012] As shown in Figure 9, the tip holder 13 has a base portion 13a, a first collar portion 13b, and a second collar portion 13c in that order from the base end to the tip end. In this embodiment, both the base portion 13a and the first collar portion 13b are cylindrical, and the second collar portion 13c is a truncated cone in this embodiment, and the relationship between their cross-sectional diameters is base portion 13a > first collar portion 13b > second collar portion 13c.

[0013] In this embodiment, as shown in Figure 9, an annular member 15 is loosely fitted to the inner circumference of the opening of the shaft cylinder 11, and is movable in the axial direction of the shaft cylinder 11. The front end of the annular member 15 is located further forward than the front end of the shaft cylinder 11. The rear side of the annular member 15 is enlarged in both its outer and inner diameters, and non-contactly covers the area around the tip 14 (φ2.5).

[0014] Furthermore, the annular member 15 is fixed to the front end of the coil spring 16 (an example of an elastic member). The coil spring 16 loosely surrounds the second collar portion 13c and the tip 14 of the tip holder 13 (with a gap), and the rear end of the coil spring 16 is constantly pressed (not fixed) by the base end portion 13a of the tip holder 13. In this way, the coil spring 16 connects the tip holder 13 and the annular member 15 so that they can move relative to each other. As shown in Figures 11 to 13, the annular member 15 is movable in the axial direction of the shaft cylinder 11 in accordance with the movement of the tip holder 13 and the expansion and contraction deformation of the coil spring 16.

[0015] The annular member 15 is made of resin (e.g., polyacetal, polypropylene, polyethylene) or metal (e.g., brass).

[0016] Furthermore, as shown in Figures 10(a) to 10(g), the outer surface of the annular member 15 is provided in the following order from the front: a small outer diameter cylindrical surface 15a (φ3.6 mm, axial length 1.6 mm), a first truncated cone outer surface 15b (axial length 1.1 mm) as a tapered contact surface, a medium outer diameter cylindrical surface 15c (φ4.85 mm, axial length 1.5 mm), a second truncated cone outer surface 15d (axial length 1.6 mm) as a tapered contact surface, a first large outer diameter cylindrical surface 15e (φ6.3 mm, axial length 0.8 mm), a third truncated cone outer surface 15f (axial length 0.4 mm) as a tapered contact surface, and a second large outer diameter cylindrical surface 15g (φ6.6 mm, axial length 3.3 mm).

[0017] Furthermore, as shown in Figure 10(e), the inner circumferential surface of the annular member 15 is provided in the following order from the front: a small inner diameter cylindrical surface 15ia (φ3.0 mm, axial length 2 mm), a first truncated cone inner surface 15ib (axial length 0.5 mm), a medium inner diameter cylindrical surface 15ic (φ3.6 mm, axial length 3.9 mm), a second truncated cone inner surface 15id (axial length 0.4 mm), a four-sided blunt section 15ie (inscribed circle φ5.28 mm, axial length 0.9 mm), a large inner diameter cylindrical surface 15if (φ5.43 mm, axial length 2.1 mm), and a third truncated cone inner surface 15ig (axial length 0.4 mm). As shown in Figure 9, in this embodiment, the front end of the coil spring 16 is fixed (fitted and fixed) on the four-sided blunt section 15ie.

[0018] Furthermore, the annular member 15 of this embodiment is provided with three slits 15s as notches. As shown in Figures 10(a) to 10(g), the three slits 15s are arranged at equal intervals (120° apart) in the circumferential direction of the annular member 15. Each of the three slits 15s has a width of 0.8 mm and extends in the axial direction of the annular member 15 from the front end to approximately the center of the outer surface 15d of the second truncated cone (maximum axial length of 5.5 mm).

[0019] As a result, when a load is applied to the outer surface 15b (contact surface) of the first truncated cone, the inner diameter of the annular member 15 flexibly shrinks, and when the load is released, the inner diameter of the annular member 15 elastically returns to its original state.

[0020] On the other hand, as shown in Figures 9, 12, or 13, the inner circumferential surface near the opening of the shaft cylinder 11 is provided with the following surfaces in the order shown, from the front: a small inner diameter cylindrical surface 11ia (φ3.7 mm, axial length 1.2 mm), a first truncated cone inner surface 11ib (axial length 1.1 mm) as a tapered guide surface, a medium inner diameter cylindrical surface 11ic (φ4.95 mm, axial length 1.3 mm), a second truncated cone inner surface 11id (axial length 1.7 mm) as a tapered guide surface, a first large inner diameter cylindrical surface 11ie (φ6.5 mm, axial length 0.8 mm), a third truncated cone inner surface 11if (axial length 0.3 mm), a second large inner diameter cylindrical surface 11ig (φ6.7 mm, axial length 4.2 mm), and an annular projection 11ih (minimum aperture diameter φ6.5 mm) as a regulating element.

[0021] As a result, the outer surface 15b (contact surface) of the first truncated cone receives loads from the inner surface 11ib of the first truncated cone and the inner surface 11id of the second truncated cone (guide surfaces) as the tip holder 13 moves toward the front end.

[0022] Furthermore, the coil spring 16 in this embodiment also has the function of automatically retracting the tip holder 13 when the tip 14 is retracted (for example, by sliding the operating part provided on the side of the writing instrument to release the locking mechanism that maintains the protruding state of the tip 14). In other words, the coil spring 16 functions as a so-called knock spring. (The operating load is approximately 50gf to 300gf (approximately 0.49N to 2.94N). For example, the operating load from the non-use state (Figure 9) is 68gf, the load at full stroke (Figure 12) is 288gf, and the operating load from the writing state (Figure 13) is 227gf. The spring constant is 0.23N / mm.)

[0023] The retractable writing instrument 10, having the configuration described above, operates as follows.

[0024] When not in use, the tip 14 (cursive) of the retractable writing instrument 10 is in a retracted state as shown in Figures 8 and 9. At this time, the axial length of the coil spring 16 is 17 mm, the annular member 15 is not reduced in diameter, and the small inner diameter cylindrical surface 15ia of the annular member 15 remains φ3.0 (> outer diameter of the tip 14).

[0025] Then, when the tip is extended (for example, by sliding the operating part provided on the side of the writing instrument), the tip 14 (cursive writing tip) of the retractable writing instrument 10 reaches the state shown in Figure 11.

[0026] In the state shown in Figure 11, the protruding operation of the tip 14 moves the second collar portion 13c of the tip holder 13 forward. As a result, the annular member 15 is moved forward to the inner surface of the shaft cylinder 11 via the coil spring 16 and is further pressed against the front of the inner surface, causing the outer surface 15b (contact surface) of the first truncated cone to receive a load from the inner surface 11ib (guide surface) of the first truncated cone, and the inner diameter of the annular member 15 is reduced due to the presence of the three slits 15s of the annular member 15.

[0027] The inner diameter when the tip is retracted corresponds to the outer diameter of the tip 14. That is, the minimum inner diameter when the tip is retracted (for example, about 2.35 mm to 2.45 mm) is such that it allows smooth sliding of the tip 14 (for example, φ2.5 mm) in the axial direction, while providing an effective anti-vibration effect for the tip 14 in the radial direction. Furthermore, even if the outer diameter of the tip 14 is smaller (for example, φ2.4 mm) or larger (for example, φ2.6 mm) than the aforementioned φ2.5 mm, the same (same dimensions) annular member 15 can provide a similarly effective anti-vibration effect. In other words, the retractable writing instrument 10 of this embodiment is compatible with different types of refills having different tip outer diameters in terms of anti-vibration effect. This improves user convenience.

[0028] In this embodiment, the outer surface 15d of the second truncated cone contacts the inner surface 11id of the second truncated cone, thereby defining the limit of forward movement of the annular member 15. That is, in this embodiment, the outer surface 15d of the second truncated cone of the annular member 15 and the inner surface 11id of the second truncated cone of the shaft cylinder 11 function as stopper elements that define the limit of forward movement of the annular member 15. However, such a stopper element can be omitted.

[0029] Subsequently, when the protruding operation of the tip (for example, the sliding operation of the operation portion provided on the side surface of the writing instrument) continues, the tip 14 (writing body) of the retractable writing instrument 10 reaches the state shown in FIG. 12.

[0030] When the protruding operation of the tip ends (for example, the sliding operation of the operation portion provided on the side surface of the writing instrument is released), the tip 14 (writing body) of the retractable writing instrument 10 reaches the state shown in FIG. 13. Normally, in the protruding state of FIG. 13, the position of the tip holder 13 is locked, and the protruding state of the tip 14 is maintained until the tip is retracted. At this time, the axial length of the coil spring 16 is 9.9 mm (compressed by 10.1 mm), and the annular member 15 is maintained in a reduced diameter state by the restoring force of the coil spring 16. Thereby, the tip 14 can be gripped in a manner without play.

[0031] Here, even when the stopper element that defines the limit of forward movement of the annular member 15 functions, when the dimension of the small inner diameter cylindrical surface 15ia on the inner peripheral surface of the annular member 15 is sufficiently smaller than the outer diameter of the tip 14 (when the diameter difference is about 0.05 mm or more: refer to paragraph 0100), the tip holder 13 and the annular member 15 are connected to each other by the coil spring 16 so as to be relatively movable. Thus, even without highly precise dimensional management of the degree of reduction in the inner diameter of the annular member 15, it is possible to effectively grip the tip 14 in a manner without play.

[0032] Subsequently, when the tip is retracted (for example, by resliding the operating part located on the side of the writing instrument), a locking mechanism (not shown) is released, and the tip 14 (cursive) of the retractable writing instrument 10 returns to the state shown in Figure 12. Furthermore, due to the action of the coil spring 16 (restoring force), it returns to the retracted state shown in Figure 9, via the state shown in Figure 11.

[0033] In the process from the state shown in Figure 11 to the immersed state shown in Figure 9, the tip holder 13 is moved to the rear, so the load that the outer surface 15b (contact surface) of the first truncated cone was receiving from the inner surface 11ib (guide surface) of the first truncated cone disappears. Consequently, the inner diameter of the annular member 15, which had been reduced in diameter, returns to its original state.

[0034] Furthermore, during the aforementioned process of extending and retracting the tip, the contact surface of the annular member 15 (the outer surface 15b of the first truncated cone) and the guide surface of the shaft cylinder 11 (the inner surface 11ib of the first truncated cone) are always in contact.

[0035] As described above, with the retractable writing instrument 10 of this embodiment, as the tip holder 13 moves toward the front end, the contact surface of the annular member 15 (the outer surface of the first truncated cone 15b) receives a load from the guide surface of the barrel 11 (the inner surface of the first truncated cone 11ib), causing the inner diameter of the annular member 15 to shrink due to the presence of the slit 15s in the annular member 15. As a result, the barrel 11 and the annular member 15 cooperate to grip the tip 14 without any looseness (play). Furthermore, in the retractable writing instrument 10 of this embodiment, a stopper element that defines the limit of the forward movement of the annular member 15 functions, but because the dimension of the small inner diameter cylindrical surface 15ia on the inner circumferential surface of the annular member 15 is sufficiently smaller than the outer diameter of the tip 14 (the diameter difference is about 0.05 mm or more: see paragraph 0100), the tip holder 13 and the annular member 15 are connected to each other so as to be able to move relative to each other by the coil spring 16, it is possible to ensure that the tip 14 is gripped effectively without looseness (play) without requiring high-precision dimensional control regarding the degree of reduction in the inner diameter of the annular member 15.

[0036] Furthermore, according to the retractable writing instrument 10 of this embodiment, the three slits 15s, which serve as notches, are arranged at equal intervals in the circumferential direction of the annular member 15, and each slit 15s extends in the axial direction of the annular member 15, so that the inner diameter of the annular member 15 can be reduced in a well-balanced manner in the circumferential direction.

[0037] Furthermore, since the contact surface of the annular member 15 (first truncated cone outer surface 15b) and the guide surface of the shaft cylinder 11 (first truncated cone inner surface 11ib) are corresponding truncated cone outer and truncated cone inner surfaces, the contact surface of the annular member 15 can receive loads in a balanced manner in the circumferential direction, and as a result, the annular member 15 can be reduced in diameter in a balanced manner in the circumferential direction. In this way, it is preferable that the contact surface of the annular member 15 (first truncated cone outer surface 15b) and the guide surface of the shaft cylinder 11 (first truncated cone inner surface 11ib) are tapered toward the front end. The tapered contact surface has a convex surface that is rotationally symmetrical about the axis, and the tapered guide surface may be a concave surface or a concave truncated cone surface that is rotationally symmetrical about the axis and has a curvature gentler than the curvature of the convex surface.

[0038] Furthermore, the degree of elasticity (ease of diameter reduction) of the annular member 15 can be adjusted by appropriately changing the number, size, shape, etc. of the slits 15s. In addition, the degree of elasticity (ease of diameter reduction) of the annular member 15 can also be adjusted by changing the material and / or wall thickness of the annular member 15.

[0039] Furthermore, in this embodiment, an annular projection 11ih is provided on the inner circumferential surface of the shaft cylinder 11, defining the rearward limit of movement of the annular member 15. This effectively prevents excessive rearward movement (especially detachment) of the annular member 15.

[0040] Furthermore, according to the retractable writing instrument 10 of this embodiment, the gripping portion (the smallest inner diameter portion when the diameter is reduced) that grips the tip 14 in the annular member 15 is located in front of the contact surface (first truncated cone outer surface 15b) of the annular member 15 (there is no gripping portion radially inward of the contact surface). As a result, the tip 14 can be gripped further forward, and the tip 14 can be gripped more effectively in a manner that eliminates looseness (play).

[0041] Furthermore, in the retractable writing instrument 10 of this embodiment, the rear end of the slit 15s is located in front of the coil spring 16. This allows for a stable connection between the coil spring 16 and the annular member 15 even when the annular member 15 is bent due to the presence of the slit 15s.

[0042] Furthermore, in the retractable writing instrument 10 of this embodiment, the contact surface of the annular member 15 (the outer surface 15b of the first truncated cone) and the guide surface of the barrel 11 (the inner surface 11ib of the first truncated cone) are always in contact. As a result, the contact surface of the annular member 15 and the guide surface of the barrel 11 do not repeatedly come into contact and separate each time the tip 14 is extended or retracted, resulting in stable operation and a smooth user experience (no sense of discomfort).

[0043] Furthermore, in the retractable writing instrument 10 of this embodiment, the annular member 15 protrudes forward from the opening of the barrel 11. This allows the tip 14 to be gripped over a longer axial range, thus ensuring that the tip 14 is gripped more effectively without any looseness (play). Moreover, it is possible to visually appeal to the user that the retractable writing instrument 10 is equipped with a component (annular member 15) that provides a vibration-reducing effect. In addition, the external shape near the front end of the retractable writing instrument 10 when the tip 14 is protruding can be connected to the pen tip with a smooth shape from the rear, which also has the effect of improving aesthetics.

[0044] Furthermore, in the retractable writing instrument 10 of this embodiment, the amount (length) that the annular member 15 protrudes forward from the opening of the barrel 11 is smaller than the axial range of motion of the annular member 15. As a result, even when the annular member 15 is pushed in so as to be retracted into the opening of the barrel 11, the annular member 15 is still within the axial range of motion, thus effectively preventing the annular member 15 from unintentionally falling off.

[0045] Furthermore, in the retractable writing instrument 10 of this embodiment, it is preferable that a soft material (rubbing material) for a thermochromic writing instrument is provided at the knock operation part for extending and retracting the tip 14, or at the rear of the barrel 11. When the conventional configuration is used in a thermochromic writing instrument, there is a risk that the tip (or tip holder) will become loose due to vibration when rubbing the writing surface, generating noise, but this risk is eliminated with the configuration of this embodiment. Therefore, it is recommended that the configuration of this embodiment also be used in a thermochromic writing instrument. [Prior art documents] [Patent Documents]

[0046] [Patent Document 1] Japanese Utility Model Publication No. 5-85683 [Patent Document 2] Japanese Utility Model Publication No. 5-93884 [Patent Document 3] Japanese Patent Publication No. 2013-220602 [Patent Document 4] Japanese Patent Publication No. 2019-111657 [Patent Document 5] PCT / JP2021 / 046938 (Not published at the time of this application) [Overview of the project] [Problems that the invention aims to solve]

[0047] In the technologies disclosed in Patent Documents 1 and 2, the O-ring can deform radially, resulting in insufficient effectiveness in preventing rattling. Furthermore, the writing tip may catch on the surface of the O-ring, making it difficult to smoothly retract the extended writing tip.

[0048] On the other hand, in the technology disclosed in Patent Document 3, in order to enhance the effect of preventing rattling during writing, it is necessary to appropriately manage the dimensional relationship between the inner surface of the annular member and the outer surface of the writing part. For example, if the gap between the outer surface of the writing part and the inner surface of the annular member is larger than the gap between the outer surface of the writing part and the inner surface of the tip of the barrel, the effect of preventing rattling during writing cannot be obtained. Therefore, high dimensional accuracy is required, which poses a problem in terms of productivity.

[0049] Furthermore, in the first and fourth type configurations of Patent Document 4, two types of coil springs are used in combination, which can cause these coil springs to catch on each other during assembly or refill replacement, impairing the smoothness of the operation. In addition, when the coil springs contract in conjunction with the extension and retraction of the tip holder, these coil springs may become entangled, potentially causing malfunctions (see paragraph 0040 of Patent Document 5, etc.).

[0050] On the other hand, in the second and third type configurations of Patent Document 4, it is difficult to increase the degree of expansion and contraction (bend) of the resin spring part, resulting in a low degree of design freedom (see paragraph 0041 of Patent Document 5, etc.).

[0051] According to the configuration of the first embodiment of Patent Document 5, as described above, with the retractable writing instrument 10 of this embodiment, as the tip holder 13 moves toward the front end, the contact surface of the annular member 15 (first truncated cone outer surface 15b) receives a load from the guide surface of the barrel 11 (first truncated cone inner surface 11ib), causing the inner diameter of the annular member 15 to shrink due to the presence of the slit 15s in the annular member 15. As a result, the barrel 11 and the annular member 15 cooperate to grip the tip 14 without any looseness (play).

[0052] However, in the configuration of the first embodiment of Patent Document 5, even when the tip 14 (cursive) is retracted as shown in Figure 9, the coil spring 16 biases the annular member 15 forward. As a result, the contact surface of the annular member 15 receives a load from the guide surface of the barrel 11, causing the inner diameter of the annular member 15 to shrink (albeit slightly). If this state continues for a long time (if the tip 14 (cursive) is not extended for a long period), the continuous action of the coil spring 16 will cause the shrinkage to exceed the desired value (this is called "creep") (if the tip 14 is extended occasionally, it can be expected that the excessive shrinkage will be reversed as the tip 14 penetrates the annular member 15). If the degree of shrinkage exceeds the desired value, the user may feel an unpleasant resistance when subsequently extending the tip 14.

[0053] More specifically, referring to Figure 10(e), when the tip 14 passes through the connection region (ridge-like boundary) between the small inner diameter cylindrical surface 15ia (φ3.0 mm, axial length 2 mm) of the annular member 15 and the inner surface 15ib of the first truncated cone (φ3.0 mm on the small diameter side, φ3.6 mm on the large diameter side, axial length 0.5 mm), if the degree of diameter reduction of the annular member 15 exceeds the desired value, the user may feel an unpleasant resistance.

[0054] In this regard, in the configuration of the first embodiment of Patent Document 5, the outer surface 15d of the second truncated cone of the annular member 15 and the inner surface 11id of the second truncated cone of the shaft cylinder 11 function as stopper elements that define the limit of the annular member 15's forward movement. However, the inventors of this invention have found that because both the outer surface 15d of the second truncated cone and the inner surface 11id of the second truncated cone are tapered toward the front end, the aforementioned "creep" cannot be sufficiently suppressed.

[0055] This invention has been made in view of the above findings, and its objective is to provide a retractable writing instrument that prevents tip wobble during writing, resulting in a stable writing feel, while minimizing the risk of malfunction and maintaining the smoothness of the tip's protrusion operation for a long period of time. [Means for solving the problem]

[0056] The present invention comprises a shaft cylinder having an opening at its front end; a tip holder housed inside the shaft cylinder and movable in the axial direction of the shaft cylinder; a tip fixed to the front end of the tip holder and movable in and out of the opening of the shaft cylinder as the tip holder moves; an annular member loosely fitted to the inner circumference of the opening of the shaft cylinder and movable in the axial direction of the shaft cylinder; and an elastic member capable of connecting the tip holder and the annular member so as to be able to move relative to each other, wherein at least a portion of the outer circumference of the annular member has a contact surface that abuts against a portion of the inner surface of the shaft cylinder as the tip holder moves toward the front end, and a notch is formed in a portion of the annular member, and the contact surface receives a load. This is a retractable writing instrument characterized by the fact that the inner diameter of the annular member sometimes decreases, a guide surface is formed on a part of the inner surface of the barrel, the contact surface contacts as the tip holder moves toward the front end, the contact surface receives the load from the guide surface as the tip holder moves toward the front end, a raised portion is provided on a part of the inner surface of the barrel, the rear surface of the raised portion has a surface perpendicular to the axial direction or a surface that tapers toward the rear end, and a stopper portion is provided on a part of the outer circumference of the annular member that contacts the raised portion to define the limit of the annular member's forward movement.

[0057] According to the present invention, as the tip holder moves toward the front end, the contact surface of the annular member receives a load from the guide surface of the shaft, causing the inner diameter of the annular member to shrink due to the presence of the notch in the annular member. As a result, the shaft and the annular member cooperate to grip the tip or tip holder without any looseness (play).

[0058] Furthermore, according to the present invention, a stopper portion is provided on a part of the outer circumference of the annular member, which abuts against a raised portion on the inner surface of the shaft cylinder to define the limit of the annular member's forward movement, and the rear surface of the raised portion has a surface perpendicular to the axial direction or a surface that tapers toward the rear end, so that the raised portion can more reliably stop the annular member from moving forward toward the stopper portion. As a result, the aforementioned "creep" can be sufficiently suppressed. This significantly reduces the likelihood that the user will feel an unpleasant resistance when performing the operation to extend the tip.

[0059] Preferably, the raised portion is formed in an annular shape. This makes it possible to more effectively reduce the occurrence of the aforementioned "creep".

[0060] Preferably, the stopper portion is formed as an annular flange portion. This makes it possible to more effectively reduce the occurrence of the aforementioned "creep".

[0061] Furthermore, according to the present invention, since the elastic member can function as a "knock spring," there is no need to use a separate coil spring for the knock spring. As a result, the number of parts is reduced, assembly work is simplified, and the risk of malfunction can be significantly reduced.

[0062] Preferably, the gripping portion for gripping the chip or chip holder in the annular member is located forward of the contact surface of the annular member (there is no gripping portion radially inward of the contact surface). This allows the chip or chip holder to be gripped further forward, and the chip or chip holder can be gripped more effectively without looseness (play).

[0063] Preferably, the notches are arranged at equal intervals in the circumferential direction of the annular member, and each of the multiple notches is a slit extending in the axial direction of the annular member. In this case, the inner diameter of the annular member can be reduced in a well-balanced manner in the circumferential direction.

[0064] Furthermore, in this case, it is even more preferable that the rear end of the slit is located in front of the elastic member. This allows for a stable connection between the elastic member and the annular member even when the annular member is bent due to the presence of the slit.

[0065] The contact surface is preferably tapered toward the front end, and the guide surface is also preferably tapered toward the front end. The contact surface is preferably, for example, a truncated cone. In this case, the guide surface is preferably a corresponding concave truncated cone. Alternatively, the contact surface is preferably a convex surface that is rotationally symmetrical about the axis. In this case, the guide surface is preferably a concave surface or a concave truncated cone that is rotationally symmetrical about the axis and has a curvature gentler than the curvature of the convex surface.

[0066] Preferably, the elastic member is a coil spring.

[0067] Preferably, the annular member and the elastic member are fixed to each other, the elastic member is connectable to the annular collar of the tip holder, and the elastic member is detachable from the annular collar of the tip holder. In this case, since the annular member and the elastic member are held only on the barrel side, existing replacement refills with conventional tip holders can be used.

[0068] Furthermore, preferably, the contact surface and the guide surface are in constant contact. In this case, the annular member and the inner surface of the shaft do not repeatedly come into contact and separate each time the tip is extended or retracted, resulting in stable operation and a smooth user experience (no discomfort).

[0069] Preferably, the annular member protrudes forward from the opening of the shaft cylinder. In this case, the tip or tip holder can be gripped over a longer range, thus ensuring that the tip or tip holder is gripped more effectively without any looseness (play).

[0070] Furthermore, in this case, it is even more preferable that the amount (length) that the annular member protrudes forward from the opening of the shaft cylinder is smaller than the axial range of motion of the annular member. This prevents unwanted detachment of the annular member, etc., because even when the annular member is pushed in so as to be retracted into the opening of the shaft cylinder, the annular member is still within its axial range of motion.

[0071] Preferably, a soft member is provided in the operating section for extending and retracting the tip, or in the rear of the barrel. When the conventional configuration is used in a thermochromic writing instrument, vibrations during writing can cause the tip or tip holder to rattle, potentially generating noise. However, the configuration of the present invention eliminates this risk. Therefore, the configuration of the present invention is also recommended for use in thermochromic writing instruments.

[0072] Preferably, the device further includes a knock member that is slidable in the front-rear direction relative to the barrel, and the tip moves back and forth so as to alternately protrude from and retract from the opening of the barrel each time the knock member is moved forward, and the annular member rotates relative to the barrel each time the knock member is moved forward. As a result, the annular member rotates in conjunction with the forward movement (operation) of the knock member, so the user can visually perceive the rotation of the annular member. This provides the user with a visually interesting experience.

[0073] Furthermore, the present invention also applies only to the barrel of the above-mentioned retractable writing instrument. That is, the present invention relates to a barrel for a retractable writing instrument that is capable of axially movably housing a tip holder on which a tip is fixed at the front end, having an opening at the front end, and capable of extending and retracting the tip from the opening as the tip holder moves, comprising: an annular member loosely fitted to the inner circumference of the opening of the barrel and movable in the axial direction relative to the barrel; an elastic member capable of connecting the tip holder and the annular member so as to be able to move relative to each other; a contact surface formed on at least a part of the outer circumference of the annular member that abuts against a part of the inner surface of the barrel as the tip holder moves toward the front end, and a notch formed on a part of the annular member, when a load is received on the contact surface. The barrel of a retractable writing instrument is characterized in that the inner diameter of the annular member is reduced, a guide surface is formed on a part of the inner surface of the barrel, the contact surface contacts as the tip holder moves toward the front end, the contact surface receives the load from the guide surface as the tip holder moves toward the front end, a raised portion is provided on a part of the inner surface of the barrel that rises toward the central axis of the barrel, the rear surface of the raised portion has a surface perpendicular to the axial direction or a surface that tapers toward the rear end, and a stopper portion is provided on a part of the outer circumference of the annular member that defines the limit of the forward movement of the annular member by contacting the raised portion. [Effects of the Invention]

[0074] According to the present invention, as the tip holder moves toward the front end, the contact surface of the annular member receives a load from the guide surface of the shaft, causing the inner diameter of the annular member to shrink due to the presence of the notch in the annular member. As a result, the shaft and the annular member cooperate to grip the tip or tip holder without any looseness (play). Furthermore, according to the present invention, a stopper portion is provided on a part of the outer circumference of the annular member, which contacts a raised portion on the inner surface of the shaft to define the limit of the annular member's forward movement, and the rear surface of the raised portion has a surface perpendicular to the axial direction or a surface that tapers toward the rear end, so that the raised portion can more reliably stop the annular member from moving toward the stopper portion. As a result, the aforementioned "creep" can be sufficiently suppressed. This significantly reduces the risk of the user feeling an unpleasant resistance when performing the action of extending the tip. In addition, according to the present invention, since the elastic member can function as a "knock spring", there is no need to use a separate coil spring for the knock spring. This can reduce the number of parts, simplify assembly, and significantly reduce the risk of malfunction. [Brief explanation of the drawing]

[0075] [Figure 1] This is a schematic longitudinal cross-sectional view of a retractable writing instrument according to one embodiment of the present invention, showing the state in which the tip (cursive writing instrument) is not protruding. [Figure 2] Figure 2 is a magnified longitudinal cross-sectional view of the tip of the retractable writing instrument shown in Figure 1. [Figure 3] Figure 3(a) is a perspective view of the annular member of the retractable writing instrument shown in Figure 1. Figure 3(b) is a plan view of the annular member shown in Figure 3(a). Figure 3(c) is a side view of the annular member shown in Figure 3(a). Figure 3(d) is a bottom view of the annular member shown in Figure 3(a). Figure 3(e) is a cross-sectional view of the annular member shown along line AA in Figure 3(c). Figure 3(f) is a front view (viewed from the tip side) of the annular member shown in Figure 3(a). Figure 3(g) is a rear view of the annular member shown in Figure 3(a). [Figure 4] Figure 1 is a schematic diagram showing the state in which the tip is in contact with the annular member during the process of extending the tip of the retractable writing instrument. [Figure 5] Figure 1 is a schematic diagram showing the state in which the tip is most protruding during the process of extending the tip in the retractable writing instrument. [Figure 6] Figure 1 is a schematic diagram showing the retractable writing instrument, specifically the state after the tip extension operation has been completed, with the tip extended. [Figure 7] This figure corresponds to Figure 2, showing the state after "creep" has occurred. [Figure 8] This is a schematic longitudinal cross-sectional view of a retractable writing instrument in the first embodiment of Patent Document 5, showing the state in which the tip (writing tip) is not protruding. [Figure 9] Figure 9 is an enlarged longitudinal cross-sectional view of the tip of the retractable writing instrument shown in Figure 8. [Figure 10] Figure 10(a) is a perspective view of the annular member of the retractable writing instrument shown in Figure 1. Figure 10(b) is a plan view of the annular member shown in Figure 10(a). Figure 10(c) is a side view of the annular member shown in Figure 10(a). Figure 10(d) is a bottom view of the annular member shown in Figure 10(a). Figure 10(e) is a cross-sectional view of the annular member shown along line AA in Figure 10(c). Figure 10(f) is a front view (viewed from the tip side) of the annular member shown in Figure 10(a). Figure 10(g) is a rear view of the annular member shown in Figure 10(a). [Figure 11] Figure 8 is a schematic diagram showing the state in which the tip is in contact with the annular member during the process of extending the tip in the retractable writing instrument. [Figure 12] Figure 8 is a schematic diagram showing the state in which the tip is most protruding during the process of extending the tip in the retractable writing instrument. [Figure 13] Figure 8 is a schematic diagram showing the retractable writing instrument, specifically the state after the tip extension operation has been completed, with the tip extended. [Figure 14] This is a vertical cross-section of the refill. [Figure 15] This is a perspective view of the rear end of the refill. [Figure 16] This is a plan view of the rear end of the refill. [Figure 17] This is a longitudinal cross-sectional view of the front shaft of an exemplary shaft cylinder. [Figure 18]This is a longitudinal cross-sectional view of the intermediate shaft of an exemplary shaft cylinder. [Figure 19] This is an example of a longitudinal cross-sectional view of the rear shaft of a shaft cylinder. [Figure 20] This is a longitudinal cross-section of the knocking mechanism. [Figure 21] This is a perspective view of the retractable and rotating member. [Figure 22] This is a front view of the retractable rotating member. [Figure 23] This is a bottom view of the retractable rotating member. [Figure 24] Figure 23 is a cross-sectional view along the CC line. [Figure 25] This is a schematic diagram illustrating the principle of a rotating cam mechanism. [Figure 26] This is a longitudinal cross-sectional view showing the contact state between the retractable rotating member and the rear end of the refill. [Figure 27] This is a perspective view showing the contact state between the retractable rotating member and the rear end of the refill. [Figure 28] This figure corresponds to an enlarged view of Figure 1, and shows a configuration in which the winding direction of the coil spring is reversed. [Figure 29] This figure corresponds to Figure 3(e), and shows an embodiment in which the inner surface of the first truncated cone is replaced by a chamfered portion. [Figure 30] Figure 30(a) is a perspective view of the annular member of a modified retractable writing instrument. Figure 30(b) is a plan view of the annular member of Figure 30(a). Figure 30(c) is a side view of the annular member of Figure 30(a). Figure 30(d) is a bottom view of the annular member of Figure 30(a). Figure 30(e) is a cross-sectional view along line AA of Figure 30(c). Figure 30(f) is a front view (viewed from the tip side) of the annular member of Figure 30(a). Figure 30(g) is a rear view of the annular member of Figure 30(a). [Modes for carrying out the invention]

[0076] One embodiment of the present invention will be described below with reference to the drawings.

[0077] Figure 1 is a schematic longitudinal cross-sectional view of a retractable writing instrument 110 according to one embodiment of the present invention, showing the state in which the tip 114 (cursive writing instrument) is not protruding. Figure 2 is an enlarged longitudinal cross-sectional view of the tip portion of the retractable writing instrument 110 of this embodiment.

[0078] Furthermore, Figure 3(a) is a perspective view of the annular member 115 of the retractable writing instrument 110 of this embodiment, Figure 3(b) is a plan view of the annular member 115 of Figure 3(a), Figure 3(c) is a side view of the annular member 115 of Figure 3(a), Figure 3(d) is a bottom view of the annular member of Figure 3(a), Figure 3(e) is a cross-sectional view of line AA of Figure 3(c), Figure 3(f) is a front view (viewed from the tip side) of the annular member of Figure 3(a), and Figure 3(g) is a rear view of the annular member of Figure 3(a).

[0079] Furthermore, Figure 4 is a schematic diagram showing the state in which the tip 114 is in contact with the annular member 115 during the process of extending the tip 114 in the retractable writing instrument 110 of this embodiment, Figure 5 is a schematic diagram showing the state in which the tip 114 is most extended during the process of extending the tip 114 in the retractable writing instrument 110 of this embodiment, and Figure 6 is a schematic diagram showing the state in which the tip 114 is extended after the extension operation of the tip 114 is completed in the retractable writing instrument 110 of this embodiment.

[0080] The retractable writing instrument 110 of one embodiment shown in Figures 1 to 6 comprises a cylindrical barrel 111 having an opening at its front end. As shown in Figure 1, in this embodiment, the barrel 111 has a rear portion 111r and a front portion 111m. The rear portion 111r and the front portion 111m are detachably fixed by screw connection (screw-in). However, the rear portion 111r and the front portion 111m may be fixed by a fit connection or may be formed integrally.

[0081] Inside the barrel 111 is a tip holder 113 that is movable in the axial direction of the barrel 111. A cursive tip 114 is fixed to the front end of the tip holder 113. As the tip holder 113 moves, the tip 114 can extend and retract from the opening of the barrel 111, as shown in Figures 4 to 6.

[0082] As shown in Figure 2, the tip holder 113 has a base portion 113a, a first collar portion 113b, and a second collar portion 113c in that order from the base end to the tip end. In this embodiment, both the base portion 113a and the first collar portion 113b are cylindrical, and the second collar portion 113c is a truncated cone, and the relationship between their cross-sectional diameters is base portion 113a > first collar portion 113b > second collar portion 113c.

[0083] In this embodiment, as shown in Figure 2, an annular member 115 is loosely fitted to the inner circumference of the opening of the shaft cylinder 111, and is movable in the axial direction of the shaft cylinder 111. The front end of the annular member 115 is located further forward than the front end of the shaft cylinder 111. The rear side of the annular member 115 is enlarged in both its outer and inner diameters, and non-contactly covers the area around the tip 114 (φ2.5).

[0084] Furthermore, the annular member 115 is fixed to the front end of the coil spring 116 (an example of an elastic member). The coil spring 116 loosely surrounds the second collar portion 113c and the tip 114 of the tip holder 113 (with a gap), and the rear end of the coil spring 116 is constantly pressed (not fixed) by the base end portion 113a of the tip holder 113. In this way, the coil spring 116 connects the tip holder 113 and the annular member 115 so that they can move relative to each other. As shown in Figures 4 to 6, the annular member 115 becomes movable in the axial direction of the shaft cylinder 111 as the tip holder 113 moves and the coil spring 116 expands and contracts.

[0085] The annular member 115 is made of resin (e.g., polyacetal, polypropylene, polyethylene) or metal (e.g., brass).

[0086] Furthermore, as shown in Figures 3(a) to 3(g), the outer surface of the annular member 115 has, from the front side, a small outer diameter cylindrical surface 115a (φ3.6 mm, axial length 1.6 mm), a first truncated cone outer surface 115b (axial length 1.1 mm) as a tapered contact surface, a medium outer diameter cylindrical surface 115c (φ4.85 mm, axial length 1.5 mm), a second truncated cone outer surface 115d (axial length 1.6 mm) as a tapered contact surface, and the first The large outer diameter cylindrical surface 115e (φ6.1 mm, axial length 1.2 mm), the annular stepped surface (flange portion) 115f (a surface perpendicular to the axial direction) serving as a stopper, and the second large outer diameter cylindrical surface 115g (φ6.6 mm, axial length 3.3 mm) are provided in this order. The annular stepped surface (flange portion) 115f serving as a stopper may be a surface that is approximately perpendicular to the axial direction (approximately 85° to 95°).

[0087] Furthermore, as shown in Figure 3(e), the inner circumferential surface of the annular member 115 is provided in the following order from the front: a small inner diameter cylindrical surface 115ia (φ3.0 mm, axial length 2 mm), a first truncated cone inner surface 115ib (axial length 0.5 mm), a medium inner diameter cylindrical surface 115ic (φ3.6 mm, axial length 3.9 mm), a second truncated cone inner surface 115id (axial length 0.4 mm), a four-sided blunt section 115ie (inscribed circle φ5.28 mm, axial length 0.9 mm), a large inner diameter cylindrical surface 115if (φ5.43 mm, axial length 2.1 mm), and a third truncated cone inner surface 115ig (axial length 0.4 mm). As shown in Figure 2, in this embodiment, the front end of the coil spring 116 is fixed (fitted and fixed) on the four-sided blunt section 115ie.

[0088] Furthermore, the annular member 115 of this embodiment is provided with three slits 115s as notches. As shown in Figures 3(a) to 3(g), the three slits 115s are arranged at equal intervals (120° apart) in the circumferential direction of the annular member 115. Each of the three slits 115s has a width of 0.8 mm and extends in the axial direction of the annular member 115 from the front end to approximately the center of the outer surface 115d of the second truncated cone (maximum axial length of 5.5 mm).

[0089] As a result, when a load is applied to the outer surface 115b (contact surface) of the first truncated cone, the inner diameter of the annular member 115 flexibly shrinks, and when the load is released, the inner diameter of the annular member 115 elastically returns to its original state.

[0090] On the other hand, as shown in Figures 2, 5, or 6, the inner circumferential surface near the opening of the shaft cylinder 111 consists of, from the front side, a small inner diameter cylindrical surface 111ia (φ3.7 mm, axial length 1.2 mm), a first truncated cone inner surface 111ib (axial length 1.1 mm) serving as a tapered guide surface, a medium inner diameter cylindrical surface 111ic (φ4.95 mm, axial length 1.3 mm), and a second truncated cone inner surface 111id (axial length 1.4 mm) serving as a tapered guide surface. The following are provided in this order: a first large inner diameter cylindrical surface 111ie (φ6.3 mm, axial length 1.4 mm), a circular ring surface 111if (a surface perpendicular to the axial direction) corresponding to the rear surface of the raised portion 111p that rises toward the central axis of the shaft cylinder 111, a second large inner diameter cylindrical surface 111ig (φ6.7 mm, axial length 4.2 mm), and an annular projection 111ih (minimum aperture diameter φ6.5 mm) as a restricting element. The circular ring surface 111if, corresponding to the rear surface of the raised portion 111p that rises toward the central axis of the shaft cylinder 111, only needs to be a surface that is approximately perpendicular to the axial direction (approximately 85° to 95°).

[0091] As a result, the outer surface 1115b (contact surface) of the first truncated cone receives a load from the inner surface 11ib (guide surface) of the first truncated cone as the tip holder 13 moves toward the front end.

[0092] Furthermore, the coil spring 116 in this embodiment also has the function of automatically retracting the tip holder 113 when the tip 114 is retracted (for example, by sliding the operating part provided on the side of the writing instrument to release the locking mechanism that maintains the protruding state of the tip 114). In other words, the coil spring 116 functions as a so-called knock spring. (The operating load is approximately 50gf to 300gf (approximately 0.49N to 2.94N). For example, the operating load from the non-use state (Figure 2) is 68gf, the load at full stroke (Figure 5) is 288gf, and the operating load from the writing state (Figure 6) is 227gf. The spring constant is 0.23N / mm.)

[0093] The retractable writing instrument 110, configured as described above, operates as follows.

[0094] When not in use, the tip 114 (cursive) of the retractable writing instrument 110 is in a retracted state as shown in Figures 1 and 2. Immediately after manufacturing, the axial length of the coil spring 116 is 17 mm (it is a length that has been compressed by about 2 mm beforehand), the annular member 115 has not been reduced in diameter, and the small inner diameter cylindrical surface 115ia of the annular member 115 remains φ3.0 (> outer diameter of the tip 114).

[0095] On the other hand, if the aforementioned "creep" occurs due to a long period of time passing without use after manufacturing, the axial length of the coil spring 116 becomes longer than 17 mm, the annular member 115 has already decreased in diameter, and the small inner diameter cylindrical surface 115ia of the annular member 115 becomes smaller than φ3.0.

[0096] In this embodiment of the retractable writing instrument 110, a flange surface 115f is provided on a part of the outer circumference of the annular member 115, which acts as a stopper portion that defines the limit of forward movement of the annular member 115 by contacting the raised portion 111p on the inner surface of the barrel 111. Furthermore, the circular ring surface 111if, which is the rear surface of the raised portion 111p, is perpendicular to the axial direction. As a result, the raised portion 111p can more reliably stop the forward movement of the annular member 115 (specifically, the flange surface 115f). Consequently, the degree of "creep" can be set to the maximum permissible limit when the flange surface 115f and the circular ring surface 111if are in contact (see Figure 7). This significantly reduces the likelihood of the user experiencing unpleasant resistance when extending the tip. (In the embodiment described in Patent Document 5, the progression of the aforementioned "creep" could not be stopped, and there was a risk that the "creep" would progress to such an extent that the user would feel an unpleasant resistance when extending the tip.)

[0097] According to the findings obtained by the inventors of this invention, in the case of the specifications of the shaft cylinder 111, annular member 115, and coil spring 116 adopted in this embodiment, it is preferable that the position of the coil spring 116 from the position it occupies immediately after manufacturing (see Figure 2) to the position of the coil spring 116 when the flange surface 115f and the circular ring surface 111if are in contact (see Figure 7) be designed to be in the range of approximately 0.2 mm to 1.0 mm.

[0098] Now, when the tip is extended (for example, by sliding the operating part provided on the side of the writing instrument), the tip 114 (cursive writing) of the retractable writing instrument 110 reaches the state shown in Figure 4.

[0099] In the state shown in Figure 4, the protruding operation of the tip 114 moves the second collar portion 113c of the tip holder 113 forward. As a result, the annular member 115 is moved forward on the inner surface of the shaft cylinder 111 via the coil spring 116 and is further pressed against the front of that inner surface, causing the outer surface 115b (contact surface) of the first truncated cone to receive a load from the inner surface 111ib (guide surface) of the first truncated cone, and the presence of the three slits 15s of the annular member 115 causes the inner diameter of the annular member 115 to shrink (if the diameter has already been reduced before the protruding operation of the tip 114 due to the aforementioned "creep", the degree of reduction will be further increased by the protruding operation of the tip 114).

[0100] The inner diameter when the diameter is reduced (in the state shown in Figure 4) is designed to correspond to the outer diameter of the tip 114. That is, this minimum inner diameter when the diameter is reduced (for example, about 2.35 mm to 2.45 mm) is such that it allows for smooth sliding of the tip 114 (for example, φ2.5 mm) in the axial direction, while providing an effective anti-vibration effect for the tip 114 in the radial direction. Furthermore, even if the outer diameter of the tip 114 is smaller (for example, φ2.4 mm) or larger (for example, φ2.6 mm) than the aforementioned φ2.5 mm, the same (same dimensions) annular member 115 can provide a similarly effective anti-vibration effect. In other words, the retractable writing instrument 110 of this embodiment is compatible with different types of refills having different tip outer diameters in terms of anti-vibration effect. This improves user convenience.

[0101] Subsequently, if the tip is extended (for example, by sliding the operating part provided on the side of the writing instrument), the tip 114 (cursive) of the retractable writing instrument 110 will reach the state shown in Figure 5.

[0102] Then, when the tip extension operation is completed (for example, when the sliding operation of the operating part provided on the side of the writing instrument is released), the tip 114 (cursive) of the retractable writing instrument 110 returns to the state shown in Figure 6. Normally, the position of the tip holder 113 is locked in the extended state shown in Figure 6, and the extended state of the tip 114 is maintained until the tip is retracted. At this time, the axial length of the coil spring 116 is 9.9 mm (compressed by 10.1 mm from the state in Figure 2), and the restoring force of the coil spring 116 maintains the annular member 115 in a reduced diameter state. This allows the tip 114 to be gripped without any looseness (play).

[0103] Here, if the dimension of the small inner diameter cylindrical surface 115ia on the inner circumferential surface of the annular member 115 is sufficiently smaller than the outer diameter of the tip 114 (when the diameter difference is about 0.05 mm or more: see paragraph 0100), the tip holder 113 and the annular member 115 are connected by a coil spring 116 so that they can move relative to each other. This ensures that the tip 114 is gripped effectively without any looseness (play) even without high-precision dimensional control regarding the degree of reduction in the inner diameter of the annular member 115.

[0104] Subsequently, when the tip is retracted (for example, by resliding the operating part located on the side of the writing instrument), a locking mechanism (not shown) is released, and the tip 114 (cursive) of the retractable writing instrument 110 returns to the state shown in Figure 5. Furthermore, due to the action of the coil spring 116 (restoring force), it returns to the retracted state shown in Figure 2, via the state shown in Figure 4.

[0105] In the process from the state shown in Figure 4 to the immersed state shown in Figure 2, the tip holder 113 moves to the rear, so the load that the outer surface 115b (contact surface) of the first truncated cone was receiving from the inner surface 111ib (guide surface) of the first truncated cone disappears. Consequently, the inner diameter of the annular member 115, which had been reduced in diameter, returns to its original state (either to the unreduced state or to the reduced diameter state due to creep).

[0106] Furthermore, during the aforementioned process of extending and retracting the tip, the contact surface of the annular member 115 (the outer surface of the first truncated cone 115b) and the guide surface of the shaft cylinder 111 (the inner surface of the first truncated cone 111ib) are always in contact.

[0107] As described above, according to the retractable writing instrument 110 of this embodiment, as the tip holder 113 moves toward the front end, the contact surface of the annular member 115 (the outer surface of the first truncated cone 115b) receives a load from the guide surface of the barrel 111 (the inner surface of the first truncated cone 111ib), causing the inner diameter of the annular member 115 to shrink due to the presence of the slit 115s in the annular member 115. As a result, the barrel 111 and the annular member 115 cooperate to grip the tip 114 without any looseness (play).

[0108] Furthermore, in the retractable writing instrument 110 of this embodiment, a flange surface 115f is provided on a part of the outer circumference of the annular member 115, which acts as a stopper portion that defines the limit of forward movement of the annular member 115 by contacting the raised portion 111p on the inner surface of the barrel 111, and the circular ring surface 111if, which is the rear surface of the raised portion 111p, is a surface perpendicular to the axial direction. As a result, the raised portion 111p can more reliably stop the forward movement of the annular member 115 (flange surface 115f), and as a result, the state in which the flange surface 115f and the circular ring surface 111if contact can be set as the maximum permissible limit for the degree of "creep" (see Figure 7). This significantly reduces the risk of the user feeling an unpleasant resistance when performing the operation of extending the tip.

[0109] In particular, according to the retractable writing instrument 110 of this embodiment, since the raised portion 111p of the barrel 111 (the circular ring surface 111if which is the rear surface of the raised portion) is formed in an annular shape, the occurrence of the aforementioned "creep" can be reduced more effectively. However, at least as of the filing of this application, an embodiment in which the raised portions are discretely arranged in the circumferential direction is also included within the scope of the present invention.

[0110] Furthermore, according to the retractable writing instrument 110 of this embodiment, the flange surface 115f of the annular member 115, which serves as a stopper portion, is formed in an annular shape, which can more effectively reduce the occurrence of the aforementioned "creep." However, at least as of the filing of this application, an embodiment in which the stopper portions are discretely arranged in the circumferential direction is also included within the scope of the present invention.

[0111] Furthermore, according to the retractable writing instrument 110 of this embodiment, since the dimension of the small inner diameter cylindrical surface 115ia on the inner circumferential surface of the annular member 115 is sufficiently smaller than the outer diameter of the tip 114 (the diameter difference is about 0.05 mm or more: see paragraph 0100), and the tip holder 113 and the annular member 115 are connected to each other so as to be able to move relative to each other by the coil spring 116, it is possible to ensure that the tip 114 is gripped effectively without any looseness (play) without requiring high-precision dimensional control regarding the degree of reduction in the inner diameter of the annular member 115.

[0112] Furthermore, according to the retractable writing instrument 110 of this embodiment, the three slits 115s, which serve as notches, are arranged at equal intervals in the circumferential direction of the annular member 115, and each slit 115s extends in the axial direction of the annular member 115, so that the inner diameter of the annular member 115 can be reduced in a well-balanced manner in the circumferential direction.

[0113] Furthermore, since the contact surface of the annular member 115 (first truncated cone outer surface 115b) and the guide surface of the shaft cylinder 111 (first truncated cone inner surface 111ib) are corresponding truncated cone outer and truncated cone inner surfaces, the contact surface of the annular member 115 can receive loads in a balanced manner in the circumferential direction, and as a result, the annular member 115 can be reduced in diameter in a balanced manner in the circumferential direction. In this way, it is preferable that the contact surface of the annular member 115 (first truncated cone outer surface 115b) and the guide surface of the shaft cylinder 111 (first truncated cone inner surface 111ib) are tapered toward the front end. The tapered contact surface has a convex surface that is rotationally symmetric about the axis, and the tapered guide surface may be a concave surface or a concave truncated cone surface that is rotationally symmetric about the axis and has a curvature gentler than the curvature of the convex surface.

[0114] Furthermore, the degree of elasticity (ease of diameter reduction) of the annular member 115 can be adjusted by appropriately changing the number, size, shape, etc. of the slits 115s. In addition, the degree of elasticity (ease of diameter reduction) of the annular member 115 can also be adjusted by changing the material and / or wall thickness of the annular member 115.

[0115] Furthermore, in this embodiment, an annular projection 111ih is provided on the inner circumferential surface of the shaft cylinder 111, defining the rearward limit of movement of the annular member 115. This effectively prevents excessive rearward movement (especially detachment) of the annular member 115.

[0116] Furthermore, according to the retractable writing instrument 110 of this embodiment, the gripping portion (the smallest inner diameter portion when the diameter is reduced) that grips the tip 114 in the annular member 115 is located in front of the contact surface (first truncated cone outer surface 115b) of the annular member 115 (there is no gripping portion radially inward of the contact surface). As a result, the tip 114 can be gripped further forward, and the tip 114 can be gripped more effectively in a manner that eliminates looseness (play).

[0117] Furthermore, in the retractable writing instrument 110 of this embodiment, the rear end of the slit 115s is located in front of the coil spring 116. This allows for a stable connection between the coil spring 116 and the annular member 115 even when the annular member 115 is bent due to the presence of the slit 115s.

[0118] Furthermore, in the retractable writing instrument 110 of this embodiment, the contact surface of the annular member 115 (the outer surface of the first truncated cone 115b) and the guide surface of the barrel 111 (the inner surface of the first truncated cone 111ib) are always in contact. As a result, the contact surface of the annular member 115 and the guide surface of the barrel 111 do not repeatedly come into contact and separate each time the tip 114 is extended or retracted, resulting in stable operation and a smooth user experience (no sense of discomfort).

[0119] Furthermore, in the retractable writing instrument 110 of this embodiment, the annular member 115 protrudes forward from the opening of the barrel 111. This allows the tip 114 to be gripped over a longer axial range, thus ensuring a more effective grip of the tip 114 without any looseness (play). Moreover, it is possible to visually demonstrate to the user that the retractable writing instrument 110 is equipped with a component (annular member 115) that provides a vibration-reducing effect. In addition, the external shape near the front end of the retractable writing instrument 110 when the tip 114 is protruding can be connected to the pen tip with a smooth shape from the rear, thus improving its aesthetic appeal.

[0120] Furthermore, according to the retractable writing instrument 1110 of this embodiment, the amount (length) that the annular member 115 protrudes forward from the opening of the barrel 111 is smaller than the axial range of motion of the annular member 115. As a result, even when the annular member 115 is pushed in so as to be retracted into the opening of the barrel 111, the annular member 115 is still within the axial range of motion, thus effectively preventing the annular member 115 from unintentionally falling off.

[0121] Furthermore, in the retractable writing instrument 110 of this embodiment, it is preferable that a soft material (rubbing material) for a thermochromic writing instrument is provided at the knock operation part for extending and retracting the tip 114, or at the rear of the barrel 111. When the conventional configuration is used in a thermochromic writing instrument, there is a risk that the tip (or tip holder) will become loose due to vibration when rubbing the writing surface, generating noise, but this risk is eliminated with the configuration of this embodiment. Therefore, it is also recommended that the configuration of this embodiment be used in a thermochromic writing instrument.

[0122] (modified version) The rear surface of the raised portion 111p on the inner surface of the shaft cylinder 111 may have a tapered surface toward the rear end. For example, the rear surface of the raised portion 111p on the inner surface of the shaft cylinder 111 may be a truncated cone surface that tapers toward the rear end. The shaft cylinder 111 itself may be processed in this way, or a separate annular spacer member, which has a flat annular front end and such a truncated cone surface at the rear end, may be fixed to the circular ring surface of the shaft cylinder 111 by adhesive or the like.

[0123] In such cases, the stopper portion of the annular member 115 that abuts against it may also be formed in the shape of a concave truncated cone, corresponding to the truncated cone on the rear side of the raised portion 111p. The annular member 115 itself may be processed in this way, or a separate annular spacer member, which has a flat annular shape at the rear end and such a concave truncated cone shape at the front end, may be fixed to the flange surface of the annular member 115 by adhesive or the like.

[0124] (Additional information about refills) The retractable writing instruments 110 and 210 of each of the above embodiments are writing instruments comprising a barrel 111, a refill (cursive writing instrument) housed inside the barrel 111, and a retractable mechanism that allows the tip 114 of the refill to extend and retract freely from the opening of the barrel 111.

[0125] An example of a refill will be explained in detail using Figures 14 to 16. Referring to Figure 14, the refill 6 consists of, for example, a pen tip 61, an ink storage tube 62 into which the pen tip 61 is press-fitted and fixed at the front end opening, thermochromic ink filled in the ink storage tube 62, a follower (e.g., a high-viscosity fluid) filled adjacent to the rear end of the thermochromic ink and which moves forward as the thermochromic ink is consumed, and a tail plug 63 attached to the rear end opening of the ink storage tube 62. The tail plug 63 is provided with an air hole 63a that opens toward the rear end. The air hole 63a allows air to pass between the inside and outside of the ink storage tube 62.

[0126] The pen tip 61 is configured to consist only of a metal ballpoint pen tip that rotatably holds a ball at its front end, or a combination of such a ballpoint pen tip and a synthetic resin pen tip holder that holds the rear outer surface of the ballpoint pen tip. Inside the pen tip 61 is a spring that presses the ball at the front end forward. The spring is configured, for example, as a compression coil spring with a rod portion at its front end, the front end of which is in contact with the rear surface of the ball. When not writing, the forward bias of the spring causes the ball to be in close contact with the inner surface of the inwardly facing front edge of the front end of the ballpoint pen tip. This prevents ink leakage and evaporation from the front end of the pen tip 61.

[0127] (Supplementary information regarding the rear end of the shaft cylinder 111) The shaft cylinder 111 of this embodiment consists of, for example, a tapered cylindrical front shaft 3 (see Figure 17), a cylindrical intermediate shaft 4 (see Figure 18) connected to the rear end of the front shaft 3, and a cylindrical rear shaft 5 (see Figure 19) connected to the rear end of the intermediate shaft 4.

[0128] For example, as shown in Figure 19, a mounting hole 52 may be provided through the rear end of the rear axle 5 in the front-rear direction, and a friction part 53 made of an elastic material may be press-fitted into the mounting hole 52. This allows the friction part 53 to be fixed to the outer surface of the rear end of the rear axle 5. In addition, an inward projection 54 may be integrally formed on the inner surface of the rear axle 5.

[0129] The elastic material constituting the friction portion 53 is preferably an elastic synthetic resin (rubber, elastomer), such as silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin (styrene-ethylene-butylene-styrene copolymer), fluororesin, chloroprene resin, nitrile resin, polyester resin, ethylene propylene diene rubber (EPDM), or a mixture of two or more rubber elastic materials, or a mixture of a rubber elastic material and a synthetic resin.

[0130] The elastic synthetic resin constituting the friction portion 53 is preferably made of a low-wear elastic material that produces almost no wear debris (eraser residue) during friction, rather than a high-wear elastic material (e.g., an eraser). Furthermore, the friction portion 53 can be provided on the outer surface of the rear end of the shaft 111 in various ways. For example, in addition to providing the friction portion 53 made of an elastic material on the outer surface of the rear end of the shaft 111 or the outer surface of the rear end of the rear shaft 5 by press-fitting, engagement, screwing, fitting, bonding, two-color molding, etc., the entire shaft 111 or the entire rear shaft 5 may be integrally formed from an elastic material.

[0131] (Supplementary information regarding knock member 8) Referring to Figure 20, a clip 83 extending in the front-rear direction can be fixed to the knock member 8. A ball portion may be provided protruding from the back surface of the clip 83. The knock member 8 consists of, for example, a base portion 81 to which the rear end of the clip 83 is fixed, and a cylindrical shaft portion 82 integrally connected to the base portion 81 and extending forward from the base portion 81.

[0132] The knock member 8 is obtained, for example, from a molded body of synthetic resin (e.g., polycarbonate resin). The clip 83 is obtained, for example, from a molded body of synthetic resin (e.g., polycarbonate resin) or from a metal material (e.g., stainless steel). The knock member 8 and the clip 83 may be integrally formed from synthetic resin.

[0133] As shown in Figure 20, a cam tooth 82a that engages with the rear end of the projection 71 of the retractable rotating member 7 (see Figures 21 to 24) can be integrally formed at the front end of the shaft portion 82.

[0134] For assembling the knock member 8, the base portion 81 of the knock member 8 is inserted into the first elongated hole 41 of the intermediate shaft 4 from the rear end (open portion) of the first elongated hole 41, and the shaft portion 82 of the knock member 8 is inserted into the intermediate shaft 4. Then, while fitting the inner surface of the rear shaft 5 to the outer surface of the reduced diameter portion of the intermediate shaft 4 so that the first elongated hole 41 of the intermediate shaft 4 and the second elongated hole 51 of the rear shaft 5 communicate radially (overlap in the radial direction), the base portion 81 of the knock member 8 is inserted into the second elongated hole 51 of the rear shaft 5 from the front end (open portion) of the second elongated hole 51. As a result, the intermediate shaft 4 and the rear shaft 5 are connected (the outward projection 44 of the intermediate shaft 4 and the inward projection 54 of the rear shaft 5 overcome each other and engage), and a slide hole 21 extending in the front-rear direction is formed by the first elongated hole 41 and the second elongated hole 51, and the knock member 8 protrudes radially outward from the slide hole 21. The knock member 8 is slidable in the front-rear direction along the slide hole 21.

[0135] The rear shaft 5, to which the friction part 53 is fixed at its rear end, is connected to the rear end of the intermediate shaft 4, so that the friction part 53 is permanently fixed to the rear end of the shaft cylinder 111. Furthermore, since the front shaft 3 and the intermediate shaft 4 are detachably connected by a screw, the refill 6 can be replaced at any time.

[0136] (Supplementary information about the mechanism of appearance) The retractable mechanism of this embodiment is a side-slide type retractable mechanism using a rotating cam mechanism, and consists of the aforementioned knock member 8, a retractable rotating member 7 that moves back and forth to cause the pen tip 61 to protrude or retract from the opening of the barrel 111 each time the knock member 8 is moved forward, and rotates the refill 6 (and therefore the pen tip 61), the aforementioned cam portion 43 provided inside the barrel 111 and capable of engaging or disengaging with the retractable rotating member 7 depending on the position of the knock member 8, and a knock spring 12 (for example, a compression coil spring) provided inside the barrel 111 and biasing the refill 6 backward.

[0137] The pen tip extension and retraction mechanism in this embodiment is a double-knock type in which both the pen tip extension operation and the pen tip retraction operation involve pressing (sliding) the knock member 8 forward.

[0138] (Supplementary information on thermochromic inks) In this embodiment, the thermochromic ink is preferably a reversible thermochromic ink. The reversible thermochromic ink can be configured using various types, either alone or in combination, such as a heat-decolorizing type that decolorizes from a colored state by heating, a color memory-retaining type that alternately stores a colored state or a decolorized state within a specific temperature range, or a heat-developing type that develops color from a decolorized state by heating and returns to a decolorized state by cooling from the colored state.

[0139] As a colorant contained in the reversible thermochromic ink, a reversible thermochromic pigment is preferably used, which is a reversible thermochromic composition containing at least three essential components: (a) an electron-donating color-developing organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the chemical reaction (color reaction) between the two occurs, encapsulated in microcapsules.

[0140] (Supplementary information regarding the rotation of refill 6) As described above, in this embodiment, each time the knocking member 8 is moved forward, the pen tip 61 moves back and forth so as to protrude or retract from the opening of the barrel 111, and the refill 6 (and therefore the pen tip 61) is rotated. Writing instruments in which the pen tip 61 rotates in this manner are popular in the market because they can equalize the wear of the pen tip 61.

[0141] Figure 25 is a schematic diagram illustrating the principle of the rotating cam mechanism. Referring to Figure 25, when the knock member 8 is pushed forward (sliding) against the rearward biasing force of the elastic body (not shown) from the pen tip retracted state (see Figure 25(a)), the protrusion 71 of the retractable rotating member 7, which was engaged with the cam teeth 82a at the front end of the shaft portion 82 of the knock member 8, is pushed forward. The protrusion 71 of the retractable rotating member 7 moves forward along the cam groove 43b.

[0142] As the projection 71 of the retractable rotating member 7 moves forward, the retractable rotating member 7 presses the refill 6 forward through the contact relationship between the contact portion 73 and the projection 63b of the tail cap 63. This causes the pen tip 61 to protrude outward from the opening of the barrel 111.

[0143] At the deepest position of the knocking operation of the knocking member 8, the rear end of the projection 71 moves out of the cam groove 43b of the cam portion 43 and falls into the valley of the cam teeth 82a of the knocking member 8, and consequently the retractable rotating member 7 rotates slightly in the circumferential direction (see Figure 25(b)).

[0144] Subsequently, as the knock member 8 returns to its original position due to the backward biasing force from the spring, the rear end of the protrusion 71 moves to fall into the groove of the cam teeth 43a of the cam portion 43, and the retractable rotating member 7 rotates further in the circumferential direction as a result (see Figure 25(c)). Also, since the rear end of the protrusion 71 remains in the position of the groove of the cam teeth 43a of the cam portion 43, the pen tip is maintained in an extended state.

[0145] Next, when the knocking member 8 is pressed forward (slid) from the pen tip protruding state (see Figure 25c), the rear end of the protrusion 71 of the retractable rotating member 7 is again engaged with the cam teeth 82a at the front end of the shaft portion 82 of the knocking member 8 and pressed forward again.

[0146] At the deepest position of the knocking operation of the knocking member 8, the rear end of the projection 71 moves over the peaks (teeth) of the cam teeth 43a of the cam portion 43 and drops into the valleys of the cam teeth 82a of the knocking member 8, and consequently the retractable rotating member 7 rotates slightly in the circumferential direction (see Figure 25(d)). Subsequently, when the knocking member 8 returns to its original position due to the rearward biasing force of the spring, the projection 71 is introduced into the cam groove 43b, and the pen tip is retracted (see Figure 25(a)).

[0147] Figures 26 and 27 show the contact state between the projection 63b of the tail plug 63 and the contact portion 73 of the retractable rotating member 7.

[0148] The contact portion 73 on the front of the retractable rotating member 7 abuts against the projection 63b of the tail cap 63 at the rear end of the refill 6, and the multiple projections 72 on the front of the retractable rotating member 7 are inserted into the gap 63c between the projections 63b of the tail cap 63 at the rear end of the refill 6, and are engaged in the circumferential direction. As a result, the refill 6 rotates in the circumferential direction as the retractable rotating member 7 rotates in the circumferential direction.

[0149] As described above, in this embodiment, the contact portion 73 on the front of the retractable rotating member 7 rotates the tail plug 63 at the rear end of the refill 6. However, an embodiment in which the retractable rotating member 7 transmits rotational force to other parts of the refill 6 can also be adopted. For example, an embodiment in which there is no tail plug 63 and a plurality of protrusions are integrally formed at the rear end of the refill 6 may be adopted.

[0150] (Supplementary information regarding the rotation of the annular member 115) When the refill 6 is rotated relative to the barrel 111 by the pressing operation of the knocking member 8, the annular member 115 connected to the refill 6 via the coil spring 116 is also rotated relative to the barrel 111.

[0151] At this time, the front end of the coil spring 116 is fixed to the annular member 115. As a result, the front end of the coil spring 116 does not slide on the inner surface of the annular member 115, and there is no risk of the front end damaging the annular member 115. In addition, the annular member 115, which is connected to the refill 6 via the coil spring 116, also rotates relative to the barrel 111, so that the refill 6 and the coil spring 116 can rotate together. As a result, the rear end of the coil spring 116 does not slide on the tip holder 113, and there is no risk of the rear end damaging the tip holder 113. Furthermore, because the refill 6, the annular member 115, and the coil spring 116 rotate together, there is no risk of the smooth rotation of the refill 6 (and consequently the pressing operation of the knock member 8) being hindered. Moreover, since the rotation of the annular member 115 is visible, it can provide the user with visual interest.

[0152] (Rotation direction of refill 6 and winding direction of coil spring 116) In the embodiments described above, the rotation direction of the refill 6, viewed from the rear end, is clockwise, and the winding direction of the coil spring 116 is counterclockwise (a so-called left-handed spring) (extending counterclockwise from the beginning of the winding: see Figure 2).

[0153] However, if the rotation direction of the refill 6 and the winding direction of the coil spring 116 are aligned, when the refill 6 rotates, the tip holder 113 (the part that contacts the coil spring) will be oriented to push the rear end of the coil spring 116 in a certain direction. This makes the connection between the tip holder 113 and the coil spring 116 firm (for example, in a manner in which they catch on each other), which is preferable as it makes it easier for the coil spring 116 to transmit the rotational force of the refill 6 to the annular member 115.

[0154] Figure 28 shows a diagram corresponding to Figure 2, but with the winding direction of the coil spring 116 reversed.

[0155] In this case, it is even more preferable that the coil spring contact portion of the tip holder 113 be provided with an uneven shape or the like to further strengthen the connection with the rear end of the coil spring 116.

[0156] (R chamfering of the inner surface of the annular member 115) As explained with reference to Figure 3(e), the inner circumferential surface of the annular member 115 is provided with the following surfaces in the order shown from the front: a small inner diameter cylindrical surface 115ia, a first truncated cone inner surface 115ib, a medium inner diameter cylindrical surface 115ic, a second truncated cone inner surface 115id, a four-sided blunt portion 115ie, a large inner diameter cylindrical surface 115if, and a third truncated cone inner surface 115ig. Here, an R-chamfer may be provided in the connection region (boundary) between the small inner diameter cylindrical surface 115ia and the first truncated cone inner surface 115ib. In this case, when the tip 114 is inserted into the small inner diameter cylindrical surface 115ia, there is no snagging, so a smoother insertion can be achieved.

[0157] Furthermore, as shown in Figure 29, instead of providing the first truncated cone inner surface 115ib in Figure 3(e), an embodiment may be adopted in which the small inner diameter cylindrical surface 15ia' and the medium inner diameter cylindrical surface 15ic' are connected by the R chamfered portion 15ib' (the first truncated cone inner surface 115ib is replaced by the chamfered portion 15ib'). In this case as well, since there is no snagging when the tip 114 is inserted into the small inner diameter cylindrical surface 15ia', smoother insertion can be achieved. In the modified example shown in Figure 29, the inner circumferential surface of the annular member 15' is provided with, from the front side, a small inner diameter cylindrical surface 15ia', a chamfered portion 15ib', a medium inner diameter cylindrical surface 15ic', a second truncated cone inner surface 15id', a four-sided trimmed portion 15ie', a large inner diameter cylindrical surface 15if', and a third truncated cone inner surface 15ig' in that order. Three slits 15s' are provided as notches.

[0158] (Other forms of notches) In the embodiments described above, a slit 115s was provided as a notch. That is, the notch was formed to penetrate from the inner circumference to the outer circumference of the annular member 115.

[0159] However, the notch is not limited to such a configuration and may be formed as a thin-walled portion compared to the surrounding area (a configuration in which a portion of the thickness is cut out). For example, a configuration in which a thin-walled portion remains in the slit 115s may be adopted.

[0160] Figure 30(a) is a perspective view of such a modified annular member 15”, Figure 30(b) is a plan view of the annular member 15”, Figure 30(c) is a side view of the annular member 15”, Figure 30(d) is a bottom view of the annular member 15”, Figure 30(e) is a cross-sectional view of line AA in Figure 30(c), Figure 30(f) is a front view (viewed from the tip side) of the annular member 15”, Figure 30(g) is a rear view of the annular member 15”, Figure 30(a).

[0161] As shown in Figures 30(a) to 30(g), the outer surface of the annular member 15" is provided in the following order from the front: a small outer diameter cylindrical surface 15a", a first truncated conical outer surface 15b" as a tapered contact surface, a medium outer diameter cylindrical surface 15c", a second truncated conical outer surface 15d" as a tapered contact surface, a first large outer diameter cylindrical surface 15e", a flange surface 15f" as a stopper portion, and a second large outer diameter cylindrical surface 15g".

[0162] Furthermore, the annular member 15" of this modified example is provided with three thin-walled sections 15t" as notches. As shown in Figures 30(a) to 30(g), the three thin-walled sections 15t" are positioned corresponding to the three slits 115s, that is, they are arranged at equal intervals (120° apart) in the circumferential direction of the annular member 15". Each of the three thin-walled sections 15t" has a width of 0.8 mm and a thickness of 0.2 mm, and extends in the axial direction of the annular member 15" from the front end to approximately the center of the outer surface 15d" of the second truncated cone (maximum axial length of 5.5 mm).

[0163] Even with such modifications, when a load is applied to the outer surface 15b" (contact surface) of the first truncated cone, the inner diameter of the annular member 15" can be flexibly reduced, and when the load is released, the inner diameter of the annular member 15" can be elastically returned to its original state. [Explanation of symbols]

[0164] 10 Retractable writing instrument (Patent Document 5) 11 Shaft tube 11ia Small inner diameter cylindrical surface 11ib Inner surface of the first truncated cone 11ic Medium inner diameter cylindrical surface 11id Second truncated cone surface 11ie First large inner diameter cylindrical surface 11if Third truncated cone interior 11ig Second large inner diameter cylindrical surface 11ih annular projection 11m front part 11r rear part 13 Chip holder 13a Proximal end 13b First Color Section 13c Second color section 14 chips 15 Annular member 15a Small outer diameter cylindrical surface 15b Outer surface of the first truncated cone 15c Inner and outer diameter cylindrical surface 15d Outer surface of the second truncated cone 15e First large outer diameter cylindrical surface 15f Third truncated cone outer surface 15g Second largest outer diameter cylindrical surface 15ia Small inner diameter cylindrical surface 15ib Inner surface of the first truncated cone 15ic Medium inner diameter cylindrical surface 15id Second truncated cone inner surface 15ie Four-sided payment section 15if Large inner diameter cylindrical surface 15ig Third truncated cone inner surface 15s Slit 16 Coil springs 110 Retractable writing instrument 111 Shaft cylinder 111ia Small inner diameter cylindrical surface 111ib First truncated cone surface 111ic Medium inner diameter cylindrical surface 111id Second truncated cone inner surface 111ie First large inner diameter cylindrical surface 111if circular ring surface 111ig Second large inner diameter cylindrical surface 111ih Annular protrusion 111m front part 111r rear part 111p Protuberance 113 Chip holder 113a Proximal end 113b First Color Section 113c Second color section 114 chips 115 Annular member 115a Small outer diameter cylindrical surface 115b Outer surface of the first truncated cone 115c Inner and outer diameter cylindrical surface 115d Outer surface of the second truncated cone 115e First large outer diameter cylindrical surface 115f Flange surface (stopper part) 115g Second largest outer diameter cylindrical surface 115ia Small inner diameter cylindrical surface 115ib First truncated cone surface 115ic Medium inner diameter cylindrical surface 115id Second truncated cone surface 115ie Four-sided payment section 115if Large inner diameter cylindrical surface 115ig Third truncated cone inner surface 115s Slit 116 Coil spring 15' Annular member 15ia' Small inner diameter cylindrical surface 15ib' Chamfered section 15ic' Medium inner diameter cylindrical surface 15id' Inner surface of the second truncated cone 15ie' Four-sided payment section 15if' Large inner diameter cylindrical surface 15ig' Third truncated cone surface 15s' Slit 15” annular member 15a” Small outer diameter cylindrical surface 15b” Outer surface of the first truncated cone 15c” inner and outer diameter cylindrical surface 15d” Outer surface of the second truncated cone 15e” First large outer diameter cylindrical surface 15f” Flange surface (stopper section) 15g” Second Large Outer Diameter Cylindrical Surface 15t” Thin-walled section 3 Front axle 32 Main unit 33 Gripping part 4 Intermediate axis 41 First elongated hole 42 Stepped section 43 Cam section 43a Cam teeth 43b Cam groove 44 External process 5 rear axle 51 Second long hole 52 mounting holes 53 Friction part 54 Introvert process 6 Refills (cursive font) 61 nib 62 Ink storage tubes 63. Tail plug 63a Air vent 63b Projection piece 63c gap 63d Small diameter section 63e Large diameter section 63f Tsubabe 63g engaging surface 63p External process 63t auxiliary tapered section 7 Retractable and rotating member 71 protrusion 72 Protrusion 72a Engagement surface 73 Contact part 74 Annular auxiliary projection 74t Auxiliary contact surface 78 External process 8 Knock Member 81 Base 82 Shaft section 82a Cam teeth 83 clips 88 Introvert process

Claims

1. A shaft cylinder having an opening at the front end, A tip holder housed inside the shaft cylinder and movable in the axial direction of the shaft cylinder, A tip fixed to the front end of the tip holder, which can move in and out of the opening of the shaft cylinder as the tip holder moves, An annular member loosely fitted to the inner circumference of the opening of the shaft cylinder and movable in the axial direction relative to the shaft cylinder, An elastic member capable of connecting the chip holder and the annular member so that they can move relative to each other, Equipped with, At least a portion of the outer circumference of the annular member is formed with a contact surface that abuts against a portion of the inner surface of the shaft cylinder as the chip holder moves toward the front end. A notch is formed in a part of the annular member so that the inner diameter of the annular member decreases when a load is applied to the contact surface. A guide surface is formed on a part of the inner surface of the shaft cylinder, which the contact surface contacts as the tip holder moves toward the front end. The contact surface is configured to receive the load from the guide surface as it moves toward the front end of the chip holder. A raised portion is provided on a part of the inner surface of the aforementioned shaft cylinder, which rises toward the central axis of the shaft cylinder. The rear surface of the aforementioned protrusion is either a surface perpendicular to the axial direction, or a surface that tapers towards the rear end. A stopper portion is provided on a part of the outer circumference of the annular member, which contacts the raised portion to define the limit of movement of the annular member on the forward side. A retractable writing instrument characterized by its retractable design.

2. The aforementioned raised portion is formed in an annular shape. The retractable writing instrument according to feature 1.

3. The stopper portion is formed as an annular flange portion. The retractable writing instrument according to feature 1 or 2.

4. Multiple notches are arranged at equal intervals in the circumferential direction of the annular member. Each of the aforementioned multiple notches is a slit extending in the axial direction of the annular member. The retractable writing instrument according to feature 1 or 2.

5. The aforementioned contact surface is tapered towards the front end, The aforementioned guide surface is also tapered towards the front end. The retractable writing instrument according to feature 1 or 2.

6. The aforementioned contact surface has a truncated conical surface. The retractable writing instrument according to feature 5.

7. The elastic member is a coil spring. The retractable writing instrument according to feature 1 or 2.

8. The annular member and the elastic member are fixed to each other. The elastic member is connectable to the annular collar of the chip holder. The elastic member is separable from the annular collar of the chip holder. The retractable writing instrument according to feature 1 or 2.

9. The contact surface and the guide surface are in constant contact. The retractable writing instrument according to feature 1 or 2.

10. The annular member protrudes forward from the opening of the shaft cylinder. The retractable writing instrument according to feature 1 or 2.

11. A soft member is provided at the operating section for extending and retracting the tip, or at the rear of the shaft cylinder. The retractable writing instrument according to feature 1 or 2.

12. A knock member that is slidably mounted in the front-rear direction relative to the shaft cylinder. Furthermore, The tip is configured to move back and forth, alternately protruding from and retracting from the opening of the barrel, each time the knocking member moves forward. The retractable writing instrument according to claim 1 or 2, characterized in that the annular member rotates relative to the barrel each time the knocking member is moved forward.

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