Retractable writing instrument

Abstract

To provide a retractable writing instrument which prevents rattling of a tip in writing and provides stable writing feeling, and is less susceptible to an actuation failure.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 plurality of cutouts are disposed with equal distances therebetween in a circumferential direction of the annular member. The abutment surface is provided such that it protrudes radially outward in each of intermediate positions of two adjacent cutouts in a circumferential direction of the cutouts, as seen from the circumferential direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a retractable writing instrument in which a tip can appear and disappear from an opening in a barrel as a tip holder moves. [Background technology]

[0002] Patent Document 1 discloses a device for preventing the writing tip from shaking. The device is configured by providing a groove at an appropriate position on the writing tip, and fitting an elastic O-ring with an outer diameter approximately equal to the inner diameter of the barrel tip into the groove. This device can prevent rattling noises that occur when the writing tip comes into contact with the tip hole of the barrel tip during writing in pencil-type and knock-type writing implements.

[0003] Patent Document 2 also discloses a device for preventing the writing tip from shaking. This device is configured by engaging an elastic ring with an inner diameter slightly smaller than the outer diameter of the writing tip with a locking step provided inside the tip of the barrel. With this device, the elastic ring locks the writing tip, so even if there is a gap between the inner diameter of the tip of the barrel and the writing tip, it is possible to prevent wobbling during writing.

[0004] Patent Document 3 discloses a writing instrument that slides in the front-rear direction relative to a barrel and delivers a writing part of a writing body from an opening of the barrel. An annular member is disposed on the outer periphery of the tip of the writing body, and a substantially spherical inner surface that the annular member abuts is formed on the inner surface around the opening of the barrel tip from which the writing part appears and disappears. The annular member is fixed to the writing body via a spring and is biased forward. When the writing part is delivered, the annular member is brought into close contact with the inner surface of the barrel tip by the resilience of the spring. This makes it possible to prevent rattling during writing.

[0005] Patent Document 4 by the present applicant discloses four types of configurations of retractable writing implements that prevent tip wobble.

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

[0007] Fig. 13 is a schematic vertical cross-sectional view of the retractable writing instrument 10 in the first embodiment of Patent Document 5, showing a state in which the tip 14 (writing body) is not protruding. Fig. 14 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument 10 in this embodiment.

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

[0009] Furthermore, Figure 16 is a schematic diagram showing the state in which tip 14 comes into contact with annular member 15 during the protruding operation of tip 14 in the retractable writing instrument 10 of this embodiment, Figure 17 is a schematic diagram showing the state in which tip 14 is at its most protruding during the protruding operation of tip 14 in the retractable writing instrument 10 of this embodiment, and Figure 18 is a schematic diagram showing the protruding state of tip 14 after the protruding operation of 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 Fig. 13 to Fig. 18 includes a cylindrical barrel 11 having an opening at the front end. As shown in Fig. 13 to Fig. 15, the barrel 11 in this embodiment has a rear portion 11r and a front portion 11m. The rear portion 11r and the front portion 11m are removably fixed by a screw connection (screwed engagement). However, the rear portion 11r and the front portion 11m may be fixed by a fitting connection, or may be formed integrally.

[0011] A tip holder 13 that is movable in the axial direction of the barrel 11 is housed inside the barrel 11. A tip 14, which is a writing body, is fixed to the front end of the tip holder 13. The tip 14 can appear and disappear from the opening of the barrel 11 as the tip holder 13 moves, as shown in Figures 16 to 18.

[0012] 14, the tip holder 13 has, in this order from the base end side to the tip end side, a base end portion 13a, a first collar portion 13b, and a second collar portion 13c. In this embodiment, the base end portion 13a and the first collar portion 13b are both cylindrical portions, and the second collar portion 13c is a truncated cone portion in this embodiment, and the relationship between their cross-sectional diameters is base end portion 13a>first collar portion 13b>second collar portion 13c.

[0013] In this embodiment, as shown in Fig. 14, an annular member 15 that is movable in the axial direction of the barrel 11 relative to the barrel 11 is loosely fitted around the inner periphery of the opening of the barrel 11. The front end of the annular member 15 is located forward of the front end of the barrel 11. The rear side of the annular member 15 has an expanded outer diameter and inner diameter, and covers the periphery of the tip 14 (φ2.5) without contacting it.

[0014] The annular member 15 is fixed to the front end of a coil spring 16 (an example of an elastic member). The coil spring 16 surrounds the second collar portion 13c of the tip holder 13 and the tip 14 in a loosely fitted state (with a gap), and the rear end of the coil spring 16 is constantly pressed by the base end portion 13a of the tip holder 13 (not fixed). As a result, 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 16 to 18, the annular member 15 can move in the axial direction of the shaft tube 11 with respect to the shaft tube 11 as the tip holder 13 moves and the coil spring 16 expands and contracts.

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

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

[0017] 15(e), the inner peripheral surface of the annular member 15 is provided with 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 sweep portion 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) in this order from the front side. As shown in FIG. 14, in this embodiment, the front end of the coil spring 16 is fixed (fitted) onto the four-sided sweep portion 15ie.

[0018] Furthermore, the annular member 15 of this embodiment is provided with three slits 15s as cutouts. As shown in Fig. 15(a) to Fig. 15(g), the three slits 15s are arranged at equal intervals (every 120°) in the circumferential direction of the annular member 15. Furthermore, 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 second truncated cone outer surface 15d (maximum axial length: 5.5 mm).

[0019] As a result, when a load is applied to the first truncated cone outer surface 15b (contact surface), 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 14, 17 and 18, the inner surface near the opening of the barrel 11 is provided with, in that order from the front side, a small inner diameter cylindrical surface 11ia (φ3.7 mm, axial length 1.2 mm), a first truncated conical 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 conical 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 conical 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 protrusion 11ih (minimum aperture diameter φ6.5 mm) as a regulating element.

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

[0022] The coil spring 16 of this embodiment also has the function of automatically retracting the tip holder 13 when the tip 14 is retracted (for example, by sliding an operating part provided on the side of the writing instrument to release a locking mechanism that maintains the tip 14 in a protruding state). That is, the coil spring 16 functions as a so-called knock spring. (The operating load is about 50gf to 300gf (about 0.49N to 2.94N). For example, the operating load when not in use (FIG. 14) is 68gf, the load at full stroke (FIG. 17) is 288gf, and the operating load when writing (FIG. 18) is 227gf. The spring constant is 0.23N / mm.)

[0023] The retractable writing instrument 10 configured as above operates as follows.

[0024] When not in use, the tip 14 (writing body) of the retractable writing instrument 10 is in a retracted state as shown in Figures 13 and 14. At this time, the axial length of the coil spring 16 is 17 mm, the annular member 15 is not contracted, and the small inner diameter cylindrical surface 15ia of the annular member 15 remains at φ3.0 (>outer diameter of the tip 14).

[0025] When a tip protruding operation (for example, a sliding operation of an operating portion provided on the side surface of the writing instrument) is performed, the tip 14 (writing body) of the retractable writing instrument 10 reaches the state shown in FIG.

[0026] 16, the second collar portion 13c of the tip holder 13 is moved forward by the protruding operation of the tip 14. As a result, the annular member 15 is moved to the front side of the inner surface of the barrel 11 via the coil spring 16 and is further pressed against the front side of the inner surface, so that the first truncated cone outer surface 15b (contact surface) receives a load from the first truncated cone inner surface 11ib (guide surface), and the inner diameter of the annular member 15 is reduced due to the presence of the three slits 15s in the annular member 15.

[0027] The inner diameter when the diameter is reduced corresponds to the outer diameter of the tip 14. That is, the minimum inner diameter when the diameter is reduced (for example, about 2.35 mm to 2.45 mm) allows the tip 14 (for example, φ2.5 mm) to slide smoothly in the axial direction, while the dimension is set to provide an effective anti-vibration effect for the tip 14 in the radial direction. Also, 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 above-mentioned φ2.5 mm, the same (same dimensions) annular member 15 can provide a similarly effective anti-vibration effect. That is, the retractable writing instrument 10 of this embodiment is compatible with different types of refills having different tip outer diameters in terms of the anti-vibration effect. This can improve the convenience of the user.

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

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

[0030] Then, when the tip protruding operation is completed (for example, the sliding operation of the operating part provided on the side of the writing instrument is released), the tip 14 (writing body) of the retractable writing instrument 10 reaches the state shown in FIG. 18. Normally, the position of the tip holder 13 is locked in the protruding state of FIG. 18, and the protruding state of the tip 14 is maintained until the tip is subsequently retracted. At this time, the axial length of the coil spring 16 is 9.9 mm (compressed by 10.1 mm), and the restoring force of the coil spring 16 maintains the annular member 15 in a contracted state. This allows the tip 14 to be held without any rattling (play).

[0031] Here, even if the stopper element that determines the forward movement limit of the annular member 15 functions, if the dimension of the small inner diameter cylindrical surface 15ia on the inner surface of the annular member 15 is sufficiently smaller than the outer diameter of the tip 14 (if the diameter difference is about 0.05 mm or more: see paragraph 0110), the tip holder 13 and the annular member 15 are connected to each other by the coil spring 16 so that they can move relative to each other, so that it is guaranteed that the tip 14 will be effectively gripped without any rattling (play) without high-precision dimensional control over the degree of reduction in the inner diameter of the annular member 15, etc.

[0032] Thereafter, when the tip is retracted (for example, by re-sliding the operating part provided on the side of the writing instrument), for example, a locking mechanism (not shown) is released, and the tip 14 (writing body) of the retractable writing instrument 10 returns to the state shown in Figure 17, and then, due to the action (restoring force) of the coil spring 16, it returns to the retracted state shown in Figure 14 via the state shown in Figure 16.

[0033] 14 from the state in Fig. 16, the tip holder 13 is moved backward, and the load that the first truncated cone outer surface 15b (contact surface) received from the first truncated cone inner surface 11ib (guide surface) disappears. Accordingly, the inner diameter of the annular member 15, which had been reduced, returns to its original state.

[0034] During the above-described process of the tip extension and retraction operation, the contact surface of the annular member 15 (first truncated cone outer surface 15b) and the guide surface of the barrel 11 (first truncated cone inner surface 11ib) are always in contact with each other.

[0035] As described above, according to the retractable writing instrument 10 of this embodiment, as the tip holder 13 moves toward the front end side, the contact surface (first truncated cone outer surface 15b) of the annular member 15 receives a load from the guide surface (first truncated cone inner surface 11ib) of the barrel 11, and the presence of the slits 15s in the annular member 15 reduces the inner diameter of the annular member 15. This allows the barrel 11 and the annular member 15 to cooperate to hold the tip 14 without any rattling (play). Furthermore, according to the retractable writing instrument 10 of this embodiment, a stopper element functions to determine the limit of forward movement of the annular member 15, but since the dimension of the small inner diameter cylindrical surface 15ia on the inner 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 0110), and the tip holder 13 and the annular member 15 are connected to each other by the coil spring 16 so that they can move relative to each other, it is guaranteed that the tip 14 will be effectively held without any rattling (play) even without high-precision dimensional control over the degree of reduction in the inner diameter of the annular member 15, etc.

[0036] In addition, according to the retractable writing instrument 10 of this embodiment, three slits 15s as notches are arranged at equal intervals around the circumference 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 balanced manner around the circumference.

[0037] In addition, since the contact surface (first truncated cone outer surface 15b) of the annular member 15 and the guide surface (first truncated cone inner surface 11ib) of the barrel 11 are the corresponding truncated cone outer surface and truncated cone inner surface, the contact surface of the annular member 15 can receive a load in a circumferentially balanced manner, and as a result, the diameter of the annular member 15 can be reduced in a circumferentially balanced manner. In this manner, it is preferable that the contact surface (first truncated cone outer surface 15b) of the annular member 15 and the guide surface (first truncated cone inner surface 11ib) of the barrel 11 are tapered toward their front ends. The tapered contact surface has a convex curved surface that is rotationally symmetric about the axis, and the tapered guide surface may be a concave curved surface or a concave truncated cone surface that is rotationally symmetric about the axis and has a curvature that is gentler than that of the convex curved surface.

[0038] In addition, by appropriately changing the number, size, shape, etc. of the slits 15s, it is possible to adjust the degree of elasticity (ease of diameter reduction) of the annular member 15. In addition, by changing the material and / or thickness of the annular member 15, it is possible to adjust the degree of elasticity (ease of diameter reduction) of the annular member 15.

[0039] In this embodiment, an annular protrusion 11ih is provided on the inner peripheral surface of the barrel 11, and defines the rearward movement limit of the annular member 15. This effectively prevents the annular member 15 from excessively moving rearward (especially from falling off).

[0040] Furthermore, according to the retractable writing instrument 10 of this embodiment, the gripping portion (portion with the smallest inner diameter when the diameter is reduced) of the annular member 15 that grips the tip 14 is located forward 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). This allows the tip 14 to be gripped further forward, and the tip 14 can be gripped more effectively without rattling (play).

[0041] Furthermore, according to the retractable writing instrument 10 of this embodiment, the rear end of the slit 15s is located forward of the coil spring 16. This makes it possible to maintain 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, according to the retractable writing instrument 10 of this embodiment, the contact surface (first truncated cone outer surface 15b) of the annular member 15 and the guide surface (first truncated cone inner surface 11ib) of the barrel 11 are always in contact with each other. This prevents the contact surface of the annular member 15 and the guide surface of the barrel 11 from repeatedly coming into contact with each other and separating from each other every time the tip 14 is retracted, resulting in stable operation and a smooth operation feeling for the user (no discomfort).

[0043] In addition, according to 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 held over a longer axial range, ensuring that the tip 14 is held more effectively without any wobble (play). Furthermore, the fact that the retractable writing instrument 10 is equipped with a component (annular member 15) that acts to prevent vibration can be visually appealed to the user. Furthermore, the external appearance of the retractable writing instrument 10 near the front end with the tip 14 protruding can be smoothly connected from the rear to the pen tip, which also has the effect of improving the aesthetic appearance.

[0044] Furthermore, according to the retractable writing instrument 10 of this embodiment, the amount (length) by which the annular member 15 protrudes forward from the opening of the barrel 11 is smaller than the axial movable range of the annular member 15. As a result, even when the annular member 15 is pushed in so as to be immersed in the opening of the barrel 11, the annular member 15 is still within the axial movable range, so that the annular member 15 can be effectively prevented from undesirably falling off, etc.

[0045] In addition, in the retractable writing instrument 10 of this embodiment, it is preferable that a soft member (abrasion member) for a thermochromic writing instrument is provided at the knock operation portion for the retraction operation of the tip 14 or at the rear of the barrel 11. When a conventional configuration is adopted for a thermochromic writing instrument, there is a risk that the tip (or tip holder) will rattle due to vibration during rubbing of writing, which may cause noise, but there is no such risk with the configuration of this embodiment. Therefore, it is also recommended to adopt the configuration of this embodiment for a thermochromic writing instrument. [Prior art documents] [Patent documents]

[0046] [Patent Document 1] Application Publication No. 5-85683 [Patent Document 2] Application Publication No. 5-93884 [Patent Document 3] Patent Publication No. 2013-220602 [Patent Document 4] Patent Publication 2019-111657 [Patent Document 5] PCT / JP2021 / 046938 (unpublished at the time of filing this application) Summary of the Invention [Problem to be solved by the invention]

[0047] The techniques disclosed in Patent Documents 1 and 2 are insufficient in preventing rattling because the O-ring can deform in the radial direction. Also, the writing part can get stuck on the surface of the O-ring, making it difficult to smoothly retract the extended writing part.

[0048] On the other hand, in the technology disclosed in Patent Document 3, in order to enhance the effect of preventing wobbling during writing, it is necessary to properly manage the dimensional relationship between the inner surface of the annular member and the outer peripheral surface of the writing part. For example, if the gap dimension between the outer peripheral surface of the writing part and the inner surface of the annular member is larger than the gap dimension between the outer peripheral surface of the writing part and the inner surface of the tip of the barrel, the effect of preventing wobbling during writing cannot be obtained. For this reason, high dimensional accuracy is required, which causes problems in terms of productivity.

[0049] In addition, in the first and fourth types of configurations of Patent Document 4, two types of coil springs are used in combination, and these coil springs may get caught on each other during assembly or refill replacement, which may impair the smoothness of the work. Furthermore, when the coil springs contract as the tip holder extends and retracts, these coil springs may get tangled and cause 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 (deflection amount) of the resin spring portion, so the degree of design freedom is low (see paragraph 0041 of Patent Document 5, etc.).

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

[0052] However, in the configuration of the first embodiment of Patent Document 5, if the circularity of the cross section of the barrel 11 is distorted, the contact state between the contact surface (first truncated cone outer surface 15b) of the annular member 15 and the guide surface (first truncated cone inner surface 11ib) of the barrel 11 does not become the desired surface contact state, but becomes a biased local line contact state (see FIG. 4(b)), and the annular member 15, which receives a load through such a contact state, may not shrink in diameter in the central axis direction of the tip with good precision (while maintaining circularity). In such a case, the gripping force of the tip 14 may become insufficient, or even the unbalanced gripping force may act to bend the tip 14.

[0053] Also, even in the retracted state of the tip 14 (writing body) as shown in FIG. 14, the coil spring 16 biases the annular member 15 forward. Therefore, the contact surface of the annular member 15 receives a load from the guide surface of the shaft tube 11, and the inner diameter of the annular member 15 is in a state of being (albeit slightly) contracted. If such a state continues for a long time (if the period during which the tip 14 (writing body) is not protruded is long), the continuous action of the coil spring 16 will cause the diameter to be reduced to a degree that exceeds a desired value (called "creep"). (If the tip 14 is protruded from time to time, it can be expected that the tip 14 will penetrate the annular member 15 and return to the original excessively contracted state.) If the degree of diameter reduction exceeds the desired value, there is a risk that the user will feel an unpleasant sense of resistance when performing the action of protruding the tip 14 thereafter. Considering this problem, it is difficult to design the biasing force of the coil spring 16 to be too large.

[0054] The present invention has been made in consideration of the above-mentioned findings, and its object is to provide a retractable writing instrument which prevents the tip from rattling when writing, providing a stable writing feel, while also reducing the risk of malfunction. [Means for solving the problem]

[0055] The present invention comprises a barrel having an opening at a front end, a chip holder accommodated inside the barrel and movable in the axial direction of the barrel, a chip fixed to the front end of the chip holder and movable in and out of the opening of the barrel as the chip holder moves, an annular member loosely fitted into the inner periphery of the opening of the barrel and movable in the axial direction of the barrel relative to the barrel, and an elastic member capable of connecting the chip holder and the annular member so as to be movable relative to each other, wherein at least a portion of the outer periphery of the annular member is formed with an abutment surface which abuts against a portion of the inner surface of the barrel as the chip holder moves towards the front end, and a cut-out is provided on a portion of the annular member. This retractable writing instrument is characterized in that a notch is formed in the annular member so that the inner diameter of the annular member reduces when a load is received at the abutment surface, a guide surface is formed on a part of the inner surface of the barrel against which the abutment surface abuts as the tip holder moves toward the front end, and the abutment surface receives the load from the guide surface as the tip holder moves toward the front end, multiple notches are arranged at equal intervals around the circumference of the annular member, and the abutment surface is provided so as to protrude radially outward at each of the intermediate positions between two circumferentially adjacent notches of the multiple notches when viewed in the circumferential direction.

[0056] According to the present invention, as the tip holder moves toward the front end side, the contact surface of the annular member receives a load from the guide surface of the barrel, and the presence of the notch in the annular member reduces the inner diameter of the annular member, allowing the barrel and the annular member to cooperate to grip the tip or tip holder without rattling (play).

[0057] Furthermore, according to the present invention, the contact surface of the annular member is provided so as to protrude radially outward at each of the intermediate positions between two circumferentially adjacent notches of the plurality of notches when viewed in the circumferential direction, so that even if the roundness of the cross section of the barrel is distorted, the annular member can be reduced in diameter in the central axis direction of the tip with relatively high precision (while maintaining roundness) (see FIG. 3(b)). This further reduces the risk of malfunction.

[0058] Preferably, the contact surface is formed in the shape of a rib extending in the axial direction of the annular member, so that the contact surface of such an annular member can bear the load from the guide surface of the barrel in a more balanced manner.

[0059] The present invention comprises a barrel having an opening at a front end, a chip holder accommodated inside the barrel and movable in the axial direction of the barrel, a chip fixed to the front end of the chip holder and movable in and out of the opening of the barrel as the chip holder moves, an annular member loosely fitted into the inner periphery of the opening of the barrel and movable in the axial direction of the barrel relative to the barrel, and an elastic member capable of connecting the chip holder and the annular member so as to be movable relative to each other, wherein at least a portion of the outer periphery of the annular member is formed with an abutment surface that abuts against a portion of the inner surface of the barrel as the chip holder moves towards the front end, and a notch is formed in a portion of the annular member. a retractable writing instrument having an annular member configured to reduce its inner diameter when a load is applied to the abutment surface, a guide surface against which the abutment surface abuts as the tip holder moves toward the front end, and the abutment surface receives the load from the guide surface as the tip holder moves toward the front end, a plurality of the notches are arranged at equal intervals around the circumference of the annular member, and the inner surface of the annular member is provided with a raised portion that protrudes radially inward at each of the intermediate positions between two circumferentially adjacent notches of the plurality of notches when viewed in the circumferential direction.

[0060] According to the present invention, when the tip holder moves toward the front end side, the contact surface of the annular member receives a load from the guide surface of the barrel, and the presence of the notch in the annular member reduces the inner diameter of the annular member, so that the barrel and the annular member cooperate to hold the tip or tip holder without rattling (play).

[0061] Furthermore, according to the present invention, the inner peripheral surface of the annular member is provided with a protruding portion that protrudes radially inward at each intermediate position between two circumferentially adjacent notches of the plurality of notches when viewed in the circumferential direction, so that even if the roundness of the cross section of the barrel is distorted, the annular member can apply a gripping force relatively accurately in the central axis direction of the tip (see FIG. 7(b)). This further reduces the risk of malfunction.

[0062] Preferably, the raised portion is formed as a rib extending in the axial direction of the annular member, which can provide a more balanced gripping force in the axial direction of the tip.

[0063] It is also preferable to adopt an embodiment that simultaneously has both the following features: the abutment surface is provided so as to protrude radially outward at each of the intermediate positions between two circumferentially adjacent notches of the plurality of notches when viewed in the circumferential direction; and the inner surface of the annular member is provided with a protruding portion that protrudes radially inward at each of the intermediate positions between two circumferentially adjacent notches of the plurality of notches when viewed in the circumferential direction.

[0064] In this case, even if the roundness of the cross section of the barrel is distorted, the annular member can reduce its diameter in the central axis direction of the tip with relatively high precision (while maintaining its roundness), and the annular member can apply a gripping force in the central axis direction of the tip with relatively high precision (see FIG. 9(b)). This further reduces the risk of malfunction.

[0065] The present invention comprises a barrel having an opening at a front end, a chip holder accommodated inside the barrel and movable in the axial direction of the barrel, a chip fixed to the front end of the chip holder and movable in and out of the opening of the barrel as the chip holder moves, an annular member loosely fitted into the inner periphery of the opening of the barrel and movable in the axial direction of the barrel relative to the barrel, and an elastic member capable of connecting the chip holder and the annular member so as to be movable relative to each other, wherein at least a portion of the outer periphery of the annular member is formed with an abutment surface which abuts against a portion of the inner surface of the barrel as the chip holder moves towards the front end, and a cut-out is provided on a portion of the annular member. This retractable writing instrument is characterized in that a notch is formed in the annular member so that the inner diameter of the annular member reduces when a load is received at the abutment surface, a guide surface is formed on a part of the inner surface of the barrel against which the abutment surface abuts as the tip holder moves toward the front end, and the abutment surface receives the load from the guide surface as the tip holder moves toward the front end, multiple notches are arranged at equal intervals around the circumference of the annular member, and the guide surface is provided so as to protrude radially inward at each of the intermediate positions between two circumferentially adjacent notches of the multiple notches when viewed in the circumferential direction.

[0066] According to the present invention, when the tip holder moves toward the front end side, the contact surface of the annular member receives a load from the guide surface of the barrel, and the presence of the notch in the annular member reduces the inner diameter of the annular member, so that the barrel and the annular member cooperate to hold the tip or tip holder without rattling (play).

[0067] Furthermore, according to the present invention, the guide surface of the barrel is provided so as to protrude radially inward at each intermediate position between two circumferentially adjacent notches of the plurality of notches when viewed in the circumferential direction, so that even if the roundness of the cross section of the barrel is distorted, the annular member can be reduced in diameter in the central axis direction of the tip with relatively high precision (while maintaining roundness) (see Figs. 11(b) and 12(b)). This further reduces the risk of malfunction.

[0068] 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. This reduces the number of parts, simplifies assembly work, and significantly reduces the risk of malfunction.

[0069] Preferably, the gripping portion of the annular member that grips the tip or tip holder is located forward of the abutment surface of the annular member (there is no gripping portion radially inward of the abutment surface), which allows the tip or tip holder to be gripped further forward and more effectively gripped without rattling (play).

[0070] Preferably, the shaft tube and / or the annular member is provided with a stopper element that defines a rearward movement limit of the annular member, which can effectively prevent excessive movement (especially falling off) of the annular member.

[0071] Preferably, each of the plurality of cutouts is a slit extending in the axial direction of the annular member, in which case the inner diameter of the annular member can be reduced in a well-balanced manner in the circumferential direction.

[0072] In this case, it is further preferable that the rear end of the slit is located forward of the elastic member, so that a stable connection between the elastic member and the annular member can be maintained even when the annular member is bent due to the presence of the slit.

[0073] The abutment surface is preferably tapered toward the front end, and the guide surface is preferably also tapered toward the front end. The abutment surface preferably has, for example, a truncated conical surface. In this case, the guide surface is preferably a corresponding concave truncated conical surface. Alternatively, the abutment surface preferably has a convex curved surface that is rotationally symmetric about an axis. In this case, the guide surface is preferably a concave curved surface or a concave truncated conical surface that is rotationally symmetric about an axis and has a curvature that is gentler than the curvature of the convex curved surface.

[0074] Also, preferably, the elastic member is a coil spring.

[0075] In addition, 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 separable 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, it is possible to use an existing replacement refill having a conventional tip holder.

[0076] Preferably, the contact surface and the guide surface are in constant contact with each other. In this case, the annular member and the inner surface of the barrel do not repeatedly come into contact with and separate from each other every time the tip is extended or retracted, so that the operation is stable and the user feels smooth (no discomfort).

[0077] Preferably, the annular member protrudes forward from the opening of the barrel, which allows the tip or tip holder to be gripped over a longer range, ensuring more effective gripping of the tip or tip holder without rattle (play).

[0078] In this case, it is further preferable that the amount (length) by which the annular member protrudes forward from the opening of the barrel is smaller than the axial movable range of the annular member. In this way, even when the annular member is pushed into the opening of the barrel, the annular member is still within the axial movable range, so that undesired detachment of the annular member can be prevented.

[0079] In addition, preferably, a soft member is provided at the operating part for operating the tip to extend and retract, or at the rear of the barrel. When the conventional configuration is adopted for a thermochromic writing instrument, there is a risk that the tip or tip holder will rattle due to vibration during writing and generate noise, but the configuration of the present invention does not have such a risk. Therefore, it is also recommended to adopt the configuration of the present invention for a thermochromic writing instrument.

[0080] Also, preferably, the device further includes a knock member that is slidable in the front-rear direction relative to the barrel, and the tip is moved forward and backward so as to alternately protrude and retract from the opening of the barrel each time the knock member is moved forward, and the annular member is rotated relative to the barrel each time the knock member is moved forward. In this way, the annular member rotates with the forward movement (operation) of the knock member, so that the user can visually recognize the rotation of the annular member. This can provide visual interest to the user.

[0081] The present invention also covers only the barrel of the retractable writing instrument. That is, the present invention is a barrel for a retractable writing instrument that can accommodate a tip holder with a tip fixed to its front end so as to be movable in the axial direction, has an opening at its front end, and can cause the tip to protrude and retract from the opening as the tip holder moves, and includes an annular member that is loosely fitted into the inner circumference of the opening of the barrel and is movable in the axial direction of the barrel relative to the barrel, an elastic member that can connect the tip holder and the annular member so as to be movable relative to each other, and an abutment surface is formed on at least a portion of the outer circumference of the annular member that abuts against a portion of the inner surface of the barrel as the tip holder moves toward the front end, and a notch is formed in a portion of the annular member. a guide surface is formed on a portion of the inner surface of the barrel against which the abutment surface abuts as the tip holder moves toward the front end, and the abutment surface receives the load from the guide surface as the tip holder moves toward the front end; a plurality of the notches are arranged at equal intervals around the circumference of the annular member, and the abutment surface is provided so as to protrude radially outward at each of the intermediate positions between two circumferentially adjacent notches of the plurality of notches when viewed in the circumferential direction. This is a barrel for a retractable writing instrument, characterized in that

[0082] Alternatively, the present invention relates to a barrel for a retractable writing instrument capable of axially movably housing a tip holder having a tip fixed to a front end, the barrel having an opening at the front end, and capable of causing the tip to protrude and retract from the opening as the tip holder moves, the barrel comprising: an annular member loosely fitted into the inner periphery of the opening of the barrel and movable in the axial direction of the barrel relative to the barrel; an elastic member capable of connecting the tip holder and the annular member so as to be movable relative to each other; and an abutment surface formed on at least a portion of the outer periphery of the annular member that abuts against a portion of the inner surface of the barrel as the tip holder moves towards the front end, and a notch formed in a portion of the annular member. a barrel for a retractable writing instrument, characterized in that the inner diameter of the annular member is reduced when a load is received at the abutment surface, a guide surface is formed on a part of the inner surface of the barrel against which the abutment surface abuts as the tip holder moves toward the front end, and the abutment surface receives the load from the guide surface as the tip holder moves toward the front end, the notches are arranged at equal intervals around the circumference of the annular member, and the inner surface of the annular member has a raised portion that protrudes radially inward at each of the intermediate positions between two circumferentially adjacent notches of the plurality of notches when viewed in the circumferential direction.

[0083] Alternatively, the present invention is also directed to only the barrel of the retractable writing instrument. That is, the present invention is a barrel for a retractable writing instrument capable of axially movably housing a tip holder having a tip fixed to a front end, having an opening at the front end, and capable of causing the tip to protrude and retract from the opening as the tip holder moves, comprising: an annular member loosely fitted in the inner circumference of the opening of the barrel and movable in the axial direction of the barrel relative to the barrel; an elastic member capable of connecting the tip holder and the annular member so as to be movable relative to each other; and an abutment surface formed on at least a portion of the outer circumference of the annular member that abuts against a portion of the inner surface of the barrel as the tip holder moves toward the front end, and a notch formed in a portion of the annular member. a guide surface is formed on a part of the inner surface of the barrel against which the abutment surface abuts as the tip holder moves toward the front end, and the abutment surface receives the load from the guide surface as the tip holder moves toward the front end; a plurality of the notches are arranged at equal intervals around the circumference of the annular member, and the guide surface is provided so as to protrude radially inward at each of the intermediate positions between two circumferentially adjacent notches of the plurality of notches when viewed in the circumferential direction. This is a barrel for a retractable writing instrument, characterized in that Effect of the Invention

[0084] According to the present invention, as the tip holder moves toward the front end side, the contact surface of the annular member receives a load from the guide surface of the barrel, and the presence of the notch in the annular member reduces the inner diameter of the annular member, allowing the barrel and the annular member to cooperate to grip the tip or tip holder without rattling (play).

[0085] According to the present invention, the contact surface of the annular member is provided so as to protrude radially outward at each of the intermediate positions between two circumferentially adjacent notches of the plurality of notches as viewed in the circumferential direction, so that even if the roundness of the cross section of the barrel is distorted, the annular member can reduce its diameter in the central axis direction of the tip with relatively high precision (while maintaining its roundness) (see FIG. 3(b)). Alternatively, according to the present invention, the inner peripheral surface of the annular member is provided with protruding portions protruding radially inward at each of the intermediate positions between two circumferentially adjacent notches of the plurality of notches as viewed in the circumferential direction, so that even if the roundness of the cross section of the barrel is distorted, the annular member can apply a gripping force in the central axis direction of the tip with relatively high precision (see FIG. 7(b)). Alternatively, according to the present invention, the guide surface of the barrel is provided so as to protrude radially inward at each intermediate position between two circumferentially adjacent notches of the plurality of notches when viewed in the circumferential direction, so that even if the roundness of the cross section of the barrel is distorted, the annular member can be reduced in diameter in the central axis direction of the tip with relatively high precision (while maintaining roundness) (see Figs. 11(b) and 12(b)). Any one or any combination of these features (see Fig. 14(b)) further reduces the risk of malfunction.

[0086] 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. This reduces the number of parts, simplifies assembly work, and significantly reduces the risk of malfunction. [Brief description of the drawings]

[0087] [Figure 1] FIG. 1 is a schematic vertical cross-sectional view of a retractable writing instrument in a first embodiment of the present invention, showing a state in which a tip (writing element) is not protruding. [Diagram 2] FIG. 2 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument of FIG. [Diagram 3] FIG. 3(a) is a cross-sectional view taken along line AA in FIG. 2, and FIG. 3(b) is a view equivalent to FIG. 3(a) in the case where the cross-section of the barrel has low roundness. [Figure 4] FIG. 4(a) is a view corresponding to FIG. 3(a) in the first embodiment of Patent Document 5 (a cross-sectional view taken along line AA in FIG. 14), and FIG. 4(b) is a view corresponding to FIG. 4(a) in the case where the cross-sectional circularity of the barrel is low. [Diagram 5] FIG. 5(a) is a plan view of the annular member of the retractable writing instrument of FIG. 1. FIG. 5(b) is a side view of the annular member of FIG. 5(a). FIG. 5(c) is a bottom view of the annular member of FIG. 5(a). FIG. 5(d) is a cross-sectional view taken along line AA of FIG. 5(b). FIG. 5(e) is a front view (viewed from the tip side) of the annular member of FIG. 5(a). FIG. 5(f) is a rear view of the annular member of FIG. 5(a). [Figure 6] FIG. 6 is a schematic diagram showing a state in which the tip comes into contact with the annular member during the tip protruding operation in the retractable writing instrument of FIG. [Figure 7] Figure 7(a) is a view corresponding to Figure 3(a) of a retractable writing instrument in a second embodiment of the present invention, and Figure 7(b) is a view corresponding to Figure 3(a) when the cross-section of the barrel has low circularity. [Figure 8] Fig. 8(a) is a plan view of the annular member of the retractable writing instrument of Fig. 7. Fig. 8(b) is a side view of the annular member of Fig. 8(a). Fig. 8(c) is a bottom view of the annular member of Fig. 8(a). Fig. 8(d) is a cross-sectional view taken along line AA of Fig. 8(b). Fig. 8(e) is a front view (viewed from the tip side) of the annular member of Fig. 8(a). Fig. 8(f) is a rear view of the annular member of Fig. 8(a). [Figure 9] Figure 9(a) is a view corresponding to Figure 3(a) of a retractable writing instrument in a third embodiment of the present invention, and Figure 9(b) is a view corresponding to Figure 9(a) when the cross-section of the barrel has low circularity. [Figure 10] FIG. 10(a) is a plan view of the annular member of the retractable writing instrument of FIG. 9. FIG. 10(b) is a side view of the annular member of FIG. 10(a). FIG. 10(c) is a bottom view of the annular member of FIG. 10(a). FIG. 10(d) is a cross-sectional view taken along line AA of FIG. 10(b). FIG. 8(e) is a front view (viewed from the tip side) of the annular member of FIG. 10(a). FIG. 10(f) is a rear view of the annular member of FIG. 10(a). [Figure 11]Figure 11(a) is a view corresponding to Figure 3(a) of a retractable writing instrument in the fourth embodiment of the present invention, and Figure 11(b) is a view corresponding to Figure 11(a) when the cross-sectional circularity of the barrel is low. [Figure 12] Figure 12(a) is a view corresponding to Figure 3(a) of a retractable writing instrument in the fifth embodiment of the present invention, and Figure 12(b) is a view corresponding to Figure 12(a) when the cross-sectional circularity of the barrel is low. [Figure 13] FIG. 1 is a schematic vertical cross-sectional view of a retractable writing instrument in a first embodiment of Patent Document 5, showing a state in which the tip (writing element) is not protruding. [Figure 14] FIG. 14 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument of FIG. [Figure 15] FIG. 15(a) is a perspective view of the annular member of the retractable writing instrument of FIG. 1. FIG. 15(b) is a plan view of the annular member of FIG. 15(a). FIG. 15(c) is a side view of the annular member of FIG. 15(a). FIG. 15(d) is a bottom view of the annular member of FIG. 15(a). FIG. 15(e) is a cross-sectional view taken along line AA of FIG. 15(c). FIG. 15(f) is a front view (viewed from the tip side) of the annular member of FIG. 15(a). FIG. 15(g) is a rear view of the annular member of FIG. 15(a). [Figure 16] 14 is a schematic diagram showing a state in which the tip comes into contact with the annular member during the tip protruding operation in the retractable writing instrument of FIG. 13. FIG. [Figure 17] 14 is a schematic diagram showing a state in which the tip of the retractable writing instrument of FIG. 13 is fully protruded during the tip protruding operation. FIG. [Figure 18] 14 is a schematic diagram showing the state in which the tip is protruded in the retractable writing instrument of FIG. 13 after the tip protruding operation has been completed. FIG. [Figure 19] FIG. [Figure 20] FIG. 2 is a perspective view of the rear end portion of the refill. [Figure 21] FIG. [Figure 22] FIG. 2 is a longitudinal cross-sectional view of a front shaft of an exemplary barrel. [Diagram 23]FIG. 2 is a longitudinal cross-sectional view of an intermediate shaft of an exemplary barrel. [Figure 24] FIG. 2 is a longitudinal cross-sectional view of an exemplary rear axle barrel. [Diagram 25] FIG. 2 is a vertical cross-sectional view of a knock member. [Figure 26] FIG. [Figure 27] FIG. [Figure 28] FIG. [Figure 29] 27 is a cross-sectional view taken along line CC in FIG. 26. [Diagram 30] 1 is a schematic diagram illustrating the principle of a rotating cam mechanism. [Diagram 31] 10 is a vertical cross-sectional view showing a state in which the retractable rotation member and the rear end of the refill are in contact with each other. FIG. [Diagram 32] 13 is a perspective view showing a state in which the retractable rotating member and the rear end of the refill are in contact with each other. FIG. [Diagram 33] FIG. 3 is a diagram corresponding to the enlarged view of FIG. 2, showing an embodiment in which the winding direction of the coil spring is reversed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0088] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0089] (First embodiment) FIG. 1 is a schematic vertical cross-sectional view of a retractable writing instrument 110 in the first embodiment of the present invention, showing a state in which a tip 114 (writing body) is not protruding. FIG. 2 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument 110 in this embodiment. FIG. 3(a) is a cross-sectional view taken along line AA in FIG. 2, and FIG. 3(b) is a view corresponding to FIG. 3(a) in the case where the roundness of the cross section of the barrel is low. For comparison, FIG. 4(a) is a view corresponding to FIG. 3(a) in the first embodiment of Patent Document 5 (a cross-sectional view taken along line AA in FIG. 14), and FIG. 4(b) is a view corresponding to FIG. 4(a) in the case where the roundness of the cross section of the barrel is low.

[0090] 5(a) is a plan view of the annular member 115 of the retractable writing instrument 110 of this embodiment, FIG. 5(b) is a side view of the annular member 115 of FIG. 5(a), FIG. 5(c) is a bottom view of the annular member of FIG. 5(a), FIG. 5(d) is a cross-sectional view along line AA of FIG. 5(b), FIG. 5(e) is a front view (viewed from the tip side) of the annular member of FIG. 5(a), and FIG. 5(f) is a rear view of the annular member of FIG. 5(a).

[0091] 6 is a schematic diagram showing a state in which tip 114 comes into contact with annular member 115 during the protruding operation of tip 114 in retractable writing instrument 110 of this embodiment. In retractable writing instrument 110 of this embodiment, tip 114 protrudes to the maximum extent via the state shown in FIG. 6 (generally the same state as FIG. 17), and after the protruding operation of tip 114 is completed, tip 114 is positioned in a protruding state for writing (generally the same state as FIG. 18).

[0092] The retractable writing instrument 110 of the first embodiment shown in Figs. 1 to 6 includes a cylindrical barrel 111 having an opening at the front end. As shown in Fig. 1, the barrel 111 in this embodiment has a rear portion 111r and a front portion 111m. The rear portion 111r and the front portion 111m are removably fixed to each other by a screw connection (screwed engagement). However, the rear portion 111r and the front portion 111m may be fixed to each other by a fitting connection, or may be formed integrally.

[0093] A tip holder 113 that is movable in the axial direction of the barrel 111 is housed inside the barrel 111. A tip 114, which is a writing body, is fixed to the front end of the tip holder 113. The tip 114 can appear and disappear from the opening of the barrel 111 as the tip holder 113 moves, as shown in FIG.

[0094] 2, the tip holder 113 has, in this order from the base end side to the tip end side, a base end portion 113a, a first collar portion 113b, and a second collar portion 113c. In this embodiment, the base end portion 113a and the first collar portion 113b are both cylindrical portions, and the second collar portion 113c is a truncated cone portion in this embodiment, and the relationship between their cross-sectional diameters is base end portion 113a>first collar portion 113b>second collar portion 113c.

[0095] 1, in this embodiment, an annular member 115 that is movable in the axial direction of the barrel 111 relative to the barrel 111 is loosely fitted around the inner periphery of the opening of the barrel 111. The front end of the annular member 115 is located forward of the front end of the barrel 111. The rear side of the annular member 115 has an expanded outer diameter and inner diameter, and covers the periphery of the tip 114 (φ2.5) without contacting it.

[0096] The annular member 115 is fixed to the front end of a coil spring 116 (an example of an elastic member). The coil spring 116 surrounds the second collar portion 113c of the chip holder 113 and the chip 114 in a loosely fitted state (with a gap), and the rear end of the coil spring 116 is constantly pressed by the base end portion 113a of the chip holder 113 (not fixed). As a result, the coil spring 116 connects the chip holder 113 and the annular member 115 so that they can move relative to each other. As shown in FIG. 6, the annular member 115 can move in the axial direction of the shaft tube 111 with respect to the shaft tube 111 as the chip holder 113 moves and the coil spring 116 expands and contracts.

[0097] The annular member 115 is made of resin (eg, polyacetal, polypropylene, or polyethylene) or metal (eg, brass).

[0098] As shown in Figures 5(a) to 5(f), the outer peripheral surface of the annular member 115 is provided, in this order from the front side, with a small outer diameter cylindrical surface 115a (φ3.6 mm, axial length 1.6 mm), a first truncated conical outer surface 115b (axial length 1.1 mm) as a tapered abutment surface, a medium outer diameter cylindrical surface 115c (φ4.85 mm, axial length 1.5 mm), a second truncated conical outer surface 115d (axial length 1.6 mm) as a tapered abutment surface, a first large outer diameter cylindrical surface 115e (φ6.3 mm, axial length 0.8 mm), a third truncated conical outer surface 115f (axial length 0.4 mm) as a tapered abutment surface, and a second large outer diameter cylindrical surface 115g (φ6.6 mm, axial length 3.3 mm).

[0099] 5(d), the inner peripheral surface of the annular member 115 is provided with 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 sweeping portion 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) in this order from the front side. As shown in FIG. 2, in this embodiment, the front end of the coil spring 116 is fixed (fitted) onto the four-sided sweeping portion 115ie.

[0100] Furthermore, the annular member 115 of this embodiment is provided with three slits 115s as cutouts. As shown in Fig. 5(a) to Fig. 5(f), the three slits 115s are arranged at equal intervals (every 120°) in the circumferential direction of the annular member 115. Furthermore, each of the three slits 115s has a width of 0.8 mm (dimension before assembly) and extends in the axial direction of the annular member 115 from the front end to approximately the center of the second truncated cone outer surface 115d (maximum axial length 5.5 mm).

[0101] In this embodiment, at each of the circumferential intermediate positions of two circumferentially adjacent (adjacent) slits 115s on the first truncated cone outer surface 115b (i.e., at three positions equally spaced in the circumferential direction), an outer protuberance 115p as an abutment surface is provided so as to protrude radially outward (the protuberance height is, for example, about 0.15 mm, the circumferential width is, for example, about 0.7 mm, the axial length is, for example, about 1.1 mm, and the upper surface is a part of the truncated cone surface). In this embodiment, the outer protuberance 115p as an abutment surface is formed in the shape of a rib extending in the axial direction of the annular member 115.

[0102] As a result, when a load is applied to the outer protrusion 115p (contact surface), 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.

[0103] On the other hand, as shown in Figures 2 and 6, the inner surface near the opening of the barrel 111 is provided with, in this order from the front side, a small inner diameter cylindrical surface 111ia (φ3.7 mm, axial length 1.2 mm), a first truncated conical inner surface 111ib (axial length 1.1 mm) as a tapered guide surface, a medium inner diameter cylindrical surface 111ic (φ4.95 mm, axial length 1.3 mm), a second truncated conical inner surface 111id (axial length 1.7 mm) as a tapered guide surface, a first large inner diameter cylindrical surface 111ie (φ6.5 mm, axial length 0.8 mm), a third truncated conical inner surface 111if (axial length 0.3 mm), a second large inner diameter cylindrical surface 111ig (φ6.7 mm, axial length 4.2 mm), and an annular protrusion 111ih (minimum aperture diameter φ6.5 mm) as a regulating element.

[0104] As a result, the outer protrusions 115p (contact surfaces) are adapted to receive a load from the first truncated cone inner surfaces 111ib (guide surfaces) as the chip holder 113 moves toward the front end side.

[0105] Coil spring 116 in this embodiment also has the function of automatically retracting tip holder 113 when tip 114 is retracted (for example, by sliding an operation part provided on the side of the writing implement to release a locking mechanism that maintains tip 114 in a protruding state). That is, coil spring 116 functions as a so-called knock spring. (The operating load is about 50gf to 300gf (about 0.49N to 2.94N). For example, the operating load when not in use (FIG. 2) is 68gf, the load at full stroke (see FIG. 17) is 288gf, and the operating load when writing (see FIG. 18) is 227gf. The spring constant is 0.23N / mm.)

[0106] The retractable writing instrument 110 configured as above operates as follows.

[0107] When not in use, the tip 114 (writing body) of the retractable writing instrument 110 is in a retracted state as shown in Fig. 1. Immediately after manufacture, the axial length of the coil spring 116 is 17 mm (a length previously compressed by about 2 mm), the annular member 115 is not contracted, and the small inner diameter cylindrical surface 115ia of the annular member 115 remains φ3.0 (>outer diameter of the tip 114). On the other hand, if the aforementioned "creep" occurs due to a long period of time remaining unused after manufacture, the axial length of the coil spring 116 is longer than 17 mm, the annular member 115 has already contracted, and the small inner diameter cylindrical surface 115ia of the annular member 115 is smaller than φ3.0 (it may maintain a range larger than the outer diameter of the tip 114, or it may be smaller than the outer diameter of the tip 114).

[0108] Then, when a tip protruding operation (for example, a sliding operation of an operating portion provided on the side surface of the writing instrument) is performed, tip 114 (writing body) of retractable writing instrument 110 reaches the state shown in FIG.

[0109] 6, the second collar portion 113c of the tip holder 113 is moved forward by the protruding operation of the tip 114. As a result, the annular member 115 is moved forward of the inner surface of the barrel 111 via the coil spring 116 and is further pressed against the forward side of the inner surface, so that the outer protruding portion 115p (contact surface) receives a load from the first truncated cone inner surface 111ib (guide surface), and the three slits 15s of the annular member 115 reduce the inner diameter of the annular member 115 (if the inner diameter has already been reduced due to the above-mentioned "creep" before the protruding operation of the tip 114, the degree of reduction in the diameter is further increased by the protruding operation of the tip 114).

[0110] The inner diameter when the diameter is reduced (in the state of FIG. 6) is designed to correspond to the outer diameter of the tip 114. That is, the minimum inner diameter when the diameter is reduced (for example, about 2.35 mm to 2.45 mm) allows the tip 114 (for example, φ2.5 mm) to slide smoothly in the axial direction, while the dimension is set to provide an effective anti-vibration function for the tip 114 in the radial direction. Also, 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 above-mentioned φ2.5 mm, the same (same dimensions) annular member 115 can provide a similarly effective anti-vibration function. That is, the retractable writing instrument 110 of this embodiment is compatible with different types of refills having different tip outer diameters in terms of the anti-vibration function. This can improve the convenience of the user.

[0111] In addition, according to this embodiment, the outer protuberance 115p (contact surface) of the annular member 115 is provided so as to protrude radially outward at each of the circumferential intermediate positions of two circumferentially adjacent (adjacent) slits 115s. Therefore, even if the roundness of the cross section of the barrel 111 is distorted, the annular member 115 can be reduced in diameter in the central axis direction of the tip with relatively high precision (while maintaining the roundness) (see FIG. 3(b)). This further reduces the risk of malfunction. In the embodiment described in Patent Document 5, when the roundness of the cross section of the barrel is distorted, the annular member may not be reduced in diameter with high precision in the central axis direction of the tip (see FIG. 4(b)).

[0112] Furthermore, in this embodiment, since the outer protrusion 115p (contact surface) is formed in a rib shape extending in the axial direction of the annular member 115, the load from the guide surface of the shaft tube 111 can be received in a more balanced manner.

[0113] In addition, since the outer protrusion 115p functions in a well-balanced manner as a contact surface, it is not necessary to design the coil spring 116 to have a large biasing force. This makes it possible to suppress the degree of creep described above, and also reduces the risk that the user will feel an unpleasant sense of resistance when operating the tip to protrude.

[0114] In this embodiment, the second truncated cone outer surface 115d comes into contact with the second truncated cone inner surface 111id, thereby defining the forward movement limit of the annular member 115. That is, in this embodiment, the second truncated cone outer surface 115d of the annular member 115 and the second truncated cone inner surface 111id of the barrel 111 function as stopper elements that define the forward movement limit of the annular member 115. However, such a stopper element can be omitted.

[0115] Then, when the tip protruding operation (for example, the sliding operation of the operation part provided on the side of the writing instrument) is continued, the tip 114 is in the most protruding state (generally the same state as in FIG. 17), and when the tip protruding operation is ended (for example, the sliding operation of the operation part provided on the side of the writing instrument is released), the tip 114 is positioned in a protruding state for writing (generally the same state as in FIG. 18). Usually, the position of the tip holder 113 is locked in this protruding state, and the protruding state of the tip 114 is maintained until the tip is retracted thereafter. At this time, the axial length of the coil spring 116 is 9.9 mm (compressed 10.1 mm from the state in FIG. 1), and the annular member 115 is maintained in a reduced diameter state by the restoring force of the coil spring 116. This allows the tip 114 to be held in a state without any rattling (play).

[0116] Here, even if the stopper element that determines the forward movement limit of annular member 115 functions, if the dimension of small inner diameter cylindrical surface 115ia on the inner surface of annular member 115 is sufficiently smaller than the outer diameter of tip 114 (if the diameter difference is about 0.05 mm or more: see paragraph 0110), since tip holder 113 and annular member 115 are connected to each other by coil spring 116 so as to be able to move relative to each other, it is guaranteed that tip 114 will be effectively gripped without rattling (play), even without high-precision dimensional control over the degree of reduction in the inner diameter of annular member 115, etc.

[0117] Thereafter, when the tip is retracted (for example, by re-sliding the operating part provided on the side of the writing instrument), for example, a locking mechanism (not shown) is released, and the tip 114 (writing body) of the retractable writing instrument 110 again becomes in its most protruding state (roughly the same state as in Figure 17), and then, due to the action (restoring force) of the coil spring 116, it returns to the retracted state of Figure 1 via the state of Figure 6.

[0118] 1, the tip holder 113 is moved rearward, and the load that the outer protrusion 115p (contact surface) received from the first frustoconical inner surface 111ib (guide surface) disappears. As a result, the inner diameter of the annular member 115, which had been reduced in diameter, returns to its original state (either to a non-reduced state or to a reduced state due to creep).

[0119] During the above-described process of the tip extension and retraction operation, the contact surface (outer protruding portion 115p) of the annular member 115 and the guide surface (first truncated cone inner surface 111ib) of the barrel 111 are always in contact with each other.

[0120] As described above, according to the retractable writing implement 110 of this embodiment, as the tip holder 113 moves toward the front end side, the contact surface (outer protrusion 115p) of the annular member 115 receives a load from the guide surface (first truncated cone inner surface 111ib) of the barrel 111, and the presence of the slits 115s in the annular member 115 reduces the inner diameter of the annular member 115. This allows the barrel 111 and the annular member 115 to cooperate to hold the tip 114 without any rattling (play).

[0121] Furthermore, according to the retractable writing instrument 110 of this embodiment, the contact surface of the annular member 115 is provided as an outer protruding portion 115p protruding radially outward at the middle position of each pair of circumferentially adjacent slits 115 of the three slits 115 when viewed in the circumferential direction, so that even if the roundness of the cross section of the barrel 111 is distorted, the annular member 115 can be reduced in diameter in the central axis direction of the tip 114 with relatively high precision (while maintaining roundness) (see FIG. 3(b)). This further reduces the risk of malfunction.

[0122] Furthermore, according to the retractable writing instrument 110 of this embodiment, the outer protrusion 115p (contact surface) is formed in a rib shape extending in the axial direction of the annular member 115, so that the load can be received from the guide surface (first truncated conical inner surface 111ib) of the barrel 111 in a more balanced manner.

[0123] In addition, according to the retractable writing instrument 110 of this embodiment, a stopper element functions to determine the limit of forward movement of the annular member 115, but since the dimension of the small inner diameter cylindrical surface 115ia on the inner 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 0110), and the tip holder 113 and the annular member 115 are connected to each other by the coil spring 116 so that they can move relative to each other, it is guaranteed that the tip 114 will be effectively held without any rattling (play) even without high-precision dimensional control over the degree of reduction in the inner diameter of the annular member 115, etc.

[0124] Furthermore, according to the retractable writing instrument 110 of this embodiment, three slits 115s as notches are arranged at equal intervals around the circumference 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 balanced manner around the circumference.

[0125] In addition, since the contact surface (outer protuberance 115p) of the annular member 115 and the guide surface (first truncated cone inner surface 111ib) of the shaft tube 111 are a corresponding truncated cone outer surface and a corresponding truncated cone inner surface, the contact surface of the annular member 115 can receive a load in a circumferentially balanced manner, and as a result, the diameter of the annular member 115 can be reduced in a circumferentially balanced manner. In this manner, it is preferable that the contact surface (outer protuberance 115p) of the annular member 115 and the guide surface (first truncated cone inner surface 111ib) of the shaft tube 111 are tapered toward their front ends. The tapered contact surface has a convex curved surface that is rotationally symmetric about the axis, and the tapered guide surface may be a concave curved surface or a concave truncated cone surface that is rotationally symmetric about the axis and has a curvature that is gentler than the curvature of the convex curved surface.

[0126] In addition, by appropriately changing the number, size, shape, etc. of the slits 115s, it is possible to adjust the degree of elasticity (ease of diameter reduction) of the annular member 115. In addition, by changing the material and / or thickness of the annular member 115, it is possible to adjust the degree of elasticity (ease of diameter reduction) of the annular member 115.

[0127] In this embodiment, an annular protrusion 111ih is provided on the inner peripheral surface of the shaft tube 111, and defines the rearward movement limit of the annular member 115. This makes it possible to effectively prevent the annular member 115 from excessively moving rearward (especially from falling off).

[0128] Furthermore, according to the retractable writing instrument 110 of this embodiment, the gripping portion (the portion with the smallest inner diameter when the diameter is reduced) of the annular member 115 that grips the tip 114 is located forward of the contact surface (the outer protruding portion 115p) of the annular member 115 (there is no gripping portion radially inward of the contact surface). This allows the tip 114 to be gripped further forward, and the tip 114 can be gripped more effectively without any rattling (play).

[0129] Moreover, according to the retractable writing instrument 110 of this embodiment, the rear end of the slit 115s is located forward of the coil spring 116. This makes it possible to maintain 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.

[0130] Furthermore, according to the retractable writing instrument 110 of this embodiment, the contact surface (outer protrusion 115p) of the annular member 115 and the guide surface (first truncated cone inner surface 111ib) of the barrel 111 are always in contact with each other. This prevents the contact surface of the annular member 115 and the guide surface of the barrel 111 from repeatedly coming into contact with and separating from each other every time the tip 114 is retracted, resulting in stable operation and a smooth operation feel for the user (no discomfort).

[0131] Moreover, according to 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 held over a longer axial range, ensuring that the tip 114 is held more effectively without any wobble (play). Furthermore, the fact that the retractable writing instrument 110 is equipped with a component (annular member 115) that acts as an anti-vibration component can be visually appealed to the user. Furthermore, the external shape of the retractable writing instrument 110 near the front end with the tip 114 protruding can be smoothly connected from the rear to the pen tip, which also has the effect of improving the aesthetic appearance.

[0132] Furthermore, according to the retractable writing instrument 110 of this embodiment, the amount (length) by which the annular member 115 protrudes forward from the opening of the barrel 111 is smaller than the axial movable range of the annular member 115. As a result, even when the annular member 115 is pushed in so as to be immersed in the opening of the barrel 111, the annular member 115 is still within the axial movable range, so that the annular member 115 can be effectively prevented from undesirably falling off, etc.

[0133] In addition, in the retractable writing instrument 110 of this embodiment, it is preferable that a soft member (abrasion member) for a thermochromic writing instrument is provided at the knock operation portion for the retraction operation of the tip 114 or at the rear of the barrel 111. When a conventional configuration is adopted for a thermochromic writing instrument, there is a risk that the tip (or tip holder) will rattle due to vibration during rubbing of writing, which may generate noise, but there is no such risk with the configuration of this embodiment. Therefore, it is also recommended to adopt the configuration of this embodiment for a thermochromic writing instrument.

[0134] Second embodiment Next, Fig. 7(a) is a view corresponding to Fig. 3(a) of a retractable writing instrument in the second embodiment of the present invention, and Fig. 7(b) is a view corresponding to Fig. 3(a) when the cross-section of the barrel has low roundness. Also, Fig. 8(a) is a plan view of the annular member of the retractable writing instrument in Fig. 7, Fig. 8(b) is a side view of the annular member in Fig. 8(a), Fig. 8(c) is a bottom view of the annular member in Fig. 8(a), Fig. 8(d) is a cross-sectional view of line AA in Fig. 8(b), Fig. 8(e) is a front view (view from the tip side) of the annular member in Fig. 8(a), and Fig. 8(f) is a rear view of the annular member in Fig. 8(a).

[0135] 8(a) to 8(f), the outer peripheral surface of the annular member 215 is provided with a small outer diameter cylindrical surface 215a (φ3.6 mm, axial length 1.6 mm), a first truncated cone outer surface 215b (axial length 1.1 mm) as a tapered abutment surface, a medium outer diameter cylindrical surface 215c (φ4.85 mm, axial length 1.5 mm), a second truncated cone outer surface 215d (axial length 1.6 mm) as a tapered abutment surface, a first large outer diameter cylindrical surface 215e (φ6.3 mm, axial length 0.8 mm), a third truncated cone outer surface 215f (axial length 0.4 mm) as a tapered abutment surface, and a second large outer diameter cylindrical surface 215g (φ6.6 mm, axial length 3.3 mm) in this order from the front side. The shapes and sizes of these elements are similar to those of the annular member 115 of the first embodiment.

[0136] 8(d), the inner peripheral surface of the annular member 215 is provided with a small inner diameter cylindrical surface 215ia (φ3.0 mm, axial length 2 mm), a first truncated cone inner surface 215ib (axial length 0.5 mm), a medium inner diameter cylindrical surface 215ic (φ3.6 mm, axial length 3.9 mm), a second truncated cone inner surface 215id (axial length 0.4 mm), a four-sided beveled portion 215ie (inscribed circle φ5.28 mm, axial length 0.9 mm), a large inner diameter cylindrical surface 215if (φ5.43 mm, axial length 2.1 mm), and a third truncated cone inner surface 215ig (axial length 0.4 mm) in this order from the front side. The shapes and sizes of these elements are also similar to those of the annular member 115 of the first embodiment. Also in this embodiment, the front end of the coil spring 116 is fixed (fitted) onto the four-sided sweeping portion 215ie (see FIG. 2).

[0137] In addition, the annular member 215 of this embodiment is provided with three slits 215s as cutouts. As shown in Fig. 8(a) to Fig. 8(f), the three slits 215s are arranged at equal intervals (every 120°) in the circumferential direction of the annular member 215. Each of the three slits 215s has a width of 0.8 mm (dimension before assembly) and extends in the axial direction of the annular member 215 from the front end to approximately the center of the second truncated cone outer surface 215d (maximum axial length 5.5 mm). The shape and size of the slits 215s are also similar to those of the slits 115s of the annular member 115 of the first embodiment.

[0138] In this embodiment, on the inner peripheral surface on the front side of the annular member 215, specifically, in the range from the front end of the small inner diameter cylindrical surface 215ia through the entire small inner diameter cylindrical surface 215ia and the first truncated conical inner surface 215ib to the front end of the medium inner diameter cylindrical surface 215ic (range of 3.0 mm in axial length), the inner protruding portions 215ip are provided so as to protrude radially inward at each of the circumferential intermediate positions of two circumferentially adjacent (adjacent) slits 215s (i.e., at three positions equally spaced in the circumferential direction). (On the small inner diameter cylindrical surface 215ia, the protrusion height is, for example, about 0.15 mm, the circumferential width is, for example, about 0.7 mm, and the upper surface is a part of a concave cylindrical surface, and on the first truncated cone inner surface 215ib, the protrusion height is, for example, about 0.15 mm, the circumferential width is, for example, about 0.7 mm, and the upper surface is a part of a concave truncated cone surface, and at the front end of the medium inner diameter cylindrical surface 215ic, it forms a slope rising toward the inner protrusion 215p at the rear end of the first truncated cone inner surface 215ib). Also, in this embodiment, the inner protrusion 215ip is formed in a rib shape extending in the axial direction of the annular member 215.

[0139] Even with the retractable writing implement of this embodiment, as the tip holder 113 moves toward the front end side, the contact surface (first truncated cone outer surface 215b) of the annular member 215 receives a load from the guide surface (first truncated cone inner surface 111ib) of the barrel 111, and the presence of the slits 215s in the annular member 215 reduces the inner diameter of the annular member 215. This allows the barrel 111 and the annular member 215 to cooperate to hold the tip 114 without any rattling (play).

[0140] Furthermore, according to the retractable writing implement of this embodiment, the inner circumferential surface of the annular member 215 is provided with inner protuberances 215ip that protrude radially inward at the middle positions of two circumferentially adjacent slits 215 of the three slits 215 when viewed in the circumferential direction, so that even if the circularity of the cross section of the barrel 111 is distorted, the annular member 215 can apply a gripping force in the central axis direction of the tip 114 with relatively high precision (see FIG. 7(b)). This further reduces the risk of malfunction.

[0141] Furthermore, according to the retractable writing instrument of this embodiment, the inner raised portion 215ip is formed in a rib shape extending in the axial direction of the annular member 215, so that a gripping force can be applied in the central axial direction of the tip 114 in a more balanced manner.

[0142] In addition, the retractable writing instrument of the second embodiment can also provide substantially the same effects as the retractable writing instrument 110 of the first embodiment.

[0143] Third embodiment Next, Fig. 9(a) is a view corresponding to Fig. 3(a) of a retractable writing instrument in the third embodiment of the present invention, and Fig. 9(b) is a view corresponding to Fig. 8(a) when the cross-section of the barrel has low roundness. Also, Fig. 10(a) is a plan view of the annular member of the retractable writing instrument in Fig. 9, Fig. 10(b) is a side view of the annular member in Fig. 10(a), Fig. 10(c) is a bottom view of the annular member in Fig. 10(a), Fig. 10(d) is a cross-sectional view of line AA in Fig. 10(b), Fig. 10(e) is a front view (view from the tip side) of the annular member in Fig. 10(a), and Fig. 10(f) is a rear view of the annular member in Fig. 10(a). The retractable writing instrument of the third embodiment has both the features of the outer protuberance 115p of the retractable writing instrument 110 of the first embodiment and the features of the inner protuberance 215ip of the retractable writing instrument of the second embodiment.

[0144] As shown in Figures 10(a) to 10(f), the outer peripheral surface of the annular member 315 is provided, from the front side, with a small outer diameter cylindrical surface 315a (φ3.6 mm, axial length 1.6 mm), a first truncated conical outer surface 315b (axial length 1.1 mm) as a tapered abutment surface, a medium outer diameter cylindrical surface 315c (φ4.85 mm, axial length 1.5 mm), a second truncated conical outer surface 315d (axial length 1.6 mm) as a tapered abutment surface, a first large outer diameter cylindrical surface 315e (φ6.3 mm, axial length 0.8 mm), a third truncated conical outer surface 315f (axial length 0.4 mm) as a tapered abutment surface, and a second large outer diameter cylindrical surface 315g (φ6.6 mm, axial length 3.3 mm), in this order. The shapes and sizes of these elements are similar to the annular member 115 of the first embodiment and the annular member 215 of the second embodiment.

[0145] 10(d), the inner peripheral surface of the annular member 315 is provided with a small inner diameter cylindrical surface 315ia (φ3 mm, axial length 2 mm), a first truncated cone inner surface 315ib (axial length 0.5 mm), a medium inner diameter cylindrical surface 315ic (φ3.6 mm, axial length 3.9 mm), a second truncated cone inner surface 315id (axial length 0.4 mm), a four-sided beveled portion 315ie (inscribed circle φ5.28 mm, axial length 0.9 mm), a large inner diameter cylindrical surface 315if (φ5.43 mm, axial length 2.1 mm), and a third truncated cone inner surface 315ig (axial length 0.4 mm) in this order from the front side. The shapes and sizes of these elements are also similar to those of the annular member 115 of the first embodiment and the annular member 215 of the second embodiment. Also in this embodiment, the front end of the coil spring 116 is fixed (fitted) onto the four-sided sweeping portion 315ie (see FIG. 2).

[0146] In addition, the annular member 315 of this embodiment is provided with three slits 315s as cutouts. As shown in Fig. 10(a) to Fig. 10(f), the three slits 315s are arranged at equal intervals (every 120°) in the circumferential direction of the annular member 315. Each of the three slits 315s has a width of 0.8 mm (dimension before assembly) and extends in the axial direction of the annular member 315 from the front end to approximately the center of the second truncated cone outer surface 315d (maximum axial length 5.5 mm). The shape and size of the slits 315s are also similar to those of the slits 115s of the annular member 115 of the first embodiment and the slits 215s of the annular member 215 of the second embodiment.

[0147] In this embodiment, at each of the circumferential intermediate positions of two circumferentially adjacent (adjacent) slits 315s on the first truncated cone outer surface 315b (i.e., at three positions equally spaced in the circumferential direction), an outer protuberance 315p as an abutment surface is provided so as to protrude radially outward (the protuberance height is, for example, about 0.15 mm, the circumferential width is, for example, about 0.7 mm, the axial length is, for example, about 1.1 mm, and the upper surface is a part of the truncated cone surface). In this embodiment, the outer protuberance 315p as an abutment surface is formed in the shape of a rib extending in the axial direction of the annular member 315.

[0148] Furthermore, in this embodiment, on the inner peripheral surface on the front side of the annular member 315, specifically, in the range from the front end of the small inner diameter cylindrical surface 315ia through the entire small inner diameter cylindrical surface 315ia and the first truncated conical inner surface 315ib to the front end of the medium inner diameter cylindrical surface 315ic (range of 3.0 mm in the axial length), at each of the circumferential intermediate positions of two circumferentially adjacent (adjacent) slits 315s (i.e., at three positions equally spaced in the circumferential direction), inner raised portions 315ip are provided so as to protrude radially inward. (On the small inner diameter cylindrical surface 315ia, the protrusion height is, for example, about 0.15 mm, the circumferential width is, for example, about 0.7 mm, and the upper surface is a part of a concave cylindrical surface, and on the first truncated cone inner surface 315ib, the protrusion height is, for example, about 0.15 mm, the circumferential width is, for example, about 0.7 mm, and the upper surface is a part of a concave truncated cone surface, and at the front end of the medium inner diameter cylindrical surface 315ic, it forms a slope rising toward the inner protrusion 315p at the rear end of the first truncated cone inner surface 315ib). In this embodiment, the inner protrusion 315ip is formed in a rib shape extending in the axial direction of the annular member 315.

[0149] Even with the retractable writing implement of this embodiment, as the tip holder 113 moves toward the front end side, the contact surface (outer protrusion 315p) of the annular member 315 receives a load from the guide surface (first truncated cone inner surface 111ib) of the barrel 111, and the presence of slits 315s in the annular member 315 reduces the inner diameter of the annular member 315. This allows the barrel 111 and the annular member 315 to cooperate to hold the tip 114 without any rattling (play).

[0150] Furthermore, according to the retractable writing implement of this embodiment, the contact surface of the annular member 315 is provided as an outer protruding portion 315p protruding radially outward at the middle position of each pair of circumferentially adjacent slits 315 of the three slits 315 when viewed in the circumferential direction, so that even if the roundness of the cross section of the barrel 111 is distorted, the annular member 315 can be reduced in diameter in the central axis direction of the tip 114 with relatively high precision (while maintaining the roundness) (see FIG. 9(b)). This further reduces the risk of malfunction.

[0151] Furthermore, according to the retractable writing instrument of this embodiment, the outer raised portion 315p (contact surface) is formed in a rib shape extending in the axial direction of the annular member 315, so that the load can be received from the guide surface (first truncated conical inner surface 111ib) of the barrel 111 in a more balanced manner.

[0152] Furthermore, according to the retractable writing implement of this embodiment, the inner circumferential surface of the annular member 315 is provided with inner protrusions 315ip that protrude radially inward at the middle positions of two circumferentially adjacent slits 315 of the three slits 315 when viewed in the circumferential direction, so that even if the circularity of the cross section of the barrel 111 is distorted, the annular member 315 can apply a gripping force relatively accurately in the central axis direction of the tip 114 (see FIG. 9(b)). This also further reduces the risk of malfunction.

[0153] Furthermore, according to the retractable writing instrument of this embodiment, the inner raised portion 315ip is formed in a rib shape extending in the axial direction of the annular member 315, so that a more balanced gripping force can be applied in the central axial direction of the tip 114.

[0154] In addition, the retractable writing instrument of the third embodiment can also provide substantially the same effects as the retractable writing instrument 110 of the first embodiment.

[0155] (Fourth embodiment) Next, Fig. 11(a) is a view corresponding to Fig. 3(a) of a retractable writing instrument in a fourth embodiment of the present invention, and Fig. 11(b) is a view corresponding to Fig. 11(a) when the cross-section of the barrel has low roundness. The retractable writing instrument of the fourth embodiment has the characteristics of the outer protuberance 115p in the retractable writing instrument 110 of the first embodiment in the barrel.

[0156] In this embodiment, instead of the annular member 115, an annular member 15 similar to that in the first embodiment of Patent Document 5 is used (see FIG. 15 and the like).

[0157] On the other hand, the barrel 411 of this embodiment has the same basic configuration as the barrel 111 shown in FIG. 2 and FIG. 6, and the inner peripheral surface near the opening of the barrel 411 is, 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) as a tapered guide surface, a medium inner diameter cylindrical surface 111ic (φ4.95 mm, axial length 1.3 mm), and a tapered Provided on the guide surface are a second truncated conical inner surface 111id (axial length 1.7 mm), a first large inner diameter cylindrical surface 111ie (φ6.5 mm, axial length 0.8 mm), a third truncated conical inner surface 111if (axial length 0.3 mm), a second large inner diameter cylindrical surface 111ig (φ6.7 mm, axial length 4.2 mm), and an annular protrusion 111ih (minimum aperture diameter φ6.5 mm) as a regulating element, in this order.

[0158] In this embodiment, on the second truncated cone inner surface 111id, at each of the circumferential intermediate positions of two circumferentially adjacent (adjacent) slits 115s (i.e., at three positions equally spaced in the circumferential direction), an inner protuberance 411p as a guide surface is provided so as to protrude radially inward (the protuberance height is, for example, about 0.15 mm, the circumferential width is, for example, about 0.7 mm, the axial length is, for example, about 0.7 mm, and the upper surface (inner surface) is a part of the concave truncated cone surface). In this embodiment, the inner protuberance 411p as a guide surface is formed in a rib shape extending in the axial direction of the shaft tube 411 (=the axial direction of the annular member 15).

[0159] Even with the retractable writing implement of this embodiment, as the tip holder 113 moves toward the front end side, the contact surface (first truncated cone outer surface 15b) of the annular member 15 receives a load from the guide surface (inner raised portion 411p) of the barrel 411, and the presence of the slits 15s in the annular member 15 reduces the inner diameter of the annular member 15. This allows the barrel 411 and the annular member 15 to cooperate to hold the tip 114 without any rattling (play).

[0160] Furthermore, according to the retractable writing implement of this embodiment, the contact surface of the barrel 411 is provided as an inner protuberance 411p that protrudes radially inward at the middle positions of two circumferentially adjacent slits 15 of the three slits 15 when viewed in the circumferential direction, so that even if the roundness of the cross section of the barrel 411 is distorted, the annular member 15 can be reduced in diameter in the central axis direction of the tip 114 with relatively high precision (while maintaining roundness) (see FIG. 11(b)). This further reduces the risk of malfunction.

[0161] Furthermore, according to the retractable writing instrument of this embodiment, the inner protrusion 411p is formed in a rib shape extending in the axial direction of the annular member 15, so that a load can be applied to the annular member 15 in a more balanced manner to reduce its diameter.

[0162] Fifth embodiment Next, Fig. 12(a) is a view corresponding to Fig. 3(a) of a retractable writing instrument in a fifth embodiment of the present invention, and Fig. 12(b) is a view corresponding to Fig. 12(a) when the cross-section of the barrel has low roundness. The retractable writing instrument of the fifth embodiment is obtained by replacing the annular member 15 in the retractable writing instrument of the fourth embodiment with the annular member 215 in the second embodiment. In addition, the retractable writing instrument of the fifth embodiment has the characteristic of the outer protuberance 315p in the retractable writing instrument of the third embodiment on the barrel.

[0163] Even with the retractable writing implement of this embodiment, as the tip holder 113 moves toward the front end side, the contact surface (first truncated cone outer surface 215b) of the annular member 215 receives a load from the guide surface (inner raised portion 411p) of the barrel 411, and the presence of the slits 215s in the annular member 215 reduces the inner diameter of the annular member 215. This allows the barrel 411 and the annular member 215 to cooperate to hold the tip 114 without any rattling (play).

[0164] Furthermore, according to the retractable writing implement of this embodiment, the contact surface of the barrel 411 is provided as an inner protuberance 411p protruding radially inward at the middle position between two circumferentially adjacent slits 215 of the three slits 215 when viewed in the circumferential direction, so that even if the roundness of the cross section of the barrel 411 is distorted, the annular member 215 can be reduced in diameter in the central axis direction of the tip 114 with relatively high precision (while maintaining roundness) (see FIG. 12(b)). This further reduces the risk of malfunction.

[0165] Furthermore, according to the retractable writing instrument of this embodiment, the inner protrusion 411p is formed in a rib shape extending in the axial direction of the annular member 215, so that a load can be applied to the annular member 215 in a more balanced manner to reduce its diameter.

[0166] Furthermore, according to the retractable writing implement of this embodiment, the inner circumferential surface of the annular member 215 is provided with inner protrusions 215ip that protrude radially inward at the middle positions of two circumferentially adjacent slits 215 of the three slits 215 when viewed in the circumferential direction, so that even if the circularity of the cross section of the barrel 411 is distorted, the annular member 215 can apply a gripping force in the central axis direction of the tip 114 with relatively high precision (see FIG. 12(b)). This also further reduces the risk of malfunction.

[0167] Furthermore, according to the retractable writing instrument of this embodiment, the inner protrusion 215ip is formed in a rib shape extending in the axial direction of the annular member 215, so that a gripping force can be applied in the central axial direction of the tip 114 in a more balanced manner.

[0168] (Additional information about refills) The retractable writing instrument 110 of each of the above embodiments is a writing instrument comprising a barrel 111, 411, a refill (writing body) contained in the barrel 111, 411, and a retractable mechanism that allows the tip 114 of the refill to be freely retracted and projected from the opening of the barrel 111, 411.

[0169] An example of a refill will be further described with reference to Figures 19 to 21. Referring to Figure 19, the refill 6 includes, for example, a pen tip (chip) 61, an ink reservoir 62 in which the pen tip 61 is press-fitted and fixed to the front end opening, a thermochromic ink filled in the ink reservoir 62, a follower (e.g., a high-viscosity fluid) filled adjacent to the rear end side of the thermochromic ink and moving forward as the thermochromic ink is consumed, and a tail plug 63 attached to the rear end opening of the ink reservoir 62. The tail plug 63 is provided with an air hole 63a that opens toward the rear end. The air hole 63a allows ventilation between the inside and outside of the ink reservoir 62.

[0170] The pen tip 61 is, for example, either a configuration consisting of only a metal ballpoint pen tip that rotatably holds a ball at its front end, or a configuration consisting of 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, a spring is housed that presses the ball at the front end forward. The spring is, for example, a configuration in which a rod portion is provided at the front end of a compression coil spring, and the front end of the rod portion is in contact with the rear surface of the ball. When not writing, the ball is in close contact with the inner surface of the inward front end edge of the front end of the ballpoint pen tip due to the forward bias of the spring. This prevents ink from leaking from the front end of the pen tip 61 and ink from evaporating.

[0171] (Additional information about the rear ends of the shaft tubes 111 and 411) The axle tube 111, 411 of this embodiment comprises, for example, a tapered cylindrical front axle 3 (see FIG. 22), a cylindrical intermediate axle 4 (see FIG. 23) connected to the rear end of the front axle 3, and a cylindrical rear axle 5 (see FIG. 24) connected to the rear end of the intermediate axle 4.

[0172] 24, for example, a mounting hole 52 may be provided in the rear end of the rear axle 5 in the front-rear direction, and a friction portion 53 made of an elastic material may be press-fitted into the mounting hole 52. This allows the friction portion 53 to be fixed to the outer surface of the rear end of the rear axle 5. Also, an inward protrusion 54 may be formed integrally on the inner surface of the rear axle 5.

[0173] The elastic material constituting the friction portion 53 is preferably, for example, a synthetic resin having elasticity (rubber, elastomer), such as silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin (styrene-ethylene-butylene-styrene copolymer), fluorine-based resin, chloroprene resin, nitrile resin, polyester-based resin, ethylene propylene diene rubber (EPDM), or a mixture of two or more kinds of rubber elastic materials, and a mixture of a rubber elastic material and a synthetic resin.

[0174] The elastic synthetic resin constituting the friction portion 53 is preferably made of a low-wear elastic material that hardly generates wear debris (eraser debris) during friction, rather than a high-wear elastic material (such as an eraser). The friction portion 53 can be provided on the outer surface of the rear end of the barrel 111, 411 in various ways. For example, the friction portion 53 made of an elastic material can be provided on the outer surface of the rear end of the barrel 111, 411 or the outer surface of the rear end of the rear axle 5 by press-fitting, engaging, screwing, fitting, bonding, two-color molding, or the like, or the entire barrel 111, 411 or the entire rear axle 5 can be integrally formed from an elastic material.

[0175] (Additional information about knock member 8) 25, a clip 83 extending in the front-rear direction may be fixed to the knock member 8. A ball portion may be protruded from the back surface of the clip 83. The knock member 8 is composed of, for example, a base portion 81 to which a rear end portion of the clip 83 is fixed, and a cylindrical shaft portion 82 that is integrally connected to the base portion 81 and extends forward from the base portion 81.

[0176] The knock member 8 is obtained by, for example, a molding of a synthetic resin (for example, polycarbonate resin). The clip 83 is obtained by, for example, a molding of a synthetic resin (for example, polycarbonate resin) or a metal material (for example, stainless steel). The knock member 8 and the clip 83 may be integrally formed by a synthetic resin.

[0177] As shown in FIG. 25, the front end of the shaft portion 82 may be integrally formed with cam teeth 82a that engage with the rear end of the protrusion 71 of the retractable rotation member 7 (see FIGS. 26 to 29).

[0178] To assemble the knock member 8, the base portion 81 of the knock member 8 is inserted into the first long hole 41 of the intermediate shaft 4 from the rear end (open portion) of the first long hole 41, and the shaft portion 82 of the knock member 8 is inserted into the intermediate shaft 4. Thereafter, while fitting the inner surface of the rear shaft 5 with the outer surface of the reduced diameter portion of the intermediate shaft 4, the base portion 81 of the knock member 8 is inserted into the second long hole 51 of the rear shaft 5 from the front end (open portion) of the second long hole 51 of the rear shaft 5 so that the first long hole 41 of the intermediate shaft 4 and the second long hole 51 of the rear shaft 5 communicate radially (so that they overlap radially). 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 are engaged to climb over each other), and the first long hole 41 and the second long hole 51 form a slide hole 21 extending in the front-rear direction, with the knock member 8 protruding radially outward from the slide hole 21. The knock member 8 is slidable in the front-rear direction along the slide hole 21 (is slidable in the front-rear direction).

[0179] The rear shaft 5, to which the friction portion 53 is fixed at its rear end, is connected to the rear end of the intermediate shaft 4, so that the friction portion 53 is always fixed to the rear end of the shaft tubes 111, 411. In addition, since the front shaft 3 and the intermediate shaft 4 are detachably connected by screwing, the refill 6 can be replaced at any time.

[0180] (Additional information on the haunting mechanism) The retractable mechanism of this embodiment is a side-slide type retractable mechanism that uses a rotating cam mechanism, and is composed of the above-mentioned knock member 8, the retractable rotating member 7 that moves back and forth to protrude or retract the nib 61 from the opening of the barrel 111, 411 each time the knock member 8 is moved forward, and rotates the refill 6 (and therefore the nib 61), the above-mentioned cam portion 43 that is provided within the barrel 111, 411 and can engage or disengage with the retractable rotating member 7 depending on the position of the knock member 8, and a knock spring 12 (e.g., a compression coil spring) that is provided within the barrel 111, 411 and urges the refill 6 rearward.

[0181] The retraction mechanism of this embodiment is a double knock type in which the knock member 8 is pressed forward (slid forward) for both the pen tip protruding operation and the pen tip retracting operation.

[0182] (Additional information about thermochromic ink) In the present embodiment, the thermochromic ink is preferably a reversible thermochromic ink. The reversible thermochromic ink may be of various types, such as a thermal decolorization type that is decolorized by heating from a colored state, a color memory retention type that alternately retains a colored state or a decolorized state in a specific temperature range, or a thermal color development type that develops color from a decolorized state by heating and returns to the decolorized state by cooling from the colored state, either alone or in combination.

[0183] As a coloring material contained in the reversible thermochromic ink, for example, a reversible thermochromic pigment in which a reversible thermochromic composition containing at least the three essential components of (i) an electron-donating color-forming organic compound, (ii) an electron-accepting compound, and (iii) a reaction medium that determines the temperature at which a reaction (coloring reaction) occurs in which the two are chemically bound to each other is preferably used.

[0184] (Additional information on the rotation of Refill 6) As described above, in this embodiment, each time the knock member 8 is moved forward, it moves back and forth to protrude or retract the pen tip 61 from the opening of the barrel 111, 411, and rotates the refill 6 (and therefore the pen tip 61). Writing instruments in which the pen tip 61 rotates in this manner are popular on the market because they can even out wear on the pen tip 61.

[0185] Fig. 30 is a schematic diagram for explaining the principle of the rotating cam mechanism. With reference to Fig. 30, when the knock member 8 is pressed (slid) forward from the pen tip retracted state (see Fig. 30(a)) against the rearward bias of the elastic body (not shown), the protrusion 71 of the retractable rotating member 7 engaged with the cam tooth 82a is pressed forward via the cam tooth 82a at the front end of the shaft portion 82 of the knock member 8. The protrusion 71 of the retractable rotating member 7 is moved forward along the cam groove 43b.

[0186] When the protrusion 71 of the retractable rotating member 7 is moved forward, the retractable rotating member 7 presses the refill 6 forward via the abutment relationship between the abutment portion 73 and the protrusion 63b of the tail plug 63. Then, the pen tip 61 protrudes to the outside from the opening of the barrel 111, 411.

[0187] When the knock member 8 is in the deepest position of the knock operation, the rear end of the protrusion 71 moves out of the cam groove 43b of the cam portion 43 and drops into the valley of the cam tooth 82a of the knock member 8, causing the protruding and retracting rotating member 7 to rotate slightly in the circumferential direction (see Figure 30(b)).

[0188] Subsequently, when the knock member 8 is returned to its original position by the backward urging of the elastic body, the rear end of the protrusion 71 moves so as to drop into the valley of the cam tooth 43a of the cam portion 43, and the retractable rotating member 7 rotates further in the circumferential direction accordingly (see FIG. 30(c)). In addition, the rear end of the protrusion 71 remains at the position of the valley of the cam tooth 43a of the cam portion 43, so the pen tip protruding state is maintained.

[0189] Next, when the knock member 8 is pushed (slid) forward from the pen tip extended state (see Figure 30c), the rear end of the protrusion 71 of the retractable rotating member 7 is engaged again by the cam teeth 82a at the front end of the shaft portion 82 of the knock member 8 and is pushed forward again.

[0190] When the knock member 8 is in the deepest position of the knock operation, the rear end of the protrusion 71 moves over the crest (tooth) of the cam tooth 43a of the cam portion 43 and drops into the valley of the cam tooth 82a of the knock member 8, and in conjunction with this, the retractable rotating member 7 rotates slightly in the circumferential direction (see FIG. 30(d)). Furthermore, when the knock member 8 is subsequently returned to its original position by the rearward urging of the resilient body, the protrusion 71 is introduced into the cam groove 43b, and the pen tip retracted state is maintained (see FIG. 30(a)).

[0191] 31 and 32 show the state in which the protruding piece 63b of the tail plug 63 and the abutting portion 73 of the retractable rotation member 7 are in contact with each other.

[0192] An abutment portion 73 on the front surface of the retractable rotating member 7 abuts against the protruding piece 63b of the tail plug 63 at the rear end of the refill 6, and a plurality of protrusions 72 on the front surface of the retractable rotating member 7 are inserted into the gaps 63c between the protruding pieces 63b of the tail plug 63 at the rear end of the refill 6, and are engaged in the circumferential direction. As a result, as the retractable rotating member 7 rotates in the circumferential direction, the refill 6 also rotates in the circumferential direction.

[0193] As described above, in this embodiment, the abutment portion 73 on the front surface of the retractable rotatable member 7 rotates the tail plug 63 at the rear end of the refill 6. However, a configuration in which the retractable rotatable member 7 transmits the rotational force to another portion of the refill 6 may also be adopted. For example, a configuration in which the tail plug 63 is not included and multiple protrusions are integrally formed at the rear end of the refill 6 may also be adopted.

[0194] (Additional information regarding the rotation of the annular members 115, 215, and 315) When the refill 6 is rotated relative to the barrel tube 111, 411 by the pressing operation of the knock member 8, the annular member 115, 215, 315 connected to the refill 6 via the coil spring 116 is also rotated relative to the barrel tube 111, 411.

[0195] 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, so there is no risk of the front end damaging the annular member 115. In addition, the annular member 115 connected to the refill 6 via the coil spring 116 is also rotated relative to the shaft tubes 111 and 411, 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, so there is no risk of the rear end damaging the tip holder 113. In addition, the refill 6, the annular member 115, and the coil spring 116 rotate together, so there is no risk of the smooth rotation of the refill 6 (and thus the pressing operation of the knock member 8) being hindered. Furthermore, since the rotation of the annular member 115 is visible, it is possible to provide visual interest to the user.

[0196] (Rotation direction of refill 6 and winding direction of coil spring 116) In the embodiment described above, the rotation direction of the refill 6 is clockwise when viewed from the rear end side, and the winding direction of the coil spring 116 is counterclockwise (a so-called left-handed spring) (extending counterclockwise from the beginning of winding: see FIG. 2).

[0197] However, if the rotational direction of the refill 6 and the winding direction of the coil spring 116 are aligned, the tip holder 113 (its coil spring abutment portion) will be oriented to push the rear end of the coil spring 116 when the refill 6 rotates, which makes the connection between the tip holder 113 and the coil spring 116 strong (for example, the two are hooked together), making it easier for the coil spring 116 to transmit the rotational force of the refill 6 to the annular member 115, which is preferable.

[0198] FIG. 33 is a view corresponding to FIG. 2, in which the winding direction of the coil spring 116 is reversed.

[0199] Here, it is further preferable that the coil spring abutment portion of chip holder 113 is provided with an uneven shape or the like so as to make the connection with the rear end of coil spring 116 stronger.

[0200] (R chamfering of the inner peripheral surface of the annular member 115) As explained with reference to Figures 5(d), 8(d) and 10(d), the inner surface of the annular member 115, 215, 315, excluding the inner raised portions 215ip, 315ip, is provided with, in this order from the front side, a small inner diameter cylindrical surface 115ia, 215ia, 315ia, a first truncated conical inner surface 115ib, 215ib, 315ib, a medium inner diameter cylindrical surface 115ic, 215ic, 315ic, a second truncated conical inner surface 115id, 215id, 315id, a four-sided sweep portion 115ie, 215ie, 315ie, a large inner diameter cylindrical surface 115if, 215if, 315if, and a third truncated conical inner surface 115ig, 215ig, 315ig. Here, a R chamfer may be provided at the connection region (boundary) between the small inner diameter cylindrical surface 115ia, 215ia, 31ia5 and the first truncated cone inner surface 115ib, 215ib, 315ib. In this case, when the tip 114 is inserted into the small inner diameter cylindrical surface 115ia, 215ia, 315ia, there is no catching, so that a smoother insertion can be achieved.

[0201] Furthermore, instead of providing the first truncated cone inner surface, a mode may be adopted in which the small inner diameter cylindrical surface and the medium inner diameter cylindrical surface are connected by a R chamfered portion (the first truncated cone inner surface is replaced by a chamfered portion). In this case as well, when the tip 114 is inserted into the small inner diameter cylindrical surface, there is no catching, and therefore a smoother insertion can be achieved.

[0202] (Other aspects of the notch) In the embodiment described above, the slit 115s is provided as the cutout. That is, the cutout is formed to penetrate the annular member 115 from the inner periphery side to the outer periphery side.

[0203] However, the notch is not limited to such an embodiment, and may be formed as a portion thinner than the surroundings (a portion of the thickness is cut away). For example, a thin portion (e.g., 0.2 mm thick) may remain at the portion of the slit 115s.

[0204] Even in such a modified example, when a load is applied to the first truncated cone outer surface or the outer protrusion (abutment surface), the inner diameter of the annular member can flexibly shrink, and when the load is released, the inner diameter of the annular member can elastically return to its original state. [Explanation of symbols]

[0205] 10 Retractable writing instrument (Patent Document 5) 11 Shaft tube 11ia Small inner diameter cylindrical surface 11ib First truncated cone inner surface 11ic Medium inner diameter cylindrical surface 11id 2nd truncated cone inner surface 11ie First large bore cylindrical surface 11if Third truncated cone inner surface 11ig Second large inner diameter cylindrical surface 11ih Annular protrusion 11m front part 11r rear part 13 Chip holder 13a Proximal end 13b 1st Color Section 13c 2nd Color Section 14 Chips 15 Annular member (Patent Document 5, fourth embodiment) 15a Small outer diameter cylindrical surface 15b First truncated cone outer surface 15c Medium outer diameter cylindrical surface 15d Second truncated cone outer surface 15e First large outer diameter cylindrical surface 15f Third truncated cone outer surface 15g Second large outer diameter cylindrical surface 15ia Small inner diameter cylindrical surface 15ib First truncated cone inner surface 15ic Medium inner diameter cylindrical surface 15id 2nd truncated cone inner surface 15ie Four-sided cleaning section 15if Large inner diameter cylindrical surface 15ig 3rd truncated cone inner surface 15s slit 16 Coil spring 110 Retractable writing instrument 111 Shaft cylinder 111ia Small inner diameter cylindrical surface 111ib First truncated cone inner surface 111ic Medium bore cylindrical surface 111id Second truncated cone inner surface 111ie 1st large bore cylindrical surface 111if Third truncated cone inner surface 111ig Second large inner diameter cylindrical surface 111ih Annular protrusion 111m front part 111r rear part 113 Chip holder 113a Proximal end 113b 1st Color Section 113c 2nd Color Section 114 Chips 115 Annular member (first embodiment) 115a Small outer diameter cylindrical surface 115b First truncated cone outer surface 115c Medium outer diameter cylindrical surface 115d Second truncated cone outer surface 115e First large outer diameter cylindrical surface 115f Third truncated cone outer surface 115g Second large outer diameter cylindrical surface 115p outer ridge 115ia Small inner diameter cylindrical surface 115ib First truncated cone inner surface 115ic Medium inner diameter cylindrical surface 115id Second truncated cone inner surface 115ie Four-sided sweeper 115if Large inner diameter cylindrical surface 115ig 3rd truncated cone inner surface 115s Slit 116 Coil Spring 215 Annular member (Second embodiment, fifth embodiment) 215a Small outer diameter cylindrical surface 215b First truncated cone outer surface 215c Medium outer diameter cylindrical surface 215d Second truncated cone outer surface 215e First large outer diameter cylindrical surface 215f Third truncated cone outer surface 215g Second large outer diameter cylindrical surface 215ia Small inner diameter cylindrical surface 215ib First truncated cone inner surface 215ic Medium bore cylindrical surface 215id Second truncated cone inner surface 215ie Four-sided sweeper 215if Large inner diameter cylindrical surface 215ig 3rd truncated cone inner surface 215ip inner ridge 215s Slit 315 Annular member (third embodiment) 315a Small outer diameter cylindrical surface 315b First truncated cone outer surface 315c Medium outer diameter cylindrical surface 315d Second truncated cone outer surface 315e First large outer diameter cylindrical surface 315f 3rd truncated cone outer surface 315g Second large outer diameter cylindrical surface 315p outer ridge 315ia Small inner diameter cylindrical surface 315ib First truncated cone inner surface 315ic Medium bore cylindrical surface 315id Second truncated cone inner surface 315ie Four-sided cleaning section 315if Large inner diameter cylindrical surface 315ig 3rd truncated cone inner surface 315ip inner ridge 315s Slit 411 barrel (fourth embodiment, fifth embodiment) 411p medial ridge 3 Front axle 32 Main unit 33 Gripping part 4 Intermediate shaft 41 First slot 42 Stepped section 43 Cam section 43a Cam teeth 43b Cam groove 44 External process 5 rear axle 51 Second slot 52 Mounting hole 53 Friction part 54 Introvert process 6 Refill (Cursive) 61 Pen Tip 62 Ink reservoir 63 Tail plug 63a Air hole 63b Projection piece 63c Gap 63d Small diameter section 63e Large diameter section 63f Tsubabe 63g engaging surface 63p External process 63t Auxiliary taper part 7. Rotating parts 71 protrusion 72 Protrusion 72a Engagement surface 73 Contact part 74 Annular auxiliary protrusion 74t Auxiliary contact surface 78 External process 8 Knock parts 81 Base 82 Shaft 82a Cam teeth 83 clips 88 Introvert process

Claims

1. A barrel having an opening at a front end; a tip holder accommodated inside the barrel and movable in the axial direction of the barrel; a tip fixed to a front end of the tip holder and capable of appearing and disappearing from the opening of the barrel as the tip holder moves; an annular member that is loosely fitted to an inner periphery of the opening of the barrel and is movable in an axial direction of the barrel relative to the barrel; an elastic member capable of connecting the chip holder and the annular member so as to be movable relative to each other; Equipped with a contact surface is formed on at least a portion of the outer periphery of the annular member, the contact surface being adapted to contact a portion of the inner surface of the barrel as the tip holder moves toward the front end side; A notch is formed in a portion of the annular member, and an inner diameter of the annular member is reduced 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, with which the abutment surface abuts as the tip holder moves toward the front end side; the contact surface receives the load from the guide surface as the tip holder moves toward the front end side, A plurality of the notches are disposed at equal intervals in the circumferential direction of the annular member, The abutment surface is provided so as to protrude radially outward at each of intermediate positions between two circumferentially adjacent notches of the plurality of notches as viewed in the circumferential direction. A retractable writing instrument characterized by:

2. The contact surface is formed in a rib shape extending in the axial direction of the annular member.

2. The retractable writing instrument according to claim 1 .

3. A barrel having an opening at a front end; a tip holder accommodated inside the barrel and movable in the axial direction of the barrel; a tip fixed to a front end of the tip holder and capable of appearing and disappearing from the opening of the barrel as the tip holder moves; an annular member that is loosely fitted to an inner periphery of the opening of the barrel and is movable in an axial direction of the barrel relative to the barrel; an elastic member capable of connecting the chip holder and the annular member so as to be movable relative to each other; Equipped with a contact surface is formed on at least a portion of the outer periphery of the annular member, the contact surface being adapted to contact a portion of the inner surface of the barrel as the tip holder moves toward the front end side; A notch is formed in a portion of the annular member, and an inner diameter of the annular member is reduced 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, with which the abutment surface abuts as the tip holder moves toward the front end side; the contact surface receives the load from the guide surface as the tip holder moves toward the front end side, A plurality of the notches are disposed at equal intervals in the circumferential direction of the annular member, The inner peripheral surface of the annular member is provided with raised portions that protrude radially inward at intermediate positions between two circumferentially adjacent notches of the plurality of notches as viewed in the circumferential direction. A retractable writing instrument characterized by:

4. The raised portion is formed in a rib shape extending in the axial direction of the annular member.

4. The retractable writing instrument according to claim 3.

5. The inner peripheral surface of the annular member is provided with raised portions that protrude radially inward at intermediate positions between two circumferentially adjacent notches of the plurality of notches as viewed in the circumferential direction.

3. The retractable writing instrument according to claim 1 or 2.

6. The raised portion is formed in a rib shape extending in the axial direction of the annular member.

6. The retractable writing instrument according to claim 5.

7. A barrel having an opening at a front end; a tip holder accommodated inside the barrel and movable in the axial direction of the barrel; a tip fixed to a front end of the tip holder and capable of appearing and disappearing from the opening of the barrel as the tip holder moves; an annular member that is loosely fitted to an inner periphery of the opening of the barrel and is movable in an axial direction of the barrel relative to the barrel; an elastic member capable of connecting the chip holder and the annular member so as to be movable relative to each other; Equipped with a contact surface is formed on at least a portion of the outer periphery of the annular member, the contact surface being adapted to contact a portion of the inner surface of the barrel as the tip holder moves toward the front end side; A notch is formed in a portion of the annular member, and an inner diameter of the annular member is reduced 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, with which the abutment surface abuts as the tip holder moves toward the front end side; the contact surface receives the load from the guide surface as the tip holder moves toward the front end side, A plurality of the notches are disposed at equal intervals in the circumferential direction of the annular member, The guide surface is provided so as to protrude radially inward at each intermediate position between two circumferentially adjacent notches of the plurality of notches as viewed in the circumferential direction. A retractable writing instrument characterized by:

8. The guide surface is formed in a rib shape extending in the axial direction of the annular member.

8. The retractable writing instrument according to claim 7.

9. A stopper element provided on the barrel and / or the annular member to define a rearward movement limit of the annular member The retractable writing instrument according to any one of claims 1 to 4, 7 and 8, further comprising:

10. Each of the plurality of notches is a slit extending in the axial direction of the annular member.

9. The retractable writing instrument according to claim 1, wherein the retractable writing instrument is a retractable writing instrument.

11. The abutment surface is tapered toward a front end, The guide surface also tapers toward the front end.

9. The retractable writing instrument according to claim 1, wherein the retractable writing instrument is a retractable writing instrument.

12. The abutment surface has a frustoconical surface.

12. The retractable writing instrument according to claim 11.

13. The elastic member is a coil spring.

9. The retractable writing instrument according to claim 1, wherein the retractable writing instrument is a retractable writing instrument.

14. The annular member and the elastic member are fixed to each other, the resilient member is connectable to an annular collar of the chip holder; The elastic member is separable from the annular collar of the chip holder.

9. The retractable writing instrument according to claim 1, wherein the retractable writing instrument is a retractable writing instrument.

15. The contact surface and the guide surface are always in contact with each other.

9. The retractable writing instrument according to claim 1, wherein the retractable writing instrument is a retractable writing instrument.

16. The annular member protrudes forward from the opening of the barrel.

9. The retractable writing instrument according to claim 1, wherein the retractable writing instrument is a retractable writing instrument.

17. A soft member is provided at an operating portion for operating the tip to extend or retract, or at the rear of the barrel.

9. The retractable writing instrument according to claim 1, wherein the retractable writing instrument is a retractable writing instrument.

18. A knock member provided so as to be slidable in the front-rear direction relative to the barrel. Further comprising: The tip is moved back and forth so as to alternately protrude and retract from the opening of the barrel every time the knock member is moved forward, 9. The retractable writing instrument according to claim 1, wherein the annular member is adapted to rotate relative to the barrel every time the knock member is moved forward.

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