Retractable writing instrument

Abstract

To provide a retractable writing instrument which prevents rattling of a tip in writing and provides stable writing feeling, is unsusceptible to actuation failure, and can keep a smoothly protruding operation for an extended period.SOLUTION: A retractable writing instrument includes a barrel having an opening in a front end thereof, a tip holder which can move in an axial direction of the barrel, a tip which can retract along with a movement of the tip holder, an annular member which is fitted in an inner periphery of the opening of the barrel with a play therebetween and can move in the axial direction, and an elastic member which can connect the tip holder and the annular member to each other with their relative movement allowed. An abutment surface tapered toward a front end is formed in at least a part of an outer periphery of the annular member. A cutout is formed in a 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. In a forward inner periphery of the annular member, a tip abutment surface which comes into abutment contact with a circumference of a tip is formed. At least rearward region of the tip abutment surface is tapered toward a front end.SELECTED DRAWING: Figure 4

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. 8 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. 9 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument 10 in this embodiment.

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

[0009] Furthermore, Figure 11 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 12 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 13 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. 8 to Fig. 13 includes a cylindrical barrel 11 having an opening at the front end. As shown in Fig. 8 to Fig. 10, 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 11 to 13.

[0012] 9, 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] 9, in this embodiment, 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 11 to 13, 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 10(a) to 10(g), the outer peripheral surface of the annular member 15 is provided, in that 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] 10(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. 9, 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. 10(a) to Fig. 10(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 9, 12 and 13, 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. 9) is 68gf, the load at full stroke (FIG. 12) is 288gf, and the operating load when writing (FIG. 13) 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 8 and 9. 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] 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, the tip 14 (writing body) of the retractable writing instrument 10 reaches the state shown in FIG.

[0026] 11, 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. 13. Normally, the position of the tip holder 13 is locked in the protruding state of FIG. 13, 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 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 0103), 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, thereby ensuring that the tip 14 is 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 12, and then, due to the action (restoring force) of the coil spring 16, it returns to the retracted state shown in Figure 9 via the state shown in Figure 11.

[0033] 9, 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 0103), 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, even when the tip 14 (writing body) is retracted as shown in FIG. 9, 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 tip 14 (writing body) is not protruded for a long period of time), 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, the user may feel an unpleasant sense of resistance when performing the operation of protruding the tip 14 thereafter.

[0053] More specifically, referring to FIG. 10(e), when tip 14 passes through the connection area (ridge-like boundary) between small inner diameter cylindrical surface 15ia (φ3.0 mm, axial length 2 mm) of annular member 15 and first truncated conical inner surface 15ib (smaller diameter side φ3.0 mm, larger diameter side φ3.6 mm, axial length 0.5 mm, inclination angle (gradient) approximately 31° (arctan(1.8(=φ3.6 / 2) / 3.0(=0.5×φ3.6 / (φ3.6−φ3.0))), if the degree of diameter reduction of annular member 15 exceeds the desired value, the user may feel an uncomfortable resistance.

[0054] In this regard, in the configuration of the first embodiment of Patent Document 5, 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, the present inventors found that since both the second truncated cone outer surface 15d and the second truncated cone inner surface 11id are tapered toward the rear end, the above-mentioned "creep" cannot be sufficiently suppressed.

[0055] The present invention has been made in consideration of the above-mentioned findings, and its object is to provide a retractable writing instrument that prevents the tip from rattling when writing, resulting in a stable writing feel, while reducing the risk of malfunction and capable of maintaining smooth tip protruding action for a long period of time. [Means for solving the problem]

[0056] 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 notch is formed in a portion of the annular member so 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 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 is adapted to receive the load from the guide surface as the tip holder moves toward the front end; a tip abutment surface is formed on the inner circumference of the front side of the annular member, which abuts against the periphery of the tip when the inner diameter of the annular member reduces as the tip holder moves toward the front end; and a loose fit surface is formed on the inner circumference of the rear side of the annular member, which allows axial movement of the tip and / or the tip holder without abutting against the tip and / or the tip holder, and at least the rear region of the tip abutment surface is tapered toward the front end.This is a retractable writing instrument.

[0057] 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).

[0058] According to the present invention, at least the rear region of the tip contact surface is tapered toward the front end, which significantly reduces the resistance when the tip starts to contact the tip contact surface. The inclination angle of the tapered region is preferably about 7° to 9°. The axial length of the tapered region is preferably about 1.0 mm to 1.2 mm.

[0059] For example, it is preferable that at least the rear region of the tip abutment surface has a truncated cone surface, which makes it possible to more effectively reduce the resistance when the tip starts to abut against the tip abutment surface.

[0060] It is also preferable that at least a rear end region of the tip abutment surface is provided with a R-chamfer, which can more effectively reduce the resistance when the tip starts to abut against the tip abutment surface, particularly when the tip is offset in any radial direction.

[0061] More specifically, when a transition surface is formed adjacent to the rear side of the tip abutment surface, tapering toward the front end and having an inclination angle larger than the inclination angle of the tapered shape of at least the rear region of the tip abutment surface, it is preferable that a R chamfer is provided between at least the rear end region of the tip abutment surface and the transition surface, which makes it possible to more effectively reduce the resistance when the tip starts to abut against the tip abutment surface, particularly when the position of the tip is biased in any radial direction.

[0062] In the present invention, a front region of the tip contact surface may be a cylindrical surface or a substantially cylindrical surface, or the entire tip contact surface may be tapered toward the front end.

[0063] 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.

[0064] 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).

[0065] 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.

[0066] Preferably, the notches are arranged at equal intervals in a circumferential direction of the annular member, and each of the notches is a slit extending in an axial direction of the annular member. In this case, the inner diameter of the annular member can be reduced in a balanced manner in the circumferential direction.

[0067] 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.

[0068] 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.

[0069] Also, preferably, the elastic member is a coil spring.

[0070] 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.

[0071] 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).

[0072] 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).

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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 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 that they can move relative to each other; an abutment surface is formed on at least a part of the outer circumference of the annular member, which abuts against a part of the inner surface of the barrel as the tip holder moves toward the front end side; a notch is formed in a part of the annular member, and 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 portion of the inner surface against which the abutment surface abuts as the tip holder moves toward the front end, and the abutment surface is adapted to receive the load from the guide surface as the tip holder moves toward the front end; a tip abutment surface is formed on the inner circumference of the front side of the annular member which abuts against the periphery of the tip when the inner diameter of the annular member reduces as the tip holder moves toward the front end, and a loose fit surface is formed on the inner circumference of the rear side of the annular member which allows axial movement of the tip and / or the tip holder without abutting against the tip and / or the tip holder, and at least the rear region of the tip abutment surface is tapered toward the front end, making this a barrel for a retractable writing instrument. Effect of the Invention

[0077] According to the present invention, the contact surface of the annular member receives a load from the guide surface of the barrel as the tip holder moves toward the front end, and the presence of the notch in the annular member reduces the inner diameter of the annular member. This allows the barrel and the annular member to cooperate to hold the tip or tip holder without any rattle (play). Also, according to the present invention, at least the rear region of the tip contact surface is tapered toward the front end, so that the resistance when the tip begins to contact the tip contact surface can be significantly reduced. Also, according to the present invention, the elastic member can function as a "knock spring", so there is no need to use a separate coil spring for the knock spring. This reduces the number of parts, facilitates assembly work, and significantly reduces the risk of malfunction. [Brief description of the drawings]

[0078] [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(a) is a perspective view of the annular member of the retractable writing instrument of FIG. 1. FIG. 2(b) is a plan view of the annular member of FIG. 2(a). FIG. 2(c) is a side view of the annular member of FIG. 2(a). FIG. 2(d) is a bottom view of the annular member of FIG. 2(a). FIG. 2(e) is a cross-sectional view taken along line AA of FIG. 2(c). FIG. 2(f) is a front view (viewed from the tip side) of the annular member of FIG. 2(a). FIG. 2(g) is a rear view of the annular member of FIG. 2(a). [Diagram 3] FIG. 3 is an enlarged view of FIG. 2(e). [Figure 4] FIG. 4 is a schematic vertical sectional view for explaining the operation of the retractable writing instrument according to the first embodiment of the present invention. [Diagram 5] FIG. 5 is an enlarged cross-sectional view of an annular member of a retractable writing instrument according to a second embodiment of the present invention (corresponding to FIG. 3). [Figure 6] FIG. 6 is a schematic vertical sectional view for explaining the operation of the retractable writing instrument according to the second embodiment of the present invention. [Figure 7]FIG. 7 is a diagram illustrating a preferred shape of the tip. [Figure 8] 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 9] FIG. 9 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument of FIG. [Figure 10] FIG. 10(a) is a perspective view of the annular member of the retractable writing instrument of FIG. 8. FIG. 10(b) is a plan view of the annular member of FIG. 10(a). FIG. 10(c) is a side view of the annular member of FIG. 10(a). FIG. 10(d) is a bottom view of the annular member of FIG. 10(a). FIG. 10(e) is a cross-sectional view taken along line AA of FIG. 10(c). FIG. 10(f) is a front view (viewed from the tip side) of the annular member of FIG. 10(a). FIG. 10(g) is a rear view of the annular member of FIG. 10(a). [Figure 11] 9 is a schematic diagram showing a state in which the tip comes into contact with the annular member during a tip protruding operation in the retractable writing instrument of FIG. 8. FIG. [Figure 12] 9 is a schematic diagram showing a state in which the tip is most protruded during a tip protruding operation in the retractable writing instrument of FIG. 8. FIG. [Figure 13] 9 is a schematic diagram showing a state in which the tip is protruded in the retractable writing instrument of FIG. 8 after the tip protruding operation has been completed. FIG. [Figure 14] FIG. [Figure 15] FIG. 2 is a perspective view of the rear end portion of the refill. [Figure 16] FIG. [Figure 17] FIG. 2 is a longitudinal cross-sectional view of a front shaft of an exemplary barrel. [Figure 18] FIG. 2 is a longitudinal cross-sectional view of an intermediate shaft of an exemplary barrel. [Figure 19] FIG. 2 is a longitudinal cross-sectional view of an exemplary rear axle barrel. [Figure 20] FIG. 2 is a vertical cross-sectional view of a knock member. [Figure 21] FIG. [Figure 22] FIG. [Diagram 23] FIG. [Figure 24] 24 is a cross-sectional view taken along line CC in FIG. 23. [Diagram 25] 1 is a schematic diagram illustrating the principle of a rotating cam mechanism. [Figure 26] 11 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. [Figure 27] 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. [Figure 28] FIG. 2 is a diagram corresponding to the enlarged view of FIG. 1, showing an embodiment in which the winding direction of the coil spring is reversed. [Figure 29] Fig. 29(a) is a perspective view of an annular member of a retractable writing implement according to a modified example. Fig. 29(b) is a plan view of the annular member of Fig. 29(a). Fig. 29(c) is a side view of the annular member of Fig. 29(a). Fig. 29(d) is a bottom view of the annular member of Fig. 29(a). Fig. 29(e) is a cross-sectional view taken along line AA of Fig. 29(c). Fig. 29(f) is a front view (viewed from the tip side) of the annular member of Fig. 29(a). Fig. 29(g) is a rear view of the annular member of Fig. 29(a). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0079] Two embodiments of the present invention will now be described with reference to the drawings.

[0080] First Embodiment FIG. 1 is a schematic vertical cross-sectional view of a retractable writing instrument 110 according to a first embodiment of the present invention, showing a state in which a tip 114 (writing element) is not protruding.

[0081] Also, Fig. 2(a) is a perspective view of the annular member 115 of the retractable writing instrument 110 of this embodiment, Fig. 2(b) is a plan view of the annular member 115 of Fig. 2(a), Fig. 2(c) is a side view of the annular member 115 of Fig. 2(a), Fig. 2(d) is a bottom view of the annular member of Fig. 2(a), Fig. 2(e) is a cross-sectional view of line AA of Fig. 2(c), Fig. 2(f) is a front view (view from the tip side) of the annular member of Fig. 2(a), and Fig. 2(g) is a rear view of the annular member of Fig. 2(a). Also, Fig. 3 is an enlarged view of Fig. 2(e).

[0082] 4 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 most proximally via the state shown in FIG. 4 (almost the same state as FIG. 12), and after the protruding operation of tip 114 is completed, tip 114 is positioned in a protruding state for writing (almost the same state as FIG. 13).

[0083] The retractable writing instrument 110 of the first embodiment shown in Figs. 1 to 4 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 by a screw connection (screwed engagement). However, the rear portion 111r and the front portion 111m may be fixed by a fitting connection, or may be formed integrally.

[0084] 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.

[0085] 4, 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.

[0086] 4, 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.

[0087] 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. 4, 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.

[0088] The annular member 115 is made of resin (eg, polyacetal, polypropylene, or polyethylene) or metal (eg, brass).

[0089] As shown in Figures 2(a) to 2(g), 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).

[0090] 2(e) and 3, the inner peripheral surface of the annular member 115 is made up of, from the front side, a small inner diameter cylindrical surface 115ia (φ3 mm, axial length 0.2 mm) (at least the rear side region of the tip abutment surface)), an auxiliary truncated conical inner surface 115is for tip abutment and guide (inclination angle of approximately 8°, axial length 1.2 mm), a first truncated conical inner surface 115ib (inclination angle of approximately 30°, axial length 0.4 mm), and a medium inner diameter cylindrical surface 115ic (φ 3.6 mm, axial length 3.9 mm) (which may be a truncated cone surface with a gentle inclination angle instead of a cylindrical surface), 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) are provided in this order. As shown in Fig. 4, in this embodiment, the front end of the coil spring 116 is fixed (fitted and fixed) onto the four-sided sweeping portion 115ie.

[0091] The small inner diameter cylindrical surface 115ia and the auxiliary truncated conical inner surface 115is form a tip abutment surface that abuts against the periphery of tip 114 when the inner diameter of annular member 115 decreases as tip holder 113 moves toward the front end. The small inner diameter cylindrical surface 115ia is a front region of the tip abutment surface, and the auxiliary truncated conical inner surface 115is is a rear region of the tip abutment surface.

[0092] In addition, the first truncated conical inner surface 115ib, the medium inner diameter cylindrical surface 115ic, the second truncated conical inner surface 115id, the four-sided sweep portion 115ie, the large inner diameter cylindrical surface 115if, and the third truncated conical inner surface 115ig form a loose-fitting surface that allows axial movement of the tip 114 and / or the tip holder 113 without abutting against the tip 114 and / or the tip holder 113.

[0093] Furthermore, the first truncated conical inner surface 115ib, which is part of the loose-fit surface, is adjacent to the rear side of the auxiliary truncated conical inner surface 115is (the rear region of the chip abutment surface) and forms a transition surface that tapers toward the front end and has a larger inclination angle than the tapered inclination angle of the auxiliary truncated conical inner surface 115is (the rear region of the chip abutment surface).

[0094] In addition, the annular member 115 of this embodiment is provided with three slits 115s as cutouts. As shown in Fig. 2(a) to Fig. 2(g), the three slits 115s are arranged at equal intervals (every 120°) in the circumferential direction of the annular member 115. Each of the three slits 115 has a width of 0.8 mm and extends in the axial direction of the annular member 115 from the front end to approximately the center of the second truncated cone outer surface 115d (maximum axial length: 5.5 mm).

[0095] As a result, when a load is applied to the first truncated cone outer surface 115b (abutment 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.

[0096] On the other hand, as shown in FIG. 4, the inner circumferential surface near the opening of the barrel 111 is provided with, in that 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.

[0097] As a result, the first truncated cone outer surface 115b (contact surface) receives loads from the first truncated cone inner surface 111ib and the second truncated cone inner surface 111id (guide surfaces) as the chip holder 113 moves toward the front end.

[0098] 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 operating portion 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 50 gf to 300 gf (about 0.49 N to 2.94 N). For example, the operating load when not in use (FIG. 1) is 68 gf, the load at full stroke (see FIG. 12) is 288 gf, and the operating load when writing (see FIG. 13) is 227 gf. The spring constant is 0.23 N / mm.)

[0099] The retractable writing instrument 110 configured as above operates as follows.

[0100] 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).

[0101] 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.

[0102] In the state of Fig. 4, 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, the first truncated cone outer surface 115b (contact surface) receives a load from the first truncated cone inner surface 111ib (guide surface), and the presence of the three slits 15s of the annular member 115 reduces the inner diameter of the annular member 115 (if the 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).

[0103] The inner diameter when the diameter is reduced (in the state of FIG. 4) 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 effect 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 effect. 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 effect. This can improve the convenience of the user.

[0104] Here, if the above-mentioned creep occurs, the inner diameter at the time of this diameter reduction (in the state of FIG. 4) may become smaller than the original desired value (the degree of diameter reduction may become large). In the embodiment described in Patent Document 5, in such a case, there is a risk that the user may feel an unpleasant resistance when operating the tip to protrude. In contrast, according to this embodiment, an auxiliary truncated cone inner surface 115is (a rearward region of the tip abutment surface) for tip abutment guide is provided between the small inner diameter cylindrical surface 115ia (a frontward region of the tip abutment surface) and the first truncated cone inner surface 115ib (a transition surface that is a part of the loose-fitting surface), so that the resistance when the tip 114 starts to abut against the tip abutment surface can be significantly reduced.

[0105] According to the knowledge of the present inventors, the inclination angle of the auxiliary truncated cone inner surface 115is (the rear region of the tip abutment surface) is preferably about 7° to 9°. Also, the axial length of the auxiliary truncated cone inner surface 115is (the rear region of the tip abutment surface) is preferably about 1.0 mm to 2.0 mm.

[0106] 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.

[0107] 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. 12), and when the tip protruding operation is finished (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 state protruding for writing (generally the same state as in FIG. 13). 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).

[0108] Here, even if the stopper element that determines the forward movement limit of the annular member 115 functions, if 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 (if the diameter difference is about 0.05 mm or more: see paragraph 0103), 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, so that it is guaranteed that the tip 114 will be effectively gripped 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.

[0109] 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 12), 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 4.

[0110] 1, the tip holder 113 is moved rearward, and the load that the first truncated cone outer surface 115b (contact surface) received from the first truncated cone inner surface 111ib (guiding 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 state reduced in diameter due to creep).

[0111] During the above-described process of the tip extension and retraction operation, the contact surface of the annular member 115 (first truncated cone outer surface 115b) and the guide surface of the barrel 111 (first truncated cone inner surface 111ib) are always in contact with each other.

[0112] 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 (first truncated cone outer surface 115b) 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. As a result, the barrel 111 and the annular member 115 work together to hold the tip 114 without any rattling (play).

[0113] Furthermore, according to the retractable writing instrument 110 of this embodiment, the auxiliary truncated cone inner surface 115is (the rear region of the tip abutment surface) is tapered toward the front end, thereby significantly reducing the resistance when the tip 114 begins to abut against the tip abutment surface (the small inner diameter cylindrical surface 115ia and the auxiliary truncated cone inner surface 115is).

[0114] In particular, according to the retractable writing instrument 110 of this embodiment, the auxiliary truncated cone inner surface 115is (the rear region of the tip abutment surface) is a truncated cone surface, so that the resistance when the tip 114 starts to abut against the tip abutment surface can be more effectively reduced. However, at least at the time of filing this application, an embodiment in which a convex curved surface (with a cross-sectional curvature radius of, for example, 1 mm to 4 mm) that is tapered toward the front end and rotationally symmetric about the axis is provided instead of the auxiliary truncated cone inner surface 115is, which is a truncated cone surface, is also included within the scope of the present invention.

[0115] Furthermore, 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 0103), 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.

[0116] 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.

[0117] In addition, since the contact surface (first truncated cone outer surface 115b) of the annular member 115 and the guide surface (first truncated cone inner surface 111ib) of the barrel 111 are the corresponding truncated cone outer surface and 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 (first truncated cone outer surface 115b) of the annular member 115 and the guide surface (first truncated cone inner surface 111ib) of the barrel 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.

[0118] 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.

[0119] 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).

[0120] Furthermore, according to the retractable writing implement 110 of this embodiment, the tip abutment portion (the small inner diameter cylindrical surface 115ia and the auxiliary truncated cone inner surface 115is) of the annular member 115 that grips the tip 114 is located forward of the abutment surface (the first truncated cone outer surface 115b) of the annular member 115 (there is no tip abutment portion radially inward of the abutment surface). This allows the tip 114 to be gripped further forward, and the tip 114 to be gripped more effectively without any rattling (play).

[0121] 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.

[0122] Furthermore, according to the retractable writing instrument 110 of this embodiment, the contact surface (first truncated cone outer surface 115b) 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 each other and separating from each other every time the tip 114 is retracted, resulting in stable operation and a smooth operation feeling for the user (no sense of discomfort).

[0123] 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.

[0124] 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.

[0125] 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.

[0126] <Second embodiment> In the first embodiment, as described with reference to Figures 2(e) and 3, the inner surface of the annular member 115 is provided with, in this order from the front side, a small inner diameter cylindrical surface 115ia, an auxiliary truncated conical inner surface 115is, a first truncated conical inner surface 115ib, a medium inner diameter cylindrical surface 115ic, a second truncated conical inner surface 115id, a four-sided portion 115ie, a large inner diameter cylindrical surface 115if, and a third truncated conical inner surface 115ig.

[0127] Here, a R chamfer may be provided in the connection region (boundary) between the auxiliary truncated cone inner surface 115is and the first truncated cone inner surface 115ib, which can more effectively reduce the resistance when the tip 114 starts to abut against the tip abutment surface, particularly when the tip 114 is positioned offset in any radial direction (smoother insertion can be achieved because there is less catching).

[0128] Figures 5 and 6 are diagrams showing such a second embodiment of the present invention. More specifically, Figure 5 is an enlarged cross-sectional view (corresponding to Figure 3) of an annular member 215 of a retractable writing instrument 210 according to the second embodiment of the present invention, and Figure 6 is a schematic vertical cross-sectional view (corresponding to Figure 4) for explaining the operation of the retractable writing instrument 210 according to the second embodiment of the present invention.

[0129] As shown in FIG. 5, the inner peripheral surface of the annular member 215 is made up of, from the front side, a small inner diameter cylindrical surface 215ia (φ3.0 mm, axial length 0.2 mm) (at least the rear side region of the tip contact surface), an auxiliary truncated cone inner surface 215is for tip contact and guide (inclination angle of about 8°, axial length 1.2 mm), an R-chamfered portion 215ir (cross-sectional curvature radius of 1 mm (preferably about 0.5 mm to 4 mm), axial length 0.4 mm), and a first truncated cone inner surface 215ib (inclination angle of about 30°, axial length The inner diameter cylindrical surface 215i (inscribed circle φ5.28 mm, axial length 0.9 mm) is provided in this order, as is a first truncated conical surface 215i (φ3.6 mm, axial length 3.9 mm) (which may be a truncated conical surface with a gentle inclination angle instead of a cylindrical surface), a second truncated conical inner surface 215i (axial length 0.4 mm), a four-sided chamfered portion 215i (inscribed circle φ5.28 mm, axial length 0.9 mm), a large inner diameter cylindrical surface 215i (φ5.43 mm, axial length 2.1 mm), and a third truncated conical inner surface 215i (axial length 0.4 mm).

[0130] That is, compared with the first embodiment, the auxiliary truncated conical inner surface 215is is a portion having an axial length of 1.8 mm in front of the auxiliary truncated conical inner surface 115is, the first truncated conical inner surface 215ib is a portion having an axial length of 0.8 mm behind the first truncated conical inner surface 115ib, and the R chamfered portion 215ir is provided in place of the portion having an axial length of 1.8 mm behind the auxiliary truncated conical inner surface 115is and the portion having an axial length of 0.8 mm in front of the first truncated conical inner surface 115ib.

[0131] The small inner diameter cylindrical surface 215ia and the auxiliary truncated conical inner surface 215is form a tip abutment surface that abuts against the periphery of the tip 114 when the inner diameter of the annular member 215 decreases as the tip holder 113 moves toward the front end. The small inner diameter cylindrical surface 215ia is a front region of the tip abutment surface, and the auxiliary truncated conical inner surface 215is is a rear region of the tip abutment surface.

[0132] In addition, the R-chamfered portion 215ir, the first truncated conical inner surface 215ib, the medium inner diameter cylindrical surface 215ic, the second truncated conical inner surface 215id, the four-sided cut portion 215ie, the large inner diameter cylindrical surface 215if, and the third truncated conical inner surface 215ig form a loose fit surface that allows axial movement of the tip 114 and / or the tip holder 113 without abutting against the tip 114 and / or the tip holder 113.

[0133] Furthermore, the first truncated conical inner surface 215ib, which is part of the loose-fit surface, is adjacent to the auxiliary truncated conical inner surface 215is (the rear region of the chip abutment surface) on the rear side via the R chamfered portion 215ir, and forms a tapered transition surface that tapers toward the front end and has a larger inclination angle than the tapered inclination angle of the auxiliary truncated conical inner surface 215is (the rear region of the chip abutment surface).

[0134] Furthermore, the annular member 215 of this embodiment is provided with three slits 215s as cutouts. As shown in Fig. 5(a) to Fig. 5(g), the three slits 215s are arranged at equal intervals (every 120°) in the circumferential direction of the annular member 215. Furthermore, each of the three slits 215 has a width of 0.8 mm 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).

[0135] As a result, when a load is applied to the first truncated cone outer surface 215b (contact surface), the inner diameter of the annular member 215 flexibly shrinks, and when the load is released, the inner diameter of the annular member 215 elastically returns to its original state.

[0136] Other configurations of the second embodiment are substantially the same as those of the first embodiment described with reference to Figures 1 to 4. In Figures 5 and 6, the same parts as those of the first embodiment are denoted by the same reference numerals. Further, detailed description of the same parts of this embodiment as those of the first embodiment will be omitted.

[0137] The retractable writing instrument 210 of the second embodiment also operates in the following manner, similar to the retractable writing instrument 110 of the first embodiment.

[0138] When not in use, the tip 114 (writing body) of the retractable writing instrument 210 is in a retracted state (see 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 215 is not contracted, and the small inner diameter cylindrical surface 215ia of the annular member 215 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 becomes longer than 17 mm, the annular member 215 has already contracted, and the small inner diameter cylindrical surface 215ia of the annular member 215 becomes smaller than φ3.0 (it may maintain a range larger than the outer diameter of the tip 114, or it may become smaller than the outer diameter of the tip 114).

[0139] 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 210 reaches the state shown in FIG.

[0140] 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 215 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, the first truncated cone outer surface 215b (contact surface) receives a load from the first truncated cone inner surface 11ib (guide surface), and the three slits 215s of the annular member 215 reduce the inner diameter of the annular member 215 (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).

[0141] 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 effect 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 215 can provide a similarly effective anti-vibration effect. That is, the retractable writing instrument 210 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.

[0142] Here, if the above-mentioned creep occurs, the inner diameter at the time of this diameter reduction (in the state of FIG. 6) may become smaller than the original desired value (the degree of diameter reduction may become large). In the embodiment described in Patent Document 5, in such a case, there is a risk that the user may feel an unpleasant resistance when operating the tip to protrude. In contrast, according to this embodiment, an auxiliary truncated cone inner surface 215is (a rearward region of the tip abutment surface) for tip abutment guide is provided between the small inner diameter cylindrical surface 215ia (a frontward region of the tip abutment surface) and the first truncated cone inner surface 215ib (a transition surface that is a part of the loose-fitting surface), so that the resistance when the tip 114 starts to abut against the tip abutment surface can be significantly reduced.

[0143] Furthermore, according to this embodiment, an R-chamfered portion 215ir is provided between the auxiliary truncated cone inner surface 215is (the rear end region of the tip abutment surface) and the first truncated cone inner surface 215ib (transition surface), thereby more effectively reducing the resistance when the tip 114 begins to abut against the tip abutment surface (the small inner diameter cylindrical surface 215ia and the auxiliary truncated cone inner surface 215is), particularly in cases where the position of the tip 114 is biased in any radial direction.

[0144] <Further Variation 1> Although not shown, as a modified example of the second embodiment, the auxiliary truncated cone inner surface 215is (the rear end region of the tip abutment surface), the R chamfered portion 215ir, and the first truncated cone inner surface 215ib (the transition surface) may be configured as an integral R chamfered portion (whose curvature may be constant or may change midway) (the auxiliary truncated cone inner surface 215is and the first truncated cone inner surface 215ib are replaced by the chamfered portion). In this case, too, the resistance when the tip 114 starts to abut against the tip abutment surface can be more effectively reduced (there is less catching, so smoother insertion can be achieved).

[0145] <Further variation 2> Although not shown in the drawings, in each of the above embodiments, a R chamfer may be provided at the connection region (boundary) between the small inner diameter cylindrical surface 115ia, 215ia and the auxiliary truncated cone inner surface 115is, 215is. This is expected to further effectively reduce the resistance caused by the contact or sliding of the tip 114 against the tip contact surface.

[0146] <Further Variation 3> In each of the above embodiments, the tip 114 is illustrated as being of a type in which the conical portion 114a and the cylindrical portion 114b are adjacent to each other via a ridge-like connection region (see FIG. 7(a)). However, if instead a type in which the conical portion 114a' and the cylindrical portion 114b' are adjacent to each other via an R-chamfered portion 114r' is used (see FIG. 7(b)), it is expected that the resistance associated with the contact or sliding of the tip 114' against the tip contact surface can be further effectively reduced.

[0147] (Additional information about refills) The retractable writing instrument 110, 210 of each of the above embodiments is a writing instrument comprising a barrel 111, a refill (writing body) contained in the barrel 111, 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.

[0148] An example of a refill will be further described with reference to Figures 14 to 16. Referring to Figure 14, the refill 6 includes, for example, a pen tip (tip) 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.

[0149] 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.

[0150] (Additional information regarding the rear end of the barrel 111) The shaft tube 111 of this embodiment comprises, for example, a tapered cylindrical front shaft 3 (see FIG. 17), a cylindrical intermediate shaft 4 (see FIG. 18) connected to the rear end of the front shaft 3, and a cylindrical rear shaft 5 (see FIG. 19) connected to the rear end of the intermediate shaft 4.

[0151] 19, 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 integrally formed on the inner surface of the rear axle 5.

[0152] 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.

[0153] The elastic synthetic resin constituting the friction portion 53 is preferably made of a low-wear elastic material that generates almost no 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 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 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 or the entire rear axle 5 can be integrally formed from an elastic material.

[0154] (Additional information about knock member 8) 20, 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.

[0155] 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.

[0156] As shown in FIG. 20, 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. 21 to 24).

[0157] 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).

[0158] 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 tube 111. In addition, the front shaft 3 and the intermediate shaft 4 are detachably connected by screwing, so that the refill 6 can be replaced at any time.

[0159] (Additional information about 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 aforementioned 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 each time the knock member 8 is moved forward, and rotates the refill 6 (and therefore the nib 61), the aforementioned cam portion 43 that is provided within the barrel 111 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 and urges the refill 6 rearward.

[0160] 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.

[0161] (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.

[0162] 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.

[0163] (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, and the refill 6 (and therefore the pen tip 61) is rotated. Writing instruments in which the pen tip 61 rotates in this manner are popular on the market because they can even out wear on the pen tip 61.

[0164] Fig. 25 is a schematic diagram for explaining the principle of the rotating cam mechanism. Referring to Fig. 25, when the knock member 8 is pressed (slid) forward from the pen tip retracted state (see Fig. 25(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.

[0165] 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 is caused to protrude to the outside through the opening of the barrel 111.

[0166] 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 25(b)).

[0167] 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. 25(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.

[0168] Next, when the knock member 8 is pushed (slid) forward from the pen tip extended state (see Figure 25c), 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.

[0169] 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. 25(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. 25(a)).

[0170] 26 and 27 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.

[0171] 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.

[0172] 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.

[0173] (Additional information regarding rotation of the annular members 115 and 215) When the refill 6 is rotated relative to the barrel 111 by the pressing operation of the knock member 8, the annular members 115 and 215 connected to the refill 6 via the coil spring 116 are also rotated relative to the barrel 111.

[0174] At this time, the front end of the coil spring 116 is fixed to the annular members 115 and 215. As a result, the front end of the coil spring 116 does not slide on the inner surface of the annular members 115 and 215, so there is no risk of the front end damaging the annular members 115 and 215. In addition, the annular members 115 and 215 connected to the refill 6 via the coil spring 116 are also rotated relative to the barrel 111, so that the refill 6 and the coil spring 116 can rotate together. As a result, the rear end of the coil spring 116 does not slide on the tip holder 113, so there is no risk of the rear end damaging the tip holder 113. In addition, the refill 6, the annular members 115 and 215, 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 members 115, 215 is visible, it is possible to provide visual interest to the user.

[0175] (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. 1).

[0176] 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 will result in a strong connection between the tip holder 113 and the coil spring 116 (for example, the two will be hooked together), making it easier for the coil spring 116 to transmit the rotational force of the refill 6 to the annular members 115, 215, which is preferable.

[0177] FIG. 28 is a view corresponding to FIG. 1, in which the winding direction of the coil spring 16 is reversed.

[0178] Here, it is further preferable that the coil spring abutment portion of chip holder 113 be provided with an uneven shape or the like so as to make the connection with the rear end of coil spring 116 stronger.

[0179] (Other aspects of the notch) In the above-described embodiment, the slits 115s, 215s are provided as the cutouts. That is, the cutouts are formed to penetrate the annular members 115, 215 from the inner periphery to the outer periphery.

[0180] However, the cutout is not limited to such a configuration, and may be formed as a portion that is thinner than the surroundings (a configuration in which a part of the thickness is cut out). For example, a configuration in which a thin portion remains at the portion of slits 115s and 215s may be adopted.

[0181] FIG. 18(a) is an oblique view of such a modified annular member 15″, FIG. 18(b) is a plan view of the annular member 15″ of FIG. 18(a), FIG. 18(c) is a side view of the annular member 15″ of FIG. 18(a), FIG. 18(d) is a bottom view of the annular member 15″ of FIG. 18(a), FIG. 18(e) is a cross-sectional view taken along line AA of FIG. 18(c), FIG. 18(f) is a front view (viewed from the tip side) of the annular member 15″ of FIG. 18(a), and FIG. 18(g) is a rear view of the annular member 15″ of FIG. 18(a).

[0182] As shown in Figures 18(a) to 18(g), the outer peripheral surface of the annular member 15" is provided with, in this order from the front side, a small outer diameter cylindrical surface 15a", a first truncated conical outer surface 15b" as a tapered abutment surface, a medium outer diameter cylindrical surface 15c", a second truncated conical outer surface 15d" as a tapered abutment surface, a first large outer diameter cylindrical surface 15e", a third truncated conical outer surface 15f" as a tapered abutment surface, and a second large outer diameter cylindrical surface 15g".

[0183] The annular member 15" of this modified example is provided with three thin-walled portions 15t" as cutouts. As shown in Figures 18(a) to 18(g), the three thin-walled portions 15t" are arranged at positions corresponding to the three slits 115s, 215s, i.e., at equal intervals (every 120°) in the circumferential direction of the annular member 15". Each of the three thin-walled portions 15t" has a width of 0.8 mm and a thickness of 0.2 mm, and extends from the front end to approximately the center of the second truncated cone outer surface 15d" in the axial direction of the annular member 15" (maximum axial length: 5.5 mm).

[0184] Even in such a modified example, when a load is applied to the first frusto-conical outer surface 15b'' (contact surface), the inner diameter of the annular member 15'' can flexibly contract, and when the load is released, the inner diameter of the annular member 15'' can elastically return to its original state. [Explanation of symbols]

[0185] 10 Retractable writing instrument (Patent Document 5) 11 Shaft cylinder 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 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 (first embodiment) 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 114a Cone 114b Cylindrical part 114' Chip (Modified) 114a' Cone 114r' R chamfer 114b' Cylindrical section 115 Annular member 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 115ia Small inner diameter cylindrical surface 115is Auxiliary truncated cone inner 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 210 Retractable writing instrument (second embodiment) 215 Annular Members 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 215is Auxiliary truncated cone inner surface 215ir R chamfered part 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 215s Slit 15” Circular Member 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” 3rd truncated cone outer surface 15g” Second large outer diameter cylindrical surface 15t” thin section 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 tube 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 tip contact surface is formed on an inner periphery of the annular member on the front side thereof, the tip contact surface being adapted to contact the periphery of the tip when the inner diameter of the annular member is reduced as the tip holder moves toward the front end side; a loose fitting surface is formed on an inner periphery of the rear side of the annular member, the loose fitting surface allowing the tip and / or the tip holder to move in the axial direction without contacting the tip and / or the tip holder; At least a rear region of the tip contact surface is tapered toward a front end. A retractable writing instrument characterized by:

2. At least the rear region of the tip contact surface has a frusto-conical surface.

2. The retractable writing instrument according to claim 1 .

3. At least a rear end region of the tip contact surface is provided with a rounded chamfer.

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

4. a transition surface is formed adjacent to the tip contact surface on the rear side thereof, the transition surface being tapered toward a front end thereof at an angle greater than an angle of inclination of the tapered tip contact surface in at least the rear region thereof; A rounded chamfer is provided between at least the rear end region of the tip contact surface and the transition surface.

4. The retractable writing instrument according to claim 3.

5. The front region of the tip contact surface is a cylindrical surface or a substantially cylindrical surface.

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

6. The entire tip contact surface is tapered toward the front end.

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

7. A stopper element provided on the barrel and / or the annular member to define a rearward movement limit of the annular member 3. The retractable writing instrument according to claim 1 or 2, further comprising:

8. A plurality of the notches are disposed at equal intervals in the circumferential direction of the annular member, Each of the plurality of notches is a slit extending in the axial direction of the annular member.

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

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

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

10. The abutment surface has a frustoconical surface.

10. The retractable writing instrument according to claim 9.

11. The elastic member is a coil spring.

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

12. 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.

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

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

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

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

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

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

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

16. 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, The annular member is adapted to rotate relative to the barrel every time the knock member is moved forward.

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

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