JP7628426B2 - Retractable writing implement - Google Patents

Description

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

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.

Patent Document 2 also discloses a device for preventing the writing tip from shaking. The device is configured so that an elastic ring with an inner diameter slightly smaller than the outer diameter of the writing tip is engaged with a locking step provided inside the tip of the barrel. With this device, because the elastic ring locks the writing tip, 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 when writing.

Patent Document 3 discloses a writing implement that slides back and forth relative to a barrel to advance the writing part of a writing body from an opening in the barrel. An annular member is disposed on the outer periphery of the tip of the writing body, and a roughly spherical inner surface against which the annular member abuts is formed on the inner surface around the opening at the tip of the barrel from which the writing part emerges. The annular member is fixed to the writing body via a spring and is biased forward. When the writing part is advanced, the elastic force of the spring causes the annular member to adhere closely to the inner surface of the tip of the barrel. This makes it possible to prevent rattling when writing.

Patent Document 4 by the present applicant discloses four types of configurations for retractable writing instruments that prevent tip wobble.

<First Type of Patent Document 4>
Fig. 11 is a schematic vertical cross-sectional view of the retractable writing instrument 110 of the first type of Patent Document 4, showing a state in which the tip 114 (writing body) is not protruding. Fig. 12(a) is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument 110 of the first type, and Fig. 12(b) is a cross-sectional view taken along line A-A in Fig. 12(a). Fig. 13(a) is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument 110 of the first type in a state in which the tip 114 (writing body) is protruding, and Fig. 13(b) is a cross-sectional view taken along line B-B in Fig. 13(a).

In addition, Figure 14(a) is a perspective view of the annular member 115 of the first type of retractable writing instrument 110, Figure 14(b) is a side view of the annular member 115, Figure 14(c) is a cross-sectional view taken along line C-C of Figure 14(b), Figure 14(d) is a front view of the annular member 115 (viewed from the tip side), and Figure 14(e) is a rear view of the annular member 115.

Furthermore, Figure 15 is a schematic diagram showing the state in which the tip holder 113 has been pulled out for replacement or the like in the first type of retractable writing instrument 110.

The first type of retractable writing instrument 110 shown in Figures 11 to 15 has a cylindrical barrel 111 with an opening at the front end. As shown in Figures 11 to 13, the barrel 111 of the first type has a rear portion 111a, an inner barrel portion 111b, a front portion 111c, and a ferrule portion 111d, and the rear portion 111a and the inner barrel portion 111b are removably fixed by a screw connection (screw engagement), and the inner barrel portion 111b and the front portion 111c are integrally formed by two-color molding. On the other hand, the ferrule portion 111d is removably fixed to the inner barrel portion 111b by a screw connection (screw engagement).

A tip holder 113 that can move 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. As the tip holder 113 moves, the tip 114 can appear and disappear from the opening of the barrel 111, as shown in Figures 12(a) and 13(a).

As shown in FIG. 15, the tip holder 113 has, in this order from the base end to the tip end, a base end 113a, a first collar portion 113b, a second collar portion 113c, a spring fixing auxiliary portion 113f, and a tip end 113d. The base end 113a, the first collar portion 113b, the second collar portion 113c, the spring fixing auxiliary portion 113f, and the tip end 113d are all cylindrical portions, and the relationship between their cross-sectional diameters is base end 113a > first collar portion 113b > second collar portion 113c > spring fixing auxiliary portion 113f > tip end 113d.

As shown in FIG. 12(b) in particular, a resin or metal annular member 115 is loosely fitted around the outer periphery of the tip 113d of the chip holder 113. The annular member 115 is fixed to the second collar portion 113c of the chip holder 113 via a coil spring 116 (an example of an elastic member) that similarly surrounds the outer periphery of the tip 113d of the chip holder 113 in a loosely fitted state (with a small gap). This allows the annular member 115 to move in the axial direction of the chip holder 113 relative to the tip 113d of the chip holder 113 as the coil spring 116 expands and contracts, as shown in FIG. 12(a) and FIG. 13(a).

The chip holder 113 is provided with a spring fixing auxiliary portion 113f to assist in fixing the coil spring 116 to the second collar portion 113c.

As shown in Figs. 14(a) to 14(e), a truncated cone-shaped abutment surface 115t is formed in the front region of the outer periphery of the annular member 115 as a tapered abutment surface toward the front end. A large outer diameter cylindrical portion 115a is provided continuously to the rear of the abutment surface 115t, and a small outer diameter cylindrical portion 115b is provided further behind the abutment surface 115t via a step.

The annular member 115 has four slits 115s as notches. As shown in Figures 14(a) to 14(e), the four slits 115s are arranged at equal intervals (every 90°) around the circumference of the annular member 115. Each of the four slits 115s extends from the front end to approximately the center of the small diameter cylindrical portion 115b in the axial direction of the annular member 115. This allows the inner diameter of the annular member 115 to flexibly contract when a load is applied to the contact surface 115t, and allows the inner diameter of the annular member 115 to elastically return to its original shape when the load is released.

As shown in Figures 12(a) and 13(a), a guide surface 111t in the shape of a concave truncated cone is formed on part of the inner surface of the base portion 111d of the barrel 111 as a guide surface tapering toward the front end. As a result, the abutment surface 115t is adapted to receive a load from the guide surface 111t as the tip holder 113 moves toward the front end (Figure 12(a) → Figure 13(a)).

The first type of retractable writing implement 110 is also provided with a second coil spring 112 (second elastic member) for automatically retracting the tip holder 113 when the tip 114 is retracted (for example, by pressing a push button provided at the rear end of the writing implement to release the locking mechanism that maintains the tip 114 in a protruding state). The second coil spring 112 is inserted between a shoulder provided on the inner surface of the base portion 111d and the first collar portion 113b of the tip holder 113 so as to further surround the outer periphery of the coil spring 116.

The second coil spring 112 may be fixed to the inner surface of the base portion 111d, or may be free (not fixed to any member). Alternatively, it may be fixed to the first collar portion 113b of the tip holder 113.

The first type of retractable writing instrument 110 described above works as follows.

When not in use, the tip 114 (writing body) of the retractable writing instrument 110 is in a retracted state as shown in FIG. 12(a). At this time, the axial length of the coil spring 116 is 8.2 mm, and the axial length of the second coil spring 112 is 16.4 mm. Then, when the tip is protruded (for example, by pressing a push button provided at the rear end of the writing instrument), the tip 114 (writing body) of the retractable writing instrument 110 becomes in a protruding state as shown in FIG. 13(a). Normally, 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 5.6 mm (compressed 2.6 mm), and the axial length of the second coil spring 112 is 9.4 mm (compressed 7.0 mm).

In the process of moving from the retracted state of FIG. 12(a) to the extended state of FIG. 13(a), as the chip holder 113 moves toward the front end, the contact surface 115t of the annular member 115 receives a load from the guide surface 111t of the nozzle portion 111d. At this time, the four slits 115s in the annular member 115 reduce the inner diameter of the annular member 115 (FIG. 12(b) → FIG. 13(b)). As a result, as shown in FIG. 13(b), the nozzle portion 111d and the annular member 115 work together to grip the tip portion 113d of the chip holder 113 without any rattling (play).

Furthermore, since the chip holder 113 and the annular member 115 are connected by the coil spring 116 so as to be movable relative to each other, it is possible to ensure that the tip 113d of the chip holder 113 is effectively gripped without any rattling (play) even without highly accurate dimensional control over the degree of reduction in the inner diameter of the annular member 115.

After that, when the tip is retracted (for example, by pressing the push button at the rear end of the writing instrument again), a locking mechanism (not shown), for example, is released, and the tip 114 (writing body) of the retractable writing instrument 110 returns to the retracted state shown in FIG. 12(a) by the action of the second coil spring 112.

In the process of going from the protruding state of FIG. 13(a) to the retracted state of FIG. 12(a), the load that the contact surface 115t of the annular member 115 received from the guide surface 111t of the nozzle portion 111d disappears as the tip holder 113 moves toward the rear end side. As a result, the inner diameter of the annular member 115, which had been reduced, returns to its original state (FIG. 13(b) → FIG. 12(b)).

<Second Type of Patent Document 4>
Fig. 16 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument 120 of the second type in Patent Document 4, and Fig. 17 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument 120 of the second type in a state in which the tip 124 (writing body) is protruding. Furthermore, Fig. 18 is a schematic view showing a state in which the tip holder 123 (base end portion 123a, first collar portion 123b, second collar portion 123c, and tip portion 123d) is pulled out for replacement or the like in the retractable writing instrument 120 of the second type.

The second type of retractable writing instrument 120 has a cylindrical resin spring portion 126e instead of the coil spring 116 in the first type of retractable writing instrument 110. The resin spring portion 126e has six pairs of approximately semicircular slits that face each other vertically and six pairs of approximately semicircular slits that face each other horizontally, alternately arranged in the axial direction. This allows the resin spring portion 126e to expand and contract in the axial direction.

The resin spring portion 126e is molded integrally with the annular member 125. The annular member 125 has four slits 125s as cutouts, similar to the annular member 115 of the first type of retractable writing instrument 110.

The second type of retractable writing instrument 120 also provides substantially the same effect as the first type of retractable writing instrument 110. That is, the base portion 111d and the annular member 125 (contact surface 125t) work together to hold the tip portion 123d of the tip holder 123 without any rattling (play).

<Third Type of Patent Document 4>
Fig. 19 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument 130 of the third type in Patent Document 4, and Fig. 20 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument 130 of the third type in a state in which the tip 134 (writing body) is protruding. Furthermore, Fig. 21 is a schematic view showing a state in which the tip holder 133 (base end portion 133a, middle collar portion 133m and tip portion 133d) is pulled out for replacement or the like in the retractable writing instrument 130 of the third type.

The third type of retractable writing instrument 130 is obtained by fixing a collar member 132 (first collar portion 133b and second collar portion 133c) to the rear end of the coil spring 112 (second elastic member) of the first type of retractable writing instrument 110, and fixing the rear end of the coil spring 116 (elastic member) whose front end is connected to the annular member 115 to the collar member 132 instead of the second collar portion 113c of the tip holder 113.

The third type of retractable writing instrument 130 also provides substantially the same effect as the first type of retractable writing instrument 110. That is, the ferrule portion 111d and the annular member 115 work together to hold the tip portion 133d of the tip holder 133 without any rattling (play).

In addition, with the third type of retractable writing instrument 130, there is no need to provide the annular member 115 on the tip holder 133, so existing replacement refills with conventional tip holders can also be used.

<Fourth Type of Patent Document 4>
Fig. 22 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument 140 of the fourth type in Patent Document 4, and Fig. 23 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument 140 of the fourth type in a state in which the tip 144 (writing body) is protruding. Furthermore, Fig. 24 is a schematic view showing a state in which the tip holder 143 (base end portion 143a, middle collar portion 143m and tip portion 143d) is pulled out for replacement or the like in the retractable writing instrument 140 of the fourth type.

The fourth type of retractable writing instrument 140 is obtained by fixing a collar member 142 (first collar portion 143b and second collar portion 143c) to the rear end of the resin spring portion 126 (second elastic member) of the second type of retractable writing instrument 120, and fixing the rear end of the resin spring portion 126 (elastic member) whose front end is integrated with the annular member 125 to the collar member 142 instead of the second collar portion 123c of the tip holder 123.

The fourth type of retractable writing instrument 140 also provides substantially the same effect as the second type of retractable writing instrument 120. That is, the base portion 111d and the annular member 125 work together to hold the tip portion 143d of the tip holder 143 without any rattling (play).

In addition, with the fourth type of retractable writing instrument 140, there is no need to provide the annular member 125 on the tip holder 143, so existing replacement refills with conventional tip holders can also be used.

Japanese Utility Model Application Publication No. 5-85683 Japanese Utility Model Application Publication No. 5-93884 Patent Publication 2013-220602 Patent Publication 2019-111657

The technology disclosed in Patent Documents 1 and 2 is insufficient in preventing rattling because the O-ring can deform in the radial direction. In addition, the writing part may get stuck on the surface of the O-ring, making it impossible to smoothly retract the extended writing part.

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 creates problems in terms of productivity.

In addition, in the first and fourth types of configurations of Patent Document 4, two types of coil springs 112, 116 are used in combination, and these coil springs 112, 116 may get caught on each other during assembly or refill replacement, which may impair the smoothness of the work. Furthermore, when the coil springs 112, 116 contract as the tips 113, 143 extend and retract, there is a risk that these coil springs 112, 116 may get tangled and cause malfunctions.

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) of the resin spring portion 126, so the degree of design freedom is low.

The present invention was made in light of the above findings, and its purpose is to provide a retractable writing instrument that prevents the tip from wobbling when writing, providing a stable writing feel, while reducing the risk of malfunction.

The present invention is a retractable writing instrument that includes a barrel having an opening at the front end, a tip holder that is housed inside the barrel and can move in the axial direction of the barrel, a tip that is fixed to the front end of the tip holder and can be inserted and removed from the opening of the barrel as the tip holder moves, an annular member that is loosely fitted into the inner circumference of the opening of the barrel and can move in the axial direction of the barrel relative to the barrel, and an elastic member that connects the barrel and the annular member so that they can move relative to each other, and at least a part of the outer circumference of the annular member is formed with an abutment surface that abuts against a part of the inner surface of the opening of the barrel, 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 applied to the abutment surface, and a guide surface is formed on a part of the inner surface of the opening of the barrel against which the abutment surface abuts as the annular member moves toward the rear end.

According to the present invention, as the annular member moves toward the rear end, 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. This allows the barrel and the annular member to cooperate to grip the tip or tip holder without any rattle (play). In addition, because the barrel and the annular member are connected by an elastic member so that they can move relative to each other, it is possible to ensure that the tip or tip holder is effectively gripped without any rattle (play) even without highly accurate dimensional control over the degree of reduction in the inner diameter of the annular member.

Preferably, the annular member moves toward the front end together with the chip holder while elastically deforming the elastic member as the chip holder moves toward the front end, and then moves toward the rear end due to the restoring force of the elastic member as the chip holder moves toward the rear end, and the abutment surface receives the load from the guide surface as the annular member moves toward the rear end. In this case, it is possible to ensure that the chip or chip holder is effectively gripped without rattle (play) in response to the retraction and projection of the chip holder using, for example, a "knock spring."

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

The abutment surface is preferably tapered toward the rear end. The abutment surface preferably has, for example, a truncated cone surface. In this case, the guide surface is preferably a corresponding concave cylindrical surface or a concave truncated cone surface. Alternatively, the abutment surface preferably has a convex curved surface that is rotationally symmetric about the axis. In this case, the guide surface is preferably 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.

Also, preferably, the elastic member is a coil spring.

In addition, preferably, when the tip is inserted, the contact surface and the guide surface are always in contact with each other. In this case, the annular member and the inner surface of the barrel do not separate, so rattling caused by vibration can be suppressed.

Moreover, preferably, the annular member protrudes forward from the opening of the barrel. In this case, the tip or tip holder can be gripped over a longer range, ensuring that the tip or tip holder is gripped more effectively without rattling (play).

Preferably, a soft member is provided on the operating section for extending and retracting the tip, or on the rear of the barrel. When the conventional configuration is used in a thermochromic writing instrument, there is a risk that the vibration caused by rubbing the writing may cause the tip or tip holder to rattle, generating noise, but this risk does not occur with the configuration of the present invention. Therefore, it is recommended that the configuration of the present invention be used in a thermochromic writing instrument.

The present invention also covers only the barrel assembly for the retractable writing instrument described above. That is, the present invention is a barrel assembly for a retractable writing instrument that can accommodate a tip holder with a tip fixed to the front end so as to be movable in the axial direction, has an opening at the front end, and can cause the tip to protrude and retract from the opening as the tip holder moves, and is characterized in that it comprises an annular member that is loosely fitted into the inner circumference of the opening of the barrel and is movable in the axial direction of the barrel relative to the barrel, and an elastic member that connects the barrel and the annular member so as to be movable relative to each other, at least a part of the outer circumference of the annular member is formed with an abutment surface that abuts against a part of the inner surface of the opening of the barrel, 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, and a guide surface is formed in a part of the inner surface of the opening of the barrel against which the abutment surface abuts as the annular member moves toward the rear end side.

According to the present invention, as the annular member moves toward the rear end, 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. This allows the barrel and the annular member to cooperate to grip the tip or tip holder without any rattle (play). In addition, because the barrel and the annular member are connected by an elastic member so that they can move relative to each other, it is possible to ensure that the tip or tip holder is effectively gripped without any rattle (play) even without highly accurate dimensional control over the degree of reduction in the inner diameter of the annular member.

FIG. 2 is a schematic vertical cross-sectional view of a retractable writing instrument in one embodiment of the present invention, showing a state in which the tip (writing body) is not protruding. FIG. 2 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument of FIG. Fig. 3(a) is a perspective view of the annular member of the retractable writing instrument of Fig. 1. Fig. 3(b) is a side view of the annular member of Fig. 3(a). Fig. 3(c) is a bottom view of the annular member of Fig. 3(a). Fig. 3(d) is a cross-sectional view taken along line A-A of Fig. 3(b). Fig. 3(e) is a front view (viewed from the tip side) of the annular member of Fig. 3(a). Fig. 3(f) is a rear view of the annular member of Fig. 3(a). 2 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. 1 . FIG. 2 is a schematic diagram showing a state in which the tip holder comes into contact with the annular member during the tip protruding operation in the retractable writing instrument of FIG. 1 . FIG. FIG. 6 is a schematic vertical cross-sectional view of the entire retractable writing instrument in the state shown in FIG. 5 . 2 is a schematic diagram showing a state in which the tip of the retractable writing instrument of FIG. 1 is fully protruded during a tip protruding operation. FIG. FIG. 8 is a schematic vertical cross-sectional view of the entire retractable writing instrument in the state shown in FIG. 7 . 2 is a schematic diagram showing a state in which the tip is protruded in the retractable writing instrument of FIG. 1 after the tip protruding operation has been completed; FIG. FIG. 10 is a schematic vertical cross-sectional view of the entire retractable writing instrument in the state shown in FIG. 9 . FIG. 1 is a schematic vertical cross-sectional view of a retractable writing instrument of the first type in Patent Document 4, showing a state in which the tip (writing body) is not protruding. Fig. 12(a) is an enlarged vertical cross-sectional view of the tip portion of a first type of retractable writing instrument of Patent Document 4. Fig. 12(b) is a cross-sectional view taken along line AA of Fig. 12(a). Fig. 13(a) is an enlarged vertical cross-sectional view of the tip portion of the first type of retractable writing instrument of Patent Document 4 in a state where the tip (writing body) is protruding. Fig. 13(b) is a cross-sectional view taken along line B-B of Fig. 13(a). Fig. 14(a) is a perspective view of an annular member of a first type of retractable writing implement of Patent Document 4. Fig. 14(b) is a side view of the annular member of Fig. 14(a). Fig. 14(c) is a cross-sectional view taken along line CC of Fig. 14(b). Fig. 14(d) is a front view (view from the tip side) of the annular member of Fig. 14(a). Fig. 14(e) is a rear view of the annular member of Fig. 14(a). This is a schematic diagram showing the state in which the tip holder has been pulled out for replacement or the like in the first type of retractable writing instrument of Patent Document 4. 1 is an enlarged vertical cross-sectional view of a tip portion of a retractable writing instrument of the second type disclosed in Patent Document 4. FIG. This is an enlarged vertical cross-sectional view of the tip portion of a second type of retractable writing instrument of Patent Document 4 in a state in which the tip (writing body) is protruding. This is a schematic diagram showing the state in which the tip holder has been pulled out for replacement or the like in the second type of retractable writing instrument of Patent Document 4. 1 is an enlarged vertical cross-sectional view of a tip portion of a retractable writing instrument of the third type disclosed in Patent Document 4. FIG. This is an enlarged vertical cross-sectional view of the tip portion of a third type of retractable writing instrument of Patent Document 4 in a state in which the tip (writing body) is protruding. This is a schematic diagram showing the state in which the tip holder has been pulled out for replacement or the like in the third type of retractable writing instrument of Patent Document 4. 1 is an enlarged longitudinal cross-sectional view of a tip portion of a retractable writing instrument of the fourth type disclosed in Patent Document 4. FIG. This is an enlarged vertical cross-sectional view of the tip portion of a fourth type of retractable writing instrument of Patent Document 4 in a state in which the tip (writing body) is protruding. This is a schematic diagram showing the state in which the tip holder has been pulled out for replacement or the like in a fourth type of retractable writing instrument of Patent Document 4. FIG. FIG. 2 is a perspective view of the rear end portion of the refill. FIG. FIG. 2 is a longitudinal cross-sectional view of a front shaft of an exemplary barrel. FIG. 2 is a longitudinal cross-sectional view of an intermediate shaft of an exemplary barrel. FIG. 2 is a longitudinal cross-sectional view of an exemplary rear axle barrel. FIG. 2 is a vertical cross-sectional view of a knock member. FIG. FIG. FIG. This is a cross-sectional view of line CC in Figure 32.

The following describes an embodiment of the present invention with reference to the drawings.

Figure 1 is a schematic vertical cross-sectional view of a retractable writing instrument 10 according to one embodiment of the present invention, showing a state in which the tip 14 (writing body) is not protruding. Figure 2 is an enlarged vertical cross-sectional view of the tip portion of the retractable writing instrument 10 according to this embodiment.

FIG. 3A is a perspective view of the annular member 15 of the retractable writing instrument 10 of this embodiment.
Figure 3(b) is a side view of the annular member 15 in Figure 3(a), Figure 3(c) is a bottom view of the annular member in Figure 3(a), Figure 3(d) is a cross-sectional view along line A-A in Figure 3(b), Figure 3(e) is a front view (view from the tip side) of the annular member in Figure 3(a), and Figure 3(f) is a rear view of the annular member in Figure 3(a).

Furthermore, FIG. 4 is a schematic diagram showing the state in which the tip 14 contacts the annular member 15 during the tip 14 protruding operation in the retractable writing instrument 10 of this embodiment, FIG. 5 is a schematic diagram showing the state in which the tip holder 13 contacts the annular member 15 during the tip 14 protruding operation in the retractable writing instrument 10 of FIG. 1, FIG. 6 is a schematic vertical cross-sectional view of the entire retractable writing instrument 10 in the state of FIG. 5, FIG. 7 is a schematic diagram showing the state in which the tip 14 is most protruding during the tip 14 protruding operation in the retractable writing instrument 10 of this embodiment, FIG. 8 is a schematic vertical cross-sectional view of the entire retractable writing instrument 10 in the state of FIG. 7, FIG. 9 is a schematic diagram showing the state in which the tip 14 protrudes after the tip 14 protruding operation is completed in the retractable writing instrument 10 of this embodiment, and FIG. 10 is a schematic vertical cross-sectional view of the entire retractable writing instrument 10 in the state of FIG. 9.

The retractable writing instrument 10 of this embodiment has a cylindrical barrel 11 with an opening at the front end. As shown in FIG. 1, in this embodiment, the barrel 11 has a rear portion 11r and a front portion 11m. The rear portion 11r and the front portion 11m are removably fixed by a screw connection (screw engagement). However, the rear portion 11r and the front portion 11m may also be fixed by a fitting connection, or may be formed as one piece.

A tip holder 13 that can move 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 4 to 10.

As shown in FIG. 2, the tip holder 13 has, in this order from the base end to the tip end, a base end 13a, a first collar portion 13b, and a second collar portion 13c. In this embodiment, the base end 13a and the first collar portion 13b are both cylindrical portions, and the second collar portion 13c is a truncated cone portion, and the relationship between their cross-sectional diameters is base end 13a > first collar portion 13b > second collar portion 13c.

In this embodiment, as shown in FIG. 2, an annular member 15 that can move 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 enlarged outer and inner diameter, and covers the periphery of the tip 14 (φ2.5) without contacting it.

The annular member 15 is fixed to the rear end of a coil spring 16 (an example of an elastic member). The coil spring 16 surrounds the outer periphery of the annular member 15 in a loose fit (with a gap), and the front end of the coil spring 16 is fixed to the inner periphery near the opening of the barrel 11. As a result, the coil spring 16 connects the barrel 11 and the annular member 15 so that they can move relative to each other. As shown in Figures 4 to 10, the annular member 15 can move in the axial direction of the barrel 11 relative to the barrel 11 as the tip holder 13 moves and the coil spring 16 expands and contracts.

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

3(a) to 3(f), the outer peripheral surface of the annular member 15 is, from the front side, a tip truncated cone outer surface 15g (maximum diameter φ4.2 mm, minimum diameter φ4.8 mm, axial length 0.3 mm), a tip cylindrical surface 15h (φ4.8 mm, axial length 0.5 mm), a contact truncated cone outer surface 15t (maximum diameter φ4.2 mm, minimum diameter φ3.4 mm, axial length 0.4 mm) as a tapered contact surface on the rear end side, and a small outer diameter circular The cylindrical surface 15a (φ3.4 mm, axial length 1.6 mm), the first truncated cone outer surface 15b (axial length 1.2 mm), the medium outer diameter cylindrical surface 15c (φ4.8 mm, axial length 2 mm), the second truncated cone outer surface 15d (axial length 0.3 mm), the first large outer diameter cylindrical surface 15e (φ5.2 mm, axial length 2.4 mm), and the second large outer diameter cylindrical surface 15f (φ6.5 mm, axial length 1 mm) are provided in this order. With reference to FIG. 2, in this embodiment, the rear end of the coil spring 16 is fixed on the step portion defined between the first large outer diameter cylindrical surface 15e and the second large outer diameter cylindrical surface 15f.

As shown in FIG. 3(d), the inner peripheral surface of the annular member 15 is provided with, from the front side, a small inner diameter cylindrical surface 15ia (φ2.4 mm, axial length 3.9 mm) and a large inner diameter cylindrical surface 15ib (φ3.6 mm, axial length 5.9 mm) in that order.

In addition, the annular member 15 of this embodiment has three slits 15s as cutouts. As shown in Figures 3(a) to 3(f), the three slits 15s are arranged at equal intervals (every 120°) around the circumference of the annular member 15. Each of the three slits 15s has a width of 1 mm and extends in the axial direction of the annular member 15 from the front end to the rear end of the first large outer diameter cylindrical surface 15e (maximum axial length 8.8 mm).

As a result, when a load is applied to the abutting truncated cone outer surface 15t (abutting surface), the inner diameter of the annular member 15 flexibly contracts, and when the load is released, the inner diameter of the annular member 15 elastically returns to its original state.

On the other hand, as shown in Figures 2 and 4 to 10, the inner peripheral surface near the opening of the barrel 11 is provided with, in this order from the front side, a small inner diameter cylindrical surface 11ia (φ3.6 mm, axial length 0.6 mm), a truncated conical inner surface 11ib (maximum diameter φ4.95 mm, minimum diameter φ3.6 mm, axial length 1.2 mm), and a large inner diameter cylindrical surface 11ic (φ6.8 mm).

As a result, the abutting truncated cone outer surface 15t (abutting surface) receives a load from the front edge (guide surface) of the small inner diameter cylindrical surface 11ia as the annular member 15 moves toward the rear end side.

In addition, the retractable writing instrument 10 of this embodiment is equipped with a knock spring 12 that automatically retracts 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 the locking mechanism that maintains the tip 14 in a protruding state) (operation load is approximately 50 gf to 300 gf (0.49 N to 2.94 N). For example, the operation load when not in use (Figure 2) is 67 gf, the load at full stroke (Figure 5) is 285 gf, and the operation load when writing (Figure 6) is 225 gf. The spring constant is 0.23 N/mm. As is clear from a functional standpoint, the restoring force (spring constant) of the knock spring 12 is greater than the restoring force (spring constant) of the coil spring 16.

The retractable writing instrument 10 configured as described above operates as follows.

When not in use, the tip 14 (writing body) of the retractable writing instrument 10 is in a retracted state as shown in Figures 1 and 2. At this time, the axial length of the coil spring 16 is 6.0 mm, and it is compressed by 2.0 mm from its natural length, the annular member 15 is slightly reduced in diameter, and the small inner diameter cylindrical surface 15ia of the annular member 15 is approximately φ2.39 mm (<outer diameter of the tip 14).

When the tip is protruded (for example, by sliding the operating part provided on the side of the writing instrument), the tip 14 (writing body) of the retractable writing instrument 10 reaches the state shown in Figure 4.

In the state shown in FIG. 4, the tip holder 13 has been moved forward by the tip 14 protruding operation, but the tip 14 and tip holder 13 have not yet transmitted a moving force to the annular member 15 and coil spring 16, and the axial length of the coil spring 16 is still 6.0 mm, compressed by 2.0 mm from its natural length, the annular member 15 has been slightly reduced in diameter, and the small inner diameter cylindrical surface 15ia of the annular member 15 is approximately φ2.39 mm (<outer diameter of tip 14).

Next, when the tip protruding operation (for example, sliding the operating part provided on the side of the writing instrument) is continued, the tip 14 (writing body) of the retractable writing instrument 10 reaches the state shown in Figure 5.

In the state shown in FIG. 5, the tip holder 13 is moved forward by the tip 14 protruding operation, but the tip of the tip holder 14 moves forward while expanding the annular member 15, which had been slightly reduced in diameter (the small inner diameter cylindrical surface 15ia of the annular member 15 is φ2.5 mm (= the outer diameter of the tip 14)). In addition, with the expansion of the annular member 15, the abutting truncated cone outer surface 15t of the annular member 15 is moved slightly forward to avoid interference with the small inner diameter cylindrical surface 11ia of the shaft tube 11. As a result, the axial length of the coil spring 16 becomes 5.9 mm, that is, it is compressed by 2.05 mm from the natural length. FIG. 6 is a schematic vertical cross-sectional view of the entire retractable writing instrument 10 in the state shown in FIG. 5.

Next, when the tip protruding operation (for example, sliding the operating part provided on the side of the writing instrument) is continued, the tip 14 (writing body) of the retractable writing instrument 10 reaches the state shown in Figure 7.

In the state shown in FIG. 7, the tip holder 13 is moved further forward by the tip 14 protruding operation, but the step portion defined between the tip 14 and the second collar portion 13c presses the step portion defined between the small inner diameter cylindrical surface 15ia and the large inner diameter cylindrical surface 15ib of the annular member 15 forward, and the axial length of the coil spring 16 becomes 5.1 mm, which is compressed by 2.9 mm from its natural length. As a result, the abutting truncated cone outer surface 15t of the annular member 15 is completely separated from the small inner diameter cylindrical surface 11ia of the barrel 11, and the annular member 15 is further enlarged in diameter than in the state shown in FIG. 5. FIG. 8 is a schematic vertical cross-sectional view of the entire retractable writing instrument 10 in the state shown in FIG. 7.

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 holder 13 returns to the rear end, i.e., the forward moving force applied from the tip holder 13 to the annular member 15 is released. As a result, the annular member 15 also returns to the rear end due to the restoring force of the coil spring 16. Here, as the annular member 15 moves to the rear end, the abutting truncated cone outer surface 15t (abutting surface) receives a load from the front edge (guide surface) of the small inner diameter cylindrical surface 11ia of the barrel 11, and the inner diameter of the annular member 15 decreases. This state is shown in FIG. 9. This allows the tip holder 14 to be held without any rattling (play).

Here, the shaft tube 11 and the annular member 15 are connected by the coil spring 16 so that they can move relative to each other, so that it is possible to ensure that the tip 14 is effectively gripped without any rattling (play) even without highly accurate dimensional control over the degree of reduction in the inner diameter of the annular member 15.

In the state shown in FIG. 9, the axial length of the coil spring 16 is 5.9 mm, i.e., it is compressed by 2.1 mm from its natural length (same as the state shown in FIG. 5 in this embodiment). Normally, the position of the tip holder 13 is locked in the protruding state shown in FIG. 9, and the protruding state of the tip 14 is maintained until the tip is retracted.

After that, when the tip is retracted (for example, the operating part on the side of the writing instrument is slid again), 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 Figures 7 and 8, and then, due to the action (restoring force) of the knock spring 12, it returns to the retracted state shown in Figure 2 via the states shown in Figures 4 to 6.

In addition, during the above-mentioned process of tip extension and retraction (particularly when the tip is retracted (Figure 2)), the contact surface of the annular member 15 (the contact truncated cone outer surface 15t) and the guide surface of the barrel 11 (the front edge of the small inner diameter cylindrical surface 11ia) are always in contact with each other. This is also the case when the tip 14 goes from a protruding state to a retracted state.

As described above, according to the retractable writing instrument 10 of this embodiment, as the annular member 15 moves toward the rear end side, the contact surface (contact truncated cone outer surface 15t) of the annular member 15 receives a load from the guide surface (front edge of the small inner diameter cylindrical surface 11ia) 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 rattle (play). Furthermore, since the barrel 11 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 possible to ensure that the tip 14 is effectively held without any rattle (play) even without highly accurate dimensional control of the degree of reduction in the inner diameter of the annular member 15.

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.

In addition, since the contact surface of the annular member 15 (contact truncated cone outer surface 15t) and the guide surface of the shaft tube 11 (the front edge of the small inner diameter cylindrical surface 11ia) are a corresponding truncated cone outer surface and a concave cylindrical surface, the contact surface of the annular member 15 can receive a load in a circumferentially balanced manner, and as a result, the annular member 15 can reduce in diameter in a circumferentially balanced manner.

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

In addition, according to the retractable writing instrument 10 of this embodiment, when the tip is retracted, the contact surface of the annular member 15 (the contact truncated cone outer surface 15t) and the guide surface of the barrel 11 (the front edge of the small inner diameter cylindrical surface 11ia) are always in contact with each other. This prevents the annular member from separating from the barrel inner surface, suppressing rattling caused by vibration.

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 and without rattling (play).

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 operating the tip 14 to retract or retract, or at the rear of the barrel 11. When a conventional configuration is used in a thermochromic writing instrument, there is a risk that the vibration caused by rubbing the writing may cause the tip (or tip holder) to rattle and generate noise, but this risk does not occur with the configuration of this embodiment. Therefore, it is also recommended that the configuration of this embodiment be used in a thermochromic writing instrument.

(Additional information about refills)
The retractable writing instrument 10 of this embodiment is a writing instrument comprising a barrel 11, a refill (writing body) contained within the barrel 11, and a retractable mechanism that allows the tip 14 of the refill to be freely retracted and retracted from the opening of the barrel 11.

An example of a refill will be further explained with reference to Figs. 25 to 27. Referring to Fig. 25, the refill 6 comprises, for example, a pen tip (tip) 61, an ink reservoir 62 into whose front end opening the pen tip 61 is press-fitted, 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 has 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.

The pen tip 61 is, for example, either composed of only a metal ballpoint pen tip that rotatably holds a ball at its front end, or composed 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, composed of a compression coil spring with a rod portion at the front end, and the front end of the rod portion is in contact with the rear surface of the ball. When not writing, the forward bias of the spring keeps the ball in close contact with the inner surface of the inward-facing front edge of the front end of the ballpoint pen tip. This prevents ink from leaking from the front end of the pen tip 61 and ink from evaporating.

(Additional information regarding the rear end of the barrel 11)
The axle tube 11 of this embodiment comprises, for example, a tapered cylindrical front axle 3 (see FIG. 28), a cylindrical intermediate shaft 4 (see FIG. 29) connected to the rear end of the front axle 3, and a cylindrical rear axle 5 (see FIG. 30) connected to the rear end of the intermediate shaft 4.

For example, as shown in FIG. 30, a mounting hole 52 may be provided in the rear end of the rear axle 5 in the front-rear direction, and a friction part 53 made of an elastic material may be press-fitted into the mounting hole 52. This allows the friction part 53 to be fixed to the outer surface of the rear end of the rear axle 5. Also, an inward protrusion 54 may be integrally formed on the inner surface of the rear axle 5.

The elastic material constituting the friction portion 53 is preferably, for example, a synthetic resin (rubber, elastomer) having elasticity, 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 types of rubber elastic materials, and a mixture of a rubber elastic material and a synthetic resin.

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 axle tube 11 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 axle tube 11 or the outer surface of the rear end of the rear axle 5 by press-fitting, engaging, screwing, fitting, gluing, two-color molding, etc., or the entire axle tube 11 or the entire rear axle 5 can be integrally formed from an elastic material.

(Additional information regarding the knock member 8)
31 , a clip 83 extending in the front-rear direction can be fixed to the knock member 8. A ball portion can 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.

The knock member 8 is obtained, for example, by a molded body of synthetic resin (for example, polycarbonate resin). The clip 83 is obtained, for example, by a molded body of 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 from synthetic resin.

As shown in FIG. 31, 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 rotating member 7 (see FIGS. 32 to 35).

To assemble the knock member 8, the base 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. Then, while fitting the inner surface of the rear shaft 5 to the outer surface of the reduced diameter portion of the intermediate shaft 4, the base 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 are radially connected (overlapping in the radial direction). 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 pass over each other), and the first long hole 41 and the second long hole 51 form a slide hole 21 that extends in the front-rear direction, and the knock member 8 protrudes radially outward from the slide hole 21. The knock member 8 is slidable in the front-rear direction along the slide hole 21 (slidable in the front-rear direction).

The rear axle 5, which has a friction part 53 fixed to its rear end, is connected to the rear end of the intermediate axle 4, so that the friction part 53 is always fixed to the rear end of the barrel 11. In addition, the front axle 3 and the intermediate axle 4 are connected detachably by screwing together, so the refill 6 can be replaced at any time.

(Additional information on the haunting mechanism)
The retractable mechanism of this embodiment is a side-slide type retractable mechanism that uses a rotating cam mechanism, and consists 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 11 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 11 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 11 and urges the refill 6 rearward.

The retraction mechanism in this embodiment is a double knock type in which the knock member 8 is pressed forward (slid forward) for both the pen tip extension operation and the pen tip retraction operation.

(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.

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 (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the reaction (coloring reaction) in which the two chemically bind together occurs is encapsulated in a microcapsule is preferably used.

10 Retractable writing implement 11 Barrel 11ia Small inner diameter cylindrical surface 11ib Truncated cone inner surface 11ic Large inner diameter cylindrical surface 11m Front portion 11r Rear portion 12 Knock spring 13 Tip holder 13a Base end portion 13b First collar portion 13c Second collar portion 14 Tip 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 Second large outer diameter cylindrical surface 15g Tip truncated cone outer surface 15h Tip cylindrical surface 15ia Small inner diameter cylindrical surface 15ib Large inner diameter cylindrical surface 15s Slit 15t Abutting truncated cone outer surface 16 Coil spring 3 Front shaft 32 Main body 33 Grip portion 4 Intermediate shaft 41 First long hole 42 Step portion 43 Cam portion 43a Cam teeth 43b Cam groove 44 Outward projection 5 Rear shaft 51 Second long hole 52 Mounting hole 53 Friction portion 54 Inward projection 6 Refill (cursive)
[0033] 61 pen tip 62 ink reservoir 63 tail plug 63a air hole 63b protrusion 63c gap 63d small diameter portion 63e large diameter portion 63f flange 63g engagement surface 63p outward projection 63t auxiliary tapered portion 7 retractable rotating member 71 protrusion 72 projection 72a engagement surface 73 abutment portion 74 annular auxiliary projection 74t auxiliary abutment surface 78 outward projection 8 knock member 81 base 82 shaft portion 82a cam teeth 83 clip 88 inward projection 110 retractable writing instrument 111 shaft tube 111a rear portion 111b inner tube portion 111c front portion 111d ferrule portion 111t guide surface 112 second coil spring 113 tip holder 113a base end portion 113b first collar portion 113c Second collar portion 113d Tip portion 113f Spring fixing auxiliary portion 114 Tip 115 Annular member 115a Large outer diameter cylindrical portion 115b Small outer diameter cylindrical portion 115s Slit 115t Contact surface 116 Coil spring 120 Retractable writing instrument 123 Tip holder 123a Base end portion 123b First collar portion 123c Second collar portion 123d Tip portion 124 Tip 125 Annular member 125s Slit 125t Contact surface 126 Resin spring portion 126e Resin spring portion 130 Retractable writing instrument 132 Collar member 133 Tip holder 133a Base end portion 133b First collar portion 133c Second collar portion 133d Tip portion 133m Intermediate collar portion 134 Tip 140 Retractable writing instrument 142 Collar member 143 Tip holder 143a Base end 143b First collar portion 143c Second collar portion 143d Tip portion 143m Intermediate collar portion 144 Tip

Claims (18)

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 that connects the barrel and the annular member so as to be movable relative to each other;
a knock spring that biases the tip holder toward the rear side in the axial direction of the barrel;
Equipped with
a contact surface that contacts a part of the inner surface of the opening of the barrel is formed on at least a part of the outer periphery of the annular member;
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 an inner surface of the opening of the barrel, the guide surface being in contact with the abutment surface as the annular member moves toward the rear end side;
the annular member moves toward the front end together with the chip holder while elastically deforming the elastic member as the chip holder moves toward the front end against the biasing force of the knock spring, and as the chip holder subsequently moves toward the rear end, the annular member moves toward the rear end by a restoring force of the elastic member that is separate from the biasing force of the knock spring,
The abutment surface is adapted to receive the load from the guide surface as the annular member moves toward the rear end side.
A retractable writing instrument characterized by: The retractable writing instrument as described in claim 1, characterized in that the annular member moves toward the front end together with the tip holder while elastically deforming the elastic member by pressing a step portion of the annular member forward as the tip holder moves toward the front end against the biasing force of the knock spring . A plurality of the notches are disposed at equal intervals in the circumferential direction of the annular member,
3. The retractable writing instrument according to claim 1, wherein each of the plurality of cutouts is a slit extending in the axial direction of the annular member. The annular member has a flange at a front end,
The flange portion is located outside the barrel,
The contact surface is tapered toward the rear end of the flange.
4. The retractable writing instrument according to claim 1, 5. The retractable writing instrument according to claim 4, wherein the contact surface has a truncated cone surface. 6. The retractable writing instrument according to claim 1, wherein the elastic member is a coil spring. 7. The retractable writing implement according to claim 1, wherein the contact surface and the guide surface are constantly in contact with each other when the tip is retracted. 8. The retractable writing instrument according to claim 1, wherein the annular member protrudes forward from the opening of the barrel. 9. The retractable writing instrument according to claim 1, wherein a soft member is provided at an operating portion for operating the tip to extend or retract, or at a rear portion of the barrel. A barrel assembly for a retractable writing instrument, the barrel assembly being capable of axially movably housing a tip holder having a tip fixed to a front end thereof, the barrel having an opening at the front end thereof, and capable of causing the tip to protrude and retract from the opening 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 that connects the barrel and the annular member so as to be movable relative to each other;
a knock spring that biases the tip holder toward the rear side in the axial direction of the barrel;
Equipped with
a contact surface that contacts a part of the inner surface of the opening of the barrel is formed on at least a part of the outer periphery of the annular member;
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 an inner surface of the opening of the barrel, the guide surface being in contact with the abutment surface as the annular member moves toward the rear end side;
the annular member moves toward the front end together with the chip holder while elastically deforming the elastic member as the chip holder moves toward the front end against the biasing force of the knock spring, and as the chip holder subsequently moves toward the rear end, the annular member moves toward the rear end by a restoring force of the elastic member that is separate from the biasing force of the knock spring,
As the annular member moves toward the rear end side, the abutment surface
The load is received from the guide surface.
A barrel assembly for a retractable writing instrument, comprising: The annular member is configured to move toward the front end together with the tip holder while elastically deforming the elastic member by pressing a step portion of the annular member forward as the tip holder moves toward the front end against the biasing force of the knock spring. The barrel assembly for a retractable writing instrument as described in claim 10. A plurality of the notches are disposed at equal intervals in the circumferential direction of the annular member,
12. The barrel assembly for a retractable writing instrument according to claim 10 or 11, wherein each of the plurality of notches is a slit extending in the axial direction of the annular member. The annular member has a flange at a front end,
The flange portion is located outside the barrel,
The contact surface is tapered toward the rear end of the flange.
13. A barrel assembly for a retractable writing instrument according to any one of claims 10 to 12. 14. The barrel assembly for a retractable writing instrument according to claim 13, wherein the abutment surface has a frustoconical surface. 15. The barrel assembly for a retractable writing instrument according to claim 10, wherein the elastic member is a coil spring. 16. The barrel assembly for a retractable writing instrument according to claim 10, wherein the contact surface and the guide surface are constantly in contact with each other when the tip is retracted. 17. The barrel assembly for a retractable writing instrument according to claim 10, wherein the annular member protrudes forward from the opening of the barrel. 18. The barrel assembly for a retractable writing instrument according to claim 10, wherein a soft member is provided at an operating portion for operating the tip to extend or retract, or at a rear portion of the barrel .

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