Retractable writing instrument

Abstract

To provide a retractable writing instrument that allows a tail plug to be stably installed in a rear end opening of a barrel in order to solve the problem of the retractable writing instrument disclosed in Patent Document 1 that an edge part forming a window hole may open in a circumferential direction due to molding, which can cause a positional relation between a locking portion and a locked portion to become misaligned, making mounting work of the tail plug unstable.SOLUTION: Provided is a retractable writing instrument in which a clamping protrusion consisting of at least two protrusions is provided in an insertion portion in front of a tail plug, a notch is provided where an edge part forming a rear end opening of a barrel and an edge part forming a window hole are connected, and a clamped protrusion is provided on an inner wall surface of the barrel, circumferentially spanning the edge part forming the window hole connected to the notch, and is clamped circumferentially by the clamping protrusion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a so-called retractable writing instrument in which a writing instrument body having a writing part at its front end is arranged inside a barrel so as to be movable back and forth, and the writing part can be protruded from and retracted into the front end opening of the barrel, and the retractable writing instrument has a structure in which a tail plug is attached to the rear end opening of the barrel. Hereinafter, the direction in which the writing part protrudes will be referred to as the front, and the direction in which the writing part retracts will be referred to as the rear. Furthermore, the state in which the writing part protrudes from the front end opening of the barrel and is ready for writing will be referred to as the protruding state, and the state in which the writing part retracts inside the barrel will be referred to as the retracted state. [Background technology]

[0002] Conventionally, retractable writing instruments have been known that have an opening at the rear end of the barrel so that components such as a writing lead can be placed inside the barrel. The opening is generally closed with a tail plug to prevent the components placed inside from falling out or damaging the appearance during transportation or use of the retractable writing instrument.

[0003] For example, Patent Document 1 (JP 2019-116038 A) discloses a retractable writing instrument in which the rear end opening of the barrel has a locking portion that protrudes radially outward and the tail plug has a lockable portion that protrudes radially inward, and when the tail plug is attached, the locking portion overcomes the lockable portion, allowing the tail plug to be attached to the rear end opening of the barrel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-116038 Summary of the Invention [Problem to be solved by the invention]

[0005] The retractable writing instrument disclosed in Patent Document 1 has a window hole formed from the edge forming the rear end opening of the barrel to the barrel side wall, extending forward in the longitudinal direction of the barrel. The edge forming the window hole can open in the circumferential direction due to shrinkage after molding, etc. This can cause the positional relationship between the locking part and the locked part to become misaligned, making the installation of the tail plug unstable.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a writing instrument in which a tail plug can be stably attached to an opening at the rear end of a barrel. [Means for solving the problem]

[0007] The first gist of the present invention is a retractable writing instrument in which a writing instrument body with a writing part at its front end is arranged inside a transparent barrel so that it can move back and forth, an actuator is arranged at the rear end of the writing instrument body, a window hole is formed in the side wall of the barrel that penetrates from the inside to the outside of the barrel and extends in the front-to-back direction, a part of the actuator is exposed to the outside of the barrel through the window hole, and the writing part can be made to protrude and retract from the front-end opening of the barrel by moving this part back and forth, a tail plug is attached to the rear-end opening of the barrel, and an insertion part that is inserted into the rear-end opening of the barrel is provided in front of the tail plug, a clamping protrusion consisting of at least two protrusions is provided on the insertion part, and a notch is formed by connecting the edge that forms the rear-end opening of the barrel and the edge that forms the window hole, and a clamped protrusion that is clamped circumferentially by the clamping protrusion is provided on the inner wall surface of the barrel, spanning the edge that forms the window hole that is connected to the notch in the circumferential direction. A second aspect of the present invention is a retractable writing implement in which the front end of the clamping protrusion is the front end of the insertion portion. [Effects of the Invention]

[0008] The writing instrument of the present invention can circumferentially sandwich a sandwiched protrusion provided so as to straddle in the circumferential direction an edge portion forming a window hole connected to a notch portion, so that it is possible to prevent the edge portion forming the window hole from opening in the circumferential direction, and the tail plug can be stably attached to the rear end opening of the shaft cylinder. Further, in the second gist, during the attachment operation, the sandwiched protrusion of the tail plug can be brought into contact with the shaft cylinder first, and it is possible to prevent the edge portion forming the window hole connected to the notch portion from opening in the circumferential direction almost simultaneously with the start of the attachment operation, and the tail plug can be stably attached to the rear end opening of the shaft cylinder.

Brief Description of Drawings

[0009] [Figure 1] External view of ballpoint pen 1 [Figure 2] Cross-sectional view taken along line A-A' of FIG. 1, arrow view [Figure 3] External view of writing instrument body 3 [Figure 4] (a) External view of rear shaft 2b, (b) Cross-sectional view taken along line B-B' of FIG. 4(a), arrow view<00,00054> [Figure 5] External perspective view of rear shaft 2b <0000,057>External perspective view of tail plug 7 [Figure 7] Cross-sectional view of the state where tail plug 7 is attached to rear end opening 2bb [Figure 8] External perspective view of buffer material 4 [Figure 9] External perspective view of partitioning member 5 [Figure 10] Longitudinal sectional view of partitioning member 5 [Figure 11] Front enlarged view of longitudinal section of rear shaft 2b [Figure 12] Enlarged view of part C in FIG. 11

Modes for Carrying Out the Invention

[0010] The present invention can be embodied as a retractable writing instrument such as a ballpoint pen, mechanical pencil, brush pen, felt-tip pen, or marking pen, in which a writing part such as a ballpoint pen tip can be protruded and retracted from an opening at the front end of the barrel. Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] Figure 1 is an external view of a ballpoint pen 1, which is a retractable writing implement according to one embodiment of the present invention, and Figure 2 is a cross-sectional view taken along line A-A' in Figure 1. Ballpoint pen 1 has three writing implement bodies 3, a buffer member 4, a partition member 5, and a coil spring 6 as a resilient member arranged inside a hollow cylindrical barrel 2.

[0012] FIG. 3 is an external view of the writing instrument body 3. The ballpoint pen 1 is a retractable multi-core writing instrument with three writing instrument bodies 3 arranged inside a transparent barrel 2. The writing instrument body 3 is configured with a ballpoint pen refill 3a, the front end of which is provided with a ballpoint pen tip 3aa as a writing part, and an actuator 3ba or a clip actuator 3bb arranged at the rear end. Of the three writing instrument bodies 3, two have actuator 3ba arranged in the ballpoint pen refill 3a (FIG. 3(a)), and the remaining one has clip actuator 3bb arranged in the ballpoint pen refill 3a (FIG. 3(b)). A clip 3bc is attached to clip actuator 3bb.

[0013] The barrel 2 is composed of a front barrel 2a and a rear barrel 2b. The rear of the front barrel 2a is inserted through the front open end of the rear barrel 2b. A threaded portion is provided on the rear outer wall surface of the front barrel 2a and the front inner wall surface of the rear barrel 2b, respectively, allowing the front barrel 2a and the rear barrel 2b to be joined by screwing together. The writing instrument body 3 can be easily positioned or replaced by releasing the screw threads. The barrel 2 may be transparent or translucent to the extent that the interior of the front barrel 2a and / or rear barrel 2b can be seen from the outside.

[0014] The front shaft 2a is a two-color molded product, with the primary side located on the radially inner side of the front shaft 2a being made of polypropylene resin and the secondary side located on the radially outer side of the front shaft 2a being made of thermoplastic elastomer. The outer wall surface of the front shaft 2a is given a matte finish, which functions as a grip that makes it easier for the user to hold.

[0015] Front barrel 2a can be formed into any desired shape by any known method other than two-color molding as in this embodiment. The grip can also be formed as a separate member that covers the outer wall surface of front barrel 2a.

[0016] Other materials that can be used for the front axle 2a include polycarbonate resin, acrylic resin, polyethylene resin, polyamide resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polyethylene naphthalate resin, vinyl chloride resin, ethylene-vinyl alcohol copolymer, polyacrylonitrile resin, fluororesin, polyacetal resin, polyethylene terephthalate resin, polystyrene resin, ABS resin, silicone resin, elastomer, and composite materials containing these resins, taking into consideration moldability and durability. The molding method is not limited to two-color molding as in this embodiment, and various known methods can be selected as appropriate.

[0017] FIG. 4(a) is an external view of rear barrel 2b, FIG. 4(b) is a cross-sectional view taken along line B-B' in FIG. 4(a), and FIG. 5 is an external perspective view of rear barrel 2b. A window hole 2ba extending in the front-to-rear direction and penetrating from the inside to the outside of rear barrel 2b is provided in the rear sidewall of rear barrel 2b. The number of window holes 2ba is the same as the number of writing instrument body 3, and in this embodiment, three window holes 2ba are provided. A portion of actuator 3ba and clip actuator 3bb are exposed to the outside of barrel 2 through window holes 2ba. A clip 3bc can be attached to the portion of clip actuator 3bb exposed to the outside of barrel 2. When the portion of actuator 3ba exposed to the outside of barrel 2 and clip 3bc are manipulated from rear to front along window hole 2ba, writing instrument body 3 advances within barrel 2 in tandem.

[0018] The writing instrument body 3 is biased rearward by a coil spring 6. The front end of the coil spring 6 abuts against the rear end surface of the partition member 5, which is arranged inside the barrel 2 so as not to be able to move back and forth. The rear end of the coil spring 6 abuts against a step provided in front of the actuator 3ba and the clip actuator 3bb. When the coil spring 6 is compressed from its natural state, it is sandwiched between the partition member 5, the actuator 3ba, and the clip actuator 3bb, and constantly biases the writing instrument body 3 rearward.

[0019] When the actuator 3ba (or clip 3bc) is operated to move the writing instrument body 3 forward, the shoulder 3baa (or shoulder 3bba) of the actuator 3ba (or clip actuator 3bb) engages with the front end of the clamped protrusion 2bd provided inside the rear barrel 2b and extending in the front-to-rear direction, causing the ballpoint pen tip 3aa to protrude from the front end opening of the front barrel 2a. The shoulders 3baa and 3bba protrude in the chord direction inside the cylindrical rear barrel 2b, and engage with the front end of the clamped protrusion 2bd that is adjacent to one writing instrument body 3 in the circumferential direction.

[0020] When one of the writing instrument bodies 3 is in the protruding state, if the other actuator 3ba (or clip 3bc) in the retracted state is operated and advanced, the actuator 3ba (or clip 3bc) of the protruding writing instrument body 3 will come into contact with the advanced actuator 3ba (or clip 3bc). Then, the actuator 3ba (or clip 3bc) of the protruding writing instrument body 3 will be disengaged from the clamped projection 3bd, and the ballpoint pen tip 3aa of the protruding writing instrument body 3 will retract into the barrel 2. By performing the above series of operations, the user can select any writing instrument body 3 and use the ballpoint pen 1 for writing.

[0021] Figure 6 is an external perspective view of the tail plug 7. A rear end opening 2bb is provided at the rear end of the rear barrel 2b as the rear end opening of the barrel 2. Each writing instrument body 3 can be placed inside the barrel 2 through the rear end opening 2bb. The rear end opening 2bb is closed when the tail plug 7 is attached.

[0022] Rear barrel 2b has cutout 2bc formed by joining the edge forming rear end opening 2bb and the edge forming window hole 2ba. Cutout 2bc allows writing instrument body 3 with clip 3bc attached to clip actuator 3bb to be smoothly inserted through rear end opening 2bb.

[0023] The tail plug 7 is a cylindrical member with a bottom. An insertion portion 7a is provided at the front of the tail plug 7. The insertion portion 7a is the portion of the tail plug 7 that is inserted through the rear end opening 2bb of the rear barrel 2b. Window hole protrusions 7ab are provided in two locations on the outer wall surface of the insertion portion 7a. When the insertion portion 7a is inserted into the rear end opening 2bb, each window hole protrusion 7ab ultimately engages with the rear end surface of the edge that constitutes each window hole 2ba, preventing the tail plug 7a from falling off rearward and ensuring its attachment.

[0024] The insertion portion 7a is provided with two clamping protrusions 7aa, which are protrusions of the insertion portion 7a that extend forward in the front-rear direction.

[0025] Figure 7 is a cross-sectional view of the tail plug 7 attached to the rear end opening 2bb. The view is from the front, with the tail plug 7 positioned at the back of the drawing. On the inner wall surface of the rear axle 2b, a clamped protrusion is provided that straddles the edge that forms the window hole 2ba connected to the cutout portion 2bc in the circumferential direction and is clamped in the circumferential direction by the clamping protrusions 7aa. The clamped protrusion 2bd is a protrusion that protrudes from the inner wall surface of the rear axle 2b and extends in the front-to-rear direction. The radially inner tip portions of the clamped protrusions 2bd are each forked.

[0026] When the insertion portion 7a is inserted through the rear-end opening 2bb, the clamping protrusion 7aa clamps the clamped protrusion 2bd in the circumferential direction. Of the two prongs at the radially inner tip portion of the clamped protrusion 2bd, one prong closer to the notch 2bc and the edge forming the window hole 2ba connected to the notch 2bc is clamped by the circumferentially inner side wall of the clamping protrusion 7aa. The edge forming the notch 2bc tends to separate circumferentially and open easily after molding of the rear body 2b. Therefore, the two clamped protrusions 2bd are provided circumferentially across the edge of the window hole 2ba connected to the notch 2bc. This prevents the edge forming the window hole 2ba from opening circumferentially when the tail plug 7 is attached, which is preferable because it allows the tail plug 7 to be stably attached to the rear-end opening 2bb. When the edge portion forming the window hole 2ba tries to open in the circumferential direction, the force in the circumferential direction with which the sandwiching protrusion 7aa sandwiches the sandwiched protrusion 2bd becomes stronger, which is preferable.

[0027] When using a clip actuator 3bb that has a shoulder 3ba and is wide in the chord direction of the cylindrical rear barrel 2b as in this embodiment, the space within the rear barrel 2b to accommodate the writing instrument body 3 with the clip actuator 3bb arranged therein and to allow it to move back and forth requires width in both the circumferential and chord directions, so it is preferable to use the clamping protrusion 7aa to prevent the edge forming the window hole 2ba from opening in the circumferential direction.

[0028] Furthermore, the front end of the clamping protrusion 7aa is located at the front most position of the insertion portion 7a, and is the front end of the insertion portion 7a. As a result, when attaching the tail plug 7 to the rear end opening 2bb, the clamping protrusion 7aa of the insertion portion 7a can be brought into contact with the barrel 2 first, and the clamped protrusion 2bd can be clamped almost simultaneously with the start of the attachment work. Therefore, the attachment strength is generated immediately after the start of the attachment work, which is preferable because the tail plug 7 can be stably attached to the rear end opening 2bb.

[0029] FIG. 8 is an external perspective view of the cushioning member 4. The cushioning member 4 is a soft member made of butyl rubber. The cushioning member 4 is composed of an insertion portion 4a extending rearward and a cushioning portion 4b located forward. The insertion portion 4a extends rearward from the rear end face of the cushioning portion 4b. A space is provided radially inside the insertion portion 7a of the tail plug 7, into which the insertion portion 4a is inserted when attaching the cushioning member 4. A groove 4aa is provided in the outer wall of the insertion portion 4a, recessed radially inward in the front-to-rear direction. An internal rib 7ac extending in the front-to-rear direction is provided on the inner wall surface of the insertion portion 7a of the tail plug 7, which forms the space into which the insertion portion 4a is inserted. The groove 4aa is aligned with the internal rib 7ac, which allows for circumferential positioning of the cushioning member 4, improving assembly and making this preferable.

[0030] When each writing instrument body 3 is changed from the extended state to the retracted state, the writing instrument body 3 moves rearward inside the barrel 2, causing the rear end of the actuator 3ba or the clip actuator 3bb to come into contact with the buffer part 4b, which is the front end of the buffer member 4. Because the buffer member 4 is soft, the sound of the collision with the actuator 3ba or the clip actuator 3bb is reduced, which is preferable.

[0031] Fig. 9 is an external perspective view of the partition member 5, Fig. 10 is a vertical cross-sectional view of the partition member 5, Fig. 11 is an enlarged front view of the vertical cross-section of the rear body 2b, and Fig. 12 is an enlarged view of part C in Fig. 11. The partition member 5 is a member that is attached inside the barrel 2. In this embodiment, it is attached inside the rear body 2b.

[0032] The partitioning member 5 is composed of a partitioning protrusion 5a extending rearward and a tubular portion 5b extending forward. The partitioning protrusion 5a extends rearward from the rear end face of the tubular portion 5b and is a protrusion with a trifurcated radial tip. The tubular portion 5b is provided with through holes 5ba that penetrate in the front-rear direction and through which the ballpoint pen refills 3a are inserted. In this embodiment, three through holes 5ba are provided, the number of which corresponds to the number of writing instrument bodies 3. The front ends of each coil spring 6 abut against the rear end face of the tubular portion 5b near the opening of each through hole 5ba. When each ballpoint pen refill 3a moves back and forth inside the barrel 2, the inner wall of the through hole 5ba and the side wall of the partitioning protrusion 5a prevent them from interfering with each other in the radial direction. This makes the forward and backward movement of each ballpoint pen refill 3a smoother, which is preferable.

[0033] The outer wall of the cylindrical portion 5b is provided with three grooves 5bb that are recessed radially inward in the front-to-rear direction and are spaced equally apart in the circumferential direction. When the partition member 5 is attached to the inside of the rear axle 2b, the grooves 5bb are attached along the ribs 2be that are on the inner wall surface of the rear axle 2b and extend in the front-to-rear direction, which makes it possible to position the partition member 5 in the circumferential direction and improves assembly, which is preferable.

[0034] A circumferential projection 5bc projecting radially like a flange is provided on the outer wall surface of the cylindrical portion 5b. In this embodiment, the circumferential projection 5bc is provided at a position where the rear end surface of the cylindrical portion 5b forms the rear end surface of the side wall of the circumferential projection 5bc.

[0035] The inner wall surface of the rear axle 2b is provided with a circumferential groove 2bf into which the circumferential protrusion 5bc can be inserted when the partition member 5 is attached. The circumferential groove 2bf is formed by a side wall surface 2bfa, a bottom surface 2bfb along the front-to-rear direction, and a connecting portion 2bfc between them. When the circumferential protrusion 5be is inserted into the circumferential groove 2bf, the partition member 5 is attached so as to be unable to move forward or backward by the side wall surface 2bfa of the inner wall surface of the rear axle 2b that forms the circumferential groove 2bf and abuts the circumferential protrusion 5bc in the front-to-rear direction.

[0036] The connecting portions 2bfc between the side wall surfaces 2bfa and the bottom surface 2bfb are curved surfaces. When a straight line is drawn between both radial ends of the side wall surfaces 2bfa and the center of the bottom surface 2bfb in the front-to-rear direction, the straight line forms a curved surface that protrudes radially outward.

[0037] Here, rear barrel 2b is a molded product made of polycarbonate resin. Each component of a writing instrument is typically a resin molded product made by molding resin in a mold. For example, in the case of a cylindrical component like rear barrel 2b, a cylindrical pin with a smaller diameter than the cavity is inserted and / or placed in the cavity, which has a cylindrical cavity. Resin is poured between the cavity and the pin, and once the resin hardens and the pin is removed, the resin becomes a molded product of the desired shape, forming a cylindrical component.

[0038] To form the circumferential groove portion 2bf, a circumferential protrusion protruding from the outer wall surface of the pin is required, but when the pin is pulled out, this protrusion becomes a so-called undercut and may come into contact with the inner wall surface of the front end opening side where the threaded portion of the rear axle 2b is provided, and may be scraped off.

[0039] In this embodiment, both the forward and rearward connecting portions 2bfc, which are in the direction in which the pin is pulled out, are curved. In other words, the outer wall surface of the protruding portion that forms the circumferential groove portion 2bf on the outer wall surface of the pin is also curved with a corresponding shape. This allows the protruding portion to smoothly contact the inner wall surface of the rear axle 2b when the pin is pulled out, preventing the inner wall surface of the rear axle 2b from being scraped. This, in turn, makes it easier to mold the rear axle 2b within the desired dimensional range, which is preferable because it allows the partition member 5 to be attached to the rear axle 2b with the desired strength.

[0040] If the connecting portion 2bfc has a curved surface at least in one location, the abutment between the pin and the inner wall surface of the rear axle 2b can be made that much smoother. In this embodiment, the pin is configured to be withdrawn from the front-end opening of the rear axle 2b, but the connecting portion 2bfc farther from the opening (the rear-end opening side of the rear axle 2b) also has a curved surface. When the pin is withdrawn, the outer wall surface of the protruding portion that forms the connecting portion 2bfc closer to the front-end opening abuts against the inner wall surface of the rear axle 2b as it is withdrawn, causing the inner wall surface of the rear axle 2b to expand radially outward and then return to its original dimensions. At this time, if the outer wall surface of the protruding portion that forms the connecting portion 2bfc farther from the front-end opening is curved, the rear axle 2b does not abut against a corner when it returns radially inward, which is preferable because scraping of the inner wall surface of the rear axle 2b can be further suppressed.

[0041] Other materials that can be used for the rear axle 2b include polypropylene resin, acrylic resin, polyethylene resin, polyamide resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polyethylene naphthalate resin, vinyl chloride resin, ethylene-vinyl alcohol copolymer, polyacrylonitrile resin, fluororesin, polyacetal resin, polyethylene terephthalate resin, polystyrene resin, ABS resin, silicone resin, elastomer, or composites containing these resins, which can be selected appropriately taking into consideration moldability and durability. [Explanation of symbols]

[0042] 1 ballpoint pen 2 shaft cylinder 2a front axle 2b rear axle 2ba window hole 2bb rear end opening 2bc Notch 2bd Pinched projection 2be rib 2bf Circumferential groove 2bfa side wall 2bfb bottom 2bfc connection part 3 Writing instrument body 3a ballpoint pen refill 3aa ballpoint pen tip 3ba actuator 3baa Shoulder 3bb Clip Actuator 3bba Shoulder 3bc clip 4. Cushioning material 4a Insertion part 4aa Groove 4b Buffer 5 Compartment members 5a Compartment protrusion 5b Cylinder part 5ba through hole 5bb groove 5bc circumferential process 6 coil springs 7 tail plug 7a Insertion part 7aa clamping protrusion 7ab fenestra protrusion 7ac internal rib

Claims

1. a retractable writing instrument in which a writing instrument body with a writing part at its front end is arranged inside a transparent barrel so as to be movable back and forth, an actuator is arranged at the rear end of the writing instrument body, a window hole is formed in the side wall of the barrel that penetrates from the inside to the outside of the barrel and extends in the front-to-back direction, a part of the actuator is exposed to the outside of the barrel through the window hole, and the writing part can be made to appear and disappear from the front-end opening of the barrel by moving this part back and forth, a tail plug is attached to the rear-end opening of the barrel, an insertion part is provided in front of the tail plug to be inserted into the rear-end opening of the barrel, a clamping protrusion consisting of at least two protrusions is provided on the insertion part, and a notch is formed by connecting the edge that forms the rear-end opening of the barrel and the edge that forms the window hole, and a clamped protrusion is provided on the inner wall surface of the barrel that circumferentially straddles the edge that forms the window hole that is connected to the notch and is clamped circumferentially by the clamping protrusion

2. 2. The retractable writing implement according to claim 1, wherein the front end of the clamping protrusion is the front end of the insertion portion.

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