Ink storage container and writing utensil including ink storage container

Abstract

To provide an ink storage container with a simple structure that enables easy replacement, and a writing utensil including the ink storage container.SOLUTION: An ink storage container 10 comprises: a rear shaft 9 having an opening end 13 opened at one end and a closing end 14 closed at the other end; and a plug 20 provided to the rear shaft 9 so as to close the opening end 13, the plug having a cylinder part 21 configured to fit with an inner face of the opening end 13 of the rear shaft 9, and a bottom wall 22 provided with a slit valve including a slit 26 configured to communicate between the inside and the outside of the rear shaft 9 by elastic deformation.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an ink storage container and a writing instrument including the ink storage container.

Background Art

[0002] Writing instruments having an ink storage container filled with liquid ink are known (for example, Patent Documents 1 and 2). The ink storage containers of the writing instruments described in Patent Documents 1 and 2 are configured as cartridges so that they can be replaced when the internal ink is consumed by use or the like. In order to prevent the internal ink from leaking, the opening end of the ink storage container before replacement is sealed by a disk-shaped plug in Patent Document 1 and by a spherical plug in Patent Document 2.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The ink storage containers described in Patent Documents 1 and 2 are difficult to replace easily because it is necessary to remove the plug or strongly push in the plug for attachment to the writing instrument. Further, once the seal by the plug of the ink storage container described in Patent Document 1 is opened, it is virtually impossible or difficult to seal it again. The ink storage container described in Patent Document 2 has a complicated configuration because it requires a coil spring that supports the plug and a holding member that locks the plug together with the spherical plug.

[0005] An object of the present invention is to provide an ink storage container having a simple configuration and capable of being easily replaced, and a writing instrument equipped with the ink storage container.

Means for Solving the Problems

[0006] According to one aspect of the present invention, there is provided an ink storage container including: a container body having an open end portion at one end and a closed end portion at the other end; a cylindrical portion provided with respect to the container body so as to close the open end portion and configured to fit with an inner surface of the open end portion of the container body; and a bottom wall provided with a slit valve having a slit configured to communicate the inside and outside of the container body by elastic deformation.

[0007] A protruding first fitting portion is formed on an outer surface of the cylindrical portion of the plug body, a recess fitting with the first fitting portion and a large-diameter portion are formed on the inner surface of the container body in front of the recess, and when the plug body is fitted to the container body, the first fitting portion elastically deforms to overcome the large-diameter portion and the fitting is configured.

[0008] According to one aspect of the present invention, there is provided a writing instrument including the above ink storage container and a shaft cylinder having a cylindrical protrusion configured to expand the slit.

[0009] The shaft cylinder has a front shaft and a rear shaft, the front shaft has the cylindrical protrusion, and the ink storage container may be the rear shaft or a cartridge disposed in the rear shaft. The front shaft and the rear shaft are configured to be connected by screwing, and at the time of assembly, with the screwing of the front shaft and the rear shaft, the cylindrical protrusion gradually expands the slit of the slit valve and is configured to penetrate the slit.

Effects of the Invention

[0010] According to an aspect of the present invention, there is provided a common effect of providing an ink storage container having a simple configuration and capable of being easily replaced, and a writing instrument including the ink storage container.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

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Figure 8

Figure 9

Figure 10

Figure 11

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Figure 16

BEST MODE FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Throughout the drawings, common reference numerals are assigned to corresponding components.

[0013] FIG. 1 is a longitudinal sectional view of a writing instrument 1 according to a first embodiment of the present invention. The writing instrument 1 is a capped water-based ballpoint pen.

[0014] The writing instrument 1 has a writing instrument body 2 and a cap 3 that can be attached to both ends of the writing instrument body 2. The cap 3 has a cylindrical cap body 4, a crown 5 attached to the tip of the cap body 4, and a clip 6 attached to the side surface of the cap body 4. A writing core 7 protrudes from the tip of the writing instrument body 2. In this specification, in the axial direction of the writing instrument 1, the side of the writing core 7 is defined as the "front" side, and the side opposite to the writing core 7 is defined as the "rear" side. Also, in the description of each member, based on the state arranged in the writing instrument 1, the "front" side and the "rear" side are defined in the same manner as the writing instrument 1.

[0015] The writing instrument body 2 has a shaft cylinder 11 including a cylindrical front shaft 8 and a cylindrical rear shaft 9 that is screwed onto the inner surface of the rear end portion of the front shaft 8, and a mouthpiece member 12 that fits into the front end portion of the front shaft 8. The rear shaft 9 has an open end portion 13 opened at one end and a closed end portion 14 closed at the other end. A plug body 20 is fitted into the open end portion 13 of the rear shaft 9. Ink is stored inside the rear shaft 9. Therefore, the plug body 20 and the rear shaft 9 into which the plug body 20 is fitted constitute an ink storage container 10 as a whole, and the rear shaft 9 constitutes the container body of the ink storage container 10.

[0016] Inside the front shaft 8, a partition wall 15 is provided that divides the inside of the front shaft 8 in the front-rear direction. In the central part of the partition wall 15, a cylindrical protrusion 16 protruding rearward is formed. By the cylindrical protrusion 16, a communication hole 17 that communicates the front and rear of the partition wall 15 is defined. Inside the front shaft 8 in front of the partition wall 15, a cylindrical collector 18 with a plurality of fins formed on its outer periphery is arranged. The collector 18 is configured to send out the ink from inside the rear shaft 9 through the communication hole 17 by replacing the ink inside the rear shaft 9, which is the container body, with the air inhaled from the outside. A relay core member 19 is arranged so as to penetrate the center of the collector 18.

[0017] The rear end portion of the relay core member 19 is arranged in the communication hole 17 of the cylindrical protrusion 16 and can be impregnated with the ink inside the rear shaft 9. The front end portion of the relay core member 19 is inserted into the rear end portion of the writing core 7. The relay core member 19 is configured to allow the ink to penetrate inside by capillary force. Thereby, the ink inside the rear shaft 9 is supplied to the writing core 7 via the relay core member 19, and writing can be performed on the paper surface or the like.

[0018] FIG. 2 is a perspective view of the plug body 20 of the writing instrument in FIG. 1, FIG. 3 is a front view of the plug body 20 in FIG. 1, FIG. 4 is a cross-sectional view of the plug body 20 taken along line A-A in FIG. 3, and FIG. 5 is a longitudinal sectional view showing the open state of the slit 26 of the plug body 20 in FIG. 1. In FIG. 4, the upper side is the front side and the lower side is the rear side.

[0019] The plug body 20 is a substantially cylindrical member. The plug body 20 includes a cylindrical portion 21 configured to fit with the inner surface of the opening end portion 13 of the rear shaft 9, a bottom wall 22 provided at one end of the cylindrical portion 21, that is, the rear end, and a flange portion 23 formed on the outer surface of the other open end of the cylindrical portion 21, that is, the front end. On the outer surface of the cylindrical portion 21, a first fitting portion 24 formed in an annular protrusion shape is formed. On the outer surface of the cylindrical portion 21 slightly separated rearward from the first fitting portion 24, a large-diameter cylindrical portion 25 having a larger diameter than the cylindrical portion 21 is formed. The first fitting portion 24 has a tapered portion 24a that tapers rearward and an annular surface 24b facing forward. The outer diameter of the first fitting portion 24 is slightly larger than the outer diameter of the large-diameter cylindrical portion 25. In the bottom wall 22, a linear slit 26 passing through the center of the circular bottom wall 22 is formed.

[0020] The plug body 20 is formed of a material having rubber elasticity (viscoelasticity). The plug body 20 is formed of, for example, nitrile rubber, ethylene propylene diene rubber, or the like. In a state where no force is applied to the bottom wall 22, the opposing inner surfaces of the slit 26 are in close contact, and the slit 26 is in a closed state. On the other hand, when a force is applied to the bottom wall 22, the slit 26, in other words, the bottom wall 22 defining the slit 26, elastically deforms to form an opening, and as shown in FIG. 5, the slit 26 is in an open state. Therefore, the plug body 20 or the bottom wall 22 constitutes a slit valve.

[0021] The material of the plug body 20 or the bottom wall 22, the shape of the slit 26, etc. can be arbitrarily adopted as long as the ink in the rear shaft 9 does not leak when the slit valve is closed and the ink can be smoothly delivered by the opening of the slit valve. The slit 26 may have other shapes such as a cross shape or a radial shape in addition to a linear shape.

[0022] FIG. 6 is a longitudinal sectional view showing the state before the plug body 20 in FIG. 1 is attached. The plug body 20 is fitted with the rear shaft 9 by being press-fitted into the open end portion 13 of the rear shaft 9. A large-diameter portion 13a is formed on the inner surface of the open end portion 13 of the rear shaft 9. A small-diameter portion 13b having a smaller diameter than the large-diameter portion 13a is formed behind the large-diameter portion 13a. An annular recess 9b is formed in the large-diameter portion 13a. The inner diameter of the large-diameter portion 13a of the rear shaft 9 is slightly smaller than the outer diameter of the large-diameter cylindrical portion 25 of the plug body 20 and slightly larger than the outer diameter of the cylindrical portion 21 of the plug body 20.

[0023] At the time of assembly, after filling the rear shaft 9 with ink, the plug body 20 is fitted to seal the open end portion 13, thereby preventing leakage of the ink during transportation or the like. Specifically, when the plug body 20 is pressed toward the inside of the rear shaft 9 from the state shown in FIG. 6, the tapered portion 24a of the first fitting portion 24 abuts against the open end edge of the open end portion 13, and the first fitting portion 24 is elastically deformed so as to be compressed radially inward. Next, when the plug body 20 is further pressed in a state where the first fitting portion 24 is compressed by the large-diameter portion 13a of the open end portion 13, the first fitting portion 24 reaches the recess 9b beyond the large-diameter portion 13a. Thereby, the first fitting portion 24 is restored, and the first fitting portion 24 fits into the recess 9b. In addition, the large-diameter portion 13a of the open end portion 13 and the large-diameter cylindrical portion 25 are press-fitted and fitted, so that the large-diameter cylindrical portion 25 can be a second fitting portion.

[0024] At this time, the large-diameter cylindrical portion 25 of the plug body 20 is press-fitted into the large-diameter portion 13a of the rear shaft 9. As a result, the plug body 20 is strongly fitted to the inner surface of the opening end portion 13 of the rear shaft 9, preventing the plug body 20 from accidentally falling off. Further, the annular surface 24b of the first fitting portion 24 is locked within the recess 9b. As a result, in addition to the axial resistance due to the press-fitting, the locking of the plug body 20 in the pulling-out direction between the first fitting portion 24 and the recess 9b makes it more difficult for the plug body 20 to fall off. Therefore, the fitting between the rear shaft 9 and the plug body 20 is achieved by at least two fittings: the fitting between the first fitting portion 24 and the recess 9b and the fitting between the large-diameter portion 13a and the large-diameter cylindrical portion 25. Also, the inner diameter of the small-diameter portion 13b of the rear shaft 9 is made slightly smaller than the outer diameter of the cylindrical portion 21 of the plug body 20, and the end portion of the cylindrical portion 21 of the plug body 20 is press-fitted into the small-diameter portion 13b of the rear shaft 9, so that the cylindrical portion 21 becomes the third fitting portion, further making it difficult for the rear shaft 9 and the plug body 20 to fall off.

[0025] FIG. 7 is a longitudinal sectional view showing the state of the ink storage container 10 of FIG. 1, that is, the state before the rear shaft 9 filled with ink is attached, and FIG. 8 is an enlarged sectional view of the portion of the plug body 20 of FIG. 1. As shown in FIG. 7, a female screw portion 8a is formed on the inner surface of the rear end portion of the front shaft 8, and a male screw portion 9a that can be screwed with the female screw portion 8a of the front shaft 8 is formed on the outer surface of the front end portion of the rear shaft 9.

[0026] When the rear shaft 9 is screwed onto the front shaft 8 during the assembly of the writing instrument 1 or the like, that is, when the rear shaft 9 is rotated in one direction with respect to the front shaft 8, the rear shaft 9 gradually advances with respect to the front shaft 8. Due to the advancement of the rear shaft 9 with respect to the front shaft 8, the tip of the cylindrical projection 16 abuts against the bottom wall 22 around the slit 26, and then presses the bottom wall 22 and gradually elastically deforms it. Thereby, the slit 26 is widened. That is, the slit valve is opened. Finally, as shown in FIG. 8, the cylindrical projection 16 penetrates the slit 26, and the screwing of the rear shaft 9 with respect to the front shaft 8 is completed.

[0027] In this state, the communication hole 17 allows the inside and outside of the rear shaft 9 to communicate with each other. As described above, since the relay core member 19 can be impregnated with the ink inside the rear shaft 9, the ink can be supplied to the pen core 7. A seal portion 16a having a larger diameter at the tip, that is, the portion closer to the rear, is formed at the portion of the cylindrical projection 16 closer to the partition wall 15. The outer diameter of the seal portion 16a is formed to be the same as or slightly smaller than the inner diameter of the cylindrical portion 21 of the plug body 20. When the ink storage container 10 is attached, the seal portion 16a of the cylindrical projection 16 fits with the inner surface of the plug body 20, thereby sealing the periphery of the cylindrical projection 16. As a result, the ink in the ink storage container 10 that has flowed into the slit 26 is prevented from leaking forward between the cylindrical projection 16 and the inner surface of the cylindrical portion 21 of the plug body 20.

[0028] When the internal ink is consumed due to use or the like, the rear shaft 9 may be removed from the front shaft 8 for replacement of the ink storage container 10. To release the screwing of the rear shaft 9 with respect to the front shaft 8, when the rear shaft 9 is rotated in the other direction with respect to the front shaft 8, the rear shaft 9 gradually moves backward with respect to the front shaft 8. Due to the backward movement of the rear shaft 9 with respect to the front shaft 8, the tip of the cylindrical projection 16 is pulled out from the slit 26, and the elastic deformation of the slit 26 is restored. Finally, as shown in FIG. 7, the cylindrical projection 16 is detached from the slit 26, and the slit 26 is closed. That is, the slit valve is closed.

[0029] As described above, the attachment and detachment of the rear shaft 9, that is, the attachment and detachment of the ink storage container 10, are performed by screwing and unscrewing. Therefore, it is possible to prevent impacts and the like caused by the sudden movement of the ink storage container 10 in the axial direction during attachment and detachment, and it is possible to prevent the ink filled inside the ink storage container 10 or the remaining ink from splashing. Further, since the inside and the outside of the ink storage container 10 communicate with each other due to the elastic deformation of the slit 26, almost no force associated with the opening and closing of the slit valve is recognized during the screwing process. In addition, since the communication between the inside and the outside of the ink storage container 10 is due to the elastic deformation of the slit 26, the configuration of the slit valve or the plug body 20 is also simple and straightforward. In short, according to the first embodiment, it is possible to provide an ink storage container 10 and a writing instrument 1 including the ink storage container 10 that have a simple configuration and can be easily replaced.

[0030] FIG. 9 is a partial longitudinal sectional view of a writing instrument 100 according to a second embodiment of the present invention, FIG. 10 is an exploded perspective view of the ink storage container 110 of FIG. 9, and FIG. 11 is a longitudinal sectional view of the ink storage container 110 of FIG. 9.

[0031] The writing instrument 100 according to the second embodiment is different only in the shape of the ink storage container 110 and the like as compared with the writing instrument 1 according to the first embodiment. Therefore, members other than the ink storage container 110 of the writing instrument 100, for example, the front shaft 8 and the rear shaft 9, are the same as those of the writing instrument 1. Specifically, in the writing instrument 1 according to the first embodiment, the rear shaft 9 was the container body of the ink storage container 10. The writing instrument 100 according to the second embodiment has a container body 130 of an ink storage container 110 that is separate from the rear shaft 9. That is, the ink storage container 110 is configured as a cartridge so that it can be replaced when the internal ink is consumed by use or the like. By configuring the ink storage container 110 as a cartridge, the total amount of materials to be discarded after use can be reduced as compared with the case where the rear shaft 9 constitutes a part of the ink storage container 10.

[0032] The ink storage container 110 has a cylindrical container body 130 with an open end portion 131 at one end and a closed end portion 132 at the other end, and a plug body 120 that can be fitted to the open end portion 131 of the container body 130. Ink is stored inside the container body 130. The outer diameter of the container body 130 is formed to be slightly smaller than the inner diameter of the rear shaft 9.

[0033] The plug body 120 is a cylindrical member. The plug body 120 has a cylindrical portion 121 configured to fit with the inner surface of the open end portion 131 of the container body 130, and a bottom wall 122 provided at one end of the cylindrical portion 121, that is, the rear end. A linear slit 126 passing through the center of the circular bottom wall 122 is formed in the bottom wall 122. The plug body 120 is formed of a material having rubber elasticity (viscoelasticity), similar to the plug body 20 of the writing instrument 1 according to the first embodiment. Therefore, the plug body 120 or the bottom wall 122 constitutes a slit valve.

[0034] The material of the plug body 120 or the bottom wall 122, the shape of the slit 126, etc. can be arbitrarily adopted as long as the ink in the ink storage container 110 does not leak when the slit valve is closed and the ink can be smoothly delivered by opening the slit valve. The slit 126 may have other shapes such as a cross shape or a radial shape instead of a linear shape.

[0035] The outer diameter of the cylindrical portion 121 of the plug body 120 is slightly larger than the inner diameter of the open end portion 131 of the container body 130. Therefore, at the time of assembly, after filling the container body 130 with ink, the plug body 120 is fitted by press-fitting to seal the open end portion 131, thereby preventing ink leakage during transportation or the like.

[0036] When assembling the writing instrument 100 or the like, for example, hold the front shaft 8 with one hand and hold the ink storage container 110 with the other hand, and insert the ink storage container 110 into the rear end opening of the front shaft 8. At this time, the tip of the cylindrical projection 16 abuts against the bottom wall 122, and then presses the bottom wall 122 to gradually elastically deform it. As a result, the slit 126 is expanded. That is, the slit valve is opened. Finally, the cylindrical projection 16 penetrates the slit 126, and the attachment of the ink storage container 110 to the front shaft 8 is completed. Next, by screwing the rear shaft 9 onto the front shaft 8, the assembly of the writing instrument 100 is completed.

[0037] In this state, the inside and outside of the ink storage container 110 communicate with each other through the communication hole 17, and the relay core member 19 can be impregnated with the ink in the ink storage container 110, so that the ink can be supplied to the writing core 7. The outer diameter of the seal portion 16a of the cylindrical projection 16 is formed to be the same as or slightly smaller than the inner diameter of the cylindrical portion 121 of the plug body 120. When the ink storage container 110 is attached, the seal portion 16a of the cylindrical projection 16 fits with the inner surface of the plug body 120, so that the periphery of the cylindrical projection 16 is sealed. As a result, the ink in the ink storage container 110 that has flowed into the slit 126 is prevented from leaking forward between the cylindrical projection 16 and the inner surface of the cylindrical portion 121 of the plug body 120.

[0038] When the internal ink is consumed by use or the like, the ink storage container 110 may be removed from the front shaft 8 for replacement of the ink storage container 110. By pulling out the ink storage container 110 from the front shaft 8, the tip of the cylindrical projection 16 is pulled out from the slit 126, and the elastic deformation of the slit 126 is restored. As a result, the cylindrical projection 16 is detached from the slit 126, and the slit 126 is closed. That is, the slit valve is closed.

[0039] Since the ink storage container 110 communicates between the inside and the outside due to the elastic deformation of the slit 26, almost no force associated with the opening and closing of the slit valve is recognized during the process of attaching the ink storage container 110. Also, since the communication between the inside and the outside of the ink storage container 110 is due to the elastic deformation of the slit 126, the structure of the slit valve or the plug body 120 is also simple and uncomplicated. In short, according to the second embodiment, it is possible to provide an ink storage container 110 having a simple structure that can be easily replaced and a writing instrument 100 including the ink storage container 110.

[0040] Note that the ink storage container 110 may be configured to be fitted or attached into the rear shaft 9, and the ink storage container 110 may be detached and attached as the rear shaft 9 is screwed to the front shaft 8, similar to the writing instrument 1 according to the first embodiment. Thereby, as described above, it is possible to prevent the ink filled inside the ink storage container 110 or the remaining ink from splashing.

[0041] FIG. 12 is a longitudinal sectional view of a writing instrument 200 according to a third embodiment of the present invention. The writing instrument 200 is a cap-type ballpoint pen of a wick type using a porous body.

[0042] The writing instrument 200 includes a writing instrument body 202 and a cap 3 that can be attached to an end of the writing instrument body 202. A writing core 7 protrudes from the tip of the writing instrument body 202.

[0043] The writing instrument body 202 includes a cylindrical front shaft 208 and a shaft cylinder 211 including a cylindrical rear shaft 9 that is screwed to the inner surface of the rear end portion of the front shaft 208, and a tip member 12 that fits into the front end portion of the front shaft 208. The rear shaft 9 and the tip member 12 are the same as the rear shaft 9 and the tip member 12 of the writing instrument 1 according to the first embodiment. A plug body 220 is fitted to the open end portion 13 of the rear shaft 9. A first wick member 241 impregnated with ink is disposed inside the rear shaft 9. Therefore, the plug body 220 and the rear shaft 9 into which the plug body 220 is fitted constitute an ink storage container 210 as a whole, and the rear shaft 9 constitutes the container body of the ink storage container 210.

[0044] Inside the front shaft 208, a partition wall 215 that divides the inside of the front shaft 208 in the front-rear direction is provided. A cylindrical protrusion 216 that protrudes rearward is formed at the central portion of the partition wall 215. A communication hole 217 that connects the front and rear of the partition wall 215 is defined by the cylindrical protrusion 216. Inside the front shaft 208 in front of the partition wall 215, a second wicking member 242 capable of absorbing ink is disposed. A relay core member 219 is disposed so as to penetrate the center of the second wicking member 242.

[0045] The rear end portion of the relay core member 219 extends beyond the communication hole 217 of the cylindrical protrusion 216 and is inserted into the first wicking member 241 in the rear shaft 9. The front end portion of the relay core member 219 is inserted into the rear end portion of the writing core 7. The relay core member 219 is configured to allow ink to penetrate therein by capillary force. Thereby, the ink in the first wicking member 241 is supplied to the writing core 7 via the relay core member 219, and writing can be performed on the paper surface or the like. Further, the second wicking member 242 houses a low-density wicking member having a lower capillary force than the relay core member 219, and can hold the ink excessively supplied to the relay core member 219. When the ink in the relay core member 219 decreases, the second wicking member 242 can supply ink to the relay core member 219 by capillary force.

[0046] FIG. 13 is a perspective view of the plug body 220 of the writing instrument 200 in FIG. 12, and FIG. 14 is a longitudinal sectional view showing an open state of the slit 226 of the plug body 220 in FIG. 12.

[0047] The plug body 220 is a substantially cylindrical member. The plug body 220 has a cylindrical portion 221, a bottom wall 222 provided at one end of the cylindrical portion 221, that is, the rear end, and a flange portion 223 formed on the outer surface of the other open end of the cylindrical portion 221, that is, the front end. On the outer surface of the cylindrical portion 221, a first fitting portion 224 formed in an annular protrusion shape is formed. On the outer surface of the cylindrical portion 221 behind the first fitting portion 224, a large-diameter cylindrical portion 225 having a larger diameter than the cylindrical portion 221 is formed. The outer diameter of the first fitting portion 224 is slightly larger than the outer diameter of the large-diameter cylindrical portion 225. The bottom wall 222 is formed so as to have a V-shaped cross section by two intersecting planes, and a slit 226 is formed in a portion corresponding to the V-shaped valley.

[0048] Similar to the plug body 20 of the writing instrument 1 according to the first embodiment, the plug body 220 is formed of a material having rubber elasticity (viscoelasticity). In a state where no force is applied to the bottom wall 222, the opposing inner surfaces of the slit 226 are in close contact with each other, and the slit 226 is in a closed state. On the other hand, when a force is applied to expand the V-shaped bottom wall 222, the slit 226, that is, the bottom wall 222 defining the slit 226, elastically deforms to form an opening, and as shown in FIG. 14, the slit 226 is in an open state. Therefore, the plug body 220 or the bottom wall 222 constitutes a slit valve.

[0049] At the time of assembly, after arranging the first wick member 241 impregnated with ink in the rear shaft 9, the plug body 220 is fitted to seal the opening end portion 13, thereby preventing ink leakage during transportation or the like. The fitting of the plug body 220 to the opening end portion 13 of the rear shaft 9 is the same as the fitting of the plug body 20 of the writing instrument 1 according to the first embodiment. In short, the first fitting portion 224 of the plug body 220 fits into the recess 9b of the rear shaft 9 by elastic deformation and restoration, and the large-diameter cylindrical portion 225 of the plug body 220 is press-fitted into the large-diameter portion 13a of the rear shaft 9. As a result, it becomes more difficult for the plug body 220 to fall off.

[0050] FIG. 15 is a longitudinal sectional view showing a state before attachment of the ink storage container 210 of FIG. 12, and FIG. 16 is an enlarged sectional view of a portion of the plug body 220 of FIG. 12.

[0051] The attachment of the ink storage container 210, that is, the screwing and unscrewing of the rear shaft 9 with respect to the front shaft 208, and the opening and closing of the slit valve associated therewith are the same as those of the writing instrument 1 according to the first embodiment. In short, when assembling the writing instrument 200 or the like, when the rear shaft 9 is screwed onto the front shaft 208, the tip of the cylindrical projection 216 abuts against the bottom wall 222 around the slit 226 due to the forward movement of the rear shaft 9 with respect to the front shaft 208, and then presses the bottom wall 222 and gradually elastically deforms it. As a result, the slit 226 is widened. That is, the slit valve is opened. Finally, as shown in FIG. 16, the cylindrical projection 216 penetrates the slit 226, and the screwing of the rear shaft 9 with respect to the front shaft 208 is completed.

[0052] In this state, the inside and outside of the ink storage container 210 communicate with each other through the communication hole 217, and since the relay core member 19 is inserted into the first cotton member 241 impregnated with ink, ink can be supplied to the writing core 7.

[0053] On the other hand, for the replacement of the ink storage container 210, the screwing of the rear shaft 9 with respect to the front shaft 208 is released. Due to the backward movement of the rear shaft 9 with respect to the front shaft 208, the tip of the cylindrical projection 216 is pulled out from the slit 226, and the elastic deformation of the slit 226 is restored. Finally, as shown in FIG. 15, the cylindrical projection 216 is detached from the slit 226, and the slit 226 is closed. That is, the slit valve is closed.

[0054] As described above, the attachment and detachment of the ink storage container 210 are performed by screwing and unscrewing. Therefore, it is possible to prevent impacts and the like caused by sudden movement of the ink storage container 210 in the axial direction during attachment and detachment, and it is possible to prevent the ink filled inside the ink storage container 210 or the remaining ink from splashing. Further, since the inside and the outside of the ink storage container 210 communicate with each other due to the elastic deformation of the slit 226, almost no force associated with the opening and closing of the slit valve is recognized during the screwing process. Also, since the communication between the inside and the outside of the ink storage container 210 is due to the elastic deformation of the slit 226, the configuration of the slit valve or the plug body 220 is also simple and straightforward. In short, according to the third embodiment, it is possible to provide an ink storage container 210 having a simple configuration and capable of being easily replaced, and a writing instrument 200 including the ink storage container 210.

[0055] According to the plug body 220, the shape of the bottom wall 222 is different from that of the plug body 20 of the writing instrument 1 according to the first embodiment. Since the bottom wall 222 is formed so as to have a V-shaped cross section, the slit 226 is configured to be more easily opened than the bottom wall 22 of the plug body 20 formed in a disc shape.

[0056] The plug body 20 of the writing instrument 1 according to the first embodiment and the plug body 220 of the writing instrument 200 according to the third embodiment are provided with a first fitting portion and a flange portion formed in an annular protrusion shape. Although the plug body 220 of the writing instrument 100 according to the second embodiment is not provided with a first fitting portion and a flange portion, at least one of the first fitting portion and the flange portion may be applied to the plug body 220 and fitted to the container body 130. In short, a protrusion-shaped first fitting portion that protrudes outward is formed on the outer surface of the cylindrical portion of the plug body, and a large-diameter portion is formed in front of a recess that fits with the first fitting portion on the inner surface of the container body. When the plug body is fitted to the container body, the first fitting portion may be elastically deformed to overcome the large-diameter portion and be fitted. The second fitting portion may be formed not only in a shape like the large-diameter portion 12a described above but also in an annular protrusion shape like the first fitting portion 24.

[0057] In the above-described embodiments, the cylindrical projection formed on the front shaft side may have any shape or the like as long as it is configured to expand the slit of the ink storage container, and may be provided other than the front shaft. The relay core member may be elastically deformed so as to directly expand the slit without passing through the cylindrical projection and penetrate the slit. In the plug body, the cylindrical portion and the bottom wall may be formed of separate members or by two-color molding or the like. The plug body may be formed in a plate shape or a disc shape having no cylindrical portion but having a slit. In this case, the plate-shaped or disc-shaped plug body may close the opening end portion of the container body by fitting, adhesion, two-color molding, or the like.

[0058] In a direct liquid type writing instrument in which ink is directly filled in an ink storage container, such as the writing instrument 1 according to the first embodiment and the writing instrument 100 according to the second embodiment, and a felt type writing instrument such as the writing instrument 200 according to the third embodiment, the above-described configurations can be arbitrarily combined. For example, a first felt member may be housed in the ink storage container 110 of the writing instrument 100 according to the second embodiment.

[0059] In the above-described embodiments, the container body in contact with the ink is preferably formed of a synthetic resin of polyethylene, polypropylene, or polymethylpentene.

[0060] The ink is preferably a composition containing water, a colorant, and an acetylene glycol-based surfactant or an acetylene alcohol-based surfactant. By including an acetylene glycol-based surfactant or an acetylene alcohol-based surfactant in the ink, the wettability and slipperiness of the ink with respect to a container body formed of polypropylene or polymethylpentene are improved. As a result, the movement of the ink within the ink storage container becomes smooth, and the ink ejection property from the pen tip can be improved. Further, it is preferable that the ink has a contact angle of 40 to 100° and a falling angle of 10 to 65° with respect to a container body formed of polyethylene or polypropylene, and a contact angle of 42 to 90° and a falling angle of 10 to 45° with respect to a container body formed of polymethylpentene. Note that the contact angle and the falling angle can be measured using a contact angle meter (trade name: CA-A, manufactured by Kyowa Interface Science Co., Ltd.). By setting the contact angle and the falling angle within the above ranges, the slipperiness of the ink becomes good, and consequently, the ink ejection property from the pen tip 7 becomes good.

[0061] Regarding the above-described embodiments of the present invention, although the writing instrument has been described using a ballpoint pen, the configuration of the writing instrument according to the above-described embodiments may be applied to other writing instruments using an ink storage container, such as a marking pen. The top crown 5 of the cap 3, a part or all of the shaft cylinder may be used as an erasing portion for erasing the handwriting by the writing instrument. As the ink to be stored in the ink storage container, a thermochromic ink containing a thermochromic coloring material may be employed. In this case, the writing instrument is a thermochromic writing instrument, and the handwriting of the writing instrument can be thermochromically changed by the frictional heat generated when rubbed by a friction body as the erasing portion.

[0062] Here, a thermochromic ink refers to an ink that maintains a predetermined color (first color) at room temperature (e.g., 25°C), changes to another color (second color) when heated up to a predetermined temperature (e.g., 60°C), and then returns to the original color (first color) when cooled down to a predetermined temperature (e.g., -5°C). In a writing instrument using thermochromic ink, the above second color is made colorless, and heating the drawn line written in the first color (e.g., red) to make it colorless is herein referred to as "erasing". Therefore, a friction body is rubbed against the writing surface or the like on which the drawn line is written to generate frictional heat, thereby changing the drawn line to colorless, that is, erasing it. Of course, the above second color may be a colored one other than colorless.

Explanation of Signs

[0063] 1 Writing instrument 2 Writing instrument body 3 Cap 7 Writing core 8 Front shaft 8a Female thread part 9 Rear shaft 9a Male thread part 9b Concave part 10 Ink storage container 11 Shaft cylinder 12 Mouth tip member 12a Large diameter part 13 Open end part 13a Large diameter part 13b Small diameter part 14 Closed end part 15 Partition wall 16 Cylindrical protrusion 17 Communication hole 18 Collector 19 Relay core member 20 Plug body 21 Cylindrical part 22 Bottom wall 23 Flange part 24 First fitting part 24a Tapered part 24b Annular surface 25 Large diameter cylindrical part 26 Slit

Claims

1. A container body having an open end portion at one end and a closed end portion closed at the other end, a plug body provided with a cylindrical portion provided with respect to the container body so as to close the open end portion and configured to fit with the inner surface of the open end portion of the container body, and a bottom wall provided with a slit valve having a slit configured to communicate the inside and outside of the container body by elastic deformation. An ink storage container comprising:

2. A protruding first fitting portion protruding outward is formed on the outer surface of the cylindrical portion of the plug body, and a concave portion fitting with the first fitting portion and a large diameter portion are formed on the inner surface of the container body in front of the concave portion. The ink storage container according to claim 1, wherein when the plug body is fitted to the container body, the first fitting portion is elastically deformed to overcome the large diameter portion and the fitting is made.

3. An ink storage container according to claim 1 or 2, a writing instrument comprising a shaft cylinder having a cylindrical projection configured to expand the slit.

4. The shaft cylinder has a front shaft and a rear shaft, the front shaft has the cylindrical projection, the ink storage container is the rear shaft or a cartridge disposed in the rear shaft, and the front shaft and the rear shaft are screwed together. The writing instrument according to claim 3, wherein, during assembly, as the front shaft and the rear shaft are screwed together, the cylindrical projection gradually expands the slit of the slit valve and is configured to penetrate the slit.

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