Ink accommodating container and writing implement provided with ink accommodating container

Abstract

An ink accommodating container 10 comprises: a rear barrel 9 including, at one end, an open end portion 13 that is open, and, at the other end, a closed end portion 14 that is closed; and a stopper body 20 including a cylinder portion 21 which is provided with respect to the rear barrel 9 so as to close the open end portion 13, and which is configured to be fitted to an inner surface of the open end portion 13 of the rear barrel 9, and a bottom wall 22 which has a slit valve that is provided with a slit 26 configured such that the inside and the outside of the rear barrel 9 communicate with one other as a result of elastic deformation.

Description

Ink container and writing implement equipped with ink container

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

[0002] Writing instruments having ink containers filled with liquid ink are known (for example, see Patent Documents 1 and 2). The ink containers of the writing instruments described in Patent Documents 1 and 2 are configured as cartridges so that they can be replaced when the ink inside is consumed through use. To prevent leakage of the ink inside, the open end of the ink container before replacement is sealed with a disk-shaped stopper in Patent Document 1, and with a spherical stopper in Patent Document 2.

[0003] JP 2011-206982 A JP 2015-120278 A

[0004] The ink containers described in Patent Documents 1 and 2 require the cap to be removed or the cap to be firmly inserted in order to attach them to a writing instrument, making replacement difficult. Furthermore, once the ink container described in Patent Document 1 is unsealed, it is virtually impossible or difficult to reseal. The ink container described in Patent Document 2 requires a spherical cap, a coil spring to support the cap, and a retaining member to lock the cap, making the configuration complex.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide an ink container that has a simple structure and can be easily replaced, and a writing instrument that includes the ink container.

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

[0007] A first fitting portion in the form of a protrusion protruding outward may be formed on the outer surface of the tubular portion of the stopper body, and a recess that fits into the first fitting portion and a large diameter portion forward of the recess may be formed on the inner surface of the container body, and when the stopper body is fitted into the container body, the first fitting portion may elastically deform to overcome the large diameter portion and fit.

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

[0009] The barrel may have a front shaft and a rear shaft, the front shaft having the cylindrical protrusion, and the ink containing container may be the rear shaft or a cartridge disposed within the rear shaft. The front shaft and the rear shaft may be configured to be connected by screwing, and during assembly, the cylindrical protrusion may be configured to gradually widen the slit of the slit valve and pass through the slit as the front shaft and the rear shaft are screwed together.

[0010] According to the aspects of the present invention, a common effect is achieved in that an ink container that has a simple configuration and can be easily replaced and a writing instrument that includes the ink container are provided.

[0011] FIG. 1 is a vertical cross-sectional view of a writing instrument according to a first embodiment of the present invention. FIG. 2 is a perspective view of the stopper of the writing instrument of FIG. 1. FIG. 3 is a front view of the stopper of FIG. 1. FIG. 4 is a cross-sectional view of the stopper taken along line A-A of FIG. 3. FIG. 5 is a vertical cross-sectional view of the stopper of FIG. 1, showing an open state of the slit. FIG. 6 is a vertical cross-sectional view of the stopper of FIG. 1, showing a state before attachment. FIG. 7 is a vertical cross-sectional view of the ink containing container of FIG. 1, showing a state before attachment. FIG. 8 is an enlarged cross-sectional view of a portion of the stopper of FIG. 1. FIG. 9 is a partial vertical cross-sectional view of a writing instrument according to a second embodiment of the present invention. FIG. 10 is an exploded perspective view of the ink containing container of FIG. 9. FIG. 11 is a vertical cross-sectional view of the ink containing container of FIG. 9. FIG. 12 is a vertical cross-sectional view of a writing instrument according to a third embodiment of the present invention. FIG. 13 is a perspective view of the stopper of the writing instrument of FIG. 12. FIG. 14 is a vertical cross-sectional view of the stopper of FIG. 12, showing an open state of the slit. FIG. 15 is a vertical cross-sectional view of the ink containing container of FIG. 12, showing a state before attachment. FIG. 16 is an enlarged cross-sectional view of the plug portion of FIG.

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Corresponding components throughout the drawings are designated by common reference numerals.

[0013] 1 is a vertical cross-sectional view of a writing instrument 1 according to a first embodiment of the present invention. The writing instrument 1 is a cap-type ballpoint pen for ink containing water.

[0014] The writing instrument 1 has a writing instrument body 2 and caps 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 of the cap body 4. A writing lead 7 protrudes from the tip of the writing instrument body 2. In this specification, the side of the writing lead 7 in the axial direction of the writing instrument 1 is defined as the "front" side, and the side opposite the writing lead 7 is defined as the "rear" side. Furthermore, in describing each component, the "front" side and "rear" side are defined in the same way as the writing instrument 1, based on the state in which the component is arranged in the writing instrument 1.

[0015] The writing instrument body 2 has a barrel tube 11 equipped with a cylindrical front barrel 8 and a cylindrical rear barrel 9 that screws onto the inner surface of the rear end of the front barrel 8, and a tip member 12 that fits onto the front end of the front barrel 8. The rear barrel 9 has an open end 13 that is open at one end and a closed end 14 at the other end. A stopper 20 is fitted into the open end 13 of the rear barrel 9. Ink is contained inside the rear barrel 9. Therefore, the stopper 20 and the rear barrel 9 into which the stopper 20 is fitted together constitute an ink containing container 10, and the rear barrel 9 constitutes the container body of the ink containing container 10.

[0016] A partition 15 is provided inside front barrel 8, dividing the interior of front barrel 8 in the front-to-rear direction. A cylindrical protrusion 16 that protrudes rearward is formed in the center of partition 15. Cylindrical protrusion 16 defines a communication hole 17 that connects the front and rear of partition 15. A cylindrical collector 18 with a plurality of fins formed on its outer periphery is disposed inside front barrel 8 in front of partition 15. Collector 18 is configured to send ink from inside rear barrel 9 via communication hole 17 by replacing ink in rear barrel 9, which is the container body, with air drawn in from the outside. A relay core member 19 is disposed so as to pass through the center of collector 18.

[0017] The rear end of the relay core member 19 is disposed within the communication hole 17 of the cylindrical protrusion 16 and can be impregnated with the ink in the rear barrel 9. The front end of the relay core member 19 is inserted into the rear end of the writing lead 7. The relay core member 19 is configured to allow ink to penetrate into the interior by capillary force. This allows the ink in the rear barrel 9 to be supplied to the writing lead 7 via the relay core member 19, allowing writing to be performed on paper or the like.

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

[0019] The plug 20 is a substantially cylindrical member. The plug 20 has a tubular portion 21 configured to fit with the inner surface of the open end 13 of the rear body 9, a bottom wall 22 provided at one end of the tubular portion 21, i.e., the rear end, and a flange portion 23 formed on the outer surface of the other open end of the tubular portion 21, i.e., the front end. A first fitting portion 24 formed as an annular protrusion is formed on the outer surface of the tubular portion 21. A large-diameter tubular portion 25 having a larger diameter than the tubular portion 21 is formed on the outer surface of the tubular portion 21, spaced slightly rearward from the first fitting portion 24. The first fitting portion 24 has a tapered portion 24a tapering toward the rear 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 tubular portion 25. A linear slit 26 passing through the center of the circular bottom wall 22 is formed in the bottom wall 22.

[0020] The plug 20 is made of a material having rubber elasticity (viscoelasticity). For example, the plug 20 is made of nitrile rubber, ethylene propylene diene rubber, or the like. When 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 force is applied to the bottom wall 22, the slit 26, or in other words, the bottom wall 22 defining the slit 26, elastically deforms to form an opening, and the slit 26 is in an open state, as shown in FIG. 5 . Therefore, the plug 20 or the bottom wall 22 constitutes a slit valve.

[0021] The material of the plug 20 or the bottom wall 22 and the shape of the slit 26 may be arbitrarily selected as long as the ink in the rear barrel 9 does not leak out when the slit valve is closed and the ink can be smoothly dispensed when the slit valve is opened. The slit 26 may have any shape other than a straight line, such as a cross or a radial shape.

[0022] Figure 6 is a vertical cross-sectional view showing the plug 20 of Figure 1 in a state before installation. The plug 20 is fitted to the rear body 9 by being press-fitted into the open end 13 of the rear body 9. A large diameter portion 13a is formed on the inner surface of the open end 13 of the rear body 9. A small diameter portion 13b, which is smaller in 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 body 9 is slightly smaller than the outer diameter of the large diameter cylindrical portion 25 of the plug 20 and slightly larger than the outer diameter of the cylindrical portion 21 of the plug 20.

[0023] During assembly, after filling the rear barrel 9 with ink, fitting the plug 20 to seal the open end 13 prevents ink leakage during transportation, etc. Specifically, when the plug 20 is pressed toward the rear barrel 9 from the state shown in FIG. 6 , the tapered portion 24 a of the first fitting portion 24 abuts against the open edge of the open end 13, elastically deforming the first fitting portion 24 so that it is compressed radially inward. Next, when the plug 20 is further pressed while the first fitting portion 24 is compressed by the large-diameter portion 13 a of the open end 13, the first fitting portion 24 passes over the large-diameter portion 13 a and reaches the recess 9 b. This causes the first fitting portion 24 to return to its original shape and fit into the recess 9 b. Furthermore, the large-diameter portion 13 a of the open end 13 and the large-diameter cylindrical portion 25 are press-fitted, and the large-diameter cylindrical portion 25 can serve as a second fitting portion.

[0024] At this time, the large-diameter cylindrical portion 25 of the plug 20 is press-fitted into the large-diameter portion 13a of the rear body 9. As a result, the plug 20 is tightly fitted against the inner surface of the open end 13 of the rear body 9, preventing the plug 20 from unintentionally falling off. Furthermore, 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 caused by the press-fitting, the locking of the first fitting portion 24 and the recess 9b in the direction in which the plug 20 is pulled out makes the plug 20 even more difficult to fall off. Therefore, the plug 20 is fitted to the rear body 9 through fitting at least two points: 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. Furthermore, by making the inner diameter of the small diameter portion 13b of the rear axle 9 slightly smaller than the outer diameter of the tubular portion 21 of the plug body 20 and pressing the end of the tubular portion 21 of the plug body 20 into the small diameter portion 13b of the rear axle 9, the tubular portion 21 becomes a third fitting portion, making it even more difficult for the rear axle 9 and the plug body 20 to fall off.

[0025] Fig. 7 is a vertical cross-sectional view showing ink containing container 10 of Fig. 1, i.e., the state before rear barrel 9 filled with ink is attached, and Fig. 8 is an enlarged cross-sectional view of a portion of stopper 20 of Fig. 1. As shown in Fig. 7, a female thread portion 8a is formed on the inner surface of the rear end of front barrel 8, and a male thread portion 9a that can be threaded with female thread portion 8a of front barrel 8 is formed on the outer surface of the front end of rear barrel 9.

[0026] When assembling the writing instrument 1, for example, the rear barrel 9 is threaded onto the front barrel 8, i.e., when the rear barrel 9 is rotated in one direction relative to the front barrel 8, the rear barrel 9 gradually advances relative to the front barrel 8. As the rear barrel 9 advances relative to the front barrel 8, the tip of the cylindrical projection 16 abuts against the bottom wall 22 around the slit 26, and then presses against the bottom wall 22, gradually deforming it elastically. This forces the slit 26 to expand. In other words, the slit valve opens. Finally, as shown in FIG. 8 , the cylindrical projection 16 passes through the slit 26, completing the threading of the rear barrel 9 onto the front barrel 8.

[0027] In this state, the interior and exterior of the rear barrel 9 are connected by the communication hole 17, and as described above, the relay core member 19 can be impregnated with ink inside the rear barrel 9, allowing ink to be supplied to the writing tip 7. A seal portion 16a is formed in the portion of the cylindrical protrusion 16 closer to the partition wall 15, with a larger diameter than the tip, i.e., the portion closer to the rear. The outer diameter of the seal portion 16a is the same as or slightly smaller than the inner diameter of the tubular portion 21 of the stopper 20. When the ink containing container 10 is attached, the seal portion 16a of the cylindrical protrusion 16 fits into the inner surface of the stopper 20, sealing the periphery of the cylindrical protrusion 16. As a result, ink inside the ink containing container 10 that has flowed into the slit 26 is prevented from leaking forward from between the cylindrical protrusion 16 and the inner surface of the tubular portion 21 of the stopper 20.

[0028] When the ink inside has been consumed through use, the rear barrel 9 may be removed from the front barrel 8 to replace the ink containing container 10. When the rear barrel 9 is rotated in the opposite direction relative to the front barrel 8 to unscrew the rear barrel 9 from the front barrel 8, the rear barrel 9 gradually retracts relative to the front barrel 8. As the rear barrel 9 retracts relative to the front barrel 8, the tip of the cylindrical projection 16 is pulled out of the slit 26, and the elastic deformation of the slit 26 is restored. Eventually, as shown in FIG. 7 , the cylindrical projection 16 disengages from the slit 26, and the slit 26 closes. In other words, the slit valve is closed.

[0029] As described above, the rear barrel 9 is attached and detached, i.e., the ink containing container 10 is attached and detached by screwing and unscrewing. Therefore, it is possible to prevent shocks and the like caused by sudden axial movement of the ink containing container 10 during attachment and detachment, and to prevent the ink filled inside the ink containing container 10 or the remaining ink from scattering. Furthermore, since the ink containing container 10 communicates between the interior and exterior through elastic deformation of the slit 26, the force associated with opening and closing the slit valve during the screwing process is hardly noticeable. Furthermore, since the communication between the interior and exterior of the ink containing container 10 is achieved through elastic deformation of the slit 26, the structure of the slit valve or stopper 20 is simple and straightforward. In short, according to the first embodiment, it is possible to provide an ink containing container 10 and a writing instrument 1 equipped with the ink containing container 10 that are simply configured and can be easily replaced.

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

[0031] The writing instrument 100 according to the second embodiment differs from the writing instrument 1 according to the first embodiment only in the shape of the ink container 110, etc. Therefore, the components of the writing instrument 100 other than the ink container 110, such as the front barrel 8 and rear barrel 9, are the same as those of the writing instrument 1. Specifically, in the writing instrument 1 according to the first embodiment, the rear barrel 9 was the container body of the ink container 10. The writing instrument 100 according to the second embodiment has a container body 130 of the ink container 110 that is separate from the rear barrel 9. In other words, the ink container 110 is configured as a cartridge so that it can be replaced when the ink inside it is consumed through use. By configuring the ink container 110 as a cartridge, the total amount of material discarded after use can be reduced compared to when the rear barrel 9 forms part of the ink container 10.

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

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

[0034] The material of the stopper 120 or the bottom wall 122 and the shape of the slit 126 may be arbitrarily selected as long as the ink in the ink containing container 110 does not leak when the slit valve is closed and the ink can be smoothly delivered when the slit valve is opened. The slit 126 may have any shape other than a straight line, such as a cross or a radial shape.

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

[0036] When assembling the writing instrument 100, for example, the front barrel 8 is held with one hand and the ink containing container 110 is held with the other hand, and the ink containing container 110 is inserted into the rear end opening of the front barrel 8. At this time, the tip of the cylindrical protrusion 16 abuts against the bottom wall 122 and then presses against the bottom wall 122, gradually elastically deforming it. This causes the slit 126 to be pushed open. In other words, the slit valve is opened. Finally, the cylindrical protrusion 16 passes through the slit 126, completing the attachment of the ink containing container 110 to the front barrel 8. Next, the rear barrel 9 is screwed onto the front barrel 8, completing the assembly of the writing instrument 100.

[0037] In this state, the inside and outside of the ink containing container 110 are connected by the communication hole 17, and the relay core member 19 can be impregnated with the ink in the ink containing container 110, allowing ink to be supplied to the writing tip 7. The outer diameter of the seal portion 16a of the cylindrical protrusion 16 is formed to be the same as or slightly smaller than the inner diameter of the tubular portion 121 of the stopper 120. When the ink containing container 110 is attached, the seal portion 16a of the cylindrical protrusion 16 fits into the inner surface of the stopper 120, thereby sealing the periphery of the cylindrical protrusion 16. As a result, ink in the ink containing container 110 that has flowed into the slit 126 is prevented from leaking forward from between the cylindrical protrusion 16 and the inner surface of the tubular portion 121 of the stopper 120.

[0038] When the ink inside the ink container 110 has been consumed through use, the ink container 110 may be removed from the front barrel 8 to replace it. By pulling the ink container 110 out of the front barrel 8, the tip of the cylindrical protrusion 16 is pulled out of the slit 126, and the elastic deformation of the slit 126 is restored. As a result, the cylindrical protrusion 16 is released from the slit 126, and the slit 126 is closed. In other words, the slit valve is closed.

[0039] Because the interior and exterior of the ink containing container 110 are connected by elastic deformation of the slit 126, the force associated with opening and closing the slit valve is hardly noticeable during the process of attaching the ink containing container 110. Furthermore, because communication between the interior and exterior of the ink containing container 110 is achieved by elastic deformation of the slit 126, the structure of the slit valve or stopper 120 is simple and straightforward. In short, according to the second embodiment, it is possible to provide an ink containing container 110 that has a simple structure and can be easily replaced, and a writing instrument 100 that includes the ink containing container 110.

[0040] The ink containing container 110 may be configured to be able to fit into or be attached to the rear barrel 9, and similarly to the writing instrument 1 according to the first embodiment, the ink containing container 110 may be attached or detached as the rear barrel 9 is screwed onto the front barrel 8. This prevents the ink filled or remaining inside the ink containing container 110 from scattering, as described above.

[0041] 12 is a vertical cross-sectional view of a writing instrument 200 according to a third embodiment of the present invention. The writing instrument 200 is a ballpoint pen with a batting and a cap that uses a porous material.

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

[0043] The writing instrument body 202 has a barrel tube 211 equipped with a cylindrical front barrel 208 and a cylindrical rear barrel 9 that screws onto the inner surface of the rear end of the front barrel 208, and a tip member 12 that fits onto the front end of the front barrel 208. The rear barrel 9 and tip member 12 are the same as the rear barrel 9 and tip member 12 of the writing instrument 1 according to the first embodiment. A stopper 220 is fitted into the open end 13 of the rear barrel 9. A first inner batting member 241 impregnated with ink is disposed inside the rear barrel 9. Therefore, the stopper 220 and the rear barrel 9 into which the stopper 220 is fitted together constitute the ink containing container 210, and the rear barrel 9 constitutes the container body of the ink containing container 210.

[0044] A partition wall 215 is provided inside front barrel 208, dividing the interior of front barrel 208 into front and rear sections. A cylindrical protrusion 216 that protrudes rearward is formed in the center of partition wall 215. Cylindrical protrusion 216 defines a communication hole 217 that connects the front and rear of partition wall 215. A second inner batting member 242 that can absorb ink is disposed inside front barrel 208 in front of partition wall 215. A relay core member 219 is disposed so as to pass through the center of second inner batting member 242.

[0045] The rear end of the relay core member 219 extends beyond the communication hole 217 of the cylindrical protrusion 216 and is inserted into the first inner batting member 241 in the rear barrel 9. The front end of the relay core member 219 is inserted into the rear end of the writing core 7. The relay core member 219 is configured to allow ink to penetrate into the interior thereof by capillary force. This allows ink in the first inner batting member 241 to be supplied to the writing core 7 via the relay core member 219, enabling writing on paper or the like. The second inner batting member 242 contains a low-density inner batting member with lower capillary force than the relay core member 219, and is able to retain excess ink supplied to the relay core member 219. When the ink in the relay core member 219 becomes low, the second inner batting member 242 can supply ink to the relay core member 219 by capillary force.

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

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

[0048] Like the stopper 20 of the writing instrument 1 according to the first embodiment, the stopper 220 is formed of a material having rubber elasticity (viscoelasticity). When no force is applied to the bottom wall 222, the opposing inner surfaces of the slit 226 are in close contact, 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, or in other words, the bottom wall 222 defining the slit 226, elastically deforms to form an opening, and the slit 226 is in an open state, as shown in FIG. 14 . Therefore, the stopper 220 or the bottom wall 222 constitutes a slit valve.

[0049] During assembly, after placing the first inner lining member 241 impregnated with ink inside the rear barrel 9, the plug 220 is fitted to seal the open end 13, thereby preventing ink leakage during transport, etc. The fitting of the plug 220 to the open end 13 of the rear barrel 9 is similar to the fitting of the plug 20 of the writing instrument 1 according to the first embodiment. In short, the first fitting portion 224 of the plug 220 elastically deforms and restores its shape, thereby fitting into the recess 9b of the rear barrel 9 and the large-diameter cylindrical portion 225 of the plug 220 being press-fitted into the large-diameter portion 13a of the rear barrel 9. As a result, the plug 220 is more unlikely to fall off.

[0050] 15 is a vertical cross-sectional view showing the ink containing container 210 of FIG. 12 in a state before installation, and FIG. 16 is an enlarged cross-sectional view of the stopper 220 portion of FIG.

[0051] The attachment of the ink containing container 210, i.e., the opening and closing of the slit valve associated with the threading and unthreading of the rear barrel 9 onto the front barrel 208, is the same as in the writing instrument 1 according to the first embodiment. In short, when the rear barrel 9 is threaded onto the front barrel 208 during assembly of the writing instrument 200, the forward movement of the rear barrel 9 relative to the front barrel 208 causes the tip of the cylindrical protrusion 216 to abut against the bottom wall 222 around the slit 226, and then presses against the bottom wall 222, gradually deforming it elastically. This causes the slit 226 to be widened. In other words, the slit valve is opened. Finally, as shown in FIG. 16 , the cylindrical protrusion 216 passes through the slit 226, completing the threading of the rear barrel 9 onto the front barrel 208.

[0052] In this state, the inside and outside of the ink storage container 210 are connected through the communication hole 217, and the relay core member 19 is inserted into the first inner batting member 241 impregnated with ink, making it possible to supply ink to the writing core 7.

[0053] On the other hand, in order to replace the ink containing container 210, the rear barrel 9 is unscrewed from the front barrel 208. As the rear barrel 9 retracts relative to the front barrel 208, the tip of the cylindrical projection 216 is pulled out of the slit 226, and the elastic deformation of the slit 226 is restored. Finally, as shown in FIG. 15 , the cylindrical projection 216 is released from the slit 226, and the slit 226 closes. In other words, the slit valve is closed.

[0054] As described above, the ink containing container 210 is attached and detached by screwing and unscrewing. Therefore, it is possible to prevent shocks and the like caused by sudden axial movement of the ink containing container 210 that accompanies attachment and detachment, and to prevent the ink filled inside the ink containing container 210 or the ink remaining inside the ink containing container 210 from scattering. Furthermore, since the ink containing container 210 communicates between the interior and exterior through elastic deformation of the slit 226, the force associated with opening and closing the slit valve during the screwing process is hardly noticeable. Furthermore, since the communication between the interior and exterior of the ink containing container 210 is achieved through elastic deformation of the slit 226, the configuration of the slit valve or stopper 220 is simple and straightforward. In short, according to the third embodiment, it is possible to provide an ink containing container 210 that is simply configured and can be easily replaced, and a writing instrument 200 equipped with the ink containing container 210.

[0055] The shape of the bottom wall 222 of the stopper 220 is different from that of the stopper 20 of the writing instrument 1 according to the first embodiment. The bottom wall 222 is formed to have a V-shaped cross section, and is therefore configured to make the slit 226 easier to open than the bottom wall 22 of the stopper 20, which is formed in a disk shape.

[0056] The stopper 20 of the writing instrument 1 according to the first embodiment and the stopper 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. The stopper 120 of the writing instrument 100 according to the second embodiment is not provided with a first fitting portion or a flange portion, but at least one of the first fitting portion and the flange portion may be applied to the stopper 120 to fit with the container body 130. In other words, the stopper may have a first fitting portion formed as a protrusion protruding outward on the outer surface of the cylindrical portion, and a large-diameter portion may be formed on the inner surface of the container body forward of the recess that fits with the first fitting portion. When the stopper is fitted to the container body, the first fitting portion may elastically deform to overcome the large-diameter portion and fit. The second fitting portion may be formed not only in a shape like the large-diameter cylindrical portion 25 described above, but also in an annular protrusion shape like the first fitting portion 24.

[0057] In the above-described embodiments, the cylindrical protrusion formed on the front barrel side may have any shape as long as it is configured to push open the slit of the ink containing container, and may be provided on a location other than the front barrel. The relay core member may be elastically deformed to directly push open the slit without using the cylindrical protrusion, and may pass through the slit. In the stopper, the cylindrical portion and bottom wall may be formed as separate members or by two-color molding, etc. The stopper may be formed in a plate or disk shape with a slit, without having a cylindrical portion. In this case, the plate-shaped or disk-shaped stopper may close the open end of the container body by fitting, bonding, two-color molding, etc.

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

[0059] In the above-described embodiment, the container body that comes into contact with the ink is preferably made of synthetic resin such as 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 ink's wettability and slipperiness with respect to a container body made of polypropylene or polymethylpentene are improved. As a result, the ink moves more smoothly within the ink container, improving the ink's ejection performance from the writing tip. Furthermore, the ink preferably has a contact angle of 40 to 100° and a sliding angle of 10 to 65° with respect to a container body made of polyethylene or polypropylene, and a contact angle of 42 to 90° and a sliding angle of 10 to 45° with respect to a container body made of polymethylpentene. The contact angle and sliding angle can be measured using a contact angle meter (product name: CA-A, manufactured by Kyowa Interface Science Co., Ltd.). By keeping the contact angle and sliding angle within the above ranges, the ink's slipperiness is improved, which in turn improves the ink's ejection performance from the writing tip 7.

[0061] Although the above-described embodiments of the present invention have been described using a writing instrument as a ballpoint pen, the configuration of the writing instrument according to the above-described embodiments may also be applied to other writing instruments that use an ink reservoir, such as a marking pen. The crown 5 of the cap 3 and part or all of the barrel may serve as an erasing portion for erasing handwriting made with the writing instrument. Thermochromic ink containing a thermochromic coloring material may be used as the ink contained in the ink reservoir. In this case, the writing instrument is a thermochromic writing instrument, and the handwriting made with the writing instrument can be thermally discolored by the frictional heat generated when rubbed with a friction body serving as the erasing portion.

[0062] Here, thermochromic ink refers to ink that maintains a predetermined color (first color) at room temperature (e.g., 25°C), changes to a different color (second color) when heated to a predetermined temperature (e.g., 60°C), and then returns to the original color (first color) when cooled to a predetermined temperature (e.g., -5°C). In a writing instrument using thermochromic ink, the second color is colorless, and "erasing" refers to heating a line drawn in the first color (e.g., red) to make it colorless. Therefore, a frictional body rubs against the writing surface on which the line was drawn, generating frictional heat, thereby changing the drawn line to colorless, i.e., erasing it. Naturally, the second color may be a color other than colorless.

[0063] REFERENCE SIGNS LIST 1 Writing implement 2 Writing implement body 3 Cap 7 Writing lead 8 Front barrel 8a Female thread portion 9 Rear barrel 9a Male thread portion 9b Recessed portion 10 Ink container 11 Barrel 12 Tip member 13 Open end 13a Large diameter portion 13b Small diameter portion 14 Closed end 15 Partition wall 16 Cylindrical protrusion 17 Communication hole 18 Collector 19 Intermediate lead member 20 Plug 21 Cylindrical portion 22 Bottom wall 23 Flange portion 24 First fitting portion 24a Tapered portion 24b Annular surface 25 Large diameter cylindrical portion 26 Slit

Claims

1. An ink storage container comprising: a container body having an open end portion at one end and a closed end portion at the other end; a cylinder 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 the outside of the container body by elastic deformation.

2. The ink storage container according to claim 1, wherein a protruding first fitting portion is formed on the outer surface of the cylinder portion of the plug body, a recess that fits 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 is elastically deformed to overcome the large-diameter portion and the fitting is made.

3. A writing instrument comprising: the ink storage container according to claim 1 or 2; and a shaft cylinder having a cylindrical protrusion configured to expand the slit.

4. The writing instrument according to claim 3, wherein the shaft cylinder has a front shaft and a rear shaft, the front shaft has the cylindrical protrusion, 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 configured to be connected by screwing. At the time of assembly, with the screwing of the front shaft and the rear shaft, the cylindrical protrusion is configured to gradually expand the slit of the slit valve and penetrate the slit.

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