Writing instrument

Abstract

To provide a direct liquid type writing utensil which can surely prevent the leakage of ink from a pen point even when the ink inside is frozen.SOLUTION: The ink reserving member 4 is equipped with an ink reserving part 40 consisting of an ink reserving groove 43 and an ink guide groove 44. The ink reservoir member 4 is provided with a first lateral hole 46 penetrating in the radial direction and communicating with the inner hole 45. The first horizontal hole 46 and the ink guide groove 44 are formed so as not to communicate with each other in a cross section. A first lateral hole 46 is provided in the rear half of the ink reservoir 40. The ink reservoir member 4 has a second horizontal hole 47 which is arranged in front of the first horizontal hole 46, penetrates in the radial direction, and communicates with the inner hole 45. The first horizontal hole 46 and the second horizontal hole 47 are provided through at least one comb tooth 41 in the axial direction and communicated with the ink reserving groove 43 adjacent to the comb tooth 41.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a writing instrument, specifically a direct ink type writing instrument that includes a pen tip, an ink tank that directly stores ink, an ink reservoir member that has the pen tip at its front end and is located in front of the ink tank to temporarily retain ink that overflows due to an increase in pressure inside the ink tank, and an ink guide member that is located inside the ink reservoir member and supplies ink from the ink tank to the pen tip. This application claims priority to Japanese Patent Application No. 2021-198947, filed on December 8, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, Patent Document 1 discloses a configuration in which a vent hole communicating with a through hole formed in a side portion of an ink reservoir for attaching an ink guide core is provided in the side portion of the ink reservoir. Patent Document 2 discloses a configuration in which a through hole is provided from the outer surface of a collector toward the inner hole of the collector. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4212714 [Patent Document 2] Patent No. 4666872 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, when the ink in the ink chamber freezes (especially when the ink freezes with the pen tip facing downwards), the ink expands in volume in the ink chamber and is forced out through the through hole toward the vicinity of the pen tip, and the forced-out ink cannot be reliably discharged through the vent hole to the outer surface of the ink reservoir, which could result in ink leaking from the pen tip.

[0005] Similarly, in Patent Document 2, when the ink in the ink tank freezes (especially when the ink freezes with the pen tip facing downwards), the ink expands in volume in the ink tank and is forced out through the inner hole toward the vicinity of the pen tip, and the forced-out ink cannot be reliably discharged from the through hole to the outer surface of the collector, which may result in ink leaking from the pen tip.

[0006] The present invention aims to solve the above-mentioned conventional problems by providing a direct-fill writing instrument that can reliably prevent ink leakage from the pen tip even if the ink inside freezes. In the present invention, "front" refers to the pen tip side, and "rear" refers to the opposite side. The definition of directions in the present invention will be described separately later. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides the following means.

[0008] [Aspect 1 of the present invention] A writing implement comprising a pen tip, an ink tank for directly storing ink, an ink retaining member having the pen tip at its front end and disposed in front of the ink tank for temporarily retaining ink that overflows due to an increase in pressure within the ink tank, and an ink guiding member disposed inside the ink retaining member for supplying ink from the ink tank to the pen tip, wherein the ink retaining member has a plurality of plate-like comb teeth formed at intervals on its outer surface, a plurality of ink retaining grooves formed between the comb teeth for temporarily retaining ink, and slit-shaped ink guides extending in the axial direction that communicate with the ink tank and each of the ink retaining grooves. A writing instrument comprising: a guide groove; an ink reservoir section formed on the outer surface in the front-to-back direction, consisting of the ink reservoir groove and the ink guide groove; and an inner hole extending axially and having the ink guide member disposed therein; the ink reservoir member having a first horizontal hole opening radially outward and communicating with the inner hole, and a second horizontal hole positioned forward of the first horizontal hole, opening radially outward and communicating with the inner hole; the first horizontal hole and the ink guide groove being formed so as to be non-communicative in a cross section; the first horizontal hole being formed in the rear half of the ink reservoir section; and the second horizontal hole and the ink guide groove being formed so as to be non-communicative in a cross section.

[0009] According to the writing instrument of the above aspect, even if the ink in the ink tank freezes while the pen tip is facing downward, the ink pushed out from the ink tank can be quickly and reliably discharged to the outside through the first horizontal hole close to the ink tank before it reaches the vicinity of the pen tip, thereby reliably preventing ink leakage from the pen tip when the ink in the ink tank freezes.

[0010] According to the writing instrument of the above aspect, when the ink freezes, the expanded volume of the frozen ink in the ink tank is mainly discharged to the outside through the first horizontal hole, and the expanded volume of the frozen ink inside the inner bore is discharged to the outside through the second horizontal hole. This more reliably prevents ink from leaking from the pen tip when the ink freezes. Furthermore, according to the writing instrument of the above aspect, when ink in the ink tank is first discharged to the pen tip (i.e., during initial ink discharge), residual air inside the inner bore can be reliably discharged to the outside through the second horizontal hole, allowing ink to be quickly discharged from the ink tank to the pen tip.

[0011] [Aspect 2 of the present invention] The writing implement according to Aspect 1, wherein the first horizontal hole is formed through at least one of the comb teeth in the axial direction and communicates with the ink-retaining groove adjacent to the comb tooth.

[0012] According to the writing instrument of the above aspect, a sufficient opening area of ​​the first horizontal hole can be ensured, and ink spilling from the first horizontal hole can be reliably discharged to the outside when the ink freezes. Furthermore, according to the writing instrument of the above aspect, ink spilling from the first horizontal hole can be discharged into the ink reservoir groove when the ink freezes. As a result, when the ink thaws and the pressure inside the ink tank is reduced, the ink in the ink reservoir groove is quickly recovered into the ink tank through the ink guide groove. As a result, ink residue near the first horizontal hole can be prevented.

[0013] [Embodiment 3 of the present invention] 3. The writing implement according to aspect 1 or 2, wherein the second horizontal hole is formed through at least one of the comb teeth in the axial direction and communicates with the ink-retaining groove adjacent to that comb tooth.

[0014] According to the writing instrument of the above aspect, a sufficient opening area of ​​the second horizontal hole can be ensured, and ink spilling from the second horizontal hole can be reliably discharged to the outside when the ink freezes. Furthermore, according to the writing instrument of the above aspect, ink spilling from the second horizontal hole can be discharged to the ink retaining groove when the ink freezes. As a result, when the pressure inside the ink tank is reduced after the ink thaws, the ink in the ink retaining groove is quickly recovered into the ink tank through the ink guide groove. As a result, ink residue near the second horizontal hole can be prevented. In particular, when the first horizontal hole and the second horizontal hole are axially pierced through at least one comb tooth and communicate with the ink retaining groove adjacent to the comb tooth, the following effects can be achieved. That is, when the ink freezes, ink spilling from inside the inner hole can be reliably discharged to the outside, and ink residue near the first horizontal hole and the second horizontal hole can be prevented after the ink thaws.

[0015] [Aspect 4 of the present invention] A writing instrument described in any one of aspects 1 to 3, wherein the first horizontal hole has a first inner opening that opens into the inner hole, a first outer opening that opens radially outward, and a first step portion that is positioned between the first inner opening and the first outer opening and faces radially outward.

[0016] According to the writing instrument of the above aspect, the first step portion can prevent ink that has been discharged from the inner hole to the outside through the first horizontal hole from returning to the inside of the inner hole. This aspect can prevent problems such as ink leaking from the pen tip due to overflowing ink unintentionally returning from the first horizontal hole to the inner hole.

[0017] More specifically, the overflow ink discharged from the inner hole through the first horizontal hole to the outside is prevented from flowing back into the inner hole by the function of the first step portion.The overflow ink is then stably guided from the first horizontal hole through the ink reservoir groove to the ink guide groove by capillary force.The overflow ink is then efficiently collected from the ink guide groove to the ink tank.

[0018] [Embodiment 5 of the present invention] A writing instrument described in any one of aspects 1 to 4, wherein the second horizontal hole has a second inner opening that opens into the inner hole, a second outer opening that opens radially outward, and a second step portion that is positioned between the second inner opening and the second outer opening and faces radially outward.

[0019] According to the writing instrument of the above aspect, the second step portion can prevent ink that has been discharged from the inner hole to the outside through the second horizontal hole from returning to the inside of the inner hole. This aspect can prevent problems such as ink leaking from the pen tip due to overflowing ink unintentionally returning from the second horizontal hole to the inner hole.

[0020] More specifically, the second step prevents overflow ink that has been discharged from the inner hole to the outside through the second horizontal hole from flowing back into the inner hole. The overflow ink then flows steadily from the second horizontal hole through the ink reservoir groove to the ink guide groove by capillary force. The overflow ink is then efficiently collected from the ink guide groove into the ink tank.

[0021] [Aspect 6 of the present invention] A writing implement comprising: a pen tip; an ink tank for directly storing ink; an ink reservoir member having the pen tip at its front end and disposed in front of the ink tank for temporarily storing ink that overflows due to a pressure increase in the ink tank; and an ink guide member disposed inside the ink reservoir member for supplying ink from the ink tank to the pen tip. The ink reservoir member comprises a plurality of plate-like comb teeth formed at intervals on its outer surface, and a plurality of ink guide members formed between the comb teeth for temporarily storing ink. A writing instrument comprising an ink reservoir groove, a slit-shaped ink guide groove extending in the axial direction that communicates with the ink tank and each of the ink reservoir grooves, and an inner hole that penetrates in the axial direction and has the ink guide member disposed inside, wherein the ink reservoir member has a horizontal hole that opens radially outward and communicates with the inner hole, the horizontal hole and the ink guide groove are formed so as not to communicate with each other in cross section, and the horizontal hole penetrates axially through at least one of the comb teeth and communicates with the ink reservoir groove adjacent to the comb tooth.

[0022] According to the writing instrument of the above aspect, a sufficient opening area of ​​the horizontal hole can be ensured, and ink spilling from the horizontal hole can be reliably discharged to the outside when the ink freezes. Furthermore, according to the writing instrument of the above aspect, ink spilling from the horizontal hole can be discharged into the ink reservoir groove when the ink freezes. As a result, when the ink thaws and the pressure inside the ink tank is reduced, the ink in the ink reservoir groove is quickly recovered into the ink tank through the ink guide groove. As a result, ink residue near the horizontal hole can be prevented. Note that in the above aspect, the horizontal hole may be a single hole, or multiple holes may be provided at the front and rear of the ink reservoir section. Furthermore, in the above aspect, the horizontal hole may be formed in any of the front half of the ink reservoir section, the center of the ink reservoir section, or the rear half of the ink reservoir section.

[0023] [Embodiment 7 of the present invention] A writing instrument as described in aspect 6, wherein the horizontal hole has an inner opening that opens into the inner hole, an outer opening that opens radially outward, and a step portion that is positioned between the inner opening and the outer opening and faces radially outward.

[0024] [Embodiment 8 of the present invention] A writing implement comprising: a pen tip; an ink tank for directly storing ink; an ink reservoir member having the pen tip at its front end and disposed in front of the ink tank for temporarily storing ink that overflows due to an increase in pressure within the ink tank; and an ink guide member disposed inside the ink reservoir member for supplying ink from the ink tank to the pen tip, wherein the ink reservoir member has a plurality of plate-like comb teeth formed at intervals on its outer surface, a plurality of ink reservoir grooves formed between the comb teeth for temporarily storing ink, and a plurality of ink reservoir grooves formed between the comb teeth for temporarily storing ink. a slit-shaped ink guide groove extending in the axial direction, which is connected to the ink reservoir grooves and to each of the ink reservoir grooves, and an inner hole extending axially and having the ink guide member disposed therein; the ink reservoir member having a horizontal hole opening radially outward and communicating with the inner hole, the horizontal hole and the ink guide groove being formed so as not to be connected in cross section, and the horizontal hole having an inner opening opening to the inner hole, an outer opening opening radially outward, and a step portion disposed between the inner opening and the outer opening and facing radially outward.

[0025] According to the writing instrument of the above aspect, the step portion can prevent ink that has been discharged from the inner hole to the outside through the horizontal hole from returning to the inside of the inner hole. This aspect can prevent problems such as ink leaking from the pen tip due to overflowing ink unintentionally returning from the horizontal hole to the inner hole.

[0026] Here, conventional writing instruments have room for improvement in terms of efficiently returning spilled ink to the ink tank (hereinafter referred to as another problem). In this regard, with the writing instrument of the above aspect, spilled ink discharged to the outside through the horizontal hole can be efficiently returned to the ink tank. Therefore, the above-mentioned other problem can also be solved. [Effects of the Invention]

[0027] The writing implement of the above aspect of the present invention can reliably prevent ink from leaking from the pen tip even if the ink inside freezes. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a vertical cross-sectional view showing an embodiment of a writing implement according to the present invention. [Figure 2] FIG. 2 is an enlarged longitudinal sectional view showing a main part of FIG. [Figure 3] 3(a) is a cross-sectional view taken along line AA in FIG. 2, FIG. 3(b) is a cross-sectional view taken along line BB in FIG. 2, and FIG. 3(c) is a cross-sectional view taken along line CC in FIG. [Figure 4] FIG. 4 is a vertical cross-sectional view of the ink reservoir member of FIG. [Figure 5] 5(a) is a cross-sectional view taken along line D1-D1 in FIG. 4, and FIG. 5(b) is a cross-sectional view taken along line D2-D2 in FIG. [Figure 6] 6(a) is a cross-sectional view taken along line E1-E1 in FIG. 4, and FIG. 6(b) is a cross-sectional view taken along line E2-E2 in FIG. [Figure 7] 7(a) is a cross-sectional view taken along line F1-F1 in FIG. 4, and FIG. 7(b) is a cross-sectional view taken along line F2-F2 in FIG. [Figure 8] 8(a) is a cross-sectional view taken along line G1-G1 in FIG. 4, and FIG. 8(b) is a cross-sectional view taken along line G2-G2 in FIG. [Figure 9] 9(a) is an enlarged view of part H in FIG. 4, and FIG. 9(b) is an enlarged view of part I in FIG. [Figure 10] FIG. 10 is a side view of the ink reservoir member of FIG. 1, that is, a view of the ink reservoir member as seen from the opening side of the first horizontal hole and the opening side of the second horizontal hole. [Figure 11] 11(a) is an enlarged view of a portion J in FIG. 10, and FIG. 11(b) is an enlarged view of a portion K in FIG. [Figure 12] 12 is a perspective view of the ink reservoir member of FIG. [Figure 13] FIG. 13 is a cross-sectional view taken along line MM in FIG. 10, and includes an enlarged view of FIG. 6(b). [Figure 14] FIG. 14 is a cross-sectional view taken along line NN in FIG. 10, and includes an enlarged view of FIG. 8(b). [Figure 15]FIG. 15 is a cross-sectional view showing an ink reservoir member of a writing implement according to a first modified example of this embodiment, and specifically shows a transverse cross-sectional view corresponding to FIG. [Figure 16] FIG. 16 is a cross-sectional view showing an ink reservoir member of a writing implement according to a first modified example of this embodiment, and specifically shows a transverse cross-sectional view corresponding to FIG. [Figure 17] Figure 17(a) is a side view showing a part of the ink reservoir member of the writing implement of the second modified example of this embodiment, specifically a side view corresponding to Figure 11(a). Figure 17(b) is a side view showing another part of the ink reservoir member of the writing implement of the second modified example of this embodiment, specifically a side view corresponding to Figure 11(b). [Figure 18] Figure 18(a) is a cross-sectional view showing a part of the ink reservoir member of a writing implement according to a second modified example of this embodiment, specifically a longitudinal cross-sectional view corresponding to Figure 9(a). Figure 18(b) is a cross-sectional view showing another part of the ink reservoir member of a writing implement according to a second modified example of this embodiment, specifically a longitudinal cross-sectional view corresponding to Figure 9(b). DETAILED DESCRIPTION OF THE INVENTION

[0029] A writing instrument 1 according to an embodiment of the present invention is shown in FIGS. As shown in Figure 1, writing instrument 1 of this embodiment has a generally cylindrical or columnar shape centered on central axis O. Specifically, writing instrument 1 has a generally cylindrical or columnar shape. Note that in this embodiment, central axis O may be omitted from illustration in some drawings.

[0030] 1 and 2, the writing instrument 1 comprises a nib 3, an ink reservoir member 4 having the nib 3 at its front end, a barrel 2 having the ink reservoir member 4 disposed inside the front portion, an ink tank 21 disposed behind the ink reservoir member 4 inside the barrel 2, and an ink guide member 5 disposed inside the ink reservoir member 4. The nib 3, ink reservoir member 4, barrel 2, ink tank 21, and ink guide member 5 are arranged coaxially with one another, with a common central axis O.

[0031] The definitions of directions used in this embodiment will be described below. In this embodiment, the direction in which the central axis O of the writing instrument 1 extends, i.e., the direction along the central axis O, is referred to as the front-rear direction. The front-rear direction may also be referred to as the axial direction or the longitudinal direction. In the front-rear direction (axial direction, longitudinal direction), the ink tank 21 and the nib 3 are disposed at different positions. In the front-rear direction, the direction from the ink tank 21 to the nib 3 is referred to as the front side, and the direction from the nib 3 to the ink tank 21 is referred to as the rear side. The front side may also be referred to as one axial side or one longitudinal side. The rear side may also be referred to as the other axial side or the other longitudinal side.

[0032] The direction perpendicular to the central axis O is called the radial direction. Within the radial direction, the direction approaching the central axis O is called the radially inward direction, and the direction away from the central axis O is called the radially outward direction. The direction of rotation around the central axis O is called the circumferential direction.

[0033] Each component of the writing instrument 1 will now be described in detail. Pen tip The pen tip 3 is located at the front end of the writing instrument 1. The pen tip 3 extends in the front-to-rear direction. Examples of the pen tip 3 include a ballpoint pen tip with a rotatable ball at the front end, a pen body made of a processed fiber or porous material, a metal pen body with a slit at the front end like a fountain pen, or a pen body made of an extruded synthetic resin with an axial capillary gap. The pen tip 3 of this embodiment includes a ballpoint pen tip 31 and a tip holder 32 that holds the ballpoint pen tip 31. A first relay core 31a is provided within the ballpoint pen tip 31, and a second relay core 32a is provided within the tip holder 32. The rear end of the first relay core 31a is connected to the front end of the second relay core 32a, and the rear end of the second relay core 32a is connected to the front end of the ink guide member 5. The first relay core 31a and the second relay core 32a are members having capillary gaps in the axial direction, and are made of, for example, an extruded synthetic resin body, a processed fiber body, or a porous body.

[0034] ·Shaft cylinder The barrel 2 is arranged in a portion of the writing instrument 1 other than the front end. The barrel 2 extends in the front-to-rear direction. The barrel 2 is a bottomed cylindrical body with an open front end and a closed rear end, and is obtained by injection molding of a synthetic resin (e.g., polypropylene). An ink reservoir member 4 is arranged inside the front part of the barrel 2. An ink tank 21 is formed inside the barrel 2 behind the ink reservoir member 4. Liquid ink is stored directly inside the ink tank 21. The ink is, for example, a water-based ink, and has the property of freezing when its temperature drops to a predetermined temperature.

[0035] Ink reservoir material The ink reservoir member 4 is disposed between the pen tip 3 and the ink tank 21 in the front-to-rear direction. Specifically, the ink reservoir member 4 is provided behind the pen tip 3 and in front of the ink tank 21. The ink reservoir member 4 is substantially cylindrical and extends in the front-to-rear direction. The ink reservoir member 4 is a member that can temporarily store and hold ink that has overflowed from the ink tank 21. In this embodiment, ink that has overflowed from the ink tank 21 may be referred to as overflowed ink.

[0036] The ink retaining member 4 includes a nib holder 42 disposed at the front end of the ink retaining member 4, a plurality of substantially disc-shaped comb teeth 41 disposed rearward of the nib holder 42, an inner hole 45 formed at the axial center of the ink retaining member 4 and penetrating the ink retaining member 4 in the axial direction, a cylindrical portion 49 to which the plurality of comb teeth 41 are connected, a plurality of ink retaining grooves 43 that temporarily retain ink, an ink guide groove 44 that communicates with the ink tank 21, the ink retaining portion 40, and horizontal holes 46, 47. In this embodiment, the ink retaining member 4 has a plurality of horizontal holes 46, 47. The plurality of horizontal holes 46, 47 includes a first horizontal hole 46 and a second horizontal hole 47 disposed forward and spaced apart from the first horizontal hole 46.

[0037] The pen tip 3 is fixed to the pen tip holder 42. The pen tip holder 42 has an attachment hole that communicates with the inner hole 45, and the pen tip 3 is press-fitted and fixed into the attachment hole. Specifically, a tip holder 32 that holds a ballpoint pen tip 31 is press-fitted and fixed into the attachment hole. An ink guide member 5 is inserted into the inner hole 45. In other words, the ink guide member 5 is provided inside the inner hole 45.

[0038] The ink reservoir member 4 is an injection-molded body of synthetic resin (for example, ABS resin), and the comb teeth 41 and the pen tip holder 42 are integrally formed. The ink reservoir member 4 has the function of temporarily retaining excess ink (overflowed ink) from the ink tank 21 when the pressure inside the ink tank 21 increases. The ink reservoir member 4 also has the function of returning the temporarily retained ink (overflowed ink) to the ink tank 21 when the pressure inside the ink tank 21 decreases.

[0039] The tube portion 49 has a cylindrical shape centered on the central axis O and extends in the front-to-rear direction. The front end of the tube portion 49 is connected to the rear end of the pen tip holding portion 42. The inner hole 45 passes through the tube portion 49 in the front-to-rear direction.

[0040] Each of the multiple comb teeth 41 has a plate shape extending in a direction perpendicular to the central axis O. A pair of plate surfaces of each comb tooth 41 faces the front and rear sides. The multiple comb teeth 41 are formed on the outer surface of the ink reservoir member 4 at intervals from each other in the front-to-rear direction. The comb teeth 41 have a flange shape extending radially outward from the outer peripheral surface of the tubular portion 49. In other words, the radially inner ends of the comb teeth 41 are connected to the outer peripheral surface of the tubular portion 49.

[0041] The comb teeth 41 are arranged at appropriate intervals in the front-rear direction, and ink reservoir grooves 43 are formed between the comb teeth 41. Each of the comb teeth 41 has a slit-shaped ink guide groove 44 that penetrates the axial direction and opens radially outward. The ink guide grooves 44 provided in each comb tooth 41 are arranged side by side in the front-rear direction. In this embodiment, the overall shape of the ink guide grooves 44 arranged in the front-rear direction may be referred to as (one) ink guide groove 44. The ink guide groove 44 is connected to each of the ink reservoir grooves 43 and extends in the axial direction. As shown in FIGS. 13 and 14 , the radial inner end of the ink guide groove 44 is located radially inward from the outer circumferential surface of the cylindrical portion 49. That is, the ink guide groove 44 penetrates each comb tooth 41 in the front-rear direction, is recessed radially inward from the outer circumferential surface of the cylindrical portion 49, and extends in the front-rear direction.

[0042] As shown in FIG. 2 , an ink reservoir section 40 consisting of an ink reservoir groove 43 and an ink guide groove 44 is formed on the outer surface of the ink reservoir member 4. The ink reservoir section 40 is formed on the outer surface of the ink reservoir member 4 in the front-to-rear direction. Specifically, the ink reservoir section 40 is disposed on the outer surface of the ink reservoir member 4 except for the nib holder section 42 located at the front end. In other words, the ink reservoir section 40 is disposed on the outer surface of the ink reservoir member 4 in the portion covered by the barrel 2. The ink guide groove 44 does not communicate with the inner bore 45. In other words, the ink guide groove 44 is not communicated with the inner bore 45. In this embodiment, "the ink guide groove 44 is not communicated with the inner bore 45" means that the ink guide groove 44 and the inner bore 45 are not connected to each other in a cross section (transverse cross section) perpendicular to the central axis O, as shown in FIGS. 3( a) and 3(b), for example. Furthermore, in the description of each component below, "non-communicating" may also have the same meaning as above.

[0043] 5 to 8 and 12, an air alternating groove 48 is formed in each of the multiple comb teeth 41 at a position symmetrical about the axis (180 degrees opposite) to the ink guide groove 44. The air alternating groove 48 penetrates each comb tooth 41 in the axial direction and opens radially outward. The air alternating grooves 48 of the multiple comb teeth 41 are arranged side by side in the front-to-rear direction. In this embodiment, "axially symmetrical (180 degrees opposite)" means that a pair of components (for example, the above-mentioned air alternating groove 48 and ink guide groove 44) are arranged at positions that are rotationally symmetrical about the central axis O by 180 degrees.

[0044] 2 and 3(a), a substantially disk-shaped rear flange 41a is formed at the rear end of the group of comb teeth 41 of the ink reservoir member 4. The rear flange 41a is flange-shaped and extends radially outward from the outer circumferential surface of the cylindrical portion 49.

[0045] The rear flange 41a has an ink guide groove 44 that communicates with the ink reservoir groove 43 in front and with the ink tank 21 in the rear. The ink guide groove 44 of the rear flange 41a is formed axially and opens radially outward, not communicating with the inner hole 45. When the ink reservoir member 4 is inserted into the front opening of the barrel 2, the outer peripheral surface of the rear flange 41a fits into the front inner peripheral surface of the barrel 2, while the group of comb teeth 41 in front of the rear flange 41a remains disengaged from the inner wall of the barrel 2. Therefore, gaps are provided between the outer ends of the multiple comb teeth 41 and the inner peripheral surface of the barrel 2, allowing fluids such as ink and air to flow through. The outer peripheral surface of the rear flange 41a is fitted into the front inner peripheral surface of the barrel 2, causing the rear flange 41a to shrink and deform radially inward. Accordingly, the groove width, i.e., the circumferential dimension, of the ink guide groove 44 of the rear flange 41a is made smaller than the groove width of the ink guide grooves 44 of the comb teeth 41 forward of the rear flange 41a.

[0046] As shown in Figures 2 and 3(b), a substantially circular plate-shaped intermediate flange 41b is formed in the intermediate portion of the group of comb teeth 41 of the ink reservoir member 4. The intermediate portion of the group of comb teeth 41 specifically refers to the intermediate portion of the group of comb teeth 41 in the front-to-rear direction, and more specifically refers to the portion located between the front end of the group of comb teeth 41 and the rear end of the group of comb teeth 41. The intermediate flange 41b has a flange shape that extends radially outward from the outer peripheral surface of the tubular portion 49. At least a portion of the outer peripheral surface of the intermediate flange 41b is located radially outward from the outer ends of the comb teeth 41. In this embodiment, the outer diameter of the intermediate flange 41b is larger than the outer diameter of each comb tooth 41.

[0047] The intermediate flange 41b has an ink guide groove 44 and two air alternating grooves 48 formed on both circumferential sides of the ink guide groove 44 so as to straddle the ink guide groove 44. The ink guide groove 44 is formed axially through the intermediate flange 41b, opens radially outward, and is not connected to the inner hole 45. The two air alternating grooves 48 are formed axially through the intermediate flange 41b, and open radially outward. The two air alternating grooves 48 of the intermediate flange 41b are located at different circumferential positions from the air alternating grooves 48 of each comb tooth 41. The outer surface of the intermediate flange 41b is fitted to the inner surface of the barrel 2.

[0048] 2 and 3(c), a substantially disk-shaped front flange 41c is formed at the front end of the group of comb teeth 41 of the ink reservoir member 4. At least a portion of the outer peripheral surface of the front flange 41c is located radially outward from the outer ends of the comb teeth 41. In this embodiment, the outer diameter of the front flange 41c is larger than the outer diameter of each comb tooth 41.

[0049] The front flange 41c has an air alternating groove 48 formed therein that penetrates in the axial direction and opens radially outward. The air alternating groove 48 of the front flange 41c is formed on the same side as the air alternating grooves 48 of the comb teeth 41 other than those of the intermediate flange 41b. More specifically, the air alternating groove 48 of the front flange 41c and the air alternating grooves 48 of each comb tooth 41 are arranged to overlap when viewed from the front-rear direction. The air alternating groove 48 of the front flange 41c is located at the same circumferential position as the air alternating grooves 48 of each comb tooth 41. No ink guide groove 44 is formed in the front flange 41c.

[0050] Ink guide member The ink guide member 5 has an axial capillary gap and guides ink from the ink tank 21 to the pen tip 3. That is, the ink guide member 5 supplies ink from the ink tank 21 to the pen tip 3. The ink guide member 5 is made of, for example, an extruded synthetic resin, a fiber-processed body, or a porous body. The ink guide member 5 connects the interior of the ink tank 21 to the pen tip 3. The ink guide member 5 may be configured as a single member or multiple members. The ink guide member 5 may protrude rearward into the ink tank 21. That is, the ink guide member 5 may protrude rearward beyond the rear end surface of the ink reservoir member 4, with a portion (rear end) of the ink guide member 5 being located within the ink tank 21. Alternatively, a separate ink guide member connected to the ink guide member 5 in the inner bore 45 may be located within the ink tank 21.

[0051] First transverse hole 4, 6, and 13, a first horizontal hole 46 that opens radially outward and communicates with the inner hole 45 is formed on the outer surface of the ink reservoir member 4. The first horizontal hole 46 penetrates at least the peripheral wall of the tubular portion 49 in the radial direction. The first horizontal hole 46 is formed at a position axially symmetrical to the ink guide groove 44 (i.e., 180 degrees opposite). The first horizontal hole 46 and the ink guide groove 44 are formed so as not to communicate with each other in cross section.

[0052] As shown in FIG. 2, the first horizontal hole 46 is formed in the rear half of the ink reservoir section 40. Preferably, the longitudinal distance L1 from the rear end of the ink reservoir section 40 to the rear end of the first horizontal hole 46 is set in the range of 5% to 45% of the overall length L of the ink reservoir section 40. In this embodiment, the overall length L corresponds to the longitudinal distance from the front end of the ink guide groove 44 to the rear end of the ink guide groove 44. Preferably, the distance L1 is set in the range of 15% to 30% of the overall length L. For example, when the overall length L of the ink reservoir section 40 is set to 30 mm, the longitudinal distance L1 from the rear end of the ink reservoir section 40 to the rear end of the first horizontal hole 46 is set in the range of 1.5 mm to 13.5 mm (preferably 4.5 mm to 9 mm). The rear half of the ink reservoir section 40 refers to the area rearward of the midpoint of the overall length L of the ink reservoir section 40. In other words, the rear half of the ink reservoir section 40 refers to a portion of the ink reservoir section 40 that is located rearward of the center (midpoint) in the front-to-rear direction.

[0053] 6, 9(a), 11(a), and 13, the first horizontal hole 46 is formed axially through a plurality of (specifically, three) comb teeth 411 arranged in the axial direction and opens radially outward. The first horizontal hole 46 communicates with a plurality of (specifically, four) ink retaining grooves 431, 431a adjacent to each comb tooth 411 in front of and behind which the first horizontal hole 46 is formed.

[0054] As shown in FIG. 11(a), the opening of the first horizontal hole 46 has a rectangular shape when viewed from the radially outward direction. The opening of the first horizontal hole 46 has a longitudinal length S1 of 1 to 2 mm and a widthwise (anti-longitudinal) length T1 of 1 to 2 mm, for example. In this embodiment, the widthwise direction may be referred to as the short-side direction or the circumferential direction. The lengths S1 and T1 correspond to the opening dimensions of the portion of the first horizontal hole 46 that opens into the inner hole 45 (first inner opening 46a, described below). The longitudinal length S1 of the opening of the first horizontal hole 46 is the sum of the plate thickness of the three comb teeth 411 that form the first horizontal hole 46 and the groove width (axial dimension) of the two ink-retaining grooves 431a formed by the three comb teeth 411. The area of ​​the opening of the first horizontal hole 46 is, for example, 1 mm. 2~4mm 2 The widthwise length T1 of the opening of first horizontal hole 46 is set, for example, in the range of 60% to 85% (preferably 65% ​​to 80%) of the inner diameter of inner hole 45. The shape of the opening of first horizontal hole 46 may be a rectangle, a circle, an ellipse, a square, or another quadrilateral shape, or a polygon other than a rectangle.

[0055] The first horizontal hole 46 may be configured to penetrate at least one comb tooth 411 in the axial direction and open radially outward. The first horizontal hole 46 may be configured to communicate with the ink retaining groove 431, 431a adjacent to the front or rear of the at least one comb tooth 411 having the first horizontal hole 46. Preferably, the first horizontal hole 46 may be configured to communicate with a plurality of ink retaining grooves 431, 431a adjacent to the front and rear of the at least one comb tooth 411 having the first horizontal hole 46. In other words, the first horizontal hole 46 is configured to penetrate at least one comb tooth 411 (41) in the axial direction and communicate with the ink retaining groove 431, 431a (43) adjacent to the comb tooth 411.

[0056] 4 and 5, a shallow groove region 43a is provided in the vicinity of the rear flange 41a on the side having the ink guide groove 44 in the circumferential direction, where the radial depth of the ink retaining groove 43 gradually becomes shallower toward the rear. This increases the area of ​​the inner wall of the ink guide groove 44 near the ink tank 21, enabling smooth ink flow to and from the ink tank 21. In addition, a first horizontal hole 46 is formed in the ink retaining groove 43 forward of the shallow groove region 43a. As a result, when the ink freezes, the ink flow path in the ink guide groove 44 in the shallow groove region 43a is tightly closed by the frozen ink, and the expanded volume of the frozen ink in the ink tank 21 is smoothly discharged from the inner hole 45 through the first horizontal hole 46 to the outside (ink retaining section 40).

[0057] As shown in FIGS. 5 to 8 and 12, an air alternating groove 48 is formed in each of the comb teeth 41, 411, 412, penetrating the comb teeth 41 in the axial direction. The air alternating groove 48 is formed in a location of each of the comb teeth 41, 411, 412 excluding the ink guide groove 44 (specifically, at a position symmetrical about the axis of the ink guide groove 44). As shown in FIG. 6(a), the first horizontal hole 46 is radially connected to the air alternating groove 48. As shown in FIG. 11(a), the air alternating groove 48 radially connected to the first horizontal hole 46 is formed at the same circumferential position as the air alternating groove 48 formed in the comb tooth 41 adjacent to the comb tooth 411 having the first horizontal hole 46 (i.e., at a position symmetrical about the axis of the ink guide groove 44). This facilitates the manufacture of a mold for molding the ink retention member 4.

[0058] Second transverse hole 4, 8, and 14, a second horizontal hole 47 that communicates with the inner hole 45 and opens radially outward is formed on the outer surface of the ink retention member 4 forward of the first horizontal hole 46. The second horizontal hole 47 penetrates at least the peripheral wall of the tubular portion 49 in the radial direction. The second horizontal hole 47 is formed at a position axially symmetrical to the ink guide groove 44 (i.e., 180 degrees opposite). The second horizontal hole 47 and the ink guide groove 44 are formed so as not to communicate with each other in cross section.

[0059] As shown in Fig. 8(a), the second horizontal hole 47 is radially connected to the air alternating groove 48. As shown in Fig. 11(b), the air alternating groove 48 that is radially connected to the second horizontal hole 47 is formed at the same circumferential position as the air alternating groove 48 formed in the comb tooth 41 adjacent to the comb tooth 412 that has the second horizontal hole 47 (i.e., at a position axially symmetrical to the ink guide groove 44). This makes it easier to manufacture the mold for molding the ink retention member 4.

[0060] As shown in Fig. 2, the second horizontal hole 47 is formed in the front half of the ink reservoir section 40. The longitudinal distance L2 from the rear end of the first horizontal hole 46 to the rear end of the second horizontal hole 47 is set to 30% or more (preferably 40% or more) of the overall length L of the ink reservoir section 40. The front half of the ink reservoir section 40 refers to the part forward of the midpoint of the overall length L of the ink reservoir section 40. In other words, the front half of the ink reservoir section 40 refers to the part of the ink reservoir section 40 that is located forward of the center (midpoint) in the front-to-rear direction.

[0061] 8, 9(b), 11(b), and 14, the second horizontal holes 47 are formed axially through a plurality of (specifically, two) comb teeth 412 arranged in the axial direction and open radially outward. The second horizontal holes 47 communicate with a plurality of (specifically, three) ink retaining grooves 432, 432a adjacent to the front and rear of each comb tooth 412 in which the second horizontal holes 47 are formed.

[0062] As shown in FIG. 11(b), the opening of the second horizontal hole 47 has a rectangular shape when viewed from the radially outward direction. The opening of the second horizontal hole 47 has a longitudinal length S2 of 1 to 2 mm and a widthwise (anti-longitudinal) length T2 of 1 to 2 mm. The lengths S2 and T2 correspond to the opening dimensions of the portion of the second horizontal hole 47 that opens into the inner hole 45 (a second inner opening 47a, described below). The longitudinal length S2 of the opening of the second horizontal hole 47 is the sum of the plate thickness of the two comb teeth 412 that form the second horizontal hole 47 and the groove width (axial dimension) of one ink-retaining groove 432a formed by the two comb teeth 412. The longitudinal length S2 of the opening of the second horizontal hole 47 is set to be greater than the groove width of the ink-retaining groove 432a in which the second horizontal hole 47 is formed. The opening area of ​​the second horizontal hole 47 is, for example, 1 mm 2 ~4mm 2 The widthwise length T2 of the opening of second horizontal hole 47 is set, for example, in the range of 60% to 85% (preferably 65% ​​to 80%) of the inner diameter of inner hole 45. The shape of the opening of second horizontal hole 47 may be a rectangle, a circle, an ellipse, a square, or another quadrilateral shape, or a polygon other than a rectangle.

[0063] The second horizontal hole 47 may be configured to penetrate at least one comb tooth 412 in the axial direction and to open radially outward. The second horizontal hole 47 may be configured to communicate with the ink retaining groove 432, 432a adjacent to the front or rear of at least one comb tooth 412 having the second horizontal hole 47. Preferably, the second horizontal hole 47 may be configured to communicate with a plurality of ink retaining grooves 432, 432a adjacent to the front and rear of at least one comb tooth 412 having the second horizontal hole 47. In other words, the second horizontal hole 47 is configured to penetrate at least one comb tooth 412 (41) in the axial direction and to communicate with the ink retaining groove 432, 432a (43) adjacent to the comb tooth 412.

[0064] The configuration of the horizontal holes 46 and 47 will now be described in more detail. As shown in Figures 13 and 14, the horizontal holes 46, 47 have inner openings 46a, 47a that open to the inner hole 45, outer openings 46b, 47b that open radially outward, and step portions 46c, 47c that are positioned between the inner openings 46a, 47a and the outer openings 46b, 47b and face radially outward.

[0065] Specifically, as shown in FIG. 13, the first horizontal hole 46 has a first inner opening 46a that opens into the inner hole 45, a first outer opening 46b that opens radially outward, and a first step portion 46c that is disposed between the first inner opening 46a and the first outer opening 46b and faces radially outward.

[0066] The first inner opening 46a is disposed at the radially inner end of the first horizontal hole 46 and is connected to the inner hole 45. The first outer opening 46b is disposed radially outward of the first inner opening 46a and is connected to the air exchange groove 48 and the ink retention grooves 431, 431a. In this embodiment, the widthwise (circumferential) dimension of the first outer opening 46b is greater than the widthwise dimension (length T1) of the first inner opening 46a. Furthermore, the longitudinal (front-rear) dimension of the first outer opening 46b is the same as the longitudinal dimension (length S1) of the first inner opening 46a.

[0067] The first step portions 46c connect the first inner opening 46a and the first outer opening 46b. In this embodiment, a pair of first step portions 46c are provided on both ends in the width direction (circumferential direction) of the inner wall of the first horizontal hole 46. The pair of first step portions 46c are arranged on a pair of long sides of the four sides of the first horizontal hole 46, which has a rectangular opening shape, and extend in the axial direction (see FIG. 11(a)).

[0068] The pair of first step portions 46c each have a planar shape that extends in a direction perpendicular to the predetermined radial direction in which the first horizontal hole 46 extends. However, this is not limited to this, and although not specifically shown, the pair of first step portions 46c may each have a planar shape that extends radially outward as they move away from each other in the width direction and is inclined with respect to the predetermined radial direction. Alternatively, the pair of first step portions 46c may each have a planar shape that extends radially inward as they move away from each other in the width direction and is inclined with respect to the predetermined radial direction. Furthermore, the first step portions 46c are not limited to a planar shape, and may have a convex curved shape, a concave curved shape, or the like.

[0069] As shown in FIG. 14, the second horizontal hole 47 has a second inner opening 47a that opens into the inner hole 45, a second outer opening 47b that opens radially outward, and a second step portion 47c that is disposed between the second inner opening 47a and the second outer opening 47b and faces radially outward.

[0070] The second inner opening 47a is disposed at the radially inner end of the second horizontal hole 47 and is connected to the inner hole 45. The second outer opening 47b is disposed radially outward of the second inner opening 47a and is connected to the air exchange groove 48 and the ink retaining grooves 432, 432a. In this embodiment, the widthwise (circumferential) dimension of the second outer opening 47b is greater than the widthwise dimension (length T2) of the second inner opening 47a. Furthermore, the longitudinal (front-rear) dimension of the second outer opening 47b is the same as the longitudinal dimension (length S2) of the second inner opening 47a.

[0071] The second step portions 47c connect the second inner opening 47a and the second outer opening 47b. In this embodiment, a pair of second step portions 47c are provided on both ends in the width direction (circumferential direction) of the inner wall of the second horizontal hole 47. The pair of second step portions 47c are arranged on a pair of long sides of the four sides of the second horizontal hole 47, which has a rectangular opening shape, and extend in the axial direction (see FIG. 11(b)).

[0072] The pair of second step portions 47c each have a planar shape that extends in a direction perpendicular to the predetermined radial direction in which the second horizontal hole 47 extends. However, the pair of second step portions 47c are not limited to this, and although not particularly shown, the pair of second step portions 47c may each have a planar shape that extends radially outward as they move away from each other in the width direction and is inclined with respect to the predetermined radial direction. Alternatively, the pair of second step portions 47c may each have a planar shape that extends radially inward as they move away from each other in the width direction and is inclined with respect to the predetermined radial direction. Furthermore, the second step portions 47c are not limited to a planar shape, and may have a convex curved shape, a concave curved shape, or the like.

[0073] As explained above, the writing instrument 1 of this embodiment is a writing instrument 1 comprising: a pen tip 3; an ink tank 21 for directly storing ink; an ink retaining member 4 having the pen tip 3 at its front end and disposed in front of the ink tank 21 for temporarily retaining ink that overflows as the pressure in the ink tank 21 increases; and an ink guiding member 5 disposed inside the ink retaining member 4 for supplying ink from the ink tank 21 to the pen tip 3. The ink retaining member 4 comprises a plurality of plate-like comb teeth 41 formed at intervals on its outer surface, a plurality of ink retaining grooves 43 formed between the comb teeth 41 for temporarily retaining ink, and a plurality of ink guide members 5 disposed in front of the ink retaining member 4. The writing instrument 1 comprises an ink guide groove 44, which is axially extending and slit-shaped, and which communicates with the ink tank 21 and each of the ink reservoir grooves 43; an ink reservoir section 40 formed in the front-to-rear direction on the outer surface and consisting of the ink reservoir groove 43 and the ink guide groove 44; and an inner hole 45 extending axially and having an ink guide member 5 disposed therein; the ink reservoir member 4 has a first horizontal hole 46 that opens radially outward and communicates with the inner hole 45; the first horizontal hole 46 and the ink guide groove 44 are formed so as not to be connected in cross section; and the first horizontal hole 46 is disposed in the rear half of the ink reservoir section 40.

[0074] As a result, even if the ink in the ink tank 21 freezes while the pen tip 3 is facing downward, the writing instrument 1 of this embodiment can reliably discharge the ink pushed out of the ink tank 21 quickly to the outside (ink reservoir 40) through the first horizontal hole 46 close to the ink tank 21 before it reaches the vicinity of the pen tip 3. As a result, it is possible to reliably prevent ink from leaking from the pen tip 3 when the ink in the ink tank 21 freezes.

[0075] In the writing instrument 1 of this embodiment, the ink reservoir member 4 is positioned forward of the first horizontal hole 46 and has a second horizontal hole 47 that opens radially outward and communicates with the inner hole 45, and the second horizontal hole 47 and the ink guide groove 44 are formed so as not to be connected in cross section.

[0076] As a result, in the writing instrument 1 of this embodiment, when the ink freezes, the expanded volume of the frozen ink in the ink tank 21 is mainly discharged to the outside through the first horizontal hole 46, and the expanded volume of the frozen ink inside the inner bore 45 is discharged to the outside through the second horizontal hole 47. As a result, ink leakage from the nib 3 when the ink freezes can be more reliably prevented. Furthermore, in the writing instrument 1 of this embodiment, when ink in the ink tank 21 is initially discharged to the nib 3 (i.e., during initial ink discharge), residual air inside the inner bore 45 can be reliably discharged to the outside through the second horizontal hole 47, allowing ink to be quickly discharged from the ink tank 21 to the nib 3. The writing instrument 1 of this embodiment may be configured to have only the first horizontal hole 46, but it is preferable to have the second horizontal hole 47.

[0077] In the writing instrument 1 of this embodiment, the first horizontal hole 46 is provided to penetrate at least one comb tooth 411 in the axial direction and communicates with the ink retaining grooves 431, 431a adjacent to the comb tooth 411. Specifically, the first horizontal hole 46 is provided to penetrate a plurality of comb teeth 411 in the axial direction and communicates with a plurality of ink retaining grooves 431, 431a adjacent to the front and rear of each comb tooth 411.

[0078] As a result, the writing instrument 1 of this embodiment can ensure a sufficient opening area for the first horizontal hole 46, and can reliably discharge ink spilling from the first horizontal hole 46 to the outside when the ink freezes. Furthermore, the writing instrument 1 of this embodiment can discharge ink spilling from the first horizontal hole 46 to the ink retaining grooves 431, 431a (specifically, multiple ink retaining grooves 431, 431a) when the ink freezes. As a result, when the pressure inside the ink tank 21 is reduced after the ink thaws, the ink in the ink retaining grooves 431, 431a is quickly recovered into the ink tank 21 through the ink guide groove 44. As a result, ink residue near the first horizontal hole 46 can be prevented.

[0079] In the writing instrument 1 of this embodiment, the second horizontal hole 47 is provided to penetrate at least one comb tooth 412 in the axial direction and communicates with the ink retaining grooves 432, 432a adjacent to the comb tooth 412. Specifically, the second horizontal hole 47 is provided to penetrate a plurality of comb teeth 412 in the axial direction and communicates with a plurality of ink retaining grooves 432, 432a adjacent to the front and rear of each comb tooth 412.

[0080] As a result, the writing instrument 1 of this embodiment can ensure a sufficient opening area for the second horizontal hole 47, and can reliably discharge ink spilling from the second horizontal hole 47 to the outside when the ink freezes. Furthermore, the writing instrument 1 of this embodiment can discharge ink spilling from the second horizontal hole 47 to the ink retaining grooves 432, 432a (specifically, multiple ink retaining grooves 432, 432a) when the ink freezes. As a result, when the pressure inside the ink tank 21 is reduced after the ink thaws, the ink in the ink retaining grooves 432, 432a is quickly recovered into the ink tank 21 through the ink guide groove 44. As a result, ink residue near the second horizontal hole 47 can be prevented.

[0081] In particular, in the writing instrument 1 of this embodiment, the first horizontal hole 46 and the second horizontal hole 47 are formed to axially penetrate at least one comb tooth 41 and communicate with the ink reservoir groove 43 adjacent to the comb tooth 41. This ensures that ink spilling out of the inner hole 45 can be reliably discharged to the outside when the ink freezes, and prevents ink from remaining near the first horizontal hole 46 and the second horizontal hole 47 after the ink thaws.

[0082] In the writing instrument 1 of this embodiment, the first horizontal hole 46 has a first inner opening 46a that opens into the inner hole 45, a first outer opening 46b that opens radially outward, and a first step portion 46c that is positioned between the first inner opening 46a and the first outer opening 46b and faces radially outward.

[0083] As a result, in writing instrument 1 of this embodiment, first step portion 46c can prevent ink that has been discharged from inner hole 45 to the outside through first horizontal hole 46 from returning to the inside of inner hole 45. This embodiment can prevent problems such as ink leaking from pen tip 3 due to overflowing ink unintentionally returning from first horizontal hole 46 to inner hole 45.

[0084] 13, the ink flow is shown by the arrows. More specifically, the overflowing ink discharged from the inner hole 45 through the first horizontal hole 46 to the outside is prevented from flowing back into the inner hole 45 by the function of the first step portion 46c. The overflowing ink is then stably guided from the first horizontal hole 46 through the ink reservoir grooves 431, 431a to the ink guide groove 44 by capillary force. The overflowing ink is efficiently collected from the ink guide groove 44 to the ink tank 21.

[0085] In the writing instrument 1 of this embodiment, the second horizontal hole 47 has a second inner opening 47a that opens into the inner hole 45, a second outer opening 47b that opens radially outward, and a second step portion 47c that is positioned between the second inner opening 47a and the second outer opening 47b and faces radially outward.

[0086] As a result, in writing instrument 1 of this embodiment, second step portion 47c can prevent ink that has been discharged from inner hole 45 to the outside through second horizontal hole 47 from returning to the inside of inner hole 45. This embodiment can prevent problems such as ink leaking from pen tip 3 due to overflowing ink unintentionally returning from second horizontal hole 47 to inner hole 45.

[0087] 14, the ink flow is shown by the arrows. More specifically, the overflowing ink discharged from the inner hole 45 through the second horizontal hole 47 to the outside is prevented from flowing back into the inner hole 45 by the function of the second step portion 47c. The overflowing ink is then stably guided from the second horizontal hole 47 through the ink reservoir grooves 432, 432a to the ink guide groove 44 by capillary force. The overflowing ink is efficiently collected from the ink guide groove 44 to the ink tank 21.

[0088] The writing instrument 1 of this embodiment is a writing instrument 1 comprising a pen tip 3, an ink tank 21 that directly stores ink, an ink retaining member 4 that has the pen tip 3 at its front end and is provided in front of the ink tank 21 and temporarily retains ink that overflows due to a pressure increase inside the ink tank 21, and an ink guiding member 5 that is provided inside the ink retaining member 4 and supplies ink from the ink tank 21 to the pen tip 3. The ink retaining member 4 comprises a plurality of plate-like comb teeth 41 formed at intervals on its outer surface, a plurality of ink retaining grooves 43 formed between the comb teeth 41 and that temporarily retain ink, and The writing instrument 1 comprises an ink guide groove 44, which is a slit extending in the axial direction and communicates with the ink tank 21 and each of the ink retaining grooves 43, and an inner hole 45, which penetrates in the axial direction and has an ink guide member 5 disposed therein, the ink retaining member 4 has horizontal holes (first horizontal hole 46 and / or second horizontal hole 47) which open radially outward and communicate with the inner hole 45, the horizontal holes 46, 47 and the ink guide groove 44 are formed so as not to communicate with each other in cross section, and the horizontal holes 46, 47 penetrate at least one comb tooth 41 in the axial direction and communicate with the ink retaining groove 43 adjacent to the comb tooth 41. Specifically, the horizontal holes 46, 47 penetrate a plurality of comb teeth 41 in the axial direction and communicate with a plurality of ink retaining grooves 43 adjacent to the front and rear of each comb tooth 41.

[0089] As a result, the writing instrument 1 of this embodiment can ensure sufficient opening area for the horizontal holes 46, 47, and can reliably discharge ink spilling from the horizontal holes 46, 47 to the outside when the ink freezes. Furthermore, the writing instrument 1 of this embodiment can discharge ink spilling from the horizontal holes 46, 47 to the ink retaining grooves 43 (specifically, multiple ink retaining grooves 43) when the ink freezes. As a result, when the pressure inside the ink tank 21 is reduced after the ink thaws, the ink in the ink retaining grooves 43 is quickly recovered into the ink tank 21 through the ink guide groove 44. As a result, ink residue near the horizontal holes 46, 47 can be prevented.

[0090] In the present embodiment, the number and positions of the horizontal holes 46, 47 are not limited to those described above. That is, the number and positions of the horizontal holes 46, 47 that axially penetrate at least one comb tooth 41 and communicate with the ink retaining groove 43 adjacent to the comb tooth 41 are not limited to those described above. For example, the present embodiment may include a configuration in which the horizontal holes are provided at two locations, front and rear, a configuration in which only one horizontal hole is provided in the rear half of the ink retaining section 40, a configuration in which only one horizontal hole is provided in the center of the ink retaining section 40, or a configuration in which only one horizontal hole is provided in the front half of the ink retaining section 40.

[0091] In the writing instrument 1 of this embodiment, the horizontal holes 46, 47 have inner openings 46a, 47a that open to the inner hole 45, outer openings 46b, 47b that open radially outward, and step portions 46c, 47c that are positioned between the inner openings 46a, 47a and the outer openings 46b, 47b and face radially outward.

[0092] The writing instrument 1 of this embodiment is a writing instrument 1 comprising a pen tip 3, an ink tank 21 that directly stores ink, an ink retaining member 4 that has the pen tip 3 at its front end and is provided in front of the ink tank 21 and temporarily retains ink that overflows due to a pressure increase inside the ink tank 21, and an ink guiding member 5 that is provided inside the ink retaining member 4 and supplies ink from the ink tank 21 to the pen tip 3, wherein the ink retaining member 4 comprises a plurality of plate-like comb teeth 41 formed at intervals on its outer surface, a plurality of ink retaining grooves 43 formed between the comb teeth 41 and that temporarily retain ink, and an ink guide member 5 that communicates with the ink tank 21 and each of the ink retaining grooves 43. The writing instrument (1) comprises an ink guide groove (44) in the form of a slit extending in the axial direction, and an inner hole (45) that penetrates in the axial direction and has an ink guide member (5) disposed therein; the ink reservoir member (4) has horizontal holes (first horizontal hole (46) and / or second horizontal hole (47)) that open radially outward and communicate with the inner hole (45); the horizontal holes (46, 47) and the ink guide groove (44) are formed so as not to communicate with each other in cross section; and the horizontal holes (46, 47) have inner openings (46a, 47a) that open to the inner hole (45), outer openings (46b, 47b) that open radially outward, and stepped portions (46c, 47c) that are located between the inner openings (46a, 47a) and the outer openings (46b, 47b) and face radially outward.

[0093] As a result, in writing instrument 1 of this embodiment, stepped portions 46c, 47c can prevent ink that has been discharged from inner hole 45 to the outside through horizontal holes 46, 47 from returning to the inside of inner hole 45. This embodiment can prevent problems such as ink leaking from pen tip 3 due to overflowing ink unintentionally returning from horizontal holes 46, 47 to inner hole 45.

[0094] Here, conventional writing instruments have room for improvement in terms of efficiently returning spilled ink to the ink tank (hereinafter referred to as another problem). In this regard, according to the writing instrument 1 of this embodiment, spilled ink discharged to the outside from the horizontal holes 46, 47 can be efficiently returned to the ink tank 21. Therefore, the other problem can also be solved.

[0095] Next, a writing instrument 1 according to a first modified example of this embodiment will be described with reference to Figures 15 and 16. Figure 15 is a cross-sectional view showing the ink reservoir member 4 of the writing instrument 1 according to the first modified example, specifically a horizontal cross-sectional view corresponding to Figure 13. Figure 16 is a cross-sectional view showing the ink reservoir member 4 of the writing instrument 1 according to the first modified example, specifically a horizontal cross-sectional view corresponding to Figure 14. In the illustrations of the modifications described below, the same components as those in the above-described embodiment are given the same reference numerals, and differences will mainly be described below.

[0096] In this first modified example, as shown in Fig. 15 , the radially inner end of the first step portion 46c of the first horizontal hole 46 is connected to the inner circumferential surface of the inner hole 45. Therefore, the first inner opening 46a is located at the ridge portion where the inner circumferential surface of the inner hole 45 and the first step portion 46c are connected. Furthermore, as shown in Fig. 16 , the radially inner end of the second step portion 47c of the second horizontal hole 47 is connected to the inner circumferential surface of the inner hole 45. Therefore, the second inner opening 47a is located at the ridge portion where the inner circumferential surface of the inner hole 45 and the second step portion 47c are connected.

[0097] In this first modified example, the same effects as those of the above-described embodiment can be obtained. Furthermore, in the first modified example, the shape of the mold for molding the ink reservoir member 4 can be simplified.

[0098] Next, with reference to Figures 17 and 18, a writing instrument 1 according to a second modified example of this embodiment will be described. Figure 17(a) is a side view showing a portion of the ink reservoir member 4 of the writing instrument 1 according to the second modified example, specifically a side view corresponding to Figure 11(a). Figure 17(b) is a side view showing a portion of the ink reservoir member 4 of the writing instrument 1 according to the second modified example, specifically a side view corresponding to Figure 11(b). Figure 18(a) is a cross-sectional view showing a portion of the ink reservoir member 4 of the writing instrument 1 according to the second modified example, specifically a vertical cross-sectional view corresponding to Figure 9(a). Figure 18(b) is a cross-sectional view showing a portion of the ink reservoir member 4 of the writing instrument 1 according to the second modified example, specifically a vertical cross-sectional view corresponding to Figure 9(b).

[0099] In this second modified example, as shown in FIGS. 17(a) and 18(a), the first transverse hole 46 has four first step portions 46c, one pair at each widthwise (circumferential) end of the inner wall of the first transverse hole 46 and one pair at each axial (front-rear) end of the inner wall. The four first step portions 46c are located on all four sides of the first transverse hole 46, which has a rectangular opening shape. As shown in FIGS. 17(b) and 18(b), the second transverse hole 47 has four second step portions 47c, one pair at each widthwise (circumferential) end of the inner wall of the second transverse hole 47 and one pair at each axial (front-rear) end of the inner wall. The four second step portions 47c are located on all four sides of the second transverse hole 47, which has a rectangular opening shape.

[0100] In this second modified example, the same effects as those of the above-described embodiment can be obtained. Furthermore, in the second modified example, the overflowing ink discharged from the inner hole 45 to the outside (ink reservoir 40) through the horizontal holes 46 and 47 can be more stably prevented from flowing back into the inner hole 45.

[0101] The present invention may be combined with the various configurations described in the above-described embodiments and modifications, and may also include additions, omissions, substitutions, and other modifications, without departing from the spirit of the present invention. The present invention is not limited to the above-described embodiments, but is limited only by the scope of the claims. [Industrial Applicability]

[0102] According to the writing instrument of the present invention, even if the ink inside freezes, it is possible to reliably prevent ink from leaking from the pen tip, and therefore the writing instrument has industrial applicability. [Explanation of symbols]

[0103] 1 writing implements 2 shaft cylinder 21 Ink Tank 3. Pen tip 31 Ballpoint pen tip 31a First relay core 32 Chip holder 32a Second relay core 4 Ink reservoir member 40 Ink reservoir 41 Comb Teeth 411 Comb teeth 412 Comb teeth 41a Rear end flange 41b Middle collar 41c Front end flange 42 Pen tip holder 43 Ink reservoir groove 431 Ink reservoir groove 431a Ink reservoir groove 432 Ink reservoir groove 432a Ink reservoir groove 43a Shallow trench area 44 Ink guide groove 45 inner hole 46 First transverse foramen (transverse foramen) 46a 1st inner opening (inner opening) 46b 1st outer opening (outer opening) 46c First step (step) 47 Second transverse foramen (transverse foramen) 47a 2nd inner opening (inner opening) 47b 2nd outer opening (outer opening) 47c Second step (step) 48 Air Alternating Groove 49 Cylinder part 5 Ink guide member O center axis

Claims

1. The pen tip and An ink tank that directly stores ink, an ink reservoir member having the pen tip at its front end and disposed in front of the ink tank, for temporarily retaining ink that overflows due to an increase in pressure within the ink tank; an ink guide member provided inside the ink reservoir member and supplying ink from the ink tank to the pen tip, The ink reservoir member is a plurality of plate-like comb teeth formed at intervals on the outer surface; a plurality of ink retaining grooves formed between the comb teeth for temporarily retaining ink; an ink guide groove having a slit shape extending in the axial direction, the ink guide groove communicating with the ink tank and each of the ink reservoir grooves; an ink reservoir portion formed on an outer surface in the front-rear direction and including the ink reservoir groove and the ink guide groove; an inner hole extending in the axial direction and having the ink guide member disposed therein; the ink reservoir member includes a first horizontal hole that opens radially outward and communicates with the inner hole, and a second horizontal hole that is disposed forward of the first horizontal hole, that opens radially outward, and communicates with the inner hole, the first horizontal hole and the ink guide groove are formed so as not to communicate with each other in a cross section, and the first horizontal hole is provided in a rear half of the ink reservoir portion, A writing implement characterized in that the second horizontal hole and the ink guide groove are formed so as not to communicate with each other in cross section.

2. 2. The writing implement according to claim 1, wherein the first horizontal hole is formed through at least one of the comb teeth in the axial direction and communicates with the ink reservoir groove adjacent to the comb tooth.

3. 2. The writing implement according to claim 1, wherein the second horizontal hole is formed through at least one of the comb teeth in the axial direction and communicates with the ink reservoir groove adjacent to the comb tooth.

4. The first transverse hole is a first inner opening portion that opens into the inner hole; a first outer opening portion that opens radially outward; The writing implement according to claim 1 , further comprising: a first step portion disposed between the first inner opening and the first outer opening and facing radially outward.

5. The second horizontal hole is a second inner opening that opens into the inner hole; a second outer opening portion that opens radially outward; The writing implement according to claim 1 , further comprising: a second step portion disposed between the second inner opening and the second outer opening and facing radially outward.

6. The pen tip and An ink tank that directly stores ink, an ink reservoir member having the pen tip at its front end and disposed in front of the ink tank, for temporarily retaining ink that overflows due to an increase in pressure within the ink tank; an ink guide member provided inside the ink reservoir member and supplying ink from the ink tank to the pen tip, The ink reservoir member is a plurality of plate-like comb teeth formed at intervals on the outer surface; a plurality of ink retaining grooves formed between the comb teeth for temporarily retaining ink; an ink guide groove having a slit shape extending in the axial direction, the ink guide groove communicating with the ink tank and each of the ink reservoir grooves; an inner hole extending in the axial direction and having the ink guide member disposed therein; the ink reservoir member has a horizontal hole that opens radially outward and communicates with the inner hole, the horizontal hole and the ink guide groove are formed so as not to communicate with each other in a cross section, The horizontal hole is formed through at least one of the comb teeth in the axial direction and communicates with the ink retaining groove adjacent to the comb tooth.

7. The horizontal hole is an inner opening portion that opens into the inner hole; an outer opening portion that opens radially outward; 7. The writing implement according to claim 6, further comprising a step portion disposed between the inner opening and the outer opening and facing radially outward.

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