Perpetual Pen

Abstract

To provide a fountain pen that can quickly supply ink to a writing area, supply a sufficient amount of ink that does not run out of ink, and suppress ink dripping.SOLUTION: The fountain pen includes a first ink groove 12A and a second ink groove 12B that extend in parallel with each other in the axial direction and meet at the front end side, and a gas-liquid groove 14 that communicates with an ink storage area at the rear end and communicates with the outside at the front end. The first ink groove 12A is opened at the bottom of the gas-liquid groove 14 over a predetermined length in the longitudinal direction of the groove. Assuming that the capillary force per unit area in the cross section of the first ink groove 12A is F1, the capillary force per unit area in the cross section of the second ink groove 12B is F2, and the capillary force per unit area at the opening of the first ink groove 12A provided at the bottom of the gas-liquid groove 14 is F3, the fountain pen satisfies the relation F1>F2>F3.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a fountain pen provided with ink grooves that supply ink to a writing area by capillary force. [Background technology]

[0002] Fountain pens with ink grooves that supply ink to a writing area by capillary force are widely used. Among them, a writing instrument with three ink grooves instead of the usual one has been proposed (see, for example, Patent Document 1). With this writing instrument, more ink can be supplied to the writing area compared to a writing instrument with one ink groove, so that ink shortage can be prevented even when a pen tip for writing bold characters is used. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 9-95083 Summary of the Invention [Problem to be solved by the invention]

[0004] In the writing instrument described in Patent Document 1, the cross-sectional size of the ink grooves on both sides of the three ink grooves is almost the same as that of normal ink grooves. The cross-sectional size of the central ink groove is even larger because it communicates with the comb groove. Therefore, the time it takes for ink to reach the writing area by capillary force from a state where there is no ink in the ink groove is the same as in the case of a conventional ink groove having only one ink groove. Therefore, it may take a certain amount of time for the ink groove to become usable from a state where there is no ink in the ink groove, such as when the writing instrument is first used or after it has been washed. In addition, the center of the pen core of the writing instrument described in Cited Document 1 has an air groove that communicates with the three ink grooves. If a large amount of ink is supplied to the writing area from the three ink grooves, there is a risk of so-called ink dripping.

[0005] Therefore, the object of the present invention is to solve the above-mentioned problems and to provide a fountain pen that can quickly supply ink to the writing area when there is no ink in the ink groove, making it usable, and can supply a sufficient amount of ink to the writing area so that the ink does not run out when in use, and can suppress so-called ink dripping. [Means for solving the problem]

[0006] A fountain pen according to one embodiment of the present invention comprises: A pen core partially covered with a nib, a barrel having an ink reservoir area therein, the barrel being fitted with the pen core at a neck portion; a first ink groove and a second ink groove, the first ink groove and the second ink groove communicating with the ink storage area at their rear ends and extending side by side in the axial direction and joining each other at their front ends; a gas-liquid groove communicating with the ink storage area at a rear end and communicating with the outside at a front end; Equipped with the first ink groove is open to a bottom of the gas-liquid groove over a predetermined length in the longitudinal direction of the groove, F1 is a capillary force per unit area in a cross section of the first ink groove, F2 is a capillary force per unit area in a cross section of the second ink groove; If the capillary force per unit area at the opening of the first ink groove provided at the bottom of the gas-liquid groove is F3, F1 > F2 > F3 The above relationship exists. Effect of the Invention

[0007] The present invention makes it possible to provide a fountain pen that can quickly supply ink to the writing area when there is no ink in the ink groove, making it usable, and can supply a sufficient amount of ink to the writing area so that the ink does not run out when in use, and can suppress so-called ink dripping. [Brief description of the drawings]

[0008] [Figure 1] 1 is a plan cross-sectional view showing a schematic diagram of the overall structure of a fountain pen according to one embodiment of the present invention. [Diagram 2] 2 is an enlarged plan view showing a pen core portion of the fountain pen shown in FIG. 1. [Diagram 3] FIG. 2 is a diagram showing a schematic outline of a first ink groove, a second ink groove, and a gas-liquid groove. [Figure 4A] FIG. 2 is a diagram showing a schematic diagram of the fluid flow in the first ink groove, the second ink groove, and the gas-liquid groove, illustrating the state before the ink flows out of the ink storage area. [Figure 4B] FIG. 2 is a diagram showing a schematic diagram of fluid flows in the first ink groove, the second ink groove, and the gas-liquid groove, showing the state where ink starts to flow in the first ink groove. [Figure 4C] FIG. 2 is a diagram showing a schematic diagram of fluid flows in the first ink groove, the second ink groove, and the gas-liquid groove, illustrating the state where ink has begun to flow into the second ink groove as well. [Figure 4D] FIG. 2 is a diagram showing a schematic diagram of fluid flows in the first ink groove, the second ink groove, and the gas-liquid groove, illustrating the state where ink has reached the front end of the first ink groove. [Figure 4E] FIG. 2 is a diagram showing a schematic diagram of the fluid flow in the first ink groove, the second ink groove, and the gas-liquid groove, in which the ink has reached the front end of the second ink groove. [Figure 4F] FIG. 13 is a diagram showing a schematic diagram of fluid flows in the first ink groove, the second ink groove, and the gas-liquid groove, in which ink has also flowed into the gas-liquid groove, blocking the flow of air. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment for carrying out the present invention will be described with reference to the drawings. Note that the writing implement described below is intended to embody the technical concept of the present invention, and unless otherwise specified, the present invention is not limited to the following. In each drawing, the same reference numerals may be used to designate components having the same functions. The size and positional relationship of components shown in each drawing may be exaggerated for clarity. In this specification, "front" refers to the tip side of the writing instrument, and "rear" refers to the opposite side.

[0010] (A fountain pen according to one embodiment of the present invention) First, an overview of a fountain pen according to one embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a plan sectional view that shows a schematic overall structure of a fountain pen according to one embodiment of the present invention. Figure 2 is an enlarged plan view of a pen core portion of the fountain pen shown in Figure 1. Figure 2 (a) shows the plan view, (b) shows the AA cross section of (a), and (c) shows the BB cross section of (a). The fountain pen 2 of this embodiment comprises a nib 4, a pen core 10 partially covered by the nib 4, and a barrel 20 that fits with the pen core 10 at a neck portion 22 and has an ink storage area 30 inside.

[0011] The pen tip 4 has a pen point, which is the front end that comes into contact with the paper when writing, a slit that extends a specified distance rearward from the pen point, and a hole provided approximately in the center of the pen tip 4. The area near the pen point is the writing area. Since the pen tip 4 requires elasticity and corrosion resistance, the body is made of a gold alloy or special steel, and a wear-resistant alloy is used for the pen point that comes into contact with the paper. The barrel 20 is composed of, for example, a neck 22 located at the front, a barrel 24 located in the center, and a tail plug 26 located at the rear. The neck 22 and barrel 24 are detachably attached to each other by screwing or the like. An ink storage area 30 that stores ink is disposed inside the barrel 20, mainly in the area of ​​the barrel 24. The ink storage area 30 corresponds to an ink cartridge in the case of a cartridge-type fountain pen, and corresponds to a storage section that stores bottled ink sucked up by the converter in the case of a converter-type fountain pen. The barrel 20 can be formed, for example, from a resin material.

[0012] The pen tip 4 and the pen core 10 are overlapped and fitted into the cylindrical neck 22. At this time, the pen tip 4 is arranged to extend forward from the area where it overlaps with the pen core 10. The pen core 10 is arranged to extend rearward from the area where it overlaps with the pen tip 4. In other words, a part of the pen core 10 is covered by the pen tip 4. Since the area where the pen tip 4 and the pen core 10 overlap is fitted into the neck 22, a structure is obtained in which the pen tip 4 and the pen core 10 are firmly fixed to the front end of the barrel 20.

[0013] The pen core 10 is provided with ink grooves 12 for allowing ink in an ink storage area 30 located on the rear end side to flow to the writing area at the front end of the pen tip 4. In particular, in this embodiment, the ink grooves 12 include a first ink groove 12A and a second ink groove 12B that communicate with the ink storage area 30 at the rear end, extend side by side in the axial direction, and merge at the front end side. A merged ink groove 12C where the first ink groove 12A and the second ink groove 12B merge is terminated at the front end of the pen core 10. In addition, a comb groove 16 that temporarily stores ink drawn from the ink storage area 30 is also provided.

[0014] Furthermore, there is provided an air-liquid groove 14 that communicates with the ink storage area 30 at its rear end and with the outside at its front end. If ink flows out of the ink storage area 30 via the first ink groove 12A and the second ink groove 12B, the ink storage area 30 will become negative pressure if left as is, and the ink will not be able to continue to flow. Therefore, the air-liquid groove 14 performs air-liquid exchange by taking in air in an amount equivalent to the amount of ink that has flowed out, thereby preventing the ink storage area 30 from becoming negative pressure and allowing the ink in the ink storage area 30 to be continuously supplied to the writing area. The pen core 10 can be made of a resin material, and when it is formed integrally, it can be easily cleaned.

[0015] (First ink groove, second ink groove and gas-liquid groove) Next, the structures of the first ink groove 12A, the second ink groove 12B, and the gas-liquid groove 14 provided in the pen core 10 will be described with reference to Fig. 3. Fig. 3 is a schematic diagram showing an outline of the first ink groove, the second ink groove, and the gas-liquid groove. The first ink groove 12A and the second ink groove 12B extend side by side in the axial direction from their rear ends communicating with the ink storage area 30 to their front ends where they join together. The gas-liquid groove 14 extends from its rear end communicating with the ink storage area 30 toward the front end in the axial direction. As shown in Fig. 1, the rear ends of the first ink groove 12A and the second ink groove 12B coincide with the rear end of the pen core 10, but the rear end of the gas-liquid groove 14 is located slightly forward of the rear end of the pen core 10.

[0016] As shown in Figures 3(a) and 3(b), the first ink groove 12A, the second ink groove 12B, and the gas-liquid groove 14 each have a substantially rectangular cross-sectional shape. The cross section here means a cross section perpendicular to the extension direction of the groove. In Figure 3, the width and depth at the rear end of the first ink groove 12A are indicated as W1 and D1, the width and depth at the rear end of the second ink groove 12B are indicated as W2 and D2, and the width and depth at the rear end of the gas-liquid groove 14 are indicated as W3 and D3.

[0017] In this embodiment, at the rear end, the width W1 of the first ink groove 12A and the width W2 of the second ink groove 12B are the same. Meanwhile, in terms of depth, the depth D2 of the second ink groove 12B is greater (deeper) than the depth D1 of the first ink groove 12A. Therefore, at the rear end, the perimeter and cross-sectional area of ​​the second ink groove 12B are greater than the perimeter and cross-sectional area of ​​the first ink groove 12A. The width W1 and depth D1 of the first ink groove 12A and the width W2 and depth D2 of the twelfth ink groove 12B can be changed toward the front (for example, becoming narrower and shallower toward the tip). At the front end where the second ink groove 12B merges with the first ink groove 12A, the depth D2 of the second ink groove 12B is the same as the depth D1 of the first ink groove 12A.

[0018] For example, the width W1 and depth D1 of the first ink groove 12A may be substantially constant over the entire length, and the width W2 of the second ink groove 12B may be constant over the entire length, but the depth D2 may become smaller (shallower) toward the front. This allows the depth D2 of the second ink groove 12B to be the same as the depth D1 of the first ink groove 12A at the front end where the second ink groove 12B joins with the first ink groove 12A.

[0019] The first ink groove 12A extends from the rear end to the front end of the pen core 10, and there is a region in which the gas-liquid groove 14 is arranged on the upper side of the first ink groove 12A (the side where the pen tip 4 is arranged) over the length L in the groove extension direction. In this region, the first ink groove 12A and the gas-liquid groove 14 communicate with each other. In other words, the first ink groove 12A opens at the bottom of the gas-liquid groove 14 over the length L in the longitudinal direction of the groove. The front end side of the gas-liquid groove 14 with the length L communicates with the atmosphere. For example, the upper side of the gas-liquid groove 14 may be open to the atmosphere at the front end side of the gas-liquid groove 14, or the gas-liquid groove 14 may be open to the atmosphere at the side of the pen core 10, extending in a direction intersecting the axial direction away from the upper position of the first ink groove 12A.

[0020] As shown in (c) of Figure 3, if the capillary force per unit length generated on the surfaces of the first ink groove 12A, the second ink groove 12B, and the gas-liquid groove 14 is T and the angle of the capillary force T with respect to the inner surface of the groove is θ, the force per unit length drawing ink into the groove per unit length is T × cosθ. If the capillary force per unit area, which corresponds to the pressure that draws the ink in the ink storage area 30 into the first ink groove 12A, is F1, then F1 = T × cosθ × (W1 + 2 × D1) / (W1 × D1).

[0021] Similarly, if the capillary force per unit area, which corresponds to the pressure that draws the ink in the ink storage area 30 into the second ink groove 12B, is F2, then F2 = T × cosθ × (W2 + 2 × D2) / (W2 × D2). Furthermore, if the capillary force per unit area, which corresponds to the pressure with which the ink in the first ink groove 12A is drawn into the gas-liquid groove 14 through the opening at the bottom of the gas-liquid groove 14 over the length L, is denoted by F3, then: F3=T×cosθ×(2×L) / (W3×L).

[0022] In this embodiment, the capillary force F1 per unit area in the cross section of the first ink groove 12A, the capillary force F2 per unit area in the cross section of the second ink groove 12B, and the capillary force F3 per unit area at the opening of the first ink groove 12A provided at the bottom of the gas-liquid groove 14 are related to each other as follows: F1 > F2 > F3 The two parties have come to have a relationship similar to that of the two parties.

[0023] If we express this in terms of the dimensions of the grooves above, we get T×cosθ×(W1+2×D1) / (W1×D1) > =T×cosθ×(W1+2×D1) / (W1×D1) > T×cosθ×(2×L) / (W3×L) The above relationship exists. Dividing by T×cosθ gives us (W1+2×D1) / W1×D1 > (W2+2×D2) / W2×D2 >(2×L) / (W3×L) The above relationship exists.

[0024] Furthermore, if the capillary force per unit area, which corresponds to the pressure that draws the ink in the ink storage area 30 into the gas-liquid groove 14, is F4, then F4=T×cosθ ×(W3-W1+2×D3) / (W3×D3). As for F4, F1 > F2 > F4 The two parties have come to have a relationship similar to that of the two parties. In other words, (W1+2×D1) / W1×D1 > (W2+2×D2) / W2×D2 > (W3-W1+2×D3) / (W3×D3) The above relationship exists.

[0025] When comparing the cross-sectional areas of the first ink groove 12A, the second ink groove 12B, and the gas-liquid groove 14, the cross-sectional areas are basically larger in the order of the first ink groove 12A, the second ink groove 12B, and the gas-liquid groove 14. W1×D1 < W2×D2 < W3×D3 The above relationship exists. Incidentally, when the ink groove and the gas-liquid groove have a narrow and deep rectangular cross section, the perimeter becomes long, and therefore the above inequality regarding the cross-sectional area may not apply in some cases. However, even in such cases, by appropriately determining the dimensions of the ink grooves 12A, 12B and the gas-liquid groove 14, it is possible to obtain the relationship F1 > F2 > F3.

[0026] (ink, air flow) Next, the flow of ink and air in the first ink groove 12A, the second ink groove 12B, and the gas-liquid groove 14 having the above-mentioned relationship will be described with reference to Fig. 4A to Fig. 4E. Fig. 4A to Fig. 4E are diagrams that respectively show the flow of fluids in the first ink groove, the second ink groove, and the gas-liquid groove. Fig. 4A shows the state before the ink flows out of the ink storage area, Fig. 4B shows the ink starting to flow in the first ink groove, Fig. 4C shows the ink starting to flow also in the second ink groove, Fig. 4D shows the ink reaching the front end of the first ink groove, Fig. 4E shows the ink reaching the front end of the second ink groove, and Fig. 4F shows the ink flowing into the gas-liquid groove and blocking the flow of air. In each figure, (a) shows a side view along the direction in which the grooves extend, and (b) shows a cross section perpendicular to the direction in which the grooves extend. The front ends of the first ink groove 12A and the second ink groove 12B shown in FIGS. 4A to 4F indicate the positions where the two ink grooves join together.

[0027] As described above, the capillary forces F1, F2, and F3 per unit area decrease in this order: capillary force F1 per unit area drawing ink from the ink storage area 30 to the first ink groove 12A, capillary force F2 per unit area drawing ink from the ink storage area 30 to the second ink groove 12B, and capillary force F3 per unit area drawing ink from the first ink groove 12A to the gas-liquid groove 14. The capillary force F4 per unit area drawing ink from the ink storage area 30 to the gas-liquid groove 14 is also smaller than the capillary forces F1 and F2. As a result, from a state in which there is no ink in the ink grooves 12A, 12B or the gas-liquid groove 14 as shown in Figure 4A, the largest pulling force F1 causes the ink in the ink storage area 30 to flow into the first ink groove 12A and flow forward within the first ink groove 12A as shown in Figure 4B.

[0028] Following this, as shown in Fig. 4C, the next larger pulling force F2 causes the ink in the ink storage area 30 to flow into the second ink groove 12B and flow forward inside the second ink groove 12B. Air is supplied to the ink storage area 30 via the gas-liquid groove 14 by the amount of ink that has flowed into the first and second ink grooves 12A and 12B (see the dotted arrows in Figs. 4B and 4C). As shown in Fig. 4C, while the ink is flowing through the first and second ink grooves 12A and 12B, some ink may flow into the gas-liquid groove 14 from the first ink groove 12A or the ink storage area 30, but a space for air to flow is secured within the gas-liquid groove 14.

[0029] As shown in FIG. 4D, when the ink that has flowed through the first ink groove 12A reaches the front end, the direction of the ink's surface tension becomes obtuse, and the capillary force weakens. This weakens the force that draws the ink from the ink storage area 30 into the first ink groove 12A. Then, the ink in the first ink groove 12A flows into the gas-liquid groove 14 through the opening at the bottom of the gas-liquid groove 14 by a drawing force F3 that is smaller than the drawing force F1. Also, the ink in the ink storage area 30 flows into the gas-liquid groove 14 to a certain extent by a drawing force F4. As a result, the gas-liquid groove 14 is quickly filled with ink, and the air passage is closed. Since there is no other flow path that takes in air, the ink stops flowing from the ink storage area 30 into the first ink groove 12A without flowing out from the front end of the first ink groove 12A to the outside.

[0030] Meanwhile, the ink flowing in the second ink groove has not yet reached the front end, and the ink drawing force F2 is drawing ink from the ink storage area toward the front end. When ink flows into the second ink groove, the internal pressure of the ink storage tank becomes negative, and the air-liquid groove is opened to take in outside air. Then, the ink in the first ink groove starts moving again, but as shown in Figure 4E, the direction of the ink's surface tension changes and the capillary force becomes the opposite direction, and the air-liquid groove is opened only for an instant, so the ink does not flow out from the front end of the first ink groove. When the ink flowing through the second ink groove 12B reaches the front end, the direction of the ink surface tension becomes obtuse, weakening the capillary force, thereby weakening the force drawing the ink from the ink reservoir area 30 into the second ink groove.

[0031] As a result, the air-liquid groove 14 is filled with ink again, closing the air passage. Since there is no other flow path for air to enter, the ink flow stops. This keeps the first ink groove 12A, the second ink groove 12B and the air-liquid groove 14 filled with ink, preventing the ink from dripping out from the front end.

[0032] As described above, because the first ink groove 12A opens to the bottom of the gas-liquid groove 14, when the ink flowing in the second ink groove 12B reaches the front end and the flow of ink into the second ink groove 12B stops, ink immediately flows from the first ink groove 12A into the gas-liquid groove 14 through the upper opening, filling the gas-liquid groove 14 with ink. Because the first ink groove 12A is filled with ink before the ink flowing in the second ink groove 12B reaches the front end, the ink level in the first ink groove 12A has reached the bottom of the gas-liquid groove 14, and the ink in the first ink groove 12A immediately flows into the mechanism groove 14. In addition, since the first ink groove 12A has the strongest drawing force (F1) per unit area, when ink flows from inside the first ink groove 12A to the gas-liquid groove 14, the ink in the ink storage area 30 is immediately supplied to the first ink groove 12A accordingly. Therefore, the ink does not flow out from the front end, and the gas-liquid groove 14 is filled with ink.

[0033] If it is assumed that the second ink groove 12B, not the first ink groove 12A, opens to the bottom of the gas-liquid groove 14, the following occurs. Until the ink flowing in the second ink groove 12B reaches the front end, the second ink groove 12B is not completely filled with ink, and the ink level is lower than the bottom of the gas-liquid groove 14. Furthermore, since the drawing force (F2) per unit area is not as strong as that of the first ink groove (F1), when ink flows from inside the second ink groove 12B to the gas-liquid groove 14, the ink cannot be drawn from the ink storage area 30 as quickly as in the first ink groove 12A. Therefore, the gas-liquid groove 14 cannot be filled with ink as quickly as in the first ink groove 12A, and there is a risk that the ink will flow out from the front end.

[0034] As described above, when there is no ink in the ink grooves, such as when the fountain pen is first used or after cleaning, the first ink groove 12A, which has the strongest drawing force per unit area (F1), can quickly supply ink to the writing area at the front end to make the pen usable. When the ink grooves are filled with ink and the pen is usable, the second ink groove 12B, which allows a larger amount of ink to flow, can supply a sufficient amount of ink to prevent ink shortage, even for a bold pen tip. As described above, by appropriately setting the dimensions of the first ink groove 12A, the second ink groove 12B, and the gas-liquid groove 14, it is possible to prevent ink dripping.

[0035] In this way, by setting each groove so that there is a relationship F1 > F2 > F3 among the capillary force per unit area in the cross section of the first ink groove 12A, F2 per unit area in the cross section of the second ink groove 12B, and F3 per unit area at the opening of the first ink groove 12A provided at the bottom of the gas-liquid groove 14, it is possible to provide a fountain pen 2 that can quickly supply ink to the writing area from a state in which there is no ink in the ink groove and make it usable, and that can supply a sufficient amount of ink to the writing area so that the ink does not run out when in use, and that can suppress so-called ink dripping. It should be noted that F1 > F2 > F3 here is a relationship that must be satisfied from a state in which there is no ink in the first ink groove 12A and the second ink groove 12B until the ink fills the first ink groove 12A and the second ink groove 12B up to their front ends and merges.

[0036] To achieve this, the first ink groove 12A, the second ink groove 12B and the gas-liquid groove 14 each have a substantially rectangular cross-sectional shape, and if the cross-sectional width of the first ink groove 12A is W1, the cross-sectional width of the second ink groove 12B is W2, the depth is D2 and the length of the opening of the first ink groove 12A provided at the bottom of the gas-liquid groove 14 is L, then the relationship is (W1+2×D1) / W1×D1 > (W2+2×D2) / W2×D2 > (2×L) / (W3×L), thereby making the relationship (W1+2×D1) / W1×D1 > (W2+2×D2) / W2×D2 > (2×L) / (W3×L), and the above-mentioned effects can be easily and reliably achieved.

[0037] In such a first ink groove 12A and second ink groove 12B, it is preferable that the cross-sectional areas of the first ink groove 12A and the second ink groove 12B change continuously from the rear end to the front end, and that the cross-sectional areas of the first ink groove 12A and the second ink groove 12B are approximately the same at the position where they join.

[0038] As a result, at the rear end which communicates with the ink storage area 30, the first ink groove 12A, which has a strong drawing force (F1) per unit area due to capillary force, can smoothly guide ink to the writing area, and since the cross-sectional areas of the first and second ink grooves 12A, 12B are the same at the confluence, flow resistance due to differences in flow is unlikely to occur, and sufficient ink can be efficiently supplied to the writing area.

[0039] Furthermore, it is preferable that the widths W1, W2 of the first ink groove 12A and the second ink groove 12B are the same at the rear end, and the depth D2 of the second ink groove 12B is deeper than the depth D1 of the first ink groove 12A. In this case, the cross-sectional area can be adjusted by changing the depth of the first ink groove 12A and the second ink groove 12B. By arranging grooves of the same width to realize an efficient arrangement and by changing the depth of the grooves, it is possible to easily form the first ink groove 12A and the second ink groove 12B that satisfy the above condition (inequality).

[0040] The fountain pen according to the present invention is not limited to the above embodiment, and includes any other writing instrument having a hollow barrel. Although the embodiment and the mode of implementation of the present invention have been described, the disclosed contents may be changed in the details of the configuration, and the combination and order of elements in the embodiment and the mode of implementation may be changed without departing from the scope and idea of ​​the claimed invention. [Explanation of symbols]

[0041] 2 fountain pen 4. Pen Tip 10 Pen nibs 12 Ink fountain 12A First ink fountain 12B Second ink fountain 12C Merged ink groove 14 Gas-liquid groove 16 Comb groove 20 shaft cylinder 22 Neck 24 Torso axis 26 Tail plug 30 Ink storage area

Claims

1. A pen core partially covered with a nib, a barrel having an ink reservoir area therein, the barrel being fitted with the pen core at a neck portion; a first ink groove and a second ink groove, the first ink groove and the second ink groove communicating with the ink storage area at their rear ends and extending side by side in the axial direction and joining each other at their front ends; a gas-liquid groove communicating with the ink storage area at a rear end and communicating with the outside at a front end; Equipped with the first ink groove is open to a bottom of the gas-liquid groove over a predetermined length in the longitudinal direction of the groove, F1 is a capillary force per unit area in a cross section of the first ink groove, F2 is a capillary force per unit area in the cross section of the second ink groove, If the capillary force per unit area at the opening of the first ink groove provided at the bottom of the gas-liquid groove is F3, F1>F2>F3 A fountain pen characterized by having the following relationship.

2. the first ink groove, the second ink groove, and the gas-liquid groove each have a substantially rectangular cross-sectional shape, The width of the first ink groove at the rear end is W1 and the depth is D1, The width of the second ink groove at the rear end is W2 and the depth is D2, The width of the gas-liquid groove at the rear end is W3, Let L be the predetermined length of the opening of the first ink groove provided at the bottom of the gas-liquid groove. (W1+2×D1) / W1×D1 > (W2+2×D2) / W2×D2 >(2×L) / (W3×L) 2. The fountain pen according to claim 1, characterized in that:

3. 3. A fountain pen according to claim 1, characterized in that at the rear end, the widths of the first ink groove and the second ink groove are the same, and the depth of the second ink groove is deeper than the depth of the first ink groove.

4. A fountain pen as described in any one of claims 1 to 3, characterized in that the cross-sectional areas of the first ink groove and the second ink groove change continuously from the rear end to the front end, and the cross-sectional areas of the first ink groove and the second ink groove become approximately the same at the position where they join.

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