JP2025039428A - Writing implements - Google Patents

Abstract

To prevent rapid liquid leakage and to facilitate the control of liquid discharge amount by intensity of pressing by a writing instrument with a valve opened by pressing a barrel.SOLUTION: A writing instrument includes: a barrel of which an inner space is an ink storage portion storing ink, and which can be deformed by pressing a side surface; a writing tip end that is formed as a point of brush bundling fibers; a tip shaft in which the writing tip end is inserted and that is attached to the tip end of the barrel; a cylindrical brush tip holding member that is stored in the tip shaft and holds a rear end of the writing tip end in a tip end direction, a middle partition wall that divides the inside of the brush tip holding member into two parts in a fore-and-aft direction, and is formed with an insertion hole in a core; a valve mechanism that is stored in a tip end part of the barrel, is interposed between the ink storage portion and the writing tip holding member, and opens in conjunction with the pressing of the side surface of the barrel; and a porous and columnar relay core.SELECTED DRAWING: Figure 11A

Description

This disclosure relates to a writing instrument that has a valve mechanism inside the barrel and supplies ink by pressing the barrel.

Conventionally, so-called valve-type felt-tip pens, which have a valve mechanism inside the barrel, have been known to open the valve by pressing the pen tip with writing pressure (Patent Document 1) or by knocking the rear end (Patent Document 2). However, these methods have problems such as not being able to use soft pen tips such as brush tips as pen tips, and difficulty in controlling the amount of liquid dispensed.

JP 2014-87947 A Japanese Patent Application Publication No. 9-271710

In particular, the technology described in Patent Document 1 makes it possible to prevent the direct current phenomenon in which a large amount of ink unintentionally flows out, a phenomenon known as "dripping," which causes ink or coating liquid to spurt out. However, in a felt-tip pen that uses an elastic blow container for the barrel and has a mechanism for opening the valve by pressing the side of the container to allow liquid to flow out, liquid sometimes spurts out when the valve is opened. Therefore, the objective of the present disclosure is to prevent sudden liquid leakage (the phenomenon known as "dripping") in a writing instrument with a valve that opens when the barrel is pressed, and to make it easier to control the amount of liquid discharged by varying the strength of pressure.

The aspects of this disclosure are as follows:

<Aspect 1>
The writing instrument of the first aspect includes a barrel having an internal space that serves as an ink storage section for storing ink, and a barrel that is deformable when a side surface of the barrel is pressed;
A writing tip formed as a brush tip made of bundled fibers;
A tip barrel into which the writing tip is inserted and which is attached to the tip of the barrel;
A cylindrical brush tip holding member that is housed inside the tip barrel and holds the rear end of the writing tip in a tip direction;
A partition wall that divides the inside of the brush tip holding member into two in the front-rear direction and has an insertion hole formed at the axis center;
a valve mechanism that is accommodated in the tip portion of the barrel, interposed between the ink container and the brush tip holding member, and opens when a side surface of the barrel is pressed;
a cylindrical intermediate core that is inserted into the insertion hole to communicate between the valve mechanism and the writing tip and is made of a porous material;
Equipped with.

In the writing instrument of embodiment 1, the ink flows through the intermediate core. When the ink flows through the intermediate core, flow resistance is generated, which prevents the ink from dripping.

<Aspect 2>
In addition to the configuration of embodiment 1, the writing instrument of embodiment 2 has a porosity of the intermediate core of 50% or more and less than 65%. If the porosity is less than 50%, the ink may clog, making it difficult to use as a writing instrument. On the other hand, if the porosity is 65% or more, no flow resistance is generated, making it difficult to control the amount of liquid discharged. Therefore, it is preferable that the porosity of the intermediate core is 50% or more and less than 65%.

<Aspect 3>
In addition to the configuration of embodiment 2, the writing instrument of embodiment 3 has an axial length of the insertion hole of 0.5 mm or more and less than 10 mm. If the axial length is less than 0.5 mm, it becomes difficult to hold the intermediate core. On the other hand, if the axial length is 10 mm or more, the retention length becomes too long, which affects the porosity of the intermediate core and makes it difficult to control the amount of liquid discharged. Therefore, it is preferable that the axial length of the insertion hole is 0.5 mm or more and less than 10 mm.

The writing instruments of aspects 2 and 3 allow for efficient control of flow resistance.

According to an aspect of the present disclosure, a writing instrument with a valve that opens when the barrel is pressed can prevent sudden liquid outflow (so-called dripping) and make it easier to control the amount of liquid dispensed by varying the strength of pressure.

FIG. 1 is a front view of a writing instrument according to an embodiment of the present disclosure. FIG. 2 is a front view showing the writing instrument of FIG. 1 with the cap removed. FIG. 2 is a parts assembly diagram of the writing instrument of FIG. 1 . FIG. 2 is a front perspective view of the intermediate core and the brush tip holding member. FIG. 2 is a rear perspective view of the intermediate core and the brush tip holding member. FIG. 2 is a front cross-sectional view of a relay core and a brush tip holding member. FIG. 2 is a front perspective view of a brush tip holding member with a relay core attached. FIG. 2 is a rear perspective view of the brush tip holding member with the intermediate core attached. FIG. 2 is a front view of the brush tip holding member with the intermediate core attached. FIG. 2 is a plan view of the brush tip holding member with the intermediate core attached. FIG. 2 is a bottom view of the brush tip holding member with the intermediate core attached. This is a cross-sectional view taken along the line VV in FIG. 5C. FIG. FIG. FIG. FIG. FIG. 4 is a front perspective view of a spring retaining member; FIG. 4 is a rear perspective view of the spring retaining member; FIG. FIG. FIG. 4 is a bottom view of the spring retaining member. 8C is a cross-sectional view taken along line XIII-XIII of FIG. 8C. FIG. 4 is a front perspective view of the valve retaining member. FIG. 4 is a rear perspective view of the valve retaining member. FIG. FIG. FIG. FIG. 4 is a bottom view of the valve holding member. IXa-IXa cross-sectional view of FIG. 9C. IXb-IXb cross-sectional view of FIG. 9D. FIG. FIG. FIG. FIG. FIG. FIG. This is a cross-sectional view of Figure 10C along Xa-Xa. This is a cross-sectional view taken along the line Xb-Xb of Figure 10D. This is a cross-sectional view taken along the line XIa-XIa in FIG. This is a cross-sectional view of Figure 11A along the line XIb-XIb. 11B shows an enlarged view of the valve mechanism in the state shown in FIG. 11A. FIG. 2 is a front view of the writing instrument with the cap removed and the side surface of the barrel pressed. This is a cross-sectional view of Figure 13 taken along the line XIVa-XIVa. This is a cross-sectional view of Figure 14A along the line XIVb-XIVb. 14B shows an enlarged view of the valve mechanism in the state shown in FIG. 14A. FIG. 16 is a top perspective view of the valve mechanism of FIG. This is a cross-sectional view taken along the line XVIIa-XVIIa in FIG. 2. This is a cross-sectional view of Figure 17A along the line XVIIb-XVIIb. 17B shows an enlarged view of the valve mechanism alone in the state shown in FIG. 17A. FIG. 20 is a top perspective view of the valve mechanism of FIG. 18. The experimental method used to measure the flow resistance due to the material of the intermediate core is shown diagrammatically.

Embodiments of the present disclosure are described below. Note that reference numerals commonly used in multiple drawings indicate common members or parts even if no specific explanation is given for each drawing. Furthermore, the dimensions and ratios of each part shown in the drawings do not necessarily match the dimensions and ratios of the actual product. Furthermore, the dimensional relationships and ratios may differ between the drawings.

In addition, in this disclosure, the side of the writing instrument where the writing tip is located is referred to as the "tip", the direction toward the tip is referred to as the "forward" side, the opposite side is referred to as the "rear end", and the direction toward the rear end is referred to as the "publication".

Figure 1 is a front view showing the appearance of the writing instrument 10 of the present disclosure. A generally cylindrical tip barrel 12 of generally the same diameter is attached to the tip of a generally cylindrical barrel 11, and a generally cylindrical cap 13 of generally the same diameter is further attached to the tip of the tip barrel 12. Figure 2 is a front view showing the state in which the cap 13 has been removed from the state shown in Figure 1. The tip barrel 12 is composed of a generally cylindrical covering portion 12A that covers the tip of the barrel 11, an outer peripheral engaging portion 12B located on the tip side of the covering portion 12A, which is slightly reduced in diameter and has a protrusion formed on the outer periphery for engaging with the cap 13, and a tapered portion 12C at the tip of the covering portion 12A that is tapered toward the front and has an open tip. A writing tip 14 formed as a brush tip 14A made of fine bundled fibers protrudes from the opening of the tapered portion 12C.

Figure 3 is a perspective view of the parts assembly diagram of the writing instrument in Figure 1. The barrel 11 is composed of a hollow, roughly cylindrical large diameter section 11A and a small diameter section 11B formed by reducing the diameter at the tip side. The internal space of the barrel 11 is an ink storage section 11C (see Figure 11A) that stores ink. The barrel 11 is made of a relatively soft and flexible synthetic resin (such as polypropylene resin or low-density polyethylene resin), and can be deformed by pressing the side as shown in Figure 13.

The writing tip 14 is composed of a brush tip 14A formed by bundling fine fibers and a flange 14B with an expanded diameter at the rear end. As described above, the front barrel 12 is composed of a covering portion 12A, an outer peripheral locking portion 12B, and a tapered portion 12C. The writing tip 14 is inserted into the interior of the front barrel 12. As shown in Figures 11A and 11B, the internal space of the tapered portion 12C of the front barrel 12 is a front insertion hole 12D located on the front end side and having a small inner diameter, and a rear insertion hole 12E located behind it and having a larger inner diameter. The covering portion 12A of the front barrel 12 is pressed into the barrel 11 so as to cover the small diameter portion 11B of the barrel, so that the front barrel 12 is attached to the front end of the barrel 11. Furthermore, when the cap 13 is attached, the tapered portion 12C is covered, and the inner peripheral engaging portion 13A (see FIG. 11A), which is a protrusion formed on the inner surface of the cap 13, engages with the outer peripheral engaging portion 12B.

The brush tip holding member 20 is formed as a generally cylindrical member. The brush tip holding member 20 is housed inside the tip barrel 12 with the writing tip 14 inserted therethrough, and holds the rear end of the writing tip 14 in the tip direction. A cylindrical intermediate core 30 made of a porous material is inserted into the brush tip holding member 20. The intermediate core 30 is a member that connects the valve mechanism 40 and the writing tip 14.

The valve mechanism 40 is housed in the tip of the barrel 11, interposed between the ink storage section 11C (see FIG. 11A) and the brush tip holding member 20, and opens when the side of the barrel 11 is pressed (see FIG. 13). The valve mechanism 40 has a valve holding member 50 that is generally cylindrical and fixed to the barrel, a valve 60 that is inserted into the valve holding member 50 and can move in the front-rear direction, and a spring holding member 41 that is inserted inside the rear end of the valve holding member 50.

Examples of the porous material of the relay core 30 include porous bodies (sintered cores) and foams made by sintering synthetic resin powders such as polyacetal resin, polyethylene resin, acrylic resin, polyester resin, polyamide resin, polyurethane resin, polyolefin resin, polyvinyl resin, polycarbonate resin, polyether resin, polyphenylene resin, fluorine resin, and styrene resin.

Figures 4A to 4C are a front perspective view (Figure 1A), a rear perspective view (Figure 1B), and a front cross-sectional view (Figure 1C) of the intermediate core 30 and the brush tip holding member 20. The brush tip holding member 20 has a substantially cylindrical side wall 21, a partition wall 22 that divides the interior in the front-rear direction, and an insertion hole 23 formed at the axis of the partition wall 22. A ring-shaped protrusion 24 that protrudes in a ring shape is formed on the rear edge of the insertion hole 23. The inner surface of the tip side of the side wall 21 is slightly enlarged in diameter in a ring shape, and this part forms the holding step 25. The intermediate core 30 is formed of a porous body such as a fiber bundle, and is composed of a substantially cylindrical conductive part 31 in the rear part and a puncture part 32 formed with a slightly smaller diameter in the front part. The conductive part 31 is the part that is inserted into the insertion hole of the brush tip holding member 20. The puncture portion 32 is the portion that is punctured by the rear end of the writing tip 14. Here, the axial length α of the insertion hole 23 is 0.5 mm or more and less than 10 mm.

Figures 5A to 5F are a front perspective view (Figure 1A), a rear perspective view (Figure 1B), a front view (Figure 1C), a plan view (Figure 1D), a bottom view (Figure 1E), and a V-V cross-sectional view of Figure 5C of the brush tip holding member 20 to which the relay core 30 is attached. When the relay core 30 is inserted into the insertion hole 23 (see Figure 4C) of the brush tip holding member 20, the rear end of the conductive part 31 protrudes rearward from the rear end edge of the side wall 21, and the tip of the puncture part 32 protrudes forward from the tip edge of the side wall 21. In other words, the relay core 30 is held by the brush tip holding member 20 in a state where it is inserted into the insertion hole 23. Here, it is desirable that the diameter of the conductive part 31 is formed to be about 0.1 mm larger than the diameter of the insertion hole 23, so that it is slightly pressed into the insertion hole 23. In this case, it is desirable that the ratio of the axial length α (see FIG. 4C) of the insertion hole 23 to the length β (see FIG. 4C) of the relay core be 10% or more and less than 50%.

Figures 6A to 6C are a front view (Figure 6A), a plan view (Figure 6B), and a bottom view (Figure 6C) of the valve mechanism 40. As described above, the valve mechanism has a valve holding member 50, a valve 60, and a spring holding member 41. A pair of first inlet holes 55 are formed in the rear part of the valve holding member 50 (Figure 6B), through which the inserted valve 60 can be seen. The tip edge of the spring holding member 41 abuts against the tip edge of the valve holding member 50 (Figure 6A). Figure 7 is a parts assembly diagram of the valve mechanism 40. A spring 42 is interposed between the valve 60 inserted into the valve holding member 50 and the spring holding member 41, and the valve 60 is always biased backward relative to the valve holding member 50.

Figures 8A to 8F are a front perspective view (Figure 8A), a rear perspective view (Figure 8B), a front view (Figure 8C), a plan view (Figure 8D), a bottom view (Figure 8E), and a cross-sectional view (Figure 8F) of the spring holding member 41 taken along line XIII-XIII of Figure 8C. The spring holding member 41 comprises a flange-shaped bottom plate 41A, a front tubular portion 41B having a smaller diameter at its rear, an intermediate tubular portion 41C having a smaller diameter at its rear, and a rear tubular portion 41D having a smaller diameter at its rear. The step between the front tubular portion 41B and the intermediate tubular portion 41C is a liquid passage step 41E, and the step between the intermediate tubular portion 41C and the rear tubular portion 41D is a holding step 41F. The internal space of the spring holding member 41 is a flow hole 41G whose inner diameter gradually decreases toward the rear in accordance with the size of the outer diameter.

9A to 9H are a front perspective view (FIG. 9A), a rear perspective view (FIG. 9B), a front view (FIG. 9C), a side view (FIG. 9D), a plan view (FIG. 9E), a bottom view (FIG. 9F), a IXa-IXa cross-sectional view (FIG. 9G) of FIG. 9C, and a IXb-IXb cross-sectional view (FIG. 9H) of FIG. 9D of the valve holding member 50. The valve holding member 50 has a flange-shaped leading edge 51, a smaller diameter storage tube portion 52 at the rear of the flange-shaped leading edge 51, a smaller diameter liquid passage tube portion 53 at the rear of the flange-shaped leading edge 51, and a smaller diameter annular portion 54 at the rear of the flange-shaped leading edge 51. A pair of first inlet holes 55 are formed on the side of the liquid passage tube portion 53. The valve holding member 50 is formed hollow, and its internal space becomes a storage hole 56, in which the valve 60 is stored. The inner surface of the storage tube portion 52 becomes a first liquid passage surface 57. A step is formed at the leading edge of the first liquid passage surface 57, which serves as the blocking step 58. The bottom plate 41A of the spring retaining member 41 (FIGS. 8A to 8F) described above abuts against and is fixed to the leading edge of the valve retaining member 50.

Figures 10A to 10H are a front perspective view (Figure 10A), a rear perspective view (Figure 10B), a front view (Figure 10C), a side view (Figure 10D), a plan view (Figure 10E), a bottom view (Figure 10F), a Xa-Xa cross-sectional view (Figure 10G) of Figure 10C, and an Xb-Xb cross-sectional view (Figure 10H) of Figure 10D of the valve 60. The valve 60 is equipped with a cylindrical liquid passage tube 63 located at the front, an intermediate zone 64 that expands slightly in diameter behind it, a blocking slope 65 that tapers in diameter behind it, and a cylindrical vent tube 66 that is smaller in diameter than the liquid passage tube 63 behind it. The internal space of the liquid passage tube 63 is a second circulation hole 69A, and the internal space of the vent tube 66 is a vent hole 69B. Furthermore, the outer peripheral surface of the fluid passage tube 63 is the second fluid passage surface 68A, the tip edge of the fluid passage tube 63 is the fluid passage edge 68B, and the inner peripheral surface of the fluid passage tube 63 is the third fluid passage surface 68C. The intermediate tube portion 41C and the rear tube portion 41D that constitute the rear end portion of the spring retaining member 41 (FIGS. 8A to 8F) are inserted into the tip portion of the valve 60.

The valve 60 is formed by two-color molding of a rigid portion 61 made of a synthetic resin with a relatively high rigidity, and an elastic portion 62 located at the rear end and made of a synthetic resin with a higher elasticity. The elastic portion 62 is composed of a band-shaped portion 62A that covers the portion slightly forward from the rear end in a band shape, an annular portion 62B that covers the rear end in a ring shape, a pair of connecting portions 62C that connect the band-shaped portion 62A and the annular portion 62B at the side, and a diaphragm 62D that is recessed forward from the annular portion 62B. The outer peripheral surface near the rear end of the ventilation tube 66 is a covered portion 67B where the portion that comes into contact with the band-shaped portion 62A, the annular portion 62B, and the connecting portion 62C is covered by the elastic portion 62. The portion of the rigid portion 61 that is surrounded by the elastic portion 62 is an exposed portion 67A.

Figure 11A is a cross-sectional view taken along line XIa-XIa in Figure 1, and is a side cross-sectional view of the writing instrument 10. Also, Figure 11B is a cross-sectional view taken along line XIb-XIb in Figure 11A, and is a front cross-sectional view of the writing instrument 10. The assembly of the writing instrument 1 will be explained with reference to the previous figures.

First, the writing tip 14 is inserted into the front barrel 12. At this time, the brush tip 14A (see Fig. 3) of the writing tip 14 is inserted into the front insertion hole 12D (Figs. 11A and 11B) of the front barrel 12. Then, the flange 14B (Fig. 3) of the writing tip 14 abuts against the step between the front insertion hole 12D and the rear insertion hole 12E of the front barrel 12 (Figs. 11A and 11B).

Next, the brush tip holding member 20 with the intermediate core 30 inserted therethrough is inserted into the tip barrel 12. At this time, the brush tip holding member 20 is housed in the rear insertion hole 12E of the tip barrel 12. The tip of the side wall 21 (Fig. 4C) of the brush tip holding member 20 then abuts against the step (Figs. 11A, 11B) between the front insertion hole 12D and the rear insertion hole 12E of the tip barrel 12, and at the same time, the holding step 25 (Fig. 4C) at the tip edge of the side wall 21 holds the flange 14B (Fig. 3) of the writing tip 14.

Meanwhile, the valve 60 (Fig. 7) is inserted from the tip of the valve holding member 50 (Fig. 7) and the blocking slope 65 (Figs. 10D, 10G, 10H) is brought into contact with the blocking step 58 (Figs. 9G, 9H). At this time, the vent tube 66 (Fig. 10C) of the valve 60 is located inside the fluid passage tube portion 53 (Figs. 9G, 9H) of the valve holding member 50, and the fluid passage tube 63 is located in the accommodation hole 56 (Figs. 9G, 9H) of the valve holding member 50.

Then, the spring retaining member 41 (Fig. 7), with the spring 42 (Fig. 7) fitted to the rear tubular portion 41D (Figs. 8C, 8F), is inserted into the tip of the valve retaining member 50 (Fig. 7). At this time, the bottom plate 41A (Figs. 8C, 8F) of the valve retaining member 50 abuts against the tip edge 51 (Figs. 9C, 9D, 9G, 9H) of the valve retaining member 50. In this state, the spring 42 (Fig. 7) is supported between the retaining step 41F (Figs. 8C, 8F) of the spring retaining member 41 and the step between the second flow hole 69A and the air hole 69B of the valve 60 (Figs. 10G, 10H), thereby constantly biasing the valve 60 backward.

The valve 60, spring 42, and spring retaining member 41 are attached to the valve retaining member 50 to form the valve mechanism 40 (Fig. 6A). This valve mechanism 40 is inserted into the barrel 11 (Figs. 11A, 11B) with the ink storage section 11C filled with ink 11D. At this time, the storage tube section 52 (Figs. 10G, 10H) of the valve retaining member 50 is located inside the small diameter section 11B (Fig. 3) of the barrel 11, and the liquid passage tube section 53 (Figs. 10G, 10H) is located at the tip of the ink storage section 11C (Figs. 11A, 11B). Furthermore, the tip edge 51 (Figs. 9G, 9H) of the valve retaining member 50 abuts against the tip edge of the small diameter section 11B (Fig. 3) of the barrel 11 (Figs. 11A, 11B).

Then, when the covering portion 12A (Fig. 3) of the front barrel 12 is covered by the small diameter portion 11B (Fig. 3) of the barrel 11, the bottom plate 41A of the spring holding member 41 presses against the rear edge of the brush tip holding member 20 (Figs. 11A, 11B). Finally, the tapered portion 12C of the front barrel 12 is inserted from the rear end of the cap 13, and the inner peripheral locking portion (Figs. 11A, 11B) is engaged with the outer peripheral locking portion 12B (Fig. 3), completing the writing instrument 10 shown in Figs. 1, 11A, and 11B.

Figure 12 shows an enlarged view of only the valve mechanism 40 in the state shown in Figure 11. In this state, the valve 60 is biased backward by the spring 42, so that the blocking slope 65 of the valve 60 is in close contact with the blocking step 58 of the valve holding member 50. As a result, ink 11D that has entered the inside of the valve mechanism 40 from the first inlet hole 55 cannot flow between the valve holding member 50 and the valve 60, and ink 11D is not supplied to the writing tip 14. In other words, when the valve 60 is biased backward, the gap between the valve holding member 50 and the valve 60 is closed, preventing the flow of ink 11D.

Figure 13 is a front view of the writing instrument 10 with the cap 13 removed, with the side of the barrel 11 pressed. Also, Figure 14A is a cross-sectional view taken along line XIVa-XIVa in Figure 13, and Figure 14B is a cross-sectional view taken along line XIVb-XIVb in Figure 14A. As shown in these figures, when the side of the barrel 11 is pressed, the pressure inside the ink storage section 11C increases. This increased pressure presses the valve 60 forward against the biasing force of the spring 42. Figure 15 shows an enlarged view of only the valve mechanism 40 in this state. When the valve 60 is pressed forward, the blocking step 58 of the valve holding member 50 and the blocking slope 65 of the valve 60 separate, allowing the ink 11D to flow between them.

In other words, as the side of the barrel 11 is pressed, the valve 60 compresses the spring 42, opening the gap between the valve holding member 50 and the valve 60. At this time, the ink 11D flows into the valve mechanism 40 through the first inlet hole 55 that the valve holding member 50 opens to the ink storage section 11C.

As shown by the arrows in FIG. 15, the ink 11D flows between the blocking step 58 and the blocking slope 65, through the gap between the first liquid passage surface 57, which is the inner surface of the valve holding member 50, and the second liquid passage surface 68A, which is the outer surface of the valve 60, through the gap between the liquid passage edge 68B, which is the tip of the valve 60, and the spring holding member 41, and through the gap between the third liquid passage surface 68C, which is the inner surface of the valve 60, and the spring holding member 41, and then through the flow hole 41G, which is the internal space of the spring holding member 41, to reach the writing tip 14. At this time, the diaphragm 62D of the valve 60 remains recessed toward the tip, as shown in FIG. 15 and FIG. 16, which shows the state of FIG. 15 in a perspective view.

As mentioned above, even if the internal pressure of the ink storage section 11C increases, the ink 11D experiences flow resistance as it passes through the narrow liquid passage 70. In addition, the ink that reaches the flow hole 41G of the spring retaining member 41 necessarily passes through the porous intermediate core 30, and so experiences flow resistance here as well. This prevents the ink 11D from dripping from the writing tip 14.

When the pressure applied to the side of the barrel 11 is released, it returns to the state shown in FIG. 2. FIG. 17A shows the state at this time in the XVIIa-XVIIa cross section, and FIG. 17B shows the XVIIb-XVIIb cross section of FIG. 17A. When the pressure on the barrel 11 is released, the internal pressure of the ink storage section 11C drops rapidly, and air flows in from the outside due to the negative pressure by the amount of ink 11D consumed. FIG. 18 shows an enlarged view of only the valve mechanism 40 in this state. FIG. 19 shows a perspective view of this state. As shown by the arrow in FIG. 18, the diaphragm 62D of the valve 60 protrudes backward due to the pressure of the air that has passed through the circulation hole 41G and the ventilation hole 69B from the writing tip 14. At this time, air flows into the ink storage section 11C through the ventilation gap 80 generated between the rigid part 61 and the elastic part 62.

That is, the valve 60 has an elastic portion 62 at its rear end that can be elastically deformed by pressure fluctuations inside the ink storage section 11C. Then, the outside air that enters from the writing tip 14 during writing passes through the circulation hole 41G, which is the internal space of the spring holding member 41, and the ventilation hole 69B, which is the internal space of the valve 60, and reaches the ink storage section 11C through the ventilation gap 80 created by the elastic deformation of the elastic portion 62.

As described above, in the writing instrument 10 of this embodiment, the ink 11D flow path and the air replacement flow path can be separated, so smooth air replacement can be achieved even if the ink 11D flow path is narrow. In addition, it is easy to adjust the ejection condition of the ink 11D by changing the strength of the pressure on the side of the barrel 11.

Next, we verified the appropriate porosity for the material of the relay core 30. Specifically, we verified whether a porous body with the properties shown in Table 1 below would generate flow resistance for liquids. Note that the porosity shown in Table 1 below is a numerical value that represents the ratio of voids to the cross-sectional area of the porous body.

As shown in the schematic diagram of FIG. 20, for the above-mentioned Examples 1 to 4 and Comparative Example, the rear end of the barrel 11 of the writing instrument 10 shown in FIG. 11A was opened and a pressure gauge 160 and syringe 100 were attached to observe whether flow resistance occurred. As the intermediate core 30, a material having the porosity shown in Examples 1 to 4 or Comparative Example in Table 1 was used. Then, the syringe 100 was pressed in the direction of the arrow in the figure so that the ink flow rate was 10 ml/min, and the pressure gauge 160 was used to confirm whether flow resistance occurred.

As a result, the relay core 30 of the comparative example with a porosity of 67% did not generate sufficient flow resistance (pressure loss), and the pressure loss at that time was 0.1 kPa/s or less. In contrast, the relay core 30 with a porosity of 54% to 62% as in Examples 1 to 4 provided appropriate flow resistance, and the generated pressure loss was 0.5 kPa/s or more. From the above, it is inferred that the porosity of the porous body suitable for this embodiment is 50% or more and less than 65%, and that the necessary flow resistance is 0.5 kPa/s or more.

In addition, with the writing instrument disclosed herein, it is possible to adjust the flow rate by adjusting the porosity of the intermediate core and the length at which flow resistance occurs.

The present invention can be used in writing instruments that have a valve mechanism inside the barrel and supply ink by pressing the barrel.

10 Writing implement 11 Barrel 11A Large diameter portion 11B Small diameter portion 11C Ink storage portion 11D Ink 12 Tip barrel 12A Covering portion 12B Outer peripheral locking portion 12C Tapered portion 12D Front insertion hole 12E Rear insertion hole 13 Cap 13A Inner peripheral locking portion 14 Writing tip 14A Brush tip 14B Flange 20 Brush tip holding member 21 Side wall 22 Intermediate wall 23 Insertion hole 24 Annular protrusion 25 Holding step 30 Intermediate core 31 Conductive portion 32 Puncture portion 40 Valve mechanism 41 Spring holding member 41A Bottom plate 41B Front tube portion 41C Intermediate tube portion 41D Rear tube portion 41E Liquid passage step 41F Holding step 41G Flow hole 42 Spring 50 Valve retaining member 51 Tip edge 52 Storage tube portion 53 Fluid passage tube portion 54 Crowned portion 55 First inlet hole 56 Storage hole 57 First fluid passage surface 58 Blocking step 60 Valve 61 Rigid portion 62 Elastic portion 62A Belt-shaped portion 62B Annular portion 62C Connecting portion 62D Diaphragm 63 Fluid passage tube 64 Intermediate band 65 Blocking slope 66 Vent tube 67A Exposed portion 67B Covered portion 68A Second fluid passage surface 68B Fluid passage edge 68C Third fluid passage surface 69A Second flow hole 69B Vent hole 70 Fluid passage path 80 Vent gap 100 Syringe 160 Pressure gauge

Claims (3)

an ink container having an internal space for storing ink, the ink container being deformable when a side surface of the ink container is pressed;
A writing tip formed as a brush tip made of bundled fibers;
A tip barrel into which the writing tip is inserted and which is attached to the tip of the barrel;
A cylindrical brush tip holding member that is housed inside the tip barrel and holds the rear end of the writing tip in a tip direction;
A partition wall that divides the inside of the brush tip holding member into two in the front-rear direction and has an insertion hole formed at the axis center;
a valve mechanism that is accommodated in the tip portion of the barrel, interposed between the ink container and the brush tip holding member, and opens when a side surface of the barrel is pressed;
a cylindrical intermediate core that is inserted into the insertion hole to communicate between the valve mechanism and the writing tip and is made of a porous material;
A writing instrument equipped with The writing instrument according to claim 1, wherein the porosity of the intermediate core is 50% or more and less than 65%. The writing instrument according to claim 2, wherein the axial length of the insertion hole is 0.5 mm or more and less than 10 mm.