Writing instrument

Abstract

This writing instrument comprises: a barrel (11) that has an internal space serving as an ink reservoir part for containing ink and is deformable through a side surface thereof being pressed; a writing tip end (14) formed as a brush including bundled fibers; a front barrel (12) into which the writing tip end is inserted and that is attached to the tip end of the barrel; a cylindrical brush tip holding member (20) that is contained inside the front barrel and holds the rear end of the writing tip in a tip end direction; and a valve mechanism that is contained in a tip end part of the barrel, is interposed between the ink reservoir part and the brush tip holding member, and opens as the side surface of the barrel is pressed. The writing instrument allows the liquid discharge amount to be controlled by varying pressing force that is applied to the barrel.

Description

writing implements

[0001] The present disclosure relates to a writing instrument that has a valve mechanism inside a barrel and supplies ink by pressing the barrel.

[0002] 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 (Japanese Patent Laid-Open No. 2014-87947) or by knocking the rear end (Japanese Patent Laid-Open No. 9-271710).However, these methods have had issues such as not being able to use soft materials such as brush tips as the pen tip, and making it difficult to control the amount of liquid dispensed.

[0003] 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 is the spurting out of ink or coating liquid. However, in a felt-tip pen that uses a highly elastic blow-on container for the barrel and has a mechanism for opening the valve by pressing the side of the container to allow the liquid to flow out, the liquid sometimes spurts out when the valve opens. Therefore, an aspect of the present disclosure aims to prevent the sudden liquid outflow (the phenomenon known as "dripping") in a writing instrument with a valve mechanism that opens by pressing the barrel, and to make it easier to control the amount of liquid ejected by varying the strength of the pressure.

[0004] The aspects of the present disclosure are as follows.

[0005] <Aspect 1> The writing instrument of Aspect 1 comprises a barrel whose internal space is an ink storage section that stores ink and which can be deformed by pressing on the side; a writing tip formed as a brush tip made of bundled fibers; a tip barrel through which the writing tip is inserted and which is attached to the tip of the barrel; a tubular brush tip holding member that is housed inside the tip barrel and which holds the rear end of the writing tip in the tip direction; and a valve mechanism that is housed in the tip portion of the barrel and is interposed between the ink storage section and the brush tip holding member and which opens when the side of the barrel is pressed, and the amount of liquid ejected can be controlled by the strength of the pressure on the barrel.

[0006] <Aspect 2> In addition to the configuration of Aspect 1, the writing instrument of Aspect 2 comprises a partition wall that divides the interior of the brush tip holding member into two in the front-rear direction and has an insertion hole formed at the axis, and a cylindrical porous intermediate core that is inserted into the insertion hole to connect the valve mechanism and the writing tip.

[0007] In the writing implement of aspect 2, the ink flows through the intermediate core as a flow path, and flow resistance occurs when the ink passes through the intermediate core, preventing the ink from dripping.

[0008] <Aspect 3> In addition to the configuration of Aspect 2, the writing instrument of Aspect 3 has a porosity of the intermediate core of 50% or more and less than 65%. Here, if the porosity is less than 50%, there is a risk of ink clogging, making it difficult to use as a writing instrument. On the other hand, if the porosity is 65% or more, no flow resistance occurs, making it difficult to control the amount of liquid ejected. Therefore, it is preferable that the porosity of the intermediate core is 50% or more and less than 65%.

[0009] <Aspect 4> In addition to the configuration of Aspect 3, the writing instrument of Aspect 4 has an axial length of the insertion hole of 0.5 mm or more and less than 10 mm. Here, if this axial length is less than 0.5 mm, it becomes difficult to hold the lead. On the other hand, if this axial length is 10 mm or more, the holding length becomes too long, which affects the porosity of the lead and makes it difficult to control the liquid discharge amount. Therefore, it is preferable that the axial length of the insertion hole be 0.5 mm or more and less than 10 mm.

[0010] In the writing implements of Aspects 3 and 4, the flow resistance can be efficiently controlled.

[0011] <Aspect 5> A writing instrument of Aspect 4 has the same configuration as Aspect 1, and further comprises: a valve retaining member fixed to the barrel; a valve inserted into the valve retaining member and movable in the front-rear direction; a spring retaining member inserted into the rear end of the valve retaining member, with a bottom plate constituting a leading edge abutting and fixed against the leading edge of the valve retaining member and with a rear end inserted into the leading end of the valve; and a spring interposed between the spring retaining member and the valve, which constantly biases the valve rearward relative to the valve retaining member; when the valve is biased rearward, the gap between the spring retaining member and the valve is closed, thereby preventing ink from flowing; and when the valve compresses the spring in response to pressure from the side of the barrel, thereby opening the gap between the spring retaining member and the valve, the ink passes through a first inlet that the valve retaining member opens to the ink containing section, The liquid passes through a liquid passage consisting of the gap between the first liquid-passing surface, which is the inner surface of the spring retaining member, and the second liquid-passing surface, which is the outer surface of the valve, the gap between the liquid-passing edge, which is the tip of the valve, and the spring retaining member, and the gap between the third liquid-passing surface, which is the inner surface of the valve, and the spring retaining member, and then passes through the internal space of the spring retaining member to reach the writing tip.

[0012] In the writing implement of aspect 5, the ink flows through a narrow passageway, and flow resistance occurs when the ink passes through the intermediate tip, preventing the ink from dripping.

[0013] <Aspect 6> In addition to the configuration of Aspect 5, the writing instrument of Aspect 6 has an elastic portion at the rear end of the valve that is elastically deformable due to pressure fluctuations inside the ink storage section, and external air that enters from the writing tip as writing occurs passes through the internal space of the spring holding member and the air vent that is the internal space of the valve, and reaches the ink storage section through an air vent gap created by the elastic deformation of the elastic portion.

[0014] In aspect 6, by generating flow resistance of the ink in a narrow liquid passage and by differentiating the ink flow path from the air replacement flow path, it is possible to prevent so-called dripping and not hinder ink ejection. Furthermore, because the valve is a movable part, even if the ink dries and solidifies inside the valve, the ink flow path can be re-established by reopening the valve.

[0015] According to an aspect of the present disclosure, a writing instrument having a valve mechanism that opens when the barrel is pressed can prevent sudden liquid leakage (so-called dripping) and make it easier to control the amount of liquid ejected by varying the strength of the pressure.

[0016] 5C . FIG. 5C is a front view of a writing instrument according to an embodiment of the present disclosure. FIG. 5D is a front view showing the writing instrument of FIG. 1 with the cap removed. FIG. 5E is a component assembly diagram of the writing instrument of FIG. 1. FIG. 5F is a front perspective view of a relay core and a brush tip holding member. FIG. 5G is a rear perspective view of the relay core and the brush tip holding member. FIG. 5H is a front cross-sectional view of the relay core and the brush tip holding member. FIG. 5H is a front perspective view of the brush tip holding member with the relay core attached. FIG. 5H is a rear cross-sectional view of the brush tip holding member with the relay core attached. FIG. 5I is a front view of the brush tip holding member with the relay core attached. FIG. 5I is a plan view of the brush tip holding member with the relay core attached. FIG. 5I is a bottom view of the brush tip holding member with the relay core attached. FIG. 5I is a cross-sectional view taken along V-V of FIG. 5C . FIG. 5I is a front view of a valve mechanism. FIG. 5I is a plan view of the valve mechanism. FIG. 5I is a bottom view of the valve mechanism. FIG. 5I is a front perspective view of a spring holding member. FIG. 5I is a rear perspective view of the spring holding member. FIG. 5I is a front view of the spring holding member. FIG. 5I is a plan view of the spring holding member. FIG. 5I is a bottom view of the spring holding member. FIG. 5I is a cross-sectional view taken along XIII-XIII of FIG. 8C . FIG. 5I is a front perspective view of the valve holding member. 1. A rear perspective view of the valve holding member. 2. A front view of the valve holding member. 3. A side view of the valve holding member. 4. A plan view of the valve holding member. 5. A bottom view of the valve holding member. 6. A cross-sectional view taken along line IXa-IXa of FIG. 9C. 7. A cross-sectional view taken along line IXb-IXb of FIG. 9D. 8. A front perspective view of the valve. 9. A rear perspective view of the valve. 10. A side view of the valve. 11. A bottom view of the valve. 12. A cross-sectional view taken along line Xa-Xa of FIG. 10C. 13. A cross-sectional view taken along line XVIIa-XVIIa of FIG. 10D. 14. A cross-sectional view taken along line XIa-XIa of FIG. 1. 15. A cross-sectional view taken along line XVIIa-XVIIa of FIG. 2. 17A. FIG. 18 is an enlarged view of the valve mechanism in the state of FIG. 17A. FIG. 19 is a top perspective view of the valve mechanism in FIG. 20. FIG. 21 is a schematic diagram showing an experimental method used to measure the flow resistance depending on the material of the relay wick.

[0017] An embodiment of the present disclosure will be described below. Note that reference numerals commonly used in multiple drawings indicate common components or parts even if no specific explanation is given for each drawing. Furthermore, the dimensions and proportions of each part shown in the drawings do not necessarily correspond to the dimensions and proportions of the actual product. Furthermore, the dimensional relationships and proportions between the drawings may differ.

[0018] Furthermore, 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," the opposite side is referred to as the "rear end," and the direction toward the rear end is referred to as the "open end."

[0019] FIG. 1 is a front view showing the appearance of a 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. FIG. 2 is a front view showing the state shown in FIG. 1 with the cap 13 removed. 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 at the tip end, which is slightly reduced in diameter and has a ridge formed on the outer periphery for engaging with the cap 13, and a tapered portion 12C at the tip end that tapers forward and opens to the tip. A writing tip 14 formed as a brush tip 14A made of a bundle of fine fibers protrudes from the opening of the tapered portion 12C.

[0020] Figure 3 is a perspective view of the parts assembly diagram of the writing instrument of Figure 1. The barrel 11 is composed of a hollow, approximately cylindrical large-diameter section 11A and a small-diameter section 11B whose diameter is reduced toward the tip. The internal space of the barrel 11 forms 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 is deformable when the side surfaces are pressed, as shown in Figure 13.

[0021] Writing tip 14 is composed of a tapered brush tip 14A made of a bundle of fine fibers and a flange 14B with an expanded diameter at the rear end. As described above, front barrel 12 is composed of covering portion 12A, outer peripheral locking portion 12B, and tapered portion 12C. Writing tip 14 is inserted into the interior of front barrel 12. As shown in FIGS. 11A and 11B , the internal space of tapered portion 12C of front barrel 12 forms a front insertion hole 12D with a small inner diameter located toward the front end, and a rear insertion hole 12E with a larger inner diameter located behind it. Front barrel 12 is attached to the front end of barrel 11 by press-fitting covering portion 12A of front barrel 12 into small-diameter portion 11B of the barrel. When the cap 13 is attached, the tapered portion 12C is covered, and an inner peripheral locking portion 13A (see FIG. 11A), which is a protrusion formed on the inner surface of the cap 13, locks with the outer peripheral locking portion 12B.

[0022] The brush tip holding member 20 is formed as a substantially 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 forward direction. A cylindrical porous intermediate core 30 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.

[0023] 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 is a member that opens when the side of the barrel 11 is pressed (see FIG. 13). The valve mechanism 40 has a substantially cylindrical valve holding member 50 that is fixed to the barrel, a valve 60 that is inserted into the valve holding member 50 and is movable in the front-to-rear direction, and a spring holding member 41 that is inserted inside the rear end of the valve holding member 50.

[0024] 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.

[0025] 4A to 4C are a front perspective view (FIG. 1A), a rear perspective view (FIG. 1B), and a front cross-sectional view (FIG. 1C) of the intermediate core 30 and the brush tip holding member 20. The brush tip holding member 20 includes a substantially cylindrical side wall 21, a partition wall 22 that divides the interior in two in the front-rear direction, and an insertion hole 23 formed at the axis of the partition wall 22. A ring-shaped protrusion 24 protrudes from the rear edge of the insertion hole 23. The inner surface of the tip end of the side wall 21 is slightly enlarged in diameter, forming a holding step 25. The intermediate core 30 is formed of a porous material such as a fiber bundle and is composed of a substantially cylindrical conductive portion 31 at the rear and a slightly smaller-diameter puncture portion 32 at the front. The conductive portion 31 is inserted into the insertion hole of the brush tip holding member 20. Puncture portion 32 is a portion that is punctured by the rear end of writing tip 14. Here, axial length α of insertion hole 23 is 0.5 mm or more and less than 10 mm.

[0026] 5A to 5F show a front perspective view (FIG. 1A), a rear perspective view (FIG. 1B), a front view (FIG. 1C), a plan view (FIG. 1D), a bottom view (FIG. 1E), and a V-V cross-sectional view of FIG. 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 FIG. 4C) of the brush tip holding member 20, the rear end of the conductive portion 31 protrudes rearward beyond the rear edge of the side wall 21, and the tip of the puncturing portion 32 protrudes forward beyond the tip edge of the side wall 21. In other words, the relay core 30 is held by the brush tip holding member 20 while inserted into the insertion hole 23. Here, it is desirable that the diameter of the conductive portion 31 be formed approximately 0.1 mm larger than the diameter of the insertion hole 23, so that it is slightly press-fit 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%.

[0027] 6A to 6C are a front view (FIG. 6A), a plan view (FIG. 6B), and a bottom view (FIG. 6C) of the valve mechanism 40. As described above, the valve mechanism includes a valve retaining member 50, a valve 60, and a spring retaining member 41. A pair of first inlet holes 55 are formed in the rear portion of the valve retaining member 50 (FIG. 6B), through which the inserted valve 60 can be seen. The leading edge of the spring retaining member 41 abuts against the leading edge of the valve retaining member 50 (FIG. 6A). FIG. 7 is a component assembly diagram of the valve mechanism 40. A spring 42 is interposed between the valve 60 inserted into the valve retaining member 50 and the spring retaining member 41, constantly biasing the valve 60 rearward relative to the valve retaining member 50.

[0028] 8A to 8F are a front perspective view (FIG. 8A), a rear perspective view (FIG. 8B), a front view (FIG. 8C), a plan view (FIG. 8D), a bottom view (FIG. 8E), and a cross-sectional view (FIG. 8F) of the spring retainer 41 taken along line XIII-XIII of FIG. 8C. The spring retainer 41 includes 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 fluid passage step 41E, and the step between the intermediate tubular portion 41C and the rear tubular portion 41D is a retention step 41F. The internal space of the spring retainer 41 is a flow hole 41G whose inner diameter gradually decreases rearward to match the outer diameter.

[0029] 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 retaining member 50. The valve retaining member 50 includes a flange-shaped leading edge 51, a smaller-diameter accommodating tubular portion 52 at its rear, a smaller-diameter fluid-passing tubular portion 53 at its rear, and a smaller-diameter annular portion 54 at its rear. A pair of first inlet holes 55 are formed in the side surface of the fluid-passing tubular portion 53. The valve retaining member 50 is hollow, and its internal space forms an accommodating hole 56 in which a valve 60 is accommodated. The inner surface of the accommodating tubular portion 52 forms a first fluid-passing surface 57. A step is formed on the leading edge of the first fluid passage surface 57, and this step serves as a blocking step 58. The bottom plate 41A of the spring holding member 41 (FIGS. 8A to 8F) described above abuts against the leading edge of the valve holding member 50 and is fixed thereto.

[0030] 10A to 10H are a front perspective view (FIG. 10A), a rear perspective view (FIG. 10B), a front view (FIG. 10C), a side view (FIG. 10D), a plan view (FIG. 10E), a bottom view (FIG. 10F), a cross-sectional view Xa-Xa of FIG. 10C (FIG. 10G), and a cross-sectional view Xb-Xb of FIG. 10D (FIG. 10H) of the valve 60. The valve 60 includes a cylindrical liquid passage tube 63 located at the front, an intermediate band 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 and located behind it. The internal space of the liquid passage tube 63 is a second flow 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 a second fluid passage surface 68A, the tip edge of the fluid passage tube 63 is a fluid passage edge 68B, and the inner peripheral surface of the fluid passage tube 63 is a third fluid passage surface 68C. The intermediate tubular portion 41C and the rear tubular portion 41D that form the rear end portion of the spring holding member 41 (FIGS. 8A to 8F) are inserted into the tip portion of the valve 60.

[0031] The valve 60 is formed by two-color molding with a rigid portion 61 made of a relatively rigid synthetic resin and an elastic portion 62 located at the rear end and made of a more elastic synthetic resin. The elastic portion 62 is composed of a band-shaped portion 62A that covers the portion slightly forward of the rear end, 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 sides, and a diaphragm 62D that is recessed forward from the annular portion 62B. The outer peripheral surface of the vent tube 66 near the rear end, which abuts the band-shaped portion 62A, the annular portion 62B, and the connecting portion 62C, is covered by the elastic portion 62 to form a covered portion 67B. The portion of the rigid portion 61 surrounded by the elastic portion 62 is an exposed portion 67A.

[0032] 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. 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 described with reference to the previous figures.

[0033] First, writing tip 14 is inserted into front barrel 12. At this time, brush tip 14A (see FIG. 3) of writing tip 14 is inserted into front insertion hole 12D (FIGS. 11A and 11B) of front barrel 12. Then, flange 14B (FIG. 3) of writing tip 14 abuts against the step between front insertion hole 12D and rear insertion hole 12E of front barrel 12 (FIGS. 11A and 11B).

[0034] Next, brush tip holding member 20 with relay core 30 inserted therethrough is inserted into tip barrel 12. At this time, brush tip holding member 20 is housed in rear insertion hole 12E of tip barrel 12. The tip of side wall 21 (FIG. 4C) of brush tip holding member 20 then abuts against the step (FIGS. 11A and 11B) between front insertion hole 12D and rear insertion hole 12E of tip barrel 12, and at the same time, holding step 25 (FIG. 4C) on the tip edge of side wall 21 holds flange 14B (FIG. 3) of writing tip 14.

[0035] Meanwhile, the valve 60 (FIG. 7) is inserted from the tip of the valve holding member 50 (FIG. 7) so that the blocking slope 65 (FIGS. 10D, 10G, 10H) abuts against 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.

[0036] Then, the spring retaining member 41 (FIG. 7), with the spring 42 (FIG. 7) fitted around the rear tubular portion 41D (FIGS. 8C and 8F), is inserted into the valve retaining member 50 (FIG. 7) from the front end. At this time, the bottom plate 41A (FIGS. 8C and 8F) of the valve retaining member 50 abuts against the front edge 51 (FIGS. 9C, 9D, 9G, and 9H) of the valve retaining member 50. In this state, the spring 42 (FIG. 7) is supported between the retaining step 41F (FIGS. 8C and 8F) of the spring retaining member 41 and the step (FIGS. 10G and 10H) between the second flow hole 69A and the vent hole 69B of the valve 60, thereby constantly biasing the valve 60 rearward.

[0037] The valve mechanism 40 (FIG. 6A) is formed by attaching the valve 60, spring 42, and spring holder 41 to the valve holder 50. This valve mechanism 40 is inserted into the barrel 11 (FIGS. 11A and 11B) with the ink storage section 11C filled with ink 11D. At this time, the storage tube portion 52 (FIGS. 10G and 10H) of the valve holder 50 is positioned inside the small-diameter portion 11B (FIG. 3) of the barrel 11, and the fluid-passing tube portion 53 (FIGS. 10G and 10H) is positioned at the tip of the ink storage section 11C (FIGS. 11A and 11B). Furthermore, the leading edge 51 (FIGS. 9G and 9H) of the valve holder 50 abuts against the leading edge of the small-diameter portion 11B (FIG. 3) of the barrel 11 (FIGS. 11A and 11B).

[0038] Then, when covering portion 12A (Fig. 3) of front barrel 12 is fitted over small diameter portion 11B (Fig. 3) of barrel tube 11, bottom plate 41A of spring retaining member 41 presses against the rear edge of brush tip retaining member 20 (Figs. 11A and 11B). Finally, tapered portion 12C of front barrel 12 is inserted from the rear end of cap 13, and inner peripheral locking portion 12B (Fig. 3) is engaged with inner peripheral locking portion (Figs. 11A and 11B), completing writing instrument 10 shown in Figs. 1, 11A, and 11B.

[0039] Figure 12 is 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, causing the blocking slope 65 of the valve 60 to come into close contact with the blocking step 58 of the valve holding member 50. As a result, ink 11D that has entered 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.

[0040] FIG. 13 is a front view of the writing instrument 10 with the cap 13 removed, showing the state in which the side of the barrel 11 is pressed. FIG. 14A is a cross-sectional view taken along line XIVa-XIVa of FIG. 13, and FIG. 14B is a cross-sectional view taken along line XIVb-XIVb of FIG. 14A. As shown in these figures, when the side of the barrel 11 is pressed, the pressure inside the ink storage compartment 11C increases. This increased pressure presses the valve 60 forward against the biasing force of the spring 42. FIG. 15 is an enlarged view of the valve mechanism 40 in this state. Pressing the valve 60 forward separates the shutoff step 58 of the valve retaining member 50 from the shutoff slope 65 of the valve 60, allowing ink 11D to flow between them.

[0041] That is, as the side surface of the barrel 11 is pressed, the valve 60 compresses the spring 42, thereby 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 55 that the valve holding member 50 opens to the ink containing section 11C.

[0042] 15, the ink 11D that has flowed in passes between the blocking step 58 and the blocking slope 65, then passes through a liquid passage 70 that is made up of 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, the gap between the liquid passage edge 68B, which is the tip of the valve 60, and the spring holding member 41, and the gap between the third liquid passage surface 68C, which is the inner surface of the valve 60, and the spring holding member 41, before passing through the communication 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 is a perspective view of the state shown in FIG. 15.

[0043] As described 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. Furthermore, the ink that reaches the flow hole 41G of the spring retaining member 41 must pass through the porous relay core 30, and so experiences flow resistance there as well. This prevents the ink 11D from dripping from the writing tip 14.

[0044] When the pressure applied to the side of the barrel 11 is released, the pen returns to the state shown in Figure 2. Figure 17A shows this state in the XVIIa-XVIIa cross section, and Figure 17B shows it in the XVIIb-XVIIb cross section of Figure 17A. When the pressure on the barrel 11 is released, the internal pressure of the ink storage compartment 11C rapidly decreases, and the negative pressure causes air to flow in from the outside in an amount equal to the amount of ink 11D consumed. Figure 18 shows an enlarged view of the valve mechanism 40 in this state. Figure 19 also shows a perspective view of this state. As indicated by the arrow in Figure 18, the diaphragm 62D of the valve 60 protrudes rearward due to the pressure of air flowing from the writing tip 14 through the flow hole 41G and the air vent 69B. At this time, air flows into the ink storage compartment 11C through the air gap 80 created between the rigid portion 61 and the elastic portion 62.

[0045] That is, the valve 60 has an elastic portion 62 at its rear end that is elastically deformable due to pressure fluctuations inside the ink containing portion 11C. 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 then reaches the ink containing portion 11C through the ventilation gap 80 created by the elastic deformation of the elastic portion 62.

[0046] 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, the ejection condition of the ink 11D can be easily adjusted by the strength of the pressure on the side of the barrel 11.

[0047] Next, the porosity suitable for the material of the relay core 30 was examined. Specifically, it was examined whether or not a flow resistance to a liquid occurs in a porous body having the properties shown in Table 1 below. The porosity shown in Table 1 below is a numerical value expressed as the ratio of voids to the cross-sectional area of ​​the porous body.

[0048]

[0049] 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 Figure 11A was opened, and a pressure meter 160 and syringe 100 were attached, and the presence or absence of flow resistance was observed, as shown in the schematic diagram in Figure 20. A material having the porosity shown in Examples 1 to 4 or Comparative Example in Table 1 was used as the relay core 30. 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 presence or absence of flow resistance was confirmed using the pressure meter 160.

[0050] As a result, the relay wick 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 wicks 30 with porosities of 54% to 62% as in Examples 1 to 4 obtained 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 but less than 65%, and that the required flow resistance is 0.5 kPa / s or more.

[0051] Furthermore, in the writing instrument of the present disclosure, it is also possible to adjust the flow rate by adjusting the porosity of the intermediate core or the length at which flow resistance occurs.

[0052] In light of the above, preferred embodiments of the writing instrument of the present disclosure are as follows.

[0053] The writing instrument 10 of the first embodiment comprises a barrel 11 whose internal space is an ink storage section 11C that stores ink 11D and which can be deformed by pressing on its side surface; a writing tip 14 formed as a brush tip made of bundled fibers; a front barrel 12 through which the writing tip 14 is inserted and which is attached to the front end of the barrel 11; a cylindrical brush tip holding member 20 that is housed inside the front barrel 12 and holds the rear end of the writing tip 14 in the tip direction; and a valve mechanism 40 that is housed in the front portion of the barrel 11 and is interposed between the ink storage section 11C and the brush tip holding member 20 and opens when the side surface of the barrel 11 is pressed, and the amount of liquid ejected can be controlled by the strength of the pressure on the barrel 11.

[0054] The writing instrument 10 of the second embodiment has, in addition to the configuration of the first embodiment, a partition wall 22 that divides the interior of the brush tip holding member 20 into two in the front-to-rear direction and has an insertion hole 23 formed at the axis, and a cylindrical porous relay core 30 that is inserted into the insertion hole 23 to connect the valve mechanism 40 and the writing tip 14.

[0055] In addition to the configuration of the second embodiment, the writing instrument 10 of the third embodiment has a porosity of the relay core 30 of 50% or more and less than 65%.

[0056] In the writing implement 10 of the fourth embodiment, in addition to the configuration of the third embodiment, the axial length of the insertion hole 23 is 0.5 mm or more and less than 10 mm.

[0057] In a fifth aspect of the writing instrument 10, in addition to the configuration of the first aspect, the valve mechanism 40 comprises: a valve retaining member 50 fixed to the barrel 11; a valve 60 inserted into the valve retaining member 50 and movable in the front-to-rear direction; a spring retaining member 41 inserted inside the rear end of the valve retaining member 50, with a bottom plate 41A constituting the leading edge abutting and fixed against the leading edge of the valve retaining member 50, and with a rear end portion inserted into the leading end portion of the valve 60; and a spring 42 interposed between the spring retaining member 41 and the valve 60, and constantly urging the valve 60 rearward relative to the valve retaining member 50. When the valve 60 is urged rearward, the gap between the spring retaining member 41 and the valve 60 is closed, thereby preventing the flow of ink 11D. When the valve 60 is urged rearward, the valve 60 compresses the spring 42 in response to pressure against the side of the barrel 11, thereby opening the gap between the spring retaining member 41 and the valve 60, The ink 11D passes through a first inlet 55 that the valve holding member 50 opens to the ink storage section 11C, passes through a liquid passage 70 that is made up of the gap between a first liquid passage surface 57 that is the inner surface of the spring holding member 41 and a second liquid passage surface 68A that is the outer surface of the valve 60, the gap between a liquid passage edge 68B that is the tip of the valve 60 and the spring holding member 41, and the gap between a third liquid passage surface 68C that is the inner surface of the valve 60 and the spring holding member 41, and then passes through the internal space of the spring holding member 41 to reach the writing tip 14.

[0058] In the sixth embodiment of the writing instrument 10, in addition to the configuration of the fifth embodiment, the valve 60 is provided at its rear end with an elastic portion 62 that is elastically deformable due to pressure fluctuations inside the ink storage section 11C, and external air that enters from the writing tip 14 during writing passes through the internal space of the spring retaining member 41 and the internal space of the valve 60, i.e., an air vent 69B, and reaches the ink storage section 11C through an air gap 80 created by the elastic deformation of the elastic portion 62.

[0059] The present invention can be used in a writing instrument that has a valve mechanism inside the barrel and supplies ink by pressing the barrel.

Claims

1. A writing instrument comprising: a barrel whose internal space is an ink storage section for storing ink and which can be deformed when the side of the barrel is pressed; a writing tip formed as a brush tip made of bundled fibers; a tip barrel through which the writing tip is inserted and which is attached to the tip of the barrel; a cylindrical tip holding member housed inside the tip barrel and which holds the rear end of the writing tip in the tip direction; a valve mechanism housed in the tip portion of the barrel and interposed between the ink storage section and the tip holding member, which opens when the side of the barrel is pressed; and the amount of liquid discharged can be controlled by the strength of pressure applied to the barrel.

2. The writing instrument as described in claim 1, comprising: a partition wall that divides the inside of the brush tip holding member in the front-rear direction and has an insertion hole formed at its axis; and a cylindrical porous intermediate core that is inserted into the insertion hole to connect the valve mechanism and the writing tip.

3. The writing instrument according to claim 2, wherein the porosity of the intermediate core is 50% or more and less than 65%.

4. The writing implement according to claim 3, wherein the axial length of the insertion hole is equal to or greater than 0.5 mm and less than 10 mm.

5. The valve mechanism comprises: a valve retaining member fixed to the barrel; a valve inserted into the valve retaining member and movable in the front-rear direction; a spring retaining member inserted inside the rear end of the valve retaining member, with a bottom plate constituting a leading edge abutting and fixed to the leading edge of the valve retaining member and a rear end portion inserted into the leading end portion of the valve; and a spring interposed between the spring retaining member and the valve, which constantly urges the valve rearward relative to the valve retaining member; when the valve is urged rearward, the gap between the spring retaining member and the valve is closed to prevent ink flow; and when the valve compresses the spring in response to pressure from the side of the barrel, thereby opening the gap between the spring retaining member and the valve, the ink passes through a first inlet hole that the valve retaining member opens to the ink storage section, 2. The writing instrument of claim 1, wherein the liquid passes through a liquid passage consisting of a gap between a first liquid passing surface which is the inner surface of the spring retaining member and a second liquid passing surface which is the outer surface of the valve, a gap between a liquid passing edge which is the tip of the valve and the spring retaining member, and a gap between a third liquid passing surface which is the inner surface of the valve and the spring retaining member, and then passes through an internal space of the spring retaining member to reach the writing tip.

6. A writing instrument as described in claim 5, wherein the valve is provided at its rear end with an elastic portion which is elastically deformable in response to pressure fluctuations within the ink storage portion, and external air which enters from the writing tip as writing progresses passes through an air vent which is the internal space of the spring retaining member and the internal space of the valve, and reaches the ink storage portion through an air vent gap which is generated by the elastic deformation of the elastic portion.

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