Notepads

Abstract

To provide a writing implement that can freely change the width of a drawn line depending on writing pressure and that can be used with a thin-shaft felt-tip pen or marking pen. [Solution] The writing instrument 1 comprises a barrel 10, an ink supply core 20 housed inside the barrel 10 and guiding ink by capillary force, and a core surrounding member 30 attached to the tip of the barrel 10, through which the ink supply core 20 passes and from which the tip of the ink supply core 20 protrudes, the ink supply core 20 moves rearward at the tip of the core surrounding member 30 due to writing pressure, and the protrusion dimension of the ink supply core from the tip of the core surrounding member 30 is 0.05 to 0.7 mm.

Description

[Technical Field]

[0001] The present invention relates to a writing implement that allows the width of a drawn line to be changed when writing. [Background technology]

[0002] Patent document 1 describes a writing instrument comprising a barrel, an ink supply core housed inside the barrel and capable of guiding ink by capillary force, and a core surrounding member that covers the outer periphery of the ink supply core, with the ink supply core and a portion of the core surrounding member exposed from the tip of the barrel, the writing instrument also comprising a displacement means that can relatively change the axial positional relationship between the ink supply core and the core surrounding member, and the displacement means is used to move the ink supply core backward relative to the core surrounding member, thereby allowing the tip of the ink supply core and the tip of the core surrounding member to simultaneously come into contact with the writing surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-026930 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a writing instrument that allows the width of a drawn line to be freely changed by the writing pressure and that is compatible with thin-barreled felt-tip pens or marking pens. [Means for solving the problem]

[0005] A writing instrument according to a first aspect of the present invention comprises a barrel; an ink supply core housed inside the barrel and guiding ink by capillary force; a core surrounding member that is attached to the tip of the barrel, through which the ink supply core passes and from which the tip of the ink supply core protrudes, The ink supply core moves rearward at the tip of the core surrounding member due to writing pressure, The protrusion dimension of the ink supply core from the tip of the core surrounding member is 0.05 to 0.7 mm when not writing.

[0006] A writing instrument according to a second aspect of the present invention has the same features as the writing instrument according to the first aspect, in addition to the above, wherein the ink supply wick has a flow path therein that guides ink by capillary force; the ink supply core surrounding member has a tip opening through which the tip of the ink supply core protrudes, The value obtained by subtracting the outer diameter of the flow path from the inner diameter of the tip opening is 0.5 mm or less. It should be noted that the numerical value can be a negative number.

[0007] A writing instrument according to a third aspect of the present invention is characterized in that, in addition to the characteristics of the writing instrument according to the second aspect, the value obtained by subtracting the outer diameter of the flow path from the inner diameter of the tip opening is less than 0.

[0008] A writing instrument according to a fourth aspect of the present invention has the features of the writing instrument according to any one of the first to third aspects, in addition to which the lead surrounding member has a front end portion, a rear end portion, and an elastic portion sandwiched between the front end portion and the rear end portion; The elastic portion allows the ink supply core to move rearward together with the rear end portion.

[0009] A writing instrument according to a fifth aspect of the present invention has the same features as the writing instrument according to the fourth aspect, but is also characterized in that the elastic portion is integral with the tip portion.

[0010] A writing instrument according to a sixth aspect of the present invention has the same features as the writing instrument according to the fourth aspect, but is also characterized in that the elastic portion is separate from the tip portion.

[0011] A writing instrument according to a seventh aspect of the present invention has the same characteristics as the writing instrument according to any one of the fourth to sixth aspects, and is characterized in that the elastic portion extends rearward due to writing pressure.

[0012] The writing instrument according to the eighth aspect of the present invention has the same characteristics as the writing instrument according to any one of the fourth to seventh aspects, and is characterized in that the ink supply core and the core surrounding member are fixed to each other.

[0013] A writing instrument according to a ninth aspect of the present invention is characterized in that, in addition to the characteristics of the writing instrument according to the eighth aspect, the fixation is due to impact deformation of the outer surface of the rear end of the lead surrounding member. [Effects of the Invention]

[0014] Since each aspect of the present invention is configured as described above, it is possible to freely change the width of the drawn line by changing the writing pressure even when using a thin-shaft felt-tip pen or marking pen. [Brief explanation of the drawings]

[0015] [Figure 1A] 1 is a front view showing the overall configuration of a writing instrument according to an embodiment of the present invention. [Figure 1B] FIG. 1B is a cross-sectional view of FIG. 1A taken along line α-α. [Figure 2] This is an enlarged view of the main part of Figure 1B. [Figure 3A] FIG. 2 is a perspective view showing a grip member of the writing instrument according to the present embodiment. [Figure 3B] FIG. 2 is a side view showing a grip member of the writing instrument according to the present embodiment. [Figure 3C] FIG. 3C is a β-β cross-sectional view of FIG. 3B. [Figure 4A] FIG. 2 is a perspective view showing a cap of the writing instrument according to the present embodiment. [Figure 4B] 4B is a cross-sectional view of FIG. 4A taken along line γ-γ. [Figure 4C] FIG. 4B is a cross-sectional view of FIG. 4A taken along line δ-δ. [Figure 5A] FIG. 2 is a plan view showing the head of the cap in the writing instrument according to the embodiment. [Figure 5B] 10B is a bottom view showing the insertion portion of the cap in the writing instrument according to the present embodiment. FIG. [Figure 5C] 1 is a side cross-sectional view showing the state when the tip barrel is inserted into the cap in the writing instrument according to the present embodiment. FIG. [Figure 6A] FIG. 2 is a perspective view showing the tail plug of the writing instrument according to the present embodiment. [Figure 6B] FIG. 2 is a side view showing the tail plug of the writing instrument according to the present embodiment. [Figure 6C] FIG. 6C is a cross-sectional view of FIG. 6B along ε-ε. [Figure 7A] FIG. 2 is a perspective view of a lead surrounding member in the writing instrument according to the present embodiment. [Figure 7B] FIG. 2 is a side view of the lead surrounding member in the writing instrument according to the embodiment. [Figure 7C] FIG. 7C is a cross-sectional view of FIG. 7B taken along line ζ-ζ. [Figure 8A] 10 is a side view showing a modified example of the lead surrounding member in the writing instrument according to the present embodiment. FIG. [Figure 8B] FIG. 8B is a cross-sectional view taken along the line η-η of FIG. 8A. [Figure 9A] 1 is a cross-sectional view showing the ink supply core and the core surrounding member in the writing instrument according to the embodiment in a state before operation. FIG. [Figure 9B] 1 is a cross-sectional view showing the ink supply core and the core surrounding member in operation in the writing instrument according to the embodiment. FIG. [Figure 10A] FIG. 2 is an enlarged cross-sectional view showing the tip of the writing implement according to the present embodiment. [Figure 10B] 10B is a θ-θ cross-sectional view showing an example of the ink supply core of FIG. 10A. FIG [Figure 10C] Another example of the ink supply core of FIG. 10A is shown in a cross-sectional view similar to FIG. 10B. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, with reference to the drawings, a thin-barreled felt-tip pen or marking pen will be described as an example of the writing instrument 1 according to this embodiment. Note that in each drawing, the "front" of the writing instrument 1 and its components refers to the direction toward the tip of the writing instrument 1, the "rear" refers to the opposite direction, the "axial direction" refers to the direction of the axis that runs from the front to the rear of the barrel 10, and the "transverse direction" refers to the direction perpendicular to the axial direction. Furthermore, symbols commonly used in each drawing represent the same configuration or component, even if not specifically mentioned in the description of each drawing.

[0017] <Overall structure> As shown in Fig. 1A, writing instrument 1 according to this embodiment comprises barrel 10 in which smaller-diameter front barrel 11 and larger-diameter rear barrel 12 are integrally formed (see Fig. 2), and lead surrounding member 30 attached to the front side of front barrel 11. As shown in Fig. 1B, inside rear barrel 12, a padding 15 in which ink is stored is housed. An air replacement port 11E is provided near the tip of front barrel 11, allowing air to pass between the inside and outside of barrel 10. The ink supply core 20 penetrates the core surrounding member 30. The tip of the ink supply core 20 protrudes from the tip of the core surrounding member 30. The rear end of the ink supply core 20 extends until it pierces the front end of the padding 15. Although not shown in FIG. 1A, cap 50 shown in FIGS. 4A to 4C is attached to front barrel 11 shown in FIG. 1A.

[0018] (Structure of the barrel) 1B, barrel 10, as described above, has front barrel 11 and rear barrel 12. Front opening 13 opens at the front end of front barrel 11, and rear opening 14 opens at the rear end of rear barrel 12. A tail plug 60 is press-fitted into rear opening 14. As shown in FIG. 3A, the outer shape of the barrel 10 is formed such that the cross section in the transverse direction is a generally rounded rectangle.

[0019] As shown in FIG. 2, the rear body 12 is integrally formed with a front grip portion 12A on the front side covered with a grip member 40 described later, and a rear grip portion 12B on the rear side. Furthermore, the front grip portion 12A and the rear grip portion 12B have a step at their boundary 12C that narrows in diameter toward the front, making the front grip portion 12A thinner than the rear grip portion 12B. A plurality of axially elongated rectangular slots 12D are formed in part of the outer circumferential surface of the front grip portion 12A. Locking pieces 44 projecting from the inner surface of the grip member 40 (described later) fit into these slots 12D. Furthermore, front end 12E of front grip 12A is formed with a surface whose cross section in the transverse direction is a convex arc, and front barrel 11 formed integrally in front of it is thinner than this end 12E. Furthermore, a flange 62 of a tail plug 60 contacts the rear end edge of the rear body 12 (see FIG. 1B).

[0020] As shown in FIG. 2, front barrel 11 has, from the rear end, base portion 11A, reduced diameter portion 11B, tip portion 11C, and locking surface 11D. The base portion 11A is a portion that extends forward with a constant thickness from the front end portion 12E of the front grip portion 12A. As shown in Fig. 2 and Figs. 3A-C, protrusions are formed on each side of the middle portion of the base portion 11A along a direction that intersects with the axial direction. These protrusions are referred to as locking protrusions 11A1. In this embodiment, a total of four locking protrusions 11A1 are provided. The reduced diameter portion 11B is a portion that tapers and extends forward from the front end of the base portion 11A. The tip portion 11C is a portion that extends forward with a constant thickness from the front end of the reduced diameter portion 11B. The locking surface 11D is the tip edge of the tip portion 11C, and is in contact with an engaging piece 33A of an engaging portion 33 of the lead surrounding member 30, which will be described later.

[0021] (gripping member) As shown in FIGS. 3A to 3C, the gripping member 40 is formed in a cylindrical shape with a substantially square cross section as a whole, and has a front opening 42 that opens to the front and a rear opening 43 that opens to the rear. Multiple locking pieces 44 protrude inward from the inside of the gripping member 40 and are formed as long axial ridges. These locking pieces 44 fit into multiple slots 12D provided on the outer periphery of the front gripping portion 12A of the rear axle 12, thereby attaching the gripping member 40 to the rear axle 12. Edge 42A is formed at the end of front opening 42. The inner surface of edge 42A is formed with a concave arc-shaped cross section that corresponds to the convex arc-shaped cross section of end 12E of front grip 12A. Front opening 42 is formed with a size that allows root portion 11A of front barrel 11 to fit inside. An end face 43A is formed at the end of the rear opening 43, and is in contact with the stepped surface of the boundary portion 12C of the rear grip portion 12B of the rear body 12. Furthermore, as shown in Figures 3A and 3B, the gripping member 40 may be given a color different from that of the barrel 10, and the color may be similar to the color of the ink stored in the padding 15, for example. The barrel 10 and the gripping member 40 can be formed by two-color molding, for example.

[0022] (cap) As shown in FIGS. 4A to 4C and 5A to 5C, the cap 50 has a cap outer cylinder 51 and a cap inner cylinder 52.

[0023] 4A, the cap outer cylinder 51 is formed in a cylindrical shape as a whole, and has openings at the front and rear. Of these, the rear opening is referred to as a rear opening 54. The outer peripheral surface of this cap outer cylinder 51 has a cross section in the transverse direction that is formed into a generally rounded quadrangle, similar to the outer peripheral surface of the barrel 10. As shown in Figures 4A-C and 5A-C, the cap inner tube 52 is formed in a cylindrical shape with a closed front end and an open rear end. The cap inner tube 52 is housed in the front half of the interior of the cap outer tube 51, and its open rear end is connected to the inner circumferential surface of the cap outer tube 51 at approximately the middle portion by connecting portions 52A that are discontinuously and evenly spaced. A plurality of through holes 53A are formed between these connecting portions 52A. The rear end edge of the cap inner tube 52 is also discontinuous edges 52B that are divided by the connecting portions 52A. In this embodiment, the connecting portions 52A and the discontinuous edges 52B are formed in six locations.

[0024] The closed tip of the cap inner cylinder 52 is flush with the tip of the cap outer cylinder 51, and is surrounded by a continuous circumferential groove 53. The circumferential groove 53 communicates with the rear half of the interior of the cap outer cylinder 51 via the through hole 53A.

[0025] From rear opening 54, front barrel 11 (see FIGS. 1A and 1B and FIGS. 3A to 3C) described above is inserted. Locking projections 55 are multiple projections formed on the inner surface of cap outer tube 51 near the rear end thereof, intersecting the axial direction, and are locked to each other by elastically deforming from front to rear to overcome locking projections 11A1 (see FIGS. 2 and 3A-C) provided on front barrel 11. In this way, cap 50 is attached to barrel 10. In this embodiment, a total of four locking projections 55 are provided corresponding to the rounded side surfaces of the cap outer cylinder 51, as shown in FIG. 4A.

[0026] 4B and 4C, the guide piece 56 is formed as an inclined protrusion that connects the connecting portion 52A to the inner surface of the cap outer cylinder 51. In this embodiment, a total of six guide pieces 56 are equally spaced.

[0027] As shown in Figure 5C, when the front barrel 11 is inserted through the rear opening 54 of the cap 50 while sliding against its inner peripheral edge 54A, these multiple guide pieces 56 guide the reduced diameter portion 31 of the core surrounding member 30 and the tip end 23 of the ink supply core 20, thereby preventing the reduced diameter portion 31 and the tip end 23 from colliding with the discontinuous edge 52B and preventing damage.

[0028] (tail plug) 6A to 6C, the tail plug 60 is formed in a cylindrical shape as a whole, and has an insertion portion 61, a flange portion 62, and a head portion 63. The tip of the insertion portion 61 forms a tail portion 64. The insertion portion 61 is inserted into the rear body 12 from the rear opening 14 of the rear body 12 in the barrel 10, and closes the rear opening 14 (see FIG. 1B). The flange 62 fits tightly against the end face of the rear opening 14 to seal the inside of the rear body 12 and isolate the inside of the rear body 12 from the outside air. The head portion 63 is formed so as to extend rearward from the flange portion 62, and the cap 50 can be attached to this portion when writing.

[0029] The shape of the breech plug 60 is such that the insertion portion 61 and head portion 63 are formed to have circular cross sections in the transverse direction, but the flange portion 62 is formed to have a rounded rectangular cross section, the same as the cross section of the barrel 10. In other words, the flange portion 62 and the rear barrel 12 are shaped to match when the breech plug 60 is inserted into the rear opening 14 of the barrel 10.

[0030] It should be noted that another writing part (not shown) can be attached in place of the tail plug 60. Here, by making the outer diameter of the portion where the other writing part is inserted into the rear barrel 12 the same shape as the insertion portion 61 of the tail plug 60, the barrel 10 can be used for both a writing instrument 1 having a writing tip at only one end, as in this embodiment, and a writing instrument having writing tips at both ends.

[0031] (Filling) 1B is made of a cylindrical polyester fiber material that stores ink, and is housed inside rear barrel 12 of barrel tube 10. Furthermore, as shown in FIG. 2, the front end of padding 15 is located inside front grip portion 12A of rear body 12, slightly forward of boundary portion 12C, and is in contact with multiple ribs 12A1 (see FIG. 3C) formed in the axial direction on the inner surface of front grip portion 12A. On the other hand, the rear end of the padding 15 is positioned so as to come into contact with the tail portion 64 of the tail plug 60 that fits into the rear body 12. As a result, the padding 15 is sandwiched and fixed between the rib 12A1 of the front grip portion 12A and the tail portion 64 of the tail plug 60, as shown in FIG. 1B.

[0032] <Main components> Here, the ink supply core 20 and the core surrounding member 30, which are essential parts of this embodiment, will be described in detail.

[0033] [Ink supply core] As shown in FIG. 2, the ink supply core 20 has an outer circumferential portion 21, a flow path 22, a front end portion 23, a rear end portion 24 (see FIG. 1B), and a body portion 25. The ink supply core 20 is formed by extrusion molding of polyacetal resin, and has a generally cylindrical shape from the front to the rear, with the tip end 23 having a conical shape that tapers toward the front and the rear end 24 having a conical shape that tapers toward the rear, and the body 25 sandwiched between the tip end 23 and the rear end 24 having a cylindrical shape with an outer diameter the same as the outer diameter of the portions where the diameter tapers off of the tip end 23 and the rear end 24. Here, the ink supply core 20 may be made of a fiber bundle core, a sintered core, or the like.

[0034] (Outer periphery) The outer peripheral portion 21 forms the outer surface of the ink supply core 20. The tip of the front end portion 23 and the tip of the rear end portion 24 of the outer peripheral portion 21 are formed so that a flow path 22, which will be described later, is exposed. (flow path) The flow path 22 is formed along the axis inside the outer circumferential portion 21, and as described above, is exposed at the leading end 23 and the trailing end 24 of the outer circumferential portion 21. Here, when extrusion molding the ink supply core 20, a die with a small gap in the center is used, so that the flow path 22 is formed as a small gap in the center of the cross section. This gap as the flow path 22 exerts capillary force to retain ink. In this case, the outer periphery 21 and the flow path 22 of the ink supply core 20 are molded integrally. In the cross-sectional view of FIG. 10A, the flow path 22 is formed as a portion along the axis, that is, a portion occupying a diameter W2, and the portion occupying the periphery thereof is the outer circumferential portion 21. For example, the flow path 22 may be formed as a region having an irregularly shaped cavity at the inner periphery of the axial portion, as shown in the cross-sectional view of the ink supply core 20 in FIG. 10B , and the outer diameter W2 of the flow path may be determined as the diameter of a circle virtually circumscribing the cavity. The flow path 22 may also be formed as a region having a cavity with finer branches than the flow path 22 shown in FIG. 10B , as shown in the cross-sectional view of another example in FIG. 10C . In this example, the outer diameter W2 of the flow path is larger than in the example shown in FIG. 10B , and the flow path 22 occupies a larger proportion of the cross section of the ink supply core 20. Furthermore, when the flow path 22 is formed using a fiber bundle core or sintered core having a capillary structure, by forming the outer periphery 21 as a structure that coats the outer surface of the flow path 22, it becomes possible for this outer periphery 21 in the ink supply core 20 to be a thick portion on the outside of the flow path 22, and the outer surface of the flow path 22 can be fixed to the core surrounding member 30 without exposing it. In the ink supply core 20, the ink stored in the inner batting 15 is guided from the rear end 24 inserted into the inner batting 15 to the tip end 23 by capillary force.

[0035] [Core surrounding parts] As shown in FIGS. 7A to 7C, the core surrounding member 30 has, from the front side to the rear side, a tip portion 30A, a central portion 30B, and a rear end portion 30C. The tip portion 30A has a reduced diameter portion 31, a cylindrical portion 32, and an engagement portion 33. The central portion 30B is composed of an elastic portion . The rear end portion 30C is composed of a tubular portion . The ink supply core 20 passes through the through-hole 37, which penetrates each of these parts from the front end to the rear end, as shown in FIG. In this embodiment, the reduced diameter portion 31, cylindrical portion 32, engaging portion 33, elastic portion 34, and tubular portion 35 are integrally formed, and the basic shape of the portion other than the reduced diameter portion 31 is cylindrical. The lead surrounding member 30 is preferably formed from polyacetal resin from the viewpoints of low friction during writing, wear resistance, and creep resistance of the elastic portion 34.

[0036] (Reduced diameter part) As shown in FIG. 7C, the reduced diameter portion 31 is located on the front side of the lead surrounding member 30 and is formed in a tapered shape that reduces in diameter toward the front. A circular tip opening 31A is formed at the tip of the reduced diameter portion 31, and an opening rim portion 31B is formed around the tip opening 31A. On the other hand, the through portion 37 in the reduced diameter portion 31 is a first through portion 37A.

[0037] This first through portion 37A has a stop surface 37A1 that narrows in diameter toward the tip opening 31A, and the side of the tip portion 23 of the ink supply core 20 contacts and engages with this stop surface 37A1, causing the tip of the tip portion 23 of the ink supply core 20 to protrude outward (see Figure 2). 7C, the inner diameter of the first through portion 37A in the reduced diameter portion 31 increases rearward from the tip opening 31A. This shape corresponds to the conical shape of the outer peripheral surface of the tip portion 23 of the ink supply core 20.

[0038] (Cylindrical part) As shown in FIGS. 7A to 7C, cylindrical portion 32 is formed in a cylindrical shape that continues to the rear side of reduced diameter portion 31, has the same outer diameter as the outer diameter of the rear end of reduced diameter portion 31, and extends rearward. The through-hole 37 in the cylindrical portion 32 continues from the reduced diameter portion 31 to form a first through-hole 37A. The first through portion 37A in this cylindrical portion 32 is formed as a hole with a circular cross section having an inner diameter the same as the inner diameter of the rear end of the first through portion 37A in the reduced diameter portion 31, and is given an inner diameter larger than the outer diameter of the ink supply core 20 so that the ink supply core 20 can move in the axial direction.

[0039] (Engagement part) 7A to 7C, engaging portion 33 is provided continuously from the rear end of cylindrical portion 32 via a disk-shaped engaging piece 33A having an outer diameter larger than that of cylindrical portion 32. The outer diameter of engaging portion 33 is larger than that of cylindrical portion 32 and smaller than that of engaging piece 33A. Engaging portion 33 is formed in a substantially cylindrical shape with a notch in the axial direction in part of the side surface. Also inside this engaging portion 33, as shown in FIG. 7C, a first through portion 37A that penetrates through the cylindrical portion 32 is formed as a circular hole that has the same inner diameter and continues to extend rearward.

[0040] (elastic part) 7A to 7C, in this embodiment, the elastic portion 34 is formed as a double spiral spring that continues to the rear side of the engaging portion 33 and has an outer diameter that is approximately the same as the outer diameter of the rear end of the engaging portion 33. The cross section of this spiral spring is triangular, as shown in FIG. 7C. 7C, a second through portion 37B continuing from the rear end of the first through portion 37A is formed inside the spiral spring 34. The second through portion 37B has an inner diameter substantially the same as the inner diameter of the first through portion 37A and is formed as a circular hole extending rearward. The spiral spring is an example of the shape of the elastic portion 34.

[0041] The spiral spring serving as the elastic portion 34 is formed with a predetermined spring constant to accommodate a fine-point felt-tip pen or marking pen, and is configured to apply a spring force to the ink supply core 20 sufficient to allow it to move in the axial direction as described below.

[0042] (cylindrical part) As shown in FIGS. 7A to 7C, the tubular portion 35 is continuous with the rear end of the elastic portion 34, has an outer diameter substantially the same as the outer diameter of the elastic portion 34, and presents a cylindrical shape extending rearward. Also in this tubular portion 35, a third through-portion 37C having substantially the same inner diameter as the second through-portion 37B in the elastic portion 34 is formed as a circular hole extending rearward inside the tubular portion 35. A rear opening 35A is formed at the rear end of the tubular portion 35.

[0043] In this way, the core surrounding member 30 is composed of multiple parts from the front to the rear, and the ink supply core 20 is inserted from the rear opening 35A on the rear side of the core surrounding member 30 into the first through portion 37A, the second through portion 37B, and the third through portion 37C.

[0044] The shape of the spiral spring that constitutes the elastic portion 34 is not limited to this, and may be, for example, one with a rectangular cross section as shown in FIGS. 8A and 8B.

[0045] [Fixing the ink supply core to the core surrounding parts] Here, the fixing of the ink supply core 20 and the core surrounding member 30 will be described. As described above, the ink supply core 20 passes through the through-holes 37 of the core surrounding member 30 (the first through-hole 37A, the second through-hole 37B, and the third through-hole 37C).

[0046] In this embodiment, as shown in Figures 9A and 9B, the ink supply core 20 is fixed by compressing the punch fixing portion 36 by impact deformation using a punch on the outer surface of the tubular portion 35 that constitutes the rear end portion 30C of the core surrounding member 30, so that the protrusion 36A formed on the inner surface of the tubular portion 35 presses against the outer surface of the ink supply core 20. That is, the ink supply core 20 and the core surrounding member 30 are fixed only at the rear end portion 30C of the core surrounding member 30, and are not fixed at the tip portion 30A and the central portion 30B. As a result, the ink supply core 20 is not fixed inside the first through-hole 37A of the tip portion 30A and the second through-hole 37B of the center portion 30B, and is movable. Furthermore, when a large load is applied to the ink supply core 20 during writing, the ink supply core 20 retracts and acts as a cushion, making it possible to prevent the ink supply core 20 from breaking.

[0047] <Function of main parts> Based on the above-described configuration, in the writing instrument 1, the ink supply core 20 can be moved to the rear of the lead surrounding member 30 by writing pressure, which will be described with reference to FIGS. 2, 9A and 9B, and 10.

[0048] The writing instrument 1 in this embodiment has an ink supply core 20 and a lead surrounding member 30, and the ink supply core 20 is configured to move rearward at the tip of the lead surrounding member 30 due to writing pressure. The reason why the writing instrument 1 can freely change the width of the drawn line depending on the writing pressure is as follows.

[0049] First, when attempting to draw a thin line, a writing pressure of a predetermined level or less is applied to the writing instrument 1, and at this time, the tip portion 23 of the ink supply core 20 is in a position protruding a predetermined length (for example, about 5 mm) from the tip opening 31A of the lead surrounding member 30, as shown in Figures 9A and 10. With the tip portion 23 of the ink supply core 20 in this position, it is possible to draw a line on paper or the like (not shown). At this time, the elastic portion 34, which is a spiral spring, maintains the length L1 as shown in FIG. 9A, and the ink supply core 20 does not move rearward.

[0050] Next, when a thicker line is to be drawn, a writing pressure greater than the predetermined pressure is applied to the writing implement 1. Here, the ink supply core 20 is fixed in the third through-hole 37C of the tubular portion 35 of the core surrounding member 30 by the protrusion 36A of the tubular portion 35 (rear end portion 30C) of the core surrounding member 30, as shown in FIG. 9B.

[0051] On the other hand, the ink supply core 20 is not fixed in the first through-hole 37A and the second through-hole 37B at the tip portion 30A and the central portion 30B of the core surrounding member 30, and when writing pressure is applied, the ink supply core 20 tends to move backward. As a result, the ink supply core 20 fixed to the tubular portion 35 of the core surrounding member 30 pushes the tubular portion 35 backward against the biasing force of the elastic portion 34, and as shown in Figure 9B, the elastic portion 34, which has a length L1, extends backward by a length Lx to become a length L2. The spiral spring that constitutes this elastic portion 34 is set to have a spring constant that allows it to expand in response to the writing pressure applied to the ink supply core 20 when attempting to write bold characters (which is greater than the writing pressure applied to the ink supply core when attempting to write fine characters).

[0052] As a result, the tip 23 of the ink supply core 20 moves rearward to such an extent that its tip protrudes slightly from the tip opening 31A of the core surrounding member 30, creating a small gap between it and the opening periphery 31B surrounding the tip opening 31A. Ink is also supplied to the small gap between the tip 23 of the ink supply core 20 and the opening periphery 31B surrounding the tip opening 31A. At the same time, the tip 23 of the ink supply core 20 and the opening periphery 31B of the core surrounding member 30 simultaneously come into contact with paper or the like (not shown), allowing thicker lines to be drawn.

[0053] In this way, the writing instrument 1 of this embodiment is capable of changing the width of the drawn line to a thicker line even when the writing instrument 1 is a felt-tip pen or a marking pen equipped with an ink supply core 20 for fine writing. Furthermore, even if excessive writing pressure is applied, the ink supply core 20 remains movable and a load is applied to the core surrounding member 30, so it is possible to prevent poor writing due to buckling or crushing of the ink supply core 20.

[0054] <Protrusion dimension of the tip of the ink supply core from the tip opening of the core surrounding member> Next, the relationship between the length of the tip of the ink supply core and the projection dimension from the tip opening of the core surrounding member will be described. The protrusion dimension H1 (see FIG. 10) of the tip portion 23 of the ink supply core 20 from the tip opening 31A of the core surrounding member 30 is 0.05 to 0.7 mm when not writing. The protrusion dimension is more preferably in the range of 0.1 to 0.3 mm, and most preferably 0.2 mm. If the protrusion dimension is less than 0.05 mm, it becomes difficult to draw lines. If the protrusion dimension exceeds 0.7 mm, the distance between the ink supply core 20 and the core surrounding member 30 becomes too great, which can cause blurring and makes the ink supply core 20 more susceptible to breaking or buckling due to writing pressure.

[0055] <Relationship between the inner diameter of the tip opening of the core surrounding member and the outer diameter of the flow path of the ink supply core> Here, the inner diameter of the tip opening 31A of the ink supply core surrounding member 30 from which the tip portion 23 of the ink supply core 20 protrudes is set to W1 (mm), and the outer diameter of the flow path of the ink supply core 20 is set to W2 (mm). The results of an experiment to verify the state of fading of drawn lines using multiple types of ink are shown in Table 1 below. The inks used were two types of black ink (Ink A and Ink B) used in the applicant's products. The surface tension of Ink A was 50 m / N and the viscosity was 2.0 mPa·s. The surface tension of Ink B was 35 m / N and the viscosity was 4.0 mPa·s. In Table 1 below, the inventor drew a circle approximately 5 cm in diameter about five times, and the drawn lines were evaluated as follows: "A" indicates no fading, "B" indicates slight fading, and "C" indicates significant fading.

[0056] [Table 1]

[0057] Example 1 In Example 1, W1 = 0.95 mm and W2 = 0.49 mm. As a result, W1 - W2 = 0.46 mm. Slight blurring of the drawn lines was observed.

[0058] Example 2 In Example 2, W1 = 0.55 mm and W2 = 0.49 mm. As a result, W1 - W2 = 0.06 mm. As for the lines drawn, slight fading was observed in one of the two inks (ink A) in Example 1, but this was improved, so overall it was judged to be better than Example 1.

[0059] Example 3 In Example 3, W1 = 0.47 mm and W2 = 0.49 mm. As a result, W1 - W2 = -0.02 mm, which was below 0. With regard to the drawn lines, no smearing was observed for all types of ink used, and the results were good.

[0060] Example 4 In Example 4, W1 = 0.47 mm and W2 = 0.56 mm. As a result, W1 - W2 = 0.09 mm, which was evaluated to be almost the same as Example 3 and was the best result among all the Examples.

[0061] (Comparative Example) In the comparative example, W1 = 1.0 mm and W2 = 0.49 mm. As a result, W1 - W2 = 0.51 mm, exceeding 0.5 mm. With regard to the drawn lines, fading was observed for all ink types, with one type (Ink B) experiencing significant fading. In conclusion, it was judged to be undesirable.

[0062] In this way, it was found that when the value (W1-W2) obtained by subtracting the outer diameter W2 of the flow path of the ink supply core 20 from the inner diameter W1 of the tip opening 31A of the core surrounding member 30 from which the tip portion 23 of the ink supply core 20 protrudes is 0.5 mm or less, even if blurring of the drawn lines is observed, it is slight, and when it is less than 0, blurring is not observed.

[0063] From the above results, it was found that, with regard to the relationship between the inner diameter W1 of the tip opening 31A of the core surrounding member 30 and the outer diameter W2 of the flow path 22 of the ink supply core 20, the value obtained by subtracting the outer diameter W2 of the flow path of the ink supply core 20 from the inner diameter W1 of the tip opening 31A of the core surrounding member 30 from which the tip portion 23 of the ink supply core 20 protrudes is preferably 0.5 mm or less, and more preferably less than 0.

[0064] Although specific embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that the present invention is not limited to such embodiments, and that various other embodiments are possible within the scope of the present invention.

[0065] For example, although the embodiment has been described in which the tip portion 30A and the central portion 30B of the core surrounding member 30 are integrally formed, the central portion 30B may be configured as a separate body. For example, the tip portion 30A and the rear end portion 30C may be formed from the same resin material as in the embodiment, and a metal spring may be interposed between them as the central portion 30B.

[0066] Furthermore, although the ink storage means has been described as the padding 15, it may be in the form of an ink tank. [Explanation of symbols]

[0067] 1 writing implements 10 shaft cylinder 11 Tip shaft 11A Root part 11A1 Locking protrusion 11B Reduced diameter part 11C Tip 11D Locking surface 11E Air replacement vent 12 Rear shaft 12A Front grip part 12A1 Rib 12B Rear grip 12C Boundary 12D Slot 12E End 13 Front opening 14 Rear opening 15 Padding 20 ink supply core 21 outer periphery 22 flow path 23 tip 24 Rear end 25 Body 30 Core surrounding member 30A Tip 30B Center part 30C Rear end part 31 Reduced diameter part 31A Tip opening 31B Opening periphery 32 Cylindrical part 33 Engagement part 33A Engagement piece 34 Elastic part 35 Cylinder part 35A Rear opening 36 Punch fixing part 36A Protrusion 37 Penetration part 37A 1st penetration part 37A1 Stopping surface 37B 2nd penetration part 37C 3rd penetration part 40 gripping member 42 Front opening 42A Edge 43 Rear opening 43A End face 44 Locking piece 50 Cap 51 Cap outer tube 52 Cap inner cylinder 52A Connection part 52B Discontinuous Edge 53 Circumferential groove 53A Through hole 54 Rear opening 54A Inner edge 55 Locking protrusion 56 Guide piece 60 tail plug 61 insertion part 62 Tsuba 63 Head 64 Tail H1 protrusion dimension W1 Inner diameter of tip opening W2 Outer diameter of flow path

Claims

1. A shaft cylinder and an ink supply core housed inside the barrel and guiding ink by capillary force; a core surrounding member attached to the tip of the barrel, through which the ink supply core passes and from which the tip of the ink supply core protrudes; a cap attached to the tip of the barrel; and The cap has a cap outer cylinder and a cap inner cylinder formed in a cylindrical shape, The cap outer cylinder is formed into a cylindrical shape as a whole, has openings at the front and rear, and the tip portion of the barrel is inserted into the rear opening, The cap inner cylinder is formed in a cylindrical shape with a closed front end and an open rear end, and is housed in the front half of the cap outer cylinder, the open rear end portion of the cap inner cylinder is connected to the inner circumferential surface of the cap outer cylinder near the middle portion thereof by discontinuously and equally spaced connecting portions; the closed tip portion of the cap inner cylinder is flush with the tip of the cap outer cylinder, and its periphery is surrounded by a continuous circumferential groove; A writing instrument characterized in that it is formed with a plurality of guide pieces that are inclined protrusions that connect the connecting portion rearward to the inner surface of the cap outer tube and whose length in the front-to-back direction is greater than its width in the circumferential direction.

2. In the barrel, a front grip portion is formed at a rear portion of the tip portion to which the cap is attached, the front grip portion having a stepped diameter smaller than a rear grip portion formed at the rear of the tip portion, The front gripping portion is covered with a gripping member, A plurality of locking pieces are formed on the inside of the gripping member, protruding inward and formed as elongated ridges in the axial direction, 2. The writing implement according to claim 1, wherein the gripping member is attached to the barrel by fitting the plurality of locking pieces into a plurality of slots provided on the outer periphery of the front gripping portion.

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