Writing implement

Abstract

A writing implement (1) is provided with a pen body (3), which is made of synthetic resin, at a front end part. The pen body (3) is provided with: an outer shell part (31) having an annular shape in a cross section; and a plurality of ribs (32) protruding radially inward from the inner wall of the outer shell part (31). The outer shell part (31) and the ribs (32) extend in an axial direction (da). An ink lead-out path (33) extending in the axial direction (da) is formed between the outer shell part (31) and the ribs (32). A first convex surface (3A) having a single radius of curvature in a longitudinal section is formed at the front end part of the pen body (3). A frontmost end (341) of the pen body (3) and an inner peripheral edge part (311) of the front end of the outer shell part (31) of the pen body (3) are disposed in the region of the first convex surface (3A).

Description

writing implements

[0001] The present invention relates to a writing instrument, and more particularly to a writing instrument having a pen body made of synthetic resin.

[0002] Conventionally, pen bodies made of synthetic resin have been known that have a convex curved front end (for example, JPH02-155797A).

[0003] When using the conventional pen body to write on a writing surface made of fabric, if the axis of the pen body is tilted relative to the writing surface, the fibers on the surface of the fabric may get caught on the inner peripheral edge of the front end of the outer casing of the pen body, making it difficult to write smoothly.Furthermore, when using the conventional pen body to write on a writing surface made of a smooth surface such as plastic (e.g., plastic film, plastic plate, etc.), there is insufficient contact between the front end of the pen body and the writing surface, which may result in smeared handwriting.

[0004] The present invention solves the above-mentioned conventional problems by providing a writing instrument that prevents the pen body from getting caught on the surface of the fabric when writing on fabric, allowing for smooth writing, and that ensures sufficient contact between the front end of the pen body and the writing surface when writing on a smooth surface such as plastic, eliminating the risk of smearing the handwriting.

[0005] A first aspect of the present invention is a writing instrument having a pen body made of synthetic resin at its front end, wherein the pen body has an outer casing that is ring-shaped in cross section and a plurality of ribs that protrude radially inward from the inner wall of the outer casing, the outer casing and the ribs extend in the axial direction, an ink discharge path that extends in the axial direction is formed between the outer casing and the ribs, a convex curved surface having a single radius of curvature in longitudinal section is formed at the front end of the pen body, and the frontmost end of the pen body and the inner peripheral edge of the front end of the outer casing of the pen body are located in the area of ​​the convex curved surface.

[0006] A second aspect of the present invention is a writing instrument according to the first aspect, characterized in that the pen body further has a second convex curved surface formed on the outer periphery of the front end of the outer casing behind the first convex curved surface and having a single radius of curvature in longitudinal section, the first convex curved surface including the front end of the pen body and the inner peripheral edge of the front end of the outer casing, the first convex curved surface and the second convex curved surface being smoothly connected circumferentially at the front end surface of the outer casing, and the radius of curvature of the first convex curved surface being greater than the radius of curvature of the second convex curved surface.

[0007] A third aspect of the present invention is a writing instrument according to the first or second aspect, wherein when the axial distance between the inner circumferential edge of the front end of the outer casing of the pen body and the frontmost end of the pen body is L and the maximum inner diameter of the inner circumferential edge of the front end of the outer casing of the pen body is D, the distance L is within the range of 10% to 25% of the maximum inner diameter D.

[0008] According to the present invention, when writing on fabric, the pen body is prevented from getting caught on the surface of the fabric, allowing for smooth writing, and when writing on a smooth plastic surface, sufficient contact is achieved between the front end of the pen body and the writing surface, preventing the writing from smearing.

[0009] It is a longitudinal sectional view of the main part of the embodiment of the writing implement of the present invention. It is an enlarged view of the main part of the pen body of Figure 1. It is an enlarged sectional view of the line AA of Figure 2.

[0010] A writing instrument according to an embodiment of the present invention is shown in Figures 1 to 3. In the drawings attached to this specification, the scale and aspect ratios have been appropriately changed and exaggerated from those of the actual objects for the sake of ease of illustration and understanding.

[0011] In this specification, the direction in which the central axis Ac of the writing instrument 1 extends (longitudinal direction, vertical direction in a longitudinal cross section) is referred to as the axial direction da, the direction perpendicular to the axial direction da is referred to as the radial direction, and the direction along the circumference around the central axis Ac is referred to as the circumferential direction. Along the axial direction da, the side that approaches a writing surface such as a piece of paper when writing (the lower side in a longitudinal cross section) is referred to as the front, and the side that moves away from the writing surface (the upper side in a longitudinal cross section) is referred to as the rear. Along the radial direction, the side that approaches the central axis Ac is referred to as the inside, and the side that moves away from the central axis Ac is referred to as the outside.

[0012] The writing instrument 1 of this embodiment comprises a barrel 2, a pen body 3, and an ink occlusion body 4. The pen body 3 is attached to the front end of the barrel 2. The ink occlusion body 4 is housed inside the barrel 2 and connected to the rear end of the pen body 3.

[0013] - Barrel The barrel 2 is a cylindrical body extending in the axial direction da. The barrel 2 may be formed from a synthetic resin (e.g., polypropylene). The front end of the barrel 2 is tapered. A mounting hole 21 extending in the axial direction da is provided at the front end of the barrel 2. A plurality of longitudinal ribs extending in the axial direction da are integrally formed on the inner circumferential surface of the mounting hole 21. The pen body 3 is press-fitted into the mounting hole 21, and the outer circumferential surface of the pen body 3 and the longitudinal ribs of the mounting hole 21 are pressed against each other. Air passages are formed between adjacent longitudinal ribs in the circumferential direction, allowing air to circulate between the outside air and the interior of the barrel 2. An ink occluder 4 is housed inside the barrel 2. The ink occluder 4 may be, for example, a synthetic resin fiber bundle (e.g., a polyester fiber bundle). The ink occluder 4 is impregnated with ink (e.g., oil-based marking pen ink). The rear end (connecting portion 39 ) of the pen element 3 is thrust into the front end of the ink occlusion body 4 , thereby connecting the pen element 3 to the ink occlusion body 4 .

[0014] Pen Body The pen body 3 is made of synthetic resin (e.g., polyacetal). The pen body 3 is a rod-shaped body with a circular cross section. The pen body 3 may be produced by extrusion molding. The pen body 3 includes a front portion 34, a first tapered portion 35, a second tapered portion 36, an intermediate portion 37, a rear portion 38, and a connecting portion 39. The front portion 34 has a small outer diameter. The first tapered portion 35 is connected to the front portion 34 and located rearward of the front portion 34. The first tapered portion 35 extends forward so as to approach the central axis Ac. The second tapered portion 36 is connected to the first tapered portion 35 and located rearward of the first tapered portion 35. The second tapered portion 36 extends forward so as to approach the central axis Ac. In a cross section (longitudinal cross section) including the central axis Ac, the angle between the first tapered portion 35 and the central axis Ac is larger than the angle between the second tapered portion 36 and the central axis Ac. The intermediate portion 37 is connected to the second tapered portion 36 and located rearward of the second tapered portion 36. The intermediate portion 37 has a cylindrical shape with a larger outer diameter than the front portion 34. The rear portion 38 is connected to the intermediate portion 37 and located rearward of the intermediate portion 37. The rear portion 38 has a cylindrical shape with an outer diameter larger than the front portion 34 but smaller than the intermediate portion 37. The connecting portion 39 is connected to the rear portion 38 and located rearward of the rear portion 38. The connecting portion 39 has a pointed shape facing rearward.

[0015] The pen body 3 has an outer shell 31 and multiple ribs 32 (321, 322). The outer shell 31 has a circular cross section. Each rib 32 protrudes radially inward from the inner wall of the outer shell 31. Each rib 32 is formed integrally with the outer shell 31. The outer shell 31 and each rib 32 extend in the axial direction da. An ink lead-out path 33 extending in the axial direction da is formed between the outer shell 31 and each rib 32. The front end of the ink lead-out path 33 opens forward at a front portion 34 of the pen body 3. In the ink lead-out path 33, ink flows from the ink occlusion body 4 toward the front portion 34 of the pen body 3 due to capillary force.

[0016] The ribs 32 include a plurality of large protrusions 321 that extend generally radially to the vicinity of the central axis Ac, and a plurality of small protrusions 322 that are formed between adjacent large protrusions 321 in the circumferential direction. The gaps between the ribs 32 on the inner wall of the outer shell 31 may be set uniform. In this case, the shape of the opening of the ink lead-out path 33 can be made uniform at the inner peripheral edge 311 at the front end of the outer shell 31. This allows for a uniform amount of ink to be ejected regardless of the orientation of the outer peripheral surface of the pen head 3 during writing.

[0017] In a longitudinal cross section, the pen body 3 has a first convex curved surface (convex curved surface) 3A with a single radius of curvature at its front end. A second convex curved surface (another convex curved surface) 3B with a single radius of curvature is formed on the outer periphery 312 at the front end of the outer casing 31 behind the first convex curved surface 3A. The radius of curvature of the first convex curved surface 3A is greater than the radius of curvature of the second convex curved surface 3B. The radius of curvature of the first convex curved surface 3A is preferably in the range of 0.5 mm to 0.6 mm, and the radius of curvature of the second convex curved surface 3B is preferably in the range of 0.25 mm to 0.35 mm. This allows the first convex curved surface 3A and the second convex curved surface 3B to be easily connected at the front end surface of the outer casing 31. In this embodiment, as an example, the radius of curvature of the first convex curved surface 3A is set to 0.55 mm, and the radius of curvature of the second convex curved surface 3B is set to 0.3 mm.

[0018] The foremost end 341 of the pen body 3 and the inner peripheral edge 311 of the front end of the outer casing 31 may be located in the area of ​​the first convex curved surface 3A. That is, the first convex curved surface 3A may include the foremost end 341 of the pen body 3 and the inner peripheral edge 311 of the front end of the outer casing 31. In other words, the foremost end 341 of the pen body 3 and the inner peripheral edge 311 of the front end of the outer casing 31 may be located on the first convex curved surface 3A. The second convex curved surface 3B is formed on the outer peripheral edge 312 of the front end of the outer casing 31. The first convex curved surface 3A and the second convex curved surface 3B are smoothly connected to each other at the front end of the outer casing 31 (i.e., the area between the inner peripheral edge 311 of the front end of the outer casing 31 and the outer peripheral edge 312 of the front end of the outer casing 31). A connection point 313 where the first convex curved surface 3A and the second convex curved surface 3B are connected to each other is located on the front end surface (outer surface of the front end portion) of the outer shell 31.

[0019] The outer peripheral surface of the outer shell 31 behind the second convex curved surface 3B is formed with a straight outer peripheral surface 342. The second convex curved surface 3B and the straight outer peripheral surface 342 are smoothly connected to each other. The outer diameter of the straight outer peripheral surface 342 behind the second convex curved surface 3B may be set to 1.0 mm or more (e.g., 1.10 mm), thereby ensuring a sufficient area for the first convex curved surface 3A.

[0020] Let L be the distance in the axial direction da between the inner circumferential edge 311 at the front end of the outer casing 31 of the pen body 3 and the foremost end 341 of the pen body 3, and let D be the maximum inner diameter of the inner circumferential edge 311 at the front end of the outer casing 31 of the pen body 3. The distance L may be set to 10% to 25% of the maximum inner diameter D (0.1≦L / D≦0.25). Preferably, the distance L is set to 15% to 25% of the maximum inner diameter D (0.15≦L / D≦0.25). The distance L is preferably set to 0.16 mm or less. The maximum inner diameter D is preferably set to 0.65 mm or more. For example, the distance L is set to 0.14 mm, the maximum inner diameter D is set to 0.74 mm, and the distance L is set to 18.9% of the maximum inner diameter D.

[0021] The writing instrument 1 of this embodiment is a writing instrument that has a pen body 3 made of synthetic resin at its front end, and the pen body 3 has an outer casing 31 that is ring-shaped in cross section and a plurality of ribs 32 that protrude radially inward from the inner wall of the outer casing 31, the outer casing 31 and the ribs 32 extending in the axial direction da, an ink guide path 33 extending in the axial direction da is formed between the outer casing 31 and the ribs 32, a first convex curved surface 3A that has a single radius of curvature in longitudinal section is formed at the front end of the pen body 3, and the frontmost end 341 of the pen body 3 and the inner peripheral edge 311 of the front end of the outer casing 31 of the pen body 3 are positioned in the area of ​​the first convex curved surface 3A.

[0022] When writing on a fabric surface with the writing instrument 1 of this embodiment, with the axis of the pen body 3 tilted relative to the fabric surface, fibers on the fabric surface are prevented from getting caught on the inner peripheral edge 311 at the front end of the outer casing 31 of the pen body 3, allowing for smooth writing. If the convex curved surface 3A at the front end (top) 341 of the pen body 3 and the surface including the inner peripheral edge 311 at the front end of the outer casing 31 of the pen body 3 were not a single convex curved surface but were composed of different surfaces (for example, a combination of a convex curved surface and another convex curved surface with a different shape, or a combination of a convex curved surface and a tapered surface), the inner peripheral edge 311 at the front end of the outer casing 31 of the pen body 3 could have an extremely sharp shape. As a result, when writing on a fabric surface with the axis of the pen body 3 tilted relative to the fabric surface, fibers on the fabric surface could get caught on the inner peripheral edge 311 at the front end of the outer casing 31 of the pen body 3. Furthermore, with the writing instrument 1 of this embodiment, a convex curved surface 3A with a large radius of curvature can be formed over a wide area at the front end of the pen body 3. As a result, when the writing instrument 1 of this embodiment is used to write on a smooth plastic surface, sufficient contact is achieved between the front end of the pen body 3 and the writing surface, and there is no risk of smearing of handwriting.

[0023] In the writing instrument 1 of this embodiment, the pen body 3 further has a second convex curved surface 3B formed on the outer periphery 312 of the front end of the outer casing 31 behind the first convex curved surface 3A and having a single radius of curvature in a longitudinal section, the first convex curved surface 3A includes the front end 341 of the pen body 3 and the inner peripheral edge 311 of the front end of the outer casing 31, the first convex curved surface 3A and the second convex curved surface 3B are smoothly connected circumferentially at the front end surface of the outer casing 31, and the radius of curvature of the first convex curved surface 3A is greater than the radius of curvature of the second convex curved surface 3B.

[0024] According to the writing instrument 1 of this embodiment, the above-described configuration further prevents the inner peripheral edge 311 at the front end of the outer casing 31 of the pen body 3 from forming a sharp angle. Therefore, when writing on a fabric surface with the axis of the pen body 3 tilted relative to the fabric surface, it is possible to further prevent fibers on the fabric surface from getting caught on the inner peripheral edge 311 at the front end of the outer casing 31 of the pen body 3. Furthermore, when writing on a smooth plastic surface using the writing instrument 1 of this embodiment, sufficient contact is obtained between the front end of the pen body 3 and the writing surface, further preventing smearing of handwriting.

[0025] In the writing instrument 1 of this embodiment, when the axial distance da between the inner peripheral edge 311 at the front end of the outer casing 31 of the pen body 3 and the frontmost end 341 of the pen body 3 is L and the maximum inner diameter of the inner peripheral edge 311 at the front end of the outer casing 31 of the pen body 3 is D, the distance L is within the range of 10% to 25% (preferably 15% to 25%) of the maximum inner diameter D.

[0026] According to the writing instrument 1 of this embodiment, the above-described configuration prevents the pen head 3 from getting caught on the surface of fabric when writing on it, allowing for smooth writing. Furthermore, when writing on a smooth plastic surface, sufficient contact is achieved between the front end of the pen head 3 and the writing surface, more effectively preventing smearing of handwriting.

[0027] If the distance L is less than 10% of the maximum inner diameter D, when writing with the axis of the pen body 3 tilted relative to the writing surface, sufficient contact between the front end of the pen body 3 and the writing surface may not be achieved, resulting in smeared handwriting.If the distance L is more than 25% of the maximum inner diameter D, when writing on a fabric surface with the axis of the pen body 3 tilted relative to the fabric surface, fibers on the fabric surface may get caught on the inner peripheral edge 311 at the front end of the outer casing 31 of the pen body 3.

Claims

1. A writing implement having a pen body made of synthetic resin at its front end, wherein the pen body has an outer casing that is annular in cross section and a plurality of ribs that protrude radially inward from the inner wall of the outer casing, the outer casing and the ribs extend in the axial direction, an ink guide path that extends in the axial direction is formed between the outer casing and the ribs, a first convex surface having a single radius of curvature in longitudinal section is formed at the front end of the pen body, and the frontmost end of the pen body and the inner peripheral edge of the front end of the outer casing of the pen body are located in the area of ​​the first convex surface.

2. The writing implement described in claim 1, characterized in that the pen body further has a second convex curved surface formed on the outer periphery of the front end of the outer casing behind the first convex curved surface and having a single radius of curvature in vertical cross section, the first convex curved surface including the front end of the pen body and the inner peripheral edge of the front end of the outer casing, the first convex curved surface and the second convex curved surface being smoothly connected circumferentially at the front end surface of the outer casing, and the radius of curvature of the first convex curved surface being greater than the radius of curvature of the second convex curved surface.

3. A writing instrument as described in claim 1 or 2, characterized in that when the axial distance between the inner peripheral edge of the front end of the outer casing of the pen body and the frontmost end of the pen body is L and the maximum inner diameter of the inner peripheral edge of the front end of the outer casing of the pen body is D, the distance L is within the range of 10% to 25% of the maximum inner diameter D.

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