Knock-type ballpoint pen

Abstract

To provide a ballpoint pen that can obtain a sufficient writing distance even with ink having a large particle diameter. [Solution] A knock-type ballpoint pen is provided which comprises a cylindrical barrel 20 that houses a refill 3 inside, the refill 3 consisting of an ink reservoir 30 that contains ink and a ballpoint pen tip 32 inserted into the tip of the ink reservoir 30 via a joint 31, a barrel body 2 that consists of an approximately conical tip member 21 that screws onto the tip of the barrel 20, and a knock mechanism 4 that extends or retracts the tip of the refill 3 from the tip of the barrel body 2, and by ensuring a sufficient ink flow path inside the ballpoint pen tip 32, the ballpoint pen 1 has a writing distance of 200 m or more.

Description

[Technical field]

[0001] The present invention relates to a knock-type ballpoint pen that can obtain a sufficient writing distance even when using ink with a large particle size. [Background technology]

[0002] In recent years, various pigments have been used as components of ballpoint pen ink. Among them, pigments of metal particles that give a metallic luster to the drawn lines, or reversible thermochromic microencapsulated pigments that can make the drawn lines colorless by frictional heat, have a relatively large particle size. If the particle size of the pigment used in the ink is large, the ink may clog the gap between the crimped part at the tip of the ballpoint pen and the writing ball, or the gap between the ball house in which the writing ball is stored and the writing ball. This causes the ink to smudge, and there is a problem that a sufficient writing distance cannot be ensured. In order to solve this problem, the moving distance of the writing ball within the ball house (hereinafter referred to as the clearance) has been increased.

[0003] However, if the clearance is increased, the writing ball may fall out of the ball house due to impact. In particular, in a knock-type ballpoint pen, such falling out is likely to occur due to the impact of knocking when storing the refill. Therefore, Patent Document 1 discloses a ballpoint pen in which the writing ball is less likely to fall out of the ball house. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5484186 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the ballpoint pen described in Patent Document 1 is less likely to cause the writing ball to fall out of the ball house, it consumes more ink than necessary and does not provide sufficient writing distance. In addition, not only does the crimped part come into contact with the paper surface during writing, causing wear to the crimped part, but the fibers of the paper are rubbed off, and the scraped off paper fibers can enter the ball house as the writing ball rotates, blocking the ink passage. Therefore, an object of the present invention is to provide a ballpoint pen that can obtain a sufficient writing distance even with ink having a large particle size. [Means for solving the problem]

[0006] The present invention includes a refill 3 having a ballpoint pen tip 32, which is a writing part, at the tip thereof, and A barrel body 2 that houses the refill 3; A coil spring 40 that biases the refill 3 rearward; a knock portion 41 provided at the rear portion of the barrel body 2 and disposed behind the refill 3 and interlocking with the refill 3; The knock-type ballpoint pen 1 is set to a writing position by pushing the knock portion 41 forward to cause the refill 3 to protrude from the tip of the barrel body 2, The ballpoint pen tip 32 includes a writing ball 33 and a holder 34 that holds the writing ball 33 at its tip. A crimped portion 34b that holds the writing ball 33 is provided at the tip of the holder 34, and the internal space of the holder 34 is formed with a ball house 35 that is provided at the tip of the holder 34 and into which the writing ball 33 is inserted, a back hole 37 that is provided from the rear end of the holder 34 toward the tip to the vicinity of the ball house 35, and an ink guide hole 36 that connects the back hole 37 and the ball house 35. The ball house 35 has a cylindrical surface 35a that is approximately parallel to the axis, a bottom surface 35b that is a conical surface that is continuous with the cylindrical surface 35a and tapers backward, and a ball seat 35c on which the curved surface of the writing ball 33 is transferred. Ink grooves 36a are formed at a plurality of equally spaced locations around the ink guide hole 36, and are radial grooves drilled from the ball house 35 toward the rear. A resilient member 38 for urging the writing ball 33 in a tip direction is inserted into the back hole 37, and a tip portion of the resilient member 38 is formed as an urging portion 38a that extends linearly in the tip direction, passes through the ink guide hole 36, and abuts against the rear end of the writing ball 33 to urge it. the maximum volume of ink contained in the refill 3 is 0.5 ml or more, the sphericity of the writing ball 33 is 0.5 μm or less, a clearance that is an amount by which the writing ball 33 can move in the axial direction of the ballpoint pen tip 32 within the holder 34 is less than 30 μm, the average particle diameter of the pigment used in the ink is 0.3 μm or more but less than the clearance, and the force that holds the writing ball 33 at the crimped portion 34b is equal to or less than the knock load when pressing the knock portion 41, The pressing load of the resilient member 38 is less than the weight of the shaft body 2, When the diameter of the writing ball 33 is A, the distance by which the writing ball 33 projects from the tip of the holder 34 is B, the clearance is C, the inner diameter of the cylindrical surface 35a of the ball house 35 is D, the inner diameter of the ink guide hole 36 is E, the outermost diameter of the ball seat 35c is F, and the wire diameter of the biasing portion 38a is G, then: The writing ball 33 is held by the crimped portion 34b so that (B+C)<0.4A. The ball house 35 is formed so that D≧(A+0.03 mm) and F<0.65A. The ink guide hole 3 is formed so that E≦0.6A, The biasing portion 38a is formed so that 0.4E≦G≦0.6E. The knock load is 5N or more. This allows for a writing distance of over 200m.

[0007] Here, "the force with which the crimped portion 34b holds the writing ball 33" refers to the ball holding force, which is the static load required to cause the writing ball 33 to fall out from the rear of the ballpoint pen tip 32 toward the front in the axial direction. Further, the “knock load” refers to the load required when a user presses knock portion 41 to advance or retract the tip of refill 3 from barrel body 2 . Furthermore, by setting the sphericity of the writing ball 33 to 0.5 μm or less, the rotation of the writing ball 33 is not impeded, and the ink can be ejected smoothly.

[0008] Furthermore, by making the pressing load of the resilient member 38 less than the weight of the barrel body 2, a smooth writing feel with the writing ball 33 can be provided. Furthermore, by forming the tip of ballpoint pen tip 32 so that (B+C)<0.4A, the distance that writing ball 33 protrudes from the writing tip is at most 40% of the ball diameter, making writing ball 33 less likely to fall off. Furthermore, cylindrical surface 35a of ball house 35 is formed so that D≧(A+0.03mm), so that diameter D of cylindrical surface 35a is 0.03mm or more wider than diameter A of writing ball 33, ensuring a sufficient ink flow path. Furthermore, ball seat 35c is formed so that F<0.65A, so that writing ball 33 rotates smoothly when writing and the opening of the groove is secured, ensuring a sufficient ink flow path.

[0009] Also, by forming the ink guide hole 36 so that E≦0.6A and forming the urging portion 38a so that 0.4E≦G≦0.6E, an ink passage can be secured. When shear thinning ink is used, the urging portion 38a moves up and down and left and right within the ink guide hole 36 during writing, stirring the ink and improving ink flow. Furthermore, if the knock load is set to 5N or more, it is possible to avoid the tip of the refill 3 being accidentally advanced from the barrel body 2, thereby preventing unnecessary ink stains. In addition, by forming an ink circulation hole in the joint 31 that is smaller in diameter than the press-fit portion with the ballpoint pen tip 32, it is possible to prevent the ball from flying off due to the knock impact.

[0010] Incidentally, by providing an erasing member 41a made of a soft material at the rear end of the knock portion 41, the impact applied to the ballpoint pen 1 when it is dropped with the knock portion facing downwards may be absorbed. In addition, the ink suitable for the present invention is characterized in that it contains at least colored resin particles having an average particle size of 1 μm or more and non-thermoplastic and non-colored particles having a glass transition point of less than 0° C., contains 5 to 30% by weight of colored resin particles based on the total amount of the ink composition, and has shear thinning properties that can be erased by the rubbing action of the erasing member 41a. In addition, the ink suitable for the present invention contains 5 to 30% by weight of a thermochromic microcapsule pigment having an average particle size of 1 μm or more, which is a thermochromic composition containing at least three essential components, an electron-donating color-forming organic compound, an electron-accepting compound, and a reaction medium that determines the temperature at which the color reaction between the two occurs, encapsulated in microcapsules, and is capable of changing or erasing color by the rubbing action of the erasing member 41a. Here, the "average particle size" is the D50 value measured by a particle size analyzer [Microtrac HRA9320-X100 (manufactured by Nikkiso Co., Ltd.)].

[0011] In addition, the outer diameter 34c of the crimped portion 34b provided at the tip of the holder 34 may be chamfered. This reduces the frictional resistance generated between the crimped portion 34b and the paper surface during writing, and suppresses wear of the crimped portion 34b and the scraping off of the fibers of the paper surface. This prevents the writing ball 33 from falling off due to writing and prevents smearing during writing. In addition, the ballpoint pen tip 32 of the ballpoint pen 1 according to the present invention may be provided with an inward protruding portion 37a at the tip portion of the back hole 37, which is in a position that contacts the rear end of each ink groove 36a. By providing the inward protruding portion 37a, even if the urging portion 38a of the elastic member 38 tilts toward the ink groove 36a during writing, it will abut against the inward protruding portion 37a before fitting into the ink groove 36a. Therefore, it is possible to prevent the urging portion 38a of the elastic member 38 from fitting into the ink groove 36a and blocking the ink passage. Furthermore, by forming an ink flow path that weaves between the inward protruding portions 37a, the ink outflow resistance is reduced, making it less likely that smearing will occur during writing.

[0012] A pressure mechanism 5 capable of applying pressure to the refill 3 from the rear end of the refill 3 may be provided at the rear end of the refill 3. Here, the "pressure mechanism 5" is a mechanism that applies pressure to the ink in the refill 3. Specifically, there is a method of sealing a pressurized gas in the space in the refill 3, or a method of designing the refill 3 so that a sealed space (pressurizing chamber 42c) is provided inside the barrel body 2 at the rear of the ink in the refill 3, and pressure is applied to the sealed space when knocking is performed, and this pressure is applied to the ink in the refill 3. If the pressure mechanism 5 is provided, the ink will come out sufficiently even if the ink viscosity is increased to prevent direct current, so a smooth writing experience can be obtained.

[0013] In the case where the pressurizing mechanism 5 is provided in the ballpoint pen 1 by providing an airtight space, a rubber elastic body such as an O-ring 52 may be provided behind the refill 3 to prevent air from entering when creating the airtight space inside the barrel 2. This O-ring 52 acts as a buffer member and absorbs the impact on the ballpoint pen 1 when knocking. This buffer member does not have to be the O-ring 52, and it is sufficient that it abuts against the rear end of the refill 3 and has an elastic effect. Effect of the Invention

[0014] Because the ballpoint pen of the present invention is configured as described above, even if ink with a large average particle size is used in the ballpoint pen, it is possible to provide a knock-type ballpoint pen that is less likely to cause the writing ball to fall off due to impact when knocking, is less likely to cause writing defects such as ink smearing, and can achieve a sufficient writing distance of 200 m or more. [Brief description of the drawings]

[0015] [Figure 1] 1 is a front cross-sectional view of a ballpoint pen according to a first embodiment. [Diagram 2] 1 is a front cross-sectional view of the tip of a ballpoint pen tip according to the present invention. [Diagram 3] 1 is an enlarged front view of the tip of a ballpoint pen tip according to the present invention. [Figure 4] This is a cross-sectional view taken along line II in Figure 3. However, the outer periphery of the holder and the writing ball are omitted. [Diagram 5] 1 is a partial cross-sectional view showing the state of a ballpoint pen tip holder and a resilient member according to the present invention, with the writing ball omitted. [Figure 6] FIG. 11 is a front cross-sectional view of a ballpoint pen according to a second embodiment. [Figure 7] FIG. 11 is a partial front cross-sectional view of a ballpoint pen according to a third embodiment. [Figure 8] FIG. 13 is a development view showing a rotor and a cam of a knock mechanism in a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] (First embodiment) As shown in FIG. 1, ballpoint pen 1 in the first embodiment is a knock-type ballpoint pen, and comprises a barrel body 2, a refill 3 housed in barrel body 2 so as to be movable axially forward and backward, and a knock mechanism 4 that causes the tip of the built-in refill 3 to protrude and retract from the tip of barrel body 2. (Shaft body 2) The barrel body 2 is made up of a cylindrical barrel tube 20 that houses the refill 3 therein, and a substantially conical tip member 21 that is screwed onto the tip portion of the barrel tube 20.

[0017] A clip member 22 is provided at the rear end of the barrel 20 for clamping the fabric of a pocket when the barrel 20 is inserted into the pocket of the user's clothing. The tip member 21 has an opening at the bottom and a screw groove formed on its inner peripheral surface. In this way, the tip member 21 is attached to the barrel 20. (Refill 3) The refill 3 is composed of an ink containing tube 30 containing ink, and a ballpoint pen tip 32 attached to the tip of the ink containing tube 30 via a joint 31. An ink circulation hole having a smaller diameter than the press-fit portion with the ballpoint pen tip 32 is formed in the joint 31.

[0018] Here, the maximum volume of ink contained in the ink containing tube 30 is 0.5 ml or more. The ink contained therein is an eraser-erasable ink that can be erased by an erasing member 41a described later, and the average particle diameter of the ink is 0.3 μm or more and less than a clearance (see FIG. 3) described later. A pressure mechanism (not shown) is provided at the rear end of the refill 3. Specifically, pressurized gas is sealed in the space inside the refill 3, and pressure is applied to the ink in the refill 3 from the rear end of the refill 3. As shown in FIG. 2, the ballpoint pen tip 32 is composed of a writing ball 33 and a holder 34 that holds the writing ball 33 at its tip.

[0019] The diameter of the writing ball 33 is 0.4 mm or less, and the sphericity of the writing ball 33 is 0.5 μm or less. The sphericity is measured using a sphericity measuring device (ROUNDTEST RA-2000 manufactured by Mitutoyo Corporation). If the diameter of the writing ball 33 is A, the writing ball protruding dimension, which is the distance by which the writing ball 33 protrudes from the tip of the holder 34 as shown in FIG. 3, is B, and the clearance, which is the amount by which the writing ball 33 can move in the axial direction of the ballpoint pen tip 32 within the holder 34, is C, the clearance is less than 30 μm, and the writing ball 33 is held in the holder 34 so that the relationship (B+C)<0.4A is satisfied.

[0020] As shown in Fig. 2, the tip of the outer periphery of holder 34 is formed with tapered portion 34a and crimped portion 34b formed by inwardly plastically deforming the tip of tapered portion 34a. Writing ball 33 is held by crimped portion 34b, and crimped portion 34b is formed so that the force with which crimped portion 34b holds writing ball 33 is equal to or less than the knock load described below. In addition, outer diameter 34c of crimped portion 34b shown in Fig. 3 is chamfered. As shown in Figure 5, the internal space of holder 34 is formed with a ball house 35 into which writing ball 33 is inserted inside tapered portion 34a, a back hole 37 that is provided from the rear end of holder 34 toward the tip end to near ball house 35, and an ink guide hole 36 that connects back hole 37 and ball house 35.

[0021] Ball house 35 has cylindrical surface 35a substantially parallel to the axis, bottom surface 35b which is a conical surface continuing from cylindrical surface 35a and tapering rearward, and ball seat 35c on which the curved surface of writing ball 33 is transferred to bottom surface 35b. As shown in Fig. 4, if the inner diameter of cylindrical surface 35a of ball house 35 is D, the inner diameter of ink guide hole 36 is E, and the outermost diameter of ball seat 35c is F, ball house 35 is formed so that D≧(A+0.03 mm) and F<0.65A. Furthermore, ink guide hole 36 is formed so that E≦0.6A, and ink grooves 36a, which are grooves that radially penetrate from the ball house 35 side to the tip of back hole 37, are formed at three equally spaced locations around ink guide hole 36, as shown in Figures 4 and 5.

[0022] As shown in FIG. 2, a resilient member 38, which is a helical spring that urges the writing ball 33 in the distal direction, is inserted into the back hole 37. As shown in FIG. 2 and FIG. 5, the distal end of the resilient member 38 is formed as a urging portion 38a that extends in the distal direction and passes through the ink guide hole 36 to abut against the rear end of the writing ball 33 and urges it. Here, assuming that the wire diameter of the urging portion 38a is G, the urging portion 38a is formed so that 0.4E≦G≦0.6E is satisfied. The pressing load of the resilient member 38 is equal to or less than the weight of the barrel body 2. Furthermore, as shown in FIG. 5, an inward protrusion 37a that protrudes inward is formed at the distal end of the back hole 37 at a position that abuts against the rear end of each ink groove 36a.

[0023] (Knock mechanism 4) Knocking mechanism 4 is a mechanism for extending the tip of refill 3 from barrel body 2 and retracting it into barrel body 2 . As shown in FIG. 1, the knock mechanism 4 is composed of a coil spring 40 that biases the refill 3 toward the rear end, a knock portion 41 provided at the rear end of the barrel 20, and a rotor 42 located between the knock portion 41 and the refill 3. Here, the knock load in this embodiment is 5N or more. In addition, an erasing member 41a is provided at the rear end of the knock portion 41. This erasing member 41a is an eraser and is made of a soft material that can erase the eraser-erasable ink described above. Since the erasing member 41a is made of a soft material, the impact applied to the ballpoint pen 1 when it is dropped can be absorbed by the erasing member 41a.

[0024] (Second embodiment) As shown in Figure 6, the ballpoint pen 1 in the second embodiment comprises a barrel body 2 which can be separated into two, a refill 3 housed in the barrel body 2 so as to be able to advance and retreat in the axial direction, a knock mechanism 4 which causes the tip of the built-in refill 3 to protrude and retract from the tip of the barrel body 2, and a pressure mechanism 5 which is supported by a rotor 42 which is part of the knock mechanism 4 and comes into contact with the refill 3. Here, the refill 3 differs from the first embodiment in that it is made up of an ink containing tube 30 and a ballpoint pen tip 32 attached directly to the tip of the ink containing tube 30, but as in the first embodiment, the ballpoint pen tip 32 may be attached to the ink containing tube 30 via a joint. Also, the structure of the ballpoint pen tip 32 is the same as in the first embodiment.

[0025] (Shaft body 2) As shown in FIG. 6, barrel body 2 comprises cylindrical front barrel 23 formed with a tapered tip, and cylindrical rear barrel 24 screwed onto the rear end of front barrel 23. The open front portion of the front barrel 23 is formed in a tapered cylindrical shape, and the open rear portion is formed thin-walled, with a screw groove (not shown) for fastening being threaded in the circumferential direction on its outer circumferential surface. Rear barrel 24 is formed in a cylindrical shape, and a screw groove (not shown) is threaded in the circumferential direction on the front inner peripheral surface thereof for detachable screw engagement with the rear part of front barrel 23, and a substantially elliptical anti-disengagement rib (not shown) is provided rearward of this screw groove protruding radially inward, with a plurality of such anti-disengagement ribs being arranged in parallel at predetermined intervals in the circumferential direction. Also, a clip member 22 serving as a stopper is integrally formed in the axial direction on the rear outer peripheral surface of rear barrel 24.

[0026] (Knock mechanism 4) As shown in Figure 6, knock mechanism 4 is made up of a coil spring 40 interposed between barrel body 2 and ink containing tube 30, a knock portion 41 provided at the rear end of rear barrel 24, a rotor 42 slidably fitted into the end portion of ink containing tube 30 via a gap, a number of cams 43 protruding from the outer circumferential surface of rotor 42, and a number of strips 44 protruding from the rear portion of the inner circumferential surface of barrel body 2. Coil spring 40 is fitted into the tip end of ink containing tube 30 and comes into contact with the open front peripheral edge of barrel body 2 , thereby elastically biasing ink containing tube 30 towards the rear of barrel body 2 .

[0027] Knocking portion 41 is a knocking operation portion for advancing or retracting the tip of refill 3 from barrel body 2, and is provided at the rear end of rear barrel 24. Rotor 42, which will be described later, is detachably and relatively rotatably fitted to the front of knocking portion 41. A knocking portion cam (not shown) that corresponds to rotor 42 is provided at the tip of knocking portion 41, and erasing member 41a capable of erasing ink is provided at the rear end. The rotor 42 is formed in a substantially bottomed cylindrical shape, and the closed bottom is fitted with the knock part 41. Then, every time the erasing member 41a of the knock part 41 is knocked, the rotor 42 rotates by a predetermined angle (15° to 60°, preferably 18° to 30°).

[0028] The rotor 42 is formed in a hollow, generally convex shape with an expanded diameter portion 42a and a reduced diameter portion 42b in succession, the interior of which is formed as a pressurized chamber (volume reduction space) 42c for outside air (air), and the inner circumferential surface is formed from the opening direction to the closed bottom direction into an expanded diameter surface 42d, an expanded diameter surface 42e, a reduced diameter surface 42f, and a reduced diameter surface 42g, and falling off from the axle body 2 is effectively prevented by an anti-fall-off rib (not shown) on the rear axle 24. A plurality of continuous sawtooth teeth (not shown) are provided in the circumferential direction on the step surface between the expanded diameter portion 42a and the reduced diameter portion 42b of the rotor 42. In addition, tapered step surfaces are formed between the maximum expanded diameter surface 42d and the expanded diameter surface 42e, between the expanded diameter surface 42e and the reduced diameter surface 42f, and between the reduced diameter surface 42f and the minimum reduced diameter surface 42g.

[0029] When writing, the rotor 42 thus configured slides toward the front of the barrel body 2 and fits deeply into the end of the ink containing tube 30, exerting a pressurizing effect on the end of the ink containing tube 30. In contrast, when not writing, the rotor 42 fits shallowly into the end of the ink containing tube 30, forming a large gap between the end of the ink containing tube 30 and the pressurizing chamber 42c. A plurality of cams 43 are arranged in a row and protrude from the outer circumferential surface of rotor 42, and are protruded at intervals of 60° or less, preferably 30° or less. Each cam 43 is slidably fitted between a plurality of strips 44 provided at the rear of the inner circumferential surface of shaft body 2.

[0030] A plurality of strips 44 are arranged in a row and protrude from the rear part of the inner circumferential surface of shaft body 2, and are protruded at intervals of 60° or less, preferably 30° or less. Each strip 44 is formed in a substantially linear shape in the axial direction of shaft body 2, and serves as a guide for cam 43. The tip surface of each strip 44 is cut out in the circumferential direction, and this cutout meshes with cam 43. That is, when the knock section 41 is knocked while not writing, the rotor 42 rotates, the cam 43 provided on the outer peripheral surface of the rotor 42 meshes with the strip 44, and the refill 3 protrudes from the front of the barrel body 2. At this time, the cam 43 meshes with the strip 44, and writing is possible because the refill 3 does not retract even when writing. When the knock section 41 is knocked again while writing, the rotor 42 rotates, the meshing between the strip 44 and the cam 43 is released, and each cam 43 is slidably inserted between the multiple strips 44, and the rotor 42 slides in the direction opposite to the ink containing tube 30. Then, each cam 43 is positioned between the multiple strips 44, and the ballpoint pen tip 32 protruding from the front of the barrel body 2 retracts, making it impossible to write.

[0031] (Pressure mechanism 5) The pressure mechanism 5 is a mechanism that applies pressure to the ink in the refill 3 . As shown in FIG. 6, the pressure mechanism 5 is slidably fitted into the rotor 42 and is composed of a sealing rubber holder 50 located opposite the end face of the ink containing tube 30, a pressure spring 51 interposed between the rubber holder 50 and the rotor 42, and an O-ring 52 fitted to the outer peripheral surface of the rubber holder 50 to ensure airtightness. The rubber holder 50 is made of synthetic resin such as polyacetal, polyoxymethylene, or polyformaldehyde and is molded into a generally cylindrical shape, with a fitting groove 50a cut out in the circumferential direction on the outer circumferential surface.

[0032] The pressure spring 51 is a coil spring having a larger elastic force than the coil spring 40, and functions to elastically urge the rubber holder 50 toward the end of the ink containing tube 30. One end of the pressure spring 51 is inserted and connected to the inside of the rubber holder 50 via an attachment rib (not shown), and the other end is inserted and connected to the reduced diameter portion 42b of the rotor 42 via an attachment rib (not shown). The pressure spring 51 is fully compressed before the rubber holder 50 retreats and contacts the step surface between the enlarged diameter surface 42e and the reduced diameter surface 42f of the rotor 42. The elastic forces of the pressure spring 51 and the coil spring 40 are formed so that the knock load of the entire ballpoint pen 1 is 5N or more.

[0033] The O-ring 52 is molded into an endless ring using elastic materials such as silicone rubber or NBR that have excellent heat resistance, cold resistance, ozone resistance, electrical properties, and oil resistance, and is fitted into the fitting groove 50a of the rubber holder 50. During writing, the O-ring 52 deforms and fits closely to the enlarged diameter surface 42e of the rotor 42, preventing outside air in the barrel body 2 from flowing into the pressurizing chamber 42c of the rotor 42, and allows compressed outside air to flow from the pressurizing chamber 42c to the end of the ink containing tube 30. This allows pressure to be applied to the ink containing tube 30, promoting the ejection of ink. During no writing, the O-ring 52 faces the enlarged diameter surface 42e of the rotor 42 across a gap, allowing outside air to flow into the pressurizing chamber 42c of the rotor 42. Therefore, the enlarged diameter surface 42e of the rotor 42 and the O-ring 52 of the rubber holder 50 are separated from each other to define a flow passage for the outside air, and the inside of the barrel body 2 and the pressurizing chamber 42c of the rotor 42 communicate with each other. Due to this communication, the pressurizing chamber 42c of the rotor 42 and the ink containing tube 30 are not pressurized. The O-ring 52 also serves as a buffer member that absorbs the impact when the ink containing tube 30 collides backward during a knock.

[0034] (Third embodiment) As shown in Figure 7, the ballpoint pen 1 in the third embodiment is composed of a barrel body 2, a refill 3 housed in the barrel body 2 so as to be able to advance and retreat in the axial direction, and a knock mechanism 4 that causes the nib of the built-in refill 3 to protrude and retract from the tip of the barrel body 2. Here, the barrel body 2 and the refill 3 are configured in the same manner as in the first embodiment. Also, the pressure mechanism is provided in the ballpoint pen 1 in the same manner as in the first embodiment. (Knock mechanism 4) As shown in Figure 7, the knock mechanism 4 is composed of a coil spring 40 interposed between the barrel body 2 and the ink containing tube 30, a knock portion 41 provided at the rear end of the barrel 20, a rotor 42 provided between the knock portion 41 and the refill 3, a number of cams 43 protruding from the outer circumferential surface of the rotor 42, and a rear barrel 45 formed integrally with the clip member 22 and having a number of strips 44 protruding from its inner circumferential surface.

[0035] The knock portion 41 and the rotor 42 each have a knock portion cam (not shown) and a knock cam (not shown), which are corresponding cam inclined surfaces, and are configured so that the rotor 42 rotates only in a fixed direction by a specified angle when a knock action is performed axially forward. Furthermore, when the pressure is released after the knocking action, the refill 3 is constantly biased backward by the coil spring 40, and the cam 43 of the rotor 42 and the corresponding strip 44 of the rear cylinder 45 rotate the rotor 42 in the same direction as the rotation caused by the knocking part 41 and the rotor 42. In other words, the rotor 42 rotates at a predetermined angle and completes one revolution at a certain point (two knocks in the above configuration), and repeats this operation. Also, the tip of the rotor 42 is constantly in contact with the refill 3, and the front-to-rear position of the cam 43 determines the pen tip position of the tip of the refill 3.

[0036] Although not shown, an erasing member is attached to the rear end of knock portion 41, as in the first embodiment. The knock load when pressing knock portion 41 is also 5N or more. Here, the configuration of the thread 44 in the third embodiment and the operation of the cam 43 of the rotor 42 that makes rotational and vertical movements in contact with the thread 44 when the knock portion 41 is pressed to transition from writing to non-writing will be described with reference to Fig. 8. Fig. 8 is a schematic diagram showing the positional relationship between the cam 43 of the rotor 43 and the thread 44, and shows the position of the cam 43 of the rotor 42 with respect to the expanded thread 44 formed on the inner surface of the rear cylinder 45. The top of the figure indicates the pen tip direction, and the cam 43 of the rotor 42 moves from left to right in the figure with each knock operation because a rotational force is given to the cam 43 of the rotor 42 by the cam mechanism of the knock portion 41 and the rotor 42 described above.

[0037] Figure 8(a) shows the state in which the tip of the refill 3 protrudes from the tip of the barrel body 2 when writing, and the cam 43 is fixed by being pressed against the first inclined surface 44a and the first vertical wall 44b of the strip 44 by the repulsive force of the coil spring 40. When the knock portion 41 is pressed from this state, the cam 43 advances upward in the figure until it reaches a position beyond the first vertical wall 44b. Then, the cam 43 is released from the restriction imposed by the first vertical wall 44b. As a result, due to the repulsive force of the coil spring 40 and the rotational action of the knock portion cam and the knock cam described above, the cam 43 rotates to the right as shown in Figure 8(b) and is pressed against the second inclined surface 44c of the strip 44.

[0038] Then, when the finger is released, the cam 43 rotates further and undergoes a first vertical movement to reach the position shown in Fig. 8(c). The vertical movement distance in this first vertical movement is defined as a first vertical movement distance α. At this time, the inclined surface of the cam 43 collides with the front half portion 44d of the third inclined surface of the strip 44 (hereinafter referred to as the "front half inclined surface"), and the impact is transmitted to the refill 3. Furthermore, the cam 43 slides and rotates on the first half slope 44d of the strip 44, and then undergoes a second vertical movement to reach the position shown in FIG. 8(d). The vertical movement distance in this second vertical movement is defined as a second vertical movement distance β. At this time, the slope of the cam 43 collides again with the second half portion 44e of the third slope of the strip 44 (hereinafter referred to as the "second half slope"), and the impact is transmitted to the refill 3.

[0039] Thereafter, the cam 43 slides and rotates along the rear inclined surface 44e of the strip 44, comes into contact with the second vertical wall 44f of the strip 44, and stops, reaching the pen tip storage position when not writing, as shown in FIG. 8(e). Conventionally, the above collision occurred only once, and the vertical movement distance at that time was approximately equal to the sum of the first vertical movement distance α and the second vertical movement distance β in the above configuration. In this way, by providing an axial step in the front and rear halves of the third inclined surface of the strip 44 to shorten the vertical movement distance of the cam 43 per one stroke, it is possible to mitigate the impact applied to the refill 3. EXAMPLES

[0040] For the ballpoint pen 1 shown in the first, second and third embodiments, the diameter A of the writing ball used in the ballpoint pen tip 32 was set to 0.38 mm, and the writing distance was measured under the following conditions using black ink used in a commercially available water-based ballpoint pen (UM-101ER, manufactured by Mitsubishi Pencil Co., Ltd.). With the ink containing tube 30 filled with ink, a writing test was performed using a writing test machine conforming to JIS standard S6039, with the writing speed set to 4.5 m / min, the writing angle set to 60°, and the writing load set to 0.98 N, by spiral writing on a writing test paper conforming to JIS standard P3201, and the writing distance was measured.

[0041] As a result of measuring the writing distance, it was found that all ballpoint pens 1 had a writing distance of at least 200 m. [Industrial Applicability]

[0042] The present invention can be applied to a knock-type ballpoint pen that employs ink containing relatively large particles. [Explanation of symbols]

[0043] 1 Ballpoint pen 2 Body 20 Pen barrel 21 tip member 22 clip member 23 tip shaft 24 Rear barrel 3 Refill 30 Ink reservoir tube 31 Joint 32 Ballpoint pen tip 33 Writing ball 34 Holder 34a Tapered portion 34b Crimped portion 34c Outside diameter of crimped part 35 Ball house 35a Cylindrical surface 35b Bottom surface 35c Ball seat 36 Ink guide hole 36a Ink groove 37 Back hole 37a Inner protrusion 38 Resilient member 38a Pressing portion 4 Knock mechanism 40 coil spring 41 knock portion 41a erasing member 42 rotor 42a enlarged diameter portion 42b reduced diameter portion 42c pressurizing chamber 42d maximum expansion surface 42e expansion surface 42f Reducing surface 42g Most reducing surface 43 Cam 44 Column 44a First slope 44b First vertical wall 44c Second slope 44d First half slope 44e Second half slope 44f Second vertical wall 45 Rear barrel 5 Pressurizing mechanism 50 Rubber holder 51 Pressure spring 52 O-ring A Diameter of writing ball B Dimension of writing ball protrusion C Clearance D Inner diameter of cylindrical surface E Inner diameter of ink guide hole F Outer diameter of ball seat G Wire diameter of the energizing part α First vertical movement distance β Second vertical movement distance

Claims

[Claim 1] A refill with a ballpoint tip at the tip, which is the writing part, A barrel body that houses the refill; A coil spring that biases the refill rearward; a knock portion provided at a rear portion of the barrel body, disposed behind the refill, and interlocking with the refill; A knock-type ballpoint pen in which the knock portion is pushed forward to cause the refill to protrude from the tip of the barrel body, thereby setting the refill in a writing position, The ballpoint pen tip includes a writing ball and a holder that holds the writing ball at a tip thereof, A crimped portion for holding the writing ball is provided at the tip of the holder, and the internal space of the holder is formed with a ball house that is provided at the tip of the holder and into which the writing ball is inserted, a back hole that is provided from the rear end of the holder toward the tip to the vicinity of the ball house, and a cylindrical ink guide hole that connects the back hole and the ball house, the ball house has a cylindrical surface substantially parallel to the axis, a bottom surface which is a conical surface that is continuous with the cylindrical surface and reduces in diameter toward the rear, and a ball seat on which the curved surface of the writing ball is transferred; Ink grooves are formed at a plurality of equally spaced locations around the ink guide hole, the ink grooves being grooves that extend radially from the ball house side to a tip end portion of the back hole, a resilient member for urging the writing ball in a tip direction is inserted into the back hole, and a tip portion of the resilient member is formed as a urging portion that extends linearly in the tip direction, passes through the ink guide hole, and comes into contact with the rear end of the writing ball to urge it, The diameter of the writing ball is 0.4 mm or less, the sphericity of the writing ball is 0.5 μm or less, the clearance which is the amount by which the writing ball can move in the axial direction of the ballpoint pen tip within the holder is less than 30 μm, and the average particle size of the pigment used in the ink is 0.3 μm or more and less than the clearance, When the diameter of the writing ball is A, the distance that the writing ball protrudes from the tip of the holder is B, the clearance is C, the inner diameter of the cylindrical surface of the ball house is D, the inner diameter of the cylindrical surface of the ink guide hole is E, the outermost diameter of the ball seat is F, and the wire diameter of the biasing portion is G, then The writing ball is held by the crimped portion so that (B+C)<0.4A. The ball house is formed so that D≧(A+0.03 mm) and F<0.65A. The ink guide hole is formed so that E≦0.6A, The biasing portion is formed so that 0.4E≦G≦0.6E. This ballpoint pen is characterized in that the writing distance is 200 m or more.

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