JP2023163178A - Ballpoint pen tip, ballpoint pen refill and ballpoint pen - Google Patents

Abstract

To increase the amount of ink supplied from a hollow tube to a ball in a ballpoint pen tip having the hollow tube located behind the ball.SOLUTION: A ballpoint pen chip 40 includes a ball 42, a chip body 70 having a ball holding chamber 71 that holds the ball 42, and a hollow tube 90 made of synthetic resin arranged so as to be able to contact the ball 42 from the rear. The outer diameter D90 of the hollow tube 90 is larger than the outer diameter D42 of the ball 42.SELECTED DRAWING: Figure 4

Description

The present invention relates to a ballpoint pen tip, a ballpoint pen refill, and a ballpoint pen.

Conventionally, a ballpoint pen tip has been used in a ballpoint pen, which includes a ball and a tip body having a ball holding chamber for holding the ball. Patent Document 1 discloses a ballpoint pen that includes a ball, a tip having a ball holding chamber, and a hollow tube disposed behind the ball. In this ballpoint pen, ink in the refill is mainly supplied to the ball through a hollow tube. The ink supplied to the ball is transferred from the ball to the writing surface as the ball presses against the writing surface, such as paper, and forms handwriting on the writing surface.

JP 2021-102295 Publication

In conventional ballpoint pens with a ballpoint tip that has a hollow tube located behind the ball, if the amount of ink supplied from the hollow tube to the ball is not sufficient, the handwriting formed by the ballpoint pen may be interrupted. , handwriting may become blurry. Therefore, in a ballpoint pen in which ink in a ballpoint pen refill is mainly supplied to the ball through a hollow tube, it is desired to increase the amount of ink supplied from the hollow tube to the ball.

The present invention has been made with these points in mind, and it is an object of the present invention to increase the amount of ink supplied from the hollow tube to the ball in a ballpoint pen tip having a hollow tube located behind the ball. With the goal.

The ballpoint pen tip according to the present invention is
[1] Ball and
a chip body having a ball holding chamber that holds the ball;
A hollow tube made of synthetic resin is arranged so as to be able to contact the ball from the rear,
The outer diameter of the hollow tube is larger than the outer diameter of the ball, which is a ballpoint pen tip.

The ballpoint pen tip according to the present invention is
[2] The ballpoint pen tip according to [1] above, wherein the outer diameter of the hollow tube is 1.05 times or more and 2.0 times or less the outer diameter of the ball.

The ballpoint pen tip according to the present invention is
[3] The ballpoint pen tip according to [1] or [2] above, wherein the outer diameter of the hollow tube is larger than the inner diameter of the ball holding chamber.

The ballpoint pen tip according to the present invention is
[4] Any of the above [1] to [3], wherein the hollow tube includes a hollow tube inner hole extending in the axial direction and a plurality of groove-like portions communicating with the hollow tube inner hole and extending radially. or the ballpoint pen tip described in one of the above.

The ballpoint pen tip according to the present invention is
[5] The ballpoint pen tip according to [4] above, wherein the distance from the central axis of the hollow tube to the outer end of the groove in the radial direction is greater than 1/2 of the outer diameter of the ball. be.

The ballpoint pen tip according to the present invention is
[6] According to [4] or [5] above, the distance from the central axis of the hollow tube to the outer end of the groove in the radial direction is greater than 1/2 of the inner diameter of the ball holding chamber. The ballpoint pen tip is as described.

The ballpoint pen tip according to the present invention is
[7] The ballpoint pen tip according to any one of [1] to [6] above, including a resilient member that urges the hollow tube forward.

The ballpoint pen tip according to the present invention is
[8] A slide member that includes the hollow tube and is movable in the axial direction;
further comprising a fixing member disposed behind the slide member and fixed to the chip body,
The elastic member is arranged between the slide member and the fixed member,
The ballpoint pen tip according to [7], wherein a gap is formed between the rear end of the slide member and the front end of the fixed member.

The ballpoint pen tip according to the present invention is
[9] The ballpoint pen tip according to any one of [1] to [8] above, including a resilient member that urges the ball forward.

The ballpoint pen refill according to the present invention includes:
[10] A ballpoint pen refill comprising the ballpoint pen tip according to any one of [1] to [9] above, and an ink storage cylinder that stores ink.

The ballpoint pen according to the present invention includes:
[11] A ballpoint pen equipped with the ballpoint pen refill described in [10] above.

According to the present invention, in a ballpoint pen tip having a hollow tube arranged behind the ball, it is possible to increase the amount of ink supplied from the hollow tube to the ball.

FIG. 1 is a diagram for explaining one embodiment of the present invention, and is a longitudinal sectional view showing an example of a ballpoint pen in a retracted state. FIG. 2 is a longitudinal sectional view showing the ballpoint pen of FIG. 1 in a protruding state. FIG. 3 is an enlarged longitudinal sectional view of the ballpoint pen tip of the ballpoint pen of FIG. 2. FIG. FIG. 4 is an enlarged vertical cross-sectional view showing the vicinity of the ball of the ballpoint pen tip of FIG. 3. FIG. FIG. 5 is a diagram showing the hollow tube of the ballpoint pen tip of FIG. 4 viewed from the front. FIG. 6 is a longitudinal sectional view showing a modified example of a ballpoint pen tip. FIG. 7 is an enlarged longitudinal sectional view showing the vicinity of the ball of the ballpoint pen tip of FIG. 6. FIG. FIG. 8 is a longitudinal sectional view showing another modification of the ballpoint pen tip. FIG. 9 is an enlarged longitudinal sectional view showing the vicinity of the tip body of the ballpoint pen tip of FIG. 8. FIG. FIG. 10 is a longitudinal sectional view showing still another modification of the ballpoint pen tip. FIG. 11 is an enlarged longitudinal sectional view showing the vicinity of the tip body of the ballpoint pen tip of FIG. 10.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In addition, in the drawings attached to this specification, for convenience of illustration and ease of understanding, the scale, vertical and horizontal dimension ratios, etc. are appropriately changed and exaggerated from those of the actual drawings.

In addition, terms such as "parallel," "perpendicular," and "identical," and values of length and angle used in this specification that specify shapes, geometric conditions, and their degree, etc., are strictly The term shall be interpreted to include the extent to which similar functions can be expected, without being bound by meaning.

In this specification, the direction in which the central axis A of the ballpoint pen 10 extends (the longitudinal direction, the vertical direction in a vertical cross-sectional view) 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 A is referred to as the axial direction da. The direction of the circumferential direction is defined as the circumferential direction. Further, along the axial direction da, the pen tip side is defined as the front, and the side opposite to the pen tip is defined as the rear. Further, along the radial direction, the side approaching the center axis A is called the inside or inside, and the side moving away from the center axis A is called the outside or outside.

FIG. 1 is a diagram for explaining an embodiment of the present invention, and is a longitudinal sectional view showing an example of a ballpoint pen 10 in a retracted state, and FIG. 2 is a longitudinal sectional view showing an example of a ballpoint pen 10 in a protruding state. be. The ballpoint pen 10 includes a barrel 20, a ballpoint pen refill 30 built into the barrel 20, and a mechanism 12 for making the tip of the ballpoint pen refill 30 protrude and retract from the barrel 20.

The shaft cylinder 20 includes a front shaft 22, a grip member 24 disposed surrounding the outer surface of the front shaft 22, a rear shaft 26 connected to the front shaft 22, and a clip 28 provided on the outer peripheral surface of the rear shaft 26. Contains. The central axis of the barrel 20 coincides with the central axis A of the ballpoint pen 10. The front shaft 22 is provided at the front end and has a front end opening 22a through which the tip of the ballpoint pen tip 40 of the ballpoint pen refill 30 can emerge and retract. The rear shaft 26 is attached to the front shaft 22. In particular, in the illustrated example, the female threaded portion formed on the inner surface of the front end of the rear shaft 26 is screwed into the male threaded portion formed on the outer surface of the rear end of the front shaft 22, so that the rear shaft 26 is attached to the front shaft 22. The grip member 24 is intended to be gripped by the user's fingers when writing with the ballpoint pen 10. The front shaft 22 and the rear shaft 26 are made of resin, for example, and the grip member 24 is made of rubber or elastomer, for example.

The retracting mechanism 12 moves the ballpoint pen 10 into a retracted state in which the tip of the ballpoint pen tip 40 is retracted from the front end opening 22a of the front shaft 22, and a protruding state in which the tip of the ballpoint pen tip 40 protrudes from the front end opening 22a. This is a mechanism for switching alternately. In FIG. 1, the ballpoint pen 10 is shown in a retracted state, and in FIG. 2, the ballpoint pen 10 is shown in an extended state. The retracting mechanism 12 includes an operating section 14 and a resilient member 16. In the illustrated example, the operating portion 14 is a knocking member that protrudes rearward from the rear end of the shaft tube 20 (rear shaft 26). Note that the present invention is not limited to this, and the operating section 14 may be, for example, a clip 28 that is arranged to be movable back and forth with respect to the shaft tube 20 (rear shaft 26). The resilient member 16 is, for example, a coil spring. The resilient member 16 is compressed between the inner stage 22b formed on the inner surface of the barrel 20 (front shaft 22) and the front surface of the collar 54 formed on the outer surface of the inner barrel 50 of the ballpoint pen refill 30. It is located in the state.

As shown in FIG. 1, in the retracted state, the ballpoint pen refill 30 is urged backward by the resilient force of the resilient member 16, so that the tip of the ballpoint pen tip 40 is pushed into the front end opening 22a. I've been immersed in it since then. When the user pushes the operating section 14 forward with his/her finger, the ballpoint pen refill 30 moves forward, and the tip of the ballpoint pen tip 40 protrudes forward from the front end opening 22a. Even when the user releases his/her finger from the operating section 14, the ballpoint pen refill 30 maintains the state in which the tip of the ballpoint pen tip 40 protrudes forward from the front end opening 22a. When the user pushes the operating section 14 forward again with his or her finger, the ballpoint pen refill 30 moves forward by a small distance. When the user releases his or her finger from the operating section 14 or loosens the forward pressure on the operating section 14, the elastic force of the elastic member 16 urges the ballpoint pen refill 30 backward, causing the ballpoint pen tip 40 to The tip part is retracted from the front end opening 22a. Since the projecting/retracting mechanism 12 that realizes such a projecting/retracting operation is well known, a detailed explanation thereof will be omitted. As an example, as the projecting and retracting mechanism 12, it is possible to use a projecting and retracting mechanism having a rotating cam mechanism.

The ballpoint pen refill 30 is housed in the barrel 20 so as to be retractable. The ballpoint pen refill 30 includes an ink storage cylinder 35 that stores ink, and a ballpoint pen tip 40 attached to the front end of the ink storage cylinder 35. The center axis of the ballpoint pen refill 30 coincides with the center axis A of the ballpoint pen 10. Further, the central axis of the ink storage cylinder 35 and the central axis of the ballpoint pen tip 40 coincide with the central axis A of the ballpoint pen 10. As the ink, any ink that can be used for ballpoint pens may be used without particular limitation. As an example, a thermochromic ink can be used as the ink. The thermochromic ink may be a reversible thermochromic ink. As the reversible thermochromic ink, for example, a heat-erasable reversible thermochromic ink that changes from a colored state to a decolored state by heating and changes from a decolored state to a colored state by cooling can be used.

FIG. 3 is a diagram showing the ballpoint pen tip 40, and is a vertical cross-sectional view showing an enlarged area labeled III in FIG. 2. As shown in FIG. FIG. 4 is a diagram showing the vicinity of the ball 42 of the ballpoint pen tip 40, and is a longitudinal sectional view showing an enlarged region marked IV in FIG. 3. As shown in FIG. FIG. 5 is a diagram showing the hollow tube 90 of the ballpoint pen tip 40 viewed from the front.

The ballpoint pen tip 40 includes a ball 42, a tip body 70, and a hollow tube 90. In the example shown in FIG. 3, the ballpoint pen tip 40 further includes a resilient member 48, an inner cylinder 50, an outer cylinder 60, and a connecting cylinder 80. The ballpoint pen tip 40 has an ink flow path 45. The ink flow path 45 penetrates inside the ballpoint pen tip 40 along the axial direction da. The ink contained in the ink storage cylinder 35 flows toward the ball 42 through the ink flow path 45. In the illustrated example, the ink flow path 45 includes an inner cylinder bore 51, a connecting cylinder bore 81, an ink passage 91, and a ball holding chamber 71, which will be described later.

The inner cylinder 50 is a member that is attached to the front end of the ink storage cylinder 35 and has a substantially cylindrical shape. In particular, the inner cylinder 50 is attached to the ink storage cylinder 35 by inserting the rear end of the inner cylinder 50 into the front end of the ink storage cylinder 35 . The inner cylinder body 50 has an inner cylinder inner hole 51, a locking part 52, an inner cylinder seal part 53, a collar part 54, an inner stage 55, and a regulating part 56. The inner cylinder inner hole 51 is a through hole that penetrates the inner cylinder body 50 in the axial direction da. The inner cylinder bore 51 constitutes a part of the ink flow path 45 . The locking portion 52 is a portion that locks onto a locked portion 62 of the outer cylinder 60. In the illustrated example, the locking portion 52 is a male threaded portion formed on the outer peripheral surface of the front end portion of the inner cylinder 50.

The collar portion 54 protrudes radially outward from the outer circumferential surface of the inner cylinder 50. In the illustrated example, the front end of the ink storage cylinder 35 is in contact with the rear surface of the flange 54 . Further, the rear end of the resilient member 16 is in contact with the front surface of the collar portion 54 .

The outer cylinder 60 is a member that is attached to the front end of the inner cylinder 50 and has a substantially cylindrical shape. The outer cylinder body 60 has a locked part 62 and an outer cylinder seal part 63. The locked portion 62 is a portion to which the locking portion 52 of the inner cylinder 50 locks. In the illustrated example, the locked portion 62 is a female threaded portion formed on the inner peripheral surface of the outer cylinder 60. When the locking portion 52 locks with the locked portion 62, the inner cylinder body 50 and the outer cylinder body 60 are connected to each other. In particular, in the illustrated example, the inner cylinder body 50 and the outer cylinder body 60 are connected to each other by screwing the male threaded part of the locking part 52 into the female thread part of the locked part 62. Ru. In this case, the relative position of the inner cylinder 50 and the outer cylinder 60 in the axial direction da can be adjusted by rotating the inner cylinder 50 and the outer cylinder 60 relative to each other in the circumferential direction. Thereby, the amount of rearward movement of the ball 42, the hollow tube 90, and the connecting tube 80 can be adjusted, as will be described later.

A seal member 47 is arranged between the inner cylinder seal part 53 of the inner cylinder body 50 and the outer cylinder seal part 63 of the outer cylinder body 60. The inner cylinder body seal part 53, the outer cylinder body seal part 63, and the seal member 47 constitute a seal part that airtightly seals between the inner cylinder body 50 and the outer cylinder body 60. The inner cylinder seal portion 53 is an annular groove formed in the outer peripheral surface of the inner cylinder 50 and extends in the circumferential direction. The outer cylinder seal portion 63 is a part of the inner circumferential surface of the outer cylinder 60. In the illustrated example, the seal member 47 is disposed within the annular groove that constitutes the inner cylinder seal portion 53. The seal member 47 is, for example, an O-ring. The O-ring is made of, for example, nitrile rubber. By the seal member 47 coming into close contact with the inner cylinder body seal part 53 and the outer cylinder body seal part 63, the space between the inner cylinder body 50 and the outer cylinder body 60 is airtightly sealed. Thereby, the ink flowing inside the inner cylinder body 50 can be prevented from leaking to the outside through the gap between the inner cylinder body 50 and the outer cylinder body 60. Furthermore, by accommodating the O-ring in the annular groove, even if the outer cylinder 60 is moved relative to the inner cylinder 50 in the axial direction da, the O-ring is prevented from falling off, thereby maintaining an airtight state. Can be easily maintained.

The inner stage 55 is a stepped portion provided in the inner cylindrical inner bore 51 . In the illustrated example, the inner cylinder bore 51 includes a small diameter portion and a large diameter portion located at the position of the small diameter portion and having a larger inner diameter than the small diameter portion. This is a stepped portion provided at the boundary with the large diameter portion. A resilient member 48 is disposed within the inner cylinder bore 51 of the inner cylinder body 50 . The resilient member 48 is, for example, a coil spring. The resilient member 48 is disposed within the large diameter portion of the inner cylinder bore 51, and the rear end of the resilient member 48 is in contact with the inner stage 55. In the illustrated example, the resilient member 48 urges the hollow tube 90 forward via the connecting cylinder 80.

The restriction portion 56 is provided at the front end of the inner cylinder body 50. In the illustrated example, the restriction portion 56 is the front end surface of the inner cylindrical body 50. The regulating portion 56 is configured to be able to come into contact with the connecting tube 80, and when it comes into contact with the connecting tube 80, restricts the rearward movement of the connecting tube 80.

The chip body 70 is a member that holds the ball 42. In the illustrated example, the chip body 70 is attached to the outer cylinder 60. In particular, the tip body 70 is attached to the outer cylinder 60 by inserting the rear end of the chip body 70 into the front end of the outer cylinder 60. The chip body 70 has a ball holding chamber 71 and a front edge 73.

The ball holding chamber 71 has a function of holding the ball 42 , and also has a function of holding ink within the ball holding chamber 71 and making the ink adhere to the ball 42 . The ball holding chamber 71 is constituted by a hole formed from the front end of the chip body 70 toward the rear. In the illustrated example, after the ball 42 is placed in the ball holding chamber 71, the front end edge 73 of the chip body 70 is caulked so as to deform inward (toward the central axis A side). is held in the ball holding chamber 71. The front edge portion 73 protrudes inward at the front end portion of the chip body 70 and can annularly abut against a portion of the front side of the ball 42 . The inner surface of the front edge portion 73 has a truncated conical shape. A portion of the ball 42 protrudes forward from the ball holding chamber 71. Further, another part of the ball 42 may protrude rearward from the ball holding chamber 71.

The connecting cylinder 80 is arranged in front of the inner cylinder body 50 so as to be movable back and forth. The connecting cylinder 80 has a connecting cylinder inner hole 81, a flange portion 83, and an inner stage 85. The connecting cylinder inner hole 81 is a through hole that penetrates the connecting cylinder 80 in the axial direction da. The connecting cylinder inner hole 81 constitutes a part of the ink flow path 45 . The flange portion 83 is a flange-shaped portion that protrudes radially outward from the outer surface of the rear end portion of the connecting tube 80 . The front end of the resilient member 48 disposed within the inner cylinder bore 51 of the inner cylinder body 50 is in contact with the rear surface of the flange portion 83 . The resilient member 48 is disposed in a compressed state between the inner stage 55 of the inner cylinder body 50 and the flange portion 83 of the connecting cylinder 80. The flange portion 83 is configured to be able to abut against the restriction portion 56 of the inner cylinder body 50 . When the connecting tube 80 moves rearward and the flange portion 83 comes into contact with the restricting portion 56, further rearward movement of the connecting tube 80 is restricted.

The hollow tube 90 has a function of supplying the ink that has passed through the connecting cylinder 80 to the ball 42. The hollow tube 90 is a member that is attached to the connecting tube 80 and has a substantially cylindrical shape. In the illustrated example, the hollow tube 90 is attached to the connecting tube 80 by inserting the rear end portion of the hollow tube 90 into the connecting tube 80 from the front. The connecting cylinder 80 has an inner stage 85 on its inner peripheral surface, and the rear end of the hollow tube 90 is in contact with the inner stage 85. The hollow tube 90 has an ink passage 91. The ink passage 91 is a through hole that penetrates the hollow tube 90 in the axial direction da. The ink passage 91 is an ink passage from the connecting cylinder 80 to the ball 42. As best shown in FIGS. 3 to 5, in this embodiment, the ink passage 91 includes a hollow tube inner hole 92 and a groove-shaped portion 93.

The hollow tube inner hole 92 is a cylindrical through hole that extends in the axial direction da along the central axis of the hollow tube 90. The central axis of the hollow tube 90 coincides with the central axis A of the ballpoint pen 10. Therefore, in this specification, the central axis of the hollow tube 90 may be referred to as the central axis A. The groove-shaped portion 93 communicates with the hollow tube inner hole 92, and extends radially from the hollow tube inner hole 92 toward the outside in the radial direction in a cross section perpendicular to the central axis A. The groove-shaped portion 93 extends through the hollow tube 90 in the axial direction da. The hollow tube inner hole 92 and the groove-like portion 93 extend from the front end to the rear end of the hollow tube 90 in the axial direction da. In the example shown in FIGS. 4 and 5, the hollow tube 90 has a plurality of grooves 93. In a cross section perpendicular to the central axis A, the plurality of grooves 93 are preferably arranged at equal angular intervals. In the example shown in FIGS. 4 and 5, the hollow tube 90 has four grooves 93 having an angular spacing of 90 degrees from each other. Note that the present invention is not limited to this, and the hollow tube 90 may have one to three or five or more groove-like portions 93. In the illustrated example, the groove width of the groove-like portion 93 is smaller than the diameter of the hollow tube inner hole 92. As a result, the capillary force applied to the ink within the groove-shaped portion 93 becomes stronger. Therefore, the fluidity of the ink is improved and the ink that has passed through the groove 93 is supplied to the ball 42, so that even if the amount of ink discharged from the gap between the ball 42 and the front edge 73 increases, it is sufficient. Ink is supplied to the ball holding chamber 71.

The hollow tube 90 is made of synthetic resin. As the synthetic resin, for example, polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), polyacetal, polyamide, nylon, etc. can be used. Among them, PEEK is preferably used because it has excellent mechanical strength such as abrasion resistance and impact resistance, and also has good dimensional stability. Hollow tube 90 may be formed by extrusion molding. In this case, the hollow tube inner hole 92, the groove portion 93, and the outer peripheral portion are uniformly formed along the axial direction da, and the hollow tube 90 can be manufactured at low cost. In this embodiment, the hollow tube 90 is entirely made of synthetic resin. As a result, when writing pressure that is higher than necessary is transmitted to the hollow tube 90 via the ball 42, the hollow tube 90 can be elastically deformed within a range that does not undergo plastic deformation. In this embodiment, when the elastic deformation section elastically deforms, for example, the hollow tube 90 is compressed in the axial direction da or bent in the radial direction, thereby making it possible to absorb excessive writing pressure.

A ball receiving seat 95 that comes into contact with and supports the ball 42 is provided at the tip of the hollow tube 90 . In this embodiment, the ball receiving seat 95 has a chamfered shape. In particular, in the illustrated example, the ball receiving seat 95 has a spherical shape that follows the outer shape of the ball 42. This suppresses wear of the ball receiving seat 95 when the ball 42 and the ball receiving seat 95 slide against each other.

The hollow tube 90 is urged forward by the resilient member 48 via the connecting cylinder 80. In this state, the ball receiving seat 95 of the hollow tube 90 is in contact with the ball 42, and the ball 42 is in contact with the front end edge 73 of the chip body 70. At this time, a gap (clearance) is formed between the regulating part 56 of the inner cylinder 50 and the flange part 83 of the connecting cylinder 80 along the axial direction da. When writing with the ballpoint pen 10, when the ball 42 is pushed backward by the pressure of the writing, the ball 42, the hollow tube 90, and the connecting tube 80 resist the elastic force of the resilient member 48. Move backwards. As a result, a gap is formed between the ball 42 and the front edge 73 of the tip body 70, and the ink held in the ball holding chamber 71 flows out onto the writing surface through this gap.

When the ball 42, the hollow tube 90, and the connecting tube 80 move rearward and the flange portion 83 of the connecting tube 80 comes into contact with the regulating portion 56 of the inner cylinder 50, the ball 42, the hollow tube 90, and the connecting tube 80 move backward. Further backward movement of the body is restricted. In this embodiment, the amount of rearward movement of the ball 42, the hollow tube 90, and the connecting tube 80 can be adjusted. As described above, the inner cylinder body 50 and the outer cylinder body 60 have a male screw part that constitutes the locking part 52 of the inner cylinder body 50 and a female screw part that constitutes the locked part 62 of the outer cylinder body 60. are connected by screwing together. Therefore, by rotating the inner cylinder 50 and the outer cylinder 60 relative to each other in the circumferential direction, the relative position of the inner cylinder 50 and the outer cylinder 60 in the axial direction da can be adjusted. When the relative position of the inner cylinder 50 and the outer cylinder 60 in the axial direction da is adjusted so that the inner cylinder 50 is located relatively rearward, the rearward movement of the ball 42, the hollow tube 90, and the connecting cylinder 80 is adjusted. The amount of movement increases. Further, when the relative position of the inner cylinder 50 and the outer cylinder 60 in the axial direction da is adjusted so that the inner cylinder 50 is located relatively forward, the ball 42, the hollow tube 90, and the connecting cylinder 80 The amount of movement to will be smaller.

In a conventional ballpoint pen with a ballpoint tip having a hollow tube placed behind the ball, if the amount of ink supplied from the hollow tube to the ball is not sufficient, the width of the handwriting formed by this ballpoint pen will be It may become smaller or the handwriting may become thinner. Therefore, in such ballpoint pens, it is required to increase the amount of ink supplied from the hollow tube to the ball. The inventors of the present invention have conducted extensive studies on such issues and have found that by setting the dimensions of each part of the hollow tube 90 within a specific range, the amount of ink supplied from the hollow tube 90 to the balls 42 can be improved. It has been found that the amount can be increased. Hereinafter, the dimensions of each part of the hollow tube 90 of this embodiment will be explained.

In the example shown in FIG. 4, the outer diameter D ₉₀ of the hollow tube 90 is greater than the outer diameter D ₄₂ of the ball 42. If the outer diameter D ₉₀ of the hollow tube 90 is less than the outer diameter D ₄₂ of the ball 42, the size of the ink passage 91 of the hollow tube 90 cannot be made sufficiently large. Further, in the illustrated example, the hollow tube 90 is urged forward by the resilient member 48 via the connecting cylinder 80. Thereby, the hollow tube 90 receives a compressive force in the axial direction da. If the size of the ink passage 91 of the hollow tube 90 is increased when the outer diameter D ₉₀ of the hollow tube 90 is less than the outer diameter D ₄₂ of the ball 42, the thickness of the wall of the hollow tube 90 will increase. There is also a risk that the hollow tube 90 may buckle due to the compressive force generated in the hollow tube 90 by the elastic member 48.

On the other hand, in the example shown in FIG. 4, since the outer diameter D ₉₀ of the hollow tube 90 is larger than the outer diameter D ₄₂ of the ball 42, the ink can be The size (cross-sectional area) of the passage 91 can be increased. This makes it possible to effectively improve the degree of freedom in designing the dimensions and shape of the ink passage 91. For example, the degree of freedom in designing the dimensions and shapes of the hollow tube inner hole 92 and the groove-shaped portion 93 included in the ink passage 91 can be improved.

In particular, the outer diameter D ₉₀ of the hollow tube 90 is greater than or equal to 1.05 times and less than or equal to 2.0 times the outer diameter D ₄₂ of the ball 42 . By making the outer diameter D ₉₀ of the hollow tube 90 1.05 times or more the outer diameter D ₄₂ of the ball 42, the size (cross-sectional area) of the ink passage 91 of the hollow tube 90 is made sufficiently large. I can do it. Furthermore, since the outer diameter D ₉₀ of the hollow tube 90 is 2.0 times or less the outer diameter D ₄₂ of the ball 42, the chip body 70 located outside the hollow tube 90 is prevented from increasing in size. be able to. This can prevent the visibility of the tip portion of the tip body 70 from decreasing and making writing difficult. Preferably, the outer diameter D ₉₀ of the hollow tube 90 is at least 1.1 times the outer diameter D ₄₂ of the ball 42 . Further, preferably, the outer diameter D ₉₀ of the hollow tube 90 is 1.5 times or less than the outer diameter D ₄₂ of the ball 42 .

The outer diameter D ₉₀ of the hollow tube 90 may be larger than the inner diameter D ₇₁ of the ball holding chamber 71 . In this case, a more sufficient size (cross-sectional area) of the ink passage 91 can be ensured. This makes it possible to further effectively improve the degree of freedom in designing the dimensions and shape of the ink passage 91.

Preferably, the outer diameter D ₉₀ of the hollow tube 90 may be greater than or equal to 1.01 times and less than or equal to 2.0 times the inner diameter D ₇₁ of the ball holding chamber 71 . Since the outer diameter D ₉₀ of the hollow tube 90 is 1.01 times or more the inner diameter D ₇₁ of the ball holding chamber 71, the size (cross-sectional area) of the ink passage 91 of the hollow tube 90 can be made more sufficient. Can be made larger. Further, since the outer diameter D ₉₀ of the hollow tube 90 is 2.0 times or less than the inner diameter D ₇₁ of the ball holding chamber 71, it is possible to prevent the chip body 70 located outside the hollow tube 90 from becoming large. can be effectively suppressed.

The distance L ₉₄ from the central axis A of the hollow tube 90 to the radially outer end 94 of the grooved portion 93 may be larger than 1/2 of the outer diameter D ₄₂ of the ball 42 . In other words, the distance L ₉₄ from the central axis A of the hollow tube 90 to the radially outer end 94 of the grooved portion 93 may be larger than the radius of the ball 42 . The outer end portion 94 is the radially outermost portion of the groove portion 93 in a cross section perpendicular to the central axis A. In other words, the outer end portion 94 is the part of the groove portion 93 that is furthest away from the center axis A in a cross section perpendicular to the center axis A.

As described above, the groove-shaped portion 93 has the function of improving the fluidity of ink using capillary force and sufficiently supplying ink to the ball holding chamber 71. Since the distance L ₉₄ from the central axis A of the hollow tube 90 to the radially outer end 94 of the grooved portion 93 is greater than 1/2 of the outer diameter D ₄₂ of the ball 42, it is perpendicular to the central axis A. In the cross section, the cross-sectional area of the groove-like portion 93 can be increased without increasing the groove width of the groove-like portion 93. Therefore, the flow rate of ink through the ink passage 91 (grooved portion 93) can be effectively increased.

Preferably, the distance L ₉₄ may be 1.01 times or more and 1.5 times or less of 1/2 of the outer diameter D ₄₂ of the ball 42. By setting the distance L ₉₄ to 1.01 times or more of 1/2 of the outer diameter D ₄₂ of the ball 42, the size (cross-sectional area) of the groove-shaped portion 93 can be further sufficiently increased. Moreover, by setting the distance L ₉₄ to 1.5 times or less of 1/2 of the outer diameter D ₄₂ of the ball 42, it is possible to effectively suppress the chip body 70 from increasing in size.

The distance L ₉₄ may be larger than 1/2 of the inner diameter D ₇₁ of the ball holding chamber 71. In other words, the distance L ₉₄ may be larger than the radius of the ball holding chamber 71. In this case, in the cross section perpendicular to the central axis A, the cross-sectional area of the groove-like part 93 can be further increased without increasing the groove width of the groove-like part 93. Therefore, the flow rate of ink via the ink passage 91 (groove portion 93) can be increased more effectively.

Preferably, the distance L ₉₄ may be 1.01 times or more and 1.3 times or less of 1/2 of the inner diameter D ₇₁ of the ball holding chamber 71. By setting the distance L ₉₄ to 1.01 times or more of 1/2 of the inner diameter D ₇₁ of the ball holding chamber 71, the size (cross-sectional area) of the groove-shaped portion 93 can be further sufficiently increased. Moreover, by setting the distance L ₉₄ to 1.3 times or less of 1/2 of the inner diameter D ₇₁ of the ball holding chamber 71, it is possible to more effectively suppress the chip body 70 from increasing in size.

The inner diameter D ₉₂ of the hollow tube bore 92 may be smaller than the outer diameter D ₄₂ of the ball 42 . Thereby, it is possible to increase the thickness of the wall portion of the hollow tube 90 at a portion where the groove-shaped portion 93 is not formed. Therefore, sufficient strength of the hollow tube 90 can be ensured.

Preferably, the inner diameter D ₉₂ of the hollow tube inner hole 92 may be greater than or equal to 0.2 times and less than or equal to 0.9 times the outer diameter D ₄₂ of the ball 42 . When the inner diameter D ₉₂ of the hollow tube inner hole 92 is 0.2 times or more the outer diameter D ₄₂ of the ball 42, a sufficient cross-sectional area of the hollow tube inner hole 92 and the cross-sectional area of the ink passage 91 can be ensured. Therefore, a sufficient flow rate of ink through the ink passage 91 can be ensured. Further, if the inner diameter D ₉₂ of the hollow tube inner hole 92 is 0.9 times or less than the outer diameter D ₄₂ of the ball 42, the thickness of the wall portion of the hollow tube 90 at the location where the grooved portion 93 is not formed. can be more fully secured.

The ballpoint pen tip 40 of this embodiment includes a ball 42, a tip body 70 having a ball holding chamber 71 for holding the ball 42, and a hollow tube made of synthetic resin that is arranged so as to be able to contact the ball 42 from the rear. 90, and the outer diameter D ₉₀ of the hollow tube 90 is larger than the outer diameter D ₄₂ of the ball 42.

The ballpoint pen refill 30 of this embodiment includes the above-described ballpoint pen tip 40 and an ink storage cylinder 35 that stores ink.

The ballpoint pen 10 of this embodiment includes the above-mentioned ballpoint pen refill 30.

According to such ballpoint pen tip 40, ballpoint pen refill 30, and ballpoint pen 10, since the outer diameter D ₉₀ of the hollow tube 90 is larger than the outer diameter D ₄₂ of the ball 42, the strength of the hollow tube 90 can be sufficiently ensured. Also, the size (cross-sectional area) of the ink passage 91 can be increased. This makes it possible to effectively improve the degree of freedom in designing the dimensions and shape of the ink passage 91. For example, the degree of freedom in designing the dimensions and shapes of the hollow tube inner hole 92 and the groove-shaped portion 93 included in the ink passage 91 can be improved.

In the ballpoint pen tip 40 of this embodiment, the outer diameter D ₉₀ of the hollow tube 90 is greater than or equal to 1.05 times and less than or equal to 2.0 times the outer diameter D ₄₂ of the ball 42 .

According to such a ballpoint pen tip 40, the outer diameter D ₉₀ of the hollow tube 90 is 1.05 times or more the outer diameter D ₄₂ of the ball 42, so that the size of the ink passage 91 of the hollow tube 90 is reduced. (cross-sectional area) can be made sufficiently large. Furthermore, since the outer diameter D ₉₀ of the hollow tube 90 is 2.0 times or less the outer diameter D ₄₂ of the ball 42, the chip body 70 located outside the hollow tube 90 is prevented from increasing in size. be able to. This can prevent the visibility of the tip portion of the tip body 70 from decreasing and making writing difficult.

In the ballpoint pen tip 40 of this embodiment, the outer diameter D ₉₀ of the hollow tube 90 is larger than the inner diameter D ₇₁ of the ball holding chamber 71 .

According to such a ballpoint pen tip 40, a more sufficient size (cross-sectional area) of the ink passage 91 can be ensured. This makes it possible to further effectively improve the degree of freedom in designing the dimensions and shape of the ink passage 91.

In the ballpoint pen tip 40 of the present embodiment, the hollow tube 90 includes a hollow tube inner hole 92 extending in the axial direction da, and a plurality of grooved portions 93 communicating with the hollow tube inner hole 92 and extending radially.

According to such a ballpoint pen tip 40, the grooved portion 93 can improve the fluidity of ink by utilizing capillary force, and can sufficiently supply ink to the ball holding chamber 71.

In the ballpoint pen tip 40 of this embodiment, the distance L ₉₄ from the central axis of the hollow tube 90 to the radially outer end 94 of the grooved portion 93 is larger than 1/2 of the outer diameter D ₄₂ of the ball 42 .

According to such a ballpoint pen tip 40, since the distance L ₉₄ is larger than 1/2 of the outer diameter D ₄₂ of the ball 42, the width of the groove portion 93 is increased in the cross section perpendicular to the central axis A. The cross-sectional area of the groove-shaped portion 93 can be increased without causing any damage. Therefore, the flow rate of ink through the ink passage 91 (grooved portion 93) can be effectively increased.

In the ballpoint pen tip 40 of this embodiment, the distance L ₉₄ from the central axis of the hollow tube 90 to the radially outer end 94 of the grooved portion 93 is smaller than 1/2 of the inner diameter D ₇₁ of the ball holding chamber 71. big.

According to such a ballpoint pen tip 40, in a cross section perpendicular to the central axis A, the cross-sectional area of the groove-like portion 93 can be further increased without increasing the groove width of the groove-like portion 93. Therefore, the flow rate of ink via the ink passage 91 (groove portion 93) can be increased more effectively.

The ballpoint pen tip 40 of this embodiment has a resilient member 48 that urges the hollow tube 90 forward.

According to such a ballpoint pen tip 40, the resilient member 48 urges the hollow tube 90 forward directly or indirectly via the connecting tube 80 or the like. Hollow tube 90 presses ball 42 against front edge 73 of chip body 70 . Therefore, it is possible to suppress ink from leaking from between the ball 42 and the front end edge 73 when not writing.

Modifications of this embodiment will be described with reference to FIGS. 6 to 11. In the following description and the drawings used in the following description, the same reference numerals as those used for corresponding parts in the above-described embodiment are used for parts that can be configured similarly to the above-described embodiment, and there are no overlaps. The explanation will be omitted.

FIG. 6 is a diagram corresponding to FIG. 3, and is a longitudinal cross-sectional view showing a modified example of the ballpoint pen tip 40. FIG. 7 is a diagram showing the vicinity of the ball 42 of the ballpoint pen tip 40 in FIG. 6, and is an enlarged vertical cross-sectional view of the area labeled VII in FIG.

In this modification, the resilient member 48 includes a spring portion 48a and a rod portion 48b that extends forward from the spring portion 48a and contacts the ball 42 from the rear. The spring portion 48a is composed of, for example, a coil spring. The rear end of the rod portion 48b is connected to the spring portion 48a, and the front end of the rod portion 48b abuts the ball 42 from the rear. In the illustrated example, the rear end of the spring portion 48a is in contact with the inner stage 55 of the inner cylinder body 50. In this state, the spring portion 48a is in a compressed state and generates an urging force in the direction in which the spring portion 48a expands. The rod portion 48b transmits the biasing force of the spring portion 48a to the ball 42. As a result, a force that urges the ball 42 forward is always exerted on the ball 42. The diameter of the rod portion 48b is smaller than the inner diameter D ₉₂ of the hollow tube inner hole 92 of the hollow tube 90.

In this modification, the resilient member 48 does not urge the connecting cylinder 80 and the hollow tube 90 forward. The urging force for pressing the ball 42 against the front edge 73 of the chip body 70 is mainly generated by the resilient member 48. By adjusting the relative position of the inner cylinder 50 and the outer cylinder 60 in the axial direction da, the space between the hollow tube 90 (ball receiving seat 95) and the ball 42 and/or the inner The connecting tube 80 and the hollow tube 90 may be positioned such that a gap is formed between the restricting portion 56 of the cylinder 50 and the flange portion 83 of the connecting tube 80. In this case, when the ball 42 moves backward due to the pen pressure during writing, the ball 42 and the hollow tube 90 (ball receiving seat 95) come into contact with each other, and the flange portion 83 of the connecting tube 80 and the inner tube body 50 contact each other. When the ball 42 is in contact with the regulating portion 56, further rearward movement of the ball 42 is regulated. In this state, the connecting tube 80 and the hollow tube 90 receive the pen pressure, and the ball 42 is held by the hollow tube 90 (ball receiving seat 95).

The ballpoint pen tip 40 of this embodiment has a resilient member 48 that urges the ball 42 forward.

According to such a ballpoint pen tip 40, the ball 42 can be urged forward by the resilient member 48 without going through the hollow tube 90, so that the compression generated in the hollow tube 90 due to writing pressure when writing is suppressed. force can be reduced. Thereby, the size (cross-sectional area) of the ink passage 91 of the hollow tube 90 can be further increased. Therefore, it is possible to further improve the degree of freedom in designing the dimensions and shape of the ink passage 91.

FIG. 8 is a longitudinal cross-sectional view showing another modification of the ballpoint pen tip 40. As shown in FIG. FIG. 9 is an enlarged vertical cross-sectional view showing the vicinity of the tip body 70 of the ballpoint pen tip 40 of FIG. 8. As shown in FIG. FIG. 9 shows an enlarged view of the portion marked IX in FIG. Note that in FIG. 9, illustration of the shaft cylinder 20 (front shaft 22) is omitted.

The ballpoint pen tip 40 of this modification includes a ball 42, a tip body 70, a slide member 100, a fixing member 120, and a resilient member 48.

The slide member 100 is disposed inside the chip body 70 and is movable in the axial direction da with respect to the chip body 70. In this modification, the slide member 100 has a function of pressing the ball 42 forward by the elastic force of the elastic member 48. That is, the slide member 100 is arranged so as to be able to press the ball 42 forward. The slide member 100 is disposed inside the chip body 70 and is movable in the axial direction da with respect to the chip body 70. Slide member 100 includes a hollow tube 90. In the example shown in FIGS. 8 and 9, the slide member 100 includes a hollow tube 90 and a holding member 110. The rear end of the hollow tube 90 is press-fitted into the holding member 110 from the front. Hollow tube 90 is fixed to holding member 110.

The holding member 110 has a holding member inner hole 112 and an inner stage 114. The holding member inner hole 112 is a through hole that penetrates the holding member 110 in the axial direction da. The holding member inner hole 112 constitutes a part of the ink flow path 45. The inner stage 114 is a step formed in the holding member inner hole 112. Inner stage 114 includes a generally rearwardly facing surface. In the illustrated example, the front end of the resilient member 48 contacts the inner stage 114 . As a result, the inner stage 114 receives the elastic force of the elastic member 48.

The fixed member 120 is arranged at the rear of the slide member 100. The fixing member 120 is fixed to the chip body 70. The fixing member 120 has an engaging portion 122, a fixing member inner hole 126, and an inner stage 128. The engaging portion 122 is a portion that engages with the chip body 70. In this modification, the engaging portion 122 is a protruding portion that protrudes radially outward from the outer circumferential surface of the fixing member 120. The fixing member 120 is inserted into the chip body 70 from the rear, and the engaging portion 122 is press-fitted into the chip body 70, thereby fixing the fixing member 120 to the chip body 70. Note that in this modification, a notch 124 is formed in the rear portion of the fixing member 120. The notch 124 has a function of facilitating deformation of the rear portion of the fixing member 120 and making it easier to insert the fixing member 120 into the chip body 70.

The fixing member inner hole 126 is a through hole that penetrates the fixing member 120 in the axial direction da. The fixing member inner hole 126 constitutes a part of the ink flow path 45. The inner stage 128 is a step formed in the fixing member inner hole 126. Inner stage 128 includes a generally forward facing surface. In the illustrated example, the rear end of the resilient member 48 contacts the inner stage 128 . Thereby, the inner stage 128 receives the elastic force of the elastic member 48.

The resilient member 48 is arranged between the slide member 100 and the fixed member 120. In particular, the resilient member 48 is arranged in a compressed state between the inner stage 114 of the sliding member 100 and the inner stage 128 of the fixed member 120. Therefore, in this state, the elastic force of the elastic member 48 is generated in the direction in which the elastic member 48 extends. This elastic force causes the slide member 100 to press the ball 42 forward.

A gap G along the axial direction da is formed between the rear end of the slide member 100 and the front end of the fixed member 120. The slide member 100 can move in the axial direction da by the dimension of the gap G along the axial direction da. The dimension of the gap G along the axial direction da can be, for example, 0.003 mm or more and 0.2 mm or less.

In the non-writing state, the ball 42 and the slide member 100 are pressed forward by the resilient force of the resilient member 48. Therefore, in the non-writing state, the ball 42 and the slide member 100 are positioned furthest forward in the movement range of the ball 42 and the slide member 100 along the axial direction da. During writing, when the ball 42 is pressed against a writing surface such as paper, the ball 42 receives writing pressure from the writing surface. This writing pressure causes the ball 42 and the slide member 100 to retreat. When the rear end of the slide member 100 contacts the front end of the fixed member 120, further retreat of the ball 42 and the slide member 100 is prevented. Therefore, the moving distance of the ball 42 and the slide member 100 along the axial direction da is defined by the dimension of the gap G along the axial direction da.

In order to make the dimension of the gap G along the axial direction da a desired dimension, the ballpoint pen tip 40 of this modification can be assembled as follows.

First, the ball 42 is placed inside the chip body 70. Next, the slide member 100 is placed inside the chip body 70. The slide member 100 is inserted into the chip body 70 from the rear of the chip body 70. Next, the ball 42 and the slide member 100 are moved back by a desired dimension with respect to the chip body 70, and the positions of the ball 42 and the slide member 100 with respect to the chip body 70 are fixed. For example, a jig is used to push the ball 42 from the front to the rear by a desired dimension. In this state, the resilient member 48 is inserted into the chip body 70. Note that after the resilient member 48 is inserted into the chip body 70, the ball 42, the slide member 100, and the resilient member 48 may be moved back by a desired dimension with respect to the chip body 70.

Thereafter, the fixing member 120 is inserted into the chip body 70 from the rear of the chip body 70. The fixing member 120 is inserted into the chip body 70 until the front end of the fixing member 120 contacts the rear end of the slide member 100. At this time, the resilient member 48 is compressed between the inner stage 114 of the slide member 100 and the inner stage 128 of the fixed member 120. When the backward pressure on the ball 42 is released in this state, the ball 42 and the slide member 100 move forward due to the resilient force of the resilient member 48, and the ball 42 comes into contact with the front end edge 73. At this time, a gap G having a desired dimension along the axial direction da is formed between the rear end of the slide member 100 and the front end of the fixed member 120.

The ballpoint pen tip 40 of this modification includes a hollow tube 90, a slide member 100 arranged to be able to press the ball 42 forward, and a slide member 100 arranged behind the slide member 100 and fixed to the tip body 70. The resilient member is disposed between the sliding member 100 and the securing member 120, and a gap G is formed between the rear end of the sliding member 100 and the front end of the securing member 120. There is.

According to such a ballpoint pen tip 40, the amount of retreat of the ball 42 when receiving writing pressure is determined by the dimension of the gap G along the axial direction da, regardless of the dimensional accuracy of each component constituting the ballpoint pen tip 40. can be stipulated. Therefore, the amount of retraction of the ball 42 can be precisely defined.

Moreover, according to such a ballpoint pen tip 40, by simply inserting the fixing member 120 into the tip body 70 while pushing the ball 42 by a desired dimension from the front to the rear, the gap G in the axial direction da The dimensions along the line can be set to the desired dimensions. Therefore, the amount of retraction of the ball 42 when receiving pen pressure can be precisely defined by a simple assembly operation.

FIG. 10 is a longitudinal cross-sectional view showing still another modification of the ballpoint pen tip 40. FIG. 11 is an enlarged longitudinal sectional view showing the vicinity of the tip body 70 of the ballpoint pen tip 40 of FIG. 10. FIG. 11 shows an enlarged view of the portion marked with XI in FIG. Note that in FIG. 11, illustration of the shaft tube 20 (front shaft 22) is omitted.

In the example shown in FIGS. 10 and 11, the ballpoint pen tip 40 includes another resilient member 130 in addition to the resilient member 48. In the example shown in FIGS. The resilient member 130 is configured similarly to the resilient member 48 in the modified example described with reference to FIGS. 6 and 7. That is, the resilient member 130 includes a spring portion 130a and a rod portion 130b that extends forward from the spring portion 130a and contacts the ball 42 from the rear. The spring portion 130a is composed of, for example, a coil spring. The rear end of the rod portion 130b is connected to the spring portion 130a, and the front end of the rod portion 130b abuts the ball 42 from the rear. In the illustrated example, the rear end of the spring portion 130a is in contact with the inner stage 55 of the inner cylinder body 50. In this state, the spring portion 130a is in a compressed state and generates an urging force in the direction in which the spring portion 130a expands. The rod portion 130b extends from the spring portion 130a to the ball 42 through the fixing member inner hole 126, the holding member inner hole 112, and the hollow tube inner hole 92. The rod portion 130b transmits the biasing force of the spring portion 130a to the ball 42.

In this modification, the ball 42 receives elastic force from both the elastic member 48 and the other elastic member 130. That is, the ball 42 receives an elastic force that is a combination of the elastic force of the elastic member 48 and the elastic force of the elastic member 130. Therefore, the elastic force of the elastic member 48 may be smaller than the elastic force of the elastic member 48 in the modified example described with reference to FIGS. 8 and 9. Further, in this modification, the resilient member 48 may be omitted. In this case, since the hollow tube 90 is not pressed against the ball 42, wear of the front end portion of the hollow tube 90 can be suppressed.

10 Ballpoint pen 12 Retractable mechanism 14 Operating section 16 Resilient member 20 Barrel 22 Front shaft 22a Front end opening 22b Inner stage 24 Grip member 26 Rear shaft 28 Clip 30 Ballpoint pen refill 35 Ink storage cylinder 40 Ballpoint pen tip 42 Ball 45 Ink channel 47 Seal member 48 Resilient member 48a Spring part 48b Rod part 50 Inner cylinder body 51 Inner cylinder bore 52 Locking part 53 Inner cylinder seal part 54 Flange part 55 Inner stage 56 Regulating part 60 Outer cylinder body 62 Locked part 63 Outer cylinder seal part 70 Chip body 71 Ball holding chamber 73 Front edge part 80 Connecting cylinder 81 Connecting cylinder inner hole 83 Flange part 85 Inner stage 90 Hollow tube 91 Ink passage 92 Hollow tube inner hole 93 Groove part 94 Outer end 95 Ball receiving seat 100 Slide member 110 Holding member 112 Holding member inner hole 114 Inner stage 120 Fixed member 122 Engagement part 124 Notch 126 Fixed member inner hole 128 Inner stage 130 Other resilient member 130a Spring part 130b Rod part A Center axis line

Claims (11)

ball and
a chip body having a ball holding chamber that holds the ball;
A hollow tube made of synthetic resin is arranged so as to be able to contact the ball from the rear,
The outer diameter of the hollow tube is larger than the outer diameter of the ball. The ballpoint pen tip according to claim 1, wherein the outer diameter of the hollow tube is 1.05 times or more and 2.0 times or less the outer diameter of the ball. The ballpoint pen tip according to claim 1, wherein the outer diameter of the hollow tube is larger than the inner diameter of the ball holding chamber. The ballpoint pen tip according to claim 1, wherein the hollow tube includes a hollow tube inner hole extending in the axial direction, and a plurality of groove-like portions communicating with the hollow tube inner hole and extending radially. The ballpoint pen tip according to claim 4, wherein the distance from the central axis of the hollow tube to the radially outer end of the grooved portion is greater than 1/2 of the outer diameter of the ball. The ballpoint pen tip according to claim 4, wherein the distance from the central axis of the hollow tube to the radially outer end of the grooved portion is greater than 1/2 of the inner diameter of the ball holding chamber. The ballpoint pen tip according to claim 1, further comprising a resilient member that urges the hollow tube forward. a sliding member that includes the hollow tube and is movable in the axial direction;
further comprising a fixing member disposed behind the slide member and fixed to the chip body,
The elastic member is arranged between the slide member and the fixed member,
The ballpoint pen tip according to claim 7, wherein a gap is formed between the rear end of the slide member and the front end of the fixed member. The ballpoint pen tip according to claim 1, further comprising a resilient member that urges the ball forward. A ballpoint pen refill comprising the ballpoint pen tip according to any one of claims 1 to 9 and an ink storage cylinder that stores ink. A ballpoint pen comprising the ballpoint pen refill according to claim 10.