JP7493442B2 - Pressurized writing implement - Google Patents

Description

The present invention relates to a pressure-type writing instrument.

In writing implements such as ballpoint pens, there are known pressurized writing implements that can apply pressure to the ink filled inside. Patent Document 1 discloses a pressurized writing implement that includes a barrel that can accommodate a refill filled with ink, a pressurizing mechanism that applies pressure to the ink as the refill retracts, and a pressurizing force adjustment mechanism that adjusts the pressure. The pressurizing mechanism includes a cylindrical body, a stopper that is attached to the cylindrical body so as to be movable back and forth, an elastic member that is press-fitted into the inner periphery of the cylindrical body and detachably attached to the rear end of the refill, and a pressurized space that is formed inside the elastic member and communicates with the rear inner hole of the refill.

In this pressurized writing instrument, when writing pressure is applied to the front end of the refill and the refill retracts, the cylindrical body retracts together with the elastic member. Then, when the rear end of the elastic member abuts against the front end face of the stopper, the air hole is blocked by the front end face and the pressurized space is sealed. Furthermore, when the refill retracts and the cylindrical body retracts, the elastic member elastically deforms, compressing the pressurized space and applying pressure to the rear end of the ink in the refill via the ink follower. In other words, as the refill retracts, pressure is applied to the rear end of the ink by the pressure mechanism.

International Publication No. 2019/026808

Depending on the composition and viscosity of the ink, the structure of the pen tip, etc., it may be necessary to generate a relatively small pressure force using the pressure mechanism. In conventional pressure-type writing instruments, the volume of the pressure space formed inside the elastic member is small, so a small stroke of the stopper generates a relatively large pressure force. In such pressure-type writing instruments, changing the stroke of the stopper by only a small distance can cause a large change in pressure force. Therefore, it has been difficult to stably generate a small pressure force.

The present invention was made with these points in mind, and aims to stably generate pressure in a pressure-type writing instrument.

The pressure-type writing instrument according to the present invention comprises:
A shaft cylinder,
a refill disposed within the barrel and having an ink reservoir filled with ink;
a pressure mechanism for applying pressure to the rear end of the ink;
the pressure mechanism includes an elastic member and a pressing member located behind the elastic member,
The elastic member has a rear member having an opening, a side member extending forward from a peripheral edge of the rear member, and a first internal space surrounded by the rear member and the side member,
The area of a cross section of the first internal space perpendicular to the central axis of the barrel decreases toward the rear,
When the elastic member moves rearward, the front end of the pressing member abuts against the elastic member, sealing the opening, thereby forming a pressurized chamber including the first internal space, and the volume of the pressurized chamber is reduced by deforming at least a portion of the elastic member.

In the pressure-type writing instrument according to the present invention,
In a cross section including the central axis, the side members may be curved so as to protrude in a direction away from the central axis.

In the pressure-type writing instrument according to the present invention,
The rear member includes an inner region including a contour of the opening and surrounding the opening, and an outer region positioned radially outward relative to the inner region,
The thickness of the inner region may be greater than the thickness of the outer region.

In the pressure-type writing instrument according to the present invention,
The opening may not allow the front end of the pressing member to be inserted therethrough.

In the pressure-type writing instrument according to the present invention,
The device may further include a spacer member disposed in front of the elastic member and having a second internal space communicating with the first internal space.

In the pressure-type writing instrument according to the present invention,
The ink container further includes a tail plug attached to a rear end of the ink container.
At least a portion of the tail plug which comes into contact with the ink reservoir may be made of an elastic material.

According to the present invention, it is possible to stably generate pressure in a pressure-applied writing instrument.

FIG. 1 is a vertical cross-sectional view showing a pressure-type writing instrument according to one embodiment of the present invention, and shows the pressure-type writing instrument in a state in which a ballpoint pen tip is retracted. FIG. 2 is a vertical cross-sectional view showing the pressure type writing instrument of FIG. 1 in a state where the ballpoint tip is protruded. FIG. 3 is an enlarged view of the pressure mechanism of the pressure-type writing instrument of FIG. FIG. 4 is an enlarged view of the elastic member of the pressure mechanism. FIG. 5 is a diagram for explaining the operation of the pressure mechanism. FIG. 6 is a diagram for explaining the operation of the pressure mechanism.

One embodiment of the present invention will now be described with reference to the drawings. Note that in the drawings attached to this specification, the scale and aspect ratios have been appropriately altered and exaggerated from those of the actual objects for the sake of ease of illustration and understanding.

In addition, terms used in this specification that specify shapes, geometric conditions, and the degree of those conditions, such as "parallel," "orthogonal," and "same," as well as values of lengths and angles, are to be interpreted without being bound by strict meanings, but rather to include the range in which similar functions can be expected.

In this specification, the direction in which the central axis A of the writing implement extends (longitudinal direction, up and down direction in a longitudinal cross section) is referred to as the axial direction da, the direction perpendicular to the axial direction da is referred to as the radial direction, and the direction along the circumference around the central axis A is referred to as the circumferential direction. Additionally, along the axial direction da, the side that is close to the surface being written on, such as a piece of paper, when writing is referred to as the front, and the side that is away from the surface being written on is referred to as the rear. In other words, the side facing the pen tip is the front, and the side opposite the pen tip is the rear.

Figure 1 is a vertical cross-sectional view of a pressure-sensitive writing instrument 10 according to one embodiment of the present invention, showing the pressure-sensitive writing instrument 10 in a retracted state, and Figure 2 is a vertical cross-sectional view of the pressure-sensitive writing instrument 10 in a protruding state.

In this embodiment, an example will be described in which the pressure-type writing instrument 10 is a ballpoint pen. The pressure-type writing instrument 10 includes a barrel 20, a refill 30, and a pressure mechanism 50. In the pressure-type writing instrument 10 of this embodiment, the pressure mechanism 50 applies pressure to the rear end surface of the ink 31 contained in the refill 30, thereby increasing the amount of ink 31 ejected from the pen tip of the pressure-type writing instrument 10. This increases the density and width of the handwriting formed using the pressure-type writing instrument 10.

The barrel 20 has a front barrel 21, a grip member 25 arranged around the outer periphery of the front barrel 21, and a rear barrel 26 connected to the rear end of the front barrel 21. The front barrel 21 is a member having a substantially cylindrical shape, and has a front end opening 23 at its front end through which the tip of the ballpoint pen tip 34 described later can be inserted and removed. The grip member 25 is formed of an elastic material such as rubber or elastomer, and is intended to be grasped by the user's fingers when writing with the pressure-type writing instrument 10. The rear barrel 26 is a member having a substantially cylindrical shape arranged behind the front barrel 21. The front end of the rear barrel 26 is attached to the rear end of the front barrel 21, so that the rear barrel 26 is connected to the front barrel 21. As an example, the rear barrel 26 is connected to the front barrel 21 by screwing a female screw portion formed on the inner periphery of the front end of the rear barrel 26 into a male screw portion formed on the outer periphery of the rear end of the front barrel 21. The rear shaft 26 has a rear end opening 28 at its rear end into which a knock body 41 (described later) is inserted so as to be movable back and forth. A receiving member 29 is fixed to an inner surface 27 of the rear shaft 26. The rearward surface of the receiving member 29 receives the elastic force of an elastic member 47 (described later). The receiving member 29 may be provided integrally with the rear shaft 26. That is, the receiving member 29 may be a protrusion that protrudes inward from the inner surface 27 of the rear shaft 26. A cam groove is formed on the inner surface 27 at the rear of the rear shaft 26, which can engage with a cam portion formed on the knock body 41 and the rotating cam member 43 (described later). Such a front shaft 21 and rear shaft 26 are formed of, for example, resin.

The refill 30 is disposed within the barrel 20. In this embodiment, the refill 30 includes an ink storage tube 33 that stores ink 31 and an ink follower 32, and a ballpoint pen tip 34 attached to the front end of the ink storage tube 33.

As the ink 31, any ink that can be used in a writing instrument, such as an oil-based ink, a water-based ink, a gel ink, or a thermochromic ink, can be used without any particular restrictions. Among these inks, low-viscosity inks with an ink viscosity of 5000 (mPa·s) or less at a shear rate of 1.92 (sec ⁻¹ ) in a 20° C. environment are suitable for use in the writing instrument of this embodiment, since the ink discharge amount increases or decreases greatly due to pressure application, and the density, width, etc. of the handwriting change greatly due to pressure application. As an example, a thermochromic ink can be used as the ink 31. The thermochromic ink may be a reversible thermochromic ink. As the reversible thermochromic ink, various reversible thermochromic inks may be used alone or in combination, such as a thermal decolorization type that changes from a colored state to a decolored state by heating and changes from the decolored state to a colored state by cooling, a thermal coloring type that changes from a decolored state to a colored state by heating and changes from the colored state to the decolored state by cooling, or a color memory retention type that exhibits a specific color in a specific temperature range and changes color depending on temperature. For example, an ink containing a reversible thermochromic microencapsulated pigment may be used as the reversible thermochromic ink.

The ink follower 32 is provided to prevent the ink 31 from leaking out of the ink storage tube 33 and to suppress drying of the ink 31. The ink follower 32 is disposed in contact with the rear end of the ink 31. When the ink 31 is consumed and the rear end of the ink 31 moves forward, the ink follower 32 moves forward following the rear end of the ink 31. For example, a grease-like material can be used as such an ink follower 32.

The ink storage cylinder 33 is a member having a cylindrical shape extending in the front-rear direction. The ink storage cylinder 33 stores the ink 31 and the ink follower 32 inside. The ink storage cylinder 33 is formed, for example, from resin.

The ballpoint pen tip 34 includes a tip holder 35, a tip body 36, a ball 37, and a resilient member 38. The tip holder 35 is a member that holds the tip body 36. The rear end of the tip holder 35 is inserted into the front end of the ink storage tube 33, and the tip holder 35 is attached to the ink storage tube 33. Inside the tip holder 35, a through hole is provided that extends in the front-rear direction and guides the ink 31 in the ink storage tube 33 to the tip body 36. The ball 37 is held in a ball holding chamber formed in the front end of the tip body 36. Inside the tip body 36, a through hole is provided that extends in the front-rear direction and guides the ink 31 from the tip holder 35 to the ball 37. The resilient member 38 is arranged in a compressed state inside the through hole of the tip body 36 and urges the ball 37 forward. The force of the resilient member 38 presses the ball 37 against the front end opening of the ball holding chamber of the tip body 36. This makes it possible to prevent the ink 31 from leaking out from the gap between the ball 37 and the front end opening of the ball holding chamber when the ball 37 is not pressed against the writing surface. The resilient member 38 can be, for example, a coil spring.

The pressure-type writing instrument 10 of this embodiment further includes a retraction mechanism. The retraction mechanism is a mechanism for alternately switching the pressure-type writing instrument 10 between a protruding state in which the tip of the ballpoint pen tip 34 protrudes from the front end opening 23 of the front shaft 21 and a retracted state in which the tip of the ballpoint pen tip 34 retracts from the front end opening 23. The retraction mechanism includes a knock body 41, a rotating cam member 43, and a resilient member 47. The knock body 41 is a substantially cylindrical member with a closed rear end. The knock body 41 has a cam portion provided at the front end and a cam portion provided on the outer surface and capable of engaging with a cam groove formed on the inner surface 27 of the rear shaft 26. The knock body 41 is a member that the user touches when performing the retraction operation of the pen tip in the pressure-type writing instrument 10. The rotating cam member 43 is a substantially cylindrical member with a closed rear end, and is rotatable around the central axis A. . The rotating cam member 43 has a cam portion that can be engaged with a cam portion provided at the front end of the knock body 41, and a cam portion that is provided on the outer surface and can be engaged with a cam groove formed on the inner surface 27 of the rear shaft 26. The rotating cam member 43 has a receiving portion 45, which is a surface facing forward, on the outer surface. A resilient member 47 is disposed between the receiving member 29 fixed to the inner surface 27 of the rear shaft 26 and the receiving portion 45 of the rotating cam member 43. The resilient member 47 may be disposed in a compressed state between the receiving member 29 and the receiving portion 45. The receiving portion 45 cooperates with the receiving member 29 to receive the resilient force of the resilient member 47. For example, a coil spring can be used as the resilient member 47. The resilient member 47 can be a retractable mechanism that causes the tip of the ballpoint pen tip 34 to protrude and retract from the front end opening 23 of the front shaft 21, and therefore a detailed description thereof will be omitted. As an example, the retraction mechanism of this embodiment can be a mechanism similar to the retraction mechanism disclosed in JP 11-78361 A, which has a cam groove, a rotating cam, and a knock body formed on the inner surface of the barrel.

Next, the pressure mechanism 50 will be described. FIG. 3 is an enlarged view of the pressure mechanism 50 of the pressure-type writing instrument 10 of FIG. 2. In the example shown in FIG. 3, the pressure mechanism 50 includes a resilient member 55, a receiving member 56, a pressing member 60, a guide member 70, an elastic member 80, and a spacer member 90.

The resilient member 55 is a member that generates a resilient force that biases the refill 30 forward against the compressive force received from the refill 30 when the refill 30 moves rearward. For example, a coil spring can be used as the resilient member 55.

The receiving member 56 is a member that receives the elastic force of the elastic member 55. The rear end of the receiving member 56 is inserted inside the front end of the rotating cam member 43 and is fixed to the rotating cam member 43. The receiving member 56 has a receiving portion 57 that receives the elastic force of the elastic member 55. The receiving portion 57 is a surface of the receiving member 56 that faces forward. The receiving member 56 has a protruding portion 58 that protrudes forward at the front end. The rear end of the elastic member 55 is disposed radially inside the protruding portion 58. The protruding portion 58 restricts the radial movement of the elastic member 55. A claw portion 59 is formed on the inner surface of the protruding portion 58.

The pressing member 60 is a member that applies a pressing force to the elastic member 80. The front end 61 of the pressing member 60 has a function of sealing the opening 83 of the elastic member 80 when it abuts against the opening 83. In this embodiment, the front end 61 is configured as a plane perpendicular to the central axis A. Not limited to this, the front end 61 can have any shape as long as it can seal the opening 83 of the elastic member 80 when it abuts against the opening 83. The pressing member 60 includes a small diameter portion 63, a medium diameter portion 65 located behind the small diameter portion 63, and a large diameter portion 67 located behind the medium diameter portion 65. The outer diameter of the medium diameter portion 65 is larger than the outer diameter of the small diameter portion 63, and the outer diameter of the large diameter portion 67 is larger than the outer diameter of the medium diameter portion 65. The pressing member 60 has a shoulder portion 69 on the outer surface between the small diameter portion 63 and the medium diameter portion 65. The shoulder portion 69 is a surface of the pressing member 60 facing forward. The inside of the pressing member 60 has a hollow portion, which is closed at the front end of the pressing member 60 and opens at the rear end of the pressing member 60. In the pressing member 60 of this embodiment, the insides of the medium diameter portion 65 and the large diameter portion 67 have hollow portions. However, this is not limited to this, and the insides of the small diameter portion 63, the medium diameter portion 65, and the large diameter portion 67 may also have hollow portions.

The rear end of the pressing member 60 is inserted into the rotating cam member 43 from the front of the rotating cam member 43. The rear end of the pressing member 60 abuts against a step formed inside the rotating cam member 43, thereby restricting the rearward movement of the pressing member 60 relative to the rotating cam member 43. In this embodiment, the rear end (large diameter portion 67) of the pressing member 60 is fitted into the rotating cam member 43, thereby restricting the axial and circumferential movement of the pressing member 60 relative to the rotating cam member 43. In other words, the pressing member 60 rotates integrally with the rotating cam member 43 as the rotating cam member 43 rotates about the central axis A.

The guide member 70 is a member that guides the pressing member 60 and the elastic member 80 when the pressing member 60 and the elastic member 80 move relative to each other in the front-rear direction. The guide member 70 of this embodiment includes a rear portion 71 that has a substantially cylindrical shape and is located on the rear side, and a front portion 72 that has a substantially cylindrical shape with a larger diameter than the rear portion 71 and is located in front of the rear portion 71. The guide member 70 has a through hole 73 inside the rear portion 71 through which the front end portion (small diameter portion 63) of the pressing member 60 can pass. The through hole 73 is a hole surrounded by the tip of a protrusion that protrudes inward from the inner surface of the rear portion 71. The rearward surface of this protrusion is an abutment portion 74 that abuts against the shoulder portion 69 of the pressing member 60. When the guide member 70 moves rearward relative to the pressing member 60, the abutment portion 74 abuts against the shoulder portion 69, thereby restricting further rearward movement of the guide member 70.

The guide member 70 has a guide portion 75 inside the rear portion 71 that guides the medium diameter portion 65 of the pressing member 60. The guide portion 75 is allowed to move along the axial direction da relative to the medium diameter portion 65 of the pressing member 60, and is restricted from moving in the radial direction. A claw portion 76 that can engage with the claw portion 59 of the receiving member 56 is formed on the outer surface of the rear end of the guide member 70. The claw portion 76 abuts against the claw portion 59 from the rear, restricting the forward movement of the guide member 70 relative to the receiving member 56. On the other hand, the claw portion 76 is allowed to move rearward away from the claw portion 59. Therefore, from a state in which the claw portion 76 abuts against the claw portion 59, the guide member 70 can move rearward relative to the receiving member 56.

A receiving portion 77 is formed on the outer surface of the step formed between the rear portion 71 and the front portion 72 of the guide member 70. The receiving portion 77 is a surface facing rearward on the outer surface of the guide member 70. A resilient member 55 is disposed between the receiving portion 57 of the receiving member 56 and the receiving portion 77 of the guide member 70. The receiving portion 77 cooperates with the receiving portion 57 to receive the resilient force of the resilient member 55.

The front end of the guide member 70 engages with the outer surface of the rear end of the spacer member 90, thereby fixing the spacer member 90 to the guide member 70. An inner step 78 is formed on the inner surface of the front portion 72 of the guide member 70. The peripheral edge of the front end of the elastic member 80 is sandwiched between this inner step 78 and the spacer member 90.

Figure 4 is an enlarged view of the elastic member 80. The elastic member 80 is made of an elastic material such as rubber or elastomer, and has a first internal space S1 inside. The elastic member 80 is disposed inside the front part 72 of the guide member 70. The elastic member 80 includes a rear member 81 and a side member 85. When the rear member 81 is not subjected to a pressing force from the pressing member 60, the rear member 81 extends in a direction perpendicular to the central axis A and has an opening 83 at the center. The opening 83 penetrates the rear member 81 in the front-rear direction. The side member 85 extends forward from the periphery of the rear member 81. The elastic member 80 has a cup-like shape as a whole due to the rear member 81 and the side member 85. The first internal space S1 is a space surrounded by the rear member 81 and the side member 85.

In a cross section including the central axis A (cross section shown in FIG. 4), the side member 85 of the elastic member 80 extends closer to the central axis A toward the rear. As a result, the area of the cross section of the first internal space S1 perpendicular to the central axis A decreases toward the rear. In the example shown in FIG. 4, the area of the cross section of the first internal space S1 perpendicular to the central axis A gradually decreases. In particular, the area of the cross section of the first internal space S1 perpendicular to the central axis A changes only to decrease toward the rear. That is, the area of the cross section of the first internal space S1 perpendicular to the central axis A continues to change continuously to become smaller toward the rear. However, this is not limited to this, and the area of the cross section of the first internal space S1 perpendicular to the central axis A may change to become smaller in stages toward the rear.

Since the pressure mechanism has such an elastic member 80, the capacity of the pressure chamber C can be made larger than that of pressure-type writing instruments of the prior art. When the capacity of the pressure chamber C is increased, the change in pressure force becomes small even if the elastic member 80 is deformed relatively greatly. Therefore, it becomes easier to make minute changes in pressure force. This makes it possible to stably generate pressure force in the pressure-type writing instrument 10. In particular, it is possible to stably generate small pressure force in the pressure-type writing instrument 10.

In addition, because the pressing force required to deform the elastic member 80 is reduced, the resilient force required to release the deformation of the elastic member 80 can be reduced. In other words, the resilient force of the resilient member 55 can be reduced. This reduces the pressing force required to properly exert pressure on the ink when the user presses the pen tip against the writing surface to write. Therefore, the user can properly press the rear end of the ink 31 by simply pressing the pen tip against the writing surface with a light force.

In a cross section including the central axis A (cross section shown in FIG. 4), the side members 85 of the elastic member 80 are curved so as to protrude in a direction away from the central axis A. In addition, the rate of reduction in the area of the cross section of the first internal space S1 perpendicular to the central axis A increases toward the rear. Here, the rate of reduction in the cross section area is the difference in area between two cross sections separated by a certain length (e.g., 1 mm) along the axial direction da.

Since the side members 85 of the elastic member 80 have such a shape, the side members 85 of the elastic member 80 can be deformed more easily. Therefore, the pressure-type writing instrument 10 can generate a pressure force more stably. In particular, the pressure-type writing instrument 10 can generate a small pressure force more stably.

In addition, the pressing force required to deform the elastic member 80 can be further reduced. In other words, the resilience force required to release the deformation of the elastic member 80 can be further reduced. This further reduces the pressing force required to properly exert pressure on the ink when the user presses the pen tip against the writing surface to write.

The rear member 81 includes an inner region R1 and an outer region R2. The inner region R1 is a region that includes the outline of the opening 83 and surrounds the opening 83 when viewed from the axial direction da. The outer region R2 is a region that is located radially outward from the inner region R1 and surrounds the inner region R1 when viewed from the axial direction da. The thickness T1 of the inner region R1 along the axial direction da is greater than the thickness T2 of the outer region R2 along the axial direction da.

Since the inner region R1 of the rear member 81 has such a thickness T1, when the elastic member 80 deforms, the amount of deformation of the rear member 81 in the inner region R1 located near the opening 83 can be made smaller than the amount of deformation of the rear member 81 in the outer region R2. This makes it possible to prevent a gap from being generated between the inner region R1 and the front end 61 of the pressing member 60 due to deformation of the elastic member 80. Therefore, the sealing ability of the opening 83 by the pressing member 60 can be effectively improved.

In this embodiment, the opening 83 of the rear member 81 has a shape and/or dimensions that do not allow the front end 61 of the pressing member 60 to be inserted therein. For example, the radial inner diameter of the opening 83 is smaller than the radial outer diameter of the front end 61 of the pressing member 60. This makes it possible to prevent the opening 83 from being damaged by being scraped by the pressing member 60.

The spacer member 90 is a member disposed in front of the elastic member 80, and has a second internal space S2 inside that communicates with the first internal space S1 of the elastic member 80. In particular, the spacer member 90 is disposed between the elastic member 80 and the refill 30, and has the function of ensuring sufficient volume for the pressurized chamber C described below. An outer step 92 is formed on the outer surface of the rear end of the spacer member 90. The front end peripheral edge of the elastic member 80 is sandwiched between the outer step 92 and the inner step 78 of the guide member 70. This fixes the elastic member 80 between the guide member 70 and the spacer member 90.

By using such a spacer member 90, the capacity of the pressure chamber C can be further increased. Therefore, in the pressure-type writing instrument 10, it becomes possible to generate a pressure force more stably. In particular, it becomes possible to generate a small pressure force more stably.

The pressure-type writing instrument 10 of this embodiment further includes a refill holding member 51 and a tail plug 53. The refill holding member 51 is a member that holds the refill 30. The refill holding member 51 is engaged with the spacer member 90. In particular, the rear end of the refill holding member 51 is inserted into the front end of the spacer member 90 and fixed to the spacer member 90. The rear end of the refill 30 is inserted into the front end of the refill holding member 51 and fixed to the refill holding member 51. This allows the refill 30 to move back and forth together with the guide member 70, the elastic member 80, and the spacer member 90.

The tail plug 53 is disposed inside the spacer member 90 and the refill holding member 51. In the example shown in FIG. 3, a protrusion provided on the outer periphery of the rear end of the tail plug 53 is located between the protrusion protruding inward from the inner surface of the refill holding member 51 and the spacer member 90. This fixes the tail plug 53 to the spacer member 90 and the refill holding member 51. When the rear end of the refill 30 is inserted into the refill holding member 51, the front end of the tail plug 53 is attached to the rear end of the ink holding tube 33. At least the part of the tail plug 53 that contacts the ink holding tube 33 is formed of an elastic body so as to be in close contact with the ink holding tube 33. In particular, in this embodiment, the front end of the tail plug 53 is inserted into the rear end of the ink holding tube 33. In this case, at least the part of the tail plug 53 that contacts the inner surface of the ink holding tube 33 is formed of an elastic body. The outer diameter of the elastic body at the front end of the tail plug 53 when not inserted into the rear end of the ink reservoir 33 is larger than the inner diameter at the rear end of the ink reservoir 33. Such a tail plug 53 makes it possible to prevent air from leaking between the ink reservoir 33 and the tail plug 53. Preferably, the entire tail plug 53 is made of an elastic body. In this case, it is also possible to prevent air from leaking between the spacer member 90 and the refill holding member 51. The tail plug 53 has a through hole that penetrates the tail plug 53 in the front-rear direction.

The pen tip extension and retraction operation of the pressure-type writing instrument 10 will be described with reference to Figures 1 and 2. Figure 1 shows the pressure-type writing instrument 10 with the ballpoint pen tip 34 retracted, and Figure 2 shows the pressure-type writing instrument 10 with the ballpoint pen tip 34 protruding.

In the recessed state shown in FIG. 1, the rotating cam member 43 is biased backward by the resilient force of the resilient member 47, so that the tip of the ballpoint pen tip 34 is recessed from the front end opening 23. When the user pushes the knock body 41 forward with his finger to slide it, the rotating cam member 43 and the receiving member 56 move forward together with the knock body 41. As a result, the resilient member 55 pushes the guide member 70 forward, and the guide member 70, the elastic member 80, the spacer member 90, the refill holding member 51, the tail plug 53 and the refill 30 move forward. As a result, the tip of the ballpoint pen tip 34 protrudes forward from the front end opening 23, resulting in the protruding state shown in FIG. 2. Even if the user releases his finger from the knock body 41, the refill 30 maintains the state in which the tip of the ballpoint pen tip 34 protrudes forward from the front end opening 23. When the user presses and slides the knock body 41 forward with his/her finger again in the protruding state, the refill 30 moves forward by a small distance. When the user removes his/her finger from the knock body 41 or releases the forward pressure on the knock body 41, the resilience of the resilient member 47 urges the refill 30 backward, and the tip of the ballpoint pen tip 34 retracts from the front end opening 23, resulting in the retracted state shown in FIG. 1.

Next, the method of applying pressure by the pressure mechanism 50 will be described with reference to Figures 2, 3, 5, and 6. In the pressurized writing instrument 10 in the protruding state shown in Figures 2 and 3, when a user presses the pen tip, more specifically the ball 37 of the refill 30, against a writing surface such as paper for writing, the refill 30 is pushed backward relative to the barrel 20, and the guide member 70 moves backward against the elastic force of the elastic member 55 together with the refill 30, the refill holding member 51, the spacer member 90, and the elastic member 80. Then, as shown in Figure 5, the rear member 81 of the elastic member 80 comes into contact with the front end 61 of the pressing member 60, and the opening 83 of the elastic member 80 is sealed by the front end 61 of the pressing member 60. At this time, a pressurized chamber C sealed by the front end 61 of the pressing member 60 is formed. The pressure chamber C includes the first internal space S1 of the elastic member 80, the second internal space S2 of the spacer member 90, the space inside the through hole of the tail plug 53, and the space behind the ink follower 32 in the ink reservoir tube 33.

When the refill 30 moves further backward, as shown in FIG. 6, the guide member 70 moves backward and approaches the receiving member 56 while compressing the resilient member 55. At this time, the elastic member 80 is pressed against the pressing member 60, and a pressing force from the front end 61 of the pressing member 60 acts on the elastic member 80. At least a part of the elastic member 80 is deformed by the pressing force from the pressing member 60. In particular, in this embodiment, the entire elastic member 80 is deformed by the pressing force from the pressing member 60. As a result, the volume of the first internal space S1 of the elastic member 80 is reduced. Therefore, the entire volume of the pressurized chamber C including the first internal space S1 is also reduced. At this time, since the pressurized chamber C is sealed by the front end 61 of the pressing member 60, the air inside the pressurized chamber C is pressurized. In other words, the pressure inside the pressurized chamber C increases. The rear end of the ink 31 is pressed through the ink follower 32 by the increased pressure inside the pressurized chamber C. Therefore, the amount of ink 31 ejected from the pen tip of the pressure-type writing instrument 10 increases. In addition, the contact portion 74 of the guide member 70 contacts the shoulder portion of the pressing member 60, restricting further rearward movement of the guide member 70. In other words, further deformation of the elastic member 80 is suppressed.

When the user releases the pen tip from the writing surface, the refill 30, the refill holding member 51, the spacer member 90, the elastic member 80, and the guide member 70 move forward due to the elastic force of the elastic member 55. At this time, the elastic member 80 moves forward, and the deformation of the elastic member 80 caused by the pressing force from the pressing member 60 is released. Therefore, the volume of the first internal space S1 of the elastic member 80 increases. In particular, the volume of the first internal space S1 of the elastic member 80 becomes the same as the volume of the first internal space S1 of the elastic member 80 before pressurization. As a result, the internal volume of the pressurizing chamber C also becomes approximately the same as the internal volume of the pressurizing chamber C before pressurization. Strictly speaking, the internal volume of the pressurizing chamber C increases by an amount equivalent to the amount of ink 31 consumed while the inside of the pressurizing chamber C is pressurized, but usually, the amount of ink 31 consumed while the inside of the pressurizing chamber C is pressurized is sufficiently smaller than the internal volume of the pressurizing chamber C before pressurization. As a result, the pressure on the rear end of the ink 31 is released.

When the elastic member 80 moves further forward, it moves away from the front end 61 of the pressing member 60, the opening 83 of the elastic member 80 is unsealed, and the first internal space S1 of the elastic member 80 is connected to the atmosphere. This prevents the ink 31 from leaking out from the pen tip when the ball 37 is not pressed against the writing surface. More specifically, when the ball 37 is not pressed against the writing surface, the ink 31 is prevented from leaking out from the gap between the ball 37 and the front end opening of the ball holding chamber.

The pressurized writing instrument 10 of this embodiment includes a barrel 20, a refill 30 arranged in the barrel 20 and having an ink storage tube 33 filled with ink 31, and a pressurizing mechanism 50 that applies pressure to the rear end of the ink 31. The pressurizing mechanism 50 includes an elastic member 80 and a pressing member 60 located behind the elastic member 80. The elastic member 80 includes a rear member 81 having an opening 83, a side member 85 extending forward from the periphery of the rear member 81, and a first internal space S1 surrounded by the rear member 81 and the side member 85. The area of the cross section of the first internal space S1 perpendicular to the central axis A of the barrel 20 decreases toward the rear. When the elastic member 80 moves rearward, the front end 61 of the pressing member 60 abuts against the elastic member 80, sealing the opening 83, forming a pressurized chamber C including the first internal space S1. At least a portion of the elastic member 80 deforms, reducing the volume of the pressurized chamber C.

According to such a pressure-sensitive writing instrument 10, the capacity of the pressure chamber C can be made larger than that of pressure-sensitive writing instruments of the prior art. When the capacity of the pressure chamber C is increased, the change in pressure force becomes small even if the elastic member 80 is deformed relatively greatly. Therefore, it becomes easier to make minute changes in pressure force. This makes it possible to stably generate pressure force in the pressure-sensitive writing instrument 10. In particular, the pressure-sensitive writing instrument 10 can stably generate small pressure force.

In addition, because the pressing force required to deform the elastic member 80 is reduced, the resilient force required to release the deformation of the elastic member 80 can be reduced. In other words, the resilient force of the resilient member 55 can be reduced. This reduces the pressing force required to properly exert pressure on the ink when the user presses the pen tip against the writing surface to write. Therefore, the user can properly press the rear end of the ink 31 by simply pressing the pen tip against the writing surface with a light force.

In the pressure-type writing instrument 10 of this embodiment, in a cross section including the central axis A, the side member 85 is curved so as to protrude in a direction away from the central axis A.

With this type of pressure-type writing instrument 10, the side members 85 of the elastic member 80 can be deformed more easily. Therefore, the pressure-type writing instrument 10 can generate a pressure force more stably. In particular, the pressure-type writing instrument 10 can generate a small pressure force more stably.

In addition, the pressing force required to deform the elastic member 80 can be further reduced. In other words, the resilience force required to release the deformation of the elastic member 80 can be further reduced. This further reduces the pressing force required to properly exert pressure on the ink when the user presses the pen tip against the writing surface to write.

In the pressure-type writing instrument 10 of this embodiment, the rear member 81 includes an inner region R1 that includes the contour of the opening 83 and surrounds the opening 83, and an outer region R2 that is located radially outward from the inner region R1, and the thickness T1 of the inner region R1 is greater than the thickness T2 of the outer region R2.

With this type of pressure-type writing instrument 10, when the elastic member 80 deforms, the amount of deformation of the rear member 81 in the inner region R1 located near the opening 83 can be made smaller than the amount of deformation of the rear member 81 in the outer region R2. This makes it possible to prevent a gap from being generated between the inner region R1 and the front end 61 of the pressing member 60 due to deformation of the elastic member 80. Therefore, the sealing ability of the opening 83 by the pressing member 60 can be effectively improved.

In the pressure-type writing instrument 10 of this embodiment, the opening 83 does not allow the front end 61 of the pressing member 60 to be inserted.

This type of pressure-type writing instrument 10 can prevent the opening 83 from being damaged by being rubbed by the pressing member 60.

The pressure-type writing instrument 10 of this embodiment further includes a spacer member 90 that is disposed in front of the elastic member 80 and has a second internal space S2 that communicates with the first internal space S1.

With such a pressure-sensitive writing instrument 10, the capacity of the pressure chamber C can be further increased. Therefore, the pressure-sensitive writing instrument 10 can generate a pressure force more stably. In particular, the pressure-sensitive writing instrument 10 can generate a small pressure force more stably.

The pressurized writing instrument 10 of this embodiment further has a tail plug 53 attached to the rear end of the ink reservoir 33, and at least the portion of the tail plug 53 that comes into contact with the ink reservoir 33 is made of an elastic material.

This type of pressurized writing instrument 10 can prevent air from leaking between the ink reservoir 33 and the tail plug 53.

10 Pressurized writing instrument 20 Barrel 21 Front barrel 23 Front end opening 25 Grip member 26 Rear barrel 27 Inner surface 28 Rear end opening 29 Receiving member 30 Refill 31 Ink 32 Ink follower 33 Ink storage barrel 34 Ballpoint pen tip 35 Tip holder 36 Tip body 37 Ball 38 Elastic member 41 Knock body 43 Rotating cam member 45 Receiving portion 47 Elastic member 50 Pressurizing mechanism 51 Refill holding member 53 End plug 55 Elastic member 56 Receiving member 57 Receiving portion 58 Protruding portion 59 Claw portion 60 Pressing member 61 Front end 63 Small diameter portion 65 Medium diameter portion 67 Large diameter portion 69 Shoulder portion 70 Guide member 71 Rear portion 72 Front portion 73 Through hole 74 Contact portion 75 Guide portion 76 Claw portion 77 Receiving portion 78 Inner step portion 80 Elastic member 81 Rear member 83 Opening 85 Side member 90 Spacer member 92 Outer step portion C Pressurizing chamber R1 Inner region R2 Outer region S1 First internal space S2 Second internal space T1 Thickness T2 Thickness da Axial direction

Claims (6)

A shaft cylinder,
a refill disposed within the barrel and having an ink reservoir filled with ink;
A pressure mechanism that applies pressure to the rear end of the ink,
The pressure mechanism includes an elastic member and a pressing member located behind the elastic member.
The elastic member has a rear member having an opening, a side member extending forward from a peripheral edge of the rear member, and a first internal space surrounded by the rear member and the side member,
The area of a cross section of the first internal space perpendicular to the central axis of the barrel decreases toward the rear,
When the elastic member moves rearward, the front end of the pressing member abuts against the elastic member to seal the opening, thereby forming a pressure chamber including the first internal space, and the volume of the pressure chamber decreases as at least a portion of the elastic member deforms. The pressure-type writing instrument according to claim 1, wherein the side members are curved so as to protrude away from the central axis in a cross section including the central axis. The rear member includes an inner region including a contour of the opening and surrounding the opening, and an outer region positioned radially outward relative to the inner region,
The pressure-type writing instrument according to claim 1 or 2, wherein the thickness of the inner region is greater than the thickness of the outer region. The pressure-type writing instrument according to any one of claims 1 to 3, wherein the opening does not allow the front end of the pressing member to be inserted. The pressure-type writing instrument according to any one of claims 1 to 4, further comprising a spacer member disposed in front of the elastic member and having a second internal space communicating with the first internal space. The ink container further includes a tail plug attached to a rear end of the ink container.
6. The pressure type writing implement according to claim 1, wherein at least a portion of said tail plug which contacts said ink reservoir is made of an elastic material.