Writing instrument cap and writing instrument

Abstract

To provide a cap for a writing utensil which prevents ink from drying during non-writing and enables a user to enjoy a smooth operation feeling during attachment and detachment. Another object of the present invention is to provide a writing instrument including the writing instrument cap.SOLUTION: The writing instrument cap 100 includes an outer cap 10, an inner cap 20, a first coil spring 30 disposed between the outer cap 10 and the inner cap 20 and configured to transmit a pressing force received by the inner cap 20 to the outer cap 10, and a second coil spring 40 configured to transmit the pressing force to the outer cap 10 together with the first coil spring 30 when a length of the first coil spring 30 along an axial direction is compressed to a predetermined length, wherein a resilient force of the first coil spring 30 is smaller than a resilient force of the second coil spring 40. The writing utensil is equipped with the cap 100 for the writing utensil and the writing utensil body 200.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a writing instrument cap that is provided on a writing instrument such as a fountain pen, a water-based ballpoint pen, or a felt-tip pen, and to a writing instrument that is provided with this writing instrument cap. [Background technology]

[0002] Some writing instrument caps are equipped with an inner cap that seals the pen tip and keeps it airtight to prevent ink from drying out when not writing. For example, Patent Document 1 below discloses a writing instrument cap that "has a spring cap fixed to the outer cap, a retaining member with one end protruding from the opening of the inner cap, an annular elastic member at one end of the retaining member that elastically presses against the outer periphery of the neck, and at least two slits at the open end of the inner cap to form a plurality of swingable tongues that elastically press against the rear end of the inner cap." With this writing instrument cap, the pen tip can be reliably made airtight when the neck is fitted, preventing evaporation of ink, and when the rear barrel is fitted, the inner cap together with the spring cap holds the rear barrel, allowing for stable fitting. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-301883 Summary of the Invention [Problem to be solved by the invention]

[0004] Writing instruments are sometimes considered to be items of personal preference, and the feel of operation can greatly influence the quality of high-end products. Generally, when using a writing instrument, you first remove the cap, write, and then put the cap back on and put it away. The writing feel during writing is a major factor in determining the quality of the feel, and various improvements have been made to this day. Meanwhile, the attaching and detaching of the cap, which occur before and after the above steps, are also important actions that affect the user's impression of the feel of the writing instrument.

[0005] For example, in the case of a writing instrument cap that is attached to and detached from the writing instrument body by screwing in a screw groove, when you hold the writing instrument cap in your hand and turn it, you can feel the smoothness of the screw groove with your fingers, and you can enjoy the luxurious feel that comes from the high machining precision. However, simply reducing the gap between the male and female threads in an attempt to improve manufacturing precision can result in squeaking when turning the writing instrument cap, or if fine particles of dust get in between the male and female threads, the cap may not be able to be completely tightened, causing the ink to dry out. Conversely, increasing the gap between the male and female threads to make the writing instrument cap easier to turn is also an option. However, in that case, the male and female threads will inevitably collide with each other every time the writing instrument cap is turned, resulting in an unpleasant rattle that is felt by the user, significantly diminishing the luxurious feel.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a writing instrument cap that not only prevents ink from drying out when not writing, but also provides a smooth feel when attaching and detaching the cap, and also to provide a writing instrument equipped with this writing instrument cap. [Means for solving the problem]

[0007] The present invention employs the following aspects to solve the above problems and achieve the above object.

[0008] (1) A writing instrument cap according to one aspect of the present invention comprises: A writing instrument cap having an accommodation space for accommodating a writing part of a writing instrument body and having an internal thread formed therein to be threadedly engaged with an external thread of the writing instrument body, an outer cap having the receiving space and the female screw formed therein; an inner cap disposed within the housing space so as to be relatively movable along a common axial direction, the inner cap having a sealing space for housing and sealing the writing part and a sealing surface for receiving a pressing force from the writing instrument body; a first resilient member disposed between the outer cap and the inner cap and configured to transmit the pushing force received by the inner cap to the outer cap; a second resilient member that transmits the pushing force to the outer cap together with the first resilient member when the length of the first resilient member along the axial direction is compressed to a predetermined length; Equipped with The resilience of the first resilient member is smaller than the resilience of the second resilient member.

[0009] According to the writing instrument cap described in (1) above, the writing instrument body is first coaxially inserted into the storage space, thereby inserting the writing part into the sealed space of the inner cap. Then, when the male thread contacts the female thread, the writing instrument cap and the writing instrument body are rotated in opposite directions relative to each other to advance the engagement of the male thread with the female thread. At this time, the first resilient member, which has a relatively low resilience, is compressed first by the pushing force, and the resilience generated thereby constantly presses the inner cap toward the writing instrument body. This ensures that the writing part remains sealed within the sealed space and ink evaporation is reliably prevented. Furthermore, even if the user releases the writing instrument cap after turning the writing instrument cap once and then adjusting the angle of their wrist, the resilience generated by the first resilient member maintains contact between the threads of the female and male threads. Therefore, there is no unpleasant noise or feeling caused by rattle when the female and male threads separate and butt against each other. As the writing instrument cap is further attached, the second resilient member begins to compress when the first resilient member is compressed to a predetermined length. At this time, because the resilience of the second resilient member is set higher than that of the first resilient member, the pressing force required for compression switches from a low value for compressing the first resilient member to a high value for compressing the second resilient member. This change in pressing force can be felt as a change in the weight of the rotational torque required to turn the writing instrument cap. Therefore, from the time the second resilient member, which has a higher resilience than the first resilient member, switches to compression until the screwing operation is complete, the resistance when turning the writing instrument cap increases, providing the user with a comfortable, secure feeling. Additionally, the high resilience of the second resilient member not only increases the pressing force of the inner cap against the writing instrument body, but also maintains a tighter engagement between the female and male threads, preventing the writing instrument cap from loosening. Therefore, in addition to preventing ink from drying out when not writing, you can also enjoy a smooth operation feel. Although the above description relates to attaching the writing instrument cap, the same smooth operational feeling can be enjoyed when removing the writing instrument cap.

[0010] (2) In the writing instrument cap described in (1) above, a first torque blocking member interposed between the first resilient member and the inner cap, the first torque blocking member having a first surface abutting the first resilient member and a second surface slidingly contacting the inner cap; may further comprise: According to the writing instrument cap described in (2) above, when the cap is rotated to attach or detach it from the writing instrument body, the inner cap abuts against the writing instrument body at the sealing surface and becomes one with the outer cap, causing the outer cap to rotate relative to them. At this time, if the first resilient member rotates together with the outer cap, the rotational torque tends to be transmitted to the inner cap. However, in this embodiment, a first torque blocking member acting as a washer is interposed between the first resilient member and the inner cap. Therefore, even if the first resilient member rotates together with the first torque blocking member, the first torque blocking member only slides against the inner cap with its second surface. In this way, intentionally rotating the first torque blocking member idly significantly reduces or blocks torque transmission between the first resilient member and the inner cap. Therefore, when a user holds the writing instrument cap in their hand and turns it, the sense of resistance caused by torque transmission between the first resilient member and the inner cap is reduced, allowing for a light and smooth rotation.

[0011] (3) In the writing instrument cap described in (2) above, a second torque blocking member interposed between the second resilient member and the first torque blocking member, the second torque blocking member having a third surface abutting against the second resilient member and a fourth surface slidingly contacting the first torque blocking member; may further comprise: According to the writing instrument cap described in (3) above, when the cap is turned to secure it to the writing instrument body or when it is turned in the reverse direction to remove it from the writing instrument body, the inner cap abuts the sealing surface of the inner cap against the writing instrument body and becomes one with it, causing the outer cap to rotate relative to them. In this embodiment, a second torque blocking member, acting as another washer, is interposed between the second resilient member and the first torque blocking member. Therefore, even if the second resilient member rotates together with the second torque blocking member, the second torque blocking member only slides against the first torque blocking member at its fourth surface. In this way, intentionally rotating the second torque blocking member can significantly reduce or block torque transmission between the second resilient member and the first torque blocking member. Therefore, when a user holds the writing instrument cap in their hand and turns it, the resistance caused by torque transmission between the second resilient member and the first torque blocking member is reduced, allowing for smooth rotation.

[0012] (4) A writing instrument according to one aspect of the present invention comprises: A writing instrument cap according to any one of the above (1) to (3), the writing instrument body having the male thread formed thereon to be threadably engaged with the female thread of the writing instrument cap, When the writing instrument cap is attached to the writing instrument body, the sealing surface of the inner cap abuts against the writing instrument body after the female thread and the male thread begin to screw together. According to the writing instrument described in (4) above, the above-mentioned operational effects of the writing instrument cap can be achieved. Additionally, in the initial stage of attaching the writing instrument cap to the writing instrument body, the resilient force of the first resilient member is not received via the inner cap, allowing the female and male threads to begin to thread smoothly. On the other hand, after the start of threading, the resilient force of the first resilient member is constantly generated, so the threads of the female and male threads remain in contact with each other. Therefore, as described above, there is no unpleasant noise or feeling caused by rattle when the threads of the female and male threads separate and then butt together, allowing for a smooth operation. Additionally, the resilient force of the second resilient member allows the writing part to remain sealed within the sealed space. [Effects of the Invention]

[0013] The writing instrument cap according to the above aspect of the present invention not only prevents ink from drying out when not writing, but also allows for a smooth feel when attaching and detaching the writing instrument cap. A writing instrument equipped with this writing instrument cap can also be provided. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing one embodiment of a writing instrument equipped with a writing instrument cap of the present invention, and is a partial cross-sectional view taken along a cross section including the central axis thereof. [Figure 2] FIG. 2 is a cross-sectional view showing the component configuration of the writing instrument cap, in which each component is viewed along a cross section including the central axis. [Figure 3] 2 is a diagram showing a main part of the writing instrument cap, and is an enlarged cross-sectional view showing part A in FIG. 1. FIG. [Figure 4] This is an explanatory diagram with a simplified configuration to explain the function of the first and second resilient members of the writing instrument cap, and shows the state in which the resilient force of the first resilient member acts between the two threads of the female and male screws that are screwed together. [Figure 5] FIG. 5 is the same explanatory view as FIG. 4, showing a state in which the resilient force of the second resilient member acts between both threads of the female screw and male screw that are screwed together. [Figure 6] FIG. 10 is a cross-sectional view illustrating the state in which the writing instrument cap is housed in the housing space, illustrating the first step of attaching the writing instrument cap to the writing instrument body. [Figure 7] FIG. 7 is a continuation of FIG. 6 and is a cross-sectional view showing a state immediately before the female thread and the male thread come into contact with each other. [Figure 8] FIG. 8 is a continuation of FIG. 7 and is a cross-sectional view showing the state immediately after the female thread and the male thread come into contact with each other. [Figure 9] This is a continuation of Figure 8, and is a cross-sectional view showing the state immediately after the threads of the female screw and the male screw have begun to engage with each other and the sealing surface of the inner cap has come into contact with the sealing surface of the writing instrument body. [Figure 10] 10 is a continuation of FIG. 9, and is a cross-sectional view showing the state immediately before the axial compression of the second resilient member starts after the threads of the female screw and the male screw have been threaded together and the axial compression of the first resilient member has been completed. [Figure 11] 11 is a continuation of FIG. 10 and is a cross-sectional view showing a state in which the threads of the female screw and the male screw have further engaged with each other, and the axial compression of the second resilient member has been completed and the second resilient member has been completely fastened. DETAILED DESCRIPTION OF THE INVENTION

[0015] A writing instrument cap according to one embodiment of the present invention and a writing instrument equipped with this writing instrument cap will be described below with reference to the drawings. In the following description, a central axis CL of the writing instrument is used as a reference for directions. This central axis CL is the central axis of both the writing instrument cap and the writing instrument body. The direction toward the tip of the writing instrument body along the central axis CL, i.e., the leftward direction on the paper in Figure 1, is sometimes referred to as the "tip direction." The direction toward the rearward end of the writing instrument body along the central axis CL, i.e., the rightward direction on the paper in Figure 1, is sometimes referred to as the "rearward direction." The direction including both the "tip direction" and the "rearward direction" is sometimes referred to as the "axial direction." Furthermore, the direction away from the central axis CL in a cross section perpendicular to the central axis CL is sometimes referred to as the "radially outward direction," the direction toward the central axis CL in a cross section perpendicular to the central axis CL is sometimes referred to as the "radially inward direction," and the direction including both the "radially outward direction" and the "radially inward direction" is sometimes referred to as the "radial direction." Finally, the direction around the central axis CL is sometimes referred to as the "circumferential direction."

[0016] First, the overall configuration of the writing implement of this embodiment will be described with reference to FIGS. As shown in Fig. 1, the writing instrument of this embodiment is a fountain pen that includes a writing instrument cap 100 and a writing instrument body 200. In Fig. 1, the rear end portion of the writing instrument body 200 is not shown in order to clearly show the structure of the front end portion. The writing instrument cap 100 comprises an outer cap 10, an inner cap 20, a first coil spring (first resilient member) 30, a second coil spring (second resilient member) 40, a first washer (first torque blocking member) 50, and a second washer (second torque blocking member) 60.

[0017] As shown in FIG. 2, the outer cap 10 is a cylindrical part with a bottom, and has an inner circumferential surface 11 whose cross-sectional shape perpendicular to the central axis CL is circular at each position along the central axis CL. The inner circumferential surface 11 is divided into multiple sections along the central axis CL. Specifically, the inner circumferential surface 11 has a first inner diameter portion 11a that is connected to an opening 12 at the rear end of the outer cap 10 and has the largest inner diameter; a second inner diameter portion 11b that is connected to the tip end (rear end) of the first inner diameter portion 11a and has a slightly smaller inner diameter than the first inner diameter portion 11a; a third inner diameter portion 11c that is connected to the tip end (rear end) of the second inner diameter portion 11b and has a smaller inner diameter than the second inner diameter portion 11b; and a fourth inner diameter portion 11d that is connected to the tip end (rear end) of the third inner diameter portion 11c and has a smaller inner diameter than the third inner diameter portion 11c.

[0018] A cylindrical inner cap holding portion 15, which is coaxial with the central axis CL, is formed radially inside the fourth inner diameter portion 11d and protrudes from the bottom of the outer cap 10 toward the rear end side (opening side). A space for holding the end of the inner cap 20 is formed inside the inner cap holding portion 15. This space has a generally cylindrical shape coaxial with the central axis CL and is divided into two spaces, a first space 15b and a second space 15c, by an annular protrusion 15a formed at a generally central position in the longitudinal direction. The first space 15b is located closer to the tip (rearward) than the second space 15c and has a generally cylindrical shape coaxial with the central axis CL. The second space 15c is located closer to the rear end (opening) than the first space 15b and has a generally cylindrical shape coaxial with the central axis CL. The first space 15b and the second space 15c are coaxially arranged, with the rear end of the first space 15b connected to the annular protrusion 15a and the tip of the second space 15c connected to the annular protrusion 15a.

[0019] The inner diameter of the annular protrusion 15a is smaller than both the inner diameter of the first space 15b and the inner diameter of the second space 15c. An annular locking surface facing the first space 15b is formed on the leading end side of the annular protrusion 15a. Similarly, an annular locking surface facing the second space 15c is formed on the rear end side of the annular protrusion 15a. Both of these locking surfaces are annular flat surfaces perpendicular to the central axis CL. The rear end (opening side) of the second space 15c is formed with a shallowly dug annular groove 15c1 so that the inner diameter is partially enlarged. An annular locking surface coaxial with the central axis CL is formed on each of the front and rear ends of the annular groove 15c1. A space having a substantially cylindrical circumferential surface is formed between the pair of locking surfaces.

[0020] The outer peripheral surface of the inner cap holding portion 15 has a cylindrical shape that is coaxial with the central axis CL, and has a locking surface 15d at its tip (rear side) that is formed between the fourth inner diameter portion 11d and the inner cap holding portion 15. The locking surface 15d is an annular flat surface that is perpendicular to the central axis CL. Further, at the rear end of the inner cap holding portion 15, a stopper surface 15e is formed that is perpendicular to the central axis CL.

[0021] The opening 12 has a circular shape when viewed from the opposite side along the central axis CL. On the other hand, the side of the outer cap 10 opposite the opening 12, i.e., the tip side of the outer cap 10, is closed and has a circular bottom surface 14 that is perpendicular to the central axis CL. Because the outer cap 10 has no other openings other than the opening 12, the space from the opening 12 to the bottom surface 14 forms an accommodation space a that accommodates the inner cap 20, the first coil spring 30, the second coil spring 40, the first washer 50, and the second washer 60. A female thread 13 is formed on the tip end side (rear side) of the first inner diameter portion 11a, and is coaxial with the center axis CL. The female thread 13 is a spiral groove formed with a predetermined width from the connection position between the first inner diameter portion 11a and the second inner diameter portion 11b toward the rear end side (opening side).

[0022] As shown in Figure 2, the inner cap 20 has a shaft portion 21 that is inserted into and supported by the inner cap holding portion 15, and a sealing tube 22 that is coaxially connected to the rear end side (opening side) of the shaft portion 21. The shaft portion 21 is a long, generally cylindrical shaft body that extends along the central axis CL, and has an annular protrusion 21a formed on its tip side (rear side). The outer diameter of the annular protrusion 21a is larger than the outer diameter of the rest of the shaft portion 21. A locking surface that forms an annular plane perpendicular to the central axis CL is formed on the rear end side of the annular protrusion 21a. Further, a tip surface 21b is formed on the tip side of the shaft portion 21, and is disposed opposite to the bottom surface 14 with a gap therebetween. The tip surface 21b is a circular flat surface that is coaxial with the central axis CL and perpendicular to the central axis CL.

[0023] The sealing cylinder 22 has a bottom wall portion 22a and a peripheral wall portion 22b. The bottom wall portion 22a is a circular plate coaxially connected to the rear end of the shaft portion 21. Of the two surfaces of the bottom wall portion 22a, the surface to which the rear end of the shaft portion 21 is connected forms an annular inner cap side sliding surface 22a1 that is perpendicular to the central axis line CL. The peripheral wall portion 22b is a cylindrical body integrally connected to the outer periphery of the bottom wall portion 22a, and has an inner diameter that tapers from its front end (rear end) toward its rear end (opening side). The peripheral wall portion 22b also has an opening 22c at its rear end. The opening 22c has a tapered surface that tapers from its front end (rear end) toward its rear end (opening side). The space defined by one side of the bottom wall portion 22a and the inner peripheral surface of the peripheral wall portion 22b forms a sealed space b. The sealed space b is connected to the external space of the sealing tube 22 only at the opening 22c. Since the inner cap 20 is disposed within the outer cap 10, the sealed space b is formed within the accommodation space a. An annular protrusion 22b1 is formed on the outer peripheral surface of the rear end (opening side) of the peripheral wall portion 22b. The annular protrusion 22b1 has an outer diameter substantially the same as the diameter of the third inner diameter portion 11c of the outer cap 10, and is in sliding contact with the third inner diameter portion 11c in the direction along the central axis CL.

[0024] The first coil spring (first resilient member) 30 is a spring whose inner and outer diameters are constant at each position along the central axis CL, and whose wire diameter is also constant along its entire length. The wire diameter of the first coil spring 30 is smaller than that of the second coil spring 40. The compression stroke of the first coil spring 30 is longer than that of the second coil spring 40. The resilience of the first coil spring 30 when the writing instrument cap 100 is assembled as shown in FIG. 1 is lower than that of the second coil spring 40, and a specific value can be exemplified as 0.10 N to 0.49 N. The ends of the first coil spring 30 may be left as they are during manufacturing, or may be slightly polished.

[0025] The second coil spring (second resilient member) 40 is a spring whose inner and outer diameters are constant at each position along the central axis CL, and whose wire diameter is also constant along its entire length. The wire diameter of the second coil spring 40 is thicker than that of the first coil spring 30. The compression stroke of the second coil spring 40 is shorter than that of the first coil spring 30. The winding direction of the second coil spring 40 is the same as that of the first coil spring 30. The resilience of the second coil spring 40 when the writing instrument cap 100 is assembled as shown in FIG. 1 is higher than that of the first coil spring 30, and a specific value can be exemplified as 1.96 N to 3.43 N. The ends of the second coil spring 40 may be left as they are during manufacturing, or may be slightly polished.

[0026] With respect to the above-mentioned exemplary ranges of resilience, when the writing instrument cap 100 is assembled and the compression starts, the ratio between the resilience of the first coil spring 30 and the resilience of the second coil spring 40 is set to be extremely low, approximately 0.05 times that of the second coil spring 40. On the other hand, when the writing instrument cap 100 is assembled and the compression ends, the ratio between the resilience of the second coil spring 40 and the resilience of the first coil spring 30 is set to be high, approximately 7 times that of the first coil spring 30. As will be described in detail later, when the writing instrument cap 100 is turned to attach to the writing instrument body 200, only the weaker first coil spring 30 is compressed at the start of the turn, and therefore the rotational torque required to turn the writing instrument cap 100 is low, allowing it to be turned easily. Then, as you continue to turn it and start compressing the second coil spring 40, the first coil spring 30 also continues to be compressed, but because the rotational torque compressing the second coil spring 40, which is set to be stronger, becomes dominant, the rotational operation becomes a little heavier halfway through, and you can feel a firm tightening sensation.

[0027] Returning to the explanation of Figure 2, the first washer 50 is a substantially hollow disk-shaped component, and its surface on the tip side (rear side) forms an annular surface (first surface) 51 that abuts against the first coil spring 30. An annular protrusion 52 that protrudes toward the tip side (rear side) is formed coaxially on this annular surface 51. The outer diameter of the annular protrusion 52 is substantially equal to the inner diameter of the first coil spring 30. Meanwhile, the surface on the rear end side (opening side) of the first washer 50 forms an annular washer-side sliding surface 53 that comes into sliding contact with the inner cap-side sliding surface 22a1 of the inner cap 20. A circular opening 54 is formed in the center of the first washer 50, and the shaft 21 of the inner cap 20 is inserted into this opening. When the shaft 21 is passed through the first washer 50 and supported, the outer peripheral surface of the annular protrusion 52 becomes an annular surface that is coaxial with the central axis CL, and the first coil spring 30 assembled to this annular surface is also naturally positioned so as to be coaxial with the central axis CL.

[0028] The second washer 60 is a generally hollow cylindrical part, and its rear end (opening side) surface forms an annular surface 61 that abuts against the annular surface 51 of the first washer 50. An annular protrusion 62 that protrudes toward the front end (rear side) is coaxially formed on the front end (rear side) of the second washer 60. The outer diameter of the annular protrusion 62 is generally equal to the inner diameter of the second coil spring 40. In addition, an annular protrusion 63 that protrudes radially outward is coaxially formed on the outer circumferential surface of the second washer 60. A circular opening 64 is formed in the center of the second washer 60, and the shaft 21 of the inner cap 20 is inserted into this opening. When the shaft 21 is passed through the second washer 60 and supported, the outer peripheral surface of the annular protrusion 62 becomes an annular surface that is coaxial with the central axis CL, and the second coil spring 40 assembled to this annular surface is also naturally positioned so as to be coaxial with the central axis CL.

[0029] The positional relationship of the above-described components when assembled is shown in Figure 3. Note that Figure 3 is an enlarged view of part A in Figure 1, and shows the state in which writing instrument cap 100 has been screwed onto writing instrument body 200 and fully tightened. As shown in FIG. 3 , when the shaft portion 21 of the inner cap 20 is inserted through the first washer 50 and the second washer 60 and then assembled into the outer cap 10, the annular protrusion 21a of the shaft portion 21 is journaled by the inner peripheral surface of the first space 15b. In addition, the outer peripheral surface of the shaft portion 21 is journaled by the inner peripheral surface of the annular protrusion 15a. Furthermore, the outer peripheral surface of the shaft portion 21 is journaled by the inner peripheral surface of the annular groove 15c1 via the outer peripheral surface of the annular protrusion 63 of the second washer 60. In this way, the shaft portion 21 is coaxially supported within the outer cap 10 at three locations in its longitudinal direction. Therefore, including the annular protrusion 22b1, the inner cap 20 as a whole is supported at four locations in its longitudinal direction so as to be freely movable in the longitudinal direction.

[0030] As shown in FIG. 3, the movable range of the inner cap 20 when moving toward the front end (rear end) is the range until the inner cap 20 abuts against the stopper surface 15e with the first washer 50 sandwiched therebetween. Conversely, the movable range of the inner cap 20 when moving toward the rear end (opening side) is the range until the annular protrusion 21a moves to the right side of the page in FIG. 3 and abuts against the annular protrusion 15a. The first washer 50 is constantly pressed against the inner cap-side sliding surface 22a1 of the inner cap 20 by the elastic force of the first coil spring 30, and therefore moves together with the inner cap 20. At this time, the first coil spring 30 expands and contracts as the inner cap 20 moves, but because it is constantly coaxially supported by the annular protrusion 52, an even elastic force can be applied to the inner cap 20 in the circumferential direction. Furthermore, by making the first coil spring 30 relatively large in diameter and the second coil spring 40 relatively small in diameter, it is possible to arrange them coaxially and reduce the size without interfering with the expansion and contraction movements of the two.

[0031] On the other hand, the movable range of the second washer 60 is the range in which the annular protrusion 63 can move within the annular groove 15c1 in the left-right direction of the page in Figure 3. In this way, the movement stroke of the inner cap 20 is set relatively long so that the pushing force from the inner cap 20 is received first, and the movement stroke of the second washer 60 is set relatively short so that the pushing force from the inner cap 20 is received with a time lag. This makes it possible to switch from the time when the elastic force of the first coil spring 30 acts on the inner cap 20 to the time when the elastic force of the second coil spring 40 predominantly acts on the inner cap 20. This switching will be described later in the description of Figures 4 and 5.

[0032] Returning to FIG. 1, the writing implement body 200 includes a pen tip portion (writing portion) 70, a neck portion 80, and a body portion 90. The pen tip 70 receives ink from a cartridge 92 inside the body 90, enabling writing on paper. Because the pen tip 70 is constantly supplied with ink, it must be sealed in a closed space when not in use, otherwise the ink will evaporate and residual ink will solidify in the ink flow paths, etc. In this case, writing may become difficult even after refilling with ink, and maintenance such as time-consuming cleaning of the pen tip 70 will be necessary.

[0033] The writing instrument cap 100 prevents this hassle by sealing the pen tip portion 70 within the sealed space b. However, with conventional writing instrument caps, the sealability of the sealed space covering the pen tip portion can be unconsciously impaired due to insufficient tightening by the user or loosening caused by external force. In contrast, in the writing instrument cap 100 of this embodiment, the inner cap 20 is pressed against the pen tip portion 70 by the strong elastic force of the second coil spring 40, so that the writing instrument cap 100 does not easily loosen even when subjected to external force, and the sealed state of the pen tip portion 70 can be maintained. In addition, when the user attaches the writing instrument cap 100 to the writing instrument body 200, the user can feel the switch from a weak rotation operation to compress the first coil spring 30 to a stronger rotation operation to compress the second coil spring 40, giving them a sense of tightness, and therefore preventing the user from tightening the cap insufficiently.

[0034] As shown in FIG. 1, the neck portion 80 is a portion coaxially fixed to the rear end of the nib portion 70, and has a gentle recess 81 formed on its outer surface to allow the user to hold the neck portion 80 between their fingertips when writing. In the writing instrument cap 100 of this embodiment, the opening 22c of the inner cap 20 is aligned with a sealing surface 82 formed on the neck portion 80 closer to the tip than the recess 81. Therefore, when the writing instrument cap 100 is attached, even if ink drips from the nib portion 70, it does not reach the recess 81. Therefore, when the user removes the writing instrument cap 100 and holds the recess 81 between their fingertips, the user's fingertips are prevented from being soiled by ink.

[0035] As shown in Figure 1, the body 90 is coaxially fixed to the rear end of the neck 80 and houses a substantially cylindrical cartridge 92. The cartridge 92 is a disposable type filled with ink. Instead of the disposable cartridge 92, a converter may be used, which the user fills with ink and reuses. A male thread 91 is formed on the tip side of the body 90. The male thread 91 is a helical thread centered on the central axis CL and can be threadably engaged with the female thread 13 of the outer cap 10. Therefore, when the writing instrument cap 100 is attached to the writing instrument body 200, the writing instrument body 200 is coaxially held within the writing instrument cap 100 at two points: a support position between the male thread 91 and the female thread 13, and a support position between the seal surface 82 and the opening 22c. Although not shown in the drawings, when writing, the removed writing instrument cap 100 can be coaxially fitted and fixed to the rear end of the barrel 90.

[0036] The configurations of the writing instrument cap 100 and the writing instrument body 200 have been described separately above. Next, the switching of rotational torque when attaching the writing instrument cap 100 to the writing instrument body 200 will be described using Figures 4 and 5. Figures 4 and 5 are explanatory diagrams that simplify the configuration to explain the functions of the first coil spring 30 and the second coil spring 40, and do not include the first washer 50, second washer 60, nib portion 70, etc.

[0037] First, as shown in FIG. 4, the female thread 13 of the writing instrument cap 100 is threaded onto the male thread 91 of the writing instrument body 200, and then the threading therebetween is advanced. As a result, the sealing surface 82 of the writing instrument body 200 advances toward the tip (rearward) and abuts against the opening 22c of the inner cap 20, applying a pushing force F1. This pushing force F1 axially compresses the first coil spring 30 via the inner cap 20. At this point, the transmission path of the pushing force F1 from the inner cap 20 to the second coil spring 40 is cut off, so only the first coil spring 30 is compressed. The compressed first coil spring 30 then generates a resilient force as it attempts to return to its pre-compression length. This resilient force becomes a biasing force F2 that presses the inner cap 20 against the sealing surface 82.

[0038] The pushing force F1 and the biasing force F2 are in an action-reaction relationship and therefore have equal values. As shown in the rectangular box in Figure 4, the pushing force F1 and the biasing force F2 are similarly applied between the male thread 91 and the female thread 13. The resilience of the first coil spring 30 at the start of compression when subjected to the pushing force F1 can be, for example, 0.10 N. The resilience of the first coil spring 30 increases as the compression progresses, and the resilience just before the second coil spring 40 starts to compress can be, for example, 0.49 N.

[0039] As described above, the resilience (or spring constant) of the first coil spring 30 is set to be lower than the resilience (or spring constant) of the second coil spring 40. The reason for this is that the resilience of the first coil spring 30 is applied not to completely seal the pen tip portion 70 with the inner cap 20, but to maintain tight contact by pressing the male thread 91 and the female thread 13 together. That is, when a user attaches the writing instrument cap 100 to the writing instrument body 200, they manually apply torque to rotate them in opposite directions. However, by lowering the resilience of the first coil spring 30 as described above, the pushing force F1 and the biasing force F2 can be kept very small. As a result, the rotation is performed with the minimum force necessary to maintain close contact between the male thread 91 and the female thread 13. The frictional force between the male thread 91 and the female thread 13, which slide together during this rotation, is directly proportional to the pressing force generated between them. Therefore, by keeping the pushing force F1 and the biasing force F2 very small, the frictional force generated between them is also significantly reduced. Therefore, the torque required to rotate the writing instrument cap 100 relative to the writing instrument body 200 is also extremely small, allowing for smooth rotation.

[0040] Furthermore, while turning the writing instrument cap 100, the male thread 91 and the female thread 13 are always kept in contact by the elastic force of the first coil spring 30, so there is no unpleasant noise or tactile sensation that would occur when the male thread 91 and the female thread 13 separate or collide with each other. That is, when turning the writing instrument cap 100, the user must temporarily release the writing instrument cap 100, return their wrist to its original angle, and re-hold the writing instrument cap 100 after completing one turn and before starting the second turn. If the first coil spring 30 were not provided, the writing instrument cap 100 would become free when the user released their hand and be supported only by the threaded engagement between the male thread 91 and the female thread 13. Because there would be play between them, rattles would occur, resulting in noise. In contrast, because the writing instrument cap 100 of this embodiment includes the first coil spring 30, the male thread 91 and the female thread 13 can continue to be kept in contact by the elastic force even while the user temporarily releases their hand from the writing instrument cap 100 and re-holds it. As described above, while turning the writing instrument cap 100 to compress the first coil spring 30, a light, noiseless and comfortable operation can be enjoyed.

[0041] Continuing to turn the writing instrument cap 100 from the state shown in Figure 4 will result in the state shown in Figure 5. In this state, in addition to compressing the first coil spring 30, the second coil spring 40 is also compressed. However, as described above, the resilience of the second coil spring 40 is set higher than the resilience of the first coil spring 30, so the relatively high resilience of the second coil spring 40 becomes dominant. Therefore, the resilience of the second coil spring 40 mainly becomes the biasing force F2, and it becomes necessary to increase the pushing force F1 accordingly. More specifically, by configuring the pushing force F1 and the biasing force F2 to be switched to higher values, the frictional force generated between the male thread 91 and the female thread 13 is increased. This increases the rotational torque required to rotate the writing instrument cap 100 relative to the writing instrument body 200, and the user can feel this increase in rotational torque as a tactile response.

[0042] Furthermore, torque can be increased stepwise by switching from the first coil spring 30, which has a low resilience, to the second coil spring 40, which has a high resilience. Therefore, the user can sense through the tactile feedback that the rotation operation has reached the final stage, and that the inner cap 20 is already pressed against the nib portion 70 with a strong resilience F2, thereby forming a sealed space b and sealing the nib portion 70. Typically, the sealed state of the interior of a writing instrument cap cannot be confirmed with the naked eye unless the cap is made of a see-through material. In contrast, the writing instrument cap 100 of this embodiment allows the user to grasp the sealed state of the interior through tactile feedback without directly viewing the interior, thereby providing a reliable seal and a high sense of security. In addition, by increasing the resilience of the second coil spring 40, even if an external force is applied to the writing instrument cap 100 after tightening, the frictional force between the male thread 91 and the female thread 13 remains high as described above, preventing unintentional loosening.

[0043] Since fully compressing a coil spring tends to shorten its component lifespan, the dimensions and arrangement of the first coil spring 30 are set so that it continues to be compressed without being fully compressed even while the second coil spring 40 is being compressed. The same is true for the second coil spring 40, which is structured so that the compression operation is completed before it is fully compressed when the inner cap 20 abuts against the stopper surface 15e via the first washer 50. Therefore, the user will feel three different responses: a first stage in which the first coil spring 30 is lightly compressed, a second stage in which the second coil spring 40 is firmly compressed, and a third stage in which the inner cap 20 abuts against the stopper surface 15e via the first washer 50 and stops.

[0044] The operation of attaching the writing instrument cap 100 to the writing instrument having the above-described configuration will be described in chronological order with reference to FIGS. 6 is a diagram illustrating the first step in attaching the writing instrument cap 100 to the writing instrument body 200, and is a cross-sectional view showing the state in which the pen tip portion 70 is accommodated in the accommodation space a. At this point, the male thread 91 and the female thread 13 have not yet started to be threaded together, and the opening 22c and the sealing surface 82 are still open. Therefore, although the tip portion of the pen tip portion 70 has entered the inner cap 20, the sealing space b has not yet been formed, and so the pen tip portion 70 is not sealed.

[0045] 7 is a continuation of Figure 6 and is a cross-sectional view showing the state immediately before the male thread 91 and the female thread 13 come into contact. At this point, the male thread 91 and the female thread 13 have not yet started to be threaded together, and the opening 22c and the seal surface 82 are still open. Therefore, although the tip of the nib portion 70 has entered the inner cap 20, the seal space b has not yet been formed, and so the nib portion 70 is not sealed.

[0046] 8 is a continuation of FIG. 7 and is a cross-sectional view showing the state immediately after the male thread 91 and the female thread 13 come into contact. At this point, the tip of the male thread 91 and the rear end of the female thread 13 come into contact for the first time, but the threading between them has not yet begun, and there is also a slight gap between the opening 22c and the seal surface 82. Therefore, although the tip portion of the nib portion 70 has entered the inner cap 20, the formation of the seal space b has not yet been completed, and the nib portion 70 is not yet sealed.

[0047] Figure 9 is a continuation of Figure 8 and is a cross-sectional view showing the state immediately after the rotation of the writing instrument cap 100 relative to the writing instrument body 200 has begun. At this point, the threads of the male thread 91 and the female thread 13 have begun to engage with each other, and the opening 22c of the inner cap 20 has just come into contact with the sealing surface 82 of the writing instrument body 200. Then, the neck portion 80 begins to compress the first coil spring 30 via the inner cap 20, and both the pushing force F1 and the biasing force F2 begin to be generated. Furthermore, because the nib portion 70 is inside the inner cap 20 and the opening 22c and the sealing surface 82 are aligned, a sealing space b is formed.

[0048] From this state, if the writing instrument cap 100 is further turned relative to the writing instrument body 200, the neck portion 80 advances deeper into the outer cap 10. Then, the neck portion 80 compresses the first coil spring 30 axially via the inner cap 20 and the first washer 50. As a result, the resilient force of the first coil spring 30 is generated as a biasing force F2, and the threads between the male thread 91 and the female thread 13 are pressed against each other, maintaining constant contact. At the same time, the inner cap 20 also maintains a tight seal around the nib portion 70.

[0049] During this process, the writing instrument cap 100 is rotated relative to the writing instrument body 200. At this time, the inner cap 20 abuts against the neck portion 80, forming a single unit, and therefore rotates within the outer cap 10. Because the first coil spring 30 and the inner cap 20 are separated by the first washer 50, the inner cap 20 rotates while sliding against the first washer 50. Therefore, the first coil spring 30 itself does not rotate within the outer cap 10 but is only compressed axially. Therefore, even if the end of the first coil spring 30 is cut off, the cut end surface does not directly contact the inner cap-side sliding surface 22a1 of the inner cap 20 and cause any jamming. Therefore, only axial compressive force is transferred between the inner cap 20 and the first coil spring 30, and rotational torque is not easily transmitted. Additionally, as described above, unpleasant noise caused by rattles due to separation and collision between the male thread 91 and the female thread 13 is also suppressed. Therefore, smooth rotation can be performed continuously from the start to the end of compression of the first coil spring 30, and the user can enjoy a high-quality operating feel as the male thread 91 and female thread 13 slide against each other.

[0050] FIG. 10 is a continuation of FIG. 9 and is a cross-sectional view showing the state immediately before the axial compression of the second coil spring 40 begins, following the completion of axial compression of the first coil spring 30 as the threads of the male thread 91 and the female thread 13 engage with each other. At this point, the inner cap 20 contacts the second coil spring 40 via the first washer 50 and the second washer 60. The rotation operation continues from the point shown in FIG. 10. While the rotation torque was low until just before the start of the rotation to compress the weak first coil spring 30, a strong torque is now required to compress the strong second coil spring 40. Thus, the rotational load increases stepwise. Sensing this load, the user knows two things: the seal space b has been reliably formed by the strong resilience of the second coil spring 40, and the rotation is nearing completion.

[0051] During this process, the writing instrument cap 100 continues to rotate relative to the writing instrument body 200. At this time, as described above, the inner cap 20 rotates within the outer cap 10. Because the second coil spring 40 and the inner cap 20 are separated by the first washer 50 and the second washer 60, the second coil spring 40 itself does not rotate within the outer cap 10 but is only compressed axially. Therefore, even if the end of the second coil spring 40 is cut off, the cut end surface does not directly contact the inner cap-side sliding surface 22a1 of the inner cap 20 and cause any jamming. Therefore, only axial compressive force is transferred between the inner cap 20 and the second coil spring 40, and rotational torque is not easily transmitted. Additionally, as described above, unpleasant noises caused by separation and collision between the male thread 91 and the female thread 13 are suppressed. Therefore, smooth rotation can be continuously performed from the start to the end of compression of the second coil spring 40, and the user can enjoy the solid operating feel of the male thread 91 and female thread 13 sliding against each other.

[0052] Furthermore, since a strong biasing force F2 is already acting when the second coil spring 40 begins to compress, even if the user stops the rotation operation halfway through without fully tightening, the writing instrument cap 100 will not easily loosen. Therefore, even if the user's rotation operation is incomplete and ends at the point shown in Figure 10, the sealed state of the pen tip portion 70 by the seal space b can be maintained for a long period of time.

[0053] 11 is a continuation of FIG. 10 and is a cross-sectional view showing the state in which the threads of the male thread 91 and the female thread 13 have further engaged with each other, and the axial compression of the second coil spring 40 has been completed, resulting in a fully tightened state. At this point, the inner cap-side sliding surface 22a1 of the inner cap 20 comes into contact with the stopper surface 15e via the first washer 50, and the advancement of the inner cap 20 is stopped. At this point, the user can tell that the inner cap 20 has been fully tightened because further rotation is no longer possible. 11, the strong resilience of the second coil spring 40 always presses the male thread 91 and the female thread 13 together, so that the writing instrument cap 100 does not easily loosen even when subjected to an external force. Therefore, it is possible to maintain the sealed state of the pen tip portion 70 by the seal space b for a long period of time.

[0054] Although one embodiment of the present invention has been described above with reference to the drawings, it is merely an example and is not limited to the above configuration. For example, in the above embodiment, the first coil spring 30 and the second coil spring 40 are separate bodies, but this configuration is not limited to this, and the first coil spring 30 and the second coil spring 40 may also be configured as a single coil spring.

[0055] In the above embodiment, the first washer 50 and the second washer 60 are used to block the transmission of torque between the inner cap 20 and the first coil spring 30 and the second coil spring 40, but these may be omitted. In that case, it is possible to make both the first coil spring 30 and the second coil spring 40 coil springs having a winding direction opposite to the winding direction of the female thread 13.

[0056] To explain this modification, as described above, the first coil spring 30 and the second coil spring 40 are each processed by cutting off their end portions, which inevitably results in a shape that includes a sharp cut surface. Therefore, if the first washer 50 is omitted and the winding direction of the first coil spring 30 is the same as the winding direction of the female thread 13, when the writing instrument cap 100 is turned to attach to the writing instrument body 200, the cut surface of the first coil spring 30 will rotate to meet the inner cap-side sliding surface 22a1 of the inner cap 20, which could cause the sharp cut surface to scrape and slide against the inner cap-side sliding surface 22a1. This sliding contact can cause an unpleasant, catching sensation in the hand, potentially impairing the feel of operation. On the other hand, if the winding direction of the first coil spring 30 is opposite to that of the female thread 13, when the writing instrument cap 100 is turned to attach it to the writing instrument body 200, the cut surface of the first coil spring 30 will rotate in a direction away from the inner cap side sliding contact surface 22a1 of the inner cap 20, and the sharpened cut surface will also rotate in a direction away from the inner cap side sliding contact surface 22a1 while sliding against it. Therefore, the sharpened cut surface will not get caught on the inner cap side sliding contact surface 22a1, allowing for smooth rotation. For the above reasons, when the first washer 50 is omitted, it is better to wind the first coil spring 30 in the opposite direction to the winding direction of the female thread 13. Furthermore, for the same reasons, when the second washer 60 is omitted, it is better to wind the second coil spring 40 in the opposite direction to the winding direction of the female thread 13.

[0057] Furthermore, in the above embodiment, the elastic force of the first coil springs 30 is 0.10 N to 0.49 N, and the elastic force of the second coil springs 40 is 1.96 N to 3.43 N. To add to this, the first coil springs 30 are not fully compressed, so the first coil springs 30 continue to be compressed even while the second coil springs 40 are being compressed. Therefore, the elastic force of the second coil springs 40, which is 1.96 N to 3.43 N, may be a value that includes the elastic force of the first coil springs 30.

[0058] In addition, in the above embodiment, an example was given of the writing instrument cap of the present invention being applied to a fountain pen cap, but this is not limited to fountain pens, and it may also be applied to ballpoint pens or felt-tip pens, etc., in which the writing instrument cap is attached and detached by screwing together male and female threads.

[0059] The gist of the writing instrument cap 100 of the embodiment described above and the writing instrument equipped with the same will be summarized below. (1) As shown in FIG. 1, the writing instrument cap 100 of this embodiment is The writing instrument has an accommodation space a for accommodating the pen tip portion (writing portion) 70 of the writing instrument body 200 and having an internal thread 13 formed therein that is threadably engaged with the external thread 91 of the writing instrument body 200; an outer cap 10 having an accommodation space a and a female screw 13 formed therein; an inner cap (20) disposed within the accommodation space (a) so as to be relatively movable along the direction of a common central axis (CL), and having a sealing space (b) for accommodating and sealing the pen tip portion (70) and an opening (22c) as a sealing surface that receives a pressing force from the writing instrument body (200); a first coil spring (first resilient member) 30 disposed between the outer cap 10 and the inner cap 20, which transmits a pushing force received by the inner cap 20 to the outer cap 10; a second coil spring (second resilient member) 40 that transmits a pushing force to the outer cap 10 together with the first coil spring 30 when the length of the first coil spring 30 along the direction of the central axis CL is compressed to a predetermined length; Equipped with The elastic force of the first coil spring 30 is smaller than the elastic force of the second coil spring 40.

[0060] (2) As shown in FIG. 3, in the writing instrument cap 100 described above in (1), A first washer (first torque blocking member) 50 is interposed between the first coil spring 30 and the inner cap 20 and has an annular surface (first surface) 51 that abuts against the first coil spring 30 and a washer-side sliding surface (second surface) 53 that slides against the inner cap 20. may further comprise:

[0061] (3) As shown in FIG. 2, in the writing instrument cap 100 described above in (2), A second washer (torque blocking member) 60 is interposed between the second coil spring 40 and the first washer 50 and has an annular front surface (third surface) that abuts against the second coil spring 40 and an annular back surface (fourth surface) that slides against the first washer 50. may further comprise:

[0062] (4) As shown in FIG. 8, the writing instrument of the above embodiment has A writing instrument cap 100 according to any one of (1) to (3) above, a writing instrument body (200) having a male thread (91) formed thereon that is adapted to be threadedly engaged with the female thread (13) of the writing instrument cap (100); When attaching the writing instrument cap 100 to the writing instrument body 200, the opening 22c, which is the sealing surface of the inner cap 20, comes into contact with the writing instrument body 200 after the female thread 13 and the male thread 91 begin to screw together. [Explanation of symbols]

[0063] 10 Outer cap 13 Internal thread 20 Inner cap 22c Opening (seal surface) 30 First coil spring (first spring element) 40 Second coil spring (second spring element) 50 First washer (first torque blocking member) 51 Annular surface (first surface) 53 Washer side sliding surface (second surface) 60 Second washer (second torque blocking member) 70 Pen tip (writing part) 91 Male thread 100 Writing Instrument Caps 200 Writing instrument body a. Containment space b Sealing space F1 Pushing force

Claims

1. A writing instrument cap having an accommodation space for accommodating a writing part of a writing instrument body and having an internal thread formed therein to be threadedly engaged with an external thread of the writing instrument body, an outer cap having the receiving space and the female screw formed therein; an inner cap disposed within the housing space so as to be relatively movable along a common axial direction, the inner cap having a sealing space for housing and sealing the writing part and a sealing surface for receiving a pressing force from the writing instrument body; a first resilient member disposed between the outer cap and the inner cap and configured to transmit the pushing force received by the inner cap to the outer cap; a second resilient member that transmits the pushing force to the outer cap together with the first resilient member when the length of the first resilient member along the axial direction is compressed to a predetermined length; Equipped with The resilience of the first resilient member is smaller than the resilience of the second resilient member. A cap for a writing instrument.

2. a first torque blocking member interposed between the first resilient member and the inner cap, the first torque blocking member having a first surface abutting the first resilient member and a second surface slidingly contacting the inner cap; The writing instrument cap according to claim 1, further comprising:

3. a second torque blocking member interposed between the second resilient member and the first torque blocking member, the second torque blocking member having a third surface abutting against the second resilient member and a fourth surface slidingly contacting the first torque blocking member; The writing instrument cap according to claim 2, further comprising:

4. A writing instrument cap according to any one of claims 1 to 3; the writing instrument body having the male thread formed thereon to be threadably engaged with the female thread of the writing instrument cap, When the writing instrument cap is attached to the writing instrument body, the sealing surface of the inner cap abuts against the writing instrument body after the female thread and the male thread start to be screwed together. A writing instrument characterized by:

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