Writing instrument

Abstract

To suppress a decrease in sealability of a storage space for storing a pen point.SOLUTION: The writing instrument 10 includes the barrel 20 having the opening 22a, the writing member 12 having the pen tip 13, the retractable mechanism 40 configured to retract the pen tip 13 from the opening 22a, and the sealing mechanism 70 configured to seal the housing space S for the pen tip 13 in the retracted state of the pen tip 13, wherein the sealing mechanism 70 includes the annular rib 83 formed to surround the opening 22a and the lid member 72 configured to come into contact with the annular rib 83 to close the opening 22a.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a writing instrument. [Background technology]

[0002] Conventionally, there is known a writing instrument that includes a barrel, a writing element having a nib, and a retraction mechanism that causes the nib to protrude from and retract into the barrel. Among such writing instruments, there is also known a writing instrument that includes a sealing mechanism that seals the nib storage space when the nib is retracted to prevent ink from drying out in the nib.

[0003] Patent Document 1 discloses a writing instrument that includes a barrel, a writing body housed inside the barrel, a lid disposed in front of the barrel, and a spring that biases the lid in a direction to close. In this writing instrument, when the writing body moves forward, the lid is pressed against the tip of the writing body and opens. When the writing body moves backward in this state, the writing body is housed inside the barrel, and the resilient force of the spring closes the lid, closing the barrel. This prevents ink from drying out on the writing body while it is housed in the barrel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-112032 Summary of the Invention [Problem to be solved by the invention]

[0005] When the writing body is immersed in the barrel, the nib of the writing body is contained in a specified storage space. At this time, it is necessary for the storage space to be properly sealed with a lid to prevent the ink at the nib from drying out. The component of the barrel that comes into contact with the lid is sometimes formed by injection molding using resin. In injection molding, molten resin is injected into a mold and then cooled to harden the resin. As the resin hardens, the volume of the resin decreases, which can cause unevenness on the surface of the manufactured product. If unevenness occurs on the contact surface of the barrel with the lid, a gap will form between the lid and the contact surface, which may compromise the airtightness of the storage space.

[0006] The present invention has been made in consideration of these points, and aims to prevent a decrease in the sealing performance of the storage space that stores the pen tip. [Means for solving the problem]

[0007] The writing instrument according to the present invention comprises: [1] A writing implement comprising: a barrel having an opening; a writing member having a pen tip; a retraction mechanism for retracting the pen tip from the opening; and a sealing mechanism for sealing an accommodation space for the pen tip when the pen tip is retracted, The sealing mechanism includes: an annular rib formed to surround the opening; a cover member that can contact the annular rib to close the opening; It is a writing instrument having the following features.

[0008] The writing instrument according to the present invention comprises: [2] the annular rib has a top surface; The writing instrument according to [1], wherein the top surface is a flat surface.

[0009] The writing instrument according to the present invention comprises: [3] The writing instrument according to [2] has at least one groove portion communicating with the top surface.

[0010] The writing instrument according to the present invention comprises: [4] the sealing mechanism has a base surface surrounding the annular rib; The writing implement according to [3], wherein the groove portion is provided from the top surface to the base surface.

[0011] The writing instrument according to the present invention comprises: [5] The writing implement according to any one of [2] to [4], wherein the contact angle between the top surface and water is 90 degrees or less.

[0012] The writing instrument according to the present invention comprises: [6] the sealing mechanism has a base surface surrounding the annular rib; The writing implement according to any one of [2] to [4], wherein the contact angle between the base surface and water is smaller than the contact angle between the top surface and water. [Effects of the Invention]

[0013] According to the present invention, it is possible to suppress a decrease in the airtightness of the storage space that stores the pen tip. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram for explaining one embodiment of the present invention, and is a vertical cross-sectional view showing an example of a writing implement in an immersed state. [Figure 2] FIG. 2 is a vertical cross-sectional view showing the writing implement of FIG. 1 in a protruding state. [Figure 3] 3 is an enlarged longitudinal cross-sectional view of the front portion of the writing implement of FIG. 1. FIG. [Figure 4] FIG. 4 is a perspective view showing the inner shaft of the writing implement. [Figure 5] FIG. 5 is a view showing the inner shaft as seen from the front. [Figure 6] FIG. 6 is a side view of a portion of the inner shaft. [Figure 7] FIG. 7 is a diagram showing a modified example of the inner shaft. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present invention will now be described with reference to the drawings. In the drawings attached to this specification, the scale and aspect ratios have been appropriately changed and exaggerated from those of the actual objects for the sake of ease of illustration and understanding.

[0016] Furthermore, terms used in this specification that specify shapes, geometric conditions, and their degrees, such as "parallel," "orthogonal," and "identical," as well as values ​​of lengths and angles, are not to be construed as being bound by strict meanings, but rather as including a range within which similar functions can be expected.

[0017] In this specification, the direction in which the central axis A of the writing instrument 10 extends (longitudinal direction) 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. Along the axial direction da, the side toward the pen tip is referred to as the front, and the side opposite the pen tip is referred to as the rear. Also, along the radial direction, the side closer to the central axis A is referred to as the inside or inner side, and the side away from the central axis A is referred to as the outside or outer side.

[0018] FIG. 1 is a diagram for explaining one embodiment of the present invention, and is a vertical cross-sectional view showing an example of a writing instrument 10 in a retracted state, and FIG. 2 is a vertical cross-sectional view showing the writing instrument 10 in a protruding state.

[0019] The writing instrument 10 of this embodiment includes a writing member 12, a barrel 20, a retractable mechanism 40, and a sealing mechanism 70. The writing instrument 10 extends along a central axis A. The writing member 12 is a member that writes on a writing surface, such as paper. The writing member 12 is housed within the barrel 20. Examples of the writing member 12 include components used in ballpoint pens, fountain pens, and markers. In this embodiment, an example is described in which the writing instrument 10 is a fountain pen. The writing member 12 of this embodiment has a nib 13 provided at the front end, a housing tube 15 that houses ink, a first receiving portion 17, and a protruding portion 19. The housing tube 15 may be, for example, a cartridge type or a converter. The first receiving portion 17 is a forward-facing surface of a step formed on the outer surface of the writing member 12 and receives the elastic force of a first elastic member 42, which will be described later. The protrusion 19 protrudes radially outward from the main body of the writing element 12 .

[0020] The retractable mechanism 40 is a mechanism for alternately switching the writing instrument 10 between a protruding state in which the nib 13 protrudes from the front end opening 20a of the barrel 20 and a retracted state in which the nib 13 is retracted from the front end opening 20a.

[0021] The barrel 20 includes a front barrel 21, a tip member 30 disposed in front of the front barrel 21, and a rear barrel 31 disposed behind the front barrel 21. The central axis of the barrel 20 coincides with the central axis A of the writing instrument 10. A front end opening 20a is provided at the front end of the barrel 20, through which the nib 13 can pass. In this embodiment, the front end opening 20a is formed at the front end of the tip member 30.

[0022] Front barrel 21 is a member having a generally cylindrical shape, and is intended to be grasped with the fingers of a user when writing with writing instrument 10. Front barrel 21 of this embodiment includes inner barrel 22, outer barrel 25 disposed radially outward from inner barrel 22, and first connecting member 26.

[0023] The inner shaft 22 is a member that houses the front portion of the writing member 12 and defines the storage space S for the nib 13. The inner shaft 22 is a member having a generally cylindrical shape with a central axis that coincides with the central axis A. In this embodiment, in the retracted state, the inner shaft 22 houses the entire nib 13. A groove 24 that engages with the protrusion 19 of the writing member 12 is formed on the inner surface of the inner shaft 22. The groove 24 extends in the axial direction da, and by positioning the protrusion 19 of the writing member 12 within the groove 24, the writing member 12 is supported relative to the barrel 20 so as to be movable in the axial direction da but not rotatable in the circumferential direction. The inner shaft 22 is formed from, for example, a resin material such as acrylonitrile-styrene (AS) copolymer resin, acrylonitrile-butadiene-styrene (ABS) copolymer resin, polycarbonate (PC), polypropylene (PP), polyethylene (PE), or elastomer, or a rubber material such as nitrile butadiene rubber (NBR). The inner shaft 22 may be formed from a single member or multiple members. The inner shaft 22 may also be manufactured by injection molding.

[0024] An opening 22a through which the pen tip 13 can pass is formed at the tip of the inner shaft 22. A contact surface 22b is formed around the opening 22a. The contact surface 22b is the surface that comes into contact with the cover member 72 described below in the immersed state. The manner in which the contact surface 22b and the cover member 72 come into contact will be described later.

[0025] Outer shaft 25 is a component visible to the user and is also a component that the user grasps with their fingers when writing with writing instrument 10. Therefore, outer shaft 25 is formed of an appropriate material, taking into consideration design and ease of grip by the user. For example, outer shaft 25 may be formed of resin, elastomer, metal, wood, or the like. First connecting member 26 is a component that forms a connection with rear shaft 31. First connecting member 26 is fixed to the rear end of at least one of inner shaft 22 and outer shaft 25. For example, first connecting member 26 may be fixed to the rear end of at least one of inner shaft 22 and outer shaft 25 by adhesive bonding or insert molding. First connecting member 26 is formed of, for example, resin, metal, or the like. Note that the present invention is not limited to the illustrated example, and outer shaft 25 and first connecting member 26 may be omitted. For example, the entire front shaft 21 may be formed as a single unit.

[0026] Tip member 30 is a member that forms the tip portion of barrel 20. Tip member 30 has the function of protecting the front end of front barrel 21, cover member 72, and resilient member 76. Tip member 30 has a generally truncated cone shape, and its outer diameter decreases toward the front. A front end opening 20a from which nib 13 appears and retracts is formed at the front end of tip member 30. Tip member 30 is connected to front barrel 21 by attaching the rear end of tip member 30 to the front end of front barrel 21. Tip member 30 is connected to front barrel 21 by, for example, press-fitting, adhesive bonding, or threaded engagement of a threaded portion.

[0027] The rear axle 31 is a generally cylindrical member disposed rearward of the front axle 21. The rear axle 31 includes an inner shaft 32, an outer shaft 35 disposed radially outward of the inner shaft 32, a second connecting member 36, and a crown 38.

[0028] The inner shaft 32 is a member that houses the rear portion of the writing member 12. The inner shaft 32 is a member having a generally cylindrical shape. The inner shaft 32 is formed, for example, from resin, metal, wood, or the like. The inner peripheral surface of the inner shaft 32 is formed with a plurality of sawtooth-shaped cam teeth that protrude forward, and grooves that are formed between the cam teeth and extend in the axial direction da.

[0029] The outer shaft 35 is a member that is visible to the user. Therefore, the outer shaft 35 is formed of an appropriate material, taking into consideration design and the like. For example, the outer shaft 35 may be formed of resin, elastomer, metal, wood, or the like. The second connecting member 36 is a member that forms a connection with the front shaft 21. The second connecting member 36 is fixed to the front end of at least one of the inner shaft 32 and the outer shaft 35. For example, the second connecting member 36 may be fixed to the front end of at least one of the inner shaft 32 and the outer shaft 35 by adhesive bonding or insert molding. The second connecting member 36 is formed of, for example, resin, metal, or the like. Note that the present invention is not limited to the illustrated example, and the inner shaft 32 and the outer shaft 35 may be formed of a single member. Furthermore, the inner shaft 32, the outer shaft 35, and the second connecting member 36 may be formed of a single member. In other words, the entire rear shaft 31 may be formed integrally.

[0030] The retractable mechanism 40 is a mechanism for alternately switching the writing instrument 10 between a protruding state and a retracted state. The retractable mechanism 40 of this embodiment includes a knock member 50, a rotating cam member 60, a first resilient member 42, and a second resilient member 44.

[0031] The first resilient member 42 is, for example, a coil spring. The first resilient member 42 is disposed in a compressed state between the first receiving portion 17 of the writing member 12 and the second receiving portion 28 of the barrel 20 (front barrel 21). The second receiving portion 28 is a stepped portion provided on the inner circumferential surface of the barrel 20 (front barrel 21) and includes a surface facing rearward. In this embodiment, the first receiving portion 17 receives a resilient force from the first resilient member 42. As a result, the first resilient member 42 constantly biases the writing member 12 rearward relative to the barrel 20. The first resilient member 42 constitutes a part of the extending / retracting mechanism 40 and also constitutes a part of the sealing mechanism 70, as described below.

[0032] The knock member 50 is a member intended to be operated by the user. The knock member 50 includes an operating portion 52 and an expanded diameter portion 54 located in front of the operating portion 52. The operating portion 52 is the portion that is pressed by the user's finger or the like. The operating portion 52 protrudes rearward from the rear end of the barrel 20 (rear barrel 31). In the retracted state and the extended state, the rear end of the operating portion 52 protrudes rearward from the rear end of the barrel 20. The expanded diameter portion 54 has a radial dimension that is larger than the radial dimension of the operating portion 52. The inner diameter of the rear end of the barrel 20 is large enough that the operating portion 52 can pass through but the expanded diameter portion 54 cannot. Therefore, the knock member 50 will not slip out rearward from the rear end of the barrel 20.

[0033] Cam teeth that protrude forward are formed at the front end of the expanded diameter portion 54. In addition, a protrusion that engages with a groove formed in the inner peripheral surface of the barrel 20 (rear barrel 31) is formed on the outer peripheral surface of the expanded diameter portion 54. With the protrusion engaged with the groove of the barrel 20, the knock member 50 is arranged so as to be movable in the axial direction da but not rotatable in the circumferential direction.

[0034] A hole 56 extending in the axial direction da is formed inside the knock member 50. In this embodiment, the hole 56 is open at the front end of the knock member 50 and closed at the rear end of the knock member 50. An inward protrusion 58 that protrudes radially inward is formed on the inner surface of the hole 56.

[0035] The rotating cam member 60 has, on its outer surface, a plurality of ridges that extend in the axial direction da and engage with grooves in the barrel 20. Cam surfaces that are inclined with respect to the axial direction da and the circumferential direction are formed at the rear ends of the ridges. The cam surfaces engage with cam teeth of the knock member 50. The rotating cam member 60 has a rearward protruding portion 62 that protrudes rearward along the axial direction da. An engaging portion 64 is provided at the rear end of the rearward protruding portion 62. The engaging portion 64 is a protruding portion that protrudes radially outward from the rearward protruding portion 62. The engaging portion 64 engages with the inward protruding portion 58 of the knock member 50 to restrict movement of the knock member 50 and the rotating cam member 60 in the axial direction da.

[0036] A second resilient member 44 is disposed between the knock member 50 and the rotating cam member 60. The second resilient member 44 is, for example, a coil spring. The second resilient member 44 is disposed within the barrel 20 behind the writing member 12. Specifically, the second resilient member 44 is disposed in a compressed state between the knock member 50 and the rotating cam member 60. Therefore, the second resilient member 44 constantly biases the knock member 50 rearward relative to the rotating cam member 60. As a result, the knock member 50 moves rearward relative to the rotating cam member 60, but the engagement portion 64 of the rotating cam member 60 engages with the inward protrusion 58 of the knock member 50, preventing the knock member 50 from moving further rearward relative to the rotating cam member 60. When the engagement portion 64 of the rotating cam member 60 is engaged with the inward protrusion 58 of the knock member 50, the knock member 50 is forced rearward by the second spring member 44, thereby preventing the knock member 50 from rattling.

[0037] The specific structures and operations of the grooves of the barrel 20, the cam teeth and protrusions of the knock member 50, and the ridges and cam surfaces of the rotating cam member 60 are well known, so detailed explanations will be omitted. As an example, the specific structures of these may be the structure of the mechanism disclosed in JP 2013-006281 A.

[0038] The writing instrument 10 of this embodiment has a sealing mechanism 70 that seals the storage space S for the nib 13. This sealing mechanism 70 will be described below, mainly with reference to Figure 3. Figure 3 is an enlarged vertical cross-sectional view showing the front portion of the writing instrument 10 in the immersed state. The sealing mechanism 70 of this embodiment is a mechanism that seals the front end of the storage space S. The sealing mechanism 70 includes a contact surface 22b of the barrel 20 (inner shaft 22), a cover member 72, a resilient member 76, and a pin 78.

[0039] The inner shaft 22 has an opening 22a through which the pen tip 13 can pass and a contact surface 22b surrounding the opening 22a. A cover member 72 is attached to the inner shaft 22. A resilient member 76 biases the cover member 72 toward the contact surface 22b by its resilient force. The resilient member 76 is, for example, a torsion spring. One end of the resilient member 76 is attached to the cover member 72, and the other end is disposed in a recess 29 provided at the front end portion of the inner shaft 22. A pin 78 is disposed extending in a direction perpendicular to the axial direction da. In the example shown in FIG. 3, the pin 78 is inserted into a through hole provided at the front end portion of the inner shaft 22. Furthermore, the pin 78 is inserted into an annular portion provided at the base end of the cover member 72 and a loop portion of the resilient member 76. This allows the cover member 72 to rotate to one side or the other about the pin 78, thereby contacting or separating from the contact surface 22b. That is, the pin 78 also serves as the rotation axis of the cover member 72. A gap providing play may be formed between the annular portion provided at the base end of the cover member 72 and the outer circumferential surface of the pin 78. Even in this case, the pin 78 is essentially the rotation axis of the cover member 72.

[0040] In the retracted state, the cover member 72 closes the front end of the inner shaft 22 to seal the storage space S, and in the protruding state, it allows the nib 13 to protrude. The cover member 72 has an opposing surface 74 that faces the contact surface 22b when the cover member 72 closes the opening 22a. The cover member 72 is biased by a resilient member 76 in a direction to seal the storage space S for the nib 13. In this embodiment, in the retracted state, the resilient force of the resilient member 76 causes the opposing surface 74 of the cover member 72 to contact the contact surface 22b of the inner shaft 22 to close the opening 22a. This seals the storage space S for the nib 13 (see FIGS. 1 and 3). In this case, drying of the ink on the nib 13 is suppressed. When transitioning from the immersed state to the protruding state, the pen tip 13 moves forward and pushes the cover member 72 forward, causing the cover member 72 to open, and the pen tip 13 protrudes forward through the opening 22a and the front end opening 20a (see FIG. 2). In this protruding state, writing with the writing instrument 10 becomes possible.

[0041] Next, we will explain contact surface 22b of inner shaft 22. Fig. 4 is a perspective view showing inner shaft 22 of writing instrument 10. Fig. 5 is a view showing inner shaft 22 as seen from the front. Fig. 6 is a view showing a portion of inner shaft 22 as seen from the side.

[0042] The contact surface 22b in this embodiment includes a base surface 81 and an annular rib 83. The base surface 81 in this embodiment is a plane extending in a direction inclined with respect to the central axis A. The base surface 81 is not a surface that comes into contact with the opposing surface 74 of the lid member 72 in the immersed state. Therefore, the base surface 81 does not have to be a plane.

[0043] The annular rib 83 protrudes from the base surface 81. The annular rib 83 is formed to surround the opening 22a. In this embodiment, the annular rib 83 surrounds the central axis A. The annular rib 83 includes a top surface 85 and a side surface 87. The top surface 85 is a surface that contacts the opposing surface 74 of the lid member 72 in the retracted state. The top surface 85 is preferably flat. In this case, when the opposing surface 74 and the top surface 85 come into contact with each other, the opposing surface 74 and the top surface 85 come into surface contact with each other, effectively preventing air from passing through this contact area. The shape of the top surface 85 is arbitrary as long as it prevents air from passing through the contact area between the opposing surface 74 and the top surface 85. In other words, the shape of the top surface 85 is not limited to a flat surface. The side surface 87 is a surface that connects the top surface 85 and the base surface 81. The side surface 87 may be a curved surface that is convex outward in a cross section passing through the central axis A. The annular rib 83 is formed integrally with the main body of the inner shaft 22 .

[0044] The annular rib 83 is formed seamlessly surrounding the opening 22a, thereby preventing a gap from being formed between the opposing surface 74 and the top surface 85 when the opposing surface 74 and the top surface 85 come into contact with each other. This effectively prevents a decrease in the sealing performance of the storage space S.

[0045] Inner barrel 22 is produced, for example, by injection molding of resin. In injection molding, molten resin is injected into a mold and then cooled to harden the resin. The hardened resin then constitutes inner barrel 22. Resin can reduce in volume as it hardens. Polypropylene (PP) in particular experiences a large volume loss upon hardening. If the resin's volume significantly reduces upon hardening, a depression may form on contact surface 22b of inner barrel 22. In this case, a gap may form between the contact surface and the cover member in the immersed state, and this gap may connect the storage space to the outside of the inner barrel, potentially compromising the airtightness of the storage space. If the airtightness of the storage space is impaired, the ink in the nib housed in the storage space will dry and harden, preventing writing with the writing instrument.

[0046] In this embodiment, because contact surface 22b includes annular rib 83, when the resin in the mold hardens, annular rib 83, which has a relatively small volume, hardens first, followed by the main body of inner shaft 22. In this case, because annular rib 83 has already hardened by the time the main body of inner shaft 22 hardens, deformation of annular rib 83 due to a decrease in the volume of resin is suppressed. This suppresses the occurrence of a gap between annular rib 83 and cover member 72 in the immersed state. Therefore, a decrease in the airtightness of storage space S can be effectively suppressed.

[0047] The width W of the annular rib 83 may be 0.2 mm or more and 2.0 mm or less (see FIG. 5). The width W is the maximum dimension of the annular rib 83 measured in a direction parallel to the top surface 85 and perpendicular to the direction in which the annular rib 83 extends. When the width W is 0.2 mm or more, the strength of the annular rib 83 can be sufficiently ensured. Furthermore, when the width W is 2.0 mm or less, the volume of the annular rib 83 can be reduced, so that when the resin that makes up the inner shaft 22 hardens, the annular rib 83 can harden sufficiently faster than the main body of the inner shaft 22.

[0048] The height H of the annular rib 83 may be 0.1 mm or more and 2.0 mm or less (see FIG. 6). The height H is the maximum dimension of the annular rib 83 measured along a direction perpendicular to the top surface 85. When the height H is 0.1 mm or more, the top surface 85 is spaced apart from the contact surface 22b, and therefore the top surface 85 cools quickly when the resin hardens. Therefore, when the resin constituting the inner shaft 22 hardens, the top surface 85 can harden sufficiently faster than the main body of the inner shaft 22. Furthermore, when the height H is 2.0 mm or less, buckling of the annular rib 83 due to the elastic force of the elastic member 76 in the immersed state can be suppressed.

[0049] The operations of the retractable mechanism 40 and the sealing mechanism 70 will be described with reference to FIGS.

[0050] When the user presses the knock member 50 forward in the immersed state (FIG. 1), the writing member 12 moves forward via the rotating cam member 60. As the writing member 12 moves forward, the pen tip 13 pushes the cover member 72 forward against the resilient force of the resilient member 76, thereby opening the cover member 72. As the writing member 12 moves forward further, the pen tip 13 protrudes forward from the front end opening 20a. Even when the forward pressure of the knock member 50 is released, the writing member 12 maintains a state in which the pen tip 13 protrudes forward from the front end opening 20a. This causes the writing instrument 10 to transition from the immersed state to the protruding state.

[0051] Furthermore, when the user presses the knock member 50 forward in the extended state (FIG. 2), the writing member 12 moves a small distance forward. When the forward pressure on the knock member 50 is released, the resilient force of the first resilient member 42 moves the writing member 12 rearward, and the nib 13 retracts from the front-end opening 20a. As the writing member 12 further moves rearward, the nib 13 is accommodated within the storage space S, and the resilient force of the resilient member 76 causes the cover member 72 to rotate toward the contact surface 22b (annular rib 83) of the barrel 20 (inner shaft 22). The opposing surface 74 of the cover member 72 then contacts the annular rib 83 of the contact surface 22b. This closes the opening 22a of the barrel 20 (inner shaft 22) with the cover member 72, sealing the storage space S. Sealing the storage space S prevents ink from drying out on the nib 13 in the retracted state.

[0052] The writing instrument 10 of this embodiment is a writing instrument 10 comprising a barrel 20 having an opening 22a, a writing member 12 having a nib 13, a retraction mechanism 40 that causes the nib 13 to protrude and retract from the opening 22a, and a sealing mechanism 70 that seals the storage space S for the nib 13 when the nib 13 is retracted, and the sealing mechanism 70 has an annular rib 83 formed to surround the opening 22a, and a cover member 72 that can contact the annular rib 83 to close the opening 22a.

[0053] In this writing instrument 10, because contact surface 22b includes annular rib 83, when the resin in the mold hardens during injection molding, annular rib 83, which has a relatively small volume, hardens first, followed by the main body of inner barrel 22. In this case, because annular rib 83 has already hardened by the time the main body of inner barrel 22 hardens, deformation of annular rib 83 due to a decrease in resin volume is suppressed. This suppresses the occurrence of a gap between annular rib 83 and lid member 72 in the sunk state. Therefore, a decrease in the airtightness of storage space S can be effectively suppressed.

[0054] In the writing instrument 10 of this embodiment, the annular rib 83 has a top surface 85, which is flat.

[0055] With such a writing instrument 10, when the opposing surface 74 of the cover member 72 and the top surface 85 of the annular rib 83 come into contact with each other, the opposing surface 74 and the top surface 85 come into surface contact with each other, effectively preventing air from passing through this contact area.

[0056] Next, a modified example of this embodiment will be described. In the following description and the drawings used in the following description, parts that can be configured similarly to the above-described embodiment will be designated by the same reference numerals as those used for the corresponding parts in the above-described embodiment, and duplicated descriptions will be omitted.

[0057] FIG. 7 shows a modified example of the inner shaft 22. Ink that has flowed out from the pen tip 13 may adhere to the top surface 85 of the annular rib 83 for some reason. The ink that has adhered to the top surface 85 dries and hardens on the top surface 85. This causes unevenness on the top surface 85 due to the hardened ink. As a result, a gap is created between the annular rib 83 and the lid member 72 in the immersed state. This may reduce the airtightness of the storage space S.

[0058] In this modified example, the inner shaft 22 has at least one groove 89 that communicates with the top surface 85. The groove 89 has the function of guiding ink adhering to the top surface 85 of the annular rib 83 and removing the ink from the top surface 85. In the example shown in FIG. 7, the inner shaft 22 has multiple grooves 89. The grooves 89 open to the top surface 85 and extend through the side surfaces 87 of the annular rib 83 to the base surface 81. In particular, the grooves 89 extend to the outer periphery of the base surface 81. However, the grooves 89 may extend partway through the base surface 81.

[0059] The grooves 89 extend linearly when viewed in a direction perpendicular to the top surface 85. However, the grooves 89 may extend in other shapes, such as curved or broken lines. When viewed in a direction perpendicular to the top surface 85, the grooves 89 extend radially from the opening 22a. In addition to the grooves (first grooves) 89 extending radially from the opening 22a, the inner shaft 22 may have additional grooves (second grooves) that communicate with the first grooves 89 and extend in the circumferential direction. This second groove may be formed on the base surface 81. The grooves 89 may guide ink using capillary force (capillary phenomenon).

[0060] The width of groove 89 may be 0.1 mm or more and 1.0 mm or less. The width of groove 89 is the maximum dimension of groove 89 measured in a direction parallel to top surface 85 and perpendicular to the direction in which groove 89 extends. When groove 89 has a width of 0.1 mm or more, a sufficient flow rate of ink flowing through groove 89 can be ensured. Furthermore, when groove 89 has a width of 1.0 mm or less, a sufficient capillary force can be generated in the ink located in groove 89.

[0061] The depth of groove portion 89 may be 0.1 mm or more and 3.0 mm or less. The depth of groove portion 89 is the maximum dimension of groove portion 89 measured along a direction perpendicular to top surface 85. When the depth of groove portion 89 is 0.1 mm or more, a sufficient flow rate of ink flowing through groove portion 89 can be ensured. Furthermore, when the depth of groove portion 89 is 3.0 mm or less, a decrease in the strength of inner shaft 22 due to the presence of groove portion 89 can be suppressed.

[0062] The writing instrument 10 of this modified example has at least one groove 89 that communicates with the top surface 85 .

[0063] In the writing instrument 10 of this modified example, the sealing mechanism 70 has a base surface 81 surrounding an annular rib 83, and a groove 89 is provided from the top surface 85 to the base surface 81.

[0064] With this writing instrument 10, ink adhering to the top surface 85 of the annular rib 83 can be guided and removed from the top surface 85. This prevents the top surface 85 from becoming uneven due to hardened ink. Therefore, the formation of a gap between the annular rib 83 and the lid member 72 in the immersed state is prevented. As a result, the deterioration of the sealing ability of the storage space S can be effectively prevented.

[0065] As another modification, the occurrence of unevenness on the top surface 85 may be suppressed by adjusting the wettability of the ink on the contact surface 22b. Specifically, the wettability of the ink on the contact surface 22b can be evaluated by the contact angle between the contact surface 22b and the ink. However, the contact angle between the contact surface 22b and the ink may vary depending on the type of ink. In this regard, the inventors of the present application have found that, when it is assumed that a water-based ink is to be used, it is possible to evaluate the wettability of the ink on the contact surface 22b by measuring the contact angle between the contact surface 22b and water.

[0066] The contact angle between top surface 85 and water may be greater than 0 degrees and less than or equal to 90 degrees. In this case, top surface 85 becomes more hydrophilic. The contact angle is measured in accordance with "6. Sessile Drop Method" of JIS R 3257:1999 (Test Method for Wettability of Substrate Glass Surfaces). When measuring the contact angle, the contact angles are measured at five points sufficiently distant from each other so as to reflect the contact angle of the entire surface to be measured, and the arithmetic mean value is taken as the contact angle on that surface.

[0067] Since the contact angle between top surface 85 and water is 90 degrees or less, ink adhering to top surface 85 easily spreads over top surface 85. Therefore, even if ink adhering to top surface 85 dries and hardens, the occurrence of unevenness on top surface 85 due to the hardened ink is suppressed. This suppresses the occurrence of a gap between annular rib 83 and lid member 72 in the immersed state. Therefore, a decrease in the airtightness of storage space S can be effectively suppressed.

[0068] The contact angle between a specific surface and water can be adjusted by the surface roughness of that surface. Examples of the specific surface include the top surface 85, the side surface 87, and the base surface 81. The surface roughness of the specific surface can be adjusted by the roughness imparted to the inner surface of the mold when manufacturing the inner shaft 22. The arithmetic mean roughness (Ra) of the top surface 85 may be 0.012 μm or more and 6.3 μm or less. When measuring the arithmetic mean roughness (Ra), the arithmetic mean roughness (Ra) is measured at five points that are sufficiently spaced apart so as to reflect the roughness of the entire surface to be measured, and the arithmetic mean value is defined as the arithmetic mean roughness (Ra) of the surface.

[0069] In the writing instrument 10 of this modified example, the contact angle between the top surface 85 and water is 90 degrees or less.

[0070] With this writing instrument 10, ink adhering to the top surface 85 easily spreads over the top surface 85. Therefore, even if the ink adhering to the top surface 85 dries and hardens, the occurrence of unevenness on the top surface 85 due to the hardened ink is suppressed. This suppresses the occurrence of a gap between the annular rib 83 and the lid member 72 in the immersed state. Therefore, the deterioration of the sealing ability of the storage space S can be effectively suppressed.

[0071] In this modified example, the technique of providing the groove 89 in the inner shaft 22, which was described with reference to FIG. 7, may also be employed.

[0072] As yet another modification, the contact angle between the base surface 81 and water may be smaller than the contact angle between the top surface 85 and water. In this case, the hydrophilicity of the base surface 81 is greater than the hydrophilicity of the top surface 85. In other words, the ink wets and spreads more easily on the base surface 81 than on the top surface 85. Therefore, ink adhering to the top surface 85 is pulled by the base surface 81 and is more likely to be removed from the top surface 85.

[0073] For example, the contact angle between the top surface 85 and water and the contact angle between the side surface 87 and water may be equal to each other. In this case, the contact angle between the base surface 81 and water is smaller than the contact angle between the top surface 85 and water and the contact angle between the side surface 87 and water. In this case, the hydrophilicity of the base surface 81 is greater than the hydrophilicity of the top surface 85 and the side surface 87, so that ink adhering to the top surface 85 and the side surface 87 is pulled by the base surface 81 and removed.

[0074] In this case, the difference between the contact angle between base surface 81 and water, and the contact angle between top surface 85 and water and the contact angle between side surface 87 and water may be 1.0 degree or more. This makes the hydrophilicity of base surface 81 much greater than the hydrophilicity of top surface 85 and side surface 87, so that ink adhering to top surface 85 and side surface 87 is pulled by base surface 81 and more appropriately removed.

[0075] Furthermore, the contact angle between the side surface 87 and water and the contact angle between the base surface 81 and water may be set equal to each other. In this case, the contact angle between the side surface 87 and water and the contact angle between the base surface 81 and water are smaller than the contact angle between the top surface 85 and water. In this case, the hydrophilicity of the side surface 87 and the base surface 81 is greater than the hydrophilicity of the top surface 85, so that ink adhering to the top surface 85 is removed while being pulled by the side surface 87 and the base surface 81.

[0076] Furthermore, the contact angle between top surface 85 and water, the contact angle between side surface 87 and water, and the contact angle between base surface 81 and water may be set to decrease in this order. In this case, the contact angle between side surface 87 and water is smaller than the contact angle between top surface 85 and water, and the contact angle between base surface 81 and water is smaller than the contact angle between side surface 87 and water. In this case, the hydrophilicity of side surface 87 is greater than that of top surface 85, and the hydrophilicity of base surface 81 is greater than that of side surface 87, so that ink adhering to top surface 85 is first pulled by side surface 87 and then further pulled by base surface 81, thereby being removed.

[0077] In this case, the difference between the contact angle between the side surface 87 and water and the contact angle between the top surface 85 and water may be 1.0 degree or more. Furthermore, the difference between the contact angle between the base surface 81 and water and the contact angle between the side surface 87 and water may be 1.0 degree or more. This makes the hydrophilicity of the side surface 87 sufficiently greater than that of the top surface 85, and also makes the hydrophilicity of the base surface 81 sufficiently greater than that of the side surface 87, so that ink adhering to the top surface 85 is pulled by the side surface 87 and then further pulled by the base surface 81, thereby being more appropriately removed.

[0078] In this modified writing instrument 10, the sealing mechanism 70 has a base surface 81 surrounding an annular rib 83, and the contact angle between the base surface 81 and water is smaller than the contact angle between the top surface 85 and water.

[0079] With this writing instrument 10, the base surface 81 is more hydrophilic than the top surface 85. That is, ink spreads more easily on the base surface 81 than on the top surface 85. Therefore, ink adhering to the top surface 85 is pulled by the base surface 81 and is more likely to be removed from the top surface 85. [Explanation of symbols]

[0080] 10 Writing instruments 12 Writing materials 13 Pen tip 15 Storage tube 17 First Receiving Section 19 Protrusion 20 shaft cylinder 20a Front end opening 21 Front axle 22 Inner shaft 22a opening 22b Contact surface 24 Groove 25 Outer shaft 26 First connecting member 28 Second Receiving Section 29 Recess 30 Tip member 31 rear axle 32 Inner shaft 35 Outer shaft 36 Second connecting member 38 Head crown 40 Appearance mechanism 42 First spring element 44 Second spring element 50 Knock member 52 Operation section 54 Expanded diameter part 56 Hole 58 Inward protrusion 59 O-ring 60 Rotating cam member 62 Rear protrusion 64 Engagement part 70 Sealing mechanism 72 Lid member 74 Opposite Surface 76 Elastic members 78 pins 81 Base surface 83 Annular rib 85 Top surface 87 Side 89 Groove da axial direction A Center axis S Storage space

Claims

1. A writing implement comprising: a barrel having an opening; a writing member having a pen tip; a retraction mechanism for retracting the pen tip from the opening; and a sealing mechanism for sealing an accommodation space for the pen tip when the pen tip is retracted, The sealing mechanism includes: an annular rib formed to surround the opening; a cover member that can contact the annular rib to close the opening; A writing instrument having:

2. the annular rib has a top surface; The writing instrument of claim 1 , wherein the top surface is flat.

3. The writing implement according to claim 2 , further comprising at least one groove communicating with said top surface.

4. the sealing mechanism has a base surface surrounding the annular rib; The writing implement according to claim 3 , wherein the groove portion is provided from the top surface to the base surface.

5. The writing instrument of claim 2 , wherein the contact angle between the top surface and water is 90 degrees or less.

6. the sealing mechanism has a base surface surrounding the annular rib; The writing instrument of claim 2 , wherein the contact angle between the base surface and water is smaller than the contact angle between the top surface and water.

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