Writing implement

Abstract

A writing implement (10) comprises a barrel (20) having an opening portion (22a), a writing member (12) having a pen tip (13), an extension / retraction mechanism (40) for causing the pen tip (13) to extend and retract through the opening portion (22a), and a sealing mechanism (70) for sealing an accommodating space for the pen tip (13) when the pen tip (13) is retracted, wherein: the barrel (20) includes a front shaft (21), and a rear shaft (31) that is attached to the front shaft (21) from the rear; the front shaft (21) includes an inner shaft (22) made of polypropylene, an outer shaft (25) disposed outside the inner shaft (22), and a connecting member (26) that is connected to the rear shaft (31); the inner shaft (22) is mechanically fixed to the connecting member (26); and the outer shaft (25) is joined to the connecting member (26) by means of an adhesive (Ad).

Description

writing implements

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

[0002] A writing instrument is known that includes a barrel, a writing element having a nib, and a retraction mechanism for extending and retracting the nib from the barrel. In addition, in such a writing instrument, the nib storage space is sealed when the nib is retracted to prevent ink from drying out at the nib.

[0003] JP2007-112032A discloses a writing instrument comprising 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.

[0004] The present inventors conducted further research into such writing instruments and discovered that moisture evaporated from ink not only leaks through gaps between components, such as the gap between the barrel and the lid, but can also leak through the material that makes up the barrel itself. Therefore, the present inventors considered using polypropylene (PP), which has low water vapor permeability, as the barrel material to reduce moisture leakage through the barrel material itself. However, polypropylene is difficult to secure to other components with adhesives. In this case, it is particularly difficult to secure the inner shaft, made of polypropylene, to the outer shaft with adhesives when the barrel has a dual structure consisting of an inner shaft and an outer shaft.

[0005] The present invention has been made in consideration of these points, and aims to appropriately fix the inner shaft to the outer shaft even when polypropylene is used as the material for forming the inner shaft.

[0006] The writing instrument according to the present invention is: <Aspect 1> A writing instrument comprising a barrel having an opening, a writing member having a nib, a retraction mechanism for causing the nib to protrude and retract from the opening, and a sealing mechanism for sealing the nib storage space when the nib is retracted, wherein the barrel includes a front barrel and a rear barrel attached to the front barrel from the rear, the front barrel includes an inner barrel made of polypropylene, an outer barrel positioned outside the inner barrel, and a connecting member connected to the rear barrel, the inner barrel is mechanically fixed to the connecting member, and the outer barrel is bonded to the connecting member with an adhesive.

[0007] The writing instrument according to the present invention relates to: <Aspect 2> The writing instrument according to Aspect 1, in which there is no part joined with an adhesive between the inner shaft and the outer shaft.

[0008] The writing instrument according to the present invention relates to: <Aspect 3> The writing instrument according to Aspect 1 or 2, wherein a step is formed between the outer surface of the inner shaft and the outer surface of the connecting member.

[0009] The writing instrument according to the present invention relates to: <Aspect 4> The writing instrument according to any one of Aspects 1 to 3, wherein the connecting member is made of metal.

[0010] The writing instrument according to the present invention relates to: <Aspect 5> The writing instrument according to any one of Aspects 1 to 4, wherein the connecting member has a through hole extending in the radial direction, and a portion of the inner shaft is located within the through hole.

[0011] The writing instrument according to the present invention relates to: <Aspect 6> The writing instrument according to Aspect 5, wherein the connecting member has a plurality of the through holes arranged in the circumferential direction.

[0012] The writing instrument according to the present invention relates to: <Aspect 7> The writing instrument according to any one of Aspects 1 to 6, wherein the outer surface of the front portion of the inner barrel has a protrusion, and the protrusion is in contact with the inner surface of the outer barrel.

[0013] The writing instrument according to the present invention relates to: <Aspect 8> The writing instrument according to Aspect 7, wherein the inner shaft has a plurality of the protrusions arranged in the circumferential direction.

[0014] The writing instrument according to the present invention relates to: <Aspect 9> The writing instrument according to Aspect 7 or 8, in which the protrusion is a rib extending in the axial direction.

[0015] The writing instrument according to the present invention relates to: <Aspect 10> The writing instrument according to any one of Aspects 1 to 6, wherein the surface of the connecting member that faces the adhesive has an uneven portion.

[0016] A writing instrument according to the present invention relates to: <Aspect 11> The writing instrument according to any one of Aspects 1 to 10, further comprising a front seal portion that seals the space between the inner shaft and the outer shaft forward of the adhesive.

[0017] A writing instrument according to the present invention relates to: <Aspect 12> The writing instrument according to Aspect 11, wherein the front seal portion includes an annular protrusion formed on the outer peripheral surface of the inner shaft.

[0018] The writing instrument according to the present invention relates to: <Aspect 13> The writing instrument according to any one of Aspects 1 to 12, further comprising a rear seal portion that seals the space between the connecting member and the outer shaft rearward of the adhesive.

[0019] A writing instrument according to the present invention relates to: <Aspect 14> The writing instrument according to Aspect 13, wherein the rear seal portion includes an O-ring disposed between the connecting member and the outer shaft.

[0020] The writing instrument according to the present invention relates to: <Aspect 15> The writing instrument according to any one of Aspects 1 to 14, further comprising at least one annular groove formed on the inner circumferential surface of the connecting member, and a portion of the inner shaft is disposed inside the annular groove.

[0021] According to the present invention, even when polypropylene is used as the material for forming the inner shaft, the inner shaft can be appropriately fixed to the outer shaft.

[0022] FIG. 1 is a diagram for explaining one embodiment of the present invention, showing an example of a writing instrument in a retracted state. FIG. 2 is a longitudinal cross-sectional view showing the writing instrument of FIG. 1 in a retracted state. FIG. 3 is a longitudinal cross-sectional view showing the writing instrument of FIG. 1 in a protruding state. FIG. 4 is a longitudinal cross-sectional view showing an example of an inner shaft and a connecting member of a writing instrument. FIG. 5 is an enlarged view of a portion marked V in FIG. 1. FIG. 6 is an enlarged view of a portion marked VI in FIG. 1. FIG. 7 is a view showing one modified example of the inner shaft and connecting member. FIG. 8 is a view showing another modified example of the inner shaft and connecting member. FIG. 9 is a view showing yet another modified example of the inner shaft and connecting member. FIG. 10 is a view showing yet another modified example of the connecting member. FIG. 11 is a view showing yet another modified example of the connecting member. FIG. 12 is a view showing yet another modified example of the inner shaft and connecting member. FIG. 13 is an enlarged view of a portion marked XIII in FIG. 12. FIG. 14 is an enlarged view of a portion marked XIV in FIG. 12. Fig. 15 is a diagram showing yet another modified example of the inner shaft and the connecting member. Fig. 16 is an enlarged view of a portion designated XVI in Fig. 15. Fig. 17 is a longitudinal sectional view showing the connecting member of Fig. 15. Fig. 18 is a diagram showing yet another modified example of the inner shaft and the connecting member, showing a portion corresponding to Fig. 16. Fig. 19 is a longitudinal sectional view showing the connecting member of Fig. 18.

[0023] An embodiment of the present invention will be described below with reference to the drawings. In the drawings attached to this specification, the scale and aspect ratios of the actual objects have been appropriately changed and exaggerated for the sake of ease of illustration and understanding.

[0024] 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.

[0025] 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 pen tip side 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.

[0026] Fig. 1 is a diagram for explaining one embodiment of the present invention, showing an example of a writing instrument 10 in a retracted state. In Fig. 1, the outer shaft 25 of the barrel 20 is shown in a cross-sectional view cut along a plane passing through the central axis A. Fig. 2 is a vertical cross-sectional view showing the writing instrument 10 in a retracted state, and Fig. 3 is a vertical cross-sectional view showing the writing instrument 10 in a protruding state.

[0027] 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 forms handwriting 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, markers, etc. In this embodiment, an example will be 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 protrusion 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 resilient force of a first resilient member 42, which will be described later. The protrusion 19 protrudes radially outward from the main body of the writing element 12 .

[0028] The retraction 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.

[0029] 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, allowing the pen tip 13 to pass through. In this embodiment, the front end opening 20a is formed at the front end of the tip member 30.

[0030] 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. In this embodiment, front barrel 21 includes inner barrel 22, outer barrel 25 disposed radially outward from inner barrel 22, and first connecting member (connecting member) 26.

[0031] 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 protruding portion 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 protruding portion 19 of the writing member 12 within the groove 24, the writing member 12 is supported relative to the barrel 20 so that it can move in the axial direction da but cannot rotate circumferentially. An opening 22a is formed at the tip of the inner shaft 22, allowing the nib 13 of the writing member 12 to pass through.

[0032] Moisture evaporated from the ink can leak not only through gaps between components, such as the gap between the barrel 20 and the cover member 72, but can also leak through the material that makes up the barrel 20. Therefore, in this embodiment, polypropylene (PP), which has low water vapor permeability, is used as the material for the inner barrel 22. The inner barrel 22 may be manufactured by injection molding. This prevents moisture evaporated from the ink from leaking through the material that makes up the inner barrel 22. This prevents the ink from drying out on the writing member 12.

[0033] The outer shaft 25 is a component that is visible to the user and is also a component that the user grasps with their fingers when writing with the writing instrument 10. Therefore, the outer shaft 25 is formed from an appropriate material, taking into consideration design and ease of holding by the user. For example, the outer shaft 25 may be formed from resin, elastomer, metal, wood, etc. When the outer shaft 25 is formed from resin, it is preferable to use a material other than polypropylene as the resin.

[0034] The first connecting member (connecting member) 26 is a member that constitutes a connecting portion with the rear shaft 31. The first connecting member 26 is fixed to the rear end of the inner shaft 22 and the rear end of the outer shaft 25. The first connecting member 26 is formed, for example, from resin, metal, or the like. When the first connecting member 26 is formed from resin, it is preferable to use a material other than polypropylene as the resin. In particular, from the viewpoint of ensuring sufficient strength, it is preferable that the first connecting member 26 be formed from metal. In this embodiment, the inner shaft 22 is mechanically fixed to the first connecting member 26. Furthermore, the outer shaft 25 is bonded to the first connecting member 26 with an adhesive Ad. Specific aspects of the fixation between the inner shaft 22 and the first connecting member 26 and the bonding between the outer shaft 25 and the first connecting member 26 will be described later.

[0035] Tip member 30 is a member that forms the tip portion of barrel 20. Tip member 30 functions to protect 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 through which nib 13 appears and disappears 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.

[0036] 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.

[0037] The inner shaft 32 is a member that houses the rear portion of the writing member 12. The inner shaft 32 is a member that has a generally cylindrical shape. The inner shaft 32 is formed, for example, from resin, metal, wood, etc. 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.

[0038] 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 axle 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 illustrated example is not limiting, 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 axle 31 may be formed integrally.

[0039] The extension / retraction mechanism 40 is a mechanism for alternately switching the writing instrument 10 between a protruding state and a retracted state. The extension / retraction 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.

[0040] 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 part of the extension / retraction mechanism 40 and also constitutes part of the sealing mechanism 70, as described below.

[0041] 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 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 does not slip out rearward from the rear end of the barrel 20.

[0042] 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 unable to rotate in the circumferential direction.

[0043] 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.

[0044] 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.

[0045] 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 engaging portion 64 of the rotating cam member 60 is engaged with the inward protruding portion 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.

[0046] 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 structure of the mechanism disclosed in Japanese Patent Application Laid-Open No. 2013-006281 can be used as these specific structures.

[0047] The writing instrument 10 of this embodiment has a sealing mechanism 70 that seals the storage space S for the nib 13. The sealing mechanism 70 seals the front end of the storage space S. The sealing mechanism 70 includes a barrel 20 (inner shaft 22), a cover member 72, a resilient member 76, and a pin 78.

[0048] The inner shaft 22 has an opening 22a through which the pen tip 13 can pass. A cover member 72 is attached to the inner shaft 22. A resilient member 76 biases the cover member 72 toward the opening 22a 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 in 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 FIGS. 2 and 3 , the pin 78 is inserted into a through-hole provided in the front end portion of the inner shaft 22. Furthermore, the pin 78 is inserted into an annular portion provided in 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 around the pin 78, closing or separating from the opening 22a. In other words, the pin 78 also serves as the rotation axis of the cover member 72. A gap 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.

[0049] 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 extended state, it allows the nib 13 to protrude. The cover member 72 is biased by the 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 cover member 72 to contact the front end surface of the inner shaft 22 and close the opening 22a. This seals the storage space S for the nib 13 (see FIG. 2). In this case, drying of the ink on the nib 13 is suppressed. When transitioning from the retracted state to the extended state, the nib 13 moves forward and pushes the cover member 72 forward, opening the cover member 72, and the nib 13 protrudes forward through the opening 22a and the front-end opening 20a (see FIG. 3). In this extended state, writing with the writing instrument 10 is possible.

[0050] Next, with reference to Figures 4 and 5, an example of a fixing mode between the inner shaft 22 and the first connecting member 26 and an example of a joining mode between the outer shaft 25 and the first connecting member 26 in the barrel tube 20 will be described. Figure 4 is a vertical cross-sectional view showing an example of the inner shaft 22 and the first connecting member 26 of the writing instrument 10. Figure 5 is an enlarged view of the portion marked V in Figure 1.

[0051] The inner shaft 22 is mechanically fixed to the first connecting member 26. Here, "mechanically fixed" refers to being fixed without using an adhesive. For example, "mechanically fixed" includes fixing by resin insert molding, fixing by fitting a convex portion into a concave portion or a hole, fixing by engagement between convex portions, fixing by press-fitting, etc.

[0052] In this embodiment, the first connecting member 26 has at least one through hole 26a extending radially. The first connecting member 26 may have a plurality of through holes 26a arranged circumferentially. In the example shown in FIG. 4 , the first connecting member 26 has two through holes 26a arranged circumferentially. The two through holes 26a are arranged at an angular interval of 180 degrees from each other around the central axis A. A portion of the inner shaft 22 is located within the through hole 26a. In the example shown in FIG. 4 , the first connecting member 26 having the through hole 26a is used as an insert component, and the polypropylene (PP) material constituting the inner shaft 22 is insert molded to fix the inner shaft 22 and the first connecting member 26 to each other. In this case, during the insert molding process, a fluid material flows into the through hole 26a and hardens, so that a portion of the inner shaft 22 is located within the through hole 26a. In particular, a portion of the inner shaft 22 fills the entire through hole 26a.

[0053] The outer shaft 25 is bonded to the first connecting member 26 with an adhesive Ad. In particular, a portion of the outer surface 26b of the first connecting member 26 is bonded to a portion of the inner surface 25b of the outer shaft 25 with the adhesive Ad. The adhesive Ad may be, for example, an acrylic adhesive or an epoxy adhesive. When the outer shaft 25 and the first connecting member 26 are both formed of a material other than polypropylene, the outer shaft 25 and the first connecting member 26 are appropriately bonded together with the adhesive Ad.

[0054] Furthermore, since it is difficult to properly bond inner shaft 22 made of polypropylene with adhesive Ad, it is preferable that there be no portion bonded with adhesive Ad between inner shaft 22 and outer shaft 25. This prevents an increase in the amount of adhesive Ad used and enables the weight of writing instrument 10 to be reduced. A step 21a may be formed between outer surface 22d of inner shaft 22 and outer surface 26b of first connecting member 26. At this step 21a, the outer diameter of first connecting member 26 may be larger than the outer diameter of inner shaft 22. Forming step 21a between outer surface 22d of inner shaft 22 and outer surface 26b of first connecting member 26 increases the gap between outer surface 22d of inner shaft 22 and outer surface 25b of outer shaft 25 in the forward portion of step 21a. Therefore, adhesive Ad is less likely to adhere to this portion.

[0055] In this embodiment, the inner shaft 22 made of polypropylene is mechanically fixed to the first connecting member 26, and the outer shaft 25 is bonded to the first connecting member 26 with an adhesive Ad. As a result, even when the inner shaft 22 made of polypropylene is used as the inner shaft 22, the inner shaft 22 can be appropriately fixed to the outer shaft 25 using the adhesive Ad.

[0056] Polypropylene is a relatively soft material. When assembling or separating the front axle 21 and the rear axle 31, the user rotates the front axle 21 and the rear axle 31 in opposite directions about the central axis A. In this embodiment, the circumferential force acting on the outer axle 25 at this time is transmitted to the first connecting member 26 via the adhesive Ad, and is not transmitted directly to the inner shaft 22. Therefore, the polypropylene inner shaft 22 is prevented from being twisted and deformed by the circumferential force acting when assembling or separating the front axle 21 and the rear axle 31.

[0057] Figure 6 is an enlarged view of a portion marked VI in Figure 1. The inner shaft 22 of this embodiment has a protrusion 27 on the outer surface 22d of the front portion 22e. The inner shaft 22 may have a plurality of protrusions 27 arranged in the circumferential direction. The protrusion 27 may be a rib extending in the axial direction da. In particular, the rib may extend linearly along the axial direction da. The protrusion 27 is in contact with the inner surface 25b of the outer shaft 25. The protrusion 27 may be press-fitted into the inner surface 25b of the outer shaft 25.

[0058] The rear portion of the inner shaft 22 and the rear portion of the outer shaft 25 are fixed to each other via the first connecting member 26 and the adhesive Ad. However, if a radial gap exists between the front portion 22e of the inner shaft 22 and the front portion of the outer shaft 25, rattle may occur between the inner shaft 22 and the outer shaft 25 when a user holds the outer shaft 25 and writes. In this embodiment, the protrusion 27 contacts the inner surface 25b of the outer shaft 25, thereby preventing rattle from occurring between the inner shaft 22 and the outer shaft 25. In particular, if the protrusion 27 is press-fitted into the inner surface 25b of the outer shaft 25, the inner shaft 22 and the outer shaft 25 are fixed to each other even at the front portion, thereby more effectively preventing rattle from occurring between the inner shaft 22 and the outer shaft 25. However, without being limited to this, the protrusion 27 may be configured so that the inner shaft 22 and the outer shaft 25 can rotate relative to each other about the central axis A.

[0059] The operation of the retractable mechanism 40 and the sealing mechanism 70 will be described with reference to FIGS.

[0060] When the user presses the knock member 50 forward in the retracted state ( FIG. 2 ), the writing member 12 moves forward via the rotating cam member 60. As the writing member 12 moves forward, the nib 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 further forward, the nib 13 protrudes forward from the front end opening 20 a. Even when the forward pressure of the knock member 50 is released, the writing member 12 maintains a state in which the nib 13 protrudes forward from the front end opening 20 a. This transitions the writing instrument 10 from the retracted state to the protruding state.

[0061] Furthermore, when the user presses the knock member 50 forward in the extended state ( FIG. 3 ), 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 housed within the storage space S, and the resilient force of the resilient member 76 causes the cover member 72 to rotate toward the front end surface of the barrel 20 (inner shaft 22). The cover member 72 then contacts the front end surface of the barrel 20 (inner shaft 22). 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. Furthermore, in this embodiment, since the inner shaft 22 is made of polypropylene, it is possible to prevent moisture evaporated from the ink from passing through the material that constitutes the inner shaft 22 itself and leaking to the outside.

[0062] The writing instrument 10 of this embodiment comprises 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 for the nib 13 when the nib 13 is retracted.The barrel 20 includes a front barrel 21 and a rear barrel 31 attached to the front barrel 21 from the rear.The front barrel 21 includes an inner barrel 22 made of polypropylene, an outer barrel 25 arranged outside the inner barrel 22, and a connecting member 26 that connects to the rear barrel 31.The inner barrel 22 is mechanically fixed to the connecting member 26, and the outer barrel 25 is joined to the connecting member 26 with adhesive Ad.

[0063] According to this writing instrument 10, the polypropylene inner shaft 22 is mechanically fixed to the first connecting member 26, and the outer shaft 25 is bonded to the first connecting member 26 with adhesive Ad. As a result, even when the polypropylene inner shaft 22 is used as the inner shaft 22, the inner shaft 22 can be appropriately fixed to the outer shaft 25 using adhesive Ad.

[0064] When assembling or separating front barrel 21 and rear barrel 31, the user rotates front barrel 21 and rear barrel 31 in opposite directions about central axis A. In this embodiment, the circumferential force acting on outer barrel 25 at this time is transmitted to first connecting member 26 via adhesive Ad, and is not transmitted directly to inner barrel 22. Therefore, with writing instrument 10 of this embodiment, twisting and deformation of polypropylene inner barrel 22 due to the circumferential force acting when assembling or separating front barrel 21 and rear barrel 31 is suppressed.

[0065] In the writing instrument 10 of this embodiment, there is no portion joined by adhesive Ad between the inner shaft 22 and the outer shaft 25 .

[0066] In the writing instrument 10 of this embodiment, a step 21 a is formed between the outer surface 22 d of the inner shaft 22 and the outer surface 26 b of the connecting member 26 .

[0067] According to such a writing instrument 10, it is possible to suppress an increase in the amount of adhesive Ad used, and also to make the writing instrument 10 lighter.

[0068] In the writing instrument 10 of this embodiment, the connecting member 26 is made of metal.

[0069] With this writing instrument 10, the strength of connecting member 26 is improved, and connecting member 26 is prevented from being deformed by the force acting in the circumferential direction when front barrel 21 and rear barrel 31 are assembled to or separated from each other. This prevents polypropylene inner barrel 22 from being twisted and deformed by the force acting in the circumferential direction.

[0070] In the writing instrument 10 of this embodiment, the connecting member 26 has a through hole 26a extending in the radial direction, and a portion of the inner shaft 22 is located within the through hole 26a.

[0071] In the writing instrument 10 of this embodiment, the connecting member 26 has a plurality of through holes 26a arranged in the circumferential direction.

[0072] According to this writing instrument 10, the inner shaft 22 and the connecting member 26 can be fixed to each other with a simple structure.

[0073] In the writing instrument 10 of this embodiment, the outer surface 22 d of the front portion 22 e of the inner shaft 22 has a protrusion 27 , which contacts the inner surface 25 b of the outer shaft 25 .

[0074] In the writing instrument 10 of this embodiment, the inner shaft 22 has a plurality of protrusions 27 arranged in the circumferential direction.

[0075] In the writing instrument 10 of this embodiment, the protrusion 27 is a rib extending in the axial direction da.

[0076] According to this writing instrument 10 , the protrusion 27 is in contact with the inner surface 25 b of the outer shaft 25 , so that rattle between the inner shaft 22 and the outer shaft 25 can be suppressed.

[0077] 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.

[0078] Fig. 7 is a diagram showing a modified example of the inner shaft 22 and the connecting member 26. Fig. 8 is a diagram showing another modified example of the inner shaft 22 and the connecting member 26.

[0079] 7 and 8, the first connecting member 26 has four through holes 26a arranged in the circumferential direction. The four through holes 26a are arranged at an angular pitch of 90 degrees from each other around the central axis A.

[0080] In the example shown in Fig. 7, the through-hole 26a has a rectangular shape when viewed from the radial direction. In the example shown in Fig. 8, the through-hole 26a has a circular shape when viewed from the radial direction. However, the shape is not limited to this, and the through-hole 26a may have other shapes such as a triangle, a pentagon, a hexagon, an octagon, or an ellipse when viewed from the radial direction.

[0081] 9 to 11 are diagrams illustrating yet another modified example of the connecting member 26. In the example illustrated in FIGS. 9 to 11, the surface of the connecting member 26 facing the adhesive Ad has an uneven portion 26c. In the example illustrated in FIG. 9, the surface of the connecting member 26 facing the adhesive Ad includes a plurality of grooves extending in the circumferential direction and arranged in the axial direction da. In the example illustrated in FIG. 10, the surface of the connecting member 26 facing the adhesive Ad includes a plurality of grooves extending in the axial direction da and arranged in the circumferential direction. In the example illustrated in FIG. 11, the surface of the connecting member 26 facing the adhesive Ad includes a plurality of grooves extending forward as they move toward one circumferential side and a plurality of grooves extending rearward as they move toward one circumferential side. Note that the specific configuration of the uneven portion 26c is not limited to the example illustrated in FIGS. 9 to 11.

[0082] In the writing instrument 10 of this modified example, the surface of the connecting member 26 that faces the adhesive Ad has an uneven portion 26c.

[0083] According to such a writing instrument 10, the surface area of ​​the surface of the connecting member 26 that faces the adhesive Ad can be increased, thereby improving the adhesive strength between the adhesive Ad and the connecting member 26.

[0084] Fig. 12 is a diagram showing yet another modified example of the inner shaft 22 and the connecting member 26. Fig. 13 is an enlarged view of a portion marked XIII in Fig. 12. Fig. 14 is an enlarged view of a portion marked XIV in Fig. 12.

[0085] Through investigations by the present inventors, it was found that in a writing instrument 10 having an inner shaft 22 mechanically fixed to a connecting member 26, a small gap may form between the inner shaft 22 and the connecting member 26. If a gap forms between the inner shaft 22 and the connecting member 26, moisture evaporated from the ink may leak to the outside through this gap, causing the pen tip 13 to dry out.

[0086] The adhesive Ad that bonds the outer shaft 25 and the connecting member 26 together also functions as a sealing member that seals out moisture that leaks from a gap between the inner shaft 22 and the connecting member 26. On the other hand, the adhesive Ad does not adhere well to the polypropylene inner shaft 22, and a small gap may form between the inner shaft 22 and the adhesive Ad. In this case, there is a risk that moisture evaporated from the ink may leak to the outside through this gap.

[0087] In this modified example, writing instrument 10 includes a front seal portion 82 and a rear seal portion 86. Front seal portion 82 functions to seal the space between inner shaft 22 and outer shaft 25 forward of adhesive Ad. In this modified example, front seal portion 82 includes an annular protrusion 83 formed on the outer peripheral surface of inner shaft 22. Protrusion 83 extends annularly without interruption in the circumferential direction. When inner shaft 22 is disposed within outer shaft 25, protrusion 83 contacts the inner peripheral surface of outer shaft 25. In particular, protrusion 83 contacts the inner peripheral surface of outer shaft 25 over the entire circumference. This seals the space between inner shaft 22 and outer shaft 25 with protrusion 83. Therefore, even if moisture evaporated from the ink leaks from the gap between inner shaft 22 and connecting member 26, this moisture can be prevented from leaking forward through the space between inner shaft 22 and outer shaft 25.

[0088] The maximum diameter of the protrusion 83 may be slightly larger than the inner diameter of the portion of the inner circumferential surface of the outer shaft 25 with which the protrusion 83 makes contact. In this case, with the inner shaft 22 disposed within the outer shaft 25, the protrusion 83 is pressed against the inner circumferential surface of the outer shaft 25. This allows the protrusion 83 to more appropriately seal the space between the inner shaft 22 and the outer shaft 25.

[0089] It should be noted that the front seal portion 82 is not limited to one that includes the protrusion 83. The front seal portion 82 may be realized by, for example, an O-ring disposed between the inner shaft 22 and the outer shaft 25.

[0090] The rear seal portion 86 functions to seal the space between the connecting member 26 and the outer shaft 25 rearward of the adhesive Ad. In this modification, the rear seal portion 86 includes an O-ring 87 disposed between the connecting member 26 and the outer shaft 25. An annular groove 26d is formed in the outer peripheral surface of the connecting member 26. The O-ring 87 is disposed in the groove 26d. The groove 26d and the O-ring 87 extend annularly without interruption in the circumferential direction. When the inner shaft 22 is disposed within the outer shaft 25, the O-ring 87 contacts the inner peripheral surface of the outer shaft 25 and the outer peripheral surface (groove 26d) of the connecting member 26. In particular, the O-ring 87 contacts the inner peripheral surface of the outer shaft 25 and the outer peripheral surface of the connecting member 26 over the entire circumference. As a result, the space between the connecting member 26 and the outer shaft 25 is sealed by the O-ring 87. Therefore, even if moisture evaporated from the ink leaks out from the gap between the inner shaft 22 and the connecting member 26, this moisture can be prevented from leaking rearward through the space between the connecting member 26 and the outer shaft 25.

[0091] The rear seal portion 86 is not limited to an O-ring, and may be realized by, for example, an annular protrusion formed on the connecting member 26 or the outer shaft 25.

[0092] In this modification, either the front seal portion 82 or the rear seal portion 86 may be omitted. That is, the writing instrument 10 may have only either the front seal portion 82 or the rear seal portion 86.

[0093] The writing instrument 10 of this modified example includes a front seal portion 82 that seals the space between the inner shaft 22 and the outer shaft 25 forward of the adhesive Ad.

[0094] According to this writing instrument 10, the space between inner shaft 22 and outer shaft 25 is sealed by front seal portion 82. Therefore, even if moisture evaporated from the ink leaks out through the gap between inner shaft 22 and connecting member 26, this moisture can be prevented from leaking forward through the space between inner shaft 22 and outer shaft 25.

[0095] In the writing instrument 10 of this modified example, the front seal portion 82 includes an annular protrusion 83 formed on the outer circumferential surface of the inner shaft 22 .

[0096] According to this writing instrument 10, the front seal portion 82 can be formed with a simple structure.

[0097] The writing instrument 10 of this modified example includes a rear seal portion 86 that seals the space between the connecting member 26 and the outer shaft 25 behind the adhesive Ad.

[0098] In this writing instrument 10, the space between connecting member 26 and outer shaft 25 is sealed by rear seal portion 86. Therefore, even if water evaporated from the ink leaks out through the gap between inner shaft 22 and connecting member 26, this water can be prevented from leaking rearward through the space between connecting member 26 and outer shaft 25.

[0099] In the writing instrument 10 of this modified example, the rear seal portion 86 includes an O-ring 87 disposed between the connecting member 26 and the outer shaft 25 .

[0100] According to this writing instrument 10, the O-ring 87 can more firmly seal the space between the connecting member 26 and the outer shaft 25.

[0101] Fig. 15 is a diagram showing yet another modified example of the inner shaft 22 and the connecting member 26. Fig. 16 is an enlarged view of the portion marked XVI in Fig. 15. Fig. 17 is a vertical cross-sectional view showing the connecting member 26 of this modified example.

[0102] In this modified example, the connecting member 26 has at least one annular groove 26f. The annular groove 26f is formed on the inner circumferential surface of the connecting member 26. The annular groove 26f extends annularly without interruption along the circumferential direction. The connecting member 26 may have multiple annular grooves 26f. As shown in FIG. 17 , the multiple annular grooves 26f are formed independently of one another. In particular, two annular grooves 26f adjacent to one another in the axial direction da are independent of one another.

[0103] In a longitudinal cross section passing through the axial direction da, the multiple annular grooves 26f may have the same shape and dimensions as one another. Furthermore, in a longitudinal cross section passing through the axial direction da, the multiple annular grooves 26f may differ from one another in at least one of their shapes and dimensions. In a longitudinal cross section passing through the axial direction da, the annular grooves 26f may have any shape, such as a polygonal shape such as a rectangle or a triangle, or a shape including a circular arc. The multiple annular grooves 26f may be arranged at equal pitches in the axial direction da. Furthermore, the pitch in the axial direction da of some of the multiple annular grooves 26f may be different from the pitch in the axial direction da of the other annular grooves 26f.

[0104] A portion of the inner shaft 22 is disposed inside the annular groove 26 f. For example, when the inner shaft 22 is manufactured by injection molding, a portion of the inner shaft 22 may flow into the annular groove 26 f, thereby disposing a portion of the inner shaft 22 inside the annular groove 26 f.

[0105] The writing instrument 10 of this modified example further includes at least one annular groove 26f formed in the inner circumferential surface of the connecting member 26, and a portion of the inner shaft 22 is disposed inside the annular groove 26f.

[0106] According to such a writing instrument 10, the contact area between the inner shaft 22 and the connecting member 26 is increased, so that the occurrence of a gap between the inner shaft 22 and the connecting member 26 can be suppressed.

[0107] Fig. 18 is a diagram showing yet another modified example of the inner shaft 22 and the connecting member 26, and shows the parts corresponding to Fig. 16. Fig. 19 is a vertical cross-sectional view showing the connecting member 26 of this modified example.

[0108] This modification is a further modification of the modification described with reference to Figures 15 to 17. In this modification, the multiple annular grooves 26f include a wide groove 26g and a narrow groove 26h. The wide groove 26g has a width greater than the width of the narrow groove 26h. Here, the widths of the annular grooves 26f, 26g, and 26h refer to the dimensions (maximum dimensions) of the grooves in the axial direction da. In this modification, the wide groove 26g and the narrow groove 26h are adjacent to each other in the axial direction da.

[0109] When manufacturing the inner shaft 22 by injection molding, the molten polypropylene shrinks as it hardens. This shrinkage is more pronounced in portions with relatively large dimensions. Therefore, in this modification, shrinkage during hardening occurs more significantly in the portion of the inner shaft 22 located within the wide groove 26g than in the portion of the inner shaft 22 located within the narrow groove 26h. In this case, the polypropylene shrinks more significantly in the portion of the inner shaft 22 located within the wide groove 26g, causing the narrow groove 26h adjacent to the wide groove 26g in the axial direction da to be drawn toward the wide groove 26g. At this time, the portion of the inner shaft 22 located within the narrow groove 26h is pressed against the side surface of the narrow groove 26h. This improves adhesion between the inner shaft 22 and the connecting member 26 within the narrow groove 26h. Therefore, the sealing performance between the inner shaft 22 and the connecting member 26 within the narrow groove 26h can be improved.

[0110] In the modified example described with reference to Figures 12 to 19, the connecting member 26 has the uneven portion 26c, as in the modified example described with reference to Figures 9 to 11. The uneven portion 26c of the connecting member 26 increases the surface area of ​​the face of the connecting member 26 that faces the adhesive Ad, thereby improving the adhesive strength between the adhesive Ad and the connecting member 26. As described above, the adhesive Ad that bonds the outer shaft 25 and the connecting member 26 to each other also functions as a sealing member that seals out moisture that leaks from a gap between the inner shaft 22 and the connecting member 26. When the connecting member 26 has the uneven portion 26c, the improved adhesive strength between the adhesive Ad and the connecting member 26 can prevent moisture that evaporates from the ink from leaking to the outside through a gap that may form between the adhesive Ad and the connecting member 26.

Claims

1. A writing instrument comprising a barrel having an opening, a writing element having a nib, a retraction mechanism for extending and retracting the nib from the opening, and a sealing mechanism for sealing the nib storage space when the nib is retracted, wherein the barrel includes a front barrel and a rear barrel attached to the front barrel from the rear, the front barrel includes an inner barrel made of polypropylene, an outer barrel positioned outside the inner barrel, and a connecting member connected to the rear barrel, the inner barrel is mechanically fixed to the connecting member, and the outer barrel is bonded to the connecting member with an adhesive.

2. The writing instrument according to claim 1, wherein there is no adhesive bonded portion between the inner shaft and the outer shaft.

3. The writing implement according to claim 1, wherein a step is formed between the outer surface of said inner shaft and the outer surface of said connecting member.

4. The writing instrument according to claim 1, wherein the connecting member is made of metal.

5. The writing instrument according to claim 1, wherein the connecting member has a through hole extending radially, and a portion of the inner shaft is located within the through hole.

6. The writing implement according to claim 5, wherein the connecting member has a plurality of the through holes arranged in the circumferential direction.

7. The writing instrument of claim 1, wherein the outer surface of the front portion of the inner barrel has a protrusion, the protrusion contacting the inner surface of the outer barrel.

8. The writing implement according to claim 7, wherein the inner shaft has a plurality of the protrusions arranged in the circumferential direction.

9. The writing implement according to claim 7 or 8, wherein the protrusion is a rib extending in the axial direction.

10. The writing implement according to claim 1, wherein the surface of the connecting member that faces the adhesive has an uneven portion.

11. The writing instrument according to claim 1, further comprising a front seal portion that seals the space between the inner shaft and the outer shaft ahead of the adhesive.

12. The writing instrument according to claim 11, wherein the front seal portion includes an annular protrusion formed on the outer circumferential surface of the inner shaft.

13. The writing instrument according to claim 1, further comprising a rear seal portion that seals the space between the connecting member and the outer shaft behind the adhesive.

14. The writing instrument according to claim 13, wherein the rear seal includes an O-ring disposed between the connecting member and the outer shaft.

15. The writing instrument according to claim 1, further comprising at least one annular groove formed in the inner peripheral surface of the connecting member, and a portion of the inner shaft is disposed within the annular groove.

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