Mechanical pencil

Abstract

To provide a mechanical pencil capable of advancing a writing lead only in a state where a cap is attached to the rear end of a barrel.SOLUTION: A lead advancing mechanism 2 has a cylindrical shape extending in the front-to-rear direction and includes a lead tank 21 in which a writing lead is stored, a lead chuck connected to the front end of the lead tank 21 and advancing the writing lead forward, a first biasing member that biases the lead tank 21 and the lead chuck toward the rear, and a knock button 25 provided at the rear end of the lead tank 21 and positioned within the rear end opening of the barrel 1. A rear end face 25a of the knock button 25 is positioned at the same position as a rear end face 1a of the barrel 1 in the front-to-rear direction or further forward than the rear end face 1a of the barrel 1. A cap 3 has an outer tube 31 extending in the front-to-rear direction and an inner tube 33 positioned inside the outer tube 31 and extending in the front-to-rear direction, and when the outer tube 31 is fitted into the barrel 1 from the rear, the inner tube 33 is inserted into the rear end opening of the barrel 1 so that the knock button 25 can be pushed forward.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a mechanical pencil. [Background technology]

[0002] Conventionally, mechanical pencils have been known that include a barrel that extends in the front-to-rear direction along a central axis, a lead-advancing mechanism provided inside the barrel, and a cylindrical cap into which the barrel is removably fitted (for example, Patent Document 1).

[0003] In this type of mechanical pencil, the cap is fitted to the front end of the barrel, so that the pointed guide pipe (tip pipe) through which the writing lead is inserted can be covered by the cap. In addition, if the user accidentally drops the mechanical pencil from a desk or the like, the cap protects the guide pipe and other parts.

[0004] In the cap-knock type mechanical pencil described in Patent Document 1, with the cap attached to the rear end of the barrel, a user can advance the writing lead by knocking the cap. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Utility Model Application Publication No. 1-70581 Summary of the Invention [Problem to be solved by the invention]

[0006] In the cap knock type mechanical pencil of Patent Document 1, even when the cap is not attached to the rear end of the barrel, the knock part of the knock pestle protrudes rearward from the rear barrel (barrel). Therefore, when the cap is fitted to the front end of the barrel and the knock part is knocked, the writing lead protrudes too far from the guide pipe and breaks inside the cap, or breaks when it comes into contact with the cap when the cap is removed.

[0007] An object of the present invention is to provide a mechanical pencil in which the lead can be advanced only when the cap is attached to the rear end of the barrel. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides the following means.

[0009] [First aspect of the present invention] The lead-advancing mechanism is provided with a barrel extending in the front-rear direction along a central axis, a lead-advancing mechanism provided inside the barrel, and a cylindrical cap into which the barrel is removably fitted. The lead-advancing mechanism is provided with a barrel extending in the front-rear direction, a lead tank having a writing lead stored therein, a lead chuck connected to a front end of the lead tank and advancing the writing lead forward, a first biasing member that biases the lead tank and the lead chuck rearward, and a second biasing member that is provided at the rear end of the lead tank and biases the barrel toward the rear. a knock button disposed within the opening, a rear end surface of the knock button being disposed at the same position as the rear end surface of the barrel in the front-to-rear direction or further forward than the rear end surface of the barrel, the cap having an outer tube extending in the front-to-rear direction and an inner tube disposed inside the outer tube and extending in the front-to-rear direction, when the outer tube is fitted into the barrel from the rear side, the inner tube is inserted into the rear end opening of the barrel, making it possible to push the knock button forward.

[0010] In the mechanical pencil of the present invention, when the cap is attached to the rear end of the barrel, the inner tube of the cap is inserted into the rear end opening of the barrel, making it possible to push the knock button forward by the inner tube.

[0011] On the other hand, when the cap is not attached to the rear end of the barrel, the knock button is housed within the rear end opening of the barrel, and the user cannot press the knock button by a normal knock operation. Specifically, the rear end face of the knock button is located at the same position as the rear end face of the barrel in the front-to-rear direction or further forward, and the knock button does not protrude rearward from the barrel.

[0012] Therefore, only when the cap is attached to the rear end of the barrel, the user can press the knock button through the cap and advance the writing lead. In other words, when the cap is fitted to the front end of the barrel or in other states other than when the cap is attached to the rear end of the barrel, the user cannot advance the writing lead by knocking. Therefore, the present invention prevents problems such as the writing lead protruding from the guide pipe breaking inside the cap or breaking when it comes into contact with the cap when it is removed, as in the conventional pen.

[0013] [Aspect 2 of the present invention] A mechanical pencil as described in aspect 1, wherein the barrel has a stopper protrusion protruding radially inward from the rear end opening of the barrel, and the inner tube has a locking protrusion that overcomes the stopper protrusion to the front when inserted into the rear end opening of the barrel and is locked by the stopper protrusion from the front.

[0014] In this case, when the cap is attached to the rear end of the barrel, the locking projection of the inner barrel overcomes the anti-slip projection protruding into the rear end opening of the barrel to the front and is disposed opposite the anti-slip projection from the front. In this state, when the user performs a knock operation to push the knock button forward through the cap and releases the push, the lead tank and the knock button move rearward due to the biasing force of the first biasing member, and the locking projection of the inner barrel pushed rearward by the knock button is locked from the front by the anti-slip projection of the barrel.

[0015] This allows the cap to be properly attached to the rear end of the barrel, and prevents the cap from accidentally falling off the rear end of the barrel. This improves the ease of use of the mechanical pencil, such as knocking.

[0016] [Embodiment 3 of the present invention] The mechanical pencil according to aspect 1 or 2, wherein the barrel has an anti-pullout protrusion protruding radially inward from a rear end opening of the barrel, the lead advancing mechanism has a second biasing member provided between the lead tank and the knock button and biasing the knock button toward the rear, and the knock button has a button locking portion that is engaged with the anti-pullout protrusion from the front side by the biasing force of the second biasing member.

[0017] In this case, in a state other than the state where the cap is attached to the rear end of the barrel (such as the state where the cap is attached to the front end of the barrel), the button locking portion of the knock button is maintained in contact with the retaining protrusion from the front side by the biasing force of the second biasing member. In other words, the state where the knock button is disposed at the retracted end position is stably maintained by the biasing force of the second biasing member.

[0018] This makes it possible to stably maintain, for example, the rear end face of the knock button at the same position as the rear end face of the barrel in the front-rear direction (the rear end faces are flush with each other), etc. The exterior design of the rear end portion of the mechanical pencil can be made to have an excellent aesthetic appearance.

[0019] [Embodiment 4 of the present invention] The mechanical pencil according to any one of aspects 1 to 3, wherein the lead tank has a stepped portion provided on a peripheral wall of the lead tank and facing toward the rear, and the stepped portion faces or comes into contact with a part of the knock button from the front side with a gap therebetween when the inner tube is inserted into the rear end opening of the barrel.

[0020] In this case, with the cap attached to the rear end of the barrel, the step of the lead tank faces or comes into contact with a part of the knock button (such as the front end of the knock button) from the front with a gap between them. In this state, when the user performs a knock operation to push the cap forward, this pushing force is efficiently transmitted from the knock button via the step to the lead tank, improving operability when advancing the writing lead.

[0021] [Embodiment 5 of the present invention] A mechanical pencil according to any one of aspects 1 to 4, wherein the inner tube can be contracted in diameter by elastic deformation, and when the outer tube is fitted into the barrel from the rear side, the inner tube is inserted into the rear end opening of the barrel while being contracted in diameter.

[0022] In this case, when the cap is attached to the rear end of the barrel, the inner tube is inserted into the rear end opening of the barrel while being elastically deformed to reduce its diameter. After insertion, the inner tube expands in diameter due to restoration deformation within the barrel, thereby maintaining the state in which the inner tube is inserted into the rear end opening of the barrel.

[0023] [Aspect 6 of the present invention] A mechanical pencil according to any one of aspects 1 to 5, wherein the inner tube is elastically deformable, and when the outer tube is fitted into the barrel from the front side, the inner tube faces or contacts the outer periphery of the front end of the barrel with a gap therebetween.

[0024] In this case, when the cap is attached to the barrel from the front side, the inner tube of the cap faces or comes into contact with the outer periphery of the front end of the barrel (for example, the outer periphery of the tapered barrel) with a gap therebetween. If the user accidentally drops the mechanical pencil from a desk or the like, the elastically deformable inner tube comes into contact with the outer periphery of the front end of the barrel, thereby providing the effect of mitigating the impact transmitted from the cap to the barrel. This makes it possible to prevent problems such as the front end of the barrel being damaged by an impact such as a drop, or the writing lead breaking within this front end.

[0025] [Seventh aspect of the present invention] 7. The mechanical pencil of claim 6, wherein the inner tube has a plurality of elastic pieces arranged in a circumferential direction around the central axis, and each of the elastic pieces is elastically deformable.

[0026] In this case, the above-mentioned effect of the elastic deformation of the inner cylinder is more stably achieved. Effect of the Invention

[0027] According to the mechanical pencil of the above aspect of the present invention, the writing lead can be advanced only in a state where the cap is attached to the rear end of the barrel. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a cross-sectional view (longitudinal cross-sectional view) showing a mechanical pencil according to the present embodiment, specifically showing a state in which a cap in a non-writing position is fitted onto a barrel from the front side. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a portion II in FIG. [Diagram 3] FIG. 3 is a cross-sectional view (longitudinal cross-sectional view) showing the cap of the mechanical pencil of the present embodiment. [Figure 4] FIG. 4 is a cross-sectional view (longitudinal cross-sectional view) showing the mechanical pencil of this embodiment, specifically showing a state in which the cap in a writing position is fitted onto the barrel from the rear side. [Diagram 5] FIG. 5 is an enlarged cross-sectional view of a portion V in FIG. [Figure 6] FIG. 6 is a cross-sectional view (longitudinal cross-sectional view) showing the mechanical pencil of this embodiment, specifically showing a state in which the user pushes the cap, which is fitted to the barrel from the rear side, forward to perform a knock operation. [Figure 7] FIG. 7 is an enlarged cross-sectional view of part VII in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] A mechanical pencil 10 according to an embodiment of the present invention will be described with reference to the drawings. The mechanical pencil 10 according to the present embodiment is a knock-type mechanical pencil with a cap, which may be referred to as a cap knock-type mechanical pencil or the like.

[0030] As shown in Fig. 1, the mechanical pencil 10 has a generally cylindrical shape centered on a central axis C. The mechanical pencil 10 includes a barrel 1 extending along the central axis C, a lead advancing mechanism 2 provided inside the barrel 1, and a cylindrical cap 3 into which the barrel 1 is detachably fitted. The barrel 1, the lead advancing mechanism 2, and the cap 3 are arranged coaxially with each other, with the central axis C as a common axis.

[0031] The definitions of the directions used in this embodiment will be described below. In this embodiment, the direction in which the central axis C of the mechanical pencil 10 extends, that is, the direction along the central axis C, is called the front-rear direction. In each figure, the front-rear direction corresponds to the Y-axis direction. In the front-rear direction, the front side corresponds to the -Y side, and the rear side corresponds to the +Y side. The front-rear direction may also be referred to as the axial direction. In this case, for example, the front side corresponds to one axial side, and the rear side corresponds to the other axial side.

[0032] The direction perpendicular to the central axis C is called the radial direction. Within the radial direction, the direction approaching the central axis C is called the radially inner direction, and the direction away from the central axis C is called the radially outer direction. Moreover, the direction going around the central axis C is called the circumferential direction.

[0033] Each component of the mechanical pencil 10 will now be described. The barrel 1 is tubular about a central axis C and extends in the front-rear direction. Specifically, the barrel 1 is substantially cylindrical. The barrel 1 has a peripheral wall 11 extending in the front-rear direction, a guide pipe 12 disposed at the front end of the peripheral wall 11, a core return stopper (not shown), a front protrusion 13, a guide protrusion 14, and a pull-out prevention protrusion 15.

[0034] The peripheral wall 11 has a generally cylindrical shape centered on the central axis C. The front end of the peripheral wall 11 has a tapered tube portion 11a whose diameter decreases toward the front, and a cylindrical portion 11b that is disposed rearward of the tapered tube portion 11a and has a generally constant diameter along the front-rear direction. A cylindrical portion 11c of the peripheral wall 11 that is disposed rearward of the front end has a generally constant diameter along the front-rear direction. The cylindrical portion 11c constitutes the portion of the peripheral wall 11 other than the front end.

[0035] The guide pipe 12 has a cylindrical shape centered on the central axis C and extends in the front-rear direction. The guide pipe 12 protrudes forward from the front end of the tapered tube portion 11a. A writing lead (not shown) is inserted inside the guide pipe 12. The writing lead is used for writing by being advanced a predetermined amount from the guide pipe 12 toward the front by the lead advancing mechanism 2.

[0036] Although not specifically shown, the lead detent portion has an annular shape centered on the central axis C, and is disposed adjacent to the guide pipe 12 on the rear side of the guide pipe 12. The lead detent portion is disposed inside the tapered tube portion 11a. The inner peripheral surface of the lead detent portion contacts the outer peripheral surface of the writing lead. The lead detent portion prevents the writing lead from slipping out (falling) from the guide pipe 12 when the lead chuck 22, which will be described later, expands in diameter and the lead chuck 22 releases its hold on the writing lead.

[0037] The front projection 13 is disposed at the front end (front portion) of the outer circumferential surface of the barrel 1. Specifically, the front projection 13 is disposed at the cylindrical portion 11b of the front end of the peripheral wall 11. The front projection 13 protrudes radially outward from the outer circumferential surface of the peripheral wall 11. The front projection 13 is in the form of a rib extending in the circumferential direction. In this embodiment, the front projection 13 is an annular rib extending all around the outer circumferential surface of the peripheral wall 11.

[0038] The guide protrusion 14 is disposed at the front end (front portion) of the outer circumferential surface of the barrel 1. The guide protrusion 14 is disposed rearward away from the front protrusion 13. The guide protrusion 14 protrudes radially outward from the outer circumferential surface of the peripheral wall 11. The guide protrusion 14 is in the form of a rib extending in the circumferential direction. In this embodiment, the guide protrusion 14 is an annular rib extending all around the outer circumferential surface of the peripheral wall 11. However, this is not limiting, and a plurality of guide protrusions 14 may be provided on the outer circumferential surface of the peripheral wall 11 at intervals from each other in the circumferential direction.

[0039] As shown in Figs. 1 and 2, the retaining projection 15 is disposed at the rear end (rear end opening) of the inner peripheral surface of the barrel 1. The retaining projection 15 protrudes radially inward from the rear end opening of the barrel 1. Specifically, the retaining projection 15 is disposed at the rear end of the cylindrical portion 11c of the peripheral wall 11. The retaining projection 15 protrudes radially inward from the inner peripheral surface of the peripheral wall 11. The retaining projection 15 is in the form of a rib extending in the circumferential direction. In this embodiment, the retaining projection 15 is an annular rib extending all around the inner peripheral surface of the peripheral wall 11. In this embodiment, the retaining projection 15 constitutes the inner peripheral portion of the rear end surface 1a of the barrel 1.

[0040] Although not shown, the barrel 1 may have a cylindrical barrel body extending in the front-rear direction, a cylindrical tail pipe detachably attached to the rear end of the barrel body by screwing or the like, and a tapered barrel ferrule detachably attached to the front end of the barrel body by screwing or the like. That is, the barrel 1 may be configured by combining a plurality of members. In this case, for example, the barrel body includes the cylindrical portion 11c of the peripheral wall 11 except for the rear end, and the rear portion of the cylindrical portion 11b. The tail pipe includes the rear end of the cylindrical portion 11c. The ferrule includes the front portion of the cylindrical portion 11b, the tapered barrel portion 11a, the guide pipe 12, and the core return stop portion. The barrel body and the tail pipe are made of, for example, resin. The portion of the ferrule other than the core return stop portion is made of, for example, metal.

[0041] In this way, the barrel 1 is configured so as to be separable into the barrel body, the tail cylinder, and the ferrule, which facilitates the manufacture and assembly of the mechanical pencil 10. Furthermore, by removing the tail cylinder from the barrel body, the knock button 25 can be removed from the lead tank 21, which will be described later, and writing lead can be easily inserted into the lead tank 21 (see FIG. 2).

[0042] The lead advancing mechanism 2 is disposed inside the barrel 1. The lead advancing mechanism 2 has a lead tank 21, a lead chuck 22, a first biasing member 23, a chuck ring 24, a knock button 25, and a second biasing member 26.

[0043] As shown in Fig. 1, the lead tank 21 has a tubular shape extending in the front-rear direction. The lead tank 21 has a substantially cylindrical shape centered on a central axis C. A writing lead (not shown) is stored inside the lead tank 21. As shown in Fig. 2, the rear end of the lead tank 21 is located forward of the rear end surface 1a of the barrel 1.

[0044] The lead tank 21 has a step 21a provided on the peripheral wall of the lead tank 21 and facing the rear side. The step 21a is disposed at the rear end of the outer circumferential surface of the lead tank 21. The step 21a is annular about the central axis C and has a planar shape extending in a direction perpendicular to the central axis C.

[0045] As shown in Fig. 1, the lead chuck 22 is connected to the front end of the lead tank 21. The lead chuck 22 is generally cylindrical about a central axis C and extends in the front-rear direction. The lead of the lead tank 21 is received and held inside the lead chuck 22. The lead chuck 22 is repeatedly expanded and contracted in diameter by being moved in the front-rear direction, thereby enabling the held writing lead to be advanced forward.

[0046] Specifically, as the lead chuck 22 moves forward and undergoes an enlarged deformation, the writing lead held by the lead chuck 22 moves forward together with the lead chuck 22 and is released near the forward end position of the lead chuck 22. In addition, as the lead chuck 22 moves rearward and undergoes a reduced diameter deformation, the writing lead is again held by the lead chuck 22 near the retracted end position of the lead chuck 22. By repeating such movements of advance, expansion, retreat, and contraction in sequence, the lead chuck 22 advances the writing lead forward.

[0047] The first biasing member 23 is disposed inside the front end portion of the barrel 1. The first biasing member 23 is, for example, a compression coil spring, and extends spirally about the central axis C. The first biasing member 23 biases the lead tank 21 and the lead chuck 22 rearward relative to the barrel 1.

[0048] The chuck ring 24 is disposed inside the front end portion of the barrel 1, and is located forward of the first biasing member 23. The chuck ring 24 is annular about the central axis C. The chuck ring 24 is fixed to the barrel 1. The core chuck 22 is inserted inside the chuck ring 24.

[0049] 1, the biasing force of the first biasing member 23 moves the lead tank 21 and the lead chuck 22 rearward, and when the lead chuck 22 is at the retreated end position of its front-to-rear stroke, the chuck ring 24 fits onto the front end of the lead chuck 22 and clamps the lead chuck 22 from the outside in the radial direction. This causes the lead chuck 22 to shrink and deform, holding the writing lead inside.

[0050] 6, when the user performs a knock operation against the biasing force of the first biasing member 23 and pushes the cap 3 forward, the lead tank 21 and the lead chuck 22 are pushed forward via the knock button 25, and the lead chuck 22 moves forward. When the lead chuck 22 reaches the forward end position of its stroke in the front-to-rear direction, the lead chuck 22 is released from its engagement with the chuck ring 24. This causes the lead chuck 22 to expand and deform, releasing the writing lead inside.

[0051] As shown in Fig. 2, the knock button 25 has a cylindrical shape centered on the central axis C and extends in the front-rear direction. Specifically, the knock button 25 has a cylindrical shape with an end. The knock button 25 is provided at the rear end of the lead tank 21 and disposed within the rear end opening of the barrel 1. The knock button 25 is housed within the rear end of the cylindrical portion 11c of the peripheral wall 11. The knock button 25 releasably blocks the rear end opening of the lead tank 21, i.e., the lead insertion port.

[0052] The rear end of the lead tank 21 is inserted into the front end opening of the peripheral wall of the knock button 25. The knock button 25 is movable in the front-rear direction relative to the barrel 1. Specifically, the state shown in Fig. 2 represents the rearmost position of the knock button 25 when it has moved all the way to the rear. From this state, the knock button 25 is movable forward relative to the barrel 1.

[0053] In addition, in FIG. 2, when the knock button 25 is located at the rearmost position, the front end portion (the front end surface of the peripheral wall) of the knock button 25 is located away from the step portion 21a of the lead tank 21 to the rear side.

[0054] The rear end surface 25a of the knock button 25 is disposed at the same position as the rear end surface 1a of the barrel 1 in the front-rear direction, or further forward than the rear end surface 1a of the barrel 1. Specifically, in this embodiment, the rear end surface 25a of the knock button 25 is the rear surface facing the rear of a pair of plate surfaces facing in the front-rear direction of the top wall of the knock button 25. In this embodiment, at the retracted end position of the knock button 25 shown in Fig. 2, the rear end surface 25a of the knock button 25 and the rear end surface 1a of the barrel 1 are disposed at the same position (i.e., flush) in the front-rear direction.

[0055] The knock button 25 has a button locking portion 25b. The button locking portion 25b is disposed at the rear end of the outer circumferential surface of the knock button 25. The button locking portion 25b protrudes radially outward from the peripheral wall of the knock button 25 and extends in the circumferential direction. The button locking portion 25b is an annular rib centered on the central axis C. When the knock button 25 is in the retracted end position shown in FIG. 2, the button locking portion 25b comes into contact with the retaining projection 15 of the barrel tube 1 from the front side.

[0056] The second urging member 26 is disposed inside the knock button 25. The second urging member 26 is, for example, a compression coil spring, and extends spirally around the central axis C. The second urging member 26 is provided between the lead tank 21 and the knock button 25. Specifically, the second urging member 26 is disposed between the rear end surface of the lead tank 21 and the top wall of the knock button 25 in the front-rear direction. The second urging member 26 urges the knock button 25 toward the rear side. The button locking portion 25b of the knock button 25 is locked to the anti-pullout protrusion 15 from the front side by the urging force of the second urging member 26.

[0057] 1 and 3, the cap 3 is tubular about a central axis C and extends in the front-rear direction. Specifically, the cap 3 is cylindrical with a bottom (top), and one of both ends in the front-rear direction is open and the other end is closed. The shaft tube 1 can be fitted inside the cap 3.

[0058] In this embodiment, one end of the cap 3 in the front-rear direction is called the open end and the other end is called the closed end. In the following description of the cap 3, the direction from the closed end to the open end in the front-rear direction may be called the open end side, and the direction from the open end to the closed end may be called the closed end side.

[0059] 1, in a position where the open end of the cap 3 faces the rear side (+Y side), the cap 3 can be fitted to the barrel 1 from the front side (-Y side). In this embodiment, the position where the open end of the cap 3 faces the rear side may be referred to as a "non-writing position" or a "non-writing position". In the non-writing position, the cap 3 is detachably fitted to the front end of the barrel 1.

[0060] 4, in a position where the open end of the cap 3 faces the front side (-Y side), the cap 3 can be fitted to the barrel 1 from the rear side (+Y side). In this embodiment, the position where the open end of the cap 3 faces the front side may be referred to as the "writing position" or "writing position". In the writing position, the cap 3 is detachably fitted to the rear end of the barrel 1.

[0061] As shown in FIG. 1 and FIG. 3, the cap 3 has an outer cylinder 31, a blocking wall 32, and an inner cylinder 33.

[0062] The outer tube 31 is tubular about a central axis C, and in this embodiment, is cylindrical. The outer tube 31 extends in the front-rear direction. The outer tube 31 is a tubular member that constitutes the main body of the cap 3. The shaft tube 1 is detachably fitted into the outer tube 31 from the open end side.

[0063] The outer tube 31 has a cap protrusion 31a. The cap protrusion 31a protrudes radially inward from the inner circumferential surface of the outer tube 31. In this embodiment, the cap protrusion 31a is disposed in a middle portion of the inner circumferential surface of the outer tube 31, which is located between the open end and the closed end in the front-rear direction. The cap protrusion 31a is in the form of a rib extending in the circumferential direction. In this embodiment, the cap protrusion 31a is an annular rib centered on the central axis C.

[0064] As shown in Fig. 1, when the cap 3 in the non-writing position is fitted to the front end of the barrel 1, the cap protrusion 31a comes into contact with the front protrusion 13 from the rear side and is locked. When the user moves the cap 3 forward relative to the barrel 1 with a force equal to or greater than a predetermined value, the cap protrusion 31a can move forward over the front protrusion 13. In other words, the locked state between the cap protrusion 31a and the front protrusion 13 can be released by the user's operation.

[0065] 1, when the cap 3 is fitted to the barrel 1 from the front side, the guide protrusions 14 of the barrel 1 contact the open end of the inner circumferential surface of the outer tube 31 from the radially inside, or face each other with a gap. The guide protrusions 14 make the attachment position of the cap 3 to the barrel 1 in the non-writing position more stable.

[0066] The blocking wall 32 is plate-shaped and connected to the blocked end of the outer cylinder 31. The blocking wall 32 blocks the blocked end of the outer cylinder 31. In this embodiment, the blocking wall 32 has a disk shape that extends in a direction perpendicular to the central axis C.

[0067] The inner cylinder 33 is disposed inside the outer cylinder 31. The inner cylinder 33 has a generally cylindrical shape centered on the central axis C. The inner cylinder 33 is disposed radially inward and spaced apart from the outer cylinder 31. The inner cylinder 33 extends in the front-rear direction from the blocking wall 32 toward the open end. The end of the inner cylinder 33 on the open end side is located closer to the closed end than the open end of the outer cylinder 31.

[0068] At least the end portion on the open end side of the inner tube 33 is elastically deformable. That is, the inner tube 33 is elastically deformable. Specifically, the inner tube 33 can be reduced in diameter by elastic deformation, and can be expanded in diameter by restoration deformation after elastic deformation.

[0069] As shown in Figure 3, the inner tube 33 has an inner tube main body 33a connected to the blocking wall 32, an elastic piece 33b extending from the inner tube main body 33a toward the opening end side and elastically deformable in the radial direction, and a locking protrusion 33c arranged at the end side of the opening end of the inner tube 33.

[0070] The inner cylinder body 33a has a cylindrical shape centered on a central axis C. The inner cylinder body 33a extends in the front-rear direction from the blocking wall 32 toward the open end side.

[0071] The elastic piece 33b protrudes from the end of the inner cylinder body 33a on the open end side toward the open end side. The elastic piece 33b extends in the front-rear direction. The elastic piece 33b is plate-shaped, and a pair of plate surfaces face in the radial direction. The elastic piece 33b has a cross-sectional shape perpendicular to the central axis C that is curved in a circular arc shape extending in the circumferential direction.

[0072] A plurality of elastic pieces 33b are provided on the inner cylinder 33 and aligned in the circumferential direction. The plurality of elastic pieces 33b are arranged at intervals in the circumferential direction. In this embodiment, four elastic pieces 33b are provided at equal intervals in the circumferential direction. Each of the elastic pieces 33b is (individually) elastically deformable.

[0073] The locking projection 33c protrudes radially outward from the outer circumferential surface of the inner tube 33. The locking projection 33c is disposed on a plate surface (outer surface) of the elastic piece 33b facing radially outward. The locking projection 33c is disposed on an end of the outer surface of the elastic piece 33b on the opening end side. The locking projection 33c is shaped like a rib extending in the circumferential direction. A plurality of the locking projections 33c are provided on the inner tube 33, lined up in the circumferential direction. Each locking projection 33c is provided on each elastic piece 33b.

[0074] 4 and 5 show the cap 3 in a writing position attached to the barrel 1 from the rear side. As shown in Fig. 4 and 5, when the outer barrel 31 is fitted to the barrel 1 from the rear side, the inner barrel 33 is inserted into the rear end opening of the barrel 1, and the knock button 25 can be pushed forward. Specifically, the end faces of the elastic pieces 33b of the inner barrel 33 facing the opening end side (front side) come into contact with the rear end face 25a of the knock button 25 from the rear side.

[0075] More specifically, when the outer tube 31 is fitted into the barrel 1 from the rear side, the inner tube 33 is inserted into the rear end opening of the barrel 1 while being reduced in diameter as a result of the elastic pieces 33b elastically deforming radially inward. When the inner tube 33 is inserted into the rear end opening of the barrel 1, the locking projection 33c of the inner tube 33 moves forward over the retaining projection 15 and is locked by the retaining projection 15 from the front side.

[0076] When the inner tube 33 is inserted into the rear end opening of the barrel 1, the step 21a of the lead tank 21 faces or comes into contact with a part of the knock button 25 (the front end of the knock button 25 in this embodiment) from the front side with a gap. In this embodiment, the step 21a comes into contact with the front end surface of the peripheral wall of the knock button 25 from the front side.

[0077] When the user performs a knock operation by pushing the cap 3 forward from this state, the knock button 25 pressed by the inner cylinder 33 moves forward, and the lead tank 21 and the lead chuck 22 pressed by the knock button 25 via the step portion 21a also move forward, as shown in Figures 6 and 7. This causes the lead advancing mechanism 2 to advance the writing lead forward.

[0078] When the user moves the cap 3 rearward relative to the barrel 1 with a force equal to or greater than a predetermined value, the elastic pieces 33b elastically deform and the inner barrel 33 contracts in diameter, allowing the locking protrusions 33c to move rearward over the retaining protrusions 15. This allows the user to remove the cap 3 from the rear end of the barrel 1.

[0079] 1, when the cap 3 in the non-writing position is attached to the barrel 1 from the front, that is, when the outer barrel 31 is fitted to the barrel 1 from the front, the inner barrel 33 faces or comes into contact with the outer periphery of the front end of the barrel 1 with a gap. Specifically, the end of the opening end side (rear side) of each elastic piece 33b of the inner barrel 33 faces or comes into contact with the outer periphery of the tapered barrel portion 11a of the barrel 1 with a gap. In this state, the guide pipe 12 is housed inside the inner barrel 33.

[0080] In the mechanical pencil 10 of this embodiment described above, when the cap 3 is attached to the rear end of the barrel 1, the inner tube 33 of the cap 3 is inserted into the rear end opening of the barrel 1, making it possible for the inner tube 33 to push the knock button 25 forward.

[0081] On the other hand, when the cap 3 is not attached to the rear end of the barrel 1 (see FIG. 2), the knock button 25 is housed in the rear end opening of the barrel 1, and the user cannot press the knock button 25 by a normal knock operation. Specifically, the rear end surface 25a of the knock button 25 is located at the same position as the rear end surface 1a of the barrel 1 in the front-to-rear direction or further forward than that, and the knock button 25 does not protrude rearward from the barrel 1.

[0082] Therefore, only when the cap 3 is attached to the rear end of the barrel 1 as shown in Fig. 5 etc., can the user push in the knock button 25 via the cap 3, and the writing lead be advanced. In other words, in a state other than when the cap 3 is attached to the rear end of the barrel 1, such as when the cap 3 is fitted to the front end of the barrel 1, the user cannot advance the writing lead by knocking. Therefore, according to this embodiment, problems such as the writing lead protruding long from the guide pipe breaking inside the cap, or breaking on contact with the cap when removing the cap, as in the conventional case, are suppressed.

[0083] In this embodiment, when the cap 3 is attached to the rear end of the barrel 1, the locking projection 33c of the inner barrel 33 passes over the retaining projection 15 protruding into the rear end opening of the barrel 1 to the front side, and is disposed opposite the retaining projection 15 from the front side. In this state, when the user performs a knock operation to push the knock button 25 forward through the cap 3, and releases the pushing, the lead tank 21 and the knock button 25 move rearward due to the biasing force of the first biasing member 23, and the locking projection 33c of the inner barrel 33 pushed rearward by the knock button 25 is locked to the retaining projection 15 of the barrel 1 from the front side.

[0084] This keeps the cap 3 attached to the rear end of the barrel 1 in a good condition, and prevents the cap 3 from accidentally falling off the rear end of the barrel 1. This makes it easier to operate the mechanical pencil 10, such as by knocking it.

[0085] In addition, in this embodiment, the lead advancing mechanism 2 has a second biasing member 26 provided between the lead tank 21 and the knock button 25, and the biasing force of the second biasing member 26 causes the button locking portion 25b of the knock button 25 to be locked to the anti-pullout protrusion 15 from the front side. In this case, in a state other than the state in which the cap 3 is attached to the rear end of the barrel 1 (such as a state in which the cap 3 is attached to the front end of the barrel 1), the button locking portion 25b of the knock button 25 is maintained in contact with the retaining projection 15 from the front side by the biasing force of the second biasing member 26. In other words, the state in which the knock button 25 is disposed at the retracted end position is stably maintained by the biasing force of the second biasing member 26.

[0086] Therefore, for example, it is possible to stably maintain a state in which the rear end surface 25a of the knock button 25 is disposed at the same position as the rear end surface 1a of the barrel 1 in the front-rear direction (a state in which the rear end surfaces 25a, 1a are flush with each other). The exterior design of the rear end portion of the mechanical pencil 10 can be made to have an excellent aesthetic appearance.

[0087] Furthermore, in this embodiment, with the cap 3 attached to the rear end of the barrel 1, the step 21a of the lead tank 21 faces or comes into contact with a part of the knock button 25 (the front end of the knock button 25 in this embodiment) from the front with a gap between them. In this state, when a user performs a knock operation to push the cap 3 forward, this pushing force is efficiently transmitted from the knock button 25 via the step 21a to the lead tank 21, improving operability when advancing the writing lead.

[0088] In this embodiment, when the cap 3 is attached to the rear end of the barrel 1, the inner tube 33 is inserted into the rear end opening of the barrel 1 while being reduced in diameter by elastic deformation. After insertion, the inner tube 33 expands in diameter by restoring deformation inside the barrel 1, thereby maintaining the state in which the inner tube 33 is inserted into the rear end opening of the barrel 1 in a good condition.

[0089] In this embodiment, when the cap 3 is attached to the barrel 1 from the front side, the inner tube 33 of the cap 3 faces or contacts the outer periphery of the front end of the barrel 1 (the outer periphery of the tapered barrel portion 11a in this embodiment) with a gap therebetween. In the event that the user accidentally drops the mechanical pencil 10 from a desk or the like, the elastically deformable inner tube 33 comes into contact with the outer periphery of the front end of the barrel 1, thereby providing an effect of mitigating the impact transmitted from the cap 3 to the barrel 1. This makes it possible to prevent problems such as the front end of the barrel 1 being damaged by an impact such as a drop, or the writing lead being broken within the front end.

[0090] In this embodiment, the inner cylinder 33 has a plurality of elastic pieces 33b arranged in the circumferential direction around the central axis C, and each of the elastic pieces 33b is elastically deformable. In this case, the above-mentioned effect of the elastic deformation of the inner cylinder 33 is more stably achieved.

[0091] The present invention is not limited to the above-described embodiment, and the configuration may be modified within the scope of the present invention, for example as described below.

[0092] In the above embodiment, an example has been given in which the rear end surface 25a of the knock button 25 and the rear end surface 1a of the barrel 1 are disposed at the same position (flush) in the front-rear direction at the retracted end position of the knock button 25 shown in Fig. 2, but this is not limiting. That is, at the retracted end position of the knock button 25, the rear end surface 25a of the knock button 25 may be disposed forward of the rear end surface 1a of the barrel 1. In this case, the second biasing member 26 may not be provided.

[0093] The present invention may be combined with the various configurations described in the above-mentioned embodiments and modifications, and may include additions, omissions, substitutions, and other modifications, without departing from the spirit of the present invention. The present invention is not limited to the above-mentioned embodiments, but is limited only by the claims. [Industrial Applicability]

[0094] According to the mechanical pencil of the present invention, the lead can be advanced only when the cap is attached to the rear end of the barrel. This prevents the lead protruding from the guide pipe from breaking inside the cap or from coming into contact with the cap when removing the cap. Therefore, the mechanical pencil has industrial applicability. [Explanation of symbols]

[0095] Reference Signs List 1... barrel, 1a... rear end surface of barrel, 2... lead advancing mechanism, 3... cap, 10... mechanical pencil, 15... anti-pullout projection, 21... lead tank, 21a... step, 22... lead chuck, 23... first urging member, 25... knock button, 25a... rear end surface of knock button, 25b... button locking portion, 26... second urging member, 31... outer barrel, 33... inner barrel, 33b... elastic piece, 33c... locking projection, C... central shaft

Claims

1. A shaft cylinder extending in the front-rear direction along a central axis; A core advancing mechanism provided inside the barrel; a cap having a cylindrical shape and into which the barrel is detachably fitted; The core advancing mechanism includes: A lead tank having a cylindrical shape extending in the front-rear direction and containing a writing lead therein; A lead chuck connected to a front end of the lead tank and adapted to advance the lead forward; A first biasing member that biases the lead tank and the lead chuck rearward; A knock button is provided at the rear end of the lead tank and is disposed within the rear end opening of the barrel, a rear end surface of the knock button is disposed at the same position as a rear end surface of the barrel in the front-rear direction or forward of the rear end surface of the barrel, The cap is An outer cylinder extending in the front-rear direction; An inner cylinder disposed inside the outer cylinder and extending in a front-rear direction, When the outer cylinder is fitted to the barrel from the rear side, the inner cylinder is inserted into the rear end opening of the barrel, so that the knock button can be pushed forward. Mechanical pencil.

2. The barrel has a retaining projection that projects radially inward from a rear end opening of the barrel, The inner cylinder has a locking projection which goes over the retaining projection to the front side when the inner cylinder is inserted into the rear end opening of the barrel and is locked to the retaining projection from the front side.

2. The mechanical pencil according to claim 1.

3. The barrel has a retaining projection that projects radially inward from a rear end opening of the barrel, the lead advancing mechanism has a second biasing member that is provided between the lead tank and the knock button and biases the knock button rearward; the knock button has a button locking portion that is locked from a front side by the retaining projection due to the biasing force of the second biasing member; 2. The mechanical pencil according to claim 1.

4. The core tank has a step portion provided on a peripheral wall of the core tank and facing rearward, When the inner cylinder is inserted into the rear end opening of the barrel, the step portion faces or comes into contact with a part of the knock button from the front side with a gap therebetween.

2. The mechanical pencil according to claim 1.

5. The inner cylinder is capable of being reduced in diameter by elastic deformation, When the outer cylinder is fitted to the barrel from the rear side, the inner cylinder is inserted into the rear end opening of the barrel while being reduced in diameter. The mechanical pencil according to any one of claims 1 to 4.

6. The inner cylinder is elastically deformable, When the outer cylinder is fitted to the barrel from the front side, the inner cylinder faces or contacts the outer periphery of the front end of the barrel with a gap therebetween. The mechanical pencil according to any one of claims 1 to 4.

7. The inner cylinder has a plurality of elastic pieces arranged in a circumferential direction around the central axis, Each of the elastic pieces is elastically deformable. The mechanical pencil according to claim 6.

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