Mechanical pencil

Abstract

To prevent a writing lead from being drawn out due to unintended back and forth movement of a weight body in a mechanical pencil having the weight body.SOLUTION: A mechanical pencil 10 includes a barrel 20 including a main shaft 22, a lead feeding mechanism 30 that feeds out a writing lead 80, a weight body 50 arranged so as to be movable back and forth with respect to the main shaft, an operating body 61 rotatable around the central axis A with respect to the main shaft, a moving member 64 that is arranged to be movable back and forth with respect to the operating body and is movable between a restricted position and a non-restricted position located behind the restricted position, a regulating member 68 that regulates the back and forth movement of the weight body when the moving member is located at the restricted position, at least two cam slopes 63a provided on one of the operating body and the moving member, and at least two contact portions 64b provided on the other of the operating body and the moving member. When the operating body rotates around the central axis, the cam slope and the contact portion are in contact with each other, and the contact portion moves along the cam slope.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a sharp pencil.

Background Art

[0002] Conventionally, a sharp pencil having a weight body that can move back and forth with respect to a shaft cylinder is known. In this sharp pencil, when the user shakes the shaft cylinder back and forth, the weight body moves back and forth within the shaft cylinder. At this time, the weight body that has moved forward collides with a part of the core feeding mechanism, causing the core feeding mechanism to operate and the writing core to be fed out. Such a sharp pencil has the advantage that the writing core can be fed out without changing the position of the shaft cylinder. Patent Document 1 discloses such a swing-out type sharp pencil.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional swing-out type sharp pencil, when carried in a bag or the like, the weight body may move back and forth unintentionally due to vibration or the inclination of the sharp pencil, and the writing core may be fed out. In this case, there is a risk that the writing core may be damaged, or the inner surface of the bag or other articles stored inside the bag may be soiled by the fed-out writing core or the damaged writing core.

[0005] The present invention has been made in consideration of such points, and an object thereof is to suppress the feeding out of the writing core due to the unintentional back-and-forth movement of the weight body in a sharp pencil having a weight body.

Means for Solving the Problems

[0006] One embodiment of the present invention is [1] A shaft cylinder including the main shaft, The lead-advancing mechanism that extends the writing lead, A weighted body arranged to be movable back and forth relative to the main shaft, An operating body that can rotate around the central axis relative to the main shaft, A movable member is positioned to be movable back and forth relative to the operating body, and is movable between a restricted position and an unrestricted position behind the restricted position, When the moving member is in the restricted position, a restricting member restricts the forward and backward movement of the heavy body, At least two cam inclined surfaces are provided on one of the operating body and the moving member, The operating body and the other of the moving member have at least two contact portions, The mechanical pencil is such that when the operating body rotates around the central axis, the cam inclined surface and the contact portion move along the cam inclined surface while the contact portion and the cam inclined surface are in contact with each other.

[0007] Other embodiments of the present invention include: [2] The operating body is the mechanical pencil according to [1], which includes a rear shaft that is at least partly located outside the rear portion of the main shaft.

[0008] Further embodiments of the present invention include: [3] The lead advancement mechanism comprises a chuck for gripping the writing lead and a chuck biasing spring for biasing the chuck backward. The mechanical pencil according to [1] or [2], wherein the pressing force exerted by the regulating member when the moving member is in the regulating position is less than the elastic force of the chuck biasing spring.

[0009] Further embodiments of the present invention include: [4] A mechanical pencil according to any one of [1] to [3], wherein a gap is formed between the weight and the regulating member when the movable member is in the regulating position and the weight is in the forward position.

[0010] Still other embodiments of the present invention are as follows. [5] The sharp pencil according to any one of [1] to [4], wherein the restricting member is an elastic member.

[0011] Still other embodiments of the present invention are as follows. [6] The sharp pencil according to [5], wherein the elastic member is a coil spring.

[0012] Still other embodiments of the present invention are as follows. [7] The sharp pencil according to any one of [1] to [6], having a moving member biasing spring for biasing the moving member rearward.

[0013] Still other embodiments of the present invention are as follows. [8] The main shaft has a groove portion provided on the inner peripheral surface and extending in the axial direction. The sharp pencil according to any one of [1] to [7], wherein the moving member has a protruding portion movable within the groove portion. [Advantages of the Invention]

[0014] According to the present invention, in a sharp pencil having a weight body, it is possible to suppress the lead from being fed out due to an unintended forward or backward movement of the weight body. [Brief Description of the Drawings]

[0015] [Figure 1] FIG. 1 is a longitudinal sectional view showing an example of a sharp pencil in an unrestricted state, which shows an embodiment of the present invention. [Figure 2] FIG. 2 is a longitudinal sectional view showing an enlarged view of the movement restricting mechanism of the sharp pencil of FIG. 1. [Figure 3] FIG. 3 is a longitudinal sectional view showing an enlarged view of the movement restricting mechanism in a restricted state. [Figure 4] FIG. 4 is a cross-sectional view corresponding to line IV-IV of FIG. 3. [Figure 5]FIG. 5 is an exploded perspective view showing a part of a mechanical pencil. [Figure 6] FIG. 6 is a perspective view showing the mechanical pencil in a state of being cut along the central axis of the mechanical pencil. [Figure 7] FIG. 7 is a perspective view showing the rotating member of the mechanical pencil in a state of being cut along the central axis. [Figure 8] FIG. 8 is a view showing a part of the movement restricting mechanism in an unrestricted state. [Figure 9] FIG. 9 is a view showing a part of the movement restricting mechanism in a restricted state.

BEST MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to this specification, for the convenience of illustration and easy understanding, the scale, the aspect ratio of the vertical and horizontal dimensions, etc. are appropriately changed and exaggerated from those of the actual object.

[0017] In addition, with regard to terms used in this specification for specifying shapes, geometric conditions, and their degrees, such as terms like "parallel", "orthogonal", "identical", etc., and values of lengths and angles, etc., they are not bound by strict meanings and are to be interpreted to include ranges where similar functions can be expected. <0000@110> In this specification, the direction in which the central axis A of the writing instrument extends (the longitudinal direction, the vertical direction in the longitudinal sectional view) is defined as the axial direction da, the direction orthogonal to the central axis A is defined as the radial direction dr, and the direction along the circumference around the central axis A is defined as the circumferential direction dc. Also, along the axial direction da, the side closer to the writing surface such as paper when writing is taken as the front, and the side separated from the writing surface is taken as the rear. Further, along the radial direction dr, the direction toward the central axis A is taken as the inner side or inward, and the direction away from the central axis A is taken as the outer side or outward.

[0019] Figure 1 is a diagram showing one embodiment of the present invention, and is a longitudinal cross-sectional view showing an example of a mechanical pencil 10 in an unrestricted state. The mechanical pencil 10 of this embodiment comprises a barrel 20, a lead advancement mechanism 30, a weight 50, and a movement restriction mechanism 60. The mechanical pencil 10 also has a central axis A extending in the longitudinal direction.

[0020] The barrel 20 includes a main shaft 22, a rear shaft 24, a tip member 26, and a grip member 28. The central axis of the barrel 20 coincides with the central axis A of the mechanical pencil 10. The front end of the barrel 20 is provided with a front end opening 20a through which the writing lead 80 can pass. In this embodiment, the front end opening 20a is an opening formed at the front end of the tip member 26. The lead advancement mechanism 30 is a mechanism that advances the writing lead 80 forward from the front end opening 20a by operation of the user.

[0021] The main shaft 22 is a component having a substantially cylindrical shape. The rear shaft 24 is a component having a substantially cylindrical shape, positioned behind the main shaft 22. The rear shaft 24 is attached to the main shaft 22 so as to be rotatable around the central axis A but not so as to be able to move back and forth. In particular, in this embodiment, the rear shaft 24 is attached to the main shaft 22 via a rotating member 62, which will be described later. In this embodiment, the rear shaft 24, together with the rotating member 62, constitutes the operating body 61, which will be described later. The tip member 26 is a component that forms the tip portion of the mechanical pencil 10. The tip member 26 has a substantially conical shape, and its outer diameter decreases towards the front. The tip member 26 is connected to the main shaft 22 by attaching the rear end of the tip member 26 to the front end of the main shaft 22. As an example, the tip member 26 is connected to the main shaft 22 by screwing the female thread formed on the inner circumferential surface of the tip member 26 into the male thread formed on the outer circumferential surface of the front end of the main shaft 22. The grip member 28 is made of an elastic material such as rubber or elastomer, and is intended to be held by the user's fingers when writing with the mechanical pencil 10.

[0022] In this specification, "impossible to move forward or backward" is not intended to be limited to those that cannot move forward or backward at all. That is, "impossible to move forward or backward" or "impossible to move in the axial direction da" is a concept that includes those that have play and whose further movement is restricted. Similarly, "impossible to rotate" or "impossible to move in the circumferential direction dc" is a concept that includes those that have play and whose further rotation or movement is restricted.

[0023] The lead feeding mechanism 30 is a mechanism that feeds the writing lead 80 forward from the front end opening 20a of the barrel 20 by the user's operation. The lead feeding mechanism 30 of this embodiment includes a knock body 40, a lead pipe 31, a chuck 32, a connector 33, a chuck biasing spring 35, a receiving member 36, a fastener 37, and a lead holder 38.

[0024] The knock mechanism 40 is a component that is pressed forward by the user when extending the writing lead 80. The knock mechanism 40 is positioned to move back and forth relative to the operating body 61 (rotating member 62). The knock mechanism 40 may or may not be rotatable around the central axis A relative to the operating body 61. In the example shown in Figure 1, the knock mechanism 40 includes a pressing member 42, an erasing member 44, and a cap 46. The pressing member 42 has the function of pressing the lead pipe 31 forward when the knock mechanism 40 is pressed forward. In the illustrated example, the pressing member 42 is a component with a substantially cylindrical shape. The erasing member 44 is a component for erasing the writing by friction. The erasing member 44 is, for example, an eraser. The cap 46 is a component attached to the rear end of the pressing member 42 so as to cover the erasing member 44, and is intended to be pressed by the user's fingers or the like when the user presses the knock body 40 forward.

[0025] A knock-body biasing spring 48 is positioned between the operating body 61 (rotating member 62) and the knock-body 40. The knock-body biasing spring 48 is positioned in a compressed state between the operating body 61 and the knock-body 40. The knock-body biasing spring 48 is, for example, a coil spring. The elastic force of the chuck biasing spring 35, which biases the chuck 32 backward so that the writing lead 80 is properly advanced by the impact load of the weight body 50, may be set to be relatively small. However, in this case, when the knock-body 40 comes into contact with the user or other items, even a small force may cause the chuck 32 to move forward, potentially advancing the writing lead 80 unintentionally. The mechanical pencil 10 of this embodiment has a knock-body biasing spring 48, which allows the pressing force of the knock-body 40 required to advance the writing lead 80 to be increased without increasing the elastic force of the chuck biasing spring 35. Therefore, it is possible to suppress the unintentional advancement of the writing lead 80 when the knock-body 40 comes into contact with the user or other items.

[0026] The pressing member 42 has a projection 42a that protrudes radially outward from the outer circumferential surface of the front portion, an outer flange 42b located behind the projection 42a and formed to protrude radially outward from the outer circumferential surface, and an inner flange 42c formed to protrude radially inward from the inner circumferential surface. The projection 42a engages with the inner flange 62a of the rotating member 62, as described later, to restrict the rearward movement of the knock body 40 relative to the rotating member 62. The outer flange 42b is the part that receives the elastic force of the knock body biasing spring 48. When the knock body 40 is pressed forward, the inner flange 42c contacts the rear end of the core pipe 31 and presses the core pipe 31 forward.

[0027] The core pipe 31 is a component that stores the writing lead 80 inside. In this embodiment, the core pipe 31 also has the function of transmitting the pressing force from the knock body 40 to the connector 33 when the user presses the knock body 40 forward. Such a core pipe 31 is made of resin, for example. When the knock body 40 is not pressed forward (see Figures 1 to 3), the pressing member 42 is biased backward by the elastic force of the knock body biasing spring 48. Therefore, when the knock body 40 is not pressed forward, a gap is formed between the rear end of the core pipe 31 and the inner flange portion 42c of the pressing member 42 along the axial direction da. When such a gap is formed between the rear end of the lead pipe 31 and the inner flange portion 42c of the pressing member 42, the lead pipe 31 will not move forward even if the knock mechanism 40 comes into contact with the inner surface of the bag or other items stored inside the bag when the mechanical pencil 10 is carried in the bag, causing the knock mechanism 40 to be slightly pressed forward. Therefore, it is possible to prevent the writing lead 80 from being unintentionally extended from the mechanical pencil 10.

[0028] The chuck 32 is a component that grips the writing lead 80. The chuck 32 can move back and forth integrally with the lead pipe 31 and the connector 33. The connector 33 is a component that connects the lead pipe 31 and the chuck 32. In the illustrated example, the rear end of the connector 33 is inserted into the front end of the lead pipe 31, thereby fixing the connector 33 to the lead pipe 31. Similarly, the rear end of the chuck 32 is inserted into the front end of the connector 33, thereby fixing the chuck 32 to the connector 33.

[0029] A chuck biasing spring 35 is positioned in front of the connector 33. The chuck biasing spring 35 is, for example, a coil spring. A receiving member 36 is positioned in front of the chuck biasing spring 35, and the chuck biasing spring 35 is positioned in a compressed state between the front end of the connector 33 and the receiving member 36. The receiving member 36 is a member that receives the elastic force of the chuck biasing spring 35. The receiving member 36 is pressed forward by the elastic force of the chuck biasing spring 35 and contacts a stepped portion formed on the inner surface of the tip member 26. The clamping tool 37 is an annular component located radially outward from the front portion of the chuck 32. The rear end of the clamping tool 37 contacts the receiving member 36, thereby restricting the rearward movement of the clamping tool 37. The lead holder 38 is positioned in front of the chuck 32 and is a member that contacts the outer surface of the writing lead 80 to hold the writing lead 80. The lead holder 38 is made of an elastic material such as rubber, and prevents the writing lead 80 from moving axially da when the chuck 32 is not gripping the writing lead 80.

[0030] The weight body 50 is a cylindrical member extending in the axial direction da. The weight body 50 is positioned outside the core pipe 31 so as to surround the core pipe 31. The weight body 50 is made of a relatively dense material, such as a metal material. A gap is formed between the weight body 50 and the core pipe 31, and the weight body 50 can easily move in the axial direction da relative to the core pipe 31. In particular, when the user shakes the mechanical pencil 10 along the axial direction da, the weight body 50 moves in the axial direction da relative to the core pipe 31.

[0031] The connector 33 has a contact portion 33a that protrudes more than the outer surface of the core pipe 31 outward in the radial direction dr. When the weight 50 moves forward and collides with the contact portion 33a of the connector 33 from behind, the impact load acting on the connector 33 from the weight 50 causes the connector 33 to move forward.

[0032] When the lead 80 is advanced by the lead advancement mechanism 30, the knock body 40 is pressed forward by the user. As the knock body 40 moves forward, the axial dimension da in the gap formed between the rear end of the lead pipe 31 and the inner flange portion 42c of the pressing member 42 of the knock body 40 decreases. When the inner flange portion 42c of the pressing member 42 contacts the rear end of the lead pipe 31, and the knock body 40 is further pressed forward, the knock body 40, lead pipe 31, connector 33, and chuck 32 move forward against the elastic force of the knock body biasing spring 48 and the chuck biasing spring 35. Also, when the user swings the mechanical pencil 10 along the axial direction da, the weight 50 moves forward and collides with the contact portion 33a of the connector 33, causing the lead pipe 31, connector 33, and chuck 32 to move forward against the elastic force of the chuck biasing spring 35.

[0033] The outer surface of the front portion of the chuck 32 is in contact with the fastener 37 from the inside when the knock body 40 is not pressed forward. Therefore, the front portion of the chuck 32 is prevented from opening outward in the radial direction dr. As a result, the front portion of the chuck 32 grips the writing lead 80. When the chuck 32 moves forward, the writing lead 80 gripped by the chuck 32 moves forward, and the writing lead 80 is fed forward from the front end opening 20a of the barrel 20. When the chuck 32 moves further forward, the front portion of the chuck 32 moves forward relative to the fastener 37. As a result, the front portion of the chuck 32 opens outward in the radial direction dr, and the writing lead 80 that was gripped by the front portion of the chuck 32 is released. At this time, the writing lead 80 is held by the lead holder 38.

[0034] When the user releases the pressure on the knock mechanism 40, the elastic force of the knock mechanism biasing spring 48 and the chuck biasing spring 35 causes the knock mechanism 40, lead pipe 31, connector 33, and chuck 32 to move backward. Similarly, when the pressure on the connector 33 by the weight 50 is released, the elastic force of the chuck biasing spring 35 causes the lead pipe 31, connector 33, and chuck 32 to move backward. As the chuck 32 moves backward, its front portion moves inside the clamp 37 and contacts the clamp 37 to grip the writing lead 80. At this time, since the writing lead 80 is held by the lead holder 38, its backward movement is suppressed. In this writing instrument of this embodiment, the writing lead 80 is thus fed forward from the front end opening 20a of the barrel 20.

[0035] Incidentally, with conventional retractable mechanical pencils, when carried in a bag or similar item, vibrations or tilting of the pencil could unintentionally cause the weight to shift back and forth, resulting in the lead being extended. In this case, there was a risk that the lead would break, or that the extended lead or broken lead would stain the inside of the bag or other items stored inside the bag.

[0036] To prevent such problems from occurring, the mechanical pencil 10 of this embodiment has a movement restricting mechanism 60 that can restrict the movement of the weight body 50 in the axial direction da. The movement restricting mechanism 60 makes it possible to switch the mechanical pencil 10 between an unrestricted state in which the movement of the weight body 50 is not restricted and a restricted state in which the movement of the weight body 50 is restricted. Figure 2 is a longitudinal cross-sectional view showing the movement restricting mechanism 60 in the unrestricted state, and Figure 3 is a longitudinal cross-sectional view showing the movement restricting mechanism 60 in the restricted state.

[0037] In the unrestricted state shown in Figure 2, the range of movement of the weight 50 in the axial direction da is larger than that of the weight 50 in the restricted state. Therefore, when the mechanical pencil 10 is swung along the axial direction da, the weight 50 moves significantly in the front-to-back direction. As a result, when the weight 50 collides with the contact portion 33a of the connector 33, a larger impact load is applied from the weight 50 to the connector 33 than the impact load applied from the weight 50 to the connector 33 in the restricted state. Consequently, the lead pipe 31, connector 33, and chuck 32 move forward against the elastic force of the chuck biasing spring 35, and the writing lead 80 is fed out from the front end opening 20a of the barrel 20.

[0038] On the other hand, in the restricted state shown in Figure 3, the range of movement of the weight 50 in the axial direction da is narrowed. Therefore, the range of movement of the weight 50 in the front-to-back direction when the mechanical pencil 10 is swung along the axial direction da is narrowed. As a result, the impact load that the weight 50 exerts on the connector 33 when it collides with the contact portion 33a of the connector 33 is also smaller than the impact load that the weight 50 exerts on the connector 33 in the unrestricted state. In this case, the forward movement of the lead pipe 31, the connector 33, and the chuck 32 against the elastic force of the chuck biasing spring 35 is suppressed, and the writing lead 80 is also suppressed from being fed out from the front end opening 20a of the barrel 20. In this specification, the restriction of the front-to-back movement of the weight 50 means that the range of movement of the weight 50 in the axial direction da is narrowed.

[0039] The details of the movement restriction mechanism 60 will be described below with reference to Figures 2 to 9. Figure 4 is a cross-sectional view corresponding to line IV-IV in Figure 3, and Figure 5 is an exploded perspective view showing a part of the mechanical pencil 10 including the movement restriction mechanism 60. Figure 6 is a perspective view showing the main shaft 22 cut along the central axis A, and Figure 7 is a perspective view showing the rotating member 62 of the movement restriction mechanism 60 cut along the central axis A. Figure 8 shows a part of the movement restriction mechanism 60 in an unrestricted state, and Figure 9 shows a part of the movement restriction mechanism 60 in a restricted state.

[0040] The movement restricting mechanism 60 of this embodiment includes a groove 22a and an inner step 22b provided on the main shaft 22, an operating body 61, a moving member 64, a moving member biasing spring 66, and a restricting member 68.

[0041] The spindle 22 of this embodiment has a groove 22a and an inner step 22b. The groove 22a is provided on the inner circumferential surface of the spindle 22 and extends in the axial direction da. In particular, the groove 22a extends in a straight line. The spindle 22 may have a plurality of grooves 22a. The plurality of grooves 22a may be arranged at equal angular intervals from each other. In the illustrated example, the spindle 22 has two grooves 22a that are 180 degrees apart from each other. However, the spindle 22 may have one groove 22a or three or more grooves 22a. The inner step 22b is a step provided on the inner circumferential surface of the spindle 22 and includes a rearward-facing surface. The inner step 22b is the part that receives the elastic force of the moving member biasing spring 66.

[0042] The operating body 61 is a component operated by the user to switch the mechanical pencil 10 between an unrestricted state and a restricted state. The operating body 61 is mounted to the main shaft 22 so as to be rotatable about the central axis A and immovable forward or backward. In this embodiment, the operating body 61 includes a rear shaft 24 and a rotating member 62. At least a portion of the rear shaft 24 is located outside the rear portion of the main shaft 22. In the illustrated example, a portion of the front side of the rear shaft 24, including the front end, is located outside the rear portion of the main shaft 22. The rear shaft 24 is located radially outward dr from the rotating member 62. Furthermore, the rear shaft 24 is fixed to the rotating member 62 so as to be immovable and immovable forward or backward around the central axis A. In particular, the rear portion of the rear shaft 24 is fixed to the rear portion of the rotating member 62.

[0043] The rotating member 62 is a member having a substantially cylindrical shape. The rotating member 62 is mounted on the main shaft 22 so as to be rotatable about the central axis A but unable to move back and forth. The rotating member 62 has an inner flange portion 62a and a cam portion 63. The inner flange portion 62a is formed to protrude inward in the radial direction dr from the inner circumferential surface. In the example shown in Figures 2 and 3, the protrusion 42a of the pressing member 42 can be locked onto the front surface of the inner flange portion 62a, and when the protrusion 42a of the pressing member 42 is locked onto the front surface of the inner flange portion 62a, the rearward movement of the knock body 40 relative to the rotating member 62 is restricted. The rear surface of the inner flange portion 62a is the part that receives the elastic force of the knock body biasing spring 48. In the illustrated example, the knock body biasing spring 48 is positioned between the inner flange 62a of the rotating member 62 and the outer flange 42b of the pressing member 42 of the knock body 40.

[0044] The cam portion 63 works in cooperation with the contact portion 64b of the moving member 64 to switch the mechanical pencil 10 between a restricted state and an unrestricted state. Figures 8 and 9 show the shape of the cam portion 63 of the rotating member 62. Figures 8 and 9 are unfolded views of the main shaft 22, the rotating member 62, and the moving member 64, cut open by planes extending in the axial direction da and the radial direction dr. In Figures 8 and 9, the groove portion 22a of the main shaft 22, the cam portion 63 of the rotating member 62, and the protruding portion 64a and contact portion 64b of the moving member 64, which will be described later, are shown as viewed from the outside in the radial direction dr.

[0045] The rotating member 62 has at least two cam portions 63. The at least two cam portions 63 may be arranged at equal angular intervals from each other. In the illustrated example, the rotating member 62 has two cam portions 63 that are 180 degrees apart from each other. However, the rotating member 62 may have three or more cam portions 63.

[0046] The cam portion 63 includes a cam inclined surface 63a, a locking recess 63b, and a protrusion 63c. The cam inclined surface 63a is the surface that the contact portion 64b moves in contact with when the rotating member 62 rotates around the central axis A. The cam inclined surface 63a extends spirally in a direction inclined with respect to both the axial direction da and the circumferential direction dc (see Figure 7). In the unfolded views of Figures 8 and 9, the cam inclined surface 63a is shown to extend linearly in a direction inclined with respect to both the axial direction da and the circumferential direction dc. However, it is not limited to this, and the cam inclined surface 63a may extend curved in an unfolded view cut open with planes extending in the axial direction da and the radial direction dr as shown in Figures 8 and 9. The locking recess 63b is the portion where the contact portion 64b is located in the restricted state. The locking recess 63b is recessed toward the rear. The protrusion 63c is a so-called return stopper that prevents the contact portion 64b, located at the locking recess 63b, from moving toward the cam slope 63a. The protrusion 63c is located between the cam slope 63a and the locking recess 63b. The protrusion 63c protrudes forward from the locking recess 63b.

[0047] The inclination angle θ1 of the cam bevel 63a with respect to the circumferential direction dc may be 30 degrees or more and 80 degrees or less (see Figure 9). Preferably, the inclination angle θ1 may be 40 degrees or more and 75 degrees or less, 50 degrees or more and 70 degrees or less, or 60 degrees or more and 65 degrees or less.

[0048] The movable member 64 is a substantially cylindrical member and is located inside the main shaft 22. The movable member 64 is positioned relative to the main shaft 22 so as to be immobile around the central axis A and movable in the axial direction da. The movable member 64 is movable back and forth relative to the operating body 61 (rotating member 62). The operating body 61 (rotating member 62) is rotatable around the central axis A relative to the movable member 64. The movable member 64 is also movable between a restricted position (see Figures 3 and 9) and an unrestricted position behind the restricted position (see Figures 2 and 8). In this embodiment, when the movable member 64 is in the restricted position, the mechanical pencil 10 is in a restricted state, and when the movable member 64 is in the unrestricted position, the mechanical pencil 10 is in an unrestricted state.

[0049] A projection 64a is formed on the outer circumferential surface of the movable member 64, projecting outward in the radial direction dr. In the illustrated example, the projection 64a is provided on the outer circumferential surface of the front portion of the movable member 64. In particular, the movable member 64 has a large-diameter portion located in the front portion and a small-diameter portion located behind the large-diameter portion and having a smaller outer diameter than the outer diameter of the large-diameter portion, and the projection 64a is provided on the outer circumferential surface of the large-diameter portion. The projection 64a extends linearly along the axial direction da. The projection 64a is located within the groove 22a of the main shaft 22 and is configured to be movable within the groove 22a in the axial direction da. Therefore, the projection 64a is provided corresponding to each groove 22a of the main shaft 22. The movable member 64 has the same number of projections 64a as the grooves 22a of the main shaft 22. In the illustrated example, the movable member 64 has two projections 64a that are 180 degrees apart from each other. Furthermore, the rear portion of the movable member 64 is located inside the front portion of the rotating member 62.

[0050] A contact portion 64b is formed on the outer circumferential surface of the movable member 64, intended to abut against the cam portion 63 of the rotating member 62. In the illustrated example, the contact portion 64b is formed to protrude radially outward from the outer circumferential surface of the movable member 64 in the radial direction dr. In the illustrated example, the contact portion 64b is provided on the outer circumferential surface of the rear portion of the movable member 64. In particular, the contact portion 64b is provided on the outer circumferential surface of the small diameter portion of the movable member 64. The contact portion 64b extends linearly along the axial direction da. The rear end of the contact portion 64b that directly abuts against the cam portion 63 has a curved shape. In particular, in the examples shown in Figures 8 and 9, the rear end of the contact portion 64b has a semicircular shape when viewed from the radial direction dr. Because the portion of the contact portion 64b that directly abuts against the cam portion 63 has a curved shape, the contact portion 64b can move smoothly along the cam slope 63a while abutting against it.

[0051] The movable member 64 has at least two contact portions 64b. The at least two contact portions 64b may be arranged at equal angular intervals from each other. In the illustrated example, the movable member 64 has two contact portions 64b that are spaced 180 degrees apart θ2 from each other (see Figure 9). However, the movable member 64 may have three or more contact portions 64b. In this embodiment, the movable member 64 has the same number of contact portions 64b as the number of cam portions 63 (cam inclined surfaces 63a) of the rotating member 62. That is, the mechanical pencil 10 has two cam portions 63 and two contact portions 64b. However, the mechanical pencil 10 may have three cam portions 63 and three contact portions 64b, or four cam portions 63 and four contact portions 64b.

[0052] If a mechanical pencil has only one cam inclination and one contact point, when the operating body rotates, the pressing force is transmitted from the operating body to the moving member at only one point. In this case, the moving member may tilt with respect to the central axis. If the moving member tilts, it may catch on the barrel and may not move back and forth properly. In this embodiment, one of the operating body 61 (rotating member 62) and the moving member 64 has at least two cam inclinations 63a, and the other of the operating body 61 (rotating member 62) and the moving member 64 has at least two contact points 64b, so that the pressing force is transmitted from the operating body 61 to the moving member 64 at at least two points. This suppresses tilting of the moving member 64 with respect to the central axis A when pressed by the operating body 61. Therefore, the moving member 64 can move back and forth stably relative to the operating body 61. In other words, the mechanical pencil 10 can stably switch between a restricted state and an unrestricted state.

[0053] In this embodiment, the protruding portion 64a and the contact portion 64b are arranged side by side in the axial direction da (see Figures 5, 8, and 9). In other words, the protruding portion 64a and the contact portion 64b are arranged at the same angle in the circumferential direction dc when viewed from the axial direction da. In particular, in the illustrated example, the protruding portion 64a and the contact portion 64b are arranged overlapping in the radial direction dr when viewed from the axial direction da. An inner flange portion 64c is formed on the inner circumferential surface of the movable member 64, protruding inward in the radial direction dr. The inner flange portion 64c is the part intended to come into contact with the regulating member 68.

[0054] The moving member biasing spring 66 is a member that biases the moving member 64 backward. The moving member biasing spring 66 is, for example, a coil spring. The moving member biasing spring 66 is positioned in a compressed state between the moving member 64 and the main shaft 22. In particular, the moving member biasing spring 66 is positioned between the front end 64d of the moving member 64 and the inner stepped portion 22b of the main shaft 22. As a result, the moving member 64 is always biased backward relative to the shaft cylinder 20 (main shaft 22).

[0055] The restricting member 68 is a member that restricts the forward and backward movement of the weight body 50 when the moving member 64 is in the restricted position, that is, when the mechanical pencil 10 is in a restricted state. More specifically, the restricting member 68 narrows the range of movement of the weight body 50 in the axial direction da when in the restricted state. The restricting member 68 is a member having a substantially cylindrical shape and is positioned between the rear end of the weight body 50 and the moving member 64. In particular, the restricting member 68 is positioned between the rear end of the weight body 50 and the inner flange portion 64c of the moving member 64. When in the restricted state, the moving member 64 is positioned in the restricted position, which is forward of the unrestricted position. Consequently, the restricting member 68 also moves forward. This narrows the range of movement of the weight body 50 in the axial direction da.

[0056] When the movable member 64 is in the restricted position, the restricting member 68 may contact the rear end of the weight body 50. In this case, even if the mechanical pencil 10 is shaken along the axial direction da while in the restricted state, the weight body 50 will not move along the axial direction da. As a result, the weight body 50 does not apply a collision load to the contact portion 33a of the connector 33, thus suppressing the extension of the writing lead 80. Furthermore, since the weight body 50 does not move along the axial direction da, it is possible to suppress the generation of collision noise by preventing the weight body 50 from colliding with the connector 33 or the restricting member 68.

[0057] Furthermore, when the movable member 64 is in the restricted position and the weight body 50 is in its furthest forward position, a gap may be formed between the weight body 50 and the restricting member 68. In this case as well, in the restricted state, the range of movement of the weight body 50 in the axial direction da is narrowed, so the impact load generated when the weight body 50 collides with the contact portion 33a of the connector 33 when the mechanical pencil 10 is swung along the axial direction da is reduced. This suppresses the writing lead 80 from being extended from the front end opening 20a of the barrel 20.

[0058] The regulating member 68 may be an elastic member. In this case, even if the weight 50 moves back and forth and collides with the regulating member 68 in the regulated state, the generation of collision noise between the weight 50 and the regulating member 68 can be suppressed. The elastic member may be, for example, a coil spring.

[0059] In the restricted state, the restricting member 68 may be positioned in a compressed state between the rear end of the weight body 50 and the movable member 64. In this case, it is preferable that the pressing force exerted by the restricting member 68 on the weight body 50 when the movable member 64 is in the restricted position is smaller than the elastic force of the chuck biasing spring 35. This allows the elastic force of the restricting member 68 to suppress the forward movement of the weight body 50, connector 33, and chuck 32 against the elastic force of the chuck biasing spring 35. Therefore, it is possible to suppress the reduction in the force with which the chuck 32 grips the writing lead 80, as the front portion of the chuck 32 opens outward in the radial direction dr by moving forward relative to the fastener 37.

[0060] The regulating member 68 may be fixed to the movable member 64, or it may not be fixed to the movable member 64 but be arranged to move back and forth between the movable member 64 and the weight 50. Alternatively, the regulating member 68 may be formed integrally with the movable member 64.

[0061] Next, the operation of the movement control mechanism 60 will be explained, mainly with reference to Figures 2, 3, 8, and 9.

[0062] As shown in Figures 2 and 8, in the unrestricted state, the elastic force of the moving member biasing spring 66 causes the moving member 64 to be positioned in the unrestricted position, which is further back than the restricted position. In this state, the range of movement of the weight body 50 in the axial direction da is larger than the range of movement of the weight body 50 in the axial direction da in the restricted state. Therefore, when the mechanical pencil 10 is swung along the axial direction da, the weight body 50 moves significantly in the front-rear direction. As a result, when the weight body 50 collides with the contact portion 33a of the connector 33, a larger impact load is applied from the weight body 50 to the connector 33 than the impact load applied from the weight body 50 to the connector 33 in the restricted state. Therefore, the lead pipe 31, connector 33, and chuck 32 move forward against the elastic force of the chuck biasing spring 35, and the writing lead 80 is advanced from the front end opening 20a of the barrel 20. In other words, the writing lead 80 can be advanced by the weight body 50.

[0063] To switch the mechanical pencil 10 from an unrestricted state to a restricted state, in the unrestricted state, the user rotates the rear shaft 24, which constitutes the operating body 61, around the central axis A relative to the main shaft 22. This causes the rotating member 62 to rotate around the central axis A together with the rear shaft 24. In this embodiment, when the user rotates the rear shaft 24 clockwise when viewed from the rear of the main shaft 22, the moving member 64 moves from the unrestricted position to the restricted position, and the mechanical pencil 10 switches from an unrestricted state to a restricted state. As the rotating member 62 rotates, the cam portion 63 of the rotating member 62 moves along the circumferential direction dc. In Figures 8 and 9, the cam portion 63 moves upward along the circumferential direction dc (see the white arrow in Figure 9).

[0064] The movable member 64 is positioned relative to the main shaft 22 so as to be immobile around the central axis A and movable in the axial direction da. As the cam portion 63 moves in the circumferential direction dc, the contact portion 64b of the movable member 64 moves forward along the cam slope 63a while contacting the cam slope 63a of the cam portion 63. At this time, the movable member biasing spring 66, which is positioned between the movable member 64 and the main shaft 22, is compressed by the movable member 64. When the contact portion 64b exceeds the convex portion 63c of the cam portion 63, the elastic force of the compressed movable member biasing spring 66 presses the contact portion 64b against the locking recess 63b of the cam portion 63, and the contact portion 64b locks into the locking recess 63b. As a result, the movable member 64 is positioned in the restricted position, and the mechanical pencil 10 is in a restricted state.

[0065] In the restricted state, the restricting member 68 narrows the range of axial movement da of the weight body 50. That is, the forward and backward movement of the weight body 50 is restricted. As a result, the impact load acting from the weight body 50 to the connector 33 when the weight body 50 collides with the contact portion 33a of the connector 33 is reduced. Consequently, the chuck 32 is prevented from moving forward against the elastic force of the chuck biasing spring 35. As a result, the writing lead 80 is prevented from being fed out from the front end opening 20a of the barrel 20.

[0066] To switch from a restricted state to an unrestricted state, the user rotates the operating body 61 in the opposite direction around the central axis A while in the unrestricted state. In this embodiment, the user rotates the rear shaft 24 counterclockwise when viewed from the rear of the main shaft 22. As the operating body 61 (rotating member 62) rotates, the cam portion 63 of the rotating member 62 moves along the circumferential direction dc. In Figures 8 and 9, the cam portion 63 moves downward along the circumferential direction dc. When the contact portion 64b of the moving member 64 overcomes the convex portion 63c of the cam portion 63, the biasing force of the moving member biasing spring 66 pushes the moving member 64 backward. As a result, the contact portion 64b pushes the cam inclined surface 63a backward, and the cam inclined surface 63a rotates around the central axis A while in contact with the contact portion 64b. As a result, the moving member 64 is positioned in the unrestricted position, and the mechanical pencil 10 enters the unrestricted state.

[0067] When the mechanical pencil 10 has two cam portions 63 and two contact portions 64b, the angular interval θ3 between the angle of the contact portions 64b in the circumferential direction dc when the movable member 64 is in the unrestricted position and the angle of the contact portions 64b in the circumferential direction dc when the movable member 64 is in the restricted position may be, for example, 90 degrees or more and 170 degrees or less (see Figure 9). Preferably, the angular interval θ3 may be 100 degrees or more and 160 degrees or less, 110 degrees or more and 150 degrees or less, or 120 degrees or more and 140 degrees or less.

[0068] The mechanical pencil 10 of this embodiment includes a barrel 20 including a main shaft 22, a lead feeding mechanism 30 for feeding a writing lead 80, a weight body 50 positioned to move back and forth relative to the main shaft 22, an operating body 61 rotatable about a central axis A relative to the main shaft 22, a movable member 64 positioned to move back and forth relative to the operating body 61 and movable between a restricted position and an unrestricted position behind the restricted position, a restricting member 68 that restricts the back and forth movement of the weight body 50 when the movable member 64 is in the restricted position, at least two cam inclined surfaces 63a provided on one of the operating body 61 and the movable member 64, and at least two contact portions 64b provided on the other of the operating body 61 and the movable member 64, wherein when the operating body 61 rotates about a central axis A, the cam inclined surfaces 63a and the contact portions 64b come into contact with each other, and the contact portions 64b move along the cam inclined surfaces 63a.

[0069] With this type of mechanical pencil 10, when the moving member 64 is in the restricted position, the restricting member 68 restricts the forward and backward movement of the weight body 50. As a result, the impact load that acts from the weight body 50 to the connector 33 when the weight body 50 collides with the contact portion 33a of the connector 33 is reduced. Therefore, the chuck 32 is prevented from moving forward against the elastic force of the chuck biasing spring 35. As a result, the writing lead 80 is prevented from being fed out from the front end opening 20a of the barrel 20.

[0070] Furthermore, in this type of mechanical pencil 10, one of the operating body 61 (rotating member 62) and the moving member 64 has at least two cam inclined surfaces 63a, and the other of the operating body 61 (rotating member 62) and the moving member 64 has at least two contact portions 64b, so that pressing force is transmitted from the operating body 61 to the moving member 64 at at least two locations. This prevents the moving member 64 from tilting with respect to the central axis A when pressed by the operating body 61. Therefore, the moving member 64 can move stably back and forth relative to the operating body 61. In other words, the mechanical pencil 10 can stably switch between a restricted state and an unrestricted state.

[0071] In the mechanical pencil 10 of this embodiment, the operating body 61 includes a rear shaft 24, at least a portion of which is located outside the rear portion of the main shaft 22.

[0072] With this type of mechanical pencil 10, the user can operate the control unit 61 without having to change their grip on the mechanical pencil 10 when switching between the unrestricted and restricted states. Therefore, the user can easily switch between the unrestricted and restricted states.

[0073] In the mechanical pencil 10 of this embodiment, the lead advancement mechanism 30 includes a chuck 32 that grips the writing lead 80 and a chuck biasing spring 35 that biases the chuck 32 backward. When the moving member 64 is in the restricted position, the pressing force exerted by the restricting member 68 on the weight body 50 is smaller than the elastic force of the chuck biasing spring 35.

[0074] With this type of mechanical pencil 10, the elastic force of the regulating member 68 prevents the weight body 50, connector 33, and chuck 32 from moving forward against the elastic force of the chuck biasing spring 35. Therefore, it is possible to prevent the chuck 32 from moving forward relative to the clamp 37, which would cause the front portion of the chuck 32 to open outward in the radial direction dr, thus reducing the gripping force of the chuck 32 on the writing lead 80.

[0075] In the mechanical pencil 10 of this embodiment, a gap is formed between the weight body 50 and the regulating member 68 when the movable member 64 is in the regulating position and the weight body 50 is in the furthest forward position.

[0076] Even with this type of mechanical pencil 10, the range of movement of the weight 50 in the axial direction da is narrowed in the restricted state, so the impact load generated when the weight 50 collides with the contact portion 33a of the connector 33 when the mechanical pencil 10 is swung along the axial direction da is reduced. As a result, the writing lead 80 is prevented from being extended from the front end opening 20a of the barrel 20.

[0077] In the mechanical pencil 10 of this embodiment, the regulating member 68 is an elastic member.

[0078] In the mechanical pencil 10 of this embodiment, the elastic member is a coil spring.

[0079] With this type of mechanical pencil 10, even if the weight 50 moves back and forth and collides with the regulating member 68 in the restricted state, it is possible to suppress the generation of collision noise between the weight 50 and the regulating member 68.

[0080] The mechanical pencil 10 of this embodiment has a moving member biasing spring 66 that biases the moving member 64 to the rear.

[0081] In this type of mechanical pencil 10, the moving member 64 is always biased backward relative to the barrel 20 (main shaft 22). This allows the contact portion 64b of the moving member 64 to always be pressed against the cam portion 63. Therefore, the contact portion 64b makes proper contact with the cam inclination surface 63a of the cam portion 63, enabling stable forward and backward movement of the moving member 64. In the mechanical pencil 10 of this embodiment, the main shaft 22 has a groove 22a provided on its inner circumferential surface that extends in the axial direction, and the movable member 64 has a protruding portion 64a that can move within the groove 22a.

[0082] With this type of mechanical pencil 10, the groove 22a guides the movable member 64, allowing the movable member 64 to move back and forth appropriately.

[0083] In the above-described embodiment, an example was described in which the operating body 61 of the mechanical pencil 10 has a cam slope 63a and the moving member 64 has a contact portion 64b. However, the invention is not limited to this, and the operating body 61 may have a contact portion and the moving member 64 may have a cam slope. Even in this case, the mechanical pencil 10 can exhibit the same effects as in the above-described embodiment.

[0084] Furthermore, in the above-described embodiment, the rear shaft 24 constitutes part of the operating body 61, but the configuration of the operating body 61 is not limited to this. For example, an annular member rotatable about a central axis A may be placed between the main shaft and the rear shaft 24, and the operating body 61 may be composed of this annular member and a rotating member 62. In this case, the annular member may be fixed to the rotating member 62 so as not to rotate about the central axis A and not to move back and forth. Even in this case, the user can operate the operating body 61 without changing their grip on the mechanical pencil 10 when switching between the unrestricted state and the restricted state. Therefore, the unrestricted state and the restricted state can be easily switched. [Explanation of symbols]

[0085] 10 Mechanical Pencils 20 shaft cylinder 20a Front end opening 22 Main axis 22a Groove 22b Inner section 24 rear axle 26. Tip component 28 Grip component 30 Lead advance mechanism 31 Core pipe 32 Chuck 33 Connectors 33a Contact part 35 Chuck biasing spring 36 Receiving member 37 Fasteners 38 Core holder 40 knock type 42 Pressing member 42a Protrusion 42b Outer flange 42c Inner flange 44 Erasing Member 46 caps 48 Knock body biasing spring 50 weight body 60 Movement control organizations 61 Operating Body 62 Rotating Member 62a Inner flange 63 Cam section 63a Cam slope 63b Locking recess 63c protrusion 64 Moving Member 64a Protrusion 64b Contact part 64c Inner flange 64d front end 66. Moving member biasing spring 68 Regulating members 80 writing lead da axis direction dr radial direction dc circumferential direction

Claims

1. The shaft cylinder including the main shaft, The lead-advancing mechanism that extends the writing lead, A weighted body arranged to be movable back and forth relative to the main shaft, An operating body that can rotate around the central axis relative to the main shaft, A movable member is positioned to be movable back and forth relative to the operating body, and is movable between a restricted position and an unrestricted position behind the restricted position, When the moving member is in the restricted position, a restricting member restricts the forward and backward movement of the heavy body, At least two cam inclined surfaces are provided on one of the operating body and the moving member, The operating body and the other of the moving member have at least two contact portions, The aforementioned regulating member is an elastic member, A mechanical pencil in which, when the operating body rotates around the central axis, the cam inclined surface and the contact portion move along the cam inclined surface while the contact portion and the cam inclined surface are in contact with each other.

2. The mechanical pencil according to claim 1, wherein the operating body includes a rear shaft, at least a portion of which is located outside the rear portion of the main shaft.

3. The lead advancement mechanism includes a chuck for gripping the writing lead and a chuck biasing spring for biasing the chuck backward. The mechanical pencil according to claim 1 or 2, wherein the pressing force exerted by the regulating member when the moving member is in the regulating position is less than the elastic force of the chuck biasing spring.

4. The mechanical pencil according to claim 1 or 2, wherein a gap is formed between the weight and the regulating member when the moving member is in the regulating position and the weight is in its furthest forward position.

5. The mechanical pencil according to claim 1 or 2, wherein the elastic member is a coil spring.

6. The mechanical pencil according to claim 1 or 2, further comprising a moving member biasing spring that biases the moving member backward.

7. The main shaft has a groove on its inner circumferential surface that extends in the axial direction, The mechanical pencil according to claim 1 or 2, wherein the movable member has a protruding portion that can move within the groove.

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