JP7844243B2 - mechanical pencil - Google Patents

Description

This invention relates to a mechanical pencil.

Conventionally, mechanical pencils are known that have a weight inside the barrel that can move back and forth relative to the barrel. In this type of mechanical pencil, the user shakes the barrel back and forth, causing the weight to move back and forth within the barrel. When the weight moves forward, it collides with a part of the lead-advancing mechanism, activating the mechanism and advancing the lead. Such mechanical pencils have the advantage of allowing the lead to be advanced without changing the grip on the barrel. Patent Document 1 discloses such a retractable mechanical pencil.

Japanese Patent Application Publication No. 9-1980

With conventional retractable mechanical pencils, when carried in a bag, 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 of the lead breaking, or the extended or broken lead soiling the inside of the bag or other items stored inside.

This invention was made with these points in mind, and aims to prevent the lead from being advanced due to unintended back-and-forth movement of the weight in a mechanical pencil having a weight.

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.

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 a part of which is located outside the rear portion of the main shaft.

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.

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.

Further embodiments of the present invention include:
[5] The regulating member is an elastic member, a mechanical pencil as described in any one of [1] to [4].

Further embodiments of the present invention include:
[6] The elastic member is a coil spring, or the mechanical pencil described in [5].

Further embodiments of the present invention include:
[7] A mechanical pencil according to any one of [1] to [6], having a moving member biasing spring that biases the moving member to the rear.

Further embodiments of the present invention include:
[8] The main shaft has a groove on its inner circumferential surface that extends in the axial direction,
The movable member is a mechanical pencil according to any one of [1] to [7], having a protruding portion that can move within the groove.

According to the present invention, in a mechanical pencil having a weighted body, it is possible to suppress the unintended forward and backward movement of the weighted body from causing the writing lead to advance.

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 in an unregulated state. Figure 2 is a cross-sectional view showing an enlarged view of the movement restriction mechanism of the mechanical pencil in Figure 1. Figure 3 is a magnified longitudinal cross-sectional view showing the movement control mechanism in a restricted state. Figure 4 is a cross-sectional view corresponding to the line IV-IV in Figure 3. Figure 5 is an exploded perspective view showing a part of a mechanical pencil. Figure 6 is a perspective view showing the main shaft of a mechanical pencil cut along its central axis. Figure 7 is a perspective view showing the rotating component of a mechanical pencil cut along its central axis. Figure 8 shows a portion of the movement control mechanism in an unregulated state. Figure 9 shows a portion of the movement control mechanism in a restricted state.

An embodiment of the present invention will be described below with reference to the drawings. Note that, for the sake of illustration and ease of understanding, the scale and aspect ratios of the drawings accompanying this specification have been appropriately altered and exaggerated from those of the actual objects.

Furthermore, terms such as "parallel," "orthogonal," and "identical," as well as values for length and angle, used in this specification to specify shapes, geometric conditions, and their degrees, shall not be strictly interpreted, but rather shall be interpreted to include a range that allows for the expectation of similar functionality.

In this specification, the direction in which the central axis A of the writing instrument extends (longitudinal direction, vertical direction in a longitudinal section view) is defined as the axial direction da, the direction perpendicular 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. Furthermore, along the axial direction da, the side closer to the writing surface (such as paper) during writing is defined as the front, and the side further away from the writing surface is defined as the rear. Also, along the radial direction dr, the direction toward the central axis A is defined as the inward or internal direction, and the direction away from the central axis A is defined as the outward or external direction.

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-feeding mechanism 30, a weight 50, and a movement-restricting mechanism 60. The mechanical pencil 10 also has a central axis A extending in the longitudinal direction.

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 through the front end opening 20a by the user's operation.

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 threaded portion formed on the inner circumferential surface of the tip member 26 into the male threaded portion 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.

Furthermore, in this specification, "impossible to move forward or backward" is not intended to be limited to cases where movement is completely impossible. That is, "impossible to move forward or backward" or "impossible to move in the axial direction da" includes cases where further movement is restricted by play. Similarly, "impossible to rotate" or "impossible to move in the circumferential direction dc" includes cases where further rotation or movement is restricted by play.

The lead advancement mechanism 30 is a mechanism that advances the writing lead 80 forward from the front end opening 20a of the barrel 20 by the user's operation. The lead advancement mechanism 30 in 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.

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 having 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 other body parts when the user presses the knocking body 40 forward.

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 causing the writing lead 80 to be advanced 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.

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 (described later), restricting 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. The inner flange 42c contacts the rear end of the core pipe 31 when the knock body 40 is pressed forward, thereby pressing the core pipe 31 forward.

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, for example, resin. 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, 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 a bag, causing the knock mechanism 40 to be slightly pressed forward, the lead pipe 31 will not move forward. Therefore, it is possible to prevent the writing lead 80 from being unintentionally extended from the mechanical pencil 10.

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.

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 in the axial direction da when the chuck 32 is not gripping the writing lead 80.

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, surrounding it. The weight body 50 is made of a relatively dense material, such as metal. A gap is formed between the weight body 50 and the core pipe 31, allowing the weight body 50 to 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.

The connector 33 has a contact portion 33a that protrudes larger than the outer circumferential surface of the core pipe 31 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.

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. Furthermore, 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.

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 radially outward in the direction dr. This causes the front portion of the chuck 32 to grip 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. This causes the front portion of the chuck 32 to open radially outward in the direction dr, releasing the writing lead 80 that was gripped by the front portion of the chuck 32. At this time, the writing lead 80 is held by the lead holder 38.

When the user releases 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 inward into the clamp 37, contacting the clamp 37 and gripping 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.

Incidentally, with conventional retractable mechanical pencils, when carried in a bag or similar container, 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 of the lead breaking, or the extended or broken lead soiling the inside of the bag or other items stored inside.

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

In the unrestricted state shown in Figure 2, the range of motion 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.

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 acting from the weight 50 on the connector 33 when the weight 50 collides with the contact portion 33a of the connector 33 is smaller than the impact load acting from the weight 50 on the connector 33 in the unrestricted state. In this case, the forward movement of the lead pipe 31, connector 33, and 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, "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.

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.

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.

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 linearly. The spindle 22 may have multiple grooves 22a. Multiple grooves 22a may be arranged at equal angular intervals from each other. In the illustrated example, the spindle 22 has two grooves 22a spaced 180 degrees apart. However, it is not limited to this; 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.

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 around 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 positioned 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 its front end, is positioned outside the rear portion of the main shaft 22. The rear shaft 24 is positioned radially outward from the rotating member 62 in the direction dr. 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.

The rotating member 62 is a member having a substantially cylindrical shape. The rotating member 62 is mounted to the main shaft 22 so as to be rotatable around 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 protruding portion 42a of the pressing member 42 can be locked to the front surface of the inner flange portion 62a, and when the protruding portion 42a of the pressing member 42 is locked to 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.

The cam portion 63, in cooperation with the contact portion 64b of the movable member 64, has the function of switching 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 movable 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 movable member 64 (described later) are shown as viewed from the outside in the radial direction dr.

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 spaced 180 degrees apart from each other. However, it is not limited to this; the rotating member 62 may have three or more cam portions 63.

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 while 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 a plane 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 extends forward beyond the locking recess 63b.

The inclination angle _θ1 of the cam inclined surface 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.

The movable member 64 is a substantially cylindrical member and is positioned within 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. Furthermore, the movable member 64 is 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.

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.

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 area 64b that directly contacts the cam portion 63 has a curved shape, the contact area 64b can move smoothly along the cam inclination 63a while contacting it.

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 from each other _θ2 (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.

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. When the moving member tilts, it may catch on the barrel, preventing it from moving 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. As a result, 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.

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 contact the regulating member 68.

The moving member biasing spring 66 is a component 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).

The restricting member 68 is a member that restricts the forward and backward movement of the weight body 50 when the movable member 64 is in the restricted position, that is, when the mechanical pencil 10 is in the 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 with a substantially cylindrical shape and is positioned between the rear end of the weight body 50 and the movable 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 movable member 64. When in the restricted state, the movable 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.

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. This prevents the weight body 50 from applying 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, collision noise caused by the weight body 50 colliding with the connector 33 or the restricting member 68 can be suppressed.

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. Even in this case, since the range of movement of the weight body 50 in the axial direction da is narrowed in the restricted state, 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.

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

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 gripping force of the chuck 32 on the writing lead 80 due to the forward movement of the chuck 32 relative to the clamp 37, which would cause the front portion of the chuck 32 to open outward in the radial direction dr.

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

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

As shown in Figures 2 and 8, in the unrestricted state, the elastic force of the moving member biasing spring 66 positions the moving member 64 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.

To switch the mechanical pencil 10 from the unrestricted state to the restricted 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 along with the rear shaft 24. In this embodiment, the user rotates the rear shaft 24 clockwise when viewed from the rear of the main shaft 22, causing the moving member 64 to move from the unrestricted position to the restricted position, and the mechanical pencil 10 switches from the unrestricted state to the 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).

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 it. At this time, the movable member biasing spring 66, 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, causing the contact portion 64b to lock into the locking recess 63b. This positions the movable member 64 in the restricted position, and the mechanical pencil 10 enters a restricted state.

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. This reduces the impact load acting from the weight body 50 on the connector 33 when the weight body 50 collides with the contact portion 33a of the connector 33. Therefore, the chuck 32 is prevented from moving forward against the elastic force of the chuck biasing spring 35. This prevents the writing lead 80 from being fed out from the front end opening 20a of the barrel 20.

To switch from the restricted state to the 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 relative to 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 presses 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. This places the moving member 64 in the unrestricted position, and the mechanical pencil 10 enters the unrestricted state.

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.

The mechanical pencil 10 of this embodiment includes a barrel 20 containing a main shaft 22, a lead advance mechanism 30 for advancing the writing lead 80, a weight body 50 positioned to move back and forth relative to the main shaft 22, an operating body 61 rotatable around 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. When the operating body 61 rotates around the 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.

In 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. This reduces the impact load acting from the weight body 50 on the connector 33 when the weight body 50 collides with the contact portion 33a of the connector 33. Therefore, the chuck 32 is prevented from moving forward against the elastic force of the chuck biasing spring 35. This prevents the writing lead 80 from being fed out from the front end opening 20a of the barrel 20.

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. Therefore, pressing force is transmitted from the operating body 61 to the moving member 64 at at least two points. This prevents the moving member 64 from tilting relative to the central axis A when pressed by the operating body 61. Consequently, 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.

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.

With this type of mechanical pencil 10, the user can operate the control unit 61 without changing their grip on the mechanical pencil 10 when switching between the unrestricted and restricted states. Therefore, switching between the unrestricted and restricted states can be done easily.

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 50 is less than the elastic force of the chuck biasing spring 35.

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.

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

Even with this type of mechanical pencil 10, the range of movement of the weight 50 in the axial direction da is narrowed under restricted conditions. Therefore, when the mechanical pencil 10 is swung along the axial direction da, the impact load generated when the weight 50 collides with the contact portion 33a of the connector 33 is reduced. This suppresses the writing lead 80 from being extended from the front end opening 20a of the barrel 20.

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

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

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, the generation of collision noise between the weight 50 and the regulating member 68 can be suppressed.

The mechanical pencil 10 of this embodiment has a moving member biasing spring 66 that biases the moving member 64 backward.

In this type of mechanical pencil 10, the movable member 64 is always biased backward relative to the barrel 20 (main shaft 22). This allows the contact portion 64b of the movable member 64 to always be pressed against the cam portion 63. Therefore, the contact portion 64b makes proper contact with the cam slope 63a of the cam portion 63, enabling stable forward and backward movement of the movable member 64.
In the mechanical pencil 10 of this embodiment, the main shaft 22 has a groove 22a 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.

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.

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

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 around the 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 around 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.

10 Mechanical pencil 20 Shaft cylinder 20a Front end opening 22 Main shaft 22a Groove 22b Inner step 24 Rear shaft 26 Tip member 28 Grip member 30 Lead feeding mechanism 31 Lead pipe 32 Chuck 33 Connector 33a Contact part 35 Chuck biasing spring 36 Receiving member 37 Fastener 38 Lead holder 40 Knock body 42 Pressing member 42a Protruding part 42b Outer flange 42c Inner flange 44 Eraser member 46 Cap 48 Knock body biasing spring 50 Weight 60 Movement restricting mechanism 61 Operating body 62 Rotating member 62a Inner flange 63 Cam part 63a Cam slope 63b Locking recess 63c Protrusion 64 Moving member 64a Protruding part 64b Contact part 64c Inner flange 64d Front end 66 Moving member biasing spring 68 Restricting member 80 Writing lead da Axial direction dr Radial direction dc Circumferential direction

Claims (7)

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. 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. 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. 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. The mechanical pencil according to claim 1 or 2 , wherein the elastic member is a coil spring. A mechanical pencil according to claim 1 or 2, comprising a moving member biasing spring that biases the moving member backward. 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.