JP2025007336A - Mechanical pencil - Google Patents

Abstract

[Problem] The pin for pushing out the writing lead is prevented from bending or breaking. [Solution] A mechanical pencil (10) has a push-out pin (55) that pushes out the writing lead (100) forward, and has a retraction mechanism (60) that includes an elastic member (62) and retracts the push-out pin (55) by the elastic force of the elastic member (62). [Selected Figure] Figure 6

Description

The present invention relates to a mechanical pencil.

Conventionally, mechanical pencils are known that use a pin to push the lead from the rear to the front, allowing the lead to be advanced forward (Patent Document 1).

Japanese Utility Model Publication No. 59-7109

When refilling or replacing the lead in such a mechanical pencil, it is conceivable to configure the barrel so that it can be separated at the middle, and insert the lead into the front part separated at the middle. In this case, the pin for pushing out the lead may remain protruding from the rear part separated at the middle. In this case, there is a risk that the pin protruding from the rear part may come into contact with other parts and bend or break.

The present invention was made with these points in mind, and aims to prevent the pin used to push out the writing lead from bending or breaking.

The mechanical pencil of the present invention is
[1] A mechanical pencil equipped with an ejection pin that pushes the writing core forward,
The mechanical pencil has a retraction mechanism that includes an elastic member and retracts the ejector pin by the elastic force of the elastic member.

The mechanical pencil of the present invention is
[2] The mechanical pencil according to [1], wherein the elastic member is a spiral spring.

The mechanical pencil of the present invention is
[3] The mechanical pencil according to [1] or [2], further comprising a regulating mechanism for regulating the retraction of the ejection pin.

The mechanical pencil of the present invention is
[4] The regulating mechanism is
A contact member capable of contacting the spiral spring;
The mechanical pencil according to [3] has a biasing member capable of biasing the contact member toward the spiral spring.

The mechanical pencil of the present invention is
[5] The mechanical pencil described in [3] or [4], further comprising a switching mechanism capable of switching between a regulated state in which the regulating mechanism regulates the retraction of the ejector pin and a non-regulated state in which the regulating mechanism does not regulate the retraction of the ejector pin.

The mechanical pencil of the present invention is
[6] The switching mechanism has a moving member,
The biasing member is disposed between the contact member and the moving member,
The mechanical pencil according to any one of [3] to [5], wherein in the regulated state, the movable member moves closer to the spiral spring, thereby pressing the contact member against the spiral spring.

The mechanical pencil of the present invention is
[7] The switching mechanism has an operation unit,
When the operating portion is rotated in one circumferential direction, the moving member moves toward the spiral spring,
The mechanical pencil described in [6], wherein when the operating part is rotated to the other side in the circumferential direction, the moving member moves so as to move away from the spiral spring.

The mechanical pencil of the present invention is
[8] The mechanical pencil according to any one of [4] to [6], wherein the biasing member is a coil spring.

The present invention makes it possible to prevent the pin for pushing out the writing lead from bending or breaking.

FIG. 1 is a diagram showing an embodiment of the present invention, and is an external view showing an example of a mechanical pencil. FIG. 2 is a vertical cross-sectional view of the mechanical pencil of FIG. FIG. 3 is a perspective view showing a chuck mechanism of the mechanical pencil. FIG. 4 is a cross-sectional view showing a holding mechanism of the mechanical pencil. FIG. 5 is a perspective view showing an elastic body of the holding mechanism. FIG. 6 is a vertical cross-sectional view showing the push-out mechanism, the retraction mechanism, the restriction mechanism, and the switching mechanism of the mechanical pencil. FIG. 7 is a diagram showing an operation portion of the switching mechanism. FIG. 8 is a diagram for explaining pushing out of the writing lead using the pushing mechanism. FIG. 9 is a diagram for explaining a method for refilling or replacing the writing lead. FIG. 10 is a vertical cross-sectional view showing the rear portion with the ejector pin protruding forward. FIG. 11 is a perspective view showing a modified example of the holding mechanism. FIG. 12 is a cross-sectional view showing the holding mechanism of FIG. FIG. 13 is a perspective view showing another modified example of the holding mechanism. FIG. 14 is a cross-sectional view showing the retention mechanism of FIG. FIG. 15 is a perspective view showing still another modified example of the holding mechanism. FIG. 16 is a cross-sectional view taken along line XVI-XVI in FIG. FIG. 17 is a cross-sectional view taken along line XVII-XVII of FIG. FIG. 18 is a perspective view showing still another modified example of the holding mechanism. FIG. 19 is a cross-sectional view showing the retention mechanism of FIG.

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

In addition, terms used in this specification that specify shapes, geometric conditions, and the extent of those conditions, such as "parallel," "orthogonal," and "same," as well as values of lengths and angles, are not to be construed as being limited to their strict meanings, but rather should be interpreted to include the range within which similar functions can be expected.

In this specification, the direction in which the central axis A of the mechanical pencil 10 extends (longitudinal direction, up and down direction in a longitudinal cross section) is referred to as the axial direction da, the direction perpendicular to the axial direction da is referred to as the radial direction, and the direction along the circumference around the central axis A is referred to as the circumferential direction dc. In addition, along the axial direction da, the side approaching a writing surface such as a paper surface when writing is referred to as the front, and the side moving away from the writing surface is referred to as the rear. In addition, along the radial direction, the side approaching the central axis A is referred to as the inside or inner side, and the side moving away from the central axis A is referred to as the outside or outer side.

The mechanical pencil 10 of this embodiment is configured so that the writing lead 100 can be advanced forward by sliding the push-out operation part 57, which will be described later, forward. In addition, the mechanical pencil 10 of this embodiment can select and use a plurality of writing leads 100 having different diameters. An example of the specific configuration of the mechanical pencil 10 of this embodiment is described below.

Figure 1 shows an embodiment of the present invention, and is an external view of an example of a mechanical pencil 10. Figure 2 shows a vertical cross-sectional view of the mechanical pencil 10.

The mechanical pencil 10 of this embodiment includes a barrel 20, a chuck mechanism 30, a holding mechanism 40, a push-out mechanism 50, a retraction mechanism 60, a restriction mechanism 70, and a switching mechanism 80.

The barrel 20 extends in the axial direction da along the central axis A of the mechanical pencil 10. Therefore, the central axis of the barrel 20 coincides with the central axis A of the mechanical pencil 10. The barrel 20 includes a front shaft 22 and a rear shaft 24 connected to the rear end of the front shaft 22.

The front shaft 22 is a member that forms the front portion of the mechanical pencil 10. The tip portion of the front shaft 22 has a generally conical shape, and its outer diameter decreases toward the front. The front shaft 22 may be composed of one member or multiple members. In this embodiment, the front shaft 22 is intended to be held by the user's fingers when writing with the mechanical pencil 10. The front shaft 22 may include an inner shaft and a grip portion disposed on the outside of the inner shaft. The grip portion is the portion that is held by the user's fingers when writing with the mechanical pencil 10.

The rear shaft 24 is a member that forms the rear portion of the mechanical pencil 10. The rear shaft 24 is a member having a generally cylindrical shape. The rear shaft 24 may be composed of one member or multiple members. The front end of the rear shaft 24 is attached to the rear end of the front shaft 22, thereby connecting the rear shaft 24 to the front shaft 22. As an example, the rear shaft 24 is connected to the front shaft 22 by screwing a female threaded portion formed on the inner periphery of the front end of the rear shaft 24 into a male threaded portion formed on the outer periphery of the rear end of the front shaft 22.

The rear axle 24 has a slit 26, an opening 28, and an engagement protrusion 29. The slit 26 is a through hole that penetrates the wall of the rear axle 24 in the radial direction and extends linearly along the axial direction da. A part of the push-out operation part 57, which will be described later, is disposed within the slit 26. In this state, the push-out operation part 57 can move in the front-rear direction along the slit 26. The opening 28 is an opening provided for attaching a rivet 64 to the main body part 53 of the slide member 51, which will be described later. The engagement protrusion 29 engages with a groove part 87 of an operation part 85, which will be described later.

3 is a perspective view showing the chuck mechanism 30. The chuck mechanism 30 is a mechanism for holding the writing core 100. In particular, the chuck mechanism 30 holds the writing core 100 so that a predetermined length of the writing core 100 protrudes from the tip of the mechanical pencil 10. The chuck mechanism 30 suppresses the tip of the writing core 100 from shifting radially during writing. This suppresses the writing core 100 from breaking or the writing from becoming distorted during writing. The chuck mechanism 30 of this embodiment is configured to be able to hold writing cores 100 having different diameters without replacing the parts that make up the mechanical pencil 10. In other words, the chuck mechanism 30 of this embodiment is capable of holding a writing core 100 having a relatively small diameter without replacing the parts that make up the mechanical pencil 10, and is also capable of holding a writing core 100 having a diameter larger than the writing core 100. The diameter of the writing core 100 may be, for example, 0.3 mm or more and 1.0 mm or less. More specifically, the diameter of the writing core 100 may be, for example, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1.0 mm.

The chuck mechanism 30 includes a base 32, a claw member 34, and an elastic member 38. The base 32 is a portion that holds the claw member 34. A through hole through which the writing core 100 can pass is formed in the center portion of the base 32. This through hole extends along the central axis A. The chuck mechanism 30 has a plurality of claw members 34. In this embodiment, the chuck mechanism 30 has three claw members 34. The chuck mechanism 30 may have two claw members 34, or may have four or more claw members 34. Each claw member 34 is connected to the front end of the base 32. In the example shown in FIG. 3, the base 32 and the claw member 34 are integrally formed with each other. The claw member 34 is configured to be elastically deformable in the radial direction. The claw member 34 may be made of, for example, resin, metal, or the like. In particular, from the viewpoint of reducing the weight and cost of the mechanical pencil 10, it is preferable that the claw member 34 is made of resin.

The multiple claw members 34 are arranged side by side with equal angular pitches in the circumferential direction dc. In the example shown in FIG. 3, three claw members 34 are arranged side by side with an angular pitch of 120 degrees in the circumferential direction dc. Each of the claw members 34 extends forward from the front end of the base 32. The claw members 34 extend in a direction inclined with respect to both the axial direction da and the radial direction so as to move radially inward as they move forward. A recess 36 extending in the circumferential direction dc is formed on the outer peripheral surface of the claw member 34. In particular, the recess 36 is formed on the outer peripheral surface of the front end of the claw member 34.

The elastic member 38 has the function of pressing the multiple claw members 34 radially inward. In this embodiment, the elastic member 38 is an O-ring extending in the circumferential direction dc. At least a portion of the elastic member 38 is disposed in the recess 36 of the claw member 34. The elastic member 38 is formed of an elastic material such as rubber or elastomer. When the elastic member 38 presses the multiple claw members 34 radially inward, the front ends of the claw members 34 are close to each other when the writing core 100 is not positioned between the multiple claw members 34. In particular, when the writing core 100 is not positioned between the multiple claw members 34, the front ends of the claw members 34 are close to each other with a gap that does not allow the thinnest writing core 100 that the chuck mechanism 30 can grip to pass through unless the elastic member 38 is elastically deformed. For example, if the diameter of the thinnest writing lead 100 that the chuck mechanism 30 can grip is 0.3 mm, when the writing lead 100 is not positioned between the multiple claw members 34, the front ends of the claw members 34 are close to each other with a gap that prevents the writing lead 100 with a diameter of 0.3 mm from passing through unless the elastic member 38 is elastically deformed. When the writing lead 100 is not positioned between the multiple claw members 34, for example, the front ends of the claw members 34 may be in contact with each other.

In such a chuck mechanism 30, the writing core 100 that has advanced through the through hole of the base 32 is inserted between the multiple claw members 34 from the rear. At this time, the multiple claw members 34 are pushed outward in the radial direction. This allows the writing core 100 to advance further. When the writing core 100 is positioned between the multiple claw members 34, the elastic member 38 presses the multiple claw members 34 toward the writing core 100. This prevents the writing core 100 from retracting even if writing pressure is applied to the writing core 100 from the front during writing. In the mechanical pencil 10 of this embodiment, the claw members 34 are configured to be elastically deformable in the radial direction, and the elastic member 38 is configured to press the claw members 34 toward the writing core 100. Therefore, even if writing cores 100 with different diameters are inserted between the multiple claw members 34, the writing core 100 can be properly held.

Figure 4 is a cross-sectional view showing the retention mechanism 40. In particular, Figure 4 is a cross-sectional view corresponding to line IV-IV in Figure 2. Figure 5 is a perspective view showing the elastic body 42 of the retention mechanism 40.

The holding mechanism 40 extends along the central axis A and has the function of holding the rear portion of the writing lead 100 held by the chuck mechanism 30. The holding mechanism 40 holds the writing lead 100 behind the chuck mechanism 30. In the example shown in FIG. 4, the holding mechanism 40 includes an elastic body 42 and a shape-maintaining member 46.

The elastic body 42 is formed of an elastic material such as rubber or elastomer. As a result, the elastic body 42 elastically holds the writing core 100. The elastic body 42 has a plurality of protruding portions 44 that protrude toward the central axis A and are arranged in the circumferential direction dc. When the writing core 100 is positioned within the holding mechanism 40, the protruding portions 44 protrude toward the writing core 100. The protruding portions 44 are portions that contact the writing core 100 and hold the writing core 100. The protruding portions 44 extend linearly along the axial direction da. Therefore, the protruding portions 44 contact the writing core 100 over a predetermined length along the axial direction da.

The multiple protrusions 44 are arranged side by side with equal angular pitches from each other in the circumferential direction dc. In the example shown in Figs. 4 and 5, three protrusions 44 are arranged side by side with an angular pitch of 120 degrees from each other in the circumferential direction dc. The holding mechanism 40 may have two protrusions 44, or may have four or more protrusions 44. In the example shown, the elastic body 42 is made of a single member. Therefore, in the example shown, multiple protrusions 44 are formed on the elastic body 42, which is made of a single member formed of an elastic material.

The shape retention member 46 has the function of maintaining the shape of the elastic body 42. The shape retention member 46 is disposed radially outward from the elastic body 42. The shape retention member 46 has an approximately cylindrical shape overall. The inner peripheral surface of the shape retention member 46 has a shape corresponding to the outer peripheral surface of the elastic body 42. In particular, the inner peripheral surface of the shape retention member 46 has a shape complementary to the outer peripheral surface of the elastic body 42. As a result, the shape of the outer peripheral surface of the elastic body 42 is maintained by the shape retention member 46.

A stopper 48 is disposed behind the holding mechanism 40. The stopper 48 is provided to prevent the chuck mechanism 30 and the holding mechanism 40 from slipping out rearward relative to the front shaft 22. The stopper 48 is inserted into the front shaft 22 via the rear end of the front shaft 22. The stopper 48 is fixed to the front shaft 22. For example, the stopper 48 is fixed to the front shaft 22 by means of press-fitting, screwing, or the like. A through hole is formed in the center of the stopper 48, through which the writing lead 100 can pass. This through hole extends along the central axis A. This through hole also functions as a guide portion for appropriately guiding the writing lead 100 toward the center of the holding mechanism 40 when refilling the mechanical pencil 10 with the writing lead 100.

Figure 6 is an enlarged vertical cross-sectional view showing the push-out mechanism 50, the retraction mechanism 60, the restriction mechanism 70, and the switching mechanism 80.

The extrusion mechanism 50 has the function of pushing the writing lead 100 held by the chuck mechanism 30 forward. In particular, the extrusion mechanism 50 pushes the writing lead 100 forward, causing the front end of the writing lead 100 to protrude a predetermined length from the front end of the mechanical pencil 10. The extrusion mechanism 50 includes a slide member 51 and an extrusion operation unit 57.

The slide member 51 is disposed within the shaft tube 20 and is configured to be movable back and forth along the axial direction da. The slide member 51 includes a main body portion 53 and an ejection pin 55. The ejection pin 55 extends linearly forward from the main body portion 53. The rear end of the ejection pin 55 is connected to the main body portion 53. The main body portion 53 and the ejection pin 55 may be formed integrally with each other. Alternatively, the main body portion 53 and the ejection pin 55 may be formed separately from each other and connected to each other.

The push-out operation unit 57 is connected to the slide member 51. In particular, the push-out operation unit 57 is connected to the main body 53 of the slide member 51 through the slit 26 of the rear shaft 24. The push-out operation unit 57 is fixed to the slide member 51. Therefore, the slide member 51 and the push-out operation unit 57 move back and forth together along the axial direction da. The push-out operation unit 57 is movable over the entire length of the slit 26. Therefore, the slide member 51 and the push-out operation unit 57 move back and forth by a distance corresponding to the length of the slit 26.

The push-out operation unit 57 of this embodiment has a head 58 and a male screw portion extending inward from the head 58. The male screw portion of the push-out operation unit 57 is screwed into the female screw portion formed in the main body 53, thereby connecting the push-out operation unit 57 to the main body 53. The wall portion of the rear shaft 24 is located between the head 58 of the push-out operation unit 57 and the main body 53 of the slide member 51. When the male screw portion of the push-out operation unit 57 is tightened against the female screw portion of the main body 53 with the wall portion of the rear shaft 24 sandwiched between the head 58 and the main body 53, the slide member 51 and the push-out operation unit 57 are fixed to the rear shaft 24. In other words, the slide member 51 and the push-out operation unit 57 do not move in the front-rear direction relative to the rear shaft 24. In this state, when the male thread of the push-out operation part 57 is loosened from the female thread of the main body part 53, a gap is created between the head part 58 and the wall of the rear axle 24, and between the main body part 53 and the wall of the rear axle 24. This allows the slide member 51 and the push-out operation part 57 to move in the front-rear direction relative to the rear axle 24.

A washer 59 is attached to the portion of the extrusion operation part 57 that is inward from the male threaded portion. This prevents the male threaded portion from slipping outward from the female threaded portion of the main body 53, even if the male threaded portion of the extrusion operation part 57 is loosened from the female threaded portion of the main body 53. In other words, the washer 59 functions as a retainer for the extrusion operation part 57.

In this embodiment, when refilling or replacing the writing lead 100, the rear shaft 24 is removed from the front shaft 22, and the writing lead 100 is inserted into the through hole of the stopper 48, as shown in FIG. 9. At this time, if the slide member 51 is positioned forward, the ejection pin 55 remains protruding from the front end of the rear shaft 24, as shown in FIG. 10. In this case, there is a risk that the ejection pin 55 protruding from the rear shaft 24 may come into contact with other members and bend or break. To solve this problem, the mechanical pencil 10 of this embodiment is equipped with a retraction mechanism 60 that retracts the ejection pin 55.

The retraction mechanism 60 includes an elastic member 62. The elastic member 62 is preferably a spring member. In this embodiment, the elastic member 62 is a spiral spring. Accordingly, in this specification, the elastic member 62 is also called a spiral spring 62. Note that the elastic member 62 is not limited to a spiral spring, and may be other spring members such as a coil spring. One end of the spiral spring 62 is attached to the main body 53 of the slide member 51 by a rivet 64. In a state where no external force is acting, the spiral spring 62 is in a wound state as shown in FIG. 6. When the user operates the push-out operation unit 57 to move the slide member 51 forward, the spiral spring 62 is unwound. When the user releases the forward pressing force on the push-out operation unit 57, the slide member 51 is pulled back rearward by the elastic force of the spiral spring 62.

At this time, even though the slide member 51 is biased rearward by the spiral spring 62, it may be desired that the slide member 51 not be pulled back rearward. The mechanical pencil 10 of this embodiment is provided with a restriction mechanism 70 that restricts the retraction of the ejector pin 55. The restriction mechanism 70 includes a frame member 72, a contact member 74, and a biasing member 78.

The frame member 72 is a member that holds the spiral spring 62, the contact member 74, and the biasing member 78. That is, the spiral spring 62, the contact member 74, and the biasing member 78 are attached to the frame member 72. The contact member 74 has a contact surface 76 and is configured to be able to contact the spiral spring 62 at the contact surface 76. The contact member 74 is disposed behind the spiral spring 62, and the front end surface of the contact member 74 constitutes the contact surface 76. The biasing member 78 is configured to be able to bias the contact member 74 toward the spiral spring 62. The biasing member 78 is, for example, a coil spring. The biasing member 78 is disposed behind the contact member 74 and can bias the contact member 74 forward. In this embodiment, the restriction mechanism 70 has two contact members 74 and two biasing members 78. The two contact members 74 are arranged side by side in a direction perpendicular to the central axis A. The two biasing members 78 are arranged side by side in a direction perpendicular to the central axis A. Furthermore, one biasing member 78 is provided corresponding to one contact member 74.

The biasing force of the biasing member 78 presses the contact member 74 against the spiral spring 62. In this state, the frictional force generated between the contact surface 76 and the outer surface of the spiral spring 62 suppresses the winding of the spiral spring 62. At this time, while the slide member 51 is biased rearward by the spiral spring 62, the slide member 51 is suppressed from being pulled back rearward.

The mechanical pencil 10 of this embodiment is equipped with a switching mechanism 80 that can switch between a restricted state in which the retraction of the ejector pin 55 is restricted by the restricting mechanism 70 and a non-restricted state in which the retraction of the ejector pin 55 is not restricted by the restricting mechanism 70. The switching mechanism 80 includes a moving member 82 and an operating unit 85.

The moving member 82 is provided so as to be movable in the axial direction da. The moving member 82 is disposed rearward of the urging member 78. In other words, the urging member 78 is disposed between the contact member 74 and the moving member 82. The moving member 82 has a protrusion 84. The protrusion 84 extends forward from a main body of the moving member 82. The protrusion 84 is located inside the urging member 78. This allows the urging member 78 and the moving member 82 to be aligned.
The moving member 82 has two protrusions 84. One protrusion 84 is provided for one biasing member 78.

The biasing member 78 is disposed in a compressed state between the contact member 74 and the moving member 82. When the moving member 82 moves (forward) toward the spiral spring 62, the biasing member 78 is further compressed between the contact member 74 and the moving member 82. At this time, a larger biasing force is generated in the biasing member 78. This larger biasing force presses the contact member 74 against the spiral spring 62, suppressing the winding of the spiral spring 62. In other words, the retraction of the ejector pin 55 is restricted (restricted state).

On the other hand, when the moving member 82 moves away from the spiral spring 62 (rearward), the biasing member 78 expands, and the biasing force generated in the biasing member 78 decreases. This reduces the force pressing the contact member 74 against the spiral spring 62, allowing the spiral spring 62 to be wound up. In other words, the retraction of the ejector pin 55 is no longer restricted (unrestricted state).

The operating unit 85 is a part that the user operates when activating the switching mechanism 80. The operating unit 85 includes a side wall portion 86 and a pressing portion 88. The side wall portion 86 has a cylindrical shape and is located radially outward from the rear shaft 24. The central axis of the side wall portion 86 coincides with the central axis A of the mechanical pencil 10. The pressing portion 88 is a part that presses the moving member 82 forward when the operating unit 85 moves forward. The pressing portion 88 is fixed to the rear end of the side wall portion 86. In the example shown in FIG. 6, the pressing portion 88 is a lid portion that at least partially closes the rear end of the side wall portion 86. The side wall portion 86 and the pressing portion 88 may be formed integrally with each other. Also, the side wall portion 86 and the pressing portion 88 may be formed separately from each other and connected to each other.

The operating unit 85 is attached to the rear end of the rear axle 24 so as to be rotatable in the circumferential direction dc. The operating unit 85 is configured to move forward when rotated to one side in the circumferential direction dc, and to move rearward when rotated to the other side in the circumferential direction dc. The moving member 82 is pressed against the pressing portion 88 by the biasing force of the biasing member 78. That is, the moving member 82 is always in contact with the pressing portion 88. When the operating unit 85 moves forward, the moving member 82 is pressed by the pressing portion 88 and moves forward. Therefore, when the operating unit 85 is rotated to one side in the circumferential direction dc, the moving member 82 moves closer to the spiral spring 62. Also, when the operating unit 85 is rotated to the other side in the circumferential direction dc, the moving member 82 moves away from the spiral spring 62. The other side in the circumferential direction dc is the opposite side to the one side in the circumferential direction dc.

A groove 87 is formed in the side wall 86. The engagement protrusion 29 of the rear axle 24 engages with the groove 87. The groove 87 and the engagement protrusion 29 allow the operating part 85 to move forward and backward. This mechanism is explained below. Figure 7 is a diagram showing the side wall 86 and groove 87 of the operating part 85. Figure 7 shows the side wall 86 cut open by a straight line parallel to the axial direction da.

6 and 7, the groove portion 87 is a through hole that penetrates the side wall portion 86 in the radial direction. However, the groove portion 87 is not limited to this, and may be a groove that is formed on the inner circumferential surface of the side wall portion 86 and does not penetrate the side wall portion 86 in the radial direction. The groove portion 87 includes a first portion 92, a second portion 94, and a connection portion 96. The first portion 92 and the second portion 94 each extend in the circumferential direction dc. The second portion 94 is located rearward and on the other side of the circumferential direction dc with respect to the first portion 92. In particular, the first portion 92 and the second portion 94 are arranged with a pitch P along the axial direction da. The connection portion 96 is a portion that connects the first portion 92 and the second portion 94. In particular, the connection portion 96 connects the other end of the first portion 92 in the circumferential direction dc to the one end of the second portion 94 in the circumferential direction dc. The connection portion 96 extends in a direction inclined with respect to both the axial direction da and the circumferential direction dc so as to move toward the other side of the circumferential direction dc as it moves toward the rear. The engagement projection 29 of the rear axle 24 is movable within the groove portion 87 across the first portion 92, the connection portion 96, and the second portion 94.

7, the side wall portion 86 and the groove portion 87 when the operating unit 85 is located forward are shown by solid lines, and the side wall portion 86 and the groove portion 87 when the operating unit 85 is located rearward are shown by dashed lines. The rear axle 24 is formed with two engagement protrusions 29. The two engagement protrusions 29 are arranged side by side in the circumferential direction dc with an angular pitch of 180 degrees from each other. The operating unit 85 has the same number of groove portions 87 as the number of engagement protrusions 29. Therefore, in this embodiment, the operating unit 85 has two groove portions 87. The two groove portions 87 are arranged side by side in the circumferential direction dc with an angular pitch of 180 degrees from each other. Note that this is not limited to this, and the rear axle 24 may have one engagement protrusion 29 or three or more engagement protrusions 29. Accordingly, the operating unit 85 may have one groove portion 87 or three or more groove portions 87.

When the operating part 85 is located at the rear, the engagement protrusion 29 is located in the first part 92 of the groove part 87. When the user rotates the operating part 85 toward one side in the circumferential direction dc, the engagement protrusion 29 moves from the first part 92 through the connection part 96 to the second part 94. At this time, the operating part 85 moves forward. In particular, the operating part 85 moves forward by a distance equal to the pitch P along the axial direction da between the first part 92 and the second part 94. As a result, the moving member 82 is pressed by the pressing part 88 and moves forward.

In the mechanical pencil 10 of this embodiment, when the writing core 100 is advanced, the user moves the extrusion operation part 57 forward along the slit 26 of the rear shaft 24. As a result, the extrusion pin 55 of the slide member 51 moves forward and presses the writing core 100 from the rear. As a result, the writing core 100 is advanced forward (see FIG. 8). At this time, the multiple claw members 34 of the chuck mechanism 30 are pushed outward in the radial direction. When the writing core 100 is positioned between the multiple claw members 34, the elastic member 38 presses the multiple claw members 34 toward the writing core 100. This prevents the tip of the writing core 100 from shifting in the radial direction during writing. In the mechanical pencil 10 of this embodiment, the claw members 34 are configured to be elastically deformable in the radial direction, and the elastic member 38 is configured to press the claw members 34 toward the writing core 100. Therefore, even if writing leads 100 with different diameters are inserted between multiple claw members 34, the writing leads 100 can be properly held.

In addition, when the wall of the rear shaft 24 is sandwiched between the head 58 of the push-out operation part 57 and the main body part 53 of the slide member 51, the male screw part of the push-out operation part 57 is tightened against the female screw part of the main body part 53, and the slide member 51 and the push-out operation part 57 are fixed to the rear shaft 24. That is, the slide member 51 and the push-out operation part 57 do not move in the front-rear direction relative to the rear shaft 24. In this state, the slide member 51 is prevented from moving forward and backward when writing or when the mechanical pencil 10 is transported. This prevents the writing lead 100 from unintentionally protruding or retracting. When the male screw part of the push-out operation part 57 is loosened against the female screw part of the main body part 53, a gap is created between the head 58 and the wall of the rear shaft 24 and between the main body part 53 and the wall of the rear shaft 24. This allows the slide member 51 and the push-out operation part 57 to move forward and backward relative to the rear shaft 24.

When the mechanical pencil 10 is in the restricted state, the restricting mechanism 70 restricts the retraction of the ejector pin 55. Therefore, the restricting mechanism 70 of this embodiment also has the function of preventing the writing lead 100 from retracting when writing pressure is applied to the writing lead 100 from the front.

When refilling or replacing the writing lead 100, the rear shaft 24 is removed from the front shaft 22 (see FIG. 9). In this state, a new writing lead 100 is inserted into the through hole of the stopper 48. As described above, the chuck mechanism 30 is configured to be able to hold writing leads 100 having different diameters. Therefore, it is possible to replace the writing lead 100 with another writing lead 100 having a different diameter without replacing the parts that make up the mechanical pencil 10.

When the rear shaft 24 is removed from the front shaft 22, if the slide member 51 is positioned forward, the ejection pin 55 remains protruding from the front end of the rear shaft 24, as shown in FIG. 10. In this case, there is a risk that the ejection pin 55 protruding from the rear shaft 24 may come into contact with other members and bend or break. In the mechanical pencil 10 of this embodiment, the retraction mechanism 60 allows the ejection pin 55 to retract. This makes it possible to prevent the ejection pin 55 protruding from the rear shaft 24 from coming into contact with other members and bending or breaking.

The mechanical pencil 10 of this embodiment has an ejector pin 55 that pushes the writing lead 100 forward, and has a retraction mechanism 60 that includes an elastic member 62 and retracts the ejector pin 55 by the elastic force of the elastic member 62.

In the mechanical pencil 10 of this embodiment, the elastic member 62 is a spiral spring 62.

When the rear shaft 24 is removed from the front shaft 22, if the slide member 51 is positioned forward, the ejection pin 55 remains protruding from the front end of the rear shaft 24, as shown in FIG. 10. In this case, there is a risk that the ejection pin 55 protruding from the rear shaft 24 may come into contact with other members and bend or break. In the mechanical pencil 10 of this embodiment, the retraction mechanism 60 allows the ejection pin 55 to retract. This makes it possible to prevent the ejection pin 55 protruding from the rear shaft 24 from coming into contact with other members and bending or breaking.

The mechanical pencil 10 of this embodiment further includes a restriction mechanism 70 that restricts the retraction of the ejector pin 55.

In the mechanical pencil 10 of this embodiment, the regulating mechanism 70 has a contact member 74 that can contact the spiral spring 62, and a biasing member 78 that can bias the contact member 74 toward the spiral spring 62.

There are cases where it is desired that the slide member 51 is not pulled back backward even when the slide member 51 is urged backward by the spiral spring 62. According to the mechanical pencil 10 of this embodiment, by providing the regulating mechanism 70, the slide member 51 is prevented from being pulled back backward even when the slide member 51 is urged backward by the spiral spring 62.

The mechanical pencil 10 of this embodiment further includes a switching mechanism 80 that can switch between a restricted state in which the restricting mechanism 70 restricts the retraction of the ejector pin 55 and a non-restricted state in which the restricting mechanism 70 does not restrict the retraction of the ejector pin 55.

In the mechanical pencil 10 of this embodiment, the switching mechanism 80 has a moving member 82, and the biasing member 78 is disposed between the contact member 74 and the moving member 82. In the restricted state, the moving member 82 moves closer to the spiral spring 62, so that the contact member 74 is pressed against the spiral spring 62.

With this mechanical pencil 10, the switching mechanism 80 allows the user to switch between the regulated state and the unregulated state according to their convenience. This improves user convenience.

In the mechanical pencil 10 of this embodiment, the switching mechanism 80 has an operating part 85, and when the operating part 85 is rotated to one side in the circumferential direction dc, the moving member 82 moves closer to the spiral spring 62, and when the operating part 85 is rotated to the other side in the circumferential direction dc, the moving member 82 moves away from the spiral spring 62.

With this type of mechanical pencil 10, you can easily switch between a regulated state and an unregulated state by simply rotating the operating unit 85.

In the mechanical pencil 10 of this embodiment, the biasing member 78 is a coil spring.

With this mechanical pencil 10, the contact member 74 can be pressed against the spiral spring 62 with a simple configuration. This simplifies the structure of the restriction mechanism 70.

A modified example of this embodiment will be described with reference to Figures 11 to 19. In the following description and the drawings used in the following description, parts that can be configured similarly to the above-described embodiment will be designated by the same reference numerals as those used for the corresponding parts in the above-described embodiment, and duplicate descriptions will be omitted.

Figure 11 is a perspective view showing a modified example of the retention mechanism 40. Figure 12 is a cross-sectional view showing the retention mechanism 40 of Figure 11.

In the example shown in FIG. 11, the retention mechanism 40 has two elastic bodies 42. The two elastic bodies 42 are arranged side by side in the axial direction da. A second shape retention member 146 is arranged inside the elastic body 42. In the illustrated example, three second shape retention members 146 are arranged for one elastic body 42. The second shape retention members 146 are arranged at positions between two adjacent protrusions 44 in the circumferential direction dc. Since the retention mechanism 40 has such second shape retention members 146, the elastic body 42 is prevented from deforming inward. Therefore, the shape of the elastic body 42 is more appropriately maintained.

Figure 13 is a perspective view showing another modified example of the retention mechanism 40. Figure 14 is a cross-sectional view showing the retention mechanism 40 of Figure 13.

In the example shown in FIG. 13 and FIG. 14, the contact retaining member 147 is disposed inside the elastic body 42. The contact retaining member 147 is disposed inside the protruding portion 44 of the elastic body 42. The retaining mechanism 40 has the same number of contact retaining members 147 as the number of protruding portions 44. Therefore, in the example shown in FIG. 14, the retaining mechanism 40 has three contact retaining members 147. One contact retaining member 147 is provided corresponding to one protruding portion 44. The contact retaining member 147 is disposed at a position between two adjacent second shape retaining members 146 in the circumferential direction dc.

In this modified example, three contact retaining members 147 contact the writing core 100 to retain the writing core 100. The radially outer ends of the contact retaining members 147 contact the protruding portion 44. Therefore, even in this modified example, the writing core 100 is elastically retained by the elastic body 42.

Figure 15 is a perspective view showing yet another modified example of the holding mechanism 40. Figure 16 is a cross-sectional view corresponding to line XVI-XVI in Figure 15. Figure 17 is a cross-sectional view corresponding to line XVII-XVII in Figure 15.

In the example shown in Figures 15 to 17, the base 32 of the chuck mechanism 30 extends to the rear end of the elastic body 42. In other words, the elastic body 42 is disposed outside the base 32. The base 32 is divided into three parts inside the elastic body 42, each of which constitutes a second shape retention member 146. From another perspective, in this modified example, it can also be said that the second shape retention member 146 is connected to the base 32 of the chuck mechanism 30. In particular, it can also be said that the second shape retention member 146 is formed integrally with the base 32 of the chuck mechanism 30.

The outer peripheral surface of the second shape retention member 146 (base 32) is formed with an annular groove 148 extending in the circumferential direction dc. In particular, the outer peripheral surface of the second shape retention member 146 is formed with a plurality of annular grooves 148. The plurality of grooves 148 are arranged side by side in the axial direction da. In the example shown in FIG. 15, the second shape retention member 146 has three grooves 148.

A ring-shaped groove 149 extending in the circumferential direction dc is formed on the outer peripheral surface of the contact retaining member 147. In particular, the same number of grooves 149 as the number of grooves 148 of the second shape retaining member 146 are formed on the outer peripheral surface of the contact retaining member 147. Corresponding grooves 148 and grooves 149 are arranged at the same position along the axial direction da.

An O-ring 150 extending in the circumferential direction dc is disposed inside the grooves 148 and 149. It is not necessary to dispose the O-ring 150 inside all of the grooves 148 and 149. As shown in FIG. 15, the O-ring 150 may be disposed only inside some of the grooves 148 and 149. The O-ring 150 has the function of pressing the contact retaining member 147 toward the writing core 100. This allows the contact retaining member 147 to more appropriately hold the writing core 100.

Figure 18 is a perspective view showing yet another modified example of the retention mechanism 40. Figure 19 is a cross-sectional view showing the retention mechanism 40 of Figure 18.

In the example shown in Figures 18 and 19, the holding mechanism 40 has multiple elastic bodies 42 arranged side by side along the circumferential direction dc. The multiple elastic bodies 42 may have the same shape and dimensions. The multiple elastic bodies 42 may be arranged with the same angular pitch. In the illustrated example, the holding mechanism 40 has three elastic bodies 42 arranged side by side with an angular pitch of 120 degrees in the circumferential direction dc. With such a holding mechanism 40, it is possible to properly hold the writing lead 100.

10 Mechanical pencil 20 Barrel 22 Front shaft 24 Rear shaft 26 Slit 28 Opening 29 Engagement protrusion 30 Chuck mechanism 32 Base 34 Claw member 36 Recess 38 Elastic member 40 Retention mechanism 42 Elastic body 44 Protrusion 46 Shape retention member 48 Stopper 50 Push-out mechanism 51 Slide member 53 Main body 55 Push-out pin 57 Push-out operation portion 58 Head 59 Washer 60 Retraction mechanism 62 Elastic member (spiral spring)
64 Rivet 70 Restriction mechanism 72 Frame member 74 Contact member 76 Contact surface 78 Pressing member 80 Switching mechanism 82 Moving member 84 Protrusion 85 Operation portion 86 Side wall portion 87 Groove portion 88 Pressing portion 92 First portion 94 Second portion 96 Connection portion 100 Writing core 146 Second shape maintaining member 147 Contact holding member 148 Groove 149 Groove 150 O-ring A Central axis da Axial direction dc Circumferential direction

Claims (8)

A mechanical pencil having an ejection pin that pushes the writing lead forward,
A mechanical pencil having a retraction mechanism including an elastic member and retracting the ejection pin by the elastic force of the elastic member. The mechanical pencil according to claim 1, wherein the elastic member is a spiral spring. The mechanical pencil according to claim 2, further comprising a restricting mechanism that restricts the retraction of the ejector pin. The regulating mechanism is
A contact member capable of contacting the spiral spring;
The mechanical pencil according to claim 3 , further comprising: a biasing member capable of biasing the contact member toward the spiral spring. The mechanical pencil according to claim 4, further comprising a switching mechanism that can switch between a restricted state in which the restricting mechanism restricts the retraction of the ejector pin and a non-restricted state in which the restricting mechanism does not restrict the retraction of the ejector pin. The switching mechanism has a moving member,
The biasing member is disposed between the contact member and the moving member,
The mechanical pencil according to claim 5 , wherein in the restricted state, the moving member moves toward the spiral spring, thereby pressing the contact member against the spiral spring. The switching mechanism has an operation unit,
When the operating portion is rotated in one circumferential direction, the moving member moves toward the spiral spring,
The mechanical pencil according to claim 6 , wherein when the operating portion is rotated to the other side in the circumferential direction, the moving member moves so as to move away from the spiral spring. The mechanical pencil according to any one of claims 4 to 6, wherein the biasing member is a coil spring.