Propelling pencil

Abstract

A mechanical pencil (1) is provided with: a pencil holder (5) having a front pencil holder (2) and a rear pencil holder (3), each of which has a tip opening (2a) through which a pencil lead can protrude; a rotating member having a chuck unit (10) that allows forward movement of the refill and prevents backward movement of the refill, a relay member (9) that surrounds the chuck unit, and a slider (7); and a rotation driving mechanism (30) that has a rotating body (40) that drives the rotating body to rotate in one direction by receiving a backward movement in the axial direction due to writing pressure received by the refill held by the chuck unit and a forward movement in the axial direction due to release of the writing pressure, the rotating body being connected to the rear end of the relay member, and the rotation driving mechanism (30) being configured to drive the rotating body to rotate in the other direction by receiving the backward movement in the axial direction due to the writing pressure received by the refill held by the chuck unit. The sliding piece is detachably connected with the front end part of the relay component, the rotating component receives the rotating driving force of the rotating body to rotate, so that the lead held by the chuck unit rotates, and the front penholder is formed by a single part.

Description

Technical Field

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

[0002] There is known a mechanical pencil configured to include: a pen barrel having a front pen barrel and a rear pen barrel detachably connectable to the rear end portion of the front pen barrel; a rotating member having a chuck unit that allows the advancement of a refill and prevents the retreat of the refill, a relay member surrounding the chuck unit, and a slider; and a rotation drive mechanism having a rotating body, receiving a retreat action in the axial direction generated by a writing pressure applied to the refill held by the chuck unit and an advancement action in the axial direction generated by the release of the writing pressure, and driving the rotating body to rotate in one direction. The rotating body is connected to the rear end portion of the relay member, the slider is detachably connected to the front end portion of the relay member, and the rotating member rotates by receiving the rotational driving force of the rotating body, so that the refill held by the chuck unit rotates (Patent Document 1). In the mechanical pencil described in Patent Document 1, a tip sleeve member formed in a substantially conical shape as a separate component is screwed to the front end portion of a cylindrical front pen barrel having substantially the same outer diameter.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013 - 107263 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In addition, in a mechanical pencil, there is a case where the refill is broken inside the mechanical pencil due to an impact during dropping or the like. In order to continue using the mechanical pencil, it is necessary to take out the refill that has become short due to breakage or other reasons and remains inside the mechanical pencil and cannot be sent out by pressing operation.

[0008] In the mechanical pencil described in Patent Document 1, in order to take out the refill that is located inside the slider and cannot be sent out due to the shortening of the core portion or the like, it is necessary to remove the tip sleeve member from the front pen barrel and then remove the slider from the relay member. Since the slider has a relatively short length in the axial direction with respect to the overall length of the mechanical pencil, it is relatively difficult to hold.

[0009] Assume that when the slider is firmly engaged with the relay member, even if an attempt is made to remove the slider while twisting it relative to the relay member, due to the structure of the rotary drive mechanism, the relay member itself will rotate together with the slider, making it difficult to remove the slider. In addition, in the case of a mechanical pencil equipped with a rotary drive mechanism where the slider and the relay member are not engaged but threadedly coupled, since the relay member itself rotates together with the slider, it is difficult to release the threaded coupling, and thus it is even more difficult to remove the slider. In these cases, by using a pressing operation to maintain the state of pressing the operation portion disposed at the rear end portion of the mechanical pencil forward, rotation of the relay member can be suppressed. However, it is not easy to achieve good maintainability by rotating the slider with one hand while maintaining the state of pressing the operation portion with the other hand.

[0010] In addition, even if not only the tip member is removed, but an attempt is made to remove the front barrel from the rear barrel, exposing the relay member and directly gripping it to rotate and remove the slider, there is a concern that a part or all of the structural components of the rotary drive mechanism disposed within the rear barrel may fall off from the rear barrel. If a part or all of the structural components fall off, there is a concern about loss of the structural components and assembly errors, which is not ideal.

[0011] An object of the present invention is to provide a mechanical pencil with improved maintainability against breakage of the lead and the like.

[0012] Solution to the problem

[0013] According to one aspect of the present invention, there is provided a mechanical pencil, characterized in that the mechanical pencil includes: a barrel having a front barrel with a front end opening through which a lead can protrude and a rear barrel detachably connected to the rear end portion of the front barrel; a rotary member having a chuck unit that allows the lead to advance and prevents the lead from retracting, a relay member surrounding the chuck unit, and a slider; and a rotary drive mechanism having a rotating body, the rotary drive mechanism receiving a rearward movement in the axial direction generated by a writing pressure applied to the lead held by the chuck unit and a forward movement in the axial direction generated by the release of the writing pressure, and driving the rotating body to rotate in one direction, the rotating body being connected to the rear end portion of the relay member, the slider being detachably connected to the front end portion of the relay member, and the mechanical pencil being configured such that the rotary member rotates by receiving the rotational driving force of the rotating body, so that the lead held by the chuck unit rotates, and the front barrel is formed of a single member.

[0014] Alternatively, the rotation drive mechanism may be disposed within the rear pen barrel, and the mechanical pencil may include a support member configured to prevent the rotation drive mechanism from detaching from the rear pen barrel when the front pen barrel is removed. Alternatively, an internal thread may be formed on the sliding member, and an external thread may be formed on the relay member, and the sliding member and the relay member may be detachably connected by screw engagement.

[0015] Effects of the Invention

[0016] According to the technical solution of the present invention, there is a common effect of providing a mechanical pencil with improved maintainability against breakage of the refill and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a longitudinal sectional view of a mechanical pencil according to an embodiment of the present invention.

[0018] Figure 2 is Figure 1 an enlarged sectional view of the front half of the mechanical pencil.

[0019] Figure 3 is Figure 1 an enlarged sectional view of the central portion of the mechanical pencil.

[0020] Figure 4 is a schematic diagram illustrating the rotational drive of the rotating body of the rotation drive mechanism.

[0021] Figure 5 is Figure 4 a schematic diagram illustrating the rotational drive of the rotating body following

[0022] Figure 6 is a perspective view of the mechanical pencil Figure 1 in a state where the front pen barrel is removed.

[0023] Figure 7 is Figure 6 a perspective view of the mechanical pencil Figure 1 in a state where the sliding member is further removed from the state shown in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings, common reference numerals are assigned to corresponding structural elements.

[0025] Figure 1 is a longitudinal sectional view of a mechanical pencil 1 according to an embodiment of the present invention, Figure 2 is Figure 1 an enlarged sectional view of the front half of the mechanical pencil 1.

[0026] The mechanical pencil 1 has a front barrel 2, a rear barrel 3 that is detachably threadedly coupled to the outer peripheral surface of the rear end portion of the front barrel 2, and an inner cylinder 4 that is fitted into the inner peripheral surface of the rear end portion of the rear barrel 3 and has a clip. The front barrel 2 and the rear barrel 3 constitute a barrel 5. In addition, the barrel 5 may also be referred to as including the inner cylinder 4. The mechanical pencil 1 is configured such that the lead projects from the tip of the barrel 5. Specifically, it is configured such that the lead can project from the front end opening 2a of the front barrel 2. In this specification, in the axial direction of the mechanical pencil 1, the lead side is defined as the "front" side, and the side opposite to the lead side is defined as the "rear" side.

[0027] The front barrel 2 is a cylindrical member formed with a substantially identical outer shape, and the vicinity of the front end portion is formed in a substantially conical shape. A front end opening 2a is formed at the front end portion of the front barrel 2. Thus, the outer shape of the front barrel 2 is the same as that of the front barrel of a conventional mechanical pencil. The front barrel 2 has a grip portion 2b formed of a material softer than the front barrel 2 so that the user can easily grip the mechanical pencil 1. Inside the front end portion of the front barrel 2, a slider 7 having a tip tube 6 for guiding the lead is disposed so as to be slidable in the axial direction and rotatable about the axis.

[0028] The slider 7 is formed in a cylindrical shape with an outer diameter that tapers stepwise toward the front. The front end portion of the slider 7 projects from the front end opening 2a of the front barrel 2 together with the tip tube 6. Behind the tip tube 6 inside the slider 7, a holding chuck 8 having a through hole formed in the center is disposed. The through hole of the holding chuck 8 is in sliding contact with the outer peripheral surface of the lead and functions to temporarily hold the lead.

[0029] A relay member 9 formed in a cylindrical shape is threadedly coupled to the rear end portion of the slider 7. That is, an internal thread 7a is formed on the inner peripheral surface of the rear end portion of the slider 7, and an external thread 9a is formed on the outer peripheral surface of the front end portion of the relay member 9. A chuck unit 10 for gripping the lead and a lead case 13 are disposed inside the slider 7 and the relay member 9. The chuck unit 10 has a chuck main body portion 11 and a fastener 12 formed in a cylindrical shape so as to surround the front end portion of the chuck main body portion 11. At least the front half portion of the chuck main body portion 11 is divided into three chuck pieces 11a along the axial direction, and a through hole for the lead is formed along the central axis. The chuck pieces 11a are each formed such that their front end portions are separated from each other. The lead case 13 is formed in a cylindrical shape and houses the lead inside. The rear end portion of the chuck main body portion 11 is inserted and fitted into the inside of the front end portion of the lead case 13.

[0030] A coil spring 14 is disposed so as to surround the chuck body portion 11. The front end of the coil spring 14 is supported by a stepped portion formed on the inner peripheral surface of the relay member 9, and the rear end of the coil spring 14 abuts against the front end surface of the refill housing 13. Accordingly, the coil spring 14 biases the refill housing 13 and the chuck body portion 11 rearward. The chuck body portion 11 biased rearward is received in the fastener 12, and the front end portions thereof approach each other, and the state of holding the refill can be maintained. Further, when a writing pressure is applied to the refill, the chuck body portion 11 further retracts and is received in the fastener 12, and the refill is held by the chuck body portion 11. Thereby, the retraction of the refill is prevented. On the other hand, when a force for pulling the refill forward acts, since the chuck body portion 11 is not affected by the fastener 12, the refill can be pulled forward without resistance. That is, the chuck unit 10 functions to allow the forward movement of the refill and prevent the backward movement of the refill, but as long as this function is achieved, it may be other chuck units, such as a ball chuck.

[0031] The outer peripheral surface of the fastener 12 is fitted into the inner peripheral surface of the front end portion of the relay member 9. Accordingly, the slider 7, the relay member 9, and the chuck unit 10 can move in the axial direction within the pen barrel 5. The rear end portion of the relay member 9 is connected to a rotation drive mechanism 30 described later.

[0032] A cylindrical pressing member 20 as a pressing member is provided at the rear end portion of the pen barrel 5, specifically, at the rear end portion of the inner cylinder 4 so as to be movable back and forth relative to the pen barrel 5. The pressing member 20 is biased rearward by a coil spring 21. The refill housing 13 is inserted into the front end portion of the pressing member 20. An eraser 22 is detachably mounted inside the rear end portion of the pressing member 20. A pressing cap 23 is detachably mounted on the outer peripheral surface of the rear end portion of the pressing member 20, and the pressing cap 23 protects the eraser 22 from contamination and the like.

[0033] By performing a pressing operation of pressing the pressing member 20 or the pressing cap 23 forward, the refill housing 13 advances. Accordingly, the chuck body portion 11 is pushed forward. Along with this, the refill held by the chuck body portion 11 also advances, and functions to send out the refill from the tip tube 6. When the pressing of the pressing operation is released, the pressing member 20 retracts to the original position by the action of the coil spring 21. At this time, the chuck body portion 11 retracts by the action of the coil spring 14. On the other hand, since the refill is held by the holding chuck 8 disposed in the slider 7, as a function of the chuck unit 10, the refill is pulled out from the chuck body portion 11 without resistance. As a result, the refill is sent out from the tip tube 6, and thus, each time the pressing operation is repeated, the refill can be sent out successively by a predetermined amount.

[0034] Figure 3 is Figure 1An enlarged cross-sectional view of the central portion of the mechanical pencil 1. The rotation drive mechanism 30 is disposed in the internal space of the rear pen barrel 3. The rotation drive mechanism 30 is connected to the rear end portion of the relay member 9. The refill housing 13 passes through the relay member 9 and the inside of the rotation drive mechanism 30, and the refill housing 13 is separated from the rotation drive mechanism 30. The rotation drive mechanism 30 is biased rearward by the shaft spring 31. That is, the front end of the shaft spring 31 is supported by the support member 32 formed in a cylindrical shape, and the rear end of the shaft spring 31 is supported by the front end surface of the rotation drive mechanism 30, so that the rotation drive mechanism 30 is biased rearward.

[0035] The support member 32 has a rearward-facing annular support surface 32a formed by protrusions provided on the inner peripheral surface and a locking protrusion 32b provided in an annular shape on the outer peripheral surface of the rear end portion. As described above, the support surface 32a is configured to support the front end of the shaft spring 31. The locking protrusion 32b is configured to be locked to the annular convex portion 3a provided on the inner peripheral surface of the rear pen barrel 3. That is, during the assembly of the mechanical pencil 1, after the rotation drive mechanism 30 is disposed in the rear pen barrel 3, the support member 32 is inserted into the rear pen barrel 3. At this time, the locking protrusion 32b of the support member 32 passes over the convex portion 3a of the rear pen barrel 3 by elastic deformation, and the locking protrusion 32b and the convex portion 3a are in a locked state. As a result, the forward movement of the support member 32 is restricted, and the support member 32 is fixed near the open end of the rear end of the rear pen barrel 3.

[0036] The rotation drive mechanism 30 includes a cylindrical rotating body 40, a cylindrical upper cam forming member 41 as a first cam forming member, a cylindrical lower cam forming member 42 as a second cam forming member, a cylindrical cylinder member 43, a cylindrical torque eliminator 44, and a spiral buffer spring 45. These members of the rotation drive mechanism 30 are integrated and unitized.

[0037] The outer peripheral surface of the rear end portion of the relay member 9 is fitted into the inner peripheral surface of the front end portion of the rotating body 40. Near the front end portion of the rotating body 40, there is a flange-shaped portion with a slightly larger diameter. A first cam surface 40a is formed on the rear end surface of this portion, and a second cam surface 40b is formed on the front end surface of this portion.

[0038] The upper cam forming member 41 surrounds the rotating body 40 in a rotatable manner behind the first cam surface 40a of the rotating body 40. The lower cam forming member 42 is fitted onto the outer peripheral surface of the front end portion of the upper cam forming member 41. A first fixed cam surface 41a is formed on the front end surface of the upper cam forming member 41 that faces the first cam surface 40a of the rotating body 40. A second fixed cam surface 42a is formed on the inner surface of the front end portion of the lower cam forming member 42 that faces the second cam surface 40b of the rotating body 40.

[0039] The cylinder member 43 formed in a cylindrical shape is fitted to the outer peripheral surface of the rear end portion of the upper cam forming member 41. A through hole 43a through which the refill case 13 can pass is formed at the rear end portion of the cylinder member 43. A torque canceller 44 formed in a cylindrical shape and movable in the axial direction is arranged in the cylinder member 43. A buffer spring 45 is arranged between the inner surface of the front end portion of the torque canceller 44 and the inner surface of the rear end portion of the cylinder member 43. The buffer spring 45 applies force to the rotating body 40 forward via the torque canceller 44.

[0040] Here, the relay member 9 transmits the backward movement and forward movement (buffering movement) of the writing lead based on the writing movement to the rotation drive mechanism 30, that is, the rotating body 40, and the relay member 9 transmits the rotational motion of the rotating body 40 of the rotation drive mechanism 30 caused by the buffering movement to the chuck unit 10 in the state of holding the writing lead. Therefore, the writing lead held by the chuck unit 10 is also rotated by the rotation of the relay member 9.

[0041] When writing is not performed with the mechanical pencil 1, that is, when writing pressure is not applied to the lead, the rotating body 40 is located forward by the force of the buffer spring 45 through the torque canceller 44. Therefore, the second cam surface 40b of the rotating body 40 abuts against the second fixed cam surface 42a and is in meshing state. When writing is performed with the mechanical pencil 1, that is, when writing pressure is applied to the lead, the chuck unit 10 overcomes the force of the buffer spring 45 and retreats, and the rotating body 40 also retreats. Therefore, the first cam surface 40a of the rotating body 40 abuts against the first fixed cam surface 41a and is in meshing state. The lead and the rotating body 40 move forward, retreat or rotate integrally.

[0042] Figure 4 3 is a schematic diagram for explaining the rotational drive of the rotating body 40 of the rotational drive mechanism 30. Figure 5 Then Figure 4 Schematic diagram of the description of the rotational drive of the rotating body 40. Figure 4 and Figure 5 In the figure, a first cam surface 40a is formed in a circular ring shape on the upper side surface, i.e., the rear end surface, of the rotating body 40, and a second cam surface 40b is formed in a circular ring shape on the lower side surface, i.e., the front end surface, and a second cam surface 40b is formed in a circular ring shape, which is continuously serrated along the circumferential direction.

[0043] On the annular end face of the upper cam forming member 41 that faces the first cam surface 40a of the rotating body 40, a first fixed cam surface 41a that is continuously serrated along the circumferential direction is also formed. On the annular end face of the lower cam forming member 42 that faces the second cam surface 40b of the rotating body 40, a second fixed cam surface 42a that is continuously serrated along the circumferential direction is also formed. Each of the cam surfaces formed on the first cam surface 40a and the second cam surface 40b of the rotating body 40 and each of the cam surfaces formed on the first fixed cam surface 41a of the upper cam forming member 41 and the second fixed cam surface 42a of the lower cam forming member 42 are formed such that their pitches are substantially the same as each other.

[0044] Figure 4 (A) of shows the relationship among the advanced rotating body 40, the upper cam forming member 41, and the lower cam forming member 42 in a state where no writing pressure is applied to the refill. In this state, the second cam surface 40b formed on the rotating body 40 abuts against the second fixed cam surface 42a of the lower cam forming member 42 under the action of the buffer spring 45. At this time, the first cam surface 40a of the rotating body 40 and the first fixed cam surface 41a of the upper cam forming member 41 are set to have a relationship in which they are offset by half a phase (half a pitch) with respect to one tooth of the cam in the axial direction.

[0045] Figure 4 (B) of shows the initial state in which writing pressure is applied to the refill due to writing with the mechanical pencil 1. In this state, the rotating body 40 retreats with the contraction of the buffer spring 45 as the chuck unit 10 retreats. As a result, the rotating body 40 moves toward the upper cam forming member 41 side and abuts against the first fixed cam surface 41a.

[0046] Next, Figure 4 (C) of shows a state in which further writing pressure is applied to the refill and the rotating body 40 slides while abutting against the first fixed cam surface 41a of the upper cam forming member 41 and then retreats. That is, the rotating body 40 receives a rotational drive corresponding to half a phase (half a pitch) of one tooth of the first cam surface 40a. In this state, the first cam surface 40a of the rotating body 40 meshes with the first fixed cam surface 41a of the upper cam forming member 41.

[0047] In addition, in Figure 4 and Figure 5 , the ○ mark depicted at the center of the rotating body 40 indicates the rotational movement amount of the rotating body 40. Then, in the state shown in (C) of Figure 4 , the second cam surface 40b of the rotating body 40 and the second fixed cam surface 42a of the lower cam forming member 42 are set to have a relationship in which they are offset by half a phase (half a pitch) with respect to one tooth of the cam in the axial direction.

[0048] Next, Figure 5 (D) of Figure 5 shows an initial state in which writing with the mechanical pencil 1 is completed and the writing pressure on the lead is released. In this state, the rotating body 40 advances under the action of the buffer spring 45. As a result, the rotating body 40 moves toward the lower cam forming member 42 and abuts against the second fixed cam surface 42a.

[0049] Next, Figure 5 (E) of Figure 5 shows a state in which the rotating body 40 slides and advances while abutting against the second fixed cam surface 42a of the lower cam forming member 42 under the action of the buffer spring 45. That is, the rotating body 40 receives a rotational drive corresponding to half a phase (half a pitch) of one tooth of the second cam surface 40b again. In this state, the second cam surface 40b of the rotating body 40 meshes with the second fixed cam surface 42a of the lower cam forming member 42.

[0050] Therefore, as shown by the ○ mark drawn at the center of the rotating body 40 in Figure 4 and Figure 5 With the reciprocating movement, i.e., the forward and backward movement, of the rotating body 40 in the axial direction under the writing pressure, the rotating body 40 receives a rotational drive corresponding to one tooth (one pitch) of the first cam surface 40a and the second cam surface 40b. With the collet unit 10, the lead held by the collet unit 10 is also rotationally driven in the same manner. Therefore, with one forward and backward movement of the rotating body 40 in the axial direction generated by writing, the rotating body 40 receives a rotational movement corresponding to one tooth of the cam, and by repeating the above actions, the lead is sequentially rotationally driven. As a result, it is possible to prevent the uneven wear of the lead as writing progresses and to prevent significant variations in the thickness and depth of the writing line.

[0051] In addition, the torque eliminator 44 that pushes the rotating body 40 forward under the action of the buffer spring 45 generates sliding between the front end surface of the torque eliminator 44 and the rear end surface of the rotating body 40, thereby preventing the rotational movement of the rotating body 40 from being transmitted to the buffer spring 45. That is, with the torque eliminator 44, the rotational movement of the rotating body 40 is prevented from being transmitted to the buffer spring 45, and thereby, the buffer spring 45 is prevented from generating a reverse torsion (torque) that hinders the rotational movement of the rotating body 40.

[0052] As described above, the mechanical pencil 1 includes: a rotating member having a chuck unit 10 that allows the lead to advance and prevents the lead from retracting, a relay member 9 that surrounds the chuck unit 10, and a slider 7; and a rotation driving mechanism 30 having a rotating body 40. The rotation driving mechanism 30 receives a backward movement in the axial direction generated by the writing pressure applied to the lead held by the chuck unit 10 and a forward movement in the axial direction generated by the release of the writing pressure, and drives the rotating body 40 to rotate in one direction. Further, the rotating body 40 is connected to the rear end portion of the relay member 9, and the slider 7 is detachably connected to the front end portion of the relay member 9. The mechanical pencil 1 is configured such that the rotating member rotates by receiving the rotational driving force of the rotating body 40, so that the lead held by the chuck unit 10 rotates.

[0053] Figure 6 is a state in which the front pen barrel 2 is removed Figure 1 of the mechanical pencil 1, Figure 7 is from Figure 6 the state shown and further removed the slider 7 Figure 1 of the mechanical pencil 1.

[0054] In the mechanical pencil 1, in order to take out the lead that is located inside the slider 7 and cannot be sent out due to the shortening of the core part, etc., the front pen barrel 2 is detached from the rear pen barrel 3 ( Figure 6 ). Then, hold the relay member 9 and rotate the slider 7 to release the screw engagement ( Figure 7 ). Thus, the user can access the inside of the chuck unit 10 and the slider 7, and can take out the lead located inside the slider 7.

[0055] In the mechanical pencil 1, the front pen barrel 2 is composed of a single part from the front opening 2a where the lead can protrude to the rear opening connected to the rear pen barrel 3. Therefore, by simply detaching the front pen barrel 2 from the rear pen barrel 3, the relay member 9 can be exposed with a sufficient length in the axial direction. Then, the user can rotate the slider 7 while directly holding the exposed relay member 9, so that the slider 7 can be easily detached. Thus, according to the mechanical pencil 1, the maintainability against lead breakage, etc. can be improved.

[0056] Further, a support member 32 is disposed near the opening end of the rear pen barrel 3. Therefore, even in a state where the front pen barrel 2 is detached from the rear pen barrel 3, a part or all of the structural components of the rotation driving mechanism 30 can be prevented from falling off from the rear pen barrel 3. Thereby, loss of the structural components of the rotation driving mechanism 30, etc. is prevented.

[0057] Here, in the case of a structure in which a tip member is connected to a front pen barrel as in a conventional mechanical pencil, the internal space near the connection portion is narrowed by an amount corresponding to the thickness of the two members overlapping in the radial direction due to the fitting or screw connection at the connection portion. As a result, it is necessary to reduce the outer diameter of the portion of the slider corresponding to the connection portion, and thus, it becomes more difficult to hold the slider.

[0058] On the other hand, in the mechanical pencil 1 according to the embodiment of the present invention, the front pen barrel 2 is composed of a single member, and the front pen barrel 2 is configured to surround not only the relay member 9 but also the slider 7. In the mechanical pencil 1, since there is no connection portion as in a conventional mechanical pencil, the space around the slider 7 can be expanded compared to the conventional case, and the outer diameter of the slider 7 can be further increased. As a result, it is easier to hold when removing the slider 7.

[0059] In the case where the slider and the relay member are connected by fitting instead of screw connection as in the mechanical pencil described in Patent Document 1, considering maintainability against breakage of the lead, etc., too strong fitting is not ideal. On the other hand, if a certain degree of loose fitting is provided, the lead will not be reliably held during writing and will shake, thus impairing the writing feeling of the user. That is, due to the friction between the writing surface during writing, the lead is subjected to a radial force, and in contrast, the tip tube and the slider are also subjected to a radial force. At this time, if the fitting between the slider and the relay member is loose, the slider will move radially with respect to the relay member, and for the user who holds the relay member via the pen barrel, the lead will be felt to shake. This shaking becomes a cause of impairing the writing feeling.

[0060] On the other hand, in the mechanical pencil 1 according to the embodiment of the present invention, the slider 7 and the relay member 9 are connected by screw connection. Therefore, compared with the case where the slider and the relay member are connected by fitting as in the mechanical pencil described in Patent Document 1, a more firm connection can be established without impairing the writing feeling.

[0061] Moreover, in the mechanical pencil 1, an internal thread 7a is formed on the inner peripheral surface of the rear end portion of the slider 7, and an external thread 9a is formed on the outer peripheral surface of the front end portion of the relay member 9. Therefore, compared with the case where an external thread portion is formed on the slider and an internal thread is formed on the relay member, the outer diameter of the slider can be further increased. As a result, it is easier to hold when removing the slider 7.

[0062] In addition, since the front pen barrel 2 is composed of a single member, in particular, the internal space of the front end portion can be expanded compared to the conventional case. Therefore, the axial length of the internal thread of the slider 7 and the external thread of the relay member 9 can be made longer, and a more reliable connection can be achieved. Since a longer connection portion can be ensured, the slider and the relay member can also be connected by fitting instead of screw connection.

[0063] In the above-described embodiments, a mechanical pencil having a rotation drive mechanism has been described. However, the embodiments of the present invention can also be applied to a mechanical pencil that does not have a rotation drive mechanism and has a detachable slider in front of the chuck unit.

[0064] Description of Reference Numerals

[0065] 1. Mechanical pencil; 2. Front pen barrel; 2a. Front end opening; 2b. Gripping portion; 3. Rear pen barrel; 4. Inner cylinder; 5. Pen barrel; 6. Tip tube; 7. Slider; 8. Holding chuck; 9. Relay member; 10. Chuck unit; 11. Chuck main body portion; 13. Lead case; 14. Helical spring; 20. Pushing member; 21. Helical spring; 22. Eraser; 23. Pushing cap; 30. Rotation drive mechanism; 31. Shaft spring; 32. Support member; 40. Rotating body.

Claims

1. An automatic pencil, characterized in that, The automatic pencil comprises: A pen barrel, which has a front pen barrel with a front end opening capable of allowing the lead to protrude and a rear pen barrel detachably connected to the rear end of the front pen barrel; A rotating member, which has a chuck unit that allows the lead to advance and prevents the lead from retracting, a relay member surrounding the chuck unit, and a slider; And A rotary drive mechanism, which has a rotating body. The rotary drive mechanism receives the backward movement in the axial direction generated by the writing pressure borne by the lead held by the chuck unit and the forward movement in the axial direction generated by the release of the writing pressure, and drives the rotating body to rotate in one direction. The rotating body is connected to the rear end of the relay member, and the slider is detachably connected to the front end of the relay member. The automatic pencil is configured such that the rotating member rotates by receiving the rotational driving force of the rotating body, so that the lead held by the chuck unit rotates. The front pen barrel is composed of a single part.

2. The automatic pencil according to claim 1, wherein The rotary drive mechanism is disposed in the rear pen barrel, and the automatic pencil has a support member configured to prevent the rotary drive mechanism from falling off the rear pen barrel in a state where the front pen barrel is removed.

3. The automatic pencil according to claim 1 or 2, wherein An internal thread is formed on the slider, and an external thread is formed on the relay member. The slider and the relay member are detachably connected by screw engagement.

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