Pendulum-type writing instrument

Abstract

To provide a pendulum-type writing instrument which can prevent the lead from being advanced due to a knocking action when an eraser is used, without incorporating a heavy-load spring at the rear end side of a cylindrical body constituting the writing instrument.SOLUTION: Provided is a pendulum-type writing instrument including an eraser holder 29 that supports the eraser at its rear end, an actuation guide groove 50a, a pendulum 24, and an actuation protrusion 35a. The pendulum side hook portion provided at the rear end of the pendulum 24 engages with the eraser holder side hook portion provided at the tip of the eraser holder 29, allowing the eraser to be used with strong force.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This invention relates to a pendulum-type writing instrument.

Background Art

[0002] By swinging a cylindrical shaft tube in the direction in which the shaft tube extends, or moving the cylindrical shaft tube in the vertical direction, which is the direction in which the shaft tube extends, a pendulum (weight, heavy object, etc.) housed in the shaft tube is moved in the direction in which the shaft tube extends, and the inertial force is applied to a chuck built into the tip side of the shaft tube, so that a writing instrument that feeds out a core built into the shaft tube from the tip of the shaft tube has been conventionally known, and is called a pendulum-type writing instrument, a retractable writing instrument, etc.

[0003] Various proposals have been made for pendulum-type writing instruments (for example, Patent Documents 1, 2, and 3).

[0004] A conventional general structure of a pendulum-type writing instrument will be described with reference to FIG. 1. In the conventional pendulum-type writing instrument 12 illustrated in FIG. 1, a chuck guide 5 that constitutes a chuck mechanism is provided inside the tip side of a cylindrical main body 1 that constitutes the shaft tube and has a taper 2 at the tip (the left end in FIG. 1), and a tail plug 6 is provided inside the rear end side (the right side in FIG. 1). A pendulum 4 having a predetermined weight is provided between the chuck guide 5 and the tail plug 6 inside the main body 1. The pendulum 4 is configured as, for example, a metal weight. The pendulum 4 is movable between the chuck guide 5 and the tail plug 6 in the direction in which the main body 1 extends (the left-right direction in FIG. 1). In the embodiment of FIG. 1, the pendulum 4 is also rotatable around the central axis of the cylindrical main body 1.

[0005] When writing with the pendulum type writing instrument 12 and swinging the pendulum type writing instrument 12 up and down by hand, that is, swinging it in the left - right direction of FIG. 1, the pendulum 4 reciprocates between the chuck guide 5 and the tail plug 6 and collides with the chuck guide 5 in the forward direction from the right side to the left side of FIG. 1. When the inertia force is applied by the pendulum 4 colliding with the chuck guide 5 in this way, the chuck guide 5 moves forward in the tip direction of the main body 1 (the left - hand direction of FIG. 1). Then, the chuck attached to the chuck guide 5 operates, and the tip of the refill 11 housed in the refill tank 3 is fed out from the tip of the main body 1 where the taper 2 is formed (the left end of FIG. 1).

[0006] In such a general pendulum type writing instrument 12, the load of the spring 7 arranged on the chuck guide 5 side in the main body 1 is set not to be too large in consideration of the above - mentioned forward movement caused by the collision of the pendulum 4 with the chuck guide 5. For example, a spring 7 with a load of about 0.98N - 1.96N is generally adopted.

[0007] As shown in FIG. 1, in the case of the pendulum type writing instrument 12 where the eraser 8 supported by the eraser holder 9 is arranged on the rear - end side of the main body 1, when using the eraser 8, it is turned upside down from the writing state and the rear end of the eraser 8 (the right - hand end of FIG. 1) is rubbed against the paper surface. At this time, if the load of the spring 7 mentioned above is not large, a knocking operation will occur every time the rubbing operation using the eraser 8 is performed, the chuck will operate as described above, and the refill 11 will be fed out.

[0008] For the purpose of preventing such a situation from occurring, a structure and configuration in which a spring 10 having a large and strong load, larger than the load of the spring 7 on the tip side, is arranged inside the rear - end side (the right side of FIG. 1) of the main body 1 as shown in FIG. 1 is generally adopted. In the embodiment shown in FIG. 1, a spring 10 having a strong load is arranged inside the rear - end side (the right side of FIG. 1) of the main body 1 via the spring receiver 8. For example, a spring 10 with a load of about 2.94N - 5.88N is generally adopted.

[0009] By arranging such a strong spring 10 as shown in Fig. 1, when the eraser 8 is used, it becomes difficult for the chuck to operate.

[0010] By adopting the structure and configuration as shown in Fig. 1, when the eraser 8 is used, the eraser holder 9 is supported by the strong spring 10, and it becomes difficult for the eraser holder 9 to sink even when the eraser 8 is used. That is, even when the eraser 8 is used, the eraser holder 9 is difficult to move in the left direction of Fig. 1, and the eraser 8 can be used without causing a situation where a knocking operation occurs and the lead 11 is fed out every time the above-mentioned rubbing operation is performed using the eraser 8.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0012] In a pendulum-type writing instrument having an eraser at the rear end side, for the purpose of preventing a situation where a knocking operation occurs and the lead is fed out when the eraser is used, when trying to incorporate a strong spring inside the rear end side of the cylindrical body constituting the writing instrument, generally the number of parts increases and the cost becomes high.

[0013] Therefore, an object of the present invention is to provide a pendulum-type writing instrument having an eraser at the rear end side, which can prevent a situation where a knocking operation occurs and the core is fed out when using the eraser without incorporating a spring with a strong load on the rear end side of the cylindrical body constituting the writing instrument.

Means for Solving the Problems

[0014] In the pendulum-type writing instrument of the present invention, the pendulum built into the main body can move in the front-rear direction between the front end side of the main body where the chuck mechanism is provided and the rear end side of the main body where the eraser is provided, but cannot move in the circumferential direction around the central axis of the main body.

[0015] On the other hand, the eraser holder that supports the eraser on the rear end side is fitted to the rear end of the main body so as to be movable in the front-rear direction and the circumferential direction.

[0016] The main body is provided with an operation guide groove that penetrates the peripheral wall in the radial direction on the rear end side. The operation guide groove consists of a knock groove portion that extends in the front-rear direction and a retraction groove portion that is continuous with the knock groove portion and extends obliquely from the rear end of the knock groove portion toward the rear end of the main body with respect to the direction in which the knock groove portion extends.

[0017] The eraser holder is provided with an operation convex portion that protrudes from the inside to the outside in the radial direction of the operation guide groove. The movement of the eraser holder in the front-rear direction and the circumferential direction is guided by the movement of the operation convex portion in the operation guide groove.

[0018] When the pendulum moves backward as when using the eraser, and the rear end portion of the pendulum contacts the front end portion of the eraser holder, and a force in the backward direction is applied from the pendulum to the eraser holder, the eraser holder moves in the circumferential direction, so that the operation convex portion moves from the knock groove portion to the retraction groove portion, and the pendulum-side latching portion provided at the rear end portion of the pendulum and the eraser-holder-side engaging portion provided at the front end portion of the eraser holder are engaged with each other.

[0019] When the engagement between the pendulum side engaging portion and the eraser holder side engaging portion is performed, the eraser holder cannot move in the circumferential direction, and the actuating convex portion cannot return from the retracted groove portion to the knocking groove portion, so that the eraser can be used with a strong force.

[0020] When the pendulum moves forward during use of the writing instrument and the engagement with the eraser holder is released, the eraser holder can move in the circumferential direction, and the actuating convex portion moves from the retracted groove portion to the knocking groove portion so that the knocking operation can be performed.

[0021] The present invention having such a structure and configuration and achieving the above-described object can be exemplified as follows. [1] A cylindrical main body portion extending in the front-rear direction from the rear end to the front end, A core tank extending in the front-rear direction and disposed inside the main body portion, A pendulum extending in the front-rear direction and disposed inside the main body portion, and being movable in the front-rear direction within the main body portion, A chuck mechanism provided on the front end side of the main body portion inside the main body portion, An eraser provided at the rear end of the main body portion A pendulum type writing instrument having a core accommodated in the core tank and being fed out from the front end, The main body portion and the pendulum are engaged by the engagement of a main body side engaging portion extending in the front-rear direction on the inner circumference of the main body portion provided in the main body portion and a pendulum side engaging portion extending in the front-rear direction on the outer circumference of the pendulum provided in the pendulum, An eraser holder that supports the eraser on the rear end side is fitted to the rear end of the main body portion so as to be movable in the front-rear direction and movable in the circumferential direction around the central axis of the main body portion, The pendulum includes a pendulum rear end portion that abuts on the eraser holder tip portion that is the tip of the eraser holder at the rear end, The pendulum and the eraser holder are provided with a pendulum-side latching portion and an eraser-holder-side engaging portion that engage with each other when the eraser holder moves in the circumferential direction with the rear end portion of the pendulum and the front end portion of the eraser holder in contact with each other and a backward force being applied from the pendulum to the eraser holder, at the rear end portion of the pendulum and the front end of the eraser holder, respectively. An operation guide groove for guiding the movement of the eraser holder in the front-rear direction and the circumferential direction is formed by penetrating the circumferential wall of the main body portion, i.e., the main body circumferential wall, in the radial direction on the rear end side of the main body portion. The operation guide groove includes a knocking groove portion extending in the front-rear direction and a retracting groove portion that is continuous with the knocking groove portion and extends obliquely from the rear end of the knocking groove portion toward the rear end of the main body portion with respect to the direction in which the knocking groove portion extends. The eraser holder is provided with an operating convex portion that protrudes from the inner side to the outer side in the radial direction of the operation guide groove. Pendulum-type writing instrument.

[0022] [2] The main body portion includes a cylindrical main body extending in the front-rear direction from the rear end to the front end and a cylindrical tail plug mounted inside the rear end of the main body. At the rear end of the tail plug, the eraser holder is fitted so as to be movable in the front-rear direction and movable in the circumferential direction around the central axis. The operation guide groove in which the operating convex portion of the eraser holder protrudes from the inner side to the outer side in the radial direction is formed by penetrating the circumferential wall of the tail plug, i.e., the tail plug circumferential wall, in the radial direction on the front end side of the tail plug. The pendulum-type writing instrument according to [1].

Effect of the Invention

[0023] According to the present invention, it is possible to provide a pendulum-type writing instrument having an eraser on the rear end side, which can prevent a situation in which a knocking operation occurs and the core is fed out when using the eraser without incorporating a spring with a strong load on the rear end side of the cylindrical main body constituting the writing instrument.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0025] Hereinafter, an example of an embodiment of the present invention will be described with reference to the accompanying drawings. In this specification, the side of the tip of the writing instrument (the left end in the pendulum-type writing instrument 11 of FIG. 1) is referred to as the tip side, the side of the rear end of the writing instrument (the right end in the pendulum-type writing instrument 11 of FIG. 1) is referred to as the rear end side, the direction from the rear end to the front end and the direction from the front end to the rear end are referred to as the front-rear direction, the direction from the rear end side to the front end side is referred to as the forward direction, and the direction from the front end side to the rear end side is referred to as the backward direction for explanation.

[0026] The basic configuration of the pendulum-type writing instrument 20 of the embodiment shown in FIG. 2 is common to the conventional pendulum-type writing instrument 11 using FIG. 1, and includes a chuck mechanism composed of a main body portion 21, a core tank 23, a pendulum 24, a chuck guide 25, etc., and an eraser 28. The core 31 accommodated in the core tank 23 is fed out from the tip (the left end in FIG. 2(a)).

[0027] Hereinafter, in this specification, the pendulum-type writing instrument 20 may be simply referred to as the writing instrument 20.

[0028] The main body portion 21 is cylindrical, extends in the front-rear direction, and has a taper 22 at the tip.

[0029] The core tank 23 extends in the front-rear direction, is disposed inside the main body portion 21, and houses the core 31 therein.

[0030] The pendulum 24 extends in the front-rear direction and is disposed inside the main body 21, and is movable in the front-rear direction within the main body 21.

[0031] The pendulum 24 can be made of a resin having a predetermined weight with such properties as slidability and durability, like the pendulum 4 employed in the conventional pendulum-type writing instrument 12 illustrated in FIG. 1. In the case of the writing instrument 20 of the present embodiment, as will be described later, engagement is performed between the main body side latching portions (guide ribs 32a, 32b) that extend in the front-rear direction along the inner periphery of the main body 21 and are provided in the main body 21, and the pendulum side engaging portions (guide grooves 33a, 33b) that extend in the front-rear direction along the outer periphery of the pendulum 24 and are provided in the pendulum 24, whereby engagement is performed between the main body 21 and the pendulum 24. As a result, the pendulum 24 is movable in the front-rear direction, but is not movable in the circumferential direction around the central axis of the main body 21. Considering this, the pendulum 24 is configured with a resin having slidability and durability and having a predetermined weight.

[0032] Also, as was also employed in the conventional pendulum-type writing instrument 12 illustrated in FIG. 1, weights 24b for adding weight can be incorporated to form the pendulum 24a (FIG. 5).

[0033] The chuck mechanism disposed on the tip side of the main body 21 inside the main body 21 is the same as the conventional chuck mechanism disposed in the conventional pendulum-type writing instrument, and is constituted by a chuck guide 25 and the like. In FIG. 2, not only the chuck guide 25 but also clutches 26a and a chuck 26b disposed inside the tip side of the main body 21 are illustrated.

[0034] On the chuck guide 25 side within the main body 21, a spring 27 that exhibits the same function as in the case of the conventional pendulum-type writing instrument 12 illustrated in FIG. 1 and that does not have too large a load is disposed.

[0035] In the illustrated embodiment, a core tank 23 that houses a core 11 is installed between a rubber holder 29 that supports a rubber 28 and a chuck guide 25 inside the radial direction of a pendulum 24. The core tank 23 can be fitted to the chuck guide 25 by fitting the front end side of the core tank 23 with the rear end side of the chuck guide 25 or the like. Also, the core tank 23 can be made free to move freely in the front-rear direction.

[0036] The rubber 28 is arranged at the rear end of the main body 21 in a form supported by the rear end side of a rubber holder 29 fitted to the rear end of the main body 21.

[0037] The rubber holder 29 that supports the rubber 28 at the rear end side is fitted to the rear end of the main body 21 so as to be movable in the front-rear direction and movable in the circumferential direction around the central axis of the main body 21.

[0038] When fitting is not performed between the core tank 23 and the chuck guide 25 described above, the core tank 23 and the rubber holder 29 can be made to have a structure in which they are fitted by fitting the rear end side of the core tank 23 with the front end side of the rubber holder 29 or the like.

[0039] As will be described later, the rubber holder 29 moves inside the main body 21 so that the actuating convex portions 35a, 35b provided on the rubber holder 29 move in the front-rear direction and the like inside the actuating guide grooves 50a, 50b formed on the rear end side of the main body 21. Therefore, it is also possible not to perform fitting between the core tank 23 and the rubber holder 29.

[0040] FIG. 8 is a diagram for explaining the state of the pendulum 24 and the eraser holder 29 when using the eraser 28 with the tip side up and the rear end side down in the pendulum-type writing instrument 20 illustrated in FIG. 2. Although FIG. 8(a) shows a cross section with a part of the internal structure omitted, as described above, the pendulum 24 is movable back and forth within the main body 21, and the eraser holder 29 that supports the eraser 28 at the rear end side is movably fitted at the rear end of the main body 21 in the front-rear direction and is also movably fitted circumferentially around the central axis of the main body 21.

[0041] Therefore, as shown in FIG. 8, when the tip side is up and the rear end side is down, the pendulum 24 and the eraser holder 29 move to the rear end side by their own weights. When the core tank 23 is fitted and fixed to the chuck guide 25, as shown in FIG. 8(a), a gap indicated by L1 will open below the rear end of the core tank 23.

[0042] In addition, as described above, when the core tank 23 is free to move freely in the front-rear direction, although not shown in FIG. 8(a), the core tank 23 also moves to the rear end side by its own weight in the same manner as the pendulum 24 and the eraser holder 29.

[0043] The basic configuration and structure of the pendulum-type writing instrument 20 of the present embodiment described above are the same as those of the conventional pendulum-type writing instrument 11 provided with an eraser at the rear end side, so a detailed description will be omitted. Hereinafter, without incorporating a spring with a strong load at the rear end side of the cylindrical main body constituting the writing instrument 20, a characteristic configuration and structural part of the present invention that can prevent a situation where a knocking operation occurs and the core is fed out when using the eraser will be described in detail.

[0044] In the pendulum-type writing instrument 20 of the present embodiment, the main body 21 and the pendulum 24 are engaged, and on this basis, the pendulum 24 is movable back and forth within the main body 21 in the same manner as in the conventional pendulum-type writing instrument.

[0045] In this embodiment, the main body 21 is provided with a main body side latching portion that extends in the front-rear direction along the inner circumference of the main body 21. Further, the pendulum 24 is provided with a pendulum side engaging portion that extends in the front-rear direction along the outer circumference of the pendulum 24. The main body 21 and the pendulum 24 are engaged with each other by the engagement of the main body side latching portion and the pendulum side engaging portion.

[0046] In this embodiment, as shown in FIG. 3, the main body 21 is provided with guide ribs 32a and 32b that extend in the front-rear direction along the inner circumference of the main body 21. In the illustrated embodiment, the guide ribs 32a and 32b correspond to the main body side latching portion that the main body 21 is provided with and that extends in the front-rear direction along the inner circumference of the main body 21.

[0047] Further, in this embodiment, as shown in FIG. 4, the pendulum 24 is provided with guide grooves 33a and 33b that extend in the front-rear direction along the outer circumference of the pendulum 24. In the illustrated embodiment, the guide grooves 33a and 33b correspond to the pendulum side engaging portion that the pendulum 24 is provided with and that extends in the front-rear direction along the outer circumference of the pendulum 24.

[0048] The guide ribs 32a and 32b provided in the main body 21 and the guide grooves 33a and 33b provided in the pendulum 24 are engaged with each other as shown in FIG. 2(d).

[0049] In this embodiment, the cylindrical pendulum 24 having a hollow core tank insertion hole 42 inside is provided with a pendulum rear end portion 40 at the rear end as shown in FIG. 4. Further, the eraser holder 29 is provided with an eraser holder tip portion 34 at the tip as shown in FIG. 6.

[0050] The pendulum 24 and the rubber holder 29 are respectively provided with a pendulum-side latching portion and a rubber-holder-side engaging portion at the rear end portion 40 of the pendulum and the tip 34 of the rubber holder. As shown in FIG. 12(a), when the rear end portion 40 of the pendulum and the tip portion 34 of the rubber holder are in contact with each other and a backward force is applied to the rubber holder 29 with respect to the pendulum 24, when the rubber holder 29 moves in the circumferential direction around the central axis of the main body portion 21, that is, when the rubber holder 29 moves in the direction indicated by the arrow 100 in FIG. 12, the pendulum-side latching portion and the rubber-holder-side engaging portion will engage with each other.

[0051] In the illustrated embodiment, as shown in FIG. 4, the pendulum 24 is provided with locking protrusions 41a and 41b at the rear end portion 40 of the pendulum. In the illustrated embodiment, the locking protrusions 41a and 41b correspond to the pendulum-side latching portion provided by the pendulum 24 at the rear end portion 40 of the pendulum.

[0052] As described above, the pendulum 24 is engaged with the main body portion 21 by the engagement of the guide ribs 32a and 32b (main-body-side latching portions) extending in the front-rear direction and the guide grooves 33a and 33b (pendulum-side engaging portions), and is movable in the front-rear direction, but is not allowed to move in the circumferential direction around the central axis of the main body portion 21. Therefore, the set positions of the pendulum-side latching portions (locking protrusions 41a and 41b) provided by the pendulum 24 in the circumferential direction of the central axis of the main body portion 21 are fixed.

[0053] Also, in the illustrated embodiment, as shown in FIG. 6, the rubber holder 29 is provided with locking recesses 36a and 36b at the tip 34 of the rubber holder. In the illustrated embodiment, the locking recesses 36a and 36b correspond to the rubber-holder-side engaging portion provided by the rubber holder 29 at the tip 34 of the rubber holder.

[0054] The rubber holder 29 shown in FIG. 6 is provided with a slit 37 extending in the front-rear direction on the rear end side of the locking recesses 36a and 36b, continuously to the locking recesses 36a and 36b, as shown in FIG. 6(b).

[0055] When pushing and assembling the eraser holder 29 into the rear end of the main body 21, as shown in Fig. 7, the slit 37 deforms and the tip side of the eraser holder 29 bends. Therefore, in order to facilitate the pushing of the eraser holder 29 into the rear end of the main body 21, as shown in Fig. 6(b), it is advantageous that a slit 37 extending in the front-rear direction is formed continuously with the locking recesses 36a and 36b and on the rear end side of the locking recesses 36a and 36b. Also, in order to facilitate the assembly of the actuating protrusions 35a and 35b provided on the eraser holder 29, which will be described later, into the actuating guide grooves 50a and 50b formed on the rear end side of the main body 21, as shown in Fig. 6(b), it is advantageous that a slit 37 extending in the front-rear direction is formed continuously with the locking recesses 36a and 36b and on the rear end side of the locking recesses 36a and 36b.

[0056] The cylindrical eraser holder 29 shown in Fig. 6 is provided with an eraser fitting rib 29a extending in the front-rear direction on the inner peripheral wall of the rear end side in consideration of the fitting of the eraser 28 from the rear end of the eraser holder 29.

[0057] Fig. 12 is a diagram for explaining the positional relationship between the pendulum 24 and the eraser holder 29 when the eraser 28 is being used in the pendulum type writing instrument 20 shown in Fig. 2. As shown in Fig. 12(a), with the rear end portion 40 of the pendulum and the tip portion 34 of the eraser holder in contact, when the eraser holder 29 moves circumferentially around the central axis of the main body 21, that is, in the direction indicated by the arrow 100 in Fig. 12, the engagement between the locking protrusions 41a and 41b, which are the pendulum side latching portions, and the locking recesses 36a and 36b, which are the eraser holder side engaging portions, is carried out.

[0058] On the rear end side of the main body portion 21, as shown in FIGS. 2(a), (b), 3(a), and 3(b), operation guide grooves 50a and 50b are formed so as to penetrate the main body portion peripheral wall 21a, which is the peripheral wall of the main body portion 21, in the radial direction, inside and outside, on the rear end side of the main body portion 21. The operation guide groove 50a includes a knocking groove portion 51a extending in the front-rear direction and a retracting groove portion 51b that is continuous with the knocking groove portion 51a and extends obliquely from the rear end of the knocking groove portion 51a toward the rear end of the main body portion 21 with respect to the direction in which the knocking groove portion 51a extends. The operation guide groove 50a guides the front-rear movement of the eraser holder 29, which will be described later, and the circumferential movement described above.

[0059] FIG. 2(a) is a front view of the pendulum type writing instrument 20 according to the present embodiment. As shown in FIGS. 2(b) and 3(b), on the back side of the main body portion 21 of the pendulum type writing instrument 20, similarly to that shown in FIG. 2(a), on the rear end side of the main body portion 21, an operation guide groove 50b is formed so as to penetrate the main body portion peripheral wall 21a, which is the peripheral wall of the main body portion 21, in the radial direction, inside and outside. The operation guide groove 50b also includes a knocking groove portion 51c extending in the front-rear direction and a retracting groove portion 51d that is continuous with the knocking groove portion 51c and extends obliquely from the rear end of the knocking groove portion 51c toward the rear end of the main body portion 21 with respect to the direction in which the knocking groove portion 51c extends. The operation guide groove 50b also guides the front-rear movement of the eraser holder 29, which will be described later, and the circumferential movement described above.

[0060] The eraser holder 29 is provided with operation convex portions 35a and 35b symmetrically in diameter on the cylindrical portion on the tip side thereof, as shown in FIG. 6. The operation convex portions 35a and 35b respectively project from the inside to the outside in the radial direction into the operation guide grooves 50a and 50b that are symmetrically formed in diameter on the rear end side of the main body portion 21 as described above (FIGS. 2(a) and 2(c)).

[0061] Thus, as shown in FIGS. 2 and 3, Z-shaped operating guide grooves 50a and 50b are provided on the side surface of the rear end side of the main body 21, and the operating convex portions 35a and 35b of the eraser holder 29 are loosely fitted therein so as to be able to move freely within the operating guide grooves 50a and 50b. In addition, the eraser holder 29 is structured and configured not to come off from the main body 21 by the operating guide grooves 50a and 50b and the operating convex portions 35a and 35b.

[0062] When the writing instrument 20 is turned upside down to use the eraser 28, as shown in FIG. 8(a), the pendulum 24 and the eraser holder 29 move toward the rear end direction as indicated by the arrow 110.

[0063] When the pendulum 24 and the eraser holder 29 move toward the rear end direction as indicated by the arrow 110, the operating convex portions 35a and 35b of the eraser holder 29 move in the direction of the arrow 110 within the knock grooves 51a and 51c of the operating guide grooves 50a and 50b.

[0064] When the operating convex portions 35a and 35b of the eraser holder 29 that have moved in the direction of the arrow 110 within the knock grooves 51a and 51c of the operating guide grooves 50a and 50b reach the rear ends of the knock grooves 51a and 51c, they will subsequently move in the rear end direction within the retraction grooves 51b and 51d.

[0065] The retraction groove 51b extends continuously from the rear end of the knock groove 51a obliquely with respect to the direction in which the knock groove 51a extends toward the rear end of the main body 21, and the retraction groove 51d also extends continuously from the rear end of the knock groove 51c obliquely with respect to the direction in which the knock groove 51c extends toward the rear end of the main body 21.

[0066] Also, as described above, the pendulum 24 is engaged with the main body 21 by the engagement of guide ribs 32a and 32b (main body side latching portions) extending in the front-rear direction and guide grooves 33a and 33b (pendulum side engaging portions). The pendulum 24 is movable in the front-rear direction but cannot move in the circumferential direction around the central axis of the main body 21.

[0067] On the other hand, the eraser holder 29 is movably fitted at the rear end of the main body 21 in the front-rear direction and is also movably fitted in the circumferential direction around the central axis of the main body 21. As shown in Fig. 12(a), with the rear end portion 40 of the pendulum and the tip portion 34 of the eraser holder in contact, the eraser holder 29 can move in the circumferential direction around the central axis of the main body 21.

[0068] Therefore, when the actuating convex portions 35a and 35b of the eraser holder 29 move into the knock grooves 51a and 51c of the actuating guide grooves 50a and 50b formed in the main body 21 in the direction of arrow 110 and reach the rear ends of the knock grooves 51a and 51c, and then the eraser holder 29 continues to move in the direction of arrow 110, as described above, the actuating convex portions 35a and 35b attempt to move in the rear end direction (the direction indicated by arrow 112 (Fig. 9(b))) in the relief grooves 51b and 51d that are continuous with the rear ends of the knock grooves 51a and 51c. For this reason, the eraser holder 29 moves in the main body 21 in the direction of arrow 100, that is, in the circumferential direction (the direction of arrow 100) around the central axis of the main body 21. As a result, the actuating convex portions 35a and 35b of the eraser holder 29 that have moved in the direction of arrow 110 in the knock grooves 51a and 51c of the actuating guide grooves 50a and 50b to reach the rear ends of the knock grooves 41a and 41c will subsequently move in the rear end direction in the relief grooves 51b and 51d as shown by arrow 112 (Fig. 9(b)).

[0069] Here, with the pendulum rear end portion 40 and the eraser holder tip portion 34 in contact, when the eraser holder 29 moves in the circumferential direction around the central axis of the main body portion 21, that is, in the direction indicated by the arrow 100 in FIG. 12, as described above, the locking convex portions 41a and 41b, which are the pendulum side latching portions, and the locking concave portions 36a and 36b, which are the eraser holder side engaging portions, are engaged with each other (FIG. 12(a)).

[0070] When attempting to use the eraser 28 by grounding the eraser 28 on the paper surface 120 (FIG. 10(a)), the eraser 28 is pushed in the tip direction indicated by the arrow 111 together with the supporting eraser holder 29.

[0071] As described above, the locking convex portions 41a and 41b, which are the pendulum side latching portions, and the locking concave portions 36a and 36b, which are the eraser holder side engaging portions, are engaged with each other (FIG. 12(a)). The pendulum 24 is engaged with the main body portion 21 by the engagement of the guide ribs 32a and 32b (main body side latching portions) extending in the front-rear direction and the guide grooves 33a and 33b (pendulum side engaging portions), and is movable in the front-rear direction, but is not movable in the circumferential direction around the central axis of the main body portion 21. Therefore, the eraser holder 29 cannot move in the direction of the arrow 101, that is, cannot rotate.

[0072] As a result, the actuating convex portions 35a and 35b of the eraser holder 29 cannot move in the front end direction, which is the direction indicated by the arrow 113 (FIG. 10(a)), within the retracting groove portions 51b and 51d, and the actuating convex portions 35a and 35b cannot move to the knocking groove portions 51a and 51c.

[0073] Therefore, even when the eraser 28 is grounded on the paper surface and the eraser 28 is used, the eraser holder 29 supporting the eraser 28 does not move in the forward direction indicated by the arrow 111, and the person using the writing instrument 20 can use the eraser 28 with the force they like.

[0074] Also, it is not necessary to provide a spring 10 with a large load on the rear end side as in the conventional pendulum-type writing instrument 12 described with reference to FIG. 1. Compared with the conventional pendulum-type writing instrument 12 having a spring 10 with a large load on the rear end side, the number of parts can be reduced, and cost reduction can be achieved.

[0075] When writing with the writing instrument 20, when the writing instrument 20 is in the state shown in FIGS. 11, the pendulum 24 is engaged with the main body 21 by the engagement of the guide ribs 32a, 32b (main body side latching portions) extending in the front-rear direction and the guide grooves 33a, 33b (pendulum side engaging portions). Although it cannot move in the circumferential direction around the central axis of the main body 21, it can move in the front-rear direction. Therefore, the pendulum 24 moves in the forward direction indicated by the arrow 111 due to its own weight, and the engagement between the locking convex portions 41a, 41b, which are the pendulum side latching portions, and the locking concave portions 36a, 36b, which are the eraser holder side engaging portions, is released.

[0076] As described above, the eraser holder 29 that supports the eraser 28 on the rear end side is fitted to the rear end of the main body 21 so as to be movable in the front-rear direction and movable in the circumferential direction around the central axis of the main body 21. Therefore, when the engagement between the locking convex portions 41a, 41b and the locking concave portions 36a, 36b is released, it can move, that is, rotate, in the direction of the arrow 101.

[0077] As a result, the operating convex portions 35a, 35b of the eraser holder 29 move in the front end direction in the retracting grooves 51b, 51d as shown by the arrow 113 (FIG. 10(a)) and can move into the knocking grooves 51a, 51c.

[0078] When the operating convex portions 35a, 35b of the eraser holder 29 are in the state of moving into the knocking grooves 51a, 51c, when the eraser 28 supported by the eraser holder 29 is pushed in the direction indicated by the arrow 111, that is, when knocked, the operating convex portions 35a, 35b of the eraser holder 29 can move in the knocking grooves 51a, 51c in the forward direction indicated by the arrow 111.

[0079] Therefore, by normally performing a knocking operation or shaking the writing instrument 20 up and down, the pendulum 24 reciprocates between the chuck guide 25 and the eraser holder 29, advancing the chuck guide 25, and the lead 31 can be extended and the writing instrument 20 can be used in the same manner as the conventional general pendulum-type writing instrument 12 illustrated in FIG. 1.

[0080] FIG. 11 is a diagram for explaining the positional relationship between the pendulum 24 and the eraser holder 29 in a state of writing using the pendulum-type writing instrument 20 illustrated in FIG. 2. FIG. 11(a) is a conceptual diagram with a part omitted for explaining a state where the rear end portion 40 of the pendulum and the tip portion 34 of the eraser holder are not in contact. The interval indicated by L2 in FIG. 11(a) is the operating space of the pendulum 24 in the front-rear direction.

[0081] As described above, the embodiments of the present invention have been described with reference to the accompanying drawings. However, the present invention is not limited to the above-described embodiments and can be variously modified within the technical scope grasped from the description of the claims.

[0082] For example, in the above, the guide ribs 32a and 32b, which are ridges extending in the front-rear direction on the inner periphery of the main body portion 21, corresponded to the main body side latching portions extending in the front-rear direction on the inner periphery of the main body portion 21 provided by the main body portion 21. Also, the guide grooves 33a and 33b, which are groove ridges extending in the front-rear direction on the outer periphery of the pendulum 24, corresponded to the pendulum side engaging portions extending in the front-rear direction on the outer periphery of the pendulum 24 provided by the pendulum 24. In contrast, although not shown, a groove ridge extending in the front-rear direction on the inner periphery of the main body portion 21 can correspond to the main body side latching portion extending in the front-rear direction on the inner periphery of the main body portion 21, and a ridge extending in the front-rear direction on the outer periphery of the pendulum 24 can correspond to the pendulum side engaging portion extending in the front-rear direction on the outer periphery of the pendulum 24, in terms of configuration and structure.

[0083] Further, the number of main body side engaging portions formed by ridges or groove ridges extending in the front-rear direction on the inner periphery of the main body portion 21 can be one or a plurality, and accordingly, the number of pendulum side engaging portions formed by groove ridges or ridges extending in the front-rear direction on the outer periphery of the pendulum 24 can be one or a plurality.

[0084] Also, in the above description, the pendulum side engaging portions are the locking convex portions 41a and 41b, and the eraser holder side engaging portions are the locking concave portions 36a and 36b. In contrast, although not shown in the drawings, a locking concave portion can be formed as a pendulum side engaging portion at the pendulum rear end portion 40 of the pendulum 24, and a locking convex portion can be formed as an eraser holder side engaging portion at the eraser holder tip 34 of the eraser holder 29.

[0085] Also, the pendulum side engaging portion and the eraser holder side engaging portion respectively provided at the pendulum rear end portion 40 and the eraser holder tip 34 are engaged with each other when the eraser holder 29 moves in the circumferential direction around the central axis of the main body portion 21 in a state where the pendulum rear end portion 40 and the eraser holder tip portion 34 are in contact with each other and a backward force is applied to the eraser holder 29 from the pendulum 24, that is, when the eraser holder 29 moves in the direction indicated by the arrow 100 in FIG. 12. As a result, since the pendulum 24 cannot move in the circumferential direction, a structure in which the eraser holder 29 cannot move in the circumferential direction and is locked may be adopted. Therefore, a pendulum side engaging portion formed of one convex portion or concave portion can be formed at the pendulum rear end portion 40 of the pendulum 24, and correspondingly, an eraser holder side engaging portion formed of one concave portion or convex portion can be formed at the eraser holder tip 34 of the eraser holder 29.

[0086] Furthermore, at the pendulum rear end portion 40 of the cylindrical pendulum 24, a pendulum side latching portion composed of a plurality of convex portions or concave portions is formed at predetermined intervals in the circumferential direction. Correspondingly, at the tip 34 of the eraser holder 29 of the cylindrical eraser holder 29, an eraser holder side engaging portion composed of a plurality of concave portions or convex portions is formed at predetermined intervals in the circumferential direction. It is also possible to adopt such a configuration.

[0087] Also, in the above-described embodiment, the operation guide grooves 50a and 50b formed on the rear end side of the main body portion 21 are formed at diametrically symmetric positions on the cylindrical peripheral wall of the main body portion 21, and the operation convex portions 35a and 35b provided on the eraser holder 29 are formed at diametrically symmetric positions on the cylindrical peripheral wall of the eraser holder 29, and respectively project from the radially inner side to the outer side into the operation guide grooves 50a and 50b.

[0088] On the other hand, although not shown, the operation guide groove formed on the rear end side of the main body portion 21 is provided as one, and only one operation convex portion that projects from the radially inner side to the outer side with respect to this one operation guide groove and guides the movement of the eraser holder 29 in the front-rear direction and the circumferential direction is formed on the cylindrical peripheral wall of the eraser holder 29. It is also possible to adopt such a configuration.

[0089] Also, a plurality of operation guide grooves may be formed on the rear end side of the main body portion 21 at predetermined intervals in the circumferential direction, and the eraser holder 29 may be configured to include a plurality of operation convex portions at predetermined intervals in the circumferential direction on its cylindrical peripheral wall.

[0090] Furthermore, as shown in FIG. 13, the main body portion 21 is composed of a cylindrical main body 21b extending in the front-rear direction from the rear end to the front end and a cylindrical tail plug 21c mounted inside the rear end of the main body 21b. It is also possible to adopt a structure in which the eraser holder 29 is movably fitted in the front-rear direction and movably fitted in the circumferential direction around the central axis at the rear end of the tail plug 21c.

[0091] In this case, on the tip side of the plug 21c, operation guide grooves 50a and 50b having the same structure as the above-described operation guide grooves 50a and 50b are formed by penetrating the plug peripheral wall, which is the peripheral wall of the plug 21c, in the radial direction inside and outside. The operating convex portions 35a and 35b of the eraser holder 29 project from the inside to the outside in the radial direction of the operation guide grooves 50a and 50b formed by penetrating the plug peripheral wall, which is the peripheral wall of the plug 21c, in the radial direction inside and outside on the tip side of the plug 21c.

Claims

1. A cylindrical main body portion extending in the front-rear direction from the rear end toward the front end, A core tank extending in the front-rear direction and disposed inside the main body portion, A pendulum extending in the front-rear direction and disposed inside the main body portion, being movable in the front-rear direction within the main body portion, A chuck mechanism disposed inside the main body portion on the tip side of the main body portion, An eraser disposed at the rear end of the main body portion and comprising, a pendulum-type writing instrument in which a core accommodated in the core tank is fed out from the tip, The main body portion and the pendulum are engaged by engaging a main body side engaging portion extending in the front-rear direction on the inner periphery of the main body portion provided in the main body portion and a pendulum side engaging portion extending in the front-rear direction on the outer periphery of the pendulum provided in the pendulum, An eraser holder that supports the eraser on the rear end side is fitted to the rear end of the main body portion so as to be movable in the front-rear direction and movable in the circumferential direction around the central axis of the main body portion, The pendulum includes a pendulum rear end portion that abuts on the eraser holder tip portion that is the tip of the eraser holder at the rear end, The pendulum and the eraser holder are provided with a pendulum side engaging portion and an eraser holder side engaging portion that engage with each other when the eraser holder moves in the circumferential direction in a state where the pendulum rear end portion and the eraser holder tip portion are in contact and a backward force is applied from the pendulum to the eraser holder, at the pendulum rear end portion and the eraser holder tip respectively, An operation guide groove for guiding the movement of the eraser holder in the front-rear direction and the circumferential direction is formed by penetrating the main body portion peripheral wall, which is the peripheral wall of the main body portion, in the radial direction inside and outside on the rear end side of the main body portion, The operation guide groove includes a knock groove portion extending in the front-rear direction and, continuously with the knock groove portion, an escape groove portion extending obliquely with respect to the direction in which the knock groove portion extends from the rear end of the knock groove portion toward the rear end of the main body portion, The eraser holder is provided with an operation convex portion that protrudes from the inside to the outside in the radial direction of the operation guide groove Pendulum-type writing instrument.

2. The main body portion consists of a cylindrical main body extending in the front-rear direction from the rear end toward the front end and a cylindrical tail plug attached inside the rear end of the main body, At the rear end of the tail plug, the eraser holder is movably fitted in the front-rear direction and is movably fitted circumferentially around the central axis. The operation guide groove in which the operation convex portion of the eraser holder projects from the inside to the outside in the radial direction is formed by penetrating the tail plug peripheral wall, which is the peripheral wall of the tail plug, in the radial direction inside and outside on the tip side of the tail plug. The pendulum type writing instrument according to claim 1.

Images