mechanical pencil

Abstract

We will provide a mechanical pencil 1 that allows users to use up the lead S for as long as possible, even if there is no more lead S available, thereby improving user satisfaction. [Solution] The mechanical pencil 1 is provided with an outer cylinder 5 held by the user, a chuck 2, a cap 9 that moves the chuck 2 forward relative to the outer cylinder 5 by pressing, a spring 48 that moves the advanced chuck 2 backward, and a stopper member 3 that prevents the lead S that is fed out by the chuck 1 from returning. The chuck 2 is configured such that 2 or more chuck arms 22, each having a front chuck 2 that contacts and separates from the outer circumference of the lead S, are spaced apart in the outer circumference direction of the lead S. The stopper member 3 is positioned in the gap portion on the outer circumference of the lead S where the front chuck 2 of the chuck arm 22 does not contact, and contacts the lead in that gap portion. The front chuck 21 of the front chuck 21 of the chuck arm 22 is positioned to protrude beyond the tip portion 51 of the outer cylinder 5 during the feeding operation.

Description

Technical Field

[0001] This invention relates to a mechanical pencil that ejects a lead by knocking.

Background Art

[0002] Conventionally, there has been proposed a mechanical pencil that holds a lead with a chuck and ejects it, prevents the lead from slipping off and returning with a retaining member at the tip thereof, and guides the lead with a pipe-shaped lead guide at the tip thereof, and the lead is ejected from the tip of the lead guide (see Patent Document 1).

[0003] However, according to this structure, if the lead comes out beyond the chuck, the lead cannot be ejected any further. For this reason, this structure has a problem that the lead becomes wasted by the length of the lead guide and the length of the retaining member.

[0004] In addition, in order to make the length of the wasted lead as short as possible, there has been proposed a method of extruding the shortened lead that has come out of the chuck by ejecting the next new lead, and shortening the unusable portion as much as possible.

[0005] However, even in that case, there are problems that the length of the lead guide portion becomes wasted because the lead falls out, and that it cannot be used up to that point if there is no next new lead.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In view of the above-mentioned problems, this invention aims to provide a mechanical pencil that allows the lead to be used up for as long as possible even without a replacement lead, thereby improving user satisfaction. [Means for solving the problem]

[0008] This invention comprises an outer cylinder held by a user, a chuck, a pressing receiving part that advances the chuck relative to the outer cylinder by pressing, an elastic body that retracts the advanced chuck, and a return-stopping member that prevents the core fed out by the chuck from returning, wherein the chuck has a configuration in which two or more chuck arms, each having a front chuck that contacts and separates from the outer circumference of the core, are arranged at a distance from each other in the outer circumference direction of the core. The return stopper member is positioned in a gap on the outer circumference of the core where the front chuck of the chuck arm does not make contact, and is configured to contact the core in that gap, and the tip of the front chuck of the chuck arm is positioned to protrude beyond the tip of the outer cylinder during the feeding operation. The stopper member is located at the tip of the outer cylinder. It is positioned on the inside and flush with the tip of the outer cylinder. It is characterized by being a mechanical pencil. In one aspect of this invention, the front chuck of the chuck arm is formed in an arc shape on its inner surface that abuts against the outer circumference of the core, and the sum of the inner circumferences of the inner surfaces of the front chucks of all the chuck arms is less than the outer circumference of the core, and the sum of the inner circumferences of the contact surfaces of all the stopper members that contact the outer circumference of the core is equal to or shorter than the sum of the inner circumferences of the inner surfaces of the front chucks of all the chuck arms minus the outer circumference of the core. [Effects of the Invention]

[0009] This invention provides a mechanical pencil that allows the lead to be used up as long as possible, even without a replacement lead, thereby improving user satisfaction. [Brief explanation of the drawing]

[0010] [Figure 1] A partial cross-sectional view showing the structure of a mechanical pencil. [Figure 2] A cross-sectional view showing the structure of a mechanical pencil in its normal state. [Figure 3] A cross-sectional view showing the structure of a mechanical pencil in its extended state. [Figure 4] A magnified diagram of the tip of a mechanical pencil. [Figure 5] A magnified front view diagram of the tip of a mechanical pencil. [Modes for carrying out the invention]

[0011] Hereinafter, one embodiment of this invention will be described with reference to the drawings. [Examples]

[0012] Figure 1 is a partial cross-sectional view showing the configuration of mechanical pencil 1. The mechanical pencil 1 comprises a cylindrical outer cylinder 5 that tapers to a truncated cone shape at the tip (left side in Figure 1, the same applies hereafter), a cylindrical lead tank 7 that stores multiple leads S inside the outer cylinder 5, a chuck 2 fixed to the tip of the lead tank 7, a cylindrical sleeve 8 fixed to the outer circumference of the lead tank 7 and capable of moving forward (left in Figure 1) and backward (right in Figure 1) inside the outer cylinder 5, a spring 48 (elastic body) whose rear end abuts against the tip of the sleeve 8 and biases the sleeve 8 in the backward direction, a support member 4 that supports the front end of the spring 48, and a bottomed cylindrical cap 9 (pressure receiving part) that is fitted inside the rear end of the outer cylinder 5, becomes the cap of the lead tank 7, and abuts against the rear end of the sleeve 8.

[0013] Figures 2 and 3 are cross-sectional views showing the configuration of the mechanical pencil 1, and Figure 4 is an enlarged explanatory view of the tip of the mechanical pencil 1. Figure 2 shows the normal state in which the lead S has not been extended, and Figure 3 shows the extended state in which the cap 9 is pressed and the lead S is extended. Figure 4(A) shows the normal state in which the lead S has not been extended, and Figure 4(B) shows the extended state in which the cap 9 is pressed and the lead S is extended.

[0014] As shown in Fig. 2, the chuck 2 is composed of two chuck arms 22 symmetrically arranged to sandwich the core S. The chuck arms 22 are fixed at the tips of the core tank 7 on the base side (rear end side), and in the released normal state, the tip side is configured to open outward (in the direction away from the core S). When pressed from the outside to the inside, it shrinks inward, but when released, it expands by its elastic force. The inner surface (the surface on the core S side) of the chuck arm 22 is an arc-shaped surface that is flush with the inner surface of the core tank 7.

[0015] A rear chuck 23 is provided at a portion slightly separated from the base of the chuck arm 22. The rear chuck 23 protrudes inward so that the inner surface on the core S side is smaller in diameter than the base side of the chuck arm 22. The rear end surface on the core tank 7 side of this protruding portion functions as a carry-out prevention surface 24a that locks the stored cores S other than the core S being fed out so that they are not fed out, and the space behind this carry-out prevention surface 24a functions as a core accommodation space 24. A tapered surface 23b that increases in diameter toward the tip is provided on the base side of the outer periphery of the rear chuck 23. As shown in Fig. 3, this tapered surface 23b serves to contact the inner surface of the tip 41 of the support member 4 when the chuck arm 22 is retracted backward after the feeding operation, reducing the inner diameter.

[0016] A front chuck 21 is provided at the tip side of the chuck arm 22. The front chuck 21 protrudes inward so that the inner surface on the core S side is slightly smaller in diameter than the base side of the chuck arm 22. A tapered surface 21b that increases in diameter toward the tip is provided on the base side of the outer periphery of the front chuck 21. As shown in Fig. 3, this tapered surface 21b serves to contact the inner surface 51a of the tip portion 51 of the outer cylinder 5 when the chuck arm 22 is retracted backward after the feeding operation, reducing the inner diameter.

[0017] As shown in FIGS. 4(A) and 4(B), the inner surface of the front chuck 21 is formed in an arc shape along the outer circumference of the core S, and functions as a core holding surface 21a that abuts against the core S to hold and feed out the core S. As shown in FIG. 2, the inner surface of the rear chuck 23 functions as a core holding surface 23a that abuts against the core S to hold and feed out the core S, similar to the inner surface of the front chuck 21.

[0018] As shown in FIG. 2, two return prevention members 3 are provided symmetrically on the inner surface of the tip of the tip portion 51 of the outer cylinder 5 with the core S interposed therebetween. As shown in FIG. 4(A), this return prevention member 3 is disposed between the outer circumferential directions of the two front chucks 21 of the chuck 2, and the arc-shaped inner surface functions as a return prevention surface 3a that prevents the core S from slipping off or returning. At least a part or all of the return prevention member 3 on the side of the return prevention surface 3a is made of a material such as rubber that has a high frictional force and elasticity. Thereby, the core S can be held by the return prevention surfaces 3a of the two return prevention members 3, and it is possible to prevent the core S from slipping off during feeding, and to prevent the core S from being pulled back when the chuck 2 returns after the feeding operation.

[0019] The support member 4 is disposed inside the outer cylinder 5 and outside the chuck 2, and is fixed to the outer cylinder 5. The tip 41 of the support member 4 functions as a chuck ring that tightens to a smaller diameter when the fed rear chuck 23 returns. The rear end (base side) of the support member 4 functions as a spring support surface 43 that supports the front end of the spring 48. The shape of the return prevention member 3 is configured to be long in the forward and backward direction (axial direction) in which the core S is fed, and short in the width in the outer circumferential direction of the core S. Thereby, it is possible to secure a width for the front chuck 21 to grip the core S, and to secure a sufficient pressing force and frictional force for holding the core S.

[0020] The outer cylinder 5 is integrally formed with the tip portion 51 having a tapered shape. The outer cylinder 5 can be configured as appropriate, such as making the tip portion 51 a detachable separate member, or dividing it in the center and making it detachable in the center.

[0021] The core tank 7 is a cylindrical shape that is shorter and smaller in diameter than the outer cylinder 5, and the core S is stored in the core storage space 7a formed inside the outer cylinder 5. A chuck 2 is fixed to the tip of this core tank 7, and the combined length of the chuck 2 and the core tank 7 is approximately the same length as the outer cylinder 5. The sleeve 8 is located on the outside of the core tank 7, is cylindrical in shape, and is fixed to the core tank 7. The cap 9 has a bottomed cylindrical shape and functions to cover the rear end of the wick tank 7, preventing the wick S from leaking out.

[0022] Figure 5 is an explanatory diagram illustrating the configuration and operation of the front chuck 21 and the return retaining member 3 from a front view. Figure 5(A) shows the normal state (closed), Figure 5(B) shows the extended state (open), and Figure 5(C) shows the holding state (slightly open) in which the lead S is held.

[0023] As shown in Figure 5(A), the two front chucks 21 and the two retaining members 3 are arranged around the entire inner circumference of the tip 51 of the outer cylinder 5, and are alternately arranged to surround the entire outer circumference of the core S (see Figure 5(C)). The two front chucks 21 are the same size and are arranged symmetrically around the core S. Similarly, the two retaining members 3 are the same size and are arranged symmetrically around the core S.

[0024] As shown in Figure 5(B), the inner circumference length 21c of the core holding surface 21a, which is the inner circumference surface of the front chuck 21, is longer than the inner circumference length 3a of the return prevention surface 3a, which is the inner circumference surface of the return prevention member 3. In this embodiment, it is approximately twice as long. The inner circumference length 21c can be the same as or greater than the inner circumference length 3a, preferably 1.5 times or more, and more preferably twice or more. By making the inner circumference length 21c greater than or equal to the inner circumference length 3a, more than half of the outer circumference of the core S can be firmly held by the front chuck 21. This prevents the core S from protruding through the gap (lateral gap) between the two front chucks 21 when writing letters or drawings on paper with the core S held by the front chuck 21, and prevents the core S from breaking due to protruding. Furthermore, the firm hold provides a good writing experience.

[0025] The sum of the inner circumference lengths 21c of all the front chucks 21 and the inner circumference length 3a of the retaining member 3 is the same as or slightly shorter than the outer circumference length of the core S, and is configured to close to a size slightly smaller than the diameter of the core S in the closed state shown in Figure 5(A). As a result, when the core S is held as shown in Figure 5(C), a small gap (clearance) is created between the front chuck 21 and the retaining member 3, allowing the core S to be held firmly and securely. In addition, the distance between opposing inner circumference lengths 3a of the retaining member 3 is slightly shorter than the diameter of the core S, and the retaining member 3 is made of an elastic material such as rubber, which prevents the core S from slipping or retracting, thereby stabilizing the core S feeding operation.

[0026] With the above configuration, the mechanical pencil 1 can dispense the lead S from the lead tank 7 one by one using the rear chuck 23 and advance it little by little using the front chuck 21. During this advancement, the stopper member 3 holds the lead 3 with appropriate pressure and friction, thereby preventing the lead S from slipping out or retracting.

[0027] The front chuck 21 and the stopper member 3 are positioned at the very tip of the mechanical pencil 1, allowing the lead S to be gripped and extended to the very end, enabling almost all of it to be used. In other words, conventional mechanical pencils had a cylindrical lead guide at the tip, which resulted in wasted lead, and also the problem of not being able to extend the remaining short lead if there was no more lead available. These problems have been resolved, making it possible to extend and hold the lead to the very end for writing. As a result, the large amount of lead S consumed can be used effectively for a longer period than before, reducing waste, contributing to environmental protection, and being economically viable.

[0028] It should be noted that this invention is not limited to the above-described embodiments and can take various forms. For example, instead of a press-type mechanical pencil, a cylindrical weight may be placed inside, and when the outer cylinder is shaken in the direction of flow, the weight will press against the pressing body at the rear end of the chuck, causing the chuck to extend. The same effects and advantages can be obtained in this case as well.

[0029] Furthermore, in the normal state, the front chuck 21 and rear chuck 23 of the chuck 2 are configured such that their outer circumferences on the tip side, rather than the tapered surfaces 21b and 23b, contact the inner surface of the tip of the outer cylinder 5 or the inner surface of the tip of the support member 4. However, it is also possible to configure them so that the tapered surfaces 21b and 23b contact the inner surface of the tip of the outer cylinder 5 or the inner surface of the tip of the support member 4. In this case, the normal state will be one in which the chuck 2 is not fully housed, but the advantage of being able to firmly hold the lead S can be obtained. In this case, if the exposed portion on the tip side of the front chuck 21 is provided with a tapered surface that narrows towards the tip, the tip close to the lead S can be made thinner, which can improve the writing feel.

[0030] Furthermore, although we used two chuck arms 22 and two anti-return members 3, the configuration is not limited to this. It is possible to use two or more such configurations, including three chuck arms 22 and three anti-return members 3, or four chuck arms 22 and four anti-return members 3. In these cases, the same effects can be achieved. [Industrial applicability]

[0031] This can be applied to mechanical pencils with a chuck mechanism for extending the lead. [Explanation of symbols]

[0032] 1... Mechanical pencil, 2... Chuck, 3... Retraction retainer, 4... Support member, 5... Outer cylinder, 7... Lead tank, 7a... Lead storage space, 8... Sleeve, 9... Cap, 21... Front chuck, 21a... Lead holding surface, 21b... Tapered surface, 22... Chuck arm, 23... Rear chuck, 23a... Lead holding surface, 23b... Tapered surface, 24... Lead storage space, 24a... Lead ejection prevention surface, 41... Tip, 43... Spring support surface, 48... Spring, 51... Tip section, 51a... Inner surface, S... Lead

Claims

1. It comprises an outer cylinder held by the user, a chuck, a pressing receiving part that advances the chuck relative to the outer cylinder by pressing, an elastic body that retracts the advanced chuck, and a return-stopping member that prevents the core fed out by the chuck from returning. The chuck has a configuration in which two or more chuck arms, each having a front chuck that contacts and separates from the outer circumference of the core, are arranged at a distance from each other in the direction of the outer circumference of the core. The return-stopping member is positioned in a gap on the outer circumference of the core where the front chuck of the chuck arm does not make contact, and is configured to make contact with the core in that gap. The tip of the front chuck of the chuck arm is positioned to protrude more than the tip of the outer cylinder during the feeding operation. The aforementioned retaining member is positioned inside the tip of the outer cylinder and is flush with the tip of the outer cylinder. Mechanical pencil.

2. The front chuck of the chuck arm is The inner surface is formed in an arc shape that contacts the outer circumference of the core, When the inner circumference lengths of the inner surfaces of the front chucks of all the chuck arms are added together, the sum is less than the outer circumference length of the core. and, The sum of the inner circumference lengths of the contact surfaces where all the aforementioned return-stopping members contact the outer circumference of the core is equal to or shorter than the sum of the inner circumference lengths of the inner surfaces of the front chucks of all the chuck arms, minus the outer circumference length of the core. The mechanical pencil according to claim 1.

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