JP7362127B2 - Mechanical pencil with lead breakage prevention mechanism - Google Patents

Description

The present invention relates to a mechanical pencil with a lead breakage prevention mechanism that covers the outer periphery of the tip of the lead with a slider and moves the slider back as the user writes to prevent the lead from breaking.

A mechanical pencil with a slider attached to the taper at the tip of the main body so that it can move back and forth, the tip of the lead inserted into the slider to prevent the lead from breaking, and the slider moved back as the lead wears out. It is widely known (for example, see Patent Document 1). Mechanical pencils require a breaker (lead holding member) made of an elastic material such as rubber to temporarily hold the lead fed out by the lead feeding mechanism. , a breaker is provided inside the slider as described in Patent Document 1.

A slider equipped with such a breaker retreats into the main body as you write, but at that time, the lead is held in the chuck and does not move, so there is no sliding resistance due to the breaker sliding on the surface of the lead. This often results in the inability to obtain a smooth writing feel. A mechanical pencil has also been proposed in which a holder is provided at the front end of a holding cylinder so that it can move forward and backward, and a breaker is fixed to this holding cylinder (for example, see Patent Document 2). However, in the device described in Patent Document 2, since the holder and breaker are arranged independently, the movement of the holder is unstable, and the tip of the holding cylinder may tilt or bend. Therefore, the straightness of the holder cannot be guaranteed and the core may break.

The present applicant has developed a core breakage prevention mechanism that allows the slider to move backward smoothly without any resistance from the breaker when the core wears out and the slider moves without bending or tilting. He invented a mechanical pencil and filed a patent application 2019-114468.

The invention according to the above application has the following configuration.
``Equipped with a main body housing a lead feeding mechanism, an inner taper having a breaker provided at the tip of the main body to temporarily hold the drawn out lead, and an outer taper provided on the main body surrounding the outer periphery of the inner taper. , the breaker is provided at the inner tip of the inner taper, and the outer taper is provided with a slider that protects the core so as to be movable back and forth, and the slider is capable of slidingly contacting the outer periphery of the breaker when moving. A mechanical pencil with a guide hole that fits into the lead to prevent breakage.
With this configuration, the slider retreats into the main body as you write, but since this slider is not provided with a breaker, the slider moves in the axial direction with almost no resistance, giving you a good writing feel. Furthermore, during this movement, the slider is provided with a guide hole that slidably fits into the outer periphery of the breaker provided inside the inner taper, so the slider moves straight while being guided by the breaker and flexes. It does not tilt or tilt, and can reliably prevent core breakage. Furthermore, if a through hole is formed in the inner taper around the breaker, and a guide piece is provided at the rear end of the slider and inserted into the through hole, the linear movement of the slider is further ensured. According to the invention of the above-mentioned application, the rear part of the slider is guided by the outer periphery of the breaker and moves with almost no resistance, and the linear movement of the rear part of the slider is sufficiently ensured. It is preferable that a mechanism is provided to ensure that.

It is widely known that mechanical pencils have a mechanism that prevents the lead from breaking by installing a thin stainless steel pipe (lead protection pipe) at the tip of the slider through which the lead passes. This pipe protrudes from the tapered tip as the slider moves forward, and the lead is protruded through this pipe to write. According to this mechanical pencil, the outer periphery of the tip of the lead is surrounded by a pipe, which prevents the lead from breaking, but since the slider is equipped with an elastic breaker to temporarily hold the lead, When the pipe and slider move backward, the sliding resistance generated between the taper and the pipe and the frictional resistance generated between the breaker and the lead act on the slider, causing a dragging feeling when writing and making the writing feel heavy. Furthermore, in order to ensure visibility when writing, the tip of the lead is usually used with the tip protruding from the pipe by about 3 to 4 mm, so depending on the angle when writing, the pressure exerted from the writing tip of the lead may be reduced. A force is applied to the pipe in the lateral direction, and the force is applied to the pipe in the direction of curving the pipe using the portion in contact with the tip of the taper as a fulcrum. This force becomes a resistance between the outer surface of the pipe and the tapered tip, and also acts on the front part of the slider through the pipe, so the front part of the slider is pushed to the side, which is the cause of inhibiting the straight movement of the slider. It also becomes. As mentioned above, in conventional sliders, the movement of the rear part is unstable, and if a force is applied in the lateral direction to the front part, the slider cannot move in a straight line, which is one of the causes of core breakage. It also becomes.

Patent No. 6281696 (Paragraph 0008, Figure 3) JP 2017-109351 (Claim 3, paragraphs 0010, 0016, 0020, 0025, FIG. 10, FIG. 11)

The problem to be solved by the present invention is to provide a mechanical pencil that is equipped with a slider having a lead protection pipe at the tip to protect the lead, and in which the slider is moved forward when the lead is fed out and is moved backward as the writing is performed. Mechanical pencil with lead breakage prevention mechanism that allows the slider to move back smoothly without creating resistance from the breaker, and to move in a stable state without the slider bending or tilting the rear or front of the slider. The goal is to provide the following.

According to the present invention, there is provided a main body housing a lead feeding mechanism, a lead holder (inner taper) having a breaker section provided at the tip of the main body for temporarily holding the drawn out lead, and an outer periphery of the lead holder. The breaker part is provided at the inner tip of the core holder, and the taper includes a slider having a core protection pipe that protrudes from the tip of the taper when moved forward. The slider is provided so as to be movable back and forth, and the slider is provided with a guide hole that slidably fits into the outer periphery of the breaker portion when retreating, and the taper is provided with an outer pipe through which the core protection pipe is inserted. A mechanical pencil with a lead breakage prevention mechanism is provided. In the present invention, the direction in which the core is fed out from the taper is referred to as "front" or "tip", and the direction in which the core is stored in the main body is referred to as "rear".

Further, according to the present invention, a through hole is formed on the outer periphery of the breaker portion provided in the core holder, and a guide piece that is inserted into the through hole is provided at the rear end of the slider. The above mechanical pencil with a lead breakage prevention mechanism is provided.

The present invention is constructed as described above, and a known lead feeding mechanism is housed in the main body, and a lead holder having a breaker portion that elastically temporarily holds the drawn out lead is provided at the tip of the main body. The core can be drawn out by a knocking operation as usual. The drawn-out lead then passes through a slider attached to a taper provided on the main body so as to be movable back and forth, and protrudes from a lead protection pipe provided at the tip of the slider, allowing writing while preventing the lead from breaking. The slider retreats into the main body as you write, but since the slider is not provided with a breaker section, the slider moves in the axial direction with almost no resistance, giving you a good writing feel. Furthermore, during this movement, the slider is provided with a guide hole that fits slidably into the outer periphery of the breaker section, so the rear part of the slider moves straight while being guided by the breaker section, and does not bend or tilt. You can move around without any problems.

In addition, if a through hole is formed around the breaker part provided in the lead holder and a guide piece is provided at the rear end of the slider and is inserted into the through hole, the slider will be guided by the guide piece and move straight more reliably. move. In this way, linear movement at the rear of the slider is ensured. Furthermore, the core protection pipe provided at the front of the slider has its outer periphery covered by an outer pipe provided in the taper, and because it protrudes through the outer pipe, a force that bends the lead protection pipe is applied when writing. Even if the slider is dropped, there is no fear that the core protection pipe will bend due to the outer pipe, the inclination of the front part of the slider can be suppressed, and the core protection pipe can be prevented from bending when dropped. As described above, when the slider retreats, the rear part is guided by the outer periphery of the breaker part and the through hole, and the front part is guided by the outer pipe so that it does not tilt, so the slider as a whole moves in a straight line reliably and prevents core breakage. It can be prevented.

FIG. 1 is a sectional view showing an embodiment of the present invention. An enlarged sectional view showing a state in which the core is protruding. An enlarged sectional view of the core in a retracted state. The lead holder is shown, (A) is a plan view, (B) is a sectional view, and (C) is a left side view. The slider is shown, (A) is a plan view, (B) is a front view, (C) is a sectional view, and (D) is a right side view. An explanatory diagram of the tapered tip portion with the core protruding. An explanatory diagram of the taper tip portion in a state where the core is retracted. The writing state is shown; (A) is an explanatory diagram when the lead is protruding, and (B) is an explanatory diagram when the lead is retracted. An explanatory diagram of a writing state of a mechanical pencil having a conventional lead protection pipe.

The drawing shows an embodiment of the present invention, in which a cylindrical main body 1 has a grip portion 2 formed on its front outer periphery, and a taper 4 screwed into a small diameter portion 3 provided at the front end. A core feeding mechanism is housed within the main body 1. Various mechanisms can be adopted as the lead feeding mechanism, but in the embodiment shown in the figure, a known knock-type feeding mechanism is shown. A clutch 8 is provided surrounding the outer periphery of the chuck 7 so as to tighten the chuck 7, and a flange portion of the clutch 8 is biased rearward by a spring 9 in a direction toward the tip of the small diameter portion 3. A clip 10 is provided at the rear of the main body 1, and a knock cap 11 fitted onto an eraser (not shown) projects rearward. A core holder is attached to the inside of the taper 4.

Referring to FIG. 4, the lead holder 12 is formed into a cylindrical shape, and includes a rear tube 14 sandwiched between the small diameter portion 3 of the main body 1 and a stepped portion 13 formed on the inner surface of the taper 4, and a rear tube 14 provided in front of the rear tube 14. The front cylinder 16 has a raised ridge 15 on its outer surface that presses against the inner surface of the taper 4. An inner stepped portion 17 is provided on the inner surface of the rear cylinder portion 14, with which the clutch 8 comes into contact so as to release the fastened chuck 7 when the knock cap 11 of the lead feeding mechanism is knocked.

A cylindrical breaker portion 19 is formed at the inner end of the lead holder 12, inward of the front cylinder 16 in FIG. 4, with a connecting portion 18 interposed therebetween. The breaker portion 19 is formed with a breaker for inserting the drawn-out core and temporarily holding it elastically. The breaker can be configured in various ways as is known, and is formed by separately molding an elastic temporary holding member (not shown) that can temporarily hold the core using an elastic rubber material or an elastic plastic material, and then forming it into a cylindrical shape. However, in the embodiment shown in the figure, a slit 20 is provided in a cylindrical part formed of a plastic material to divide it into elastic parts into which the core can be clamped, and the elastic part The piece elastically temporarily holds the core 6.

A semicircular arc-shaped through hole 21 is formed between the breaker portion 19 formed by the connecting portion 18 and the inner surface of the front cylinder portion 16 of the lead holder 12. 4(B) opens into a space 22 continuously formed in the right rear cylinder.

A slider 23 is provided on the taper 4 so as to be movable back and forth. As shown in FIG. 5, the slider 23 includes a slider body 24 and a core protection pipe 25 made of stainless steel and fixed to the slider body 24. The slider body 24 has an insertion hole 26 through which the core is inserted, and a guide hole 27 having an inner diameter that is slidably fitted into the outer periphery of the breaker portion 19 is formed in the rear portion. The diameter is set to the outer diameter inscribed in the through hole 21 of the core holder 14 . A notch 28 is provided in the wall of the slider main body 24 at a distance that allows the connecting portion 18 to be received, thereby forming two guide pieces 29. The guide pieces 29 are guided by the connecting portion 18 and move into the space. It is possible to enter 22.

The taper 4 has a threaded portion 30 at the rear that is screwed to the small diameter portion 3 of the main body 1, and is large enough to accommodate the core holder 12 and slider 23 inside, and has the core protection pipe at the tip. A tip hole 31 from which 25 protrudes is formed. An outer pipe 32 surrounding the core protection pipe 25 is fixed within the tip hole 31. The outer pipe 32 has a strength capable of suppressing the bending force that acts on the lead protection pipe 25 during writing, and preferably has an inner diameter on which the outer surface of the lead protection pipe 25 slides, and an outer diameter that is small enough not to impede visibility. Although it is made of a thin metal pipe material such as a stainless steel pipe, it can also be formed integrally with the taper 4. Further, the length of the outer pipe 32 is preferably such that when the lead protection pipe 25 is protruded during writing, the tip of the outer pipe is located behind the tip of the lead protection pipe 25.

Referring to FIGS. 6 to 8 and FIG. 9 showing a conventional example, the core protection pipe 25a of the slider 23a of the conventional example is guided by the tip hole 31a of the taper 4a for a guide length A1, and protrudes from the tip hole. The base of the core protection pipe 25a is A, and the length from the base A to the tip of the core protection pipe 25a is B1. Further, in FIGS. 6 and 7 showing the embodiment of the present invention, the guide length by which the core protection pipe 25 is guided between the inner end and the tip of the outer pipe 32 is A2, and the guide length from the tip hole 31 of the taper 4 to the outer pipe 32 is The protruding length is D, the tip of the outer pipe 32 is a fulcrum B, the length that the core protection pipe 25 protrudes from this fulcrum B is B2, and the length that the core protection pipe 25 protrudes from the taper 4 is C, as follows. explain.

First, if the protrusion length B1 of the lead protection pipe 25a of a conventional mechanical pencil and the length C of the lead protection pipe 25 of the present invention protruding from the taper 4 are the same length, then in the present invention, from the tip of the outer pipe 32 The length B2 of the protruding core protection pipe is shorter than the length B1. When writing pressure is applied during writing, in the conventional case, as shown in FIG. 9, the load related to the fulcrum A is considered to be B1×load. On the other hand, in the present invention, as shown in FIG. 8, the load related to the fulcrum B is B2×load. Therefore, when the load is the same, since the length of B2 is shorter than the length of B1, it is thought that the load on fulcrum B is less than that on fulcrum A, and in the present invention, the bending force acting on the core protection pipe 25 is As a result, the frictional resistance during retreat is reduced, and the force that presses the front part of the slider laterally is reduced, ensuring linear movement of the slider.

Moreover, when comparing the length of guiding the core protection pipe 25, in the present invention, the core protection pipe 25 is guided by the outer pipe 32 compared to the guide length A1 in which the core protection pipe 25a is guided by the taper 4a in the conventional case. The guide length A2 becomes longer. Therefore, since the core protection pipe 25 can be guided for a long time, the wobbling of the core protection pipe 25, that is, the front part of the slider 23 is reduced, and the slider 23 can be stably moved in the axial direction. Furthermore, the protruding length D of the outer pipe 32 is set to a length that allows writing while ensuring visibility, and by making the inner and outer diameters close to the outer diameter of the lead protection pipe 25, it does not interfere with visibility. Since the lead protection pipe 25 can be protected from bending when the mechanical pencil is dropped, it is possible to eliminate the situation where the lead protection pipe is damaged and writing becomes impossible.

With the above configuration, when the lead is fed out by the lead feeding mechanism, the slider 23 moves forward, and the lead protection pipe 25 passes through the outer pipe 32 and protrudes from the tip of the taper 4, allowing writing.
Furthermore, although the slider 23 moves backward as you write, since the outer periphery of the lead protection pipe 25 is surrounded by the outer pipe 32, the lead protection pipe 25, that is, the front part of the slider 23, reliably moves straight, and at the same time, the slider 23 moves forward. The rear part fits into the outer periphery of the breaker part 19 and retreats while slidingly contacting the inner surface of the through hole 21, and the guide piece 27 moves while being guided by the inner surface of the lead holder 12, so that the rear part of the slider 23 moves in a straight line. This ensures that the slider as a whole does not bend or wobble, and can reliably prevent core breakage.

1 Main body 4 Taper 6 Core 12 Core holder 19 Breaker section 21 Through hole 23 Slider 25 Core protection pipe 27 Guide hole 29 Guide piece 32 Outer pipe

Claims (2)

The main body houses the lead feeding mechanism,
a lead holder having a breaker part provided at the tip of the main body and temporarily holding the drawn-out lead;
a taper provided at the front of the main body surrounding the outer periphery of the core holder;
The breaker section is provided at the inner tip of the lead holder,
The taper is provided with a slider that can be moved back and forth and has a core protection pipe that protrudes from the tip of the taper when the taper moves forward;
The slider is provided with a guide hole that is slidably fitted into the outer periphery of the breaker portion when the slider is retracted;
The taper is provided with an outer pipe through which the core protection pipe is inserted.
When the slider moves forward and the core protection pipe is guided by the outer pipe and protrudes from the tip of the taper, the length of the core protection pipe extending from the tip of the taper is A mechanical pencil with a lead breakage prevention mechanism whose outer pipe is longer than the length extending from the tip of the taper mentioned above. Claim 1: The breaker part provided in the lead holder is formed into a cylindrical shape, and a through hole is provided on the outer periphery of the breaker part, and a guide piece is provided at the rear end of the slider to be inserted into the through hole. Mechanical pencil with lead breakage prevention mechanism described in .

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