JP7461826B2 - Knock-type writing instrument - Google Patents

Description

The present invention relates to a knock-type writing instrument.

There are known so-called knock-type writing instruments that have an operating part equipped with a knock member at the rear end of the barrel, and that switch between a writing state in which the writing part (the pen tip) protrudes from the tip of the barrel and a non-writing state in which the writing part is retracted into the barrel by performing a knock operation that presses the operating part forward against the biasing force of a spring arranged inside the barrel (see, for example, Patent Document 1). In a knock-type writing instrument, the knock operation causes the knock member to move forward together with the rotor, causing the rotor to rotate. The knock-type writing instrument can be switched between a writing state and a non-writing state in response to the rotation of the rotor caused by the knock operation.

JP 2018-149787 A

In the knock-type writing instrument described in Patent Document 1, the rear part of the rotor is inserted into the inside of a cylindrical knock member, and the knock member and the rotor are fitted together. That is, a convex part is formed on the inner peripheral surface of the knock member, and a concave part is formed on the outer peripheral surface of the rotor, so that the convex part of the knock member and the concave part of the rotor are fitted together. By fitting the knock member and the rotor together, it is possible to prevent the rotor from falling off the barrel, for example, when replacing the refill.

In the knock-type writing instrument described in Patent Document 1, both the protrusion of the knock member and the recess of the rotor are formed in an annular shape, so that during assembly, the rear part of the rotor must be pressed into the inside of the knock member with a strong force. As a result, parts such as the protrusion of the knock member may be damaged.

The present invention aims to provide a knock-type writing instrument that is configured so that the rear part of the rotor can be easily inserted into the knock member during assembly, and the rotor is unlikely to fall off the knock member after assembly.

According to one aspect of the present invention, a knock-type writing instrument is provided that includes a cylindrical knock member and a rotor disposed in front of the knock member and having an insertion portion configured to be insertable into the knock member, the rotor being characterized in that an engaging portion having a non-circular cross-sectional shape is provided on the outer surface of the insertion portion of the rotor, and an engaged portion configured to engage with the engaging portion is provided on the inner peripheral surface of the knock member.

At least a portion of the locking portion may protrude outward from the outer surface of the insertion portion relative to the central axis. The cross-sectional shape of the locking portion may be a shape defined by two arcs and two line segments. The two line segments may be parallel to each other. The locked portion may be an annular protrusion provided on the inner peripheral surface of the knock member.

The aspects of the present invention have the common effect of providing a knock-type writing instrument that is configured so that the rear part of the rotor can be easily inserted into the knock member during assembly, and the rotor is unlikely to fall off the knock member after assembly.

FIG. 1 is a vertical cross-sectional view of a knock-type writing instrument according to an embodiment of the present invention. FIG. 2 is a vertical cross-sectional view of the rear end portion of the knock-type writing instrument. FIG. 3 is a perspective view of the rotor. FIG. 4 is a top view of the rotor. FIG. 5 is a projection of the locking portion of the rotor in the assembly direction. FIG. 6 is a vertical cross-sectional view showing the assembly of the knock member and the rotor.

The following describes in detail an embodiment of the present invention with reference to the drawings. Corresponding components are designated by the same reference symbols throughout the drawings.

Figure 1 is a vertical cross-sectional view of a knock-type writing instrument 1 according to an embodiment of the present invention, and Figure 2 is a vertical cross-sectional view of the rear end of the knock-type writing instrument 1.

The knock-type writing instrument 1 has a barrel 4 formed in a cylindrical shape and equipped with a front shaft 2 and a rear shaft 3, a refill 6 which is a writing body disposed within the barrel 4 and equipped with a writing part 5 at one end, a spring 7 which biases the refill 6 rearward, and a knock mechanism 10 disposed at the rear end of the barrel 4. The knock mechanism 10 has an outer cam 20 (Fig. 2), a cylindrical knock member 30, a rotor 40, and a cover member 50 equipped with a clip 51. In this specification, in the axial direction of the knock-type writing instrument 1, the side of the writing part 5 is defined as the "front" side, and the side opposite the writing part 5 is defined as the "rear" side.

2 in particular, on the inner surface of the rear end of the barrel 4, i.e., the rear axle 3, four protruding outer cams 20 constituting part of the knock mechanism 10 are provided at equal intervals along the circumferential direction. Four guide grooves 21 extending in the front-rear direction are defined by adjacent outer cams 20. The rear end surface of the outer cam 20 constitutes an abutment surface 22 against which the front end surface of the cover member 50 can abut. Eight locking protrusions 31 are provided at equal intervals in the circumferential direction on the outer peripheral surface of the front side of the knock member 30. Each of the locking protrusions 31 is disposed in the guide groove 21 between the adjacent outer cams 20. In addition, each of the locking protrusions 31 is configured to move in the front-rear direction within the guide groove 21 by the knock operation. A cam surface 32 is formed on the front end surface of the knock member 30. A locked portion 33 corresponding to the locking portion 45 of the rotor 40 described later is formed on the inner peripheral surface separated from the opening at the front end of the knock member 30. In this embodiment, the locked portion 33 is a continuous annular protrusion. A cover member 50 is integrally fitted onto the outer peripheral surface of the rear end of the knock member 30.

Figure 3 is a perspective view of the rotor 40, Figure 4 is a top view of the rotor 40, i.e., a view of the rotor in the axial direction from the insertion portion 41 side, and Figure 5 is a projection of the locking portion 45 of the rotor 40 in the assembly direction. Specifically, in Figure 5, Figure 5(A) is a projection of the locking portion 45 in a direction along the central axis of the rotor 40, and Figure 5(B) is a projection of the locking portion 45 in a direction inclined from the central axis of the rotor 40.

The rotor 40 is composed of a cylindrically formed insertion portion 41 that is inserted into the inside of the knock member 30 from the front end portion and used for centering, and a cylindrically formed cam portion 42 that is disposed in front of the insertion portion 41. The cam portion 42 has a larger outer diameter than the insertion portion 41. The rear end surface of the cam portion 42 is formed with a cam receiving surface 43 that cooperates with the cam surface 32 of the knock member 30 and has a complementary shape. The outer peripheral surface of the cam portion 42 is provided with four inner cams 44 that are protrusions extending in the front-rear direction and are equally spaced in the circumferential direction. In the knock-type writing instrument 1 in the non-writing state as shown in FIG. 1, each of the inner cams 44 is disposed in the guide groove 21 of the outer cam 20.

A locking portion 45 is formed at the tip of the insertion portion 41. The locking portion 45 may be formed away from the tip of the insertion portion 41. In this embodiment, at least a part of the locking portion 45 is a protrusion formed so as to protrude outward from the outer surface of the insertion portion 41 with respect to the central axis of the insertion portion 41. A tapered surface 46 that tapers toward the rear is formed at the locking portion 45. In addition, two flat surfaces 47 that are parallel to the central axis of the rotor 40 and parallel to each other are formed at the locking portion 45. Since the rotor 40 is molded using at least two molds that open in a direction away from the central axis, a parting line PL extending parallel to the central axis is formed at the center of each of the flat surfaces 47.

As shown in FIG. 5(A), the projected shape of the locking portion 45 in the direction along the central axis, or the maximum cross-sectional shape of the locking portion 45, is a shape defined by two arcs 48 that are part of a circle with a diameter larger than that of the insertion portion 41, and two line segments that are equidistant from the center of the circle and are formed by two flat surfaces 47. Here, the maximum cross-sectional shape of the locking portion 45 is the shape in a plane that passes through the most protruding point from the outer surface of the insertion portion 41 and is perpendicular to the central axis of the insertion portion 41. In FIG. 5(A), the maximum width in the direction parallel to the flat surfaces 47 is the maximum width X1 of the locking portion 45. On the other hand, the width in the direction perpendicular to the flat surfaces 47, i.e., the distance between the flat surfaces 47, is the minimum width Y of the locking portion 45.

In this embodiment, the distance between the two flat surfaces 47, i.e., the minimum width Y, is equal to the outer diameter of the insertion portion 41. Therefore, the center of the flat surface 47 is not formed so as to protrude outward from the outer surface of the insertion portion 41 to the central axis of the insertion portion 41, but the other parts, particularly the part of the locking portion 45 corresponding to the arc 48, are formed so as to protrude outward. The locking portion 45 may be configured so that the minimum width Y is greater than the outer diameter of the insertion portion 41.

1 and 2, the knock operation by the knock mechanism 10 will be briefly described. The knock mechanism 10 is biased backward together with the refill 6 by the spring 7. The knock operation is performed by pressing the knock member 30 forward via the cover member 50 to move it forward to a predetermined position. As the knock member 30 moves due to the knock operation, the rotor 40 is pressed and moves forward inside the barrel 4, i.e., inside the rear barrel 3. The predetermined position is a position where the inner cam 44 of the rotor 40 exceeds the guide groove 21 of the outer cam 20. When the force applied to the knock member 30 is released after the knock member 30 has been moved to the above-mentioned predetermined position, the rear end surface of the inner cam 44 of the rotor 40 and the front end surface of the outer cam 20 of the rear barrel 3 are engaged, and the knock-type writing instrument 1 maintains the writing state. When the knocking member 30 is pressed forward again by a knocking operation while the knocking writing instrument 1 is in the writing state, the rear end surface of the inner cam 44 of the rotor 40 and the front end surface of the outer cam 20 of the rear shaft 3 are disengaged. As a result, the knocking mechanism 10 moves backward due to the biasing force of the spring 7, and the knocking writing instrument 1 returns to the non-writing state (Figure 1).

Figure 6 is a vertical cross-sectional view showing the assembly of the knock member 30 and the rotor 40. In particular, the rotor 40 in Figure 6 is shown by a cross-sectional view in which the locking portion 45 has the maximum width X1, that is, a cross-sectional view taken along line S-S in Figure 4. Line S-S is a line passing through the central axis of the rotor 40, and is therefore disposed equidistantly from each of the flat surfaces 47. In the assembly process of the knock type writing instrument 1, the knock member 30 and the rotor 40 are assembled before being placed in the barrel 4. Figure 6 (A) shows the knock member 30 and the rotor 40 during assembly, and Figure 6 (B) shows the knock member 30 and the rotor 40 after assembly. The knock type writing instrument 1 is assembled by placing the knock member 30 and the rotor 40 in the barrel 4 in the state shown in Figure 6 (B).

The assembly of the knock member 30 and the rotor 40 is completed by inserting the insertion portion 41 of the rotor 40 into the inside of the knock member 30 and fitting the knock member 30 and the rotor 40 so that the rotor 40 does not fall off from the knock member 30. Specifically, the fitting of the knock member 30 and the rotor 40 is performed by engaging the locking portion 45 of the rotor 40 with the locked portion 33 of the knock member 30. Therefore, the locked portion 33, which is an annular protrusion on the inner peripheral surface of the knock member 30, is formed so that the effective width of the passage in the knock member 30 defined thereby is smaller than the maximum width X1. The effective width of the passage in the knock member 30 is equal to the diameter of an inscribed circle that touches the apex of the locked portion 33 on a plane perpendicular to the central axis, for example.

During assembly, the insertion portion 41 of the rotor 40 must be inserted into the knock member 30 until the locking portion 45 of the inserted rotor 40 overcomes the locked portion 33 of the knock member 30. If the rotor 40 is pushed hard into the knock member 30 with the central axes of the knock member 30 and the rotor 40 aligned, the locked portion 33 of the knock member 30 or the locking portion 45 of the rotor 40 may be damaged. Therefore, by assembling the rotor 40 while tilting it relative to the central axis of the knock member 30, damage to the locking portion 45, etc. can be prevented.

Specifically, first, as shown in FIG. 6(A), the rotor 40 is tilted in the direction along the line S-S shown in FIG. 4, and the insertion portion 41 of the rotor 40 is inserted into the knock member 30. Here, if the direction along the central axis of the knock member 30 is the assembly direction V, then the projection of the locking portion 45 in the assembly direction V is as shown in FIG. 5(B). Note that the state shown in FIG. 5(A), in which the central axis of the rotor 40 coincides with the assembly direction V, is the state in which the area of the projected shape is maximum. As a result of the tilt of the locking portion 45, the maximum width in the projection becomes X2, which is smaller than X1. On the other hand, the minimum width Y in the direction perpendicular to the tilt direction does not change.

As a result, the locking portion 45 of the rotor 40 can climb over the locked portion 33 of the knock member 30 while minimizing interference between the locking portion 45 and the locked portion 33, and the knock member 30 and the rotor 40 can be easily assembled (FIG. 6(B)). Furthermore, the tapered surface 46 of the locking portion 45 abuts against the locked portion 33 to guide the insertion of the rotor 40, allowing the locking portion 45 to climb over the locked portion 33 more smoothly.

Referring again to FIG. 2, in the knock-type writing instrument 1 shown in FIG. 2, the refill 6 is not arranged, and therefore the rotor 40 is not supported from below. Instead, the rotor 40 is prevented from falling off by the locking portion 45 locking with the locked portion 33 of the knock member 30. Furthermore, when the knock-type writing instrument 1 is in an assembled state, the knock member 30 and the rotor 40 are arranged in the barrel 4. Therefore, the movement of the rotor 40 to an inclined position as shown in FIG. 6(A), for example, is restricted by the inner peripheral surface of the barrel 4. Therefore, a state in which the lock between the knock member 30 and the rotor 40 is released, that is, a state in which the projection of the locking portion 45 in the assembly direction V is as shown in FIG. 5(B), is prevented.

As described above, according to an embodiment of the present invention, it is possible to provide a knock-type writing instrument 1 in which the rear portion of the rotor 40 can be easily inserted into the knock member 30 during assembly, and in which the rotor 40 is unlikely to fall off the knock member 30 after assembly.

In the above embodiment, the locking portion 45 of the rotor 40 is a shape defined by two arcs and two line segments, but it may be configured in any way as long as it has a noncircular cross-sectional shape. The locking portion 45 of the rotor 40 is preferably a line-symmetrical shape. Therefore, the locking portion may be, for example, elliptical or rectangular. When the locking portion is elliptical, the locked portion is formed to have an effective width of the passage in the knock member that is greater than the length of the minor axis and smaller than the length of the major axis. Similarly, when the locking portion is rectangular, the locked portion is formed to have an effective width of the passage in the knock member that is greater than the length of the minor axis and smaller than the length of the major axis.

The engaging portion may be configured as desired, so long as it has an effective width of the passage in the knock member that is greater than the minimum width of the engaging portion and less than the maximum width. Thus, in the above-described embodiment, the engaging portion 33 is a continuous annular protrusion, but it may also be a plurality of protrusions spaced apart along the circumferential direction.

In the above-described embodiment, the parting line PL is formed on the flat surface 47 of the locking portion 45. In other words, the mold is designed so that the parting line PL is formed on the flat surface 47. Therefore, strictly speaking, the minimum width Y of the locking portion 45 in FIG. 5 is longer by the height of the protrusion due to the parting line PL. However, the effect on the insertion of the insertion portion 41 of the rotor 40 can be more suppressed by making the minimum width Y longer than by making the maximum width X1 longer so that the parting line PL is formed on the arc 48 portion.

In the above-described embodiment, the knock-type writing instrument 1 is a type in which the operating part provided at the rear end of the barrel 4 is operated by knocking, but it may be a type in which the operating part is provided on the side of the barrel. In addition, in the above-described embodiment, the fitting of the knock member 30 and the rotor 40 is described, but it is not limited to this fitting, and for example, the fitting of the knock member 30 and the cover member 50 may be configured in a similar manner.

The refill 6 may be a ballpoint pen or other type of writing instrument such as a marking pen, a touch pen, or an eraser. In addition, a part or all of the knock member 30 or the cover member 50 may be an erasing section that erases handwriting made with a knock-type writing instrument.

The refill 6 may be a ballpoint pen containing thermochromic ink. Here, thermochromic ink refers to ink that maintains a certain color (first color) at room temperature (e.g., 25°C), changes to another color (second color) when heated to a certain temperature (e.g., 60°C), and then returns to the original color (first color) when cooled to a certain temperature (e.g., -5°C). In a thermochromic writing instrument using thermochromic ink, the second color is made colorless, and the term "erasing" refers to heating a line drawn in the first color (e.g., red) to make it colorless. Therefore, the friction member, which is the erasing part, rubs against the writing surface on which the line was drawn to generate frictional heat, which changes the drawn line to colorless, that is, erases it. Of course, the second color may be a color other than colorless.

REFERENCE SIGNS LIST 1 Knock-type writing implement 2 Front barrel 3 Rear barrel 4 Barrel 10 Knock mechanism 20 Outer cam 21 Guide groove 22 Contact surface 30 Knock member 31 Locking protrusion 32 Cam surface 33 Locked portion 40 Rotor 41 Insertion portion 42 Cam portion 43 Cam receiving surface 44 Inner cam 45 Locking portion 46 Tapered surface 47 Flat surface 48 Arc 50 Cover member 51 Clip

Claims (5)

A knock-type writing instrument including a cylindrical knock member and a rotor disposed in front of the knock member and having an insertion portion configured to be insertable into the knock member,
a locking portion having a non-circular cross-sectional shape is provided on an outer surface of the insertion portion of the rotor,
an engaged portion configured to engage with the engaging portion is provided on an inner circumferential surface of the knock member ,
A knock-type writing instrument characterized in that the locking portion is configured to climb over the locked portion by assembling the rotor while tilting it with respect to the central axis of the knock member . The knock-type writing instrument according to claim 1, wherein at least a portion of the locking portion protrudes outward from the outer surface of the insertion portion relative to the central axis. The knock-type writing instrument according to claim 1 or 2, wherein the cross-sectional shape of the engaging portion is defined by two arcs and two line segments. The knock-type writing instrument according to claim 3, wherein the two line segments are parallel to each other. The knock-type writing instrument according to any one of claims 1 to 4, wherein the engaging portion is an annular protrusion provided on the inner peripheral surface of the knock member.

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