JP2017140716A - Multiple writing implement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multiple writing implement having a mixed group of writing cores with different diameters, which can avoid providing different operational feelings depending on the writing core and has less discomfort in use.SOLUTION: A multiple writing implement comprises: a barrel 2 having a projection port 9 at its tip; a plurality of writing cores 3a, 3b having writing parts 20, 31; a plurality of coil springs 7, 8; and a plurality of operational means 5, 45. The plurality of writing cores 3a, 3b are arranged in the barrel 2 with the coil springs 7, 8 attached to outer peripheral parts of writing cores 20, 31. The plurality of writing cores 3a, 3b are energized toward an inner direction of the barrel 2 by the coil springs 7, 8. Thereby, an operation of operational means 5, 45 can selectively project the writing cores 3a, 3b from the projection port 9 in the multiple writing implement 1, in which the coil springs 7, 8 have respective spring constants substantially equal to each other and have different bore diameters. Some writing cores in a group of the writing cores 3a, 3b have different diameters from other ones. The writing core 3b having a small diameter is provided with a coil springs 8 having a small bore diameter.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a compound writing instrument provided with a mechanism in which a plurality of writing cores move in and out of a shaft cylinder.

  2. Description of the Related Art There is known a compound writing instrument in which a plurality of writing cores including a ball pen refill and a mechanical pencil unit are built in a shaft cylinder. In the compound writing instrument, an operation member such as an operation piece protrudes from the side surface or the rear end of the shaft tube, and the user can operate the operation piece or the like to move each writing core back and forth. The compound writing instrument is used by a user operating an operation piece or the like so that the tip portion of each writing core is selectively projected and retracted from the tip opening of the shaft tube.

  As such a writing instrument, for example, there is a double-type writing instrument disclosed in Patent Document 1. In the dual-type writing instrument disclosed in Patent Document 1, each writing shaft (writing core) is urged rearward by the urging force of the coil spring and is housed in the shaft cylinder, and the operation member such as an operation piece is operated. When one writing shaft selected against the urging force of the coil spring is moved forward, the tip of the writing shaft projects from the tip opening of the shaft tube. And the position of the said writing shaft with respect to a shaft cylinder is fixed by the fixing means, the state which the front-end | tip part protruded will be maintained, and it will be in a writable state.

As described above, the compound writing instrument has a plurality of writing cores, and is used by manually operating an operation piece or the like to selectively project one writing core.
It is desirable that the dual writing instrument has the same operational feeling as the operation piece even if the writing core to be projected is different. For example, if you have four types of writing cores, red ballpoint pen refill, blue ballpoint pen refill, black ballpoint pen refill, and mechanical pencil unit, even if you operate the operation piece etc. It is desirable to be able to.
For this reason, in the conventional double-type writing instrument, springs of the same standard are used as coil springs for urging each writing core backward. That is, in the prior art compound writing instrument, it has a plurality of writing cores, and coil springs are attached to each writing core, but all the coil springs are of the same standard, their natural length (full length), outer diameter, The inner diameter, wire diameter, number of turns, and spring constant were all the same.

JP2011-240555A

  As described above, the dual-type writing instrument incorporates a plurality of writing cores, but the thickness of the writing core is not always uniform. For example, when a ballpoint pen refill and a mechanical pencil unit are mixed, the thickness of the ballpoint pen refill may be different from the thickness of the mechanical pencil unit. Even the ballpoint pen refills may have different thicknesses depending on the color.

  In the prior art, coil springs of the same standard are mounted so that there is no difference in operation feeling even if the thickness of the writing core is different. Therefore, the clearance between the outer peripheral surface of the writing core and the inner periphery of the coil spring differs depending on the writing core, and the operation feeling of the operation piece may be different depending on the writing core. That is, when the clearance is large, the compressed coil spring may be deformed in a meandering manner, or the adjacent coil springs may come into contact with each other, which may make the operation piece feel uncomfortable.

Specifically, it is as follows.
FIG. 12A shows the inside of the dual-type writing instrument, and is a model diagram showing a partially enlarged view of two adjacent writing cores 63a. Coil springs 68 of the same standard are attached to both writing cores 63a. In FIG. 12A, the lower side is the pen tip, and when the writing core 63a is moved to the pen tip side, the coil spring 68 is compressed. That is, when the pen tip of the writing core 63 a is protruded from a tip opening (not shown), the user operates the operation piece 65 against the urging force of the coil spring 68.

  When the left coil spring 68 shown in FIG. 12 (a) is compressed as shown in FIG. 12 (b), the coil spring 68 does not become a meandering shape or the meandering shape becomes small. A distance (clearance) from the inner periphery of the coil spring 68 to the outer peripheral surface of the writing core 63a is set.

Further, an interval F (FIG. 12A) between adjacent writing cores 63 a is set so that the coil spring 68 attached to the writing core 63 a does not come into contact with another adjacent coil spring 68. As a result of the interval F being set, the interval between the coil springs 68 is S4.
When the coil spring 68 is compressed, in the example shown in FIG. 12B, the interval between the compressed coil spring 68 and the closest coil spring 68 adjacent to the coil spring 68 is S5. It becomes. That is, even if the coil spring 68 is buckled, at least the distance S5 (S5 <S4) is secured between the two coil springs 68, and the two coil springs 68 do not contact each other.

However, when the coil spring 68 is mounted on a writing core 63b having a smaller diameter than the writing core 63a as shown in FIG. 13A, the clearance between the coil spring 68 and the writing core 63b is increased. As a result, the coil spring 68 attached to the writing core 63b is likely to have a meandering shape as shown in FIG. 13C when compressed.
That is, as shown in FIG. 13 (a), when a writing core 63b having a relatively small thickness is used, the clearance between the writing core 63b and the coil spring 68 is such that the writing core 63a and the coil spring 68 have a clearance. Therefore, when the coil spring 68 attached to the writing core 63b is compressed, the coil spring 68 tends to exhibit a so-called meandering shape that is eccentric not only in one direction but also in a plurality of directions.
As a result, when the user presses the operation piece 65, there is a concern that the load applied to the hand changes irregularly.

Further, since the clearance between the writing core 63b and the coil spring 68 is large, there is a possibility that when the coil spring 68 is compressed, it contacts with another adjacent coil spring 68. That is, since the clearance is large, the coil spring 68 attached to the writing core 63b may buckle greatly as shown in FIG. 13B. Therefore, the coil spring 68 may come into contact with another adjacent coil spring 68.
As a result, when the operation piece 65 is operated, a feeling of catching occurs.

  As described above, in the conventional writing instrument, the operation feeling of the operation piece or the like may differ depending on the writing core, and the user may feel uncomfortable.

  The present invention focuses on the above-mentioned problems of the prior art, and provides a dual-type writing instrument in which writing cores having different thicknesses are mixed, and the operational feeling does not differ depending on the writing core, and there is little discomfort during use. This is the issue.

  The invention according to claim 1 for solving the above-mentioned problem is a shaft cylinder having an open end and having a hollow portion therein, a plurality of writing cores having a writing portion at the tip, a plurality of coil springs, and a plurality of coil springs. The plurality of writing cores are arranged in the shaft cylinder in a state in which the coil springs are mounted on the outer peripheral portion of each writing core, and each writing core is arranged in the direction of the shaft cylinder by the coil spring. In the dual writing instrument in which the writing core is selectively protruded from the opening at the tip by operating the operating means, the plurality of coil springs have substantially the same spring constant and an inner diameter. Or, there are those having different outer diameters, the writing cores having different thicknesses are mixed, and the thin writing core is provided with a coil spring having a small inner diameter or outer diameter. This is a dual writing instrument.

Here, “substantially the same” means that the same range can be said in consideration of the error of the coil spring. That is, it is difficult to manufacture exactly the same coil spring, and even if manufactured with the same specifications, the same manufacturing method, and the same manufacturing process, the spring constant will vary to some extent depending on the lot. Therefore, for example, JIS B 2704-2: 2009 “Part 2: How to express the specifications of compression coil springs 6.2 (c) Tolerance of spring constants Table 4” defines allowable values of spring constants. Yes. For example, JIS B 2704-2: 2009 allows an error of plus or minus 12% at the maximum.
In the present invention, the range of “substantially the same” is not limited to the above-mentioned JIS standard, but the range according to this is “substantially the same”.
In the duplex applicator of the present invention, a coil spring having a small inner diameter or outer diameter is attached to a thin writing core.
Therefore, when the operating means (operating piece or the like) is operated to project the writing core and the coil spring is compressed, the coil spring does not meander but contracts straight. Therefore, when operating the operating means, the user does not feel a catching feeling or the like.
In addition, the coil springs mounted on the writing cores have substantially the same spring constant. Therefore, in the double applicator of the present invention, the same operational feeling can be felt when any writing core is projected.

  A coil spring having a small inner diameter is attached to the writing core having a small thickness, and the coil diameter of the coil spring having a small inner diameter is preferably larger than the wire diameter of the coil spring having a large inner diameter.

  A coil spring with a small inner diameter is attached to a thin writing core, and the effective number of turns excluding the coiled part of the coil spring with a small inner diameter is larger than the effective number of turns excluding the coiled part of the coil spring with a large inner diameter. It is desirable that the amount be too large.

  A coil spring having a small inner diameter is attached to the writing core having a small thickness, and it is desirable that the coil spring having a small inner diameter has an enlarged portion at the end.

  The invention according to claim 5 is characterized in that the writing core having a smaller thickness is a mechanical pencil unit, and the writing core having a larger thickness is a ball pen refill. The compound writing instrument according to any one of the above.

  According to the present invention, there is no sense of incongruity in the operation of the operating means when moving from the storage position of each writing core having a different thickness to the protruding position.

It is a perspective view of the dual-type writing instrument which concerns on embodiment of this invention, and shows the state which the pen point of any writing core does not protrude from the protrusion opening of the front-end | tip of a shaft cylinder. In FIG. 1, it is a perspective view which shows the state which the pen point of a ball-point pen refill has protruded from the protrusion port. In FIG. 1, it is a perspective view which shows the state which the pen point of a mechanical pencil unit protrudes from the protrusion port. It is sectional drawing of the double-type writing instrument of FIG. It is explanatory drawing which described only the principal part of one ball-point pen refill and the double-type writing instrument engaged with the said ball-point pen refill, (a) shows the state by which the pen point is accommodated in the axial cylinder, (b) The state where the pen tip protrudes from the shaft cylinder is shown. It is explanatory drawing which portrayed only the principal part of a mechanical pencil unit and the compound writing instrument engaged with the said mechanical pencil unit, (a) shows the state by which the pen point is accommodated in the axial cylinder, (b) The state where the pen tip protrudes from the shaft cylinder is shown. It is explanatory drawing which shows the coil spring part of the compound writing instrument of FIG. 1, (a) shows the full length at the time of mounting | wearing of the coil spring with which the mechanical pencil unit is mounted | worn, and the coil spring with which the ball-point pen refill is mounted | worn. (B) shows a state where the coil spring attached to the mechanical pencil unit is buckled when the pen tip of the mechanical pencil unit protrudes from the protruding opening at the tip of the shaft cylinder. It is explanatory drawing which shows the coil spring part of the compound writing instrument of FIG. 1, (a) shows the full length at the time of mounting | wearing of the coil spring with which the mechanical pencil unit is mounted | worn, and the coil spring with which the ball-point pen refill is mounted | worn. (B) shows a state where the coil spring attached to the ballpoint pen refill is buckled when the penpoint of the ballpoint pen refill projects from the projecting opening at the tip of the shaft cylinder. It is the arrow line view seen from the AA direction of the auxiliary member of FIG. It is a side view of the coil spring for ball-point pen refills. It is a side view of the coil spring for mechanical pencil units. It is a model figure of the state by which the coil spring was mounted | worn with the writing core in the conventional compound writing instrument, (a) shows the state of each coil spring when both writing cores are stored in the shaft cylinder and writing is impossible. (B) shows a state in which the coil spring attached to the writing core is compressed and buckled when one of the writing cores protrudes from the shaft cylinder. It is a model figure of the state in which the coil spring of the same standard was each attached to the writing core in which thickness differs in the conventional compound writing instrument, (a) is when writing is impossible when both writing cores are stored in the shaft cylinder (B) shows a state in which the coil spring mounted on the writing core is compressed and buckled when one of the writing cores protrudes from the shaft cylinder. (C) shows a state in which the coil spring mounted on the writing core is compressed and has a meandering shape when one writing core protrudes from the shaft cylinder.

Further embodiments of the present invention will be described below. In the following description, the front-rear relationship will be described with the pen tip side as the front side and the pen shaft side as the rear side.
The dual-type writing instrument of the present embodiment has a plurality of core members built therein and can selectively project them. The dual-type writing instrument of this embodiment is characterized by a coil spring that urges the core member in the axial direction (that is, the rear side). Prior to the description of the characteristic part, an outline of the compound writing instrument will be described, and then the coil spring as the characteristic part will be described in detail.

  As shown in FIGS. 1 to 4, the compound writing instrument 1 of the present embodiment includes a shaft cylinder 2 that is a main body, core members 3 a and 3 b (writing cores) disposed inside the shaft cylinder 2, and a core member. Auxiliary member 4 for holding 3a and 3b movably back and forth at a predetermined position, operation members 5 and 45, two types of coil springs 7 for ball pen refill for urging the core members 3a and 3b backward, sharp A pencil unit coil spring 8 is provided.

  As shown in FIG. 1, the shaft cylinder 2 includes a front cylinder part 12 and a rear cylinder part 13. Spaces are formed in the front cylinder part 12 and the rear cylinder part 13, and the spaces communicate with each other when the front cylinder part 12 and the rear cylinder part 13 are integrally attached. Become.

  The front cylinder portion 12 is a substantially cylindrical member having openings at the front and rear ends, and the portion near the front end becomes narrower as it goes to the front end. The opening formed in the front end portion is an opening serving as a projection port 9 for projecting the front end portion (pen nib portion) of the core member 3 to the outside, and communicates the space formed inside and the outside. .

  Moreover, the opening formed in the rear end portion of the front cylinder portion 12 is an opening having a diameter larger than that of the projecting opening 9 formed in the front end portion, and when the shaft tube 2 is assembled, It will be in the state opened toward the internal space of the cylinder part 13. FIG. Further, in the vicinity of the rear end portion of the front cylinder portion 12, an outer screw (male screw) is formed on the outer peripheral surface thereof. The outer screw can be screwed with an inner screw (female screw) formed on the inner peripheral surface of the rear cylinder portion 13.

  The rear cylinder part 13 is a substantially cylindrical member having an opening at the front end, and the rear end side is closed. In the vicinity of the front end portion of the rear cylinder portion 13, an inner screw (female screw) is formed on the inner peripheral surface thereof. This inner screw can be screwed with the outer screw (male screw) formed in the front cylinder part 12 mentioned above. Further, in the vicinity of the rear end portion of the rear cylinder portion 13, a vertical groove 17 extending along the axial direction of the rear cylinder portion 13 (shaft cylinder 2) is formed.

  The vertical groove 17 penetrates the inside and outside of the rear side cylinder part 13, is formed on the side surface (outer peripheral surface) of the rear side cylinder part 13, and extends forward from the rear end portion of the outer peripheral face. The opening shape of the vertical groove 17 is a substantially vertically long rectangular shape, and the corner portions located at the front end portion and the rear end portion are rounded. That is, the vertical groove 17 is an elongated hole or slit that extends elongated.

  A plurality of the vertical grooves 17 are provided, and are arranged in parallel at intervals in the circumferential direction of the rear cylinder portion 13. And all the vertical grooves 17 have penetrated the side surface of the rear side cylinder part 13, and connected inside and outside. In the present embodiment, four vertical grooves 17 are provided.

  A vertical groove 18 similar to the vertical groove 17 is formed in the vicinity of the rear end portion of the rear cylinder portion 13. Similar to the vertical groove 17, the vertical groove 18 passes through the inside and outside of the rear cylinder part 13, is formed on the side surface (outer peripheral surface) of the rear cylinder part 13, and is forward from the rear end portion of the outer peripheral surface It extends toward. The opening shape of the vertical groove 18 is a substantially vertically long rectangular shape, and the corner portions located at the front end portion and the rear end portion are rounded. In other words, the vertical groove 18 is a long hole or slit extending elongated. The longitudinal groove 18 is slightly longer than the longitudinal groove 17.

  Further, one vertical groove 18 is provided, and a plurality of vertical grooves 17 are arranged in parallel with a plurality of vertical grooves 17 in the circumferential direction of the rear cylinder portion 13. That is, vertical grooves 17 are provided at four of the five locations on the circumference, and vertical grooves 18 are provided at the remaining one location.

Next, the core member 3a will be described.
The core member 3a is the same as a known ballpoint pen refill, and includes a ballpoint pen tip 20 (writing part) and an ink storage cylinder 21 as shown in FIG.

  The ballpoint pen tip 20 has a structure in which a built-in metal ball is rotatably fixed. By rotation of the ball, the ink supplied from the ink storage cylinder 21 is applied to an external writing object (paper or the like). Application is possible.

The ink storage cylinder 21 is a cylindrical body containing ink of a predetermined color inside, and a ballpoint pen tip 20 is integrally fixed to a front end portion thereof. In addition, an opening plug (not shown) is provided inside the ink storage cylinder 21 at a portion slightly closer to the front side than the rear end. The internal space of the ink storage cylinder 21 is divided into two front and rear spaces by the opening plug, and the space located on the front side is filled with ink. The outer diameter of the ink storage cylinder 21 constitutes the outer diameter of the core member 3a.
An operation member 5 described later is integrated with the rear end of the ink storage cylinder 21.

Next, the core member 3b will be described.
The core member 3b is a mechanical pencil unit. As shown in FIG. 6A, the core member 3 b includes a nib unit 31 (writing unit) and a core storage unit 32.

  The nib unit 31 includes a nib feeding mechanism for feeding out the nib (mechanical pencil nib) and constitutes the tip (nib) of the nib member 3b.

The core storage part 32 is a cylindrical part. The front end of the lead accommodating part 32 is opened, and the rear end part of the pen point unit 31 is inserted into the opened front end. That is, the lead accommodating part 32 and the nib unit 31 are integrated so that attachment or detachment is possible.
An operation member 45 to be described later is integrated with the rear end of the lead storage portion 32.

  A plurality of cores (mechanical pencil cores) are built in the core storage portion 32. The lead in the lead storage part 32 is fed out from the nib unit 31 by the lead feeding mechanism.

Next, the auxiliary member 4 will be described.
The auxiliary member 4 shown in FIG. 4 is a member fixed inside the shaft cylinder 2 (rear side cylinder portion 13), and has a plurality (four in this embodiment) of core member holding holes 25 (FIG. 5A). , FIG. 9) and one core member holding hole 26 (FIG. 6A, FIG. 9). The core member holding holes 25 and 26 are holes penetrating the auxiliary member 4 in the front-rear direction. The center-to-center distance F between adjacent adjacent core member holding holes 25 or between the core member holding hole 25 and the core member holding hole 26 is about 3.5 mm.
The core member holding holes 25 and 26 are through holes through which the core members 3a and 3b (writing cores) are inserted, respectively, and function as guides for moving the core members 3a and 3b (writing cores) in the front-rear direction.
A support surface 19 is provided at the rear end of the auxiliary member 4. The support surface 19 functions as a support portion that supports the front ends of coil springs 7 and 8 to be described later.

As shown in FIG. 9, the auxiliary member 4 is provided with four core member holding holes 25 and one core member holding hole 26 at substantially equal intervals. That is, when the center of the four core member holding holes 25 and the center of the core member holding hole 26 are connected, a substantially regular pentagon is formed.
Therefore, each core member holding hole 25 and the core member holding hole 26 are arranged at substantially equal intervals, and the center-to-center distance F between the adjacent core member holding holes 25 or the adjacent core member holding holes 25 and the core member holding. The center-to-center distance F of the holes 26 is substantially the same. That is, the distance between the centers of the adjacent coil springs 7 or between the adjacent coil springs 7 and 8 is F.

  As shown in FIG. 5A, the operation member 5 includes a long and thin operation part main body 42, an operation protrusion 43 that protrudes upward from the upper surface of the operation part main body 42, and an engagement part 44.

The operation portion main body 42 is a substantially rectangular parallelepiped portion extending in the front-rear direction.
The operation protrusion 43 is a protruding portion for the user of the compound writing instrument 1 to operate.
Here, the upper surface of the operation portion main body 42 is a portion that becomes an outer surface when the compound writing instrument 1 is assembled. That is, it can be said that the operation protrusion 43 is a portion protruding outward from the outer surface of the operation portion main body 42. The operation protrusion 43 is formed in a portion near the rear end of the operation portion main body 42, and the protruding end portion has a rounded shape.
The engaging part 44 is a bowl-shaped part provided near the front end of the operation part main body 42.
The engaging portion 44 is integrated with the rear end of the ink storage cylinder 21 of the core member 3a.
The engaging portion 44 is a portion with which a rear end portion of a later-described ballpoint pen refill coil spring 7 abuts.

  As shown in FIG. 6A, the operation member 45 includes a long and thin operation portion main body 46, an operation protrusion 47 that protrudes upward from the upper surface of the operation portion main body 46, and an engagement portion 48.

The operation portion main body 46 is a substantially rectangular parallelepiped portion extending in the front-rear direction.
The operation protrusion 47 is a part where a clip 6 described later is integrally fixed.
Here, the upper surface of the operation portion main body 46 is a portion that becomes an outer surface when the compound writing instrument 1 is assembled. That is, it can be said that the operation protrusion 47 is a portion protruding outward from the outer surface of the operation portion main body 46. The operation protrusion 47 is formed in a portion near the rear end of the operation portion main body 46, and the protruding end portion has a rounded shape.
The engaging part 48 is a bowl-shaped part provided near the front end of the operation part main body 46.
The engaging portion 48 is integrated with the rear end of the core housing portion 32 of the core member 3b.
The engaging portion 48 is a portion with which a rear end portion of a later-described mechanical pencil unit coil spring 8 abuts.

  The clip 6 has a ball portion 6 a at the front end portion, and the ball portion 6 a is in contact with or close to the outer peripheral surface of the shaft tube 2. Further, the rear end portion of the clip 6 is integrally fixed to the operation protrusion 47 of the operation member 45. That is, when the user of the compound writing instrument 1 operates the clip 6, the operation protrusion 47 (operation member 45) moves together with the clip 6.

  Detailed configurations of the ballpoint pen refill coil spring 7 and the mechanical pencil unit coil spring 8 will be described later.

  Next, the assembly structure of the dual-type writing instrument 1 of this embodiment is demonstrated.

As shown in FIG. 4, the auxiliary member 4 is disposed in the rear cylinder portion 13, and the auxiliary member 4 is fixed in the rear cylinder portion 13.
The front cylinder part 12 and the rear cylinder part 13 are screwed together. That is, an external screw formed on the rear end side of the front cylinder portion 12 and an internal screw formed on the front end side of the rear cylinder portion 13 are screwed together, and both are integrated.

  A ball-point refill coil spring 7 is externally fitted to each core member 3a (writing core) which is a ball-point refill. Each core member 3a (ink storage cylinder 21) is inserted into the core member holding hole 25 (FIG. 9) of the auxiliary member 4, and the tip portion (ballpoint pen tip 20) of each core member 3a is shown in FIGS. As shown to (a), it arrange | positions in the front side cylinder part 12. As shown in FIG.

  The operation part main body 42 of the operation member 5 integrated with the rear end of each core member 3a is engaged with the vertical groove 17 (FIGS. 1 and 2) of the rear cylinder part 13, respectively. That is, the operation protrusion 43 of the operation member 5 is fitted in the vertical groove 17, and the operation protrusion 43 that is a part of the operation member 5 arranged inside the rear cylinder portion 13 protrudes from the vertical groove 17 to the outside. It has become a state. Thus, the operation protrusion 43 is in a state in which it can slide along the vertical groove 17.

  As shown in FIGS. 5A and 5B, the ballpoint refill coil spring 7 is disposed between the auxiliary member 4 and the operation member 5 (engagement portion 44) integral with the core member 3a. . The front end of the ballpoint pen refill coil spring 7 is in contact with the support surface 19 of the auxiliary member 4 (FIGS. 5A and 9). Further, the rear end of the ballpoint refill coil spring 7 is in contact with the engaging portion 44 of the operation member 5. That is, the ball pen refill coil spring 7 is slightly compressed between the support surface 19 of the auxiliary member 4 and the engaging portion 44 of the operation member 5.

Similarly, a mechanical pencil unit coil spring 8 is externally fitted to a core member 3b (writing core) which is a mechanical pencil unit. The core member 3b is inserted into the core member holding hole 26 (FIG. 9) of the auxiliary member 4, and the tip portion (pen nib unit 31) of the core member 3b is as shown in FIGS. 4 and 6A. It is arranged in the front cylinder part 12.
The center-to-center distance F of the core member holding holes 25 and 26 of the auxiliary member 4 is substantially the same as the center-to-center distance between the adjacent core members 3a and 3b.

  As shown in FIG. 4, the operation portion main body 46 of the operation member 45 integrated with the rear end of the core member 3 b is engaged with the vertical groove 18 of the rear cylinder portion 13, and the operation member 45 is operated. A protrusion 47 is fitted in the longitudinal groove 18. And the operation protrusion 47 which is a part of the operation member 45 distribute | arranged inside the back side cylinder part 13 is the state which protruded outside from the vertical groove 18. FIG. Therefore, the operation protrusion 47 is in a state in which it can slide along the vertical groove 18.

  As shown in FIGS. 6A and 6B, the mechanical pencil unit coil spring 8 is disposed between the auxiliary member 4 and the operation member 45 (engagement portion 48). The front end of the mechanical pencil unit coil spring 8 fitted on the core member 3b is in contact with the support surface 19 of the auxiliary member 4 (FIGS. 6A and 9). Further, the rear end of the mechanical pencil unit coil spring 8 is in contact with the engaging portion 48 of the operation member 45. That is, both ends of the mechanical pencil unit coil spring 8 are in contact with the engaging portion 48 of the operation member 45 integrated with the support surface 19 of the auxiliary member 4 and the rear end of the core member 3b. The coil spring 8 is compressed.

  Thus, the combination writing instrument 1 of this embodiment will be assembled by combining each member.

Next, the operation of the compound writing instrument 1 will be described.
In the dual writing instrument 1 of the present embodiment, the coil springs 7 and 8 bias the core members 3 a and 3 b toward the inner direction of the shaft tube 2. The compound writing instrument 1 slides the operation protrusions 43 and 47 exposed to the outside of the shaft cylinder 2 against the biasing force of the coil springs 7 and 8 in the front-rear direction, so that the ball-point pen tip 20 (the core member 3a The tip portion) and the nib unit 31 (tip portion of the core member 3b) can be selectively projected and retracted from the projecting opening 9 of the shaft tube 2 (front tube portion 12).

For example, from a state where the ballpoint pen tip 20 (pen tip) is retracted into the shaft cylinder 2, the user resists the urging force of the ball pen refill coil spring 7 with one of the operation projections 43 on the front side (pen tip side). When pressed and slid, the operation member 5 moves to the front side. Along with this, the ink storage cylinder 21 connected to the operation member 5 also moves to the front side, and the ballpoint pen tip 20 integrated with the ink storage cylinder 21 protrudes from the protrusion 9. That is, the ballpoint pen tip 20 moves from the storage position to the protruding position. In the storage position, the ball-point pen tip 20 is stored in the shaft cylinder 2 (front cylinder part 12). At the protruding position, the ball-point pen tip 20 protrudes from the protruding port 9 of the shaft tube 2.
And the position of the core member 3a with respect to the axial cylinder 2 is fixed by the engaging means (not shown), and the state where the ball-point pen tip 20 protrudes from the protrusion 9 is maintained.

  Further, when the ball-point pen tip 20 (pen nib) of the core member 3a is retracted into the shaft cylinder 2 from this protruding state, the engagement by the engagement means (not shown) is released. As a result, the core member 3 a is moved rearward by the urging force of the ballpoint refill coil spring 7, and the ballpoint pen tip 20 is retracted into the shaft cylinder 2. That is, the ball-point pen tip 20 is moved from the protruding position protruding from the protruding port 9 of the shaft cylinder 2 to the storage position in the shaft cylinder 2 (front cylinder portion 12).

  In FIG. 1, all the operation projections 43 are located at the rear end of the vertical groove 17, and the operation projection 47 integral with the clip 6 is located at the rear end of the vertical groove 18. That is, the state where all the ball-point pen tips 20 and the nib unit 31 are housed in the front cylinder portion 12 (shaft cylinder 2) is shown. In FIG. 2, one operation protrusion 43 is located on the front end side of the vertical groove 17, and the state where the ball-point pen tip 20 protrudes from the protrusion 9 is shown.

Similarly, when the operation protrusion 47 (clip 6) of the operation member 45 of the core member 3b located at the rear end of the vertical groove 18 (FIG. 4) is moved forward along the vertical groove 18, FIG. As shown, the nib unit 31 projects from the projecting opening 9 of the shaft tube 2. That is, the nib unit 31 moves from the storage position to the protruding position. In the storage position, the nib unit 31 is stored in the shaft cylinder 2 (front cylinder part 12). At the protruding position, the nib unit 31 protrudes from the protruding port 9 of the shaft cylinder 2.
And the position of the core member 3b with respect to the axial cylinder 2 is fixed by the engaging means (not shown), and the state in which the pen tip unit 31 protrudes from the protrusion 9 is maintained.

  Further, when the pen tip unit 31 (pen tip) of the core member 3b is retracted into the shaft cylinder 2 from the protruding state, the engagement by the engagement means (not shown) is released. As a result, the core member 3 b is moved rearward by the biasing force of the mechanical pencil unit coil spring 8, and the pen tip unit 31 is retracted into the shaft tube 2. That is, the nib unit 31 moves from the protruding position protruding from the protruding port 9 of the shaft cylinder 2 to the storage position in the shaft cylinder 2 (front side cylinder portion 12).

In the dual writing instrument 1 shown in FIG. 1, all the operation members 5 (operation protrusions 43) are located at the rear end of the vertical groove 17 (FIG. 4), and the clip 6 (operation protrusion 47) Located at the rear end. FIG. 1 shows a state in which each ballpoint pen tip 20 and the pen tip unit 31 are housed in the front cylinder portion 12 (shaft cylinder 2).
FIG. 2 shows a state where one of the operation protrusions 43 is located on the front end side of the vertical groove 17 and the ball-point pen tip 20 corresponding to the operation protrusion 43 protrudes from the protrusion 9.
FIG. 3 shows a state in which the operation protrusion 47 is located on the front end side of the vertical groove 18 and the pen tip unit 31 corresponding to the operation protrusion 47 protrudes from the protrusion 9.

  That is, in the dual writing instrument 1, the user operates the operation member 5 integral with any of the core members 3a (ballpoint pen tip 20) or the operation member 45 (clip 6) integral with the core member 3b (pen nib unit 31). As a result, the core member 3a or the core member 3b moves in the front-rear direction (axial direction) of the shaft cylinder 2, and the tip portions (ballpoint pen tip 20, pen point unit 31) of the core members 3a, 3b are moved inside and outside the shaft cylinder 2. It has a structure that appears and disappears. That is, by moving any one of the operation members 5 and 45 forward in the axial direction, the tip end portion (pen nib) of the core member 3a or 3b moves forward, and from the protruding port 9 of the shaft tube 2 to the outside. It is paid out. Further, by moving the operation members 5 and 45 rearward from this state, the tip portions of the core members 3a and 3b move rearward and retreat into the shaft tube 2.

  Next, the coil spring which is a characteristic part of the present invention will be described.

A coil spring 7 which is a coil spring for ballpoint pen refill is mounted on an outer peripheral portion of a core member 3a which is a ballpoint refill.
A coil spring 8 that is a coil spring for the mechanical pencil unit is mounted on the outer peripheral portion of the core member 3b that is the mechanical pencil unit.

  FIG. 7 is a model diagram when two coil springs 7 and 8 having different wire diameters (cross-sectional diameters), coil turns per unit length, and winding diameters (inner diameters) are externally fitted to the core members 3a and 3b. . The coil springs 7 and 8 have different wire diameters (cross-sectional diameters), coil turns per unit length, and winding diameters, but the spring constants are the same (substantially the same).

In FIG. 7 (a) and FIG. 7 (b), depiction of the entire double writing instrument is omitted.
The thickness of the core member 3a that is the ballpoint pen refill is W1, and the thickness of the core member 3b that is the mechanical pencil unit is W2. The core member 3a (ball pen refill) is thicker than the core member 3b (mechanical pencil unit) (W1> W2). The distance between the center (axial core) of the core member 3a and the center (axial core) of the core member 3b is F.

The spring constant of the ballpoint pen refill coil spring 7 is K, the wire diameter (thickness) is d1, the winding number is N1, and the winding diameter (inner diameter) in the natural state is D1.
Here, the number of turns is an effective number of turns excluding end turns (7a, 7b) at both ends of the ball-point refill coil spring 7 and a dense part formed at the center of the coil spring 7 as required. That is, the number of turns is obtained by counting the number of turns of the spiral portion that is elastically deformed in the expansion / contraction direction (axial direction) in the ball-point refill coil spring 7.

  The winding diameter D1 (inner diameter) is the dimension when the ballpoint pen refill coil spring 7 is in a natural state, but the winding diameter D1 is when the ballpoint pen tip 20 moves to the protruding position and the coil spring 7 is compressed and deformed. The coil spring 7 is set to a size that does not take a meandering shape or is difficult to take a meandering shape. That is, when the coil spring 7 is compressed, the clearance C1 between the coil spring 7 and the core member 3a is set so that the coil spring 7 is not easily eccentric in a plurality of directions. When the outer diameter (thickness) of the core member 3a is W1, the clearance C1 is C1 = (D1−W1) / 2.

Although not shown, the natural length of the ballpoint refill coil spring 7 is L.
As shown in FIG. 7A, the length when the coil spring 7 is mounted (the length when the ball-point pen tip 20 is retracted into the shaft cylinder 2) is L1 (L1 <L). That is, the coil spring 7 is slightly contracted.

On the other hand, the mechanical constant of the mechanical pencil unit coil spring 8 is K, the wire diameter is d2, the number of turns is N2, and the winding diameter (inner diameter) in the natural state is D2.
Here, the number of turns is an effective number of turns excluding end turns (8a, 8b) at both ends of the coil spring 8 and a dense part formed at the center of the coil spring 8 as required. That is, the number of turns is obtained by counting the number of turns of the spiral portion that is elastically deformed in the expansion / contraction direction (axial direction) of the coil spring 8.

  The wire diameter d2 is larger than the wire diameter d1 of the coil spring 7 (d2> d1).

  The winding diameter D2 (inner diameter) is a dimension when the mechanical pencil unit coil spring 8 is in a natural state. However, the winding diameter D2 is not meandering when the coil spring 8 is compressed and deformed. Or, it is set to a size that does not easily form a meandering shape. That is, when the coil spring 8 is compressed, the clearance C2 between the coil spring 8 and the core member 3b is set so that the coil spring 8 is not easily eccentric in a plurality of directions. When the outer diameter (thickness) of the core member 3b is W2, the clearance C2 is C2 = (D2-W2) / 2.

Although not shown, the natural length of the mechanical pencil unit coil spring 8 is L.
As shown in FIG. 7A, the length when the coil spring 8 is mounted (the length when the pen tip unit 31 is retracted into the shaft cylinder 2) is L1 (L1 <L). . That is, the coil spring 8 is slightly contracted.

The mechanical pencil unit coil spring 8 and the ballpoint pen refill coil spring 7 are compared as follows.
The lengths of the coil springs 7 and 8 are the same L.
The spring constants K of the coil springs 7 and 8 are substantially the same.
Here, “substantially the same” means that the same range can be said in consideration of manufacturing errors of the coil springs 7 and 8.
The wire diameter d2 of the coil spring 8 is larger than the wire diameter d1 of the coil spring 7 (d2> d1).
The winding diameter D2 of the coil spring 8 is smaller than the winding diameter D1 of the coil spring 7 (D2 <D1).
Although not shown in detail in FIG. 7A, the number of turns N2 per unit length of the coil spring 8 is larger than the number of turns N1 per unit length of the coil spring 7 (N2> N1).

  Next, the positional relationship between the coil springs 7 and 8 and the core members 3a and 3b will be described with reference to FIG.

  As shown in FIG. 7A, the coil spring 7 is fitted on the core member 3 a and is mounted between the auxiliary member 4 and the engaging portion 44 of the operation member 5. The length when the coil spring 7 is mounted is L1 (L1 <L). The coil spring 7 functions as a compression spring.

Further, the length when the coil spring 7 is mounted is L1, and the length when protruding when the ball-point pen tip 20 is protruded from the protrusion 9 (FIG. 2) is L2. That is, the length of the coil spring 7 changes between the length L1 when mounted and the length L2 when protruded.
In other words, the stroke of the operation member 5 is L1-L2.

  Further, the clearance C1 between the coil spring 7 and the core member 3a is C1 = (D1−W1) / 2. That is, there is room for the coil spring 7 to be eccentric from the core member 3a by the clearance C1 from the state in which the axial center of the coil spring 7 and the core member 3a coincides, but the clearance C1 is sufficiently small and the ballpoint pen tip 20 Even if the coil spring 7 protrudes from the shaft cylinder 2 and the coil spring 7 is compressed, the coil spring 7 is unlikely to have a meandering shape as shown in FIG.

  As shown in FIG. 7A, the coil spring 8 is fitted on the core member 3 b and is mounted between the auxiliary member 4 and the engaging portion 48 of the operation member 45. The length when the coil spring 8 is mounted is L1 (L1 <L). The coil spring 8 functions as a compression spring.

  The length when the coil spring 8 is mounted is L1, and the length when protruding when the pen tip unit 31 is protruded from the protrusion 9 (FIG. 3) is L2. That is, the length of the coil spring 7 changes between the length L1 when mounted and the length L2 when protruded.

  In other words, the stroke of the operation member 45 (clip 6) is L1-L2, which is the same as the stroke of the operation member 5. Therefore, the operation feeling of the operation member 5 that operates the core member 3a and the operation member 45 that operates the core member 3b are the same.

  The clearance C2 between the coil spring 8 and the core member 3b is C2 = (D2−W2) / 2. That is, the coil spring 8 has room to be decentered by C2 with respect to the core member 3b from the state where the coil spring 8 and the core member 3b are aligned, but the clearance C2 is sufficiently small, and the nib unit 31 Even if the coil spring 8 protrudes from the shaft cylinder 2 and the coil spring 8 is compressed, the coil spring 8 is unlikely to have a meandering shape as shown in FIG.

In the state shown in FIG. 7A, none of the core members 3a and 3b protrudes from the protruding port 9 (FIG. 1) of the shaft tube 2, and the dual writing instrument 1 cannot write.
When the dual writing instrument 1 shown in FIG. 7A is incapable of writing, that is, when all the core members 3a and 3b are in the storage position, the coil springs 7 and 8 are only F- (d1 + d2 + (D1 + D2) / 2). It is separated. In order to simplify the description, F− (d1 + d2 + (D1 + D2) / 2) = S1.

The compound writing instrument 1 operates as follows.
From the state shown in FIG. 1 and FIG. 7A, that is, from the state in which none of the core members 3 a and 3 b protrudes from the projecting opening 9 (opening) of the shaft cylinder 2, FIG. In the state shown in FIG. 6, that is, when the pen tip unit 31 of the core member 3 b is projected from the protruding port 9, the user corresponds to the core member 3 b shown in FIG. The operating member 45 (clip 6) is operated. That is, the operation member 45 (clip 6) is moved forward.

  As a result, the operation member 45 moves in the distal direction (front side) of the dual writing instrument 1, and the coil spring 8 is pressed by the engaging portion 48 of the operation member 45 and further compressed, and the length in the front-rear direction (axial direction). Becomes L2 (L1> L2). At that time, the coil spring 8 is not necessarily compressed straight in the axial direction, but is biased (buckled), for example, as shown in FIG.

  In this case, as shown in an enlarged view in FIGS. 7A and 7B, the coil spring 8 is compared to the case where the coil spring 8 is compressed straight without buckling. The coil spring 8 and the core member 3b approach each other by the clearance C2 at the maximum.

  However, the winding diameter (inner diameter) D2 of the coil spring 8 fitted on the core member 3b thinner than the core member 3a is larger than the winding diameter (inner diameter) D1 of the coil spring 7 fitted on the core member 3a. The clearance C2 between the coil spring 8 and the core member 3b is sufficiently small.

  Therefore, the coil spring 8 is less likely to have a meandering shape, and hardly approaches the adjacent coil spring 7, and as shown in FIGS. 7 (a) and 7 (b), both the coil springs 7 and 8 are Even when it is closest, it is separated by S2 = S1-C2.

Further, when the nib unit 31 is projected from the shaft cylinder 2 as shown in FIG. 3 and retreated into the shaft cylinder 2 as shown in FIG. There is at least a distance S2 between them, and the coil springs 7 and 8 do not contact each other.
Therefore, the protruding and retracting operations of the core member 3b, which is a mechanical pencil unit, are smooth, and the operation feeling of the operation member 45 (clip 6) is good.

  Next, the case where the ball-point pen tip 20 of the core member 3a projects from the projecting opening 9 of the shaft cylinder 2 will be described.

In the dual writing instrument 1 of the present embodiment, the coil spring 7 shown in FIG. 7A is of the same standard as the conventional coil spring 68 shown in FIG. 12, and further, the adjacent core shown in FIG. 7A. The center-to-center distance F between the members (writing cores) is the same as the center-to-center distance F between the writing cores of the conventional dual writing instrument shown in FIG.
Therefore, even if the coil spring 7 fitted on the core member 3a that moves to the protruding position buckles, it does not come into contact with other adjacent coil springs 7.

  Here, since the coil spring 8 shown in FIG. 8A has a smaller winding diameter than the coil spring 68 shown on the left side of FIG. 12A, the interval S1 between the coil springs 7 and 8 is as shown in FIG. It is larger than the interval S4 between the coil springs 68 shown in a).

That is, as shown in FIG. 8B, when the coil spring 7 is buckled, the distance S3 between the coil spring 7 and the coil spring 8 that are closest to each other is the largest between the coil springs 68 in FIG. It becomes larger than the interval S5 between the close parts.
Therefore, even if the coil spring 7 is compressed and buckled as shown in FIG. 8B, the coil spring 7 cannot contact the coil spring 8.
Therefore, even when the coil spring 7 is compressed (when the ball-point pen tip 20 protrudes from the protrusion 9), the coil spring 7 does not contact any of the other coil springs 7 and 8.

Moreover, the clearance C1 between the coil spring 7 and the core member 3a shown in FIG. 7A is set to a size that does not easily cause a meandering shape when the coil spring 7 is compressed. Therefore, as shown in FIG. 8B, even if the coil spring 7 is compressed, the coil spring 7 is hardly deformed meandering.
As a result, the operation of the operation member 5 is smooth and a good usability can be obtained.

  The natural lengths of the coil springs 7 and 8 and the attached lengths do not necessarily need to match, but it is preferable that the expansion and contraction strokes match. That is, it is preferable that the spring constants of the coil springs 7 and 8 and the expansion / contraction strokes are the same because the operation feeling of the operation members 5 and 45 is the same.

FIG. 10 shows a specific example of a coil spring for ballpoint pen refill.
The ball-point pen refill coil spring 71 shown in FIG. 10 has seven end winding portions 27 and 28 (concentrated portions) at both end portions, and eight central portions 29 at the center portion. The ball-point refill coil spring 71 has 14 turns separately from the end winding parts 27 and 28 and the dense part 29, and the total number of turns is 36. That is, the effective number of turns of the ballpoint refill coil spring 71 is 14 turns. The number of turns of the ballpoint pen refill coil spring 71 can be arbitrarily set regardless of this. As the material of the coil spring 71 for ballpoint pen refill, for example, stainless steel can be adopted.

  The natural length of the ballpoint pen refill coil spring 71 is 26.4 mm, and the length when mounted (the length when mounted) in which the ballpoint pen tip 20 is housed in the shaft tube 2 is mounted in the shaft tube 2. 22.7 mm. And the state (length in use) which made the ball-point pen tip 20 project from the projection port 9 of the shaft cylinder 2 is 8.4 mm. That is, the moving distance (stroke) of the ball-point pen tip 20 in the shaft cylinder 2 is 14.3 mm.

FIG. 11 shows a specific example of the coil spring 72 for the mechanical pencil unit.
The mechanical pencil unit coil spring 72 is different from the ball pen refill coil spring 71 in the number of turns and the winding diameter per unit length.

  That is, by making the effective number of turns of the coil spring 72 having a small winding diameter larger than the effective number of turns of the coil spring 71 having a large winding diameter, the spring constants of both the coil springs 71 and 72 can be made substantially the same.

  Specifically, as shown in FIG. 11, the mechanical pencil unit coil spring 72 has two end winding portions 37 and 38 (concentrated portions) at both ends, and two central portions 39 at the center portion. There is. The mechanical pencil unit coil spring 72 has 28 windings in addition to the end winding portions 37 and 38 and the dense portion 39, and the total number of windings is 34. In other words, the effective number of windings of the mechanical pencil unit coil spring 72 is 28.

  Both end portions including the end winding portion of the mechanical pencil unit coil spring 72 constitute a diameter-expanded portion 36 that slightly increases in diameter toward the end portion.

  The natural length of the mechanical pencil unit coil spring 72 is 28.0 mm, and when the pen tip unit 31 is housed in the shaft tube 2, the attached length (attached length) is 22. 7 mm. And the state (length in use) which made the nib unit 31 protrude from the protrusion port 9 of the axial cylinder 2 is 8.4 mm. Therefore, the moving distance (stroke) of the nib unit 31 in the shaft cylinder 2 is 14.3 mm.

  In other words, the natural length of the coil spring 71 for the ballpoint pen refill and the coil spring 72 for the mechanical pencil unit are different, but the length at the time of mounting (the length in the non-writing state where the pen tip does not protrude from the shaft cylinder 2). )) And the length (8.4 mm) when the pen tip protrudes from the shaft cylinder 2 is in a writable state, and the moving distances (14.3 mm) of the coil springs 71 and 72 are the same. .

  The spring constants of the ballpoint pen refill coil spring 71 and the mechanical pencil unit coil spring 72 are both 0.0035 kgf / mm (0.034 N / mm). That is, the spring constants of the ball pen refill coil spring 71 and the mechanical pencil unit coil spring 72 are the same.

  Since both the springs 71 and 72 have the same spring constant and moving distance (stroke), the user of the dual writing instrument can obtain the same operational feeling when operating either the ballpoint pen refill or the mechanical pencil unit. It is done. However, since the natural lengths of the coil springs 71 and 72 are different, there is a difference in the pressing force required to operate the operation members 5 and 45. That is, of the two coil springs 71 and 72 having the same length when mounted, the coil spring 72 having a longer natural length requires a larger pressing force. However, since the spring constants are the same, the method of changing the pressing force of both coil springs 71 and 72 from the start of movement of the core member to the end of movement is the same. Therefore, the compound writing instrument can give the user a good feeling of use.

  In a compound writing instrument in which a plurality of ballpoint pen refills and one mechanical pencil unit are mixed, the clip 6 is not attached to the operation member 45, and all the core members 3a and 3b are operated by the same operation member 5. Even in this case, as described above, by providing a difference in the necessary pressing force, the user can recognize that the core member 3b corresponding to the specific operation member 5 is a mechanical pencil unit. .

  The core member 3a and the core member 3b have different outer diameters (thicknesses), and the core member 3a is thicker. For example, the outer diameter of the core member 3a is 2.6 mm, and the outer diameter of the core member 3b is 2.3 mm. Coil springs 71 and 72 as described below can be attached to these core members 3a and 3b.

The ball pen refill coil spring 71 mounted on the core member 3a has an outer diameter of 3.05 mm, an inner diameter of 2.65 mm, and a wire diameter (thickness) of 0.2 mm.
The outer diameter of the mechanical pencil unit coil spring 72 (excluding the enlarged diameter portions 36 at both ends) attached to the core member 3b is 3.1 mm, the inner diameter is 2.64 mm, and the wire diameter (thickness) is 0. .23 mm.

That is, a coil spring 72 having a small inner diameter is attached to the thin core member 3b.
By attaching the coil spring 72 having a small inner diameter to the core member 3b having a small thickness, the clearance between the core member 3b and the coil spring 72 is reduced, and when the coil spring 72 is compressed, the coil spring 72 meanders. It becomes difficult to deform or to contact other adjacent coil springs 71.

  Further, not only the inner diameter of the coil spring 72 but also the outer diameter may be reduced. That is, when the outer diameter of the coil spring 72 is small, the distance between the adjacent coil springs 71 is widened, and the coil springs 72 are less likely to come into contact with the other coil springs 71. For example, if the wire diameter (thickness) of the coil spring 72 is reduced, both the inner diameter and the outer diameter of the coil spring 72 can be reduced, and the effect is high.

Further, enlarged diameter portions 36 are provided at both ends of the mechanical pencil unit coil spring 72 having a small inner diameter.
The coil spring 72 is easily seated on the support surface 19 of the auxiliary member 4 and the engaging portion 48 of the operation member 45 by the enlarged diameter portions 36 at both ends, and the position is easily fixed. Therefore, the expansion / contraction operation of the coil spring 72 is stabilized.

Further, the wire diameter (thickness) of the coil spring 72 having a small inner diameter (winding diameter) is thicker than the wire diameter (thickness) of the coil spring 71 having a large inner diameter (winding diameter). For example, the wire diameter (thickness) of the coil spring 72 having a small inner diameter (winding diameter) is 0.23 mm, and the wire diameter (thickness) of the coil spring 71 having a large inner diameter (winding diameter) is 0.2 mm.
Thus, by setting the wire diameters of the two coil springs 71 and 72, the spring constants of the two coil springs 71 and 72 can be easily set to be substantially the same.

  In the above-described embodiment, the case where the core members 3a and 3b are ballpoint pen refills and mechanical pencil units has been described. However, the present invention can be applied to various modes regardless of this. For example, all the core members may be ballpoint pen refills, a specific color (for example, black) may be thickened, and other colors may be thinned. Further, the number of thick core members 3a and the number of thin core members 3b can be arbitrarily set. For example, in the case of a five-color ballpoint pen, the three colors may be assigned to the thick core member 3a, and the remaining two colors may be assigned to the thin core member 3b.

  Further, as the core member, for example, a touch pen for operating the touch panel may be used. Further, the core member may be an applicator (so-called correction pen) that corrects a written character by applying a white pigment. That is, the core member is used for writing characters or the like (characters, designs, symbols) on an external writing object, or for erasing and correcting the written characters.

1 Duplex writing instrument 2 Shaft cylinder 3a Core member (Ball pen refill writing core)
3b Core member (writing core of mechanical pencil unit)
5 Operation members (operation means)
7 Coil spring for ballpoint pen refill 8 Coil spring for mechanical pencil unit 9 Protruding port (opening)
20 Ballpoint pen tip (writing part)
31 Nib tip (writing part)

Claims (5)

A shaft cylinder having an open tip and a hollow portion inside, a plurality of writing cores having a writing portion at the tip, a plurality of coil springs, and a plurality of operating means,
The plurality of writing cores are arranged in the shaft cylinder in a state where the coil springs are mounted on the outer peripheral portion of each writing core, and each writing core is urged toward the inside of the shaft cylinder by the coil springs. In the dual writing instrument that selectively protrudes the writing core from the opening at the tip by operating the operating means,
Some coil springs have substantially the same spring constant and different inner diameters or outer diameters.
What is different in thickness is mixed in the said writing core, and the coil writing spring with which at least one of an internal diameter or an outer diameter is small is mounted | worn with a thin writing core.   2. A coil spring having a small inner diameter is attached to the writing core having a small thickness, and the wire diameter of the coil spring having a small inner diameter is larger than the wire diameter of the coil spring having a large inner diameter. The double writing instrument described.   A coil spring with a small inner diameter is attached to a thin writing core, and the effective number of turns excluding the coiled part of the coil spring with a small inner diameter is larger than the effective number of turns excluding the coiled part of the coil spring with a large inner diameter. The compound writing instrument according to claim 1 or 2, wherein there are also many.   4. A coil spring having a small inner diameter is attached to a thin writing core, and the coil spring having a small inner diameter has an enlarged diameter portion at an end. A double writing instrument as described in 1.   The compound writing instrument according to any one of claims 1 to 4, wherein the writing core having a smaller thickness is a mechanical pencil unit, and the writing core having a larger thickness is a ballpoint pen refill.

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