JP7265938B2 - mechanical pencil - Google Patents

Description

The present invention relates to mechanical pencils.

There is known a mechanical pencil in which a tip pipe disposed at the tip of a writing part retreats as the writing lead wears by writing while the tip pipe is in contact with a writing surface (Patent Document 1).

JP-A-8-230382

In order to effectively use the mechanical pencil described in Patent Document 1, it is preferable that the amount of protrusion of the writing lead is smaller than that of a normal mechanical pencil. That is, if the amount of protrusion of the writing lead is increased, the tip pipe will not be retracted in accordance with the wear of the writing lead, and not only will the mechanical pencil not be used effectively, but the writing lead will likely break. However, some users habitually increase the amount of projection, have a preconceived notion that contacting the tip pipe with the writing surface impairs the writing feeling, or do not know how to use it. may occur.

The present invention provides a mechanical pencil in which the tip pipe retracts in accordance with the wear of the writing lead by writing with the tip pipe in contact with the writing surface, and the sharpening tip is automatically adjusted to an appropriate projection of the writing lead. The purpose is to provide a pencil.

According to one aspect of the present invention, a barrel, a tip pipe disposed at a front end of the barrel and arranged to be movable back and forth with respect to the barrel, a holding chuck for holding a writing lead, and a writing and a ball chuck that allows the lead to move forward and prevents it from retreating, and the tip pipe is retracted in accordance with the wear of the writing lead by writing while the tip pipe is in contact with the writing surface. Further provided is a mechanical pencil characterized by further comprising a ball chuck retracting mechanism for retracting the ball chuck together with the writing lead by writing pressure due to writing after a knocking operation.

The ball chuck retracting mechanism has a ball chuck holder that holds the ball chuck, and a knock cylinder that is arranged so as to be movable back and forth with respect to the shaft cylinder and that surrounds the ball chuck holder so as to be movable back and forth. Advancement and retreat of the ball chuck may be regulated by a chuck holder, and advance of the ball chuck may be regulated by engaging the knock cylinder with the ball chuck holder when the ball chuck advances. . The knock cylinder may be biased rearward. The ball chuck retracting mechanism may have a ball chuck holder that holds the ball chuck, and the ball chuck holder may restrict forward and backward movement of the ball chuck. An elastic member for urging the tip pipe forward is further provided, and when the writing pressure is released in a state where the tip pipe is retracted due to wear of the writing lead, the urging force of the elastic member urges the tip pipe and the tip pipe. The writing lead held by the holding chuck may move forward.

According to the aspect of the present invention, in a mechanical pencil in which the tip pipe retreats according to the wear of the writing lead by writing while the tip pipe is in contact with the writing surface, the writing lead is automatically adjusted to an appropriate protrusion amount. It has the common effect of providing a mechanical pencil that is calibrated.

1 is a perspective view of a mechanical pencil according to an embodiment of the present invention; FIG. FIG. 2 is a longitudinal sectional view of the mechanical pencil. FIG. 3 is an enlarged sectional view of the front half of the mechanical pencil. FIG. 4 is a perspective view of a ball chuck holder. FIG. 5 is a perspective view of a knock cylinder. FIG. 6 is another enlarged cross-sectional view of the front half of the mechanical pencil. FIG. 7 is yet another enlarged cross-sectional view of the front half of the mechanical pencil. FIG. 8 is yet another enlarged cross-sectional view of the front half of the mechanical pencil. FIG. 9 is yet another enlarged cross-sectional view of the front half of the mechanical pencil. FIG. 10 is yet another enlarged cross-sectional view of the front half of the mechanical pencil. FIG. 11 is an enlarged cross-sectional view of the front half of a mechanical pencil according to another embodiment of the present invention; FIG. 12 is an enlarged perspective view of the front end of the mechanical pencil;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Corresponding elements are provided with common reference numerals throughout the drawings.

1 is a perspective view of a mechanical pencil 1 according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the mechanical pencil 1, and FIG. 3 is an enlarged sectional view of the front half of the mechanical pencil.

A mechanical pencil 1 has a front barrel 2, a rear barrel 3 screwed onto the outer peripheral surface of the rear end portion of the front barrel 2, and a tip member 4 screwed onto the outer peripheral surface of the front end portion of the front barrel 2. there is The front axle 2 and the rear axle 3 constitute a barrel tube 5 . In addition, you may call the shaft cylinder 5 including the tip member 4. As shown in FIG. A front end pipe 6 is arranged in the front end portion of the barrel 5 , that is, inside the tip member 4 so as to be movable back and forth with respect to the barrel 5 . In other words, the tip pipe 6 is arranged at the tip of the writing part of the mechanical pencil 1 . The tip pipe 6 is configured so that a writing lead 7 can be inserted therethrough. In this specification, in the axial direction of the mechanical pencil 1, the writing lead 7 side is defined as the "front" side, and the side opposite to the writing lead 7 side is defined as the "rear" side.

A holding chuck 8 having a through hole formed in the center is arranged inside the tip pipe 6 . The through hole of the holding chuck 8 slidably contacts the outer peripheral surface of the writing lead 7 and acts to temporarily hold the writing lead 7 . The tip pipe 6 is biased forward by a coil spring 9 .

A mechanical pencil 1 has a ball chuck 10 for gripping a writing lead 7 . Referring to FIG. 3, the ball chuck 10 includes a cylindrical fastener 11, a chuck main body 12 disposed in the fastener 11, a cylindrical chuck holder 13, and a plurality of chuck holders 13. a ball 14; A tapered surface that widens forward is formed on the inner peripheral surface of the fastener 11 . The chuck main body 12 has a through hole for the writing lead 7 formed along the central axis, and the front end of the chuck main body 12 is divided into a plurality of parts along the axial direction. A rear end portion of the chuck body portion 12 is held by a chuck holding portion 13 . The chuck body portion 12 and the chuck holding portion 13 are axially movable with respect to the fastener 11 . The plurality of balls 14 are arranged between the inner peripheral surface of the fastener 11 and the outer peripheral surface of the chuck body portion 12 .

When writing pressure is applied to the writing lead 7 , the writing lead 7 is gripped by the chuck body 12 because the chuck main body 12 and the balls 14 come into contact with the tapered surface inside the cylindrical fastener 11 . This prevents the writing lead 7 from retreating. On the other hand, when a force is exerted to draw the writing lead 7 forward, the chuck main body 12 is not affected by the fastener 11, so the writing lead 7 can be drawn forward without resistance. That is, the ball chuck 10 acts so as to allow the writing lead 7 to advance and prevent it from retreating.

A coil spring 15 is arranged to surround the chuck main body 12 . A rear end of the coil spring 15 is fitted to the outer surface of the chuck body 12 , and a front end of the coil spring 15 is supported by a step formed on the inner peripheral surface of the fastener 11 . The coil spring 15 biases the chuck main body 12 rearward, and as a result, the ball chuck 10 can maintain the state of gripping the writing lead 7 . Also, the chuck holding portion 13 is urged rearward by a coil spring 16 .

Inside the tip member 4, a core protection member 17 that can move back and forth within the tip member 4, and a fixing ring 18 fixedly attached to the tip member 4 behind the core protection member 17 are arranged. there is The rear portion of the lead protecting member 17 surrounds the front end portion of the fastener 11 , and the front portion of the lead protecting member 17 is formed to surround the writing lead 7 . The coil spring 9 that urges the tip pipe 6 forward urges the core protection member 17 rearward by coming into contact with the front surface of the core protection member 17 . Retraction of the core protection member 17 is restricted by contact with the front end surface of the fixing ring 18 .

A rear end portion of the fastener 11 is connected to a front end portion of a cylindrical ball chuck holder 20 . That is, the outer peripheral surface of the rear end portion of the fastener 11 is fitted to the inner peripheral surface of the front end portion of the ball chuck holder 20 . A cylindrical knock cylinder 21 is arranged to surround the ball chuck holder 20 . Here, the ball chuck holder 20 and the knock cylinder 21 will be described with reference to FIGS. 4 and 5. FIG.

4 is a perspective view of the ball chuck holder 20. FIG. In FIG. 4, the mechanical pencil 1 is arranged so that the upper side is the rear side. The ball chuck holder 20 formed in a cylindrical shape has a first large diameter portion 201 formed to have a large diameter and a first large diameter portion 201 formed to have a diameter smaller than that of the first large diameter portion 201 in front of the first large diameter portion 201 . 1 small diameter portion 202 . Two annular protrusions 203 are formed on the outer peripheral surface of the first large-diameter portion 201 and are spaced apart in the axial direction. Two opposing slits 204 are formed in the axial direction of the first large diameter portion 201 from the rear end surface of the ball chuck holder 20 toward the front to divide the first large diameter portion 201 into two. A rectangular through-hole 205 is formed between two annular projections 203 in each of the divided first large-diameter portions 201 . A stepped portion 206 facing rearward is provided on the inner surface of the first small diameter portion 202 (FIG. 3).

5 is a perspective view of the knock cylinder 21. FIG. In FIG. 5, the mechanical pencil 1 is arranged so that the upper side is the rear side. The knock cylinder 21 formed in a cylindrical shape has a second large-diameter portion 211 formed to have a large diameter and a second large-diameter portion 211 formed to have a smaller diameter than the second large-diameter portion 211 in front of the second large-diameter portion 211 . and a small diameter portion 212 .

Referring to FIG. 3 again, the ball chuck holder 20 is arranged in the knock cylinder 21 so as to be movable back and forth. Advancement of the ball chuck holder 20 is restricted by the front end surface 207 of the first large diameter portion 201 engaging with an engaging surface 213 provided on the inner surface of the knock cylinder 21 and facing rearward. When the ball chuck holder 20 moves backward, the rear end surface 208 of the ball chuck holder 20 comes into contact with the contact surface provided inside the barrel 5, specifically, the contact surface 2a provided inside the front shaft 2. regulated by

The knock cylinder 21 is biased rearward by a coil spring 22 . That is, the front end of the coil spring 22 is supported by the rear end surface 4 a of the tip member 4 , and the rear end of the coil spring 22 contacts the front end surface 214 of the second large diameter portion 211 of the knock cylinder 21 . The knock cylinder 21 is arranged in the front shaft 2 so as to be movable back and forth. The forward movement of the knock tube 21 is restricted by the contact of the front end face 215 of the knock tube 21 with the rear end face 4 a of the tip member 4 . Retraction of the knock tube 21 is restricted by the rear end surface 216 of the knock tube 21 coming into contact with the contact surface 2 a of the front shaft 2 .

A locking projection 131 is provided on the outer surface of the chuck holding portion 13 . The locking projection 131 protrudes into the through hole 205 of the ball chuck holder 20 . Since the front end of the coil spring 16 is supported by the stepped portion 206 of the ball chuck holder 20 , the chuck holding portion 13 is urged rearward, and the locking protrusion 131 is locked to the end face of the through hole 205 . As a result, the chuck holding portion 13, that is, the ball chuck 10 and the ball chuck holder 20 always move back and forth together. In other words, the ball chuck 10 is held by the ball chuck holder 20 . The front end portion of the lead case 23 is loosely fitted to the outer peripheral surface of the rear end portion of the chuck holding portion 13 . Therefore, the chuck holder 13 and lead case 23 are relatively movable along the axial direction. The lead case 23 is formed in a cylindrical shape and accommodates the writing lead 7 therein.

Referring to FIG. 2 again, a knock rod 24 as a knock member is provided at the rear end portion of the barrel 5, specifically at the rear portion of the rear axle 3, so as to be movable back and forth with respect to the barrel 5. As shown in FIG. The knock bar 24 is urged rearward by a coil spring 25 . An eraser 26 is detachably mounted inside the rear end portion of the knock rod 24 . A knock cover 27 is detachably attached to the outer peripheral surface of the rear end portion of the knock rod 24 to protect the eraser 26 from dirt and the like. The knock bar 24 is fitted to the outer peripheral surface of the rear end portion of the lead case 23 .

Next, the operation of the mechanical pencil 1 will be described while sequentially referring to FIGS.

FIG. 6 shows the state of the mechanical pencil 1 shown in FIG. 3 during the knocking operation. The knocking operation is performed by pressing forward the knock bar 24 or the knock cover 27, which is the knock portion. The lead case 23 advances by the knocking operation, and the ball chuck 10 advances when the front end surface of the lead case 23 comes into contact with the chuck holding portion 13 . As the ball chuck 10 advances, the core protection member 17 advances due to contact with the front end of the fastener 11 , and the ball chuck holder 20 advances due to contact with the front end of the coil spring 16 . When the ball chuck holder 20 advances, the knock cylinder 21 advances due to engagement with the front end surface 207 of the ball chuck holder 20 .

The forward movement of the knock cylinder 21 is restricted by the proboscis member 4, and the forward movement of the ball chuck holder 20 is restricted by the engaging surface 213 of the knock cylinder 21 in the restricted state. In other words, the knock cylinder 21 regulates the advancement of the ball chuck 10 and the ball chuck holder 20 . In a state where the forward movement of the ball chuck holder 20 and the knock cylinder 21 is restricted, if the knock portion is further pressed against the urging force of the coil spring 15 and the coil spring 16, the ball chuck 10 is further advanced and the writing lead is pushed forward. 7 is rolled out. That is, by further pressing, the chuck holding portion 13 is pushed forward with respect to the ball chuck holder 20 in the regulated state. Along with this, the writing lead 7 gripped by the chuck main body 12 also moves forward, acting to let out the writing lead 7 from the tip pipe 6 .

FIG. 7 shows a state in which the knocking operation of the mechanical pencil 1 shown in FIG. 6 has been completed. That is, when the forward pressure of the knock bar 24 or the knock cover 27 is released, the urging force of the coil spring 25 causes the knock bar 24 to retreat and return to its original position. At this time, the chuck main body 12 retreats due to the biasing forces of the coil springs 15 and 16 . On the other hand, since the writing lead 7 is held by the holding chuck 8 , the writing lead 7 is pulled out from the chuck main body 12 without resistance as the action of the ball chuck 10 . As a result, since the writing lead 7 is extended from the tip pipe 6, the writing lead 7 can be extended by a predetermined amount each time the knocking operation is repeated.

When the knock rod 24 is kept forward by the knocking operation, the chuck main body 12 protrudes from the fastener 11 and the writing lead 7 is released. In this state, the writing lead 7 that has been extended from the tip pipe 6 can be pushed back with a fingertip or the like.

When the knocking operation is completed, the core protection member 17 is retracted by the biasing force of the coil spring 9 until it abuts against the fixing ring 18 . Further, the biasing force of the coil spring 22 causes the knock cylinder 21 to move backward until it contacts the contact surface 2 a of the front shaft 2 . At this time, the ball chuck holder 20 retreats together with the knock cylinder 21 due to engagement with the engaging surface 213 of the knock cylinder 21 .

FIG. 8 shows a state immediately after writing is started with the mechanical pencil 1 shown in FIG. 7 and writing pressure is applied to the writing lead 7 . When writing pressure is applied to the writing lead 7 by writing after the knocking operation, the ball chuck 10 retreats together with the writing lead 7 and the ball chuck holder 20 . Retraction of the ball chuck 10 is regulated by the contact of the ball chuck holder 20 with the contact surface 2 a of the front shaft 2 . By retracting the writing lead 7, the amount of protrusion of the writing lead 7 from the tip pipe 6 is relatively reduced. Therefore, the front end of the tip pipe 6 abuts the writing surface, and the tip pipe 6 retreats against the biasing force of the coil spring 9 (FIG. 9).

FIG. 10 shows a state in which writing is completed and the writing pressure is released. When the writing pressure is released, the urging force of the coil spring 9 advances the tip pipe 6 . At this time, since the writing lead 7 is held by the holding chuck 8 , the writing lead 7 is pulled out from the ball chuck 10 .

According to the mechanical pencil 1 in the state shown in FIG. 10, by writing with the tip pipe 6 in contact with the writing surface, the tip pipe 6 retreats according to the wear of the writing lead 7, so that the knocking operation is not required. You can write for a long time without doing it. Furthermore, when the writing pressure is released with the tip pipe 6 retracted according to the wear of the writing lead 7, the tip pipe 6 and the writing lead 7 held by the holding chuck 8 advance due to the biasing force of the coil spring 9. , the writing lead 7 is fed out. Therefore, it is possible to write for a longer time without knocking. When the knocking operation is performed again, the mechanical pencil 1 returns to the state shown in FIG. 6, and this is repeated thereafter.

In the ball chuck holder 20 , a static frictional force is generated between the annular projection 203 and the inner surface of the knock cylinder 21 by contacting the inner surface of the knock cylinder 21 . The static friction force due to the annular projection 203 is greater than the force required to pull the writing lead 7 out of the ball chuck 10 and less than the force acting on the ball chuck holder 20 with normal or relatively weak writing pressure. is preferred. If the static friction force is smaller than the force required to pull the writing lead 7 out of the ball chuck 10, not only the writing lead 7 but also the ball chuck 10 advance when the writing pressure is released. Moreover, if the static friction force is too large, the ball chuck 10 or the ball chuck holder 20 cannot be retracted. An annular projection may be provided on the inner surface side of the knock cylinder 21 instead of the annular projection 203 of the ball chuck holder 20 .

Since the ball chuck 10 or the ball chuck holder 20 is not biased forward, it moves forward only by the knocking operation. Also, since the ball chuck 10 or the ball chuck holder 20 is not fully urged backward, it is retracted to the retraction limit position only by the writing pressure.

The ball chuck holder 20 and the knock cylinder 21 constitute a ball chuck retracting mechanism that retracts the writing lead 7 that has protruded excessively due to excessive knocking operation together with the ball chuck 10 . As described above, the ball chuck retraction mechanism is actuated by writing pressure due to writing after the knocking operation.

The ball chuck retraction mechanism can define the amount of retraction of the writing lead 7 and the ball chuck 10 by determining the amount of back and forth movement of the ball chuck holder 20 and the knock cylinder 21 . 6, the ball chuck holder 20 and the knock cylinder 21 are at the forward limit position, and in FIG. 10, the ball chuck holder 20 and the knock cylinder 21 are at the backward limit position. Therefore, as shown in FIG. 6, the ball chuck holder 20 is movable by a distance L1, and the knock cylinder 21 is movable by a distance L2. As shown in FIG. 7, the knock cylinder 21 is already at the retraction limit position after the knock operation. Therefore, the ball chuck holder 20, that is, the ball chuck 10, has room to retreat by the distance L1-L2. Therefore, by defining the possible amount of back and forth motion of the ball chuck holder 20 and the knock cylinder 21 so that the distance L1-L2 becomes an appropriate value, the retraction amount of the ball chuck 10 and, in turn, the writing lead 7 can be set to a predetermined value. can be set to

Since the mechanical pencil 1 has a ball chuck retraction mechanism, the amount of protrusion of the writing lead 7 suitable for the mechanical pencil 1 is automatically adjusted. That is, according to the ball chuck retraction mechanism, by writing while the tip pipe 6 is in contact with the writing surface, the mechanical pencil which is constructed so that the tip pipe 6 is retracted according to the wear of the writing lead 7 can be effectively used. The amount of protrusion of the writing lead 7 that can be used can be set appropriately. In addition, it is possible to prevent breakage of the writing lead 7 that protrudes too much. The ball chuck retraction mechanism may be applied to a mechanical pencil whose tip pipe does not retract. Also, the ball chuck retraction mechanism may be arbitrarily configured as long as the ball chuck 10 can be retracted together with the writing lead by the writing pressure due to writing after the knocking operation.

FIG. 11 is an enlarged cross-sectional view of the front half of mechanical pencil 100 according to another embodiment of the present invention. The mechanical pencil 100 according to this embodiment differs from the mechanical pencil 1 according to the above-described embodiment only in that the ball chuck holder 20 and the knock cylinder 21 are integrally formed. In other words, the mechanical pencil 100 has a ball chuck holder 30 integrally formed with a knock cylinder. The ball chuck holder 30 constitutes a ball chuck retracting mechanism that retracts the writing lead 7 that has protruded excessively due to excessive knocking operation together with the ball chuck 10 .

The ball chuck holder 30 is configured similarly to the ball chuck 10 . That is, the ball chuck holder 30 formed in a cylindrical shape has a first large diameter portion 301 formed to have a large diameter, and a front portion of the first large diameter portion 301 formed to have a diameter smaller than that of the first large diameter portion 301 . and a first small diameter portion 302 . Two annular protrusions 303 are formed on the outer peripheral surface of the first large-diameter portion 301 and are spaced apart in the axial direction. Two slits (not shown) facing each other are formed in the axial direction of the first large diameter portion 301 from the rear end surface of the ball chuck holder 30 toward the front to divide the first large diameter portion 301 into two. ing. A rectangular through-hole 305 is formed between two annular projections 303 in each of the divided first large-diameter portions 301 . A stepped portion 306 facing rearward is provided on the inner surface of the first small diameter portion 302 .

Since the operation of the mechanical pencil 100 is substantially the same as the operation of the mechanical pencil 1 described above, it will be briefly described. That is, the ball chuck 10 and the ball chuck holder 30 advance by the knocking operation. Advancement of the ball chuck holder 30 is restricted by the complete compression of the coil spring 22 . Further, the forward movement of the ball chuck holder 30 may be restricted by contacting the front end surface of the ball chuck holder 30 with the rear end surface of the fixing ring 18 .

When the knocking operation is completed, the ball chuck holder 30 is slightly retracted by the biasing force of the coil spring 22 . At this time, the retraction of the ball chuck holder 30 is stopped by the frictional force between the annular protrusion 303 and the inner surface of the shaft cylinder 5 . When writing is started in this state, that is, by writing after the knock operation, writing pressure is applied to the writing lead 7 , the ball chuck 10 retreats together with the writing lead 7 and the ball chuck holder 30 . Retraction of the ball chuck 10 is regulated by the contact of the ball chuck holder 30 with the contact surface 2 a of the front shaft 2 .

According to the mechanical pencil 100, compared with the mechanical pencil 1 according to the above-described embodiment, a similar ball chuck retracting mechanism can be realized with a smaller number of parts.

FIG. 12 is an enlarged perspective view of the front end of the mechanical pencil 1. FIG. In the mechanical pencil 1, the tip pipe 6 is a member made of hard plastic such as polycarbonate, and is transparent or translucent. Therefore, the writing lead 7 is visible from the outside of the tip pipe 6, especially in the writing portion.

As a result, particularly when the writing lead 7 is a colored lead other than black, the color of the colored lead can be determined without looking at the handwriting. Also, regardless of the color of the writing lead 7, when writing is about to be performed, is the writing lead 7 arranged inside the tip pipe 6? , can be determined. Since the protruding amount of the writing lead 7 can be visually recognized well, the writing lead 7 will not break due to excessively increasing the protruding amount.

Furthermore, the front end of the tip pipe 6 is formed in a conical shape. As a result, compared to a general metal cylindrical tip pipe, the front end portion has a shaved tip that looks like a pencil, which has the effect of giving an impression of a softer appearance.

The mechanical pencil 1 described above has the coil spring 9 for urging the tip pipe 6 forward, but the present invention does not have the coil spring 9, and the tip pipe is simply attached to the barrel. The present invention can also be applied to mechanical pencils arranged to be movable back and forth, that is, so-called slide pipe type mechanical pencils. Also, each of the coil springs described above may be replaced with other elastic members.

Reference Signs List 1 mechanical pencil 2 front barrel 3 rear barrel 4 nose member 5 barrel 6 tip pipe 7 writing lead 8 holding chuck 9 coil spring 10 ball chuck 11 fastener 12 chuck main body 13 chuck holding portion 14 ball 15 coil spring 16 coil spring 17 Lead protection member 18 Fixing ring 20 Ball chuck holder 21 Knock cylinder 22 Coil spring 23 Lead case 24 Knock bar 25 Coil spring 26 Eraser 27 Knock cover

Claims (8)

an axle tube;
a tip pipe disposed at a front end portion of the shaft cylinder and arranged so as to be movable back and forth with respect to the shaft cylinder;
a holding chuck for holding a writing lead;
a ball chuck that allows the writing lead to advance and prevents it from retreating;
A mechanical pencil configured such that the tip pipe is retracted in accordance with the wear of the writing lead by writing while the tip pipe is in contact with the writing surface,
A mechanical pencil, further comprising a ball chuck retracting mechanism for retracting the ball chuck together with the writing lead with respect to the holding chuck by writing pressure due to writing after a knocking operation. The ball chuck retracting mechanism has a ball chuck holder that holds the ball chuck, and a knock cylinder that is arranged to be movable back and forth with respect to the shaft cylinder and that surrounds the ball chuck holder so as to be movable back and forth,
The ball chuck holder regulates forward and backward movement of the ball chuck,
2. The mechanical pencil according to claim 1, wherein the forward movement of the ball chuck is restricted by engaging the knock cylinder with the ball chuck holder during the forward movement of the ball chuck. 3. The mechanical pencil according to claim 2, wherein said knock barrel is biased rearward. 2. The mechanical pencil according to claim 1, wherein the ball chuck retreat mechanism has a ball chuck holder that holds the ball chuck, and the ball chuck holder regulates forward and backward movements of the ball chuck. further comprising an elastic member that biases the tip pipe forward;
When the writing pressure is released in a state in which the tip pipe is retracted due to wear of the writing lead, the tip pipe and the writing lead held by the holding chuck are advanced by the urging force of the elastic member. 5. The mechanical pencil according to any one of 4. Equipped with a writing core,
6. The mechanical pencil according to any one of claims 1 to 5, wherein the tip pipe is transparent or translucent, and the writing lead is visible from the outside of the tip pipe. 7. The mechanical pencil according to claim 6, wherein the front end of said tip pipe is conical. 8. The mechanical pencil according to claim 6 or 7, wherein said writing lead is a colored lead other than black.

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