Knocking writing utensil

Abstract: A knocking writing utensil that improves a knocking operability and that enables a writing utensil to automatically return to a withdrawal position when a clip is used. An engagingly-locking protrusion 26a is formed on an engagement body 26 that moves inside an external cylinder 12 together with a refill 20, and an engaging-lock receiving protruding portion 28b including an engaging-lock receiving portion at its front end is formed on the rear surface of a non-proximal end of a clip 28 with its proximal end fixed to the external cylinder 12. A guide hole 12a is formed in the external cylinder 12 so as to correspond to the engaging-lock receiving protruding portion 28b. A cam portion 25a that can abut on the engagingly-locking protrusion 26a is formed on a knock bar 25 integrated with a knock body 24. The cam portion 25a moves the engagingly-locking protrusion 26a beyond the engaging-lock receiving protruding portion 28b from behind it to the engaging-lock receiving portion, or guides the engagingly-locking protrusion 26a from the engaging-lock receiving portion to behind the engaging-lock receiving protruding portion 28b in such a way as to pass by one lateral side of the engaging-lock receiving protruding portion 28b.

Description: The present invention relates to a knocking writing utensil comprising an external cylinder a writing medium, an elastic body, a clip and an engagement body according to the generic part of claim 1. Description of the Prior Art Known knocking writing utensils conventionally comprises an external cylinder, a writing medium inserted and housed in the external cylinder so as to be moved in the axial direction, an elastic body for urging the writing medium rearward, a clip with its proximal end fixed to the external cylinder, and a knock body that is exposed outwardly from the external cylinder to be knocked. The knock body is operated to move the writing medium from a withdrawal position at which it is withdrawn into the external cylinder to a forward position at which its tip protrudes from the tip of the external cylinder. BRIEF SUMMARY OF THE INVENTION Object of the Invention If a user forgets to withdraw the writing medium and houses such a conventional knocking writing utensil in a pocket of the user's jacket by clipping the writing utensil to the edge of the pocket, then the writing medium may stain the pocket or make a hole therein. A knocking writing utensil that solves this problem is described in the applicant's Japanese Utility Model Publication No. 5-25915 and Japanese Utility Model Publication No. 6-15735. In the knocking writing utensil disclosed in these specifications, a clip is integrated with a knock body protruding from the rear end of an external cylinder, and an engagingly-locking protrusion is provided on the rear surface of the tip of the clip so as to engage with an engaging-lock receiving portion formed on the external cylinder to hold a writing medium at a forward position. In this knocking writing utensil, when the user attempts to allow the tip of the clip to leave the external cylinder in order to insert the clip on pocket, the engagingly-locking protrusion is disengaged from the engaging-lock receiving portion to automatically withdraw the writing medium, thereby preventing the pocket from being stained or damaged. However, since the clip moves in response to the knocking of the knock body, knocking is impossible while the clip is gripped. Thus, a problem of this writing utensil is that knocking is not easy. Furthermore, to return the writing medium to the withdrawal position, both ends of the clip must be rolled up and down, and the knocking operation of the knock body does not allow the writing medium to return to its housing position. Thus, different operations are required to move the writing medium forward and to withdraw it. Therefore, another problem of this writing utensil is that the operation is not easy. The present invention is provided in view of these problems, and an object of the invention according to claims 1 to 6 is to provide a knocking writing utensil that enables easy knocking operations and that enables the writing medium to automatically return to the withdrawal position when the clip is used. Claim 1 defines the invention and claims 2 to 6 define features which are merely optional. FR-A-2747 612 defines a pen including a knock bar, a rotator and an engaging portion of said rotator and DE-A-4 329 772 describes a pen including a clip and a knock body being the same member and a control protrusion is fixed on a back surface on the non proximal end of the clip and is guided along a control curve formed in an outer cylinder. Summary of the Invention To attain the object described above, a knocking writing utensil according to the invention comprises an external cylinder, a writing medium inserted and housed in the external cylinder so as to be moved in the axial direction, an elastic body for urging the writing medium rearward, and a knock body that is exposed from the external cylinder to be knocked, the knock body being operated to move the writing medium between a withdrawal position at which it is withdrawn into the external cylinder and a forward position at which its tip protrudes from the tip of the external cylinder. In the writing utensil, an engagement body for positioning the writing medium is provided within the external cylinder and has an engagingly-locking protrusion formed thereon. An engaging-lock receiving protruding portion including an engaging-lock receiving portion at its front end is formed on a back surface of a non-proximal end of a clip with its proximal end fixed to the external cylinder, the external cylinder having a guide hole formed therein so as to correspond to the engaging-lock receiving protruding portion of the clip, the guide hole being wider than the engaging-lock receiving protruding portion in only one lateral side of the hole relative to the engaging-lock receiving protruding portion, and the engagingly-locking protrusion of the engagement body being engaged with the engaging-lock receiving portion of the clip through the guide hole to hold the writing medium at the forward position and being disengaged from the engaging-lock receiving portion and placed behind the engaging-lock receiving protruding portion to hold the writing medium at the withdrawal position. In the writing utensil, a knock bar is disposed inside the external cylinder, said knock bar being integratedly operated with the knock body, the knock bar having a cam portion that can be engaged with the engagement body, the cam portion guiding the engagingly-locking protrusion beyond the engaging-lock receiving protruding portion from behind it to the engaging-lock receiving portion and guiding the engagingly-locking protrusion from the engaging-lock receiving portion to behind the engaging-lock receiving protruding portion in such a way as to pass by one lateral side of the engaging-lock receiving protruding portion. When the knock body is operated, the cam portion of the knock bar integratedly operated with the knock body engages with the engagement body, in order to press the engagingly-locking protrusion of the engagement body forward against the urging force of the elastic body. The cam portion of the knock bar moves the engagingly-locking protrusion beyond the engaging-lock receiving protruding portion of the clip from behind it to the engaging-lock receiving portion installed at the front end of the engaging-lock receiving protruding portion. In this manner, the engagingly-locking protrusion engages with the engaging-lock receiving portion to hold the writing medium at the forward position at which its tip protrudes from the tip of the external cylinder. In these conditions, writing is possible. The knock body is operated again to make the cam portion of the knock bar engage with the engaging body so that based on the urging force of the cam portion and elastic body, the engagingly-locking protrusion is moved from the engaging-lock receiving portion to behind the engaging-lock receiving protruding portion in such a way as to bypass the engaging-lock receiving protruding portion. Then, the engagingly-locking protrusion is disengaged from the engaging-lock receiving portion and placed behind the engaging-lock receiving protruding portion to hold the writing medium at the withdrawal position at which it is withdrawn into the external cylinder. Optionally, the cam portion of the knock bar can engage with the engagingly-locking protrusion of the engagement body and has a first cam surface that guides the engagingly-locking protrusion beyond the engaging-lock receiving protruding portion from behind it to the engaging-lock receiving portion and a second cam surface that guides the engagingly-locking protrusion from the engaging-lock receiving portion to behind the engaging-lock receiving protruding portion in such a way as to pass by one lateral side of the engaging-lock receiving protruding portion. The first and second cam surfaces of the cam portion of the knock bar reliably guide the engagingly-locking protrusion through a predetermined route to prevent malfunction. Optionally, besides the engagingly-locking protrusion, a cam receiving portion that engages with the cam portion of the knock bar can be formed on the engagement body. Since the cam receiving portion as well as the engagingly-locking protrusion are formed on the engagement body, the cam portion of the knock bar can stably guide the engagement body. A knocking writing utensil according to another aspect of the present invention comprises also an external cylinder, a writing medium inserted and housed in the external cylinder so as to be moved in the axial direction, an elastic body for urging the writing medium rearward, and a knock body that is exposed outwardly from the side of the external cylinder to be knocked, the knock body being operated to move the writing medium between a withdrawal position at which it is withdrawn into the external cylinder and a forward position at which its tip protrudes from the tip of the external cylinder. In the writing utensil, an engagement body that is coupled to the writing medium to position it is provided in the external cylinder and has an engagingly-lock protrusion formed thereon. An engaging-lock receiving protruding portion including an engaging-lock receiving portion at its front end is formed on a back surface of a non-proximal end of a clip with its proximal end fixed to the external cylinder. The external cylinder has a guide hole formed therein so as to correspond to the engaging-lock receiving protruding portion of the clip, the guide hole being wider than the engaging-lock receiving protruding portion in only one lateral side of the hole relative to the engaging-lock receiving protruding portion. But, according to said other aspect of the present invention the guide hole has, at a front end opposed to the engaging-lock receiving portion, a front-end cam surface that gradually approaches a side where the engaging-lock receiving protruding portion does not exist, towards the front end of the cam surface. The engagingly-locking protrusion is engaged with the engaging-lock receiving portion through the guide hole to hold the writing medium at the forward position and is disengaged from the engaging-lock receiving portion and placed behind the engaging-lock receiving protruding portion to hold the writing medium at the withdrawal position. The knock body is adapted to be knocked to move forward the writing medium located at the withdrawal position against the urging force of the elastic body to move the engagingly-locking protrusion beyond the engaging-lock receiving protruding portion from behind it to the engaging-lock receiving portion, and is adapted to be knocked to move forward the writing medium located at the forward position to cause the engagingly-locking protrusion to depart from the engaging-lock receiving portion and then to slide on the front-end cam surface in order to move the engagingly-locking protrusion to behind the engaging-lock receiving protruding portion in such a way as to pass by one lateral side of the engaging-lock receiving protruding portion. The knock body is operated to move forward the writing medium located at the withdrawal position, against the urging force of the elastic body in order to move the engagingly-locking protrusion of the engagement body coupled to the writing medium, beyond the engaging-lock receiving protruding portion of the clip from behind it to the engaging-lock receiving portion installed at the front end of the engaging-lock receiving protruding portion. In this manner, the engagingly-locking protrusion is engaged with the engaging-lock receiving portion to hold the writing medium at the forward position at which its tip protrudes from the tip of the external cylinder. In these conditions, writing is possible. The knock body is operated to move forward the writing medium located at the forward position to cause the engagingly-locking protrusion to depart from the engaging-lock receiving portion and then to slide on the front-end cam surface in order to move the engagingly-locking protrusion to behind the engaging-lock receiving protruding portion in such a way as to bypass the engaging-lock receiving protruding portion. In this manner, the engagingly-locking protrusion is disengaged from the engaging-lock receiving portion and placed behind the engaging-lock receiving protruding portion to hold the writing medium at the withdrawal position at which it is withdrawn into the external cylinder. The engagement body may have a slit therein for bending the engagingly-locking protrusion in the direction of the inner diameter. Upon interfering with the engaging-lock receiving protruding portion of the clip, the engagingly-locking protrusion can be bent in the direction of the inner diameter in such a way to bypass the engagingly-lock receiving protruding portion to move to the front side of the engagingly-lock receiving protruding portion. Then, the operator feels resistance through the knock body to confirm this operation, resulting in improved operability. The engaging-lock receiving protruding portion may have in its rear an inclined surface (28c) that is inclined in such a way that its height gradually decreases toward its rear end, and the engagingly-locking protrusion may have at its top an inclined surface (26c) that is inclined in such a way that its height gradually decreases toward its frond end. When the engagingly-locking protrusion interferes with the engagingly-locking receiving protruding portion of the clip, the inclined surfaces of the engaging-lock receiving protruding portion and engagingly-locking protrusion slide on each other while maintaining contact therebetween to smoothly move the engagingly-locking protrusion beyond the engaging-lock receiving protruding portion. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view showing a first embodiment of a knocking writing utensil according to this invention and showing a refill (a writing medium) at a forward position; FIG. 2 is a vertical sectional view showing the first embodiment of the knocking writing utensil according to this invention and showing the refill (a writing medium) at a withdrawal position; FIG. 3 shows a knock body and an engagement body according to the first embodiment. FIG. 3(a) is a sectional view, FIG. 3(b) is a plan view, and FIG. 3(c) is a side view; FIG. 4 shows a clip according to the first embodiment. FIG. 4(a) is a side view, FIG. 4(b) is a bottom view, and FIG. 4(c) is another view of FIG. 4(a) as seen from the direction shown by an arrow; FIG. 5 is a plan view of an external cylinder (a rear cylinder) according to the first embodiment; FIGS. 6(a) to (f) are explanatory drawings showing operations of a guide hole on the external cylinder and an engagingly-locking protrusion thereon according to the first embodiment; FIG. 7 is a plan view of a second embodiment of the knocking writing utensil according to this invention; FIG. 8 is a view of the knocking writing utensil according to this invention taken along a line 8-8 in FIG. 7; FIG. 9 shows an engagement body according to the second embodiment. FIG. 9(a) is a side view, FIG. 9(b) is a plan view, and FIG. 9(c) is a sectional view taken along line 9c-9c in FIG. 9(b); FIG. 10 shows a knock bar according to the second embodiment. FIG. 10(a) is a side view, FIG. 10(b) is a plan view, and FIG. 10(c) is a sectional view taken along line 10c-10c in FIG. 10(b); FIG. 11 shows the rear surface of a clip according to the second embodiment; FIGS. 12(a) to (f) are explanatory drawings showing operations of a guide hole on the external cylinder and an engagingly-locking protrusion thereon according to the second embodiment (left) as well as operations of a cam receiving portion and a cam portion according to the same embodiment (right); FIG. 13 is a vertical sectional view of a third embodiment of the knocking writing utensil according to this invention; FIG. 14 is a partially enlarged view of a rear portion of FIG. 13; FIG. 15 is a vertical sectional view of a fourth embodiment of the knocking writing utensil according to this invention; FIG. 16 is a view showing a guide hole in an external cylinder according to the fourth embodiment; and FIG. 17 is a perspective view showing an engagement body according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of this invention will be described below with reference to the drawings. FIGS. 1 and 2 are vertical sectional views describing a first embodiment of a knocking writing utensil according to this invention. In the illustrated embodiment, this invention is applied to a ball-point pen as a writing utensil and a writing medium comprises a refill accommodating ink. A knocking writing utensil 10 comprises an external cylinder 12 consisting of a rear cylinder 14, a front cylinder 16 screwed in the tip of the rear cylinder 14, and a tip fitting 18 screwed in the tip of the front cylinder 16. A refill 20 as a writing medium is inserted and housed in the external cylinder 12 so as to be moved in the axial direction. A spring 22 that is an elastic body is interposed between a step portion 18a formed inside the tip fitting 18 and a spring receiver 20a formed on the refill 20 in order to constantly urge the refill 20 rearward. The rear end of the refill 20 is inserted into an engagement body 26 so that the engagement body 26 moves inside the external cylinder 12 together with the refill 20. The engagement body 26 has formed on its circumferential surface an engagingly-locking protrusion 26a protruding in the direction of the outer diameter and has formed in the circumferential surface a U-shaped hole 26b that is a slit and that surrounds the engagingly-locking protrusion 26a in three directions, as shown in FIG. 3. The U-shaped hole 26b enables the engagingly-locking protrusion 26a to bend in the radially inward direction. In addition, the top of the engagingly-locking protrusion 26a comprises an inclined surface 26c the height of which gradually decreases toward its front end. The rear end of the engagement body 26 is slidably inserted into the knock bar 25. The knock bar 25 has formed on its tip a cam portion 25a that can be abutted on the engagingly-locking protrusion 26a of the engagement body 26. The cam portion 25a is shaped to be sharper toward its tip, and both sides of the cam portion 25a comprise a first cam surface 25b and a second cam surface 25c. In addition, a plurality of vertical grooves 25d extending in the axial direction are formed in the outer circumferential surface of the knock bar 25, and a vertical rib 14a is formed on the corresponding inner circumferential surface of the rear cylinder 14. Thus, the vertical grooves 25d and the vertical rib 14a are fitted together to prevent the knock bar 25 from rotating relative to the external cylinder 12. The rear end of the knock bar 25 is integrated with the knock body 24, and the knock body 24 protrudes rearward from the rear cylinder 14 so as to be exposed outwardly. However, the knock body 24 and the knock bar 25 may be separate parts from each other. A proximal end 28a of a clip 28 is fitted on the rear of the outer circumference of the external cylinder 12, while an engaging-lock receiving protruding portion 28b protruding toward the external cylinder 12 is formed on the back surface of a non-proximal end of the clip 28. As shown in FIG. 4(a), the engaging-lock receiving protruding portion 28b has formed on its rear an inclined surface 28c that is inclined in such a way that its height gradually decreases toward its rear end. In addition, as shown in FIG. 4(b), the engaging-lock receiving protruding portion 28b has at its front end a cam surface 28d that is inclined in such a way that its width gradually decreases toward its front end, and the cam surface 28d has connected to its rear end an engaging-lock receiving portion 28e that is open forward and that can accommodate the engagingly-locking protrusion 26a. A guide hole 12a is formed on the outer circumferential surface of the external cylinder 12 (the rear cylinder 14) so as to correspond to the engaging-lock receiving protruding portion 28b. As shown in FIG. 5, the guide hole 12a is wider than the engaging-lock receiving protruding portion 28b (shown by an imaginary line) in only one lateral side of the hole relative to the engaging-lock receiving protruding portion 28b. The guide hole 12a has at its rear end a cam surface 12b that gradually approaches a side where the engaging-lock receiving protruding portion 28b exists, toward the rear end of the surface 12b. The engagingly-locking protrusion 26a of the engagement body 26 penetrates the guide hole 12a. In addition, the tip of the cam portion 25a of the knock bar 25 is set to be located on an axial line passing through a neighborhood of the boundary between the engaging-lock receiving portion 28e and the cam surface 28d (see FIG. 6). The first cam surface 25b is located on the cam surface 28d side relative to the boundary, while the second cam surface 25c is located on the engaging-lock receiving portion 28e side. An operation of the knocking writing utensil configured in this manner will be described with reference to FIG. 6. While the writing utensil is not in use, the refill 20 is urged rearward by the spring 22 so as to be located at the withdrawal position at which it is entirely housed in the external cylinder 12. At this time, the engagingly-locking protrusion 26a of the engagement body 26 abuts on the guide hole 12a at the rear most end of the cam surface 12b (FIG. 6(a)) to inhibit the engagement body 26 and the refill 20 from further moving rearward. Next, when the user knocks the knock body 24 forward in order to use the refill 20, the first cam surface 25b of the cam portion 25a of the knock bar 25 abuts on the engagingly-locking protrusion 26a to push it forward (FIG. 6(b)). The engagingly-locking protrusion 26a interferes with the engaging-lock receiving protruding portion 28b of the clip 28, but can pass the engaging-lock receiving protruding portion 28b because the inclined surface 28c of the engaging-lock receiving protruding portion 28b and the inclined surface 26c of the engagingly-locking protrusion 26a slide on each other while maintaining contact therebetween and because the engagingly-locking protrusion 26a then uses its flexibility to slide into the external cylinder 12 along the inclined surface 28c. The first cam surface 25b prevents the engagingly-locking protrusion 26a from diverting in the lateral direction to escape from the engaging-lock receiving protruding portion 28b, and the engagingly-locking protrusion 26a moves forward straight in the axial direction to pass the engaging-lock receiving protruding portion 28b. After passing the engaging-lock receiving protruding portion 28b, the engagingly-locking protrusion 26a reaches the front end of the guide hole 12a (FIG. 6(c)). Then, when the user reduces the force applied to the knock body 24, the spring 22 moves the refill 20 and the engagement body 28 rearward. The engagingly-locking protrusion 26a is guided by the first cam surface 25b of the cam portion 25a of the knock bar 25 to move rearward straight in the axial direction without diverting in the lateral direction. The engagingly-locking protrusion 26a then abuts on the cam surface 28d of the engaging-lock receiving protruding portion 28b and then slides on this surface while maintaining contact with it. The engagingly-locking protrusion 26a then reaches the engaging-lock receiving portion 28e to engage with it (FIG. 6(d)). This engagement prohibits the rearward movement of the refill 20 to hold it at the forward position at which its tip protrudes from the tip of the external cylinder 12. Thus, the writing utensil is ready for use. After use, when the user knocks the knock body 24 again, the second cam surface 25c of the cam portion 25a of the knock bar 25 abuts on the engagingly-locking protrusion 26a to push it forward. This operation causes the engagingly-locking protrusion 26a to leave the engaging-lock receiving portion 28e and then to slide on the second cam surface 25c of the cam portion 25a of the knock bar 25 while maintaining contact with this surface. In this manner, the engagingly-locking protrusion 26a moves to a side laterally opposite to a side where the engaging-lock receiving protruding portion 28b exists(FIG. 6(e)). When the user stops applying force to the knock body 24, the engagingly-locking protrusion 26a moves rearward by passing through a neighborhood of the engaging-lock receiving protruding portion 28b, and then abuts on the cam surface 12b. The engagingly-locking protrusion 26a slides on the cam surface 12b while maintaining contact with it to return to the rear most end of this surface. Thus, the refill 20 returns to the withdrawal position and is housed in the external cylinder 12 (FIG. 6(f)). Since the proximal end 28a of the clip 28 is fixed to the external cylinder 12, the clip 28 does not move in response to the knocking of the knock body 24 and the knocking operation of the knock body 24 is possible despite the gripping of the clip 28, thereby improving operability. In addition, the knock body 24 is knocked in order to return the refill 20 to the withdrawal position, that is, the forward and withdrawal positions can be switched by simply knocking the knock body 24, thereby further improving operability. In addition, during the forward movement during which force is applied to the knock body 24, the engagingly-locking protrusion 26a of the engagement body 26 is forced to slide under the engaging-lock receiving protruding portion 28b of the clip 28, so the resulting resistance allows the operator to confirm this operation. On the other hand, when no force is applied to the knock body 24 being moved rearward, the engagingly-locking protrusion 26a passes through a neighborhood of the engaging-lock receiving protruding portion 28b of the clip 28. Consequently, the engagingly-locking protrusion 26a operates smoothly without being caught on something before reaching the rear most end. If the user forgets to house the refill 20 and with the refill 20 at the forward position, he or she moves the external cylinder 12 away from the non-proximal end of the clip 28 in order to put the writing utensil in a pocket, the engaging-lock receiving portion 28e and the engagingly-locking protrusion 26a are disengaged from each other to cause the refill 20 to be automatically moved rearward to the withdrawal position due to the urging force of the spring 22. This operation can prevent ink from staining the pocket. The engagingly-locking protrusion 26a protruding from the guide hole 12a in the external cylinder 12 in the direction of the outer diameter can be bent in the radially inward direction. Accordingly, in assembly, this flexibility can be used to press the engagement body 26 in from the front of the rear cylinder 14 in order to assemble it into the cylinder 14. Next, FIGS. 7 to 12 show a second embodiment of this invention. A knocking writing utensil 30 comprises an external cylinder 32 consisting of a rear cylinder 34, a front cylinder 36 screwed in the tip of the rear cylinder 34, and a tip fitting 38 screwed in the tip of the front cylinder 36. A refill 40 as a writing medium is inserted and housed in the external cylinder 32 so as to be moved in the axial direction. A spring 42 that is an elastic body is interposed between a step portion 38a formed inside the tip fitting 38 and a spring receiver 40a formed on the refill 40 in order to constantly urge the refill 40 rearward. The rear end of the refill 40 is inserted into an engagement body 46 so that the engagement body 46 moves inside the external cylinder 32 together with the refill 40. The engagement body 46 has formed on its circumferential surface an engagingly-locking protrusion 46a protruding in the direction of the outer diameter and has formed in the circumferential surface a U-shaped hole 46b that is a slit and that surrounds the engagingly-locking protrusion 46a in three directions, as shown in FIG. 9. The U-shaped hole 46b enables the engagingly-locking protrusion 46a to bend in the radially inward direction. In addition, a cam receiving portion 46d that engages with a cam portion 45a of a knock bar 45, which will be described below, is formed behind the engagingly-locking protrusion 46a of the engagement body 46 and away from the engagingly-locking protrusion 46a through approximately ±90° as seen from the circumferential direction. The cam receiving portion 46d has a first and a second cam surfaces 46d1 and 46d2 that each constitute an inclined surface and a recessed portion 46d3 formed at the intersection between the first and second cam surfaces 46d1 and 46d2. The rear end of the engagement body 46 is slidably inserted into the knock bar 45. The knock bar 45 has formed at its tip the cam portion 45a that engages with the cam receiving portion 46d of the engagement body 46, as shown in FIG. 10 in detail. The cam portion 45a has a first and a second cam surfaces 45a1 and 45a2 that each constitute an inclined surface and a top 45a3 located at the intersection between the first and second cam surfaces 45a1 and 45a2 and shaped to be sharper toward the tip. In addition, a plurality of vertical ribs 45d extending in the axial direction is formed in the outer circumferential surface of the knock bar 45, and vertical grooves 34a are formed on the corresponding inner circumferential surface of the rear cylinder 34. Thus, the vertical ribs 45d and the vertical grooves 34a are fitted together to prevent the knock bar 45 from rotating relative to the external cylinder 32. The rear end of the knock bar 45 is pressed into the knock body 44 so as to integrate the knock bar 45 with the knock body 44, and the knock body 44 protrudes rearward from the rear cylinder 34 so as to be exposed outwardly. A spring 47 is interposed between the knock body 44 and the engagement body 46 to urge them so as to space them in the axial direction. A proximal end 48a of a clip 48 is fitted on the rear of the outer circumference of the external cylinder 32. The clip 48 may consist of one piece as in the first embodiment, but according to this embodiment, consists of a clip body 49 made of metal and a plastic clip decoration 50 attached to a non-proximal end of the clip body 49. An engaging-lock receiving protruding portion 48b protruding toward the external cylinder 32 is formed on the back surface of the clip decoration 50. The engaging-lock receiving protruding portion 48b has formed in its rear an inclined surface 48c that is inclined in such a way that its height gradually decreases toward its rear end (FIG. 8). In addition, as shown in FIG. 11, the engaging-lock receiving protruding portion 48b has at its front end a cam surface 48d that is inclined in such a way that its width gradually decreases toward its front end, and the cam surface 48d has connected to its rear end an engaging-lock receiving portion 48e that is open forward and that can accommodate the engagingly-locking protrusion 46a. In addition, as shown in FIG. 11, recessed portions 50a for receiving a protruding portion 49a of the clip body 49 are formed in both sides of the rear surface of the clip decoration 50. A guide hole 32a is formed on the outer circumferential surface of the external cylinder 32 (the rear cylinder 34) so as to correspond to the engaging-lock receiving protruding portion 48b. As shown by the dotted line in FIG. 7, the guide hole 32a is wider than the engaging-lock receiving protruding portion 48b (shown by an imaginary line) in only one lateral side of the hole relative to the engaging-lock receiving protruding portion 48b. The guide hole 32a has at its rear end a cam surface 32b that gradually approaches a side where the engaging-lock receiving protruding portion 48b exists, toward the rear end of the surface 32b. The engagingly-locking protrusion 46a of the engagement body 46 penetrates the guide hole 32a. In addition, the top 45a3 of the cam portion 45a of the knock bar 45 is set to be located on the same axial line as the recessed portion 46d3 when the refill 40 is at the withdrawal position at which it is inside the external cylinder 32. An operation of the knocking writing utensil configured in this manner will be described with reference to FIG. 12. While the writing utensil is not in use, the refill 40 is urged rearward by the spring 42 so as to be located at the withdrawal position at which it is entirely housed in the external cylinder 32. At this time, the engagingly-locking protrusion 46a of the engagement body 46 abuts on the guide hole 32a at the rear most end of the cam surface 32b (FIG. 12(a)) to inhibit the engagement body 46 and the refill 40 from further moving rearward. Next, when the user knocks the knock body 44 forward in order to use the refill 40, the top 45a3 of the cam portion 45a of the knock bar 45 engages with the recessed portion 46d3 of the cam receiving portion 46d of the engagement body 46 to push the engagement body 46 forward (FIG. 12(b)). The engagingly-locking protrusion 46a of the engagement body 46 interferes with the engaging-lock receiving protruding portion 48b of the clip 48, but can pass the engaging-lock receiving protruding portion 48b because the engagingly-locking protrusion 46a slides on the inclined surface 48c of the engaging-lock receiving protruding portion 48b while maintaining contact therebetween and because the engagingly-locking protrusion 46a then uses its flexibility to slide into the external cylinder 32 along the inclined surface 48c. Since the top 45a3 of the cam portion 45a is engaged with the recessed portion 46d3 of the cam receiving portion 46d, the engagingly-locking protrusion 46a is prevented from diverting in the lateral direction to escape from the engaging-lock receiving protruding portion 48b, and moves forward straight in the axial direction to pass the engaging-lock receiving protruding portion 48b. After passing the engaging-lock receiving protruding portion 48b, the engagingly-locking protrusion 46a reaches the front end of the guide hole 32a (FIG. 12(c)). Then, when the user reduces the force applied to the knock body 44, the spring 42 moves the refill 40 and the engagement body 46 rearward. While the top 45a3 of the cam portion 45a of the knock bar 45 remains engaged with the recessed portion 46d3, the engagingly-locking protrusion 46a moves rearward straight in the axial direction without diverting in the lateral direction and abuts on the cam surface 48d of the engaging-lock receiving protruding portion 48b. When the force applied to the knock body 44 is further reduced, the recessed portion 46d3 of the engagement body 46 and the top 45a3 of the cam portion 45a are disengaged from each other to cause the engagingly-locking protrusion 46a to slide on the cam surface 48d while maintaining contact with it. The engagingly-locking protrusion 46a then reaches the engaging-lock receiving portion 48e to engage with it (FIG. 12(d)). This engagement prohibits the rearward movement of the refill 40 to hold it at the forward position at which its tip protrudes from the tip of the external cylinder 32. Thus, the writing utensil is ready for use. The knock body 44 is returned to its rearward position due to the urging force of the spring 47. After use, when the user knocks the knock body 44 again, the first cam surface 45a1 of the cam portion 45a of the knock bar 45 abuts on the first cam surface 46d1 of the cam receiving portion 46d of the engagement body 46 to push it forward. This operation causes the engagingly-locking protrusion 46a of the engagement body 46 to leave the engaging-lock receiving portion 48e and then to move to a side laterally opposite to a side where the engaging-lock receiving protruding portion 48b exists (FIG. 12(e)). When the user stops applying force to the knock body 44, the engagingly-locking protrusion 46a moves rearward by passing through a neighborhood of the engaging-lock receiving protruding portion 48b, and then abuts on the cam surface 32b. The engagingly-locking protrusion 46a slides on the cam surface 32b while maintaining contact with it to return to the rear most end of this surface (FIG. 12(f)). Thus, the refill 40 returns to the withdrawal position and is housed in the external cylinder 32. The above configuration provides effects similar to those of the first embodiment. In addition, according to the second embodiment, the cam receiving portion 46d is formed separately from the engagingly-locking protrusion 46a, so the cam portion 45a of the knock bar 45 can guide the engagement body 46 stably. Next, FIGS. 13 and 14 show a third embodiment of this invention. Although the first and second embodiments have been described in conjunction with the rear-end knocking writing utensil in which the knock body 24, 44 protrudes from the rear end of the external cylinder 12, 32, this embodiment differs from them in that it comprises a knock body on the side of an external cylinder (the knock body can be knocked in the radial direction or slidably knocked in the axial direction), that is, it is a side knock writing utensil. A side knock writing utensil 60 comprises an external cylinder 62 consisting of a front cylinder 66 screwed in the tip of the rear cylinder 34 and a tip fitting 68 screwed in the tip of the front cylinder 66. A refill 70 as a writing medium is inserted and housed in the external cylinder 62 so as to be moved in the axial direction. A spring 72 that is an elastic body is interposed between a step portion 66a formed inside the front cylinder 66 and the front end of a refill receiver 71. The rear end of the refill 70 is inserted into the refill receiver 71 in such a way that the refill receiver 71 and the refill 70 are integrated together. The spring 72 constantly urges the refill 70 and the refill receiver 71 rearward. The refill receiver 71 has formed in its front a knock receiving portion 71a the diameter of which is increased relative to the refill receiver and that has a rear end surface acting as a cam surface. In addition, a knock body 74 that can swing is attached to the circumferential surface of the front cylinder 66. When the knock body 74 is side knocked and is swung into the front cylinder 66, the cam surface of the knock receiving portion 71a is pushed forward. An engagement body 76 abuts on the rear end of the refill receiver 71 so that the refill receiver 71 and the refill 70 can be positioned by adjusting the position of the engagement body 76. As shown in the enlarged view in FIG. 14, the engagement body 76 has on its circumferential surface an engagingly-locking protrusion 76a, a U-shaped hole 76b, and a cam receiving portion 76d that are identical to the engagingly-locking protrusion 46a, the U-shaped hole 46b, and the cam receiving portion 46d according to the second embodiment. The engagingly-locking protrusion 76a can be bent in the radially inward direction. The cam receiving portion 76d also has a first and a second cam surfaces 76d1 and 76d2 each constituting an inclined surface and a recessed portion 76d3 formed at the intersection between the first and second cam surfaces 76d1 and 76d2, as in the second embodiment. The rear end of the refill receiver 71 is coupled to the knock bar 75. The knock bar 75 has formed thereon a cam portion 75a that engages with the cam receiving portion 76d of the engagement body 76 as in the cam portion 45a of the knock bar 45 in the second embodiment. The cam portion 75a has a first and a second cam surfaces 75a1 and 75a2 that each constitute an inclined surface and a top 75a3 located at the intersection between the first and second cam surfaces 75a1 and 75a2 and shaped to be sharper toward the tip. In addition, a plurality of vertical ribs 75d extending in the axial direction is formed in the outer circumferential surface of the knock bar 75, and the vertical ribs 75d are fitted in the corresponding vertical grooves 34a in the rear cylinder 34 to prevent the knock bar 75 from rotating relative to the external cylinder 62. A spring 77 is provided on the inner circumferential surface of the engagement body 76 and is interposed between the engagement body 76 and the refill receiver 71 to urge the engagement body 76 rearward relative to the refill receiver 71, in other words, toward the knock bar 75. In other words, the spring 77 serves to urge the cam receiving portion 76d of the engagement body 76 so as to abut it on the cam portion 75a. The spring 77 is selected to have a weaker spring force than the spring 72. A rear-end cap 78 is attached to the rear end of the external cylinder 62. The clip 48 is fitted in the rear of the outer circumference of the external cylinder 62. The clip 48 is the same as in the second embodiment, so its detailed description is omitted. The guide hole 62a in the outer circumferential surface of the external cylinder 62 is also the same as in the second embodiment. An operation of the side knock writing utensil configured in this manner is similar to the operation of the second embodiment. When the user knocks the knock body 74 in order to move the refill 70 forward, the knock body 74 moves the refill receiver 71 forward to move forward the knock bar 75 coupled to the refill receiver 71, thereby allowing the cam portion 75a of the knock bar 75 and the cam receiving portion 76d of the engagement body 76 to perform the same operations as shown in FIGS. 12(a) to 12(d). Thus, the engagingly-locking protrusion 76a of the engagement body 76 engages with the engaging-lock receiving portion 48e, and the engagement body 76 prohibits the refill 70 from moving rearward. As a result, the refill 70 is held at the forward position at which its tip protrudes from the tip of the external cylinder 62. After use, when the user knocks the knock body 74 again, the knock body 74 moves the refill receiver 71 forward to move forward the knock bar 75 coupled to the refill receiver 71, thereby allowing the cam portion 75a of the knock bar 75 and the cam receiving portion 76d of the engagement body 76 to perform the same operations as shown in FIGS. 12(e) to 12(f). Thus, the refill 70 returns to the withdrawal position at which its tip has retreated behind the tip of the external cylinder 62 so as to be housed in the external cylinder 62. These operations provide effects similar to those of the above embodiments. Next, FIGS. 15 to 17 show a fourth embodiment of this invention. In these figures, the same members as in the above embodiments have the same reference numerals, and their detailed description is omitted. The fourth embodiment differs from the above embodiments in that it is a side knock writing utensil and requires a smaller number of parts than the third embodiment. An engagement body 86 in a knocking writing utensil 80 according to this embodiment has an engagingly-locking protrusion 86a, a U-shaped hole 86b, and a slit 86c located 180° away from the engagingly-locking protrusion 86a in the circumferential direction. The slit 86c is used to fit the engagement body 86 on the rear end of the refill receiver 81 so that the engagement body 86 can be moved inside the external cylinder 82 integrally with the refill receiver 81 which supports the rear end of the refill 70. The knock bar 75 and the spring 77 can be omitted. In addition, as shown in FIG. 16, the guide hole 82a in the external cylinder 82 is wider than the engaging-lock receiving protruding portion 48b (shown by an imaginary line) in only one lateral side of the hole relative to the engaging-lock receiving protruding portion 48b. The guide hole 82a has formed at its rear end a rear-end cam surface 82b that gradually approaches a side where the engaging-lock receiving protruding portion 48b exists, toward the rear end of the surface 82b. In addition, the guide hole 82a has at its front end a front-end first cam surface 82c that gradually approaches a side where the engaging-lock receiving protruding portion 48b does not exist, toward the front end of the surface 82b as well as a front-end second cam surface 82d connected to the front-end first cam surface 82c. In the side knock writing utensil configured in this manner, when the user knocks the knock body 74 in order to move the refill 70 forward, the knock body 74 moves the refill receiver 81 forward to move forward the engagement body 86 coupled to the rear end of the refill receiver 81. This operation induces a cooperative operation between the engagingly-locking protrusion 86a of the engagement body 86 and the engaging-lock receiving protruding portion 48b as shown in the left half of FIGS. 12(a) to 12(d). Then, the engagingly-locking protrusion 86a moves as shown by the arrow in FIG. 16 and engages with the engaging-lock receiving portion 48e. In this manner, the refill 70 is held at the forward position at which its tip protrudes from the tip of the external cylinder 82. After use, when the user knocks the knock body 74 again, the knock body 74 moves the refill receiver 71 forward to move forward the engagement body 86 coupled to the refill receiver 71. Then, as shown by the arrow in FIG. 16, the engagingly-locking protrusion 86a of the engagement body 86 leaves the engaging-lock receiving portion 48e, reaches the front-end second cam surface 82d, slides on this surface 82d while maintaining contact with it to move to a side laterally opposite to a side with the engaging-lock receiving protruding portion 48b. When the user stops applying force to the knock body 74, the engagingly-locking protrusion 86a moves rearward by passing through a neighborhood of the engaging-lock receiving protruding portion 48b and then abuts on the rear-end cam surface 82b. The engagingly-locking protrusion 86a slides on the rear-end cam surface 82b while maintaining contact with it to return to the rear most end of this surface. Thus, the refill 70 returns to the withdrawal position and is housed in the external cylinder 82. To perform this withdrawal operation reliably, the boundary between the front-end first and second cam surfaces 82c and 82d is formed closer to the lateral side where the engaging-lock receiving protruding portion 48b exists than to the side opposite to the engaging-lock receiving portion 48e. As described above, the fourth embodiment does not only provide the effects of the above embodiments but can also reduce the number of required parts to simplify the structure. Although the above examples have been shown in conjunction with the application of this invention to a ball-point pen as a writing utensil, this invention is not limited to this aspect but is also applicable to a mechanical pencil wherein a lead delivery mechanism is used as a writing medium to allow the knock body to be operated to move the lead delivery mechanism from the withdrawal position to the forward position. This invention can also be applied to a magic marker using as a writing medium a holder that contains and holds ink or a felt core. Furthermore, although in the above embodiments, the engagement body, the refill, and the refill receiver are separate from one another, this invention is not limited to this aspect but the writing medium and the engagement body can be integrally formed as one piece. As described above, the proximal end of the clip is fixed to the external cylinder to prevent the clip from moving in response to the knocking of the knock body while enabling the knock body to be operated despite the gripping of the clip, thereby improving operability. In addition, as in typical knocking writing utensils, the writing medium can be switched between the forward and withdrawal positions by simply knocking the knock body, thereby further improving operability. Besides, if the user attempts to house the writing utensil in a pocket with the writing medium still at the forward position, then as soon as the non-proximal end of the clip is moved, the engagingly-locking protrusion and the engaging-lock receiving portion are disengaged from each other to allow the writing medium to return to the withdrawal position. This operation can prevent the writing medium from staining or damaging the pocket.

Claims: A knocking writing utensil comprising an external cylinder (12,32,62,82) having a guide hole (12a,32a,62a,82a) formed therein; a writing medium (24,40,70) housed in the external cylinder (12,32,62,82) so as to be movable in an axial direction; an elastic body (22,42,72) for urging the writing medium (24,40.70) rearwardly; a knock body (24,44,74) exposed outwardly from the external cylinder (12,32,62,82) to be knocked to move the writing medium (24,40,70) between a withdrawal position at which the writing medium (24,40,70) is withdrawn into said external cylinder (12,32,62,82) and a forward position at which a tip of said writing medium (24,40,70) protrudes from a tip of said external cylinder (12,32,62,82); a clip (28,48) with its proximal end fixed to said external cylinder (12,32,62); an engagement body (26,46,76,86) contacting to writing medium cylinder (12,32,62,82) for positioning the writing medium (24,40,70), said engagement body (26,46,76,86) including an engagingly-locking protrusion (26a,46a,76a,86a); wherein an engaging-lock receiving protruding portion (28b,48b) including an engaging-lock receiving portion (28e,48e) at its front end, is formed on a back surface of a non-proximate end of said clip (28,48), and said guide hole (12a,32a,62a,82a) is formed in the external cylinder (12,32,62,82) so as to correspond to said engaging-lock receiving protruding portion (28b,48b) of the clip (28,48), characterized in that , 1.1 the guide hole (12a,32a,62a,82a) is wider than said engaging-lock receiving protruding portion (28b,48b) in. only one lateral side of the guide hole (12a,32a,62a) relative to said engaging-lock receiving protruding portion (28b,48b) so that the engagingly-locking protrusion (26a,46a,76a) can be engaged with said engaging-lock receiving portion (28e,48e) through said guide hole (12a,32a,62a) to hold the writing medium 24,40,70) at the forward portion and can be disengaged from said engaging-lock receiving portion (28e,48e) and placed behind said engaging-lock receiving protruding portion (28b,48b) to hold the writing medium (24,40,70) at the withdrawal position and 1.2 a knock bar (25,45,75) disposed inside said external cylinder (12,32,62) so as to be integratedly operated with the knock body (24,44,74) includes a cam portion (25a,45a,75a) being engageable with said engagement body (26,46,76) so that the cam portion (25a,45a,75a) can guide the engagingly-locking protrusion (26a,46a,76a,86a) beyond said engaging-lock receiving protruding portion (28b,48b) from behind it to said engaging-lock receiving portion (28e,48e) and can guide said engagingly-locking protrusion (26a,46a,76a) from said engaging-lock receiving portion (28e,48e) to behind said engaging-lock receiving protruding portion (28b,48b) so as topass by one lateral side of said engaging-lock receiving protruding portion (28b,48b). The knocking writing utensil according to claim 1, wherein the cam portion (25a) of said knock bar (25) can engage with said engagingly-locking protrusion (26a) of said engagement body (26) and has a first cam surface (25b) that guides the engagingly-locking protrusiion (26a) beyond the engaging-lock receiving protruding portion (28b) from behind it to the engaging-lock receiving portion (28c) and a second cam surface (25c) that guides said engagingly-locking protrusion (26a) from the engaging-lock receiving portion (28a) cam surface (25c) that guides said engagingly-locking protrusion (26a) from the engaging-lock receiving portion (28a) to behind the engaging-lock receiving protruding portion (28b) in such a way as to pass by one lateral side of the engaging-lock receiving protruding portion (28b). The knocking writing utensil according to claim 1, wherein besides said engagingly-locking protrusion (26a), a cam receiving portion (46d) that engages with the cam portion (25a) of said knock bar (25) is formed on said engagement body (26). A knocking writing utensil according to claim 1, wherein instead of feature 1.2 of claim 1 the guide hole (82a) has at a front end opposed to the engaging-lock receiving portion (48e), a front-end cam surface (82d) that gradually approaches a side where the engaging-lock receiving protruding portion (48b) does not exist, towards the front end of the cam surface (82d) so that when the knock body (74) is knocked to move forward the writing medium (70) located at said withdrawal position, said engagingly-locking protrusion (86a) is caused to move from behind it to the engaging-lock receiving portion (48e) and when the knock body (74) is knocked to move forward the writing medium (70) located at said forward position, said engagingly-locking protrusion (86a) is caused to depart from said engaging-lock receiving portion (48e) and to slide on the front-end cam surface (82d) to move behind said engaging-lock receiving protruding portion (48b) so as to pass by one lateral side of said engaging-lock receiving protruding portion (48b). The knocking writing utensil according to any one of claims 1 to 4, wherein said engagement body (26) has a slit (86c) therein for bending the engagingly-locking protrusion in the direction of the inner diameter. The knocking writing utensil according to claim 5, wherein the engaging-lock receiving protruding portion has in its rear an inclined surface (28c) that is inclined in such a way that its height gradually decreases toward its rear end, and wherein the engagingly-locking protrusion has at its top an inclined surface (26c) that is inclined in such a way that its height gradually decreases toward its front end.

Inventors: KAGEYAMA HIDEHEI, NOGUCHI YOSHIO, KAGEYAMA, HIDEHEI, NOGUCHI, YOSHIO, Kageyama, Hidehei, c/o Kotobuki &amp; Co., Ltd., Noguchi, Yoshio, c/o Kotobuki &amp; Co., Ltd.
Applicants: KOTOBUKI & CO LTD, KOTOBUKI & CO., LTD.
Application year: 1999
Main classification: B43K25
IPC codes: B43K24, B43K25