The present invention relates to a knock (click) type writing instrument.

In general, a knock type writing instrument has a knock member arranged at a rear end part of a shaft barrel, a rotor arranged at a front of the knock member, a spring biasing a refill of a writing member to a rear, and outside cams comprised of cam projections provided at an inside surface of the shaft barrel. In the knock type writing instrument, a knock operation (click operation) for pressing the knock member to the front against the biasing force of the spring is performed whereby a writing state where the writing part of a pen tip sticks out from the front end of the shaft barrel and a non-writing state where the writing part is retracted inside the shaft barrel are switched. Specifically, due to the knock operation, the knock member moves to the front together with the rotor while the rotor is made to rotate by a predetermined rotational angle. In accordance with the rotation of the rotor due to the knock operation, the rotor engages or disengages with the outside cams inside the shaft barrel and the knock type writing instrument is switched between the writing state and the non-writing state.

When the knock type writing instrument is in the writing state, the rotor biased to the rear by the spring engages with the outside cams to become fixed in place. On the other hand, the knock member is not biased by the spring and is not limited by other members either. For this reason, the knock member can move slightly in the radial direction with respect to the center axis of the knock type writing instrument and in its axial direction and ends up becoming loose. Therefore, a writing operation etc. is liable to cause the knock member to hit the rotor or the shaft barrel and a sound or vibration jarring to the user to be generated.

To solve the problem of looseness of the knock member, a knock type writing instrument described in PTL 1 is known. In the knock type writing instrument described in PTL 1, stopping projections provided at the rotor (rotating cam) and stopping steps provided at the knock member (fixed cam) become engaged in the axial direction thereby reducing the looseness.

[PTL 1] Japanese Unexamined Patent Publication No.2003-305990

In the knock type writing instrument described in PTL 1, inherently, as described in PTL 1, some looseness of the knock member in the axial direction is allowed. Furthermore, looseness of the knock member in the radial direction is not considered.

The present invention has as its object the provision of a knock type writing instrument suppressing looseness of a knock member in the radial direction with respect to a rotor.

According to one aspect of the present invention, there is provided a knock type writing instrument comprising a shaft barrel, a knock member formed into a cylindrical shape and having a cam face, and a rotor arranged at the front of the knock member, which rotor having a cam receiving face cooperating with the cam face of the knock member and an insertion part able to be inserted inside of the knock member, in which knock type writing instrument, a first limit part is formed at an inside surface of the knock member and a second limit part is formed at an outside surface of the insertion part of the rotor, when a knock operation causes the cam face and the cam receiving face to cooperate to make the rotor rotate about the knock member and make the knock type writing instrument enter the writing state, the first limit part and the second limit part being configured to be aligned in the radial direction and limit movement of the knock member in the radial direction from the rotor, the first limit part and the second limit part being configured to not be aligned in the radial direction during the knock operation.

The knock type writing instrument may be configured so that when the first limit part and the second limit part are aligned in the radial direction, the first limit part and the second limit part may abut and the knock member and the rotor may be engaged in the axial direction. The first limit part and the second limit part may be projections or ribs extending in a longitudinal direction, and the first limit part may be provided in accordance with a rotational angle of the rotor due to one knock operation. The knock type writing instrument may further comprise a refill provided with a ball pen tip holding a ball at its front end, and a buffer part comprised of a viscoelastic material running through the shaft barrel from the outside to inside may be provided, and advance of the refill may be limited by abutting against the buffer part. The buffer part may be comprised of a viscoelastic material. A gripping part may be provided at the outside surface of the shaft barrel, and the buffer part may become part of the gripping part. The knock type writing instrument may have a male screw member provided with a male screw part and a tubular female screw member provided with a female screw part and able to be screwed with the male screw member, the male screw part may have a first stopping part and the female screw part may have a second stopping part, the first stopping part and a second stopping part may ride over each other when the male screw member and the female screw member are screwed together, and the first stopping part and the second stopping part may be engaged when the male screw member and the female screw member are unscrewed.

According to the aspects of the present invention, the common effect is exhibited of provision of a knock type writing instrument suppressing looseness of the knock member with respect to the rotor in the radial direction is suppressed.

• FIG. 1 is a perspective view of a first knock type writing instrument in a non-writing state.
• FIG. 2 is a vertical cross-sectional view of the knock type writing instrument of FIG. 1.
• FIG. 3 is a disassembled perspective view of the knock type writing instrument of FIG. 1.
• FIG. 4 is a perspective view of a front shaft of the knock type writing instrument of FIG. 1.
• FIG. 5 is a perspective view of a rear shaft of the knock type writing instrument of FIG. 1.
• FIG. 6 is a vertical cross-sectional view of the rear shaft of FIG. 5.
• FIG. 7 is a perspective view of an inside barrel of the knock type writing instrument of FIG. 1.
• FIG. 8 is a side view of the inside barrel of FIG. 7.
• FIG. 9 is a vertical cross-sectional view of the inside barrel of FIG. 7.
• FIG. 10 is a perspective view of a knock member of the knock type writing instrument of FIG. 1.
• FIG. 11 is a vertical cross-sectional view of the knock member of FIG. 10.
• FIG. 12 is a perspective view of a rotor of the knock type writing instrument of FIG. 1.
• FIG. 13 is a partial perspective view for explaining engagement of a front shaft and rear shaft of the knock type writing instrument of FIG. 1.
• FIG. 14 is a schematic view showing switching of the knock type writing instrument of FIG. 1 from a non-writing state to a writing state.
• FIG. 15 is a schematic view showing switching of the knock type writing instrument of FIG. 1 from the writing state to the non-writing state.
• FIG. 16 is an assembled cross-sectional view of the knock member and the rotor of the knock type writing instrument of FIG. 1.
• FIG. 17 is a cross-sectional view at a position of a line A-A of FIG. 16 corresponding to a knock type writing instrument during a knock operation.
• FIG. 18 is a cross-sectional view at a position of a line A-A of FIG. 16 corresponding to a knock type writing instrument in the writing state.
• FIG. 19 is a perspective view of a second knock type writing instrument in the non-writing state.
• FIG. 20 is a side view of the knock type writing instrument of FIG. 19.
• FIG. 21 is a vertical cross-sectional view of the knock type writing instrument of FIG. 19.
• FIG. 22 is a disassembled perspective view of the knock type writing instrument of FIG. 19.
• FIG. 23 is a vertical cross-sectional view of a front shaft of the knock type writing instrument of FIG. 19.
• FIG. 24 is a perspective view of a rear shaft of the knock type writing instrument of FIG. 19.
• FIG. 25 is a vertical cross-sectional view of the rear shaft of FIG. 24.
• FIG. 26 is a perspective view of an inside barrel of the knock type writing instrument of FIG. 19.
• FIG. 27 is a side view of the inside barrel of FIG. 26.
• FIG. 28 is a vertical cross-sectional view of the inside barrel of FIG. 26.
• FIG. 29 is a perspective view of a clip member of the knock type writing instrument of FIG. 19.
• FIG. 30 is a vertical cross-sectional view explaining attachment of the clip member of the knock type writing instrument of FIG. 19.
• FIG. 31 is a vertical cross-sectional view of the front end part of the knock type writing instrument of FIG. 19.

Below, while referring to the drawings, embodiments of the present invention will be explained in detail. Throughout the figures, corresponding component elements will be assigned common reference notations.

FIG. 1 is a perspective view of a first knock type writing instrument 1 in a non-writing state, FIG. 2 is a vertical cross-sectional view of the knock type writing instrument 1 of FIG. 1, and FIG. 3 is a disassembled perspective view of the knock type writing instrument 1 of FIG. 1. The knock type writing instrument 1 has a shaft barrel 2 provided with a front shaft 3 and a rear shaft 4 screwed with an outside surface of a rear end part of the front shaft 3, an inside barrel 5 inserted inside of the rear end part of the shaft barrel 2, a refill of a writing member arranged inside the shaft barrel 2 and provided with a writing part 6a at one end, and a spring 7 biasing the refill 6 to the rear.

In this Description, in the axial direction of the knock type writing instrument 1, the writing part 6a side is defined as the "front" side while the opposite side to the writing part 6a is defined as the "rear" side. In the explanation of each member, the "front" side and the "rear" side are defined based on the state assembled with the knock type writing instrument 1. In the knock type writing instrument 1, the state where the writing part 6a sticks out from the shaft barrel 2 due to a knock operation is called the "writing state" (not shown) and the state where the writing part 6a is retracted inside the shaft barrel 2 is referred to as the "non-writing state" (FIG. 1 and FIG. 2). The inside barrel 5 may be included in what is called the shaft barrel 2.

At the inside surface of the shaft barrel 2, i.e., the inside surface of the inside barrel 5, outside cams 20 comprising cam projections are formed. At the inside of the rear end part of the shaft barrel 2, i.e., the inside of the rear end part of the inside barrel 5, a knock member 30 is arranged. Part of the knock member 30 sticks out from the rear end part of the inside barrel 5 toward the rear. At the front of the knock member 30, the rotor 40 is arranged. At the front end face of the rotor 40, a rear end face of the refill 6 biased by the spring 7 to the rear abuts. Therefore, the rotor 40 is constantly biased to the rear by the spring 7 through the refill 6. At the side surface of the shaft barrel 2, a clip holding part 50 is provided. The clip holding part 50 is comprised of a first holding part 50a provided at the front shaft 3 and a second holding part 50b provided at the rear shaft 4. A clip member 60 is attached by the clip holding part 50 to the shaft barrel 2.

As shown in FIG. 3, the clip member 60 is formed by bending a stainless steel or other single metal wire material into a narrow ring shape. The two ends of the wire material of the clip member 60, i.e., the first end part 61 and the second end part 62, are arranged at one side closer to the rear than the center in the longitudinal direction. The first end part 61 is arranged at the front from the second end part 62. The first end part 61 and the second end part 62 are bent so as to become perpendicular to the longitudinal direction of the clip member 60.

FIG. 4 is a perspective view of a front shaft 3 of the knock type writing instrument 1 of FIG. 1. The front shaft 3 is a tubular member. At the outside surface of the rear end part of the front shaft 3, a male screw part 3a screwed with the rear shaft 4 is provided. At the starting point 3b of the male screw part 3a, i.e., the point to which the spiral thread of the male screw part 3a extends from the rear end part toward the rear, a first stopping part 8 is provided. The first stopping part 8 is a spherical shape projection of substantially the same height as the thread of the male screw part 3a. The outside surface of the front shaft 3 from the front of the male screw part 3a to the front end aperture from which the writing part 6a sticks out is covered by a gripping part 10 formed by two-color molding at the time of production of the front shaft 3. The front shaft 3 is, for example, formed from polycarbonate or ABS, PET, PBT, or other hard plastic while the gripping part 10 is formed from PTFE or polyethylene, polypropylene, or other viscoelastic material. In the assembled state of the knock type writing instrument 1, all of the exposed outside surface of the front shaft 3 is covered by the gripping part 10, therefore the user can grip any part of the front shaft 3 when writing.

FIG. 5 is a perspective view of a rear shaft 4 of the knock type writing instrument 1 of FIG. 1, while FIG. 6 is a vertical cross-sectional view of the rear shaft 4 of FIG. 5. The rear shaft 4 is a tubular member. At an inside surface of the front end part of the rear shaft 4, a female screw part 4a able to be screwed with the male screw part 3a of the front shaft 3 is provided. At the rear of the female screw part 4a, two rectangular constricted width parts 4b sticking out toward the inside in the radial direction are formed. The constricted width parts 4b are projections sticking out by uniform heights from the inside surface of the rear shaft 4. The two constricted width parts 4b are arranged at positions facing each other across the center axis of the rear shaft 4. At the rear end parts of the constricted width parts 4b, slanted surfaces 4c are provided.

At the side surface of the rear end part of the rear shaft 4, a first holding part 50a is provided. The first holding part 50a and the two constricted width parts 4b are arranged at positions exactly 90 degrees apart in the rotational direction about the center axis. The first holding part 50a has a cutaway part 51 extending from the rear end aperture of the rear shaft 4 toward the front and formed in a substantially rectangular shape, a pair of side walls 52 formed at the two sides in the circumferential direction of the cutaway part 51, a first support part 53 provided at a front end part of the cutaway part 51, and a first front wall 54 provided at the front of the first support part 53. The pair of side walls 52, the first support part 53, and the first front wall 54 are projections sticking out from the outside surface of the rear shaft 4 in the same direction. The respective front end faces thereof are formed flat. As shown in FIG. 6, the heights of the projections are formed lower in the order of the pair of side walls 52, the first front wall 54, and the first support part 53. The pair of side walls 52 are provided with cylindrical surface shapes at the outside surfaces with respect to each other. The surface of the front side of the first front wall 54 is provided in a cylindrical surface shape. Due to this, the pair of side walls 52 and the first front wall 54 are formed so as to be inscribed inside a cylinder having a center axis perpendicular to the center axis of the rear shaft 4.

FIG. 7 is a perspective view of an inside barrel 5 of the knock type writing instrument 1 of FIG. 1, FIG. 8 is a side view of the inside barrel 5 of FIG. 7, and FIG. 9 is a vertical cross-sectional view of the inside barrel 5 of FIG. 7. The inside barrel 5 is a tubular member. At the outside surface at the front of the inside barrel 5, two rectangular recessed parts 5a are formed. The recessed parts 5a are recessed parts of uniform depths from the outside surface of the inside barrel 5. Two recessed parts 5a are arranged at positions facing each other across the center axis of the inside barrel 5. At each of the rectangular recessed parts 5a, a substantially U-shape U-hole 5b comprised of a through hole running along a rear edge and two through holes extending from the two end parts of the through hole to the front is formed. Due to the U-hole 5b, inside of the recessed part 5a, an elastically deforming part 5c is defined. The elastically deforming part 5c defined by the U-hole 5b is a cantilever beam extending to the rear. At the outside surface of each of the elastically deforming parts 5c, a projecting part 5d sticking out outward in the radial direction is formed. The projecting part 5d is a spherical shape projection. The circumscribed circle of the two projecting parts 5d about the center axis is formed to become just slightly larger than the diameter of the inscribed circle of the two constricted width parts 4b of the rear shaft 4.

At the side surface of the inside barrel 5 near the rear end part, a second holding part 50b is provided. The second holding part 50b and the two elastically deforming parts 5c are arranged at positions exactly 90 degrees apart in the rotational direction about the center axis. The second holding part 50b has a base part 55 sticking out from the side surface of the inside barrel 5 outward in the radial direction and a disk shape cover part 56 provided at the front end of the base part 55. The center axis of the cover part 56 perpendicularly intersects the center axis of the inside barrel 5. At the front end of the cover part 56, a second front wall 57 extending inward in the radial direction is provided. Furthermore, at the rear part of the second front wall 57, a second support part 58 extending further inward in the radial direction than the second front wall 57 is provided. Between the base part 55 and the second support part 58, a first recessed part 59a is provided. The first recessed part 59a opens inward in the radial direction and runs laterally. Near the base part 55 at the opposite side to the first recessed part 59a across the base part 55, a second recessed part 59b is provided. The second recessed part 59b opens toward the rear and runs in the same direction as the first recessed part 59a. The first recessed part 59a and the second recessed part 59b are arranged equally separated from the center axis of the inside barrel 5.

At the inside surface of the inside barrel 5 at the rear end part, four outside cams 20 comprising cam projections are provided at equal intervals along the circumferential direction. Due to the adjoining outside cams 20, four first guide grooves 21 running in the front-rear direction are defined. Each of the outside cams 20 are comprised of a first projection part 22 and a second projection part 23 extending in the front-rear direction and arranged consecutively in the circumferential direction. The first projection part 22 and the second projection part 23 are the same in shape. The front end faces of each of the first projection part 22 and the second projection part 23 are slanted surfaces slanted by the same angles with respect to the circumferential direction. Between each first projection part 22 and second projection part 23, a second guide groove 24 extending in the front-rear direction is formed. The width of the first guide groove 21 in the circumferential direction is larger than the width of the second guide groove 24 in the circumferential direction. The depth of the first guide groove 21 and the depth of the second guide groove 24 are the same. At each outside cam 20, a limit surface 25 is provided at the rear end of the first guide groove 21 and the second guide groove 24.

FIG. 10 is a perspective view of a knock member 30 of the knock type writing instrument 1 of FIG. 1, and FIG. 11 is a vertical cross-sectional view of the knock member 30 of FIG. 10. The knock member 30 is a tubular member formed in a gentle taper shape toward the rear. At the outside surface of the knock member 30 at the front side, eight stopping projection parts 31 are provided at equal intervals along the circumferential direction. Each of the stopping projection parts 31 is configured to be arranged inside a first guide groove 21 between adjoining outside cams 20 or inside a second guide groove 24 between a first projection part 22 and a second projection part 23. Further, each of the stopping projection parts 31 is configured so as to move in a first guide groove 21 or in a second guide groove 24 in the front-rear direction by a knock operation. At the front end surface of the knock member 30, a cam face 32 is formed. The cam face 32 has eight peak parts 33 and valley parts 34. Between the peak parts 33 and the valley parts 34, slanted surfaces are formed. At the rear end part of the knock member 30, a circular crown 35 is attached.

At the inside surface of the knock member 30, eight narrow projection shape first limit parts 36 extending from near the front end part toward the rear are provided at equal intervals along the circumferential direction. Each first limit part 36 is shaped as if cutting out a side surface of a cylinder having a center axis parallel to the center axis of the knock member 30. Therefore, the horizontal cross-section of the first limit part 36, i.e., the cross-section perpendicularly intersecting the center axis, has an arc shape contour. Further, the side surface of the knock member 30 is formed by substantially the same thickness, therefore the inside surface of the knock member 30 is formed in a gentle taper toward the rear similar to the outside shape of the knock member 30. Therefore, each projection shape first limit part 36 is formed so as to gradually be relatively reduced in height toward the rear. At the front end part of each first limit part 36, a curved part 36a formed in a spherical shape is formed. At the inside surface of the knock member 30, a ring-shape annular projection 37 is provided about the center axis so as to connect the first limit parts 36.

FIG. 12 is a perspective view of a rotor 40 of the knock type writing instrument 1 of FIG. 1. The rotor 40 is a tubular member. The rotor 40 is comprised of an insertion part 41 used inserted from the front end part of the knock member 30 to the inside and centered about the same and a large diameter part 42 arranged at the front of the insertion part 41 and larger in diameter. The insertion part 41 is formed in a gentle taper shape toward the rear. At the ring shape rear end face of the large diameter part 42, a cam receiving face 43 cooperating with the cam face 32 of the knock member 30 and having a complementary shape is formed. The cam receiving face 43, like the cam face 32 of the knock member 30, has eight peak parts 44 and valley parts 45. Between the peak parts 44 and the valley parts 45, slanted surfaces are formed. At the outside surface of the large diameter part 42, four inside cams 46 comprised of projections extending in the front-rear direction are provided at equal intervals along the circumferential direction. The widths of the inside cams 46 in the circumferential direction are smaller than the widths of the first guide grooves 21 and larger than the widths of the second guide grooves 24.

At the outside surface of the insertion part 41, two narrow projection shape second limit parts 47 extending from the rear end part toward the front are provided. The two second limit parts 47 are arranged at facing positions across the center axis of the rotor 40. The horizontal cross-sections of the second limit parts 47, i.e., the cross-sections perpendicularly intersecting the center axis of the rotor 40, are approximately isosceles trapezoidal shapes. Due to the parts corresponding to the top sides of the trapezoids, flat surface shape top parts 47a are formed across the longitudinal direction of the second limit parts 47. The top parts 47a extend substantially parallel to the center axis of the rotor 40. Further, the insertion part 41 is formed in a gentle taper shaft toward the rear. Therefore, the projection shape second limit parts 47 are formed so as to relatively increase in height toward the rear. The rear end parts of the second limit parts 47 are formed with chamfered parts 47b as if cut off at a slant.

The assembly of the knock type writing instrument 1 will be explained while mainly referring to FIG. 3. First, the spring 7 is inserted from the rear end aperture of the front shaft 3, then the refill 6 is inserted. On the other hand, the knock member 30 is inserted from the front end aperture of the inside barrel 5, then the rotor 40 is inserted. Further, the second end part 62 of the clip member 60 is pressed from the rear side to make it fit together with the second recessed part 59b of the second holding part 50b of the inside barrel 5. In other words, the clearance of the second recessed part 59b opened to the rear side is formed just slightly narrower than the outside diameter of the metal wire material of the clip member 60. For this reason, the second end part 62 is pressed against the second recessed part 59b to make the second end part 62 snap fit together with the second recessed part 59b. Next, the first end part 61 of the clip member 60 is arranged at the first recessed part 59a of the second holding part 50b of the inside barrel 5. The clearance of the first recessed part 59a opened to the inside in the radial direction is formed larger than the outside diameter of the metal wire material of the clip member 60. For this reason, it is possible to easily arrange the first end part 61 at the first recessed part 59a by making the clip member 60 elastically deform. Due to this, the clip member 60 is attached to the second holding part 50b so as to surround the base part 55.

By inserting and press fitting the inside barrel 5 into which the knock member 30 and the rotor 40 are inserted and the clip member 60 is attached from the rear end aperture of the rear shaft 4, the inside barrel 5 is attached to the rear shaft 4. At this time, the base part 55 of the second holding part 50b of the inside barrel 5 is positioned in the rotational direction so as to be received inside the cutaway part 51 of the rear shaft 4. The outside diameter of the front end part of the inside barrel 5 is just slightly larger than the diameter of the inscribed circle of the constricted width parts 4b of the rear shaft 4. However, the rear end parts of the constricted width parts 4b of the rear shaft 4 are formed with slanted surfaces 4c, therefore the front end edges of the inside barrel 5 can ride over the constricted width parts 4b and the inside barrel 5 can be inserted deep.

In the state with the inside barrel 5 attached to the rear shaft 4, the constricted width parts 4b of the rear shaft 4 are held inside the recessed parts 5a of the inside barrel 5. Even if a force acts on the inside barrel 5 prompting it to pull out from the rear shaft 4, the front end edges 4d of the constricted width parts 4b of the rear shaft 4 engage with the step parts 5e at the front of the recessed parts 5a of the inside barrel 5 so the inside barrel 5 is prevented from unintentionally detaching from the rear shaft 4. Furthermore, the projecting parts 5d of the elastically deforming parts 5c abut against the constricted width parts 4b of the rear shaft 4, Due to this, the elastically deforming parts 5c elastically deform so as to curve inward in the radial direction. If, in this state, the front end aperture of the rear shaft 4 is made to face vertically downward, gravity causes the knock member 30 and the rotor 40 to move downward, but the front end edge or the front end face of the rotor 40 engages with the rear end edges 5f or rear end faces of the elastically deforming parts 5c. Therefore, when replacing the refill etc., even if the front end aperture of the rear shaft 4 detached from the front shaft 3 is made to face vertically downward, the rotor 40 will never drop off from the rear shaft 4 and the inside barrel 5.

If inserting the base part 55 of the second holding part 50b deep into the cutaway part 51 of the rear shaft 4, the first holding part 50a and the second holding part 50b fit together whereupon the clip holding part 50 is integrally formed. In other words, the base part 55 of the second holding part 50b and the clip member 60 attached to the base part 55 are arranged between the pair of side walls 52 of the first holding part 50a. Further, the first support part 53 and the first front wall 54 of the first holding part 50a, as shown in FIG. 2, respectively abut complementarily with the second support part 58 and the second front wall 57 of the second holding part 50b whereby the first end part 61 of the clip member 60 is surrounded. In other words, the first end part 61 comprising the attachment part of the clip member 60 is held between the first holding part 50a and the second holding part 50b in the radial direction. As a result, the clip member 60 is attached to the shaft barrel 2 by the clip holding part 50.

The clip holding part 50 is formed in a substantially columnar shape as a whole by the pair of side walls 52 and the first front wall 54 of the first holding part 50a and the cover part 56 and the second front wall 57 of the second holding part 50b. The clip member 60 is arranged with the substantially columnar shape clip holding part 50 running along the center axis of the knock type writing instrument 1 laterally. For this reason, the attachment parts of the clip member 60, i.e., the first end part 61 and furthermore the second end part 62, are substantially covered by the clip holding part 50. Therefore, the mounting structure, i.e., the part of the clip member 60 relating to attachment, cannot be seen from the outside, therefore it is possible to improve the design sense of the mounting structure of the clip member 60. Furthermore, in the knock type writing instrument 1, the clip member 60 can be easily disassembled by taking out the inside barrel 5 from the rear shaft 4.

FIG. 13 is a partial perspective view for explaining engagement of the front shaft 3 and rear shaft 4 of the knock type writing instrument 1 of FIG. 1. The inside barrel 5 is attached to the rear shaft 4, then the rear shaft 4 is screwed with the front shaft 3 into which the refill 6 and the spring 7 have been inserted. As explained above, the first stopping part 8 is provided at the outside surface of the rear end part of the front shaft 3, while the second stopping part 9 is provided at the inside surface of the rear shaft 4 as shown in FIG. 13. The second stopping part 9 is a projection provided near the end point of the female screw part 4a, having substantially the same height as the thread of the female screw part 4a, and formed so as to bridge a valley of the female screw part 4a.

The first stopping part 8 of the front shaft 3 and the second stopping part 9 of the rear shaft 4 are provided so as to ride over each other when the front shaft 3 and rear shaft 4 finish being screwed together. Even if vibration etc. at the time of writing by the knock type writing instrument 1 causes a rotational force to act in a direction prompting the front shaft 3 and the rear shaft 4 to disengage, the first stopping part 8 and the second stopping part 9 engage with each other and unintended unscrewing is prevented. The first stopping part 8 and the second stopping part 9 may be made any shapes of projections arranged in any way so long as the parts ride over each other and engage at the time the front shaft 3 and the rear shaft 4 are screwed together.

Note that, if left in the screwed state over a long period of time, sometimes the threads of the male screw part 3a and the female screw part 4a will deform along with creeping whereby the fastenable amount will become larger than envisioned. At this time, if the front shaft 3 is further fastened with the rear shaft 4, the starting point 3b of the male screw part 3a of the front shaft 3 is liable to abut against the second stopping part 9 of the rear shaft 4. To prevent the male screw part 3a of the front shaft 3 and the second stopping part 9 of the rear shaft 4 from abutting, when the front shaft 3 and rear shaft 4 are finished being screwed together before creep advances, the starting point 3b of the male screw part 3a of the front shaft 3 and the second stopping part 9 of the rear shaft 4 are separated by exactly a predetermined angle, in other words, the starting point 3b of the male screw part 3a of the front shaft 3 and the first stopping part 8 are separated by exactly a predetermined angle. The predetermined angle between the starting point 3b of the male screw part 3a of the front shaft 3 and the first stopping part 8 is, for example, 90 degrees.

FIG. 14 is a schematic view showing switching of the knock type writing instrument 1 of FIG. 1 from a non-writing state to a writing state. In other words, FIG. 14 is a schematic view showing the positional relationship between the outside cams 20, the knock member 30, and the rotor 40 and shows the positions of the stopping projection parts 31 of the knock member 30 and the inside cams 46 of the rotor 40 with respect to the outside cams 20 spread out in the circumferential direction. In the figure, the bottom is the front of the knock type writing instrument 1 and the top is the rear of the knock type writing instrument 1. The shapes of the limit surfaces 25 provided at the rear ends of the first guide grooves 21 and the second guide grooves 24 and the shapes of the stopping projection parts 31 of the knock member 30 are drawn simplified for convenience. The rotor 40 is given rotational force by cooperation with the cam face 32 of the knock member 30 and cam receiving face 43 of the rotor 40 and rotates about its center axis. For this reason, in FIG. 14, the rotor 40 moves from the right to the left in the figure for each knock operation.

FIG. 14(a) is a schematic view showing the non-writing state of the knock type writing instrument 1. At this time, the inside cams 46 of the rotor 40 biased to the rear by the spring 7 through the refill 6 are arranged inside the first guide grooves 21 between the outside cams 20. Therefore, in this state, the writing part 6a retracts inside the shaft barrel 2. The stopping projection parts 31 of the knock member 30 are arranged inside the first guide grooves 21 or inside the second guide grooves 24. The cam face 32 and cam receiving face 43 are arranged offset in phase.

By performing a knock operation pressing the knock member 30 to the front against the biasing force of the spring 7 from the state of FIG. 14(a), the knock member 30 and the rotor 40 are made to advance. At this time, the stopping projection parts 31 of the knock member 30 and the inside cams 46 of the rotor 40 move inside the first guide grooves 21 to the front. Further, the knock member 30 and the rotor 40 receive force components in the circumferential direction in opposite directions from each other through the slanted surfaces of the cam face 32 and cam receiving face 43, but rotation of the rotor 40 is limited by the stopping projection parts 31 arranged inside the second guide grooves 24 and the side surfaces of the first projection parts 22 and the second projection parts 23 of the outside cams 20 abutting against each other.

If the knock member 30 and the rotor 40 further advance, the rear end parts of the inside cams 46 pass the front end parts of the outside cams 20, i.e., the first projection parts 22, in the front-rear direction (FIG. 14(b)). At this time, the limit of the rotation of the rotor 40 by the outside cams 20 is released and the cam face 32 and cam receiving face 43 intermesh.

If releasing the pressing of the knock member 30 from the state where the cam face 32 and cam receiving face 43 intermesh, the knock member 30 and the rotor 40 retract by the biasing force of the spring 7. At this time, the rotor 40 receives a force component from the slanted surfaces of the outside cams 20 and rotates about the center axis. In other words, the inside cams 46 of the rotor 40 move along the slanted surfaces of the outside cams 20 until it comes into contact with the side surfaces of the front end parts of the second projection parts 23 whereupon rotation of the rotor 40 stops. The widths of the inside cams 46 are smaller than the widths of the first guide grooves 21 and larger than the widths of the second guide grooves 24, therefore the inside cams 46 cannot enter inside the second guide grooves 24. Therefore, the inside cams 46 engage with the front end faces of the first projection parts 22 whereby retraction of the rotor 40 is limited (FIG. 14(c)). As a result, the writing part 6a of the refill 6 arranged at the front of the rotor 40 sticks out from the shaft barrel 2 and the knock type writing instrument 1 enters the writing state.

FIG. 15 is a schematic view showing switching of the knock type writing instrument 1 of FIG. 1 from the writing state to a non-writing state. FIG. 15 shows the positional relationship etc. of the outside cams 20, the knock member 30, and the rotor 40 in the same way as FIG. 14.

FIG. 15(a) is a schematic view showing the writing state of the knock type writing instrument 1 and a schematic view the same as FIG. 14(c). By performing a knock operation pressing the knock member 30 to the front against the biasing force of the spring 7 from the state of FIG. 15(a), the knock member 30 and the rotor 40 are made to advance. At this time, the stopping projection parts 31 of the knock member 30 and the inside cams 46 of the rotor 40 move inside the first guide grooves 21 to the front. Further, the knock member 30 and the rotor 40 receive force components in the circumferential direction in opposite directions from each other through the slanted surfaces of the cam face 32 and cam receiving face 43, but rotation of the rotor 40 is limited by the stopping projection parts 31 arranged inside the second guide grooves 24 and the side surfaces of the first projection parts 22 and the second projection parts 23 of the outside cams 20 abutting against each other.

If the knock member 30 and the rotor 40 further advance, the rear end parts of the inside cams 46 pass the front end parts of the outside cams 20, i.e., the second projection parts 23, in the front-rear direction (FIG. 15(b)). At this time, the limit on the rotation of the rotor 40 by the outside cams 20 is released and the cam face 32 and cam receiving face 43 intermesh.

If releasing the pressing of the knock member 30 from the state where the cam face 32 and cam receiving face 43 intermesh, the knock member 30 and the rotor 40 retract by the biasing force of the spring 7. At this time, the rotor 40 receives a force component from the slanted surfaces of the outside cams 20 and rotates about the center axis. In other words, the inside cams 46 of the rotor 40 enter the first guide grooves 21 from the slanted surfaces of the outside cams 20 and move to the rear, therefore the knock member 30 and the rotor 40 retract. The retraction of the knock member 30 and the rotor 40 is limited by the stopping projection parts 31 of the knock member 30 engaging with the limit surfaces 25 provided at the rear ends of the first guide grooves 21 and the second guide grooves 24 (FIG. 15(c)). As a result, the writing part 6a of the refill 6 arranged at the front of the rotor 40 retracts inside of the shaft barrel 2 and the knock type writing instrument 1 enters the non-writing state.

FIG. 16 is an assembled cross-sectional view of the knock member 30 and the rotor 40 of the knock type writing instrument 1 of FIG. 1. While not shown in FIG. 16, as explained above, two second limit parts 47 are provided toward the front from the rear end part of the insertion part 41 of the rotor 40. The first limit parts 36 of the knock member 30 and the second limit parts 47 of the rotor 40 are basically provided so that the positions in the axial direction overlap.

The rotor 40 rotates by exactly a predetermined rotational angle with each knock operation and is repeatedly engaged and disengaged with the outside cams 20. At the inside surface of the inside barrel 5, four outside cams 20 are provided at equal intervals along the circumferential direction, therefore the rotor 40 alternately engages four times and disengages four times with respect to the outside cams 20 while rotating exactly one turn. Therefore, the predetermined rotational angle of the rotor 40 in each knock operation is specifically 45 degrees.

FIG. 17 is a cross-sectional view at a position of a line A-A of FIG. 16 corresponding to the knock type writing instrument 1 during a knock operation, while FIG. 18 is a cross-sectional view at a position of a line A-A of FIG. 16 corresponding to the knock type writing instrument 1 in a writing state. The state shown in FIG. 17 corresponds to the state shown in FIG. 14(b) and FIG. 15(b). The state shown in FIG. 18 corresponds to the state shown in FIG. 14(a), FIG. 14(c), FIG. 15(a), and FIG. 15(c).

As shown in FIG. 17, in the knock type writing instrument 1 during a knock operation, the first limit parts 36 of the knock member 30 and the second limit parts 47 of the rotor 40 do not match in the rotational direction, i.e., are not aligned in the radial direction. On the other hand, as shown in FIG. 18, in the knock type writing instrument 1 in the writing state, the first limit parts 36 of the knock member 30 and the second limit parts 47 of the rotor 40 match in the rotational direction, i.e., are aligned in the radial direction.

Here, the knock member 30 is provided with eight first limit parts 36, while the rotor 40 is provided with two second limit parts 47. The heights of the first limit parts 36 from the inside surface of the knock member 30 and the heights of the second limit parts 47 of the outside surface of the rotor 40 are set so that the outside diameter of the inscribed circle of the eight first limit parts 36 becomes equal to the outside diameter of the circumscribed circle of the two second limit parts 47 or becomes just slightly smaller than it.

Due to the first limit parts 36 and the second limit parts 47 becoming aligned in the radial direction, movement of the knock member 30 with respect to the rotor 40 in the radial direction is limited. In more detail, for example, in the knock type writing instrument 1 in the writing state, the rotor 40 is biased with respect to the outside cam 20 by the spring 7 through the refill 6 and as a result is fixed in place. On the other hand, the biasing force of the spring 7 does not act on the knock member 30, but the knock member 30 is limited in movement in the radial direction with respect to the fixed rotor 40. Therefore, the knock member 30 will not become loose with respect to the rotor 40 in the radial direction. Furthermore, due to the outside diameter of the inscribed circle of the eight first limit parts 36 being made just slightly smaller than the outside diameter of the circumscribed circle of the two second limit parts 47, the first limit parts 36 and the second limit parts 47 abut. As a result, the knock member 30 and the rotor 40 are locked or engaged and movement of the knock member 30 in the axial direction with respect to the rotor 40 is limited. Therefore, the knock member 30 will not become loose with respect to the rotor 40 in the axial direction.

Due to the first limit parts 36 of the knock member 30 having horizontal cross-sectional shapes having arc shape contours, the first limit parts 36 can smoothly slide with respect to the second limit parts 47 of the rotating rotor 40. As a result, the first limit parts 36 and the second limit parts 47 can become smoothly aligned in the radial direction. Further, due to the second limit parts 47 of the rotor 40 being provided with flat surface shape top parts 47a, the first limit parts 36 and the second limit parts 47 can be more reliably locked or engaged with the arc shape top parts of the first limit parts 36 in the state aligned in the radial direction. Furthermore, due to the front end parts of the first limit parts 36 being provided with the curved parts 36a and the rear end parts of the second limit parts 47 of the rotor 40 being provided with the chamfered parts 47b, even if the knock member 30 moves with respect to the rotor 40 in the axial direction and the front end parts of the first limit parts 36 and the rear end parts of the second limit parts 47 strike each other, they can smoothly slide.

As explained above, with one knock operation, the rotor 40 rotates by exactly 45 degrees, but the eight first limit parts 36 are also separated by exactly 45 degrees rotational angle. Therefore, the first limit parts 36 and the second limit parts 47 become aligned in the radial direction not only at the time of the writing state of the knock type writing instrument 1, but also at the time of the non-writing state. In other words, during a knock operation, as shown in FIG. 17, the first limit parts 36 are positioned between adjoining second limit parts 47, therefore the first limit parts 36 and the second limit parts 47 will not become aligned in the radial direction. Therefore, a knock operation will not be obstructed. Note that, in the non-writing state, in the knock type writing instrument 1, the knock member 30 and the rotor 40 are biased integrally by the spring 7 through the refill 6, therefore looseness of the knock member 30 with respect to the rotor 40 will not occur.

In the above-mentioned knock type writing instrument 1, there were eight first limit parts 36, but there may also be only four first limit parts 36 so that the first limit parts 36 and the second limit parts 47 become aligned only in the knock type writing instrument 1 in the writing state. In short, it is sufficient that at least the number of the first limit parts 36 be provided resulting in the knock type writing instrument 1 becoming the writing state while the rotor 40 turns one time. The first limit parts 36 are provided in accordance with the rotational angle of the rotor 40 due to one knock operation. Furthermore, the shapes and numbers of the first limit parts 36 and the second limit parts 47 may be freely set for exactly the numbers resulting in the knock type writing instrument 1 becoming the writing state while the rotor 40 turns one time so long as the knock member 30 and the rotor 40 are limited or engage.

For example, the first limit parts 36 and the second limit parts 47 were all ribs extending in the longitudinal direction, but one or both of the first limit parts 36 and the second limit parts 47 may also be projections arranged at positions where they are limited or locked when the knock type writing instrument 1 is in the writing state. The second limit parts 47 may also be at least two, preferably three or more, projections or ribs arranged symmetrically about the center axis of the rotor 40. By three or more of the second limit parts 47 being provided and three or more corresponding first limit parts 36 being limited or locked, it is possible to reliably suppress looseness of the knock member 30 with respect to the rotor 40 in all of the radial directions. Further, one or both of the inside surface of the knock member 30 and the outside surface of the insertion part 41 of the rotor 40 may be formed so as to have approximately polygonal horizontal cross-sections. In this case, the corners of the polygon may be used as the first limit parts 36 or the second limit parts 47 to limit or lock the knock member 30 and the rotor 40.

The insertion part 41 of the rotor 40 may also be provided with one or more slits extending from the rear end aperture toward the front. Due to this, the insertion part 41 can made wider or narrower in the radial direction to absorb error in production. In other words, it is possible to reliably realize the outside diameter of the inscribed circle of the eight first limit parts 36 becoming equal to the outside diameter of the circumscribed circle of the two second limit parts 47 or becoming just slightly smaller and possible to reliably suppress looseness of the knock member 30 with respect to the rotor 40.

FIG. 19 is a perspective view of a second knock type writing instrument 100 in the non-writing state, FIG. 20 is a side view of the knock type writing instrument 100 of FIG. 19, FIG. 21 is a vertical cross-sectional view of the knock type writing instrument 100 of FIG. 19, and FIG. 22 is a disassembled perspective view of the knock type writing instrument 100 of FIG. 19. As explained above, throughout the drawings, corresponding component elements are assigned common reference notations. The second knock type writing instrument 100, compared with the first knock type writing instrument 1, has the same refill 6, spring 7, outside cams 20, knock member 30, and rotor 40, therefore the explanations of these members are omitted.

The knock type writing instrument 100 has a shaft barrel 102 provided with a front shaft 103 and a rear shaft 104 screwed with the outside surface of the rear end part of the front shaft 103, an inside barrel 105 inserted inside of the rear end part of the shaft barrel 102, a refill 6 comprising the writing member arranged inside of the shaft barrel 102 and provided with a writing part 6a at one end, and a spring 7 biasing the refill 6 to the rear. The inside barrel 105 is included in what is referred to as the shaft barrel 102.

At the inside surface of the shaft barrel 102, i.e., the inside surface of the inside barrel 105, outside cams 20 comprising cam projections are formed. At the inside part of the rear end part of the shaft barrel 102, i.e., the inside part of the rear end part of the inside barrel 105, a knock member 30 is arranged. Part of the knock member 30 sticks out to the rear from the rear end part of the inside barrel 105. At the front of the knock member 30, a rotor 40 is arranged. At the front end surface of the rotor 40, the rear end face of the refill 6 biased to the rear by the spring 7 abuts. Therefore, the rotor 40 is constantly biased to the rear by the spring 7 through the refill 6. At the side surface of the shaft barrel 102, a clip holding part 150 is provided. The clip holding part 150 is comprised of a first holding part 150a provided at the front shaft 103 and a second holding part 150b provided at the rear shaft 104. The clip member 160 is attached by the clip holding part 150 to the shaft barrel 102.

FIG. 23 is a vertical cross-sectional view of a front shaft 103 of the knock type writing instrument 100 of FIG. 19. The front shaft 103 is a tubular member. At the outside surface of the rear end part of the front shaft 103, a male screw part 103a screwed with the rear shaft 104 is provided. The outside surface of the front shaft 103 from the front of the male screw part 103a to the front end aperture from which the writing part 6a sticks out is covered by a gripping part 110 formed by two-color molding at the time of production of the front shaft 3. In the assembled state of the knock type writing instrument 100, since all of the exposed outside surface of the front shaft 103 is covered by the gripping part 110, the user can grip any part of the front shaft 103 when writing. The writing part 110 is formed from a material similar to the gripping part 10 of the above-mentioned first knock type writing instrument 1.

At the inside surface of the front end part of the front shaft 103, a ring shape support surface 103c facing the rear is provided. At the rear of the support surface 103c, four first ribs 103d and two second ribs 103e facing inward in the radial direction and extending in the front-rear direction are provided. The two second ribs 103e are arranged at positions facing each other across the center axis of the front shaft 103. The four first ribs 103d are divided into two groups and are arranged at equal intervals between the two second ribs 103e. The four first ribs 103d and two second ribs 103e are arranged at equal intervals along the circumferential direction. At the side surface of the front shaft 103 at the rear of the four first ribs 103d, a rectangular through hole 103f is formed. When forming the gripping part 110 after forming the front shaft 103 in two-color molding, the plastic material of the gripping part 110 passes through the through hole 103f to enter the inside of the front shaft 103 whereby a projection shape buffer part 111 is formed. In other words, the buffer part 111 is comprised of part of the gripping part 110. The buffer part 111 is formed integrally with the first ribs 103d and has a buffer surface 112 slanted toward the front of the front shaft 103.

FIG. 24 is a perspective view of a rear shaft 104 of the knock type writing instrument 100 of FIG. 19, while FIG. 25 is a vertical cross-sectional view of the rear shaft 104 of FIG. 24. The rear shaft 104 is a tubular member. At the inside surface of the front end part of the rear shaft 104, a female screw part 104a able to be screwed with the male screw part 103a of the front shaft 103 is provided. Note that, at the starting point of the male screw part 103a of the front shaft 103, i.e., the point to which the spiral thread of the male screw part 103a extends from the rear end part toward the rear, while not shown, a first stopping part similar to the first knock type writing instrument 1 is provided. On the other hand, at the female screw part 104a of the rear shaft 104, while not shown, a second stopping part similar to the first knock type writing instrument 1 is provided. In the second knock type writing instrument 100 as well, in the same way as the first knock type writing instrument 1, unintended unscrewing is prevented by engagement of the first stopping part and the second stopping part.

At the side surface of the rear end part of the rear shaft 104, a first holding part 150a is provided. The first holding part 150a has a first cutaway part 151a extending from the rear end aperture of the rear shaft 104 toward the front and formed in a substantially rectangular shape and a columnar shape columnar part 152 provided so as to straddle the first cutaway part 151a and having a center axis perpendicular to the center axis of the rear shaft 104. At the base of the columnar part 152, a first support part 153 partially cut away by the first cutaway part 151a and facing inward in the radial direction is provided. The front end of the columnar part 152 is provided flat in a circular shape. At a side surface of the columnar part 152, an insertion hole 154 with a rectangular cross-section extending in parallel with the center axis of the rear shaft 104 is defined. The insertion hole 154 communicates with the first cutaway part 151a.

FIG. 26 is a perspective view of an inside barrel 105 of the knock type writing instrument 100 of FIG. 19, FIG. 27 is a side view of the inside barrel 105 of FIG. 26, and FIG. 28 is a vertical cross-sectional view of the inside barrel 105 of FIG. 26. The inside barrel 105 is a tubular member. At the inside surface of the rear end part of the inside barrel 105, the above-mentioned outside cams 20 are provided.

At a side surface of the vicinity of the rear end part of the inside barrel 105, a second holding part 150b is provided. The second holding part 150b has a base part 155 sticking out from a side surface of the inside barrel 105 to the outside in the radial direction. A substantially rectangular second cutaway part 151b is formed so as to extend from the front end aperture of the inside barrel 105 toward the rear up to the base part 155. At the rear side of the base part 155, a rear wall 157 is provided. The surface of the rear wall 157, as stated later, is formed in a cylindrical shape so as to become integral with the columnar shape columnar part 152 of the rear shaft 104 in the state attached to the rear shaft 104. At the front side of the base part 155, in order from the front end, a second support part 158 facing outward in the radial direction and a recessed part 159 obliquely extending from the rear of the second support part 158 continuously toward the outside in the radial direction are provided. At the front end of the base part 155 in the radial direction, an end part 155a is provided.

FIG. 29 is a perspective view of a clip member 160 of the knock type writing instrument 100 of FIG. 19. In FIG. 29, "right" is the rear side of the knock type writing instrument 100. The clip member 160 is formed by stamping a stainless steel or other metal sheet member using press working etc. or bending it. Therefore, the clip member 160 is a sheet member overall. Specifically, the clip member 160 has an attachment part 161 of a step shape formed so as to be branched from the clip member 160. The attachment part 161 is formed simultaneously as the formation of the first aperture 162 further to the front and the second aperture 163 further to the rear. Due to this, a clip member 160 comprised of an integral sheet material of substantially the same width as a whole is defined. The front end of the clip member 160 is bent outward in the radial direction. Using the projecting part 164 formed due to this, an object is gripped with the rear shaft 104. The attachment part 161 has a curved part 165 curved in an arc shape from the rear end of the first aperture 162, a clamped part 166 bent about 90 degrees from the curved part 165 and extending to the front, and a front end part 167 bent about 90 degrees from the clamped part 166 and extending inward in the radial direction.

FIG. 30 is a vertical cross-sectional view explaining attachment of the clip member 160 of the knock type writing instrument 100 of FIG. 19. First, as shown in FIG. 30(a), the clip member 160 is arranged on the base part 155 of the second holding part 150b of the inside barrel 105. Specifically, the clamped part 166 of the clip member 160 is arranged at the second support part 158 and the front end part 167 of the clip member 160 is arranged at the rear end part of the second cutaway part 151b, in other words, the front end part of the base part 155. Alternatively, the rear part of the curved part 165 of the clip member 160 is arranged at the end part 155a of the base part 155 and the front part of the curved part 165 of the clip member 160 is arranged at the recessed part 159.

Next, as shown in FIG. 30(b), the base part 155 of the second holding part 150b of the inside barrel 105 is positioned in the rotational direction so that the base part 155 is received inside the first cutaway part 151a of the rear shaft 104 and the front end of the inside barrel 105 is inserted inside of the rear end part of the rear shaft 104. At this time, the front end of the clip member 160 is inserted in the insertion hole 154 of first holding part 150a of the rear shaft 104. Specifically, the rear end part makes the clip member 160 move to the inside in the radial direction and makes the front end part of the clip member 160 move outside in the radial direction about the end part 155a of the base part 155. Due to this, the front end of the clip member 160 can be inserted into the insertion hole 154.

Next, as shown in FIG. 30(c), the inside barrel 105 is further inserted and press fit together with the clip member 160 in the rear shaft 104. Due to this, the first holding part 150a and the second holding part 150b are fit together and the clip holding part 150 is formed. In other words, the base part 155 of the second holding part 150b and the clip member 160 attached to the base part 155 are arranged inside the columnar part 152 of the first holding part 150a. Further, the clamped part 166 of the clip member 160 is held in the radial direction between the first support part 153 of the first holding part 150a and the second support part 158 of the second holding part 150b. In other words, the attachment part 161 of the clip member 160 is held in the radial direction between the rear shaft 104 and the inside barrel 105. As a result, the clip member 160 is attached to the shaft barrel 102 by the clip holding part 150 formed integrally by the first holding part 150a and the second holding part 150b.

The clip holding part 150 is formed in a substantially columnar shape overall by the columnar part 152 of the first holding part 150a and the rear wall 157 of the second holding part 150b. The clip member 160 is arranged so that the substantially columnar shape clip holding part 150 runs through the knock type writing instrument 100 along the center axis from the side. For this reason, the attachment part of the clip member 160, i.e., the clamped part 166, is substantially concealed by the substantially columnar shape clip holding part 150. Therefore, as shown in FIG. 19 and FIG. 20, it is not possible to see the mounting structure, i.e., the part of the clip member 160 relating to mounting, from the outside, therefore it is possible to improve the design sense of the mounting structure of the clip member 160. Further, in the mounting structure, there is little unnecessary clearance, therefore dust etc. is prevented from entering the inside of the mounting structure. Furthermore, in the knock type writing instrument 100, the clip member 160 has no connecting part press fit or fit together with the rear shaft 104 or the inside barrel 105, therefore by detaching the inside barrel 105 from the rear shaft 104, it is possible to more easily disassemble the clip member 160. As a result, the rear shaft 104, inside barrel 105, and clip member 160 can be easily recycled or reused.

In the clip member 160, due to the shape of the attachment part 161, in particular the shape of the curved part 165, the front end part of the clip member 160 is biased inward in the radial direction. For this reason, an object can be gripped between the projecting part 164 of the clip member 160 and the outside surface of the shaft barrel 102, specifically the outside surface of the rear shaft 104. If releasing the grip, the rear end part of the clip member 160 is pressed inside in the radial direction and makes the attachment part 161 elastically deform about the end part 155a of the base part 155. Due to this, the front end part of the clip member 160 can move to the outside in the radial direction and release the grip. By the clip holding part 150 being provided with an insertion hole 154 of a sufficient size, swing of the clip member 160 is not obstructed.

FIG. 31 is a vertical cross-sectional view of the front end part of the knock type writing instrument 100 of FIG. 19. The refill 6 has the above-mentioned writing part 6a, an ink holding tube 6b for holding the ink to be supplied to the writing part 6a, and a connecting part 6c connecting the writing part 6a and the ink holding tube 6b. The writing part 6a is a ball pen tip holding a ball at its front end. The front end part of the spring 7 is supported by the support surface 103c of the front shaft 103, while the rear end part of the spring 7 is supported by the front end face of the flange part 6d provided at the connecting part 6c and sticking out outside in the radial direction. Due to this, the refill 6 is biased by the spring 7 to the rear. The spring 7 is surrounded by the first ribs 103d and the second ribs 103e. Due to this, bending in the radial direction is limited.

For example, if the knock type writing instrument 100 is mistakenly dropped on the floor from the rear end part side, i.e., the knock member 30 side, the impact and recoil at the time of dropping cause the refill 6 to relatively rapidly move to the front inside the shaft barrel 102. Movement of the refill 6 is limited by the flange part 6d of the connecting part 6c striking the buffer surface 112 of the buffer part 111. The buffer part 111 is formed by a viscoelastic material softer compared with the front shaft 103, therefore it is possible to ease the impact at the time of striking the refill 6. If there were no buffer part 111, the refill 6 would strike the inside surface of the front shaft 103 made of hard plastic. As a result, the impact would not be sufficiently eased and the ball held at the tip of the writing part 6a would be liable to end up popping out due to the inertial force. By the impact of the refill 6 being eased by striking the buffer surface 112, popping out of the ball can be prevented and other damage to the refill 6 can be reduced.

The buffer part 111 may be any shape and position so long as running through the shaft barrel 102 from the outside to the inside and easing impact to the refill 6. For example, in the knock type writing instrument 100, the flange part 6d of the connecting part 6c was designed to strike the buffer part 111, but it is also possible to provide a through hole near the front end aperture of the front shaft 103 and provide a corresponding buffer part in two-color molding. In this case, not the connecting part 6c of the refill 6, but the writing part 6a strikes the buffer part whereby impact is eased. Further, the buffer part may also be provided not by two-color molding but by running another member through the shaft barrel 102 from the outside to the inside. The configuration of the buffer part 111 for easing impact of the refill 6 in the second knock type writing instrument 100 may also be applied to the first knock type writing instrument 1.

The refill 6 may also be another type of writing member such as one for a marking pen, touch pen, eraser pen, etc. in addition to a ball pen type. Further, part or all of the knock member 30 including the crown 35 may be made an eraser part for erasing writing by the knock type writing instrument.

The refill 6 may also be a ball pen type in which a thermochromic ink is contained. Here, a "thermochromic ink" means an ink having the property of maintaining a predetermined color (first color) at ordinary temperature (for example, 25°C), changing to another color (second color) if made to rise in temperature to a predetermined temperature (for example, 60°C), then if made to cool to a predetermined temperature (for example, -5°C), again returning to the original color (first color). In a thermochromic type writing instrument using a thermochromic ink, making the second color a colorless one and raising the temperature of lines drawn by the first color (for example, red) to make them colorless will be referred to here as "erasure". Therefore, a writing surface etc. on which lines are drawn may be rubbed by an erasing part comprised of a friction member to generate heat of friction and thereby change the lines to colorless ones, i.e., erase them. Note that, only naturally, the second color may also be another color rather than colorless.

As the writing instrument, a knock type writing instrument was used as an example in the above explanation, but configurations or structures common between knock type writing instruments and other writing instruments, for example, cap type writing instruments and multicore type type writing instruments, for example, the structure of the first stopping part of the male screw part and the structure of the second stopping part of the female screw part or the mounting structure of the clip member, can be similarly applied to other writing instruments.

For example, regarding the structure of the first stopping part of the male screw part and the second stopping part of the female screw part, the male screw member and the female screw member can be freely selected so long as having a male screw member provided with a male screw part and a tubular female screw member provided with a female screw part able to be screwed with the male screw member, the male screw part having a first stopping part and the female screw part having a second stopping part, and the first stopping part and the second stopping part riding over each over when the male screw member and the female screw member are screwed together and the first stopping part and the second stopping part being engaged when the male screw member and the female screw member are unscrewed. For example, the male screw member and the female screw member may also be a tip member and a front shaft screwed with the rear end part of the tip member in addition to the above-mentioned front shaft 3 and rear shaft 4 and may also be a cap and a crown screwed with the rear end part of the cap.

Further, regarding the mounting structure of the clip member, the first member and the second member can be freely selected so long as there are provided a tubular first member having a first holding part, and a second member having a second holding part and being able to be inserted inside of the rear end part of the first member to be fit together with the first member in a detachable manner, and a clip member having an attachment part, the attachment part of the clip member being held between the first holding part and the second holding part in the radial direction and the clip member being attached to the first member. For example, the first member and the second member may also be a cap and a crown fitting together with a rear end part of the cap in addition to the above-mentioned rear shaft 104 and inside barrel 105.

In the above-mentioned knock type writing instrument 100, the first holding part 150a and the second holding part 150b fit together to form a clip holding part 150 of a cylindrical shape overall. Considering the design sense, the first holding part and the second holding part may also be configured to form a clip holding part of a polygonal columnar shape, for example, a hexagonal columnar shape, in addition to a circular columnar shape. Further, the attachment part may be made any shape in addition to the above-mentioned step shape so long as one able to hold an object between the first holding part and the second holding part in the radial direction. For example, the attachment part may be made a simple arc shape.

• 1 knock type writing instrument
• 2 shaft barrel
• 3 front shaft
• 4 rear shaft
• 5 inside barrel
• 20 outside cam
• 30 knock member
• 31 stopping projection part
• 36 first limit part
• 40 rotor
• 41 insertion part
• 47 second limit part
• 100 knock type writing instrument
• 102 shaft barrel
• 103 front shaft
• 104 rear shaft
• 105 inside barrel
• 150 clip holding part
• 150a first holding part
• 150b second holding part
• 160 clip member
• 161 attachment part