Knock-type writing implement

Abstract

A knock-type writing implement 1 includes a shaft tube 2, a knock member 30 which is formed in a cylindrical shape and which has a cam surface, and a rotor 40 which is disposed in front of the knock member and which has a cam receiving surface that cooperates with the cam surface of the knock member and an insertion portion 41 that can be inserted into the knock member, wherein: first restricting portions 36 are formed on an inner surface of the knock member, and second restricting portions 47 are formed on an outer surface of the insertion portion of the rotor; the configuration is such that, when the cam surface and the cam receiving surface cooperate with one other to rotate the rotor relative to the knock member by means of a knock operation, thereby causing the knock-type writing implement to adopt a writing state, the first restricting portions 36 and the second restricting portions 47 are aligned in the radial direction, thereby restricting the movement of the knock member in the radial direction with respect to the rotor; and the configuration is such that the first restricting portions 36 and the second restricting portions 47 are not aligned in the radial direction during the knock operation.

Description

Knock-type writing implement

[0001] The present invention relates to a knock-type writing instrument.

[0002] Generally, a knock-type writing instrument has a knock member disposed at the rear end of the barrel, a rotor disposed in front of the knock member, a spring that biases the refill, which is the writing body, backward, and an external cam, which is a cam protrusion, disposed on the inner surface of the barrel. In a knock-type writing instrument, by performing a knock operation that presses the knock member forward against the biasing force of the spring, the writing instrument is switched between a writing state in which the writing part, which is the pen tip, protrudes from the tip of the barrel and a non-writing state in which the writing part is retracted into the barrel. Specifically, the knock operation causes the knock member to move forward together with the rotor, rotating the rotor by a predetermined rotation angle. Depending on the rotation of the rotor caused by the knock operation, the rotor engages or disengages with the external cam inside the barrel, thereby switching the knock-type writing instrument between a writing state and a non-writing state.

[0003] When the knock-type writing instrument is in the writing state, the rotor, which is biased backward by the spring, engages with the outer cam and is fixed. Meanwhile, the knock member is not biased by the spring and is not restricted by any other components. Therefore, the knock member can move slightly radially and axially about the central axis of the knock-type writing instrument, causing it to rattle. Therefore, there is a risk that the knock member will hit the rotor or barrel during writing, resulting in unpleasant noise and vibration for the user.

[0004] To solve the problem of rattle of the knock member, a knock-type writing instrument is known, as described in Patent Document 1. In the knock-type writing instrument described in Patent Document 1, a locking protrusion provided on a rotor (rotating cam) and a locking step provided on a knock member (fixed cam) are axially locked together to reduce rattle.

[0005] Japanese Patent Application Laid-Open No. 2003-305990

[0006] In the knock-type writing instrument described in Patent Document 1, as described in Patent Document 1, slight axial rattle of the knock member is permitted, and furthermore, radial rattle of the knock member is not taken into consideration.

[0007] An object of the present invention is to provide a knock-type writing instrument in which radial rattle of the knock member relative to the rotor is suppressed.

[0008] According to one aspect of the present invention, there is provided a knock-type writing instrument comprising a barrel, a knock member formed cylindrically and having a cam surface, and a rotor arranged in front of the knock member, the rotor having a cam receiving surface that cooperates with the cam surface of the knock member and an insertion portion that can be inserted into the knock member, wherein a first regulating portion is formed on the inner surface of the knock member and a second regulating portion is formed on the outer surface of the insertion portion of the rotor, and when a knock operation causes the cam surface and the cam receiving surface to cooperate to rotate the rotor relative to the knock member and the knock-type writing instrument is in a writing state, the first regulating portion and the second regulating portion are aligned radially to regulate radial movement of the knock member relative to the rotor, and the first regulating portion and the second regulating portion are configured not to be aligned radially during the knock operation.

[0009] The pen may be configured such that when the first and second restricting portions are aligned in the radial direction, the first and second restricting portions come into contact with each other, locking the knock member and the rotor in the axial direction. The first and second restricting portions may be protrusions or ribs extending in the longitudinal direction. The first restricting portion may be provided according to the rotation angle of the rotor resulting from a single knock operation. The pen may further include a refill having a ballpoint pen tip that holds a ball at its tip, and a buffer portion that penetrates from the outside to the inside of the barrel, so that the forward movement of the refill is restricted by contact with the buffer portion; the buffer portion may be made of a viscoelastic material. A grip portion may be provided on the outer surface of the barrel, and the buffer portion may be a part of the grip portion. The screw thread may have a male threaded member having a male thread portion, and a tubular female threaded member having a female thread portion and capable of being threaded with the male threaded member, wherein the male threaded portion has a first locking portion and the female threaded portion has a second locking portion, and when the male threaded member and the female threaded member are threaded together, the first locking portion and the second locking portion climb over each other, so that when the male threaded member and the female threaded member are unthreaded from each other, the first locking portion and the second locking portion lock together.

[0010] According to the aspects of the present invention, a common effect is achieved in that a knock-type writing instrument is provided in which radial rattle of the knock member relative to the rotor is suppressed.

[0011] 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 an exploded perspective view of the knock-type writing instrument of FIG. 1. FIG. 4 is a perspective view of the front barrel of the knock-type writing instrument of FIG. 1. FIG. 5 is a perspective view of the rear barrel of the knock-type writing instrument of FIG. 1. FIG. 6 is a vertical cross-sectional view of the rear barrel of FIG. 5. FIG. 7 is a perspective view of the inner barrel of the knock-type writing instrument of FIG. 1. FIG. 8 is a side view of the inner barrel of FIG. 7. FIG. 9 is a vertical cross-sectional view of the inner barrel of FIG. 7. FIG. 10 is a perspective view of the 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 the rotor of the knock-type writing instrument of FIG. 1. FIG. 13 is a partial perspective view illustrating the fitting of the front barrel and rear barrel of the knock-type writing instrument of FIG. 1. FIG. 14 is a schematic diagram showing the switching of the knock type writing instrument of FIG. 1 from a non-writing state to a writing state. FIG. 15 is a schematic diagram showing the switching of the knock type writing instrument of FIG. 1 from a writing state to a non-writing state. FIG. 16 is an assembled cross-sectional view of the knock member and rotor of the knock type writing instrument of FIG. 1. FIG. 17 is a cross-sectional view taken along line A-A in FIG. 16, corresponding to the knock type writing instrument during a knock operation. FIG. 18 is a cross-sectional view taken along line A-A in FIG. 16, corresponding to the knock type writing instrument in a writing state. FIG. 19 is a perspective view of a second knock type writing instrument in a 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 an exploded perspective view of the knock type writing instrument of FIG. 19. FIG. 23 is a vertical cross-sectional view of the front barrel of the knock type writing instrument of FIG. 19. Figure 24 is a perspective view of the rear barrel of the knock-type writing instrument of Figure 19. Figure 25 is a vertical cross-sectional view of the rear barrel of Figure 24. Figure 26 is a perspective view of the inner barrel of the knock-type writing instrument of Figure 19. Figure 27 is a side view of the inner barrel of Figure 26. Figure 28 is a vertical cross-sectional view of the inner barrel of Figure 26. Figure 29 is a perspective view of the clip member of the knock-type writing instrument of Figure 19. Figure 30 is a vertical cross-sectional view explaining the attachment of the clip member of the knock-type writing instrument of Figure 19. Figure 31 is a vertical cross-sectional view of the front end part of the knock-type writing instrument of Figure 19.

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Corresponding components throughout the drawings are designated by common reference numerals.

[0013] Fig. 1 is a perspective view of a first knock-type writing instrument 1 in a non-writing state, Fig. 2 is a longitudinal cross-sectional view of the knock-type writing instrument 1 of Fig. 1, and Fig. 3 is an exploded perspective view of the knock-type writing instrument 1 of Fig. 1. The knock-type writing instrument 1 has a barrel 2 equipped with a front barrel 3 and a rear barrel 4 that screws onto the outer surface of the rear end of the front barrel 3, an inner barrel 5 inserted inside the rear end of the barrel 2, a refill 6 that is a writing body disposed inside the barrel 2 and equipped with a writing portion 6a at one end, and a spring 7 that urges the refill 6 rearward.

[0014] In this specification, the side of the writing part 6a in the axial direction of the knock-type writing instrument 1 is defined as the "front" side, and the side opposite the writing part 6a is defined as the "rear" side. In the description of each component, the "front" side and "rear" side are defined based on the state in which the knock-type writing instrument 1 is assembled. In the knock-type writing instrument 1, the state in which the writing part 6a protrudes from the barrel 2 due to a knock operation is referred to as the writing state (not shown), and the state in which the writing part 6a is retracted into the barrel 2 is referred to as the non-writing state (FIGS. 1 and 2). The barrel 2 may be referred to as including the inner barrel 5.

[0015] An outer cam 20, which is a cam projection, is formed on the inner surface of the barrel 2, i.e., the inner surface of the inner barrel 5. A knock member 30 is disposed inside the rear end of the barrel 2, i.e., inside the rear end of the inner barrel 5. A portion of the knock member 30 protrudes rearward from the rear end of the inner barrel 5. A rotor 40 is disposed in front of the knock member 30. The rear end face of the refill 6, which is biased rearward by the spring 7, abuts against the front end face of the rotor 40. Therefore, the rotor 40 is constantly biased rearward by the spring 7 via the refill 6. A clip holder 50 is provided on the side of the barrel 2. The clip holder 50 consists of a first holder 50a provided on the front axle 3 and a second holder 50b provided on the rear axle 4. The clip member 60 is attached to the barrel 2 by the clip holder 50.

[0016] As shown in Figure 3, the clip member 60 is formed by bending a single metal wire such as stainless steel into a long, thin ring. Each of the ends of the wire of the clip member 60, i.e., a first end 61 and a second end 62, is located on one side rearward of the longitudinal center. The first end 61 is located forward of the second end 62. The first end 61 and the second end 62 are bent perpendicular to the longitudinal direction of the clip member 60.

[0017] FIG. 4 is a perspective view of the front barrel 3 of the knock-type writing instrument 1 of FIG. 1. The front barrel 3 is a cylindrical member. The outer surface of the rear end of the front barrel 3 is provided with a male thread 3a that threadably engages with the rear barrel 4. A first locking portion 8 is provided at the start point 3b of the male thread 3a, i.e., at the end of the spiral path of the male thread 3a extending rearward from the rear end. The first locking portion 8 is a spherical protrusion with approximately the same height as the threads of the male thread 3a. The outer surface of the front barrel 3, from the front of the male thread 3a to the front-end opening from which the writing tip 6a protrudes, is covered by a handle 10 formed by two-color molding during the manufacture of the front barrel 3. The front barrel 3 is formed from a hard plastic such as polycarbonate, ABS, PET, or PBT, and the handle 10 is formed from a viscoelastic material such as PTFE, polyethylene, or polypropylene. When the knock-type writing instrument 1 is assembled, the entire exposed outer surface of the front shaft 3 is covered by the grip portion 10, so the user can grip any part of the front shaft 3 when writing.

[0018] Figure 5 is a perspective view of the rear barrel 4 of the knock-type writing instrument 1 of Figure 1, and Figure 6 is a longitudinal cross-sectional view of the rear barrel 4 of Figure 5. The rear barrel 4 is a cylindrical member. The inner surface of the front end of the rear barrel 4 is provided with a female threaded portion 4a that can be threadedly engaged with the male threaded portion 3a of the front barrel 3. Two rectangular reduced diameter portions 4b that protrude radially inward are formed behind the female threaded portion 4a. The reduced diameter portions 4b are protrusions that protrude at a uniform height from the inner surface of the rear barrel 4. The two reduced diameter portions 4b are positioned opposite each other across the central axis of the rear barrel 4. An inclined surface 4c is provided at the rear end of the reduced diameter portion 4b.

[0019] A first retaining portion 50a is provided on the side surface of the rear end of the rear axle 4. The first retaining portion 50a and each of the two reduced-diameter portions 4b are positioned at positions offset by 90 degrees in the rotational direction about the central axis. The first retaining portion 50a has a generally rectangular cutout portion 51 extending forward from the rear-end opening of the rear axle 4, a pair of side walls 52 formed on both circumferential sides of the cutout portion 51, a first support portion 53 provided at the front end of the cutout portion 51, and a first front wall 54 provided in front of the first support portion 53. The pair of side walls 52, the first support portion 53, and the first front wall 54 are protrusions that protrude in the same direction from the outer surface of the rear axle 4, and each has a flat tip surface. As shown in FIG. 6 , the heights of the protrusions decrease in the order of the pair of side walls 52, the first front wall 54, and the first support portion 53. The pair of side walls 52 have cylindrical outer surfaces relative to each other. The front surface of the first front wall 54 has a cylindrical surface. As a result, the pair of side walls 52 and the first front wall 54 are formed so as to be inscribed within a cylinder having a central axis perpendicular to the central axis of the rear body 4.

[0020] FIG. 7 is a perspective view of the inner tube 5 of the knock-type writing instrument 1 of FIG. 1 , FIG. 8 is a side view of the inner tube 5 of FIG. 7 , and FIG. 9 is a longitudinal cross-sectional view of the inner tube 5 of FIG. The inner tube 5 is a cylindrical member. Two rectangular recesses 5a are formed on the outer surface of the front of the inner tube 5. The recesses 5a are recesses of a uniform depth from the outer surface of the inner tube 5. The two recesses 5a are positioned opposite each other across the central axis of the inner tube 5. The rectangular recess 5a has a substantially U-shaped U-hole 5b formed therein, consisting of a through-hole along the rear edge and two through-holes extending forward from each end of the through-hole. The U-hole 5b defines an elastically deforming portion 5c within the recess 5a. The elastically deforming portion 5c defined by the U-hole 5b is a cantilever beam extending rearward. A protrusion 5d protruding radially outward is formed on the outer surface of each of the elastically deforming portions 5c. The convex portions 5d are spherical protrusions. The circumscribing circle of the two convex portions 5d is formed so as to be slightly larger in diameter than the inscribing circle of the two reduced diameter portions 4b of the rear body 4 with respect to the central axis.

[0021] A second retaining portion 50b is provided on the side surface of the inner tube 5 near the rear end. The second retaining portion 50b and each of the two elastically deforming portions 5c are positioned 90 degrees apart in the rotational direction around the central axis. The second retaining portion 50b includes a base portion 55 that protrudes radially outward from the side surface of the inner tube 5 and a disk-shaped cover portion 56 provided at the tip of the base portion 55. The central axis of the cover portion 56 is perpendicular to the central axis of the inner tube 5. A second front wall 57 extending radially inward is provided at the front end of the cover portion 56. Furthermore, a second support portion 58 extending radially inward beyond the second front wall 57 is provided at the rear of the second front wall 57. A first recess 59a is provided between the base portion 55 and the second support portion 58. The first recess 59a is open radially inward and penetrates laterally. A second recess 59b is provided near the base 55 on the opposite side of the base 55 from the first recess 59a. The second recess 59b is open toward the rear and penetrates in the same direction as the first recess 59a. The first recess 59a and the second recess 59b are disposed at equal distances from the central axis of the inner cylinder 5.

[0022] Four outer cams 20, which are cam protrusions, are provided on the inner surface of the rear end of the inner cylinder 5 at equal intervals along the circumferential direction. Adjacent outer cams 20 define four first guide grooves 21 extending in the front-rear direction. Each outer cam 20 is composed of a first protrusion 22 and a second protrusion 23 extending in the front-rear direction and arranged continuously in the circumferential direction. The first protrusions 22 and the second protrusions 23 have the same shape. The front end surfaces of the first protrusions 22 and the second protrusions 23 are slopes inclined at the same angle relative to the circumferential direction. A second guide groove 24 extending in the front-rear direction is formed between the first protrusions 22 and the second protrusions 23. The circumferential width of the first guide groove 21 is greater than the circumferential width of the second guide groove 24. The depths of the first guide groove 21 and the second guide groove 24 are the same. In the outer cam 20, restricting surfaces 25 are provided at the rear ends of the first guide groove 21 and the second guide groove 24.

[0023] FIG. 10 is a longitudinal cross-sectional view of the knock member 30 of the knock-type writing instrument 1 of FIG. 1 , and FIG. 11 is a longitudinal cross-sectional view of the knock member 30 of FIG. 10 . The knock member 30 is a cylindrical member formed with a gentle tapered shape toward the rear. Eight locking protrusions 31 are provided at equal intervals along the circumferential direction on the front outer surface of the knock member 30. Each of the locking protrusions 31 is configured to be positioned within the first guide groove 21 between adjacent outer cams 20 or within the second guide groove 24 between the first protrusion 22 and the second protrusion 23. Each of the locking protrusions 31 is configured to move back and forth within the first guide groove 21 or the second guide groove 24 in response to a knock operation. A cam surface 32 is formed on the front end surface of the knock member 30. The cam surface 32 has eight peaks 33 and valleys 34. Slopes are formed between the peaks 33 and the valleys 34. A circular crown 35 is attached to the rear end of the knock member 30.

[0024] Eight first restricting portions 36, each having a slender protrusion shape, are provided at equal intervals along the circumferential direction on the inner surface of the knock member 30, extending rearward from near the front end. Each first restricting portion 36 has a shape resembling a truncated side of a cylinder having a central axis parallel to the central axis of the knock member 30. Therefore, a cross section of each first restricting portion 36, i.e., a cross section perpendicular to the central axis, has an arc-shaped contour. Furthermore, since the side surfaces of the knock member 30 are formed with a substantially uniform thickness, the inner surface of the knock member 30 is gently tapered rearward in accordance with the outer shape of the knock member 30. Therefore, the protruding first restricting portions 36 are formed so that their height gradually decreases rearward. A spherically curved surface portion 36a is formed at the front end of each first restricting portion 36. An annular protrusion 37 is provided on the inner surface of the knock member 30, extending around the central axis to connect each of the first restricting portions 36.

[0025] FIG. 12 is a perspective view of the rotor 40 of the knock-type writing instrument 1 of FIG. 1. The rotor 40 is a cylindrical member. The rotor 40 consists of an insertion portion 41, which is inserted into the interior of the knock member 30 from the front end and used for centering, and a larger-diameter portion 42, which is located in front of the insertion portion 41 and has a larger diameter. The insertion portion 41 is gently tapered toward the rear. A cam receiving surface 43 is formed on the annular rear end surface of the large-diameter portion 42, and cooperates with and has a complementary shape to the cam surface 32 of the knock member 30. The cam receiving surface 43 has eight peaks 44 and valleys 45, similar to the cam surface 32 of the knock member 30. Slopes are formed between the peaks 44 and valleys 45. Four inner cams 46, which are protrusions extending in the front-to-rear direction, are provided at equal intervals along the circumferential direction on the outer surface of the large-diameter portion 42. The width of the inner cam 46 in the circumferential direction is smaller than the width of the first guide groove 21 and larger than the width of the second guide groove 24 .

[0026] The outer surface of the insertion portion 41 is provided with two elongated, protruding second restriction portions 47 extending forward from the rear end. The two second restriction portions 47 are positioned opposite each other across the central axis of the rotor 40. The cross section of each second restriction portion 47, i.e., a cross section perpendicular to the central axis of the rotor 40, is a substantially isosceles trapezoid. A planar apex 47a is formed along the longitudinal direction of the second restriction portion 47 by the portion corresponding to the upper base of the trapezoid. The apex 47a extends substantially parallel to the central axis of the rotor 40. The insertion portion 41 is also formed with a gentle taper toward the rear. Therefore, the protruding second restriction portions 47 are formed so that their height gradually increases toward the rear. The rear end of the second restriction portion 47 is formed with a chamfered portion 47b that resembles an oblique cutoff.

[0027] The assembly of the knock-type writing instrument 1 will be described primarily with reference to FIG. 3 . First, the spring 7 is inserted through the rear end opening of the front barrel 3, followed by the refill 6. Meanwhile, the knock member 30 is inserted through the front end opening of the inner barrel 5, followed by the rotor 40. The second end 62 of the clip member 60 is pressed from the rear side against the second recess 59b of the second retaining portion 50b of the inner barrel 5 to engage with it. That is, the gap of the second recess 59b, which opens toward the rear, is formed slightly narrower than the outer diameter of the metal wire of the clip member 60. Therefore, by pressing the second end 62 against the second recess 59b, the second end 62 snaps into the second recess 59b. Next, the first end 61 of the clip member 60 is placed in the first recess 59a of the second retaining portion 50b of the inner barrel 5. The gap of the first recess 59a, which opens radially inward, is formed larger than the outer diameter of the metal wire of the clip member 60. Therefore, the first end 61 can be easily positioned in the first recess 59a by elastically deforming the clip member 60. As a result, the clip member 60 is attached to the second holding portion 50b so as to surround the base portion 55.

[0028] The inner cylinder 5, into which the knock member 30 and rotor 40 are inserted and the clip member 60 is attached, is inserted through the rear end opening of the rear axle 4 and press-fitted, thereby attaching the inner cylinder 5 to the rear axle 4. At this time, the inner cylinder 5 is aligned in the rotational direction so that the base portion 55 of the second retaining portion 50b of the inner cylinder 5 is received within the cutout portion 51 of the rear axle 4. The outer diameter of the front end of the inner cylinder 5 is slightly larger than the diameter of the inscribed circle of the reduced diameter portion 4b of the rear axle 4. However, because an inclined surface 4c is formed at the rear end of the reduced diameter portion 4b of the rear axle 4, the front edge of the inner cylinder 5 passes over the reduced diameter portion 4b, allowing the inner cylinder 5 to be inserted all the way.

[0029] When the inner tube 5 is attached to the rear axle 4, the reduced diameter portion 4b of the rear axle 4 is housed in the recess 5a of the inner tube 5. Even if a force acts on the inner tube 5 such that it is pulled out of the rear axle 4, the front end edge 4d of the reduced diameter portion 4b of the rear axle 4 engages with the step 5e in front of the recess 5a of the inner tube 5, preventing the inner tube 5 from unintentionally coming off the rear axle 4. Furthermore, the protrusion 5d of the elastically deforming portion 5c abuts against the reduced diameter portion 4b of the rear axle 4, causing the elastically deforming portion 5c to elastically deform so as to curve radially inward. In this state, if the front end opening of the rear axle 4 is pointed vertically downward, gravity will move the knock member 30 and the rotor 40 downward, but the front end edge or front end face of the rotor 40 will engage with the rear end edge 5f or rear end face of the elastically deforming portion 5c. Therefore, even if the front end opening of the rear barrel 4 is oriented vertically downward after being removed from the front barrel 3 when replacing the refill, the rotor 40 will not fall off the rear barrel 4 and the inner cylinder 5.

[0030] When the base portion 55 of the second retaining portion 50b is inserted deep into the cutout portion 51 of the rear axle 4, the first retaining portion 50a and the second retaining portion 50b fit together to form the clip retaining portion 50. That is, the base portion 55 of the second retaining portion 50b and the clip member 60 attached to the base portion 55 are disposed between the pair of side walls 52 of the first retaining portion 50a. Furthermore, as shown in FIG. 2 , the first support portion 53 and the first front wall 54 of the first retaining portion 50a complementarily abut the second support portion 58 and the second front wall 57 of the second retaining portion 50b, respectively, thereby surrounding the first end portion 61 of the clip member 60. In other words, the first end portion 61, which is the mounting portion of the clip member 60, is radially sandwiched between the first retaining portion 50a and the second retaining portion 50b. As a result, the clip member 60 is attached to the barrel 2 by the clip retaining portion 50.

[0031] The clip holder 50 is generally cylindrical in shape, formed by a pair of side walls 52 and a first front wall 54 of the first holder 50a and a cover 56 and a second front wall 57 of the second holder 50b. The clip member 60 is disposed so as to penetrate the generally cylindrical clip holder 50 laterally along the central axis of the knock-type writing instrument 1. Therefore, the attachment portion of the clip member 60, i.e., the first end 61 and the second end 62, are generally concealed by the clip holder 50. Therefore, the attachment structure, i.e., the portion of the clip member 60 involved in attachment, cannot be seen from the outside, improving the design of the attachment structure of the clip member 60. Furthermore, in the knock-type writing instrument 1, the clip member 60 can be easily disassembled by removing the inner barrel 5 from the rear barrel 4.

[0032] Figure 13 is a partial perspective view illustrating the fitting of the front barrel 3 and rear barrel 4 of the knock-type writing instrument 1 of Figure 1. After the inner tube 5 is attached to the rear barrel 4, the rear barrel 4 is screwed onto the front barrel 3 into which the refill 6 and spring 7 have been inserted. As described above, a first locking portion 8 is provided on the outer surface of the rear end of the front barrel 3, while a second locking portion 9 is provided on the inner surface of the rear barrel 4, as shown in Figure 13. The second locking portion 9 is a protrusion provided near the end point of the female thread portion 4a, and is formed at approximately the same height as the threads of the female thread portion 4a and so as to close the valley of the female thread portion 4a.

[0033] The first locking portion 8 of the front barrel 3 and the second locking portion 9 of the rear barrel 4 are arranged so as to climb over each other when the front barrel 3 and the rear barrel 4 are completely screwed together. Even if a rotational force acts in a direction that would unscrew the front barrel 3 and the rear barrel 4 due to vibrations or the like when writing with the knock-type writing instrument 1, the first locking portion 8 and the second locking portion 9 will lock together, preventing unintended unscrewment. The first locking portion 8 and the second locking portion 9 may be protrusions of any shape and arranged in any position, as long as they climb over each other and lock together when the front barrel 3 and the rear barrel 4 are screwed together.

[0034] Furthermore, as a result of being in a threaded state for a long period of time, the threads of the male threaded portion 3 a and the female threaded portion 4 a may deform due to creep, causing the amount of tightening to become greater than expected. If the front axle 3 is further tightened onto the rear axle 4 in this case, there is a risk that the start point 3 b of the male threaded portion 3 a of the front axle 3 will come into contact with the second locking portion 9 of the rear axle 4. To prevent this contact between the male threaded portion 3 a of the front axle 3 and the second locking portion 9 of the rear axle 4, when the front axle 3 and the rear axle 4 are completely threaded together before creep occurs, the start point 3 b of the male threaded portion 3 a of the front axle 3 is spaced a predetermined angle from the second locking portion 9 of the rear axle 4. In other words, the start point 3 b of the male threaded portion 3 a of the front axle 3 is spaced a predetermined angle from the first locking portion 8. The predetermined angle between the start point 3 b of the male threaded portion 3 a of the front axle 3 and the first locking portion 8 is, for example, 90 degrees.

[0035] FIG. 14 is a schematic diagram illustrating the switching of the knock-type writing instrument 1 of FIG. 1 from a non-writing state to a writing state. That is, FIG. 14 is a schematic diagram illustrating the positional relationship between the outer cam 20, the knock member 30, and the rotor 40. The outer cam 20 is circumferentially expanded, and the positions of the locking protrusion 31 of the knock member 30 and the inner cam 46 of the rotor 40 are shown. In the figure, the lower side is the front of the knock-type writing instrument 1, and the upper side is the rear of the knock-type writing instrument 1. For convenience, the shapes of the restricting surfaces 25 provided at the rear ends of the first guide groove 21 and the second guide groove 24 and the locking protrusion 31 of the knock member 30 are simplified. The rotor 40 is provided with a rotational force by the cooperation of the cam surface 32 of the knock member 30 and the cam receiving surface 43 of the rotor 40, causing it to rotate around its central axis. Therefore, the rotor 40 moves from right to left in FIG. 14 with each knock operation.

[0036] 14(a) is a schematic diagram showing the non-writing state of the knock-type writing instrument 1. At this time, the inner cam 46 of the rotor 40, which is biased rearward by the spring 7 via the refill 6, is positioned in the first guide groove 21 between the outer cams 20. Therefore, in this state, the writing part 6a is sunk into the barrel 2. The locking protrusion 31 of the knock member 30 is positioned in the first guide groove 21 or the second guide groove 24. The cam surface 32 and the cam receiving surface 43 are positioned out of phase with each other.

[0037] 14(a), a knocking operation is performed to press the knock member 30 forward against the biasing force of the spring 7, thereby moving the knock member 30 and the rotor 40 forward. At this time, the locking protrusion 31 of the knock member 30 and the inner cam 46 of the rotor 40 move forward within the first guide groove 21. Furthermore, the knock member 30 and the rotor 40 are subjected to circumferential force components in opposite directions via the slopes of the cam surface 32 and the cam receiving surface 43, but the rotation of the rotor 40 is restricted by the contact between the locking protrusion 31, which is disposed within the second guide groove 24, and the side surfaces of the first protrusion 22 and the second protrusion 23 of the outer cam 20.

[0038] As the knock member 30 and rotor 40 move further forward, the rear end of the inner cam 46 passes over the front end of the outer cam 20, i.e., the first protrusion 22, in the longitudinal direction (FIG. 14B). At this time, the restriction on the rotation of the rotor 40 by the outer cam 20 is released, and the cam surface 32 and the cam receiving surface 43 coincide with each other.

[0039] When the pressure on the knock member 30 is released from the state in which the cam surface 32 and the cam receiving surface 43 are aligned, the knock member 30 and the rotor 40 move backward due to the biasing force of the spring 7. At this time, the rotor 40 receives a component force from the inclined surface of the outer cam 20 and rotates around the central axis. That is, the inner cam 46 of the rotor 40 moves along the inclined surface of the outer cam 20 until it abuts against the front end side surface of the second protrusion 23, and the rotation of the rotor 40 stops. Because the width of the inner cam 46 is smaller than the width of the first guide groove 21 and larger than the width of the second guide groove 24, the inner cam 46 cannot enter the second guide groove 24. Therefore, the inner cam 46 engages with the front end surface of the first protrusion 22, restricting the backward movement of the rotor 40 ( FIG. 14( c) ). As a result, the writing part 6a of the refill 6, which is disposed in front of the rotor 40, protrudes from the barrel 2, and the knock-type writing instrument 1 enters a writing state.

[0040] Fig. 15 is a schematic diagram showing the switching from the writing state to the non-writing state of the knock-type writing instrument 1 of Fig. 1. Fig. 15 shows the positional relationship between the outer cam 20, the knock member 30, and the rotor 40 in the same manner as Fig. 14.

[0041] FIG. 15( a) is a schematic diagram showing the writing state of the knock-type writing instrument 1, and is the same as FIG. 14( c). From the state shown in FIG. 15( a), a knock operation is performed to press the knock member 30 forward against the biasing force of the spring 7, thereby moving the knock member 30 and the rotor 40 forward. At this time, the locking protrusion 31 of the knock member 30 and the inner cam 46 of the rotor 40 move forward within the first guide groove 21. Furthermore, the knock member 30 and the rotor 40 are subjected to circumferential force components in opposite directions via the slopes of the cam surface 32 and the cam receiving surface 43. However, the rotation of the rotor 40 is restricted by the contact between the locking protrusion 31, which is disposed within the second guide groove 24, and the side surfaces of the first protrusion 22 and the second protrusion 23 of the outer cam 20.

[0042] As the knock member 30 and rotor 40 move further forward, the rear end of the inner cam 46 passes the front end of the outer cam 20, i.e., the second protrusion 23, in the longitudinal direction (FIG. 15B). At this time, the restriction on the rotation of the rotor 40 by the outer cam 20 is released, and the cam surface 32 and the cam receiving surface 43 coincide with each other.

[0043] When the pressure on the knock member 30 is released from the state in which the cam surface 32 and the cam receiving surface 43 are aligned, the knock member 30 and the rotor 40 retract due to the biasing force of the spring 7. At this time, the rotor 40 receives a component force from the inclined surface of the outer cam 20 and rotates around the central axis. That is, the inner cam 46 of the rotor 40 enters the first guide groove 21 from the inclined surface of the outer cam 20 and moves rearward, causing the knock member 30 and the rotor 40 to retract. The retraction of the knock member 30 and the rotor 40 is restricted by the engagement of the locking protrusion 31 of the knock member 30 with the restricting surfaces 25 provided at the rear ends of the first guide groove 21 and the second guide groove 24 ( FIG. 15( c) ). As a result, the writing portion 6 a of the refill 6 located in front of the rotor 40 retracts into the barrel 2, and the knock-type writing instrument 1 enters a non-writing state.

[0044] Figure 16 is an assembled cross-sectional view of the knock member 30 and rotor 40 of the knock-type writing instrument 1 of Figure 1. Although not shown in Figure 16, as described above, two second restricting portions 47 are provided from the rear end of the insertion portion 41 of the rotor 40 toward the front. The first restricting portion 36 of the knock member 30 and the second restricting portion 47 of the rotor 40 are basically provided so that their positions in the axial direction overlap.

[0045] With each knock operation, the rotor 40 rotates by a predetermined rotation angle, repeatedly engaging and disengaging with the outer cam 20. Four outer cams 20 are provided at equal intervals along the circumferential direction on the inner surface of the inner cylinder 5, so the rotor 40 alternately engages and disengages with the outer cams 20 four times during one rotation. Therefore, the predetermined rotation angle of the rotor 40 with each knock operation is specifically 45 degrees.

[0046] Figure 17 is a cross-sectional view taken along line A-A in Figure 16, corresponding to the knock-type writing instrument 1 during a knocking operation, and Figure 18 is a cross-sectional view taken along line A-A in Figure 16, corresponding to the knock-type writing instrument 1 in a writing state. The state shown in Figure 17 corresponds to the states shown in Figures 14(b) and 15(b). The state shown in Figure 18 corresponds to the states shown in Figures 14(a), 14(c), 15(a), and 15(c).

[0047] 17, in the knock-type writing instrument 1 during the knocking operation, the first restricting portion 36 of the knock member 30 and the second restricting portion 47 of the rotor 40 do not coincide 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 restricting portion 36 of the knock member 30 and the second restricting portion 47 of the rotor 40 coincide in the rotational direction, i.e., are aligned in the radial direction.

[0048] Here, eight first restricting portions 36 are provided on the knock member 30, and two second restricting portions 47 are provided on the rotor 40. The heights of the first restricting portions 36 from the inner surface of the knock member 30 and the heights of the second restricting portions 47 from the outer surface of the rotor 40 are set so that the outer diameter of the inscribed circle for the eight first restricting portions 36 is equal to or slightly smaller than the outer diameter of the circumscribed circle for the two second restricting portions 47.

[0049] The radial alignment of the first and second restricting portions 36 and 47 restricts radial movement of the knock member 30 relative to the rotor 40. Specifically, for example, in the knock-type writing instrument 1 in the writing state, the rotor 40 is biased against the outer cam 20 by the spring 7 via the refill 6, thereby fixing the rotor 40. On the other hand, the biasing force of the spring 7 does not act on the knock member 30, but radial movement of the knock member 30 relative to the fixed rotor 40 is restricted. Therefore, the knock member 30 does not rattle radially relative to the rotor 40. Furthermore, by making the outer diameter of the inscribed circle for the eight first restricting portions 36 slightly smaller than the outer diameter of the circumscribed circle for the two second restricting portions 47, the first restricting portions 36 and the second restricting portions 47 abut against each other. As a result, the knock member 30 and the rotor 40 are locked or fitted together, restricting axial movement of the knock member 30 relative to the rotor 40. Therefore, the knock member 30 does not rattle in the axial direction relative to the rotor 40 .

[0050] Because the first restricting portion 36 of the knock member 30 has a cross-sectional shape with an arcuate outline, the first restricting portion 36 can smoothly slide against the second restricting portion 47 of the rotating rotor 40. As a result, the first restricting portion 36 and the second restricting portion 47 can be smoothly aligned in the radial direction. Furthermore, because the second restricting portion 47 of the rotor 40 has a flat top portion 47a, the first restricting portion 36 and the second restricting portion 47 can be more reliably locked or fitted with the arcuate top portion of the first restricting portion 36 when they are aligned in the radial direction. Furthermore, because the front end of the first restricting portion 36 is provided with a curved surface portion 36a and the rear end of the second restricting portion 47 of the rotor 40 is provided with a chamfered portion 47b, smooth sliding contact can be achieved even if the front end of the first restricting portion 36 and the rear end of the second restricting portion 47 collide with each other when the knock member 30 moves axially relative to the rotor 40.

[0051] As described above, a single knock operation rotates the rotor 40 by 45 degrees, and the eight first restriction portions 36 are also spaced apart by a rotation angle of 45 degrees. Therefore, the first restriction portions 36 and the second restriction portions 47 are aligned in the radial direction not only when the knock-type writing instrument 1 is in the writing state but also when it is in the non-writing state. In other words, during the knock operation, as shown in FIG. 17 , the first restriction portions 36 are positioned between adjacent second restriction portions 47, so the first restriction portions 36 and the second restriction portions 47 are not aligned in the radial direction. Therefore, the knock operation is not impeded. In addition, when the knock-type writing instrument 1 is in the non-writing state, the knock member 30 and the rotor 40 are integrally biased by the spring 7 via the refill 6, so there is no rattle of the knock member 30 relative to the rotor 40.

[0052] While the above-described knock-type writing instrument 1 has eight first restricting portions 36, it may have only four first restricting portions 36 so that the first restricting portions 36 and the second restricting portions 47 are aligned only when the knock-type writing instrument 1 is in the writing state. In short, it is sufficient to provide at least the same number of first restricting portions 36 as the number of times the knock-type writing instrument 1 is in the writing state during one rotation of the rotor 40. The first restricting portions 36 are provided according to the rotation angle of the rotor 40 resulting from one knock operation. Furthermore, the shape and number of the first restricting portions 36 and the second restricting portions 47 may be configured arbitrarily, as long as the knock members 30 and the rotors 40 are restricted or locked the same number of times the knock-type writing instrument 1 is in the writing state during one rotation of the rotor 40.

[0053] For example, while the first and second restricting portions 36 and 47 are both ribs extending in the longitudinal direction, one or both of the first and second restricting portions 36 and 47 may be protrusions positioned to restrict or lock the knock-type writing instrument 1 when the writing instrument is in the writing state. The second restricting portion 47 may be at least two, preferably three or more, protrusions or ribs arranged symmetrically about the central axis of the rotor 40. By providing three or more second restricting portions 47 and restricting or locking the knock member 30 with the corresponding first restricting portions 36 at three or more locations, any radial rattle of the knock member 30 relative to the rotor 40 can be reliably suppressed. Furthermore, one or both of the inner surface of the knock member 30 and the outer surface of the insertion portion 41 of the rotor 40 may be formed to have a substantially polygonal cross section. In this case, the corners of the polygon may serve as the first restricting portion 36 or the second restricting portion 47 to restrict or lock the knock member 30 and the rotor 40.

[0054] The insertion portion 41 of the rotor 40 may be provided with one or more slits extending forward from the rear end opening. This allows the insertion portion 41 as a whole to expand and contract in the radial direction, absorbing manufacturing errors. That is, it is possible to reliably achieve the outer diameter of the inscribed circle for the eight first restricting portions 36 being equal to or slightly smaller than the outer diameter of the circumscribed circle for the two second restricting portions 47, thereby reliably suppressing rattle of the knock member 30 relative to the rotor 40.

[0055] Figure 19 is a perspective view of the second knock type writing instrument 100 in a non-writing state, Figure 20 is a side view of the knock type writing instrument 100 of Figure 19, Figure 21 is a longitudinal cross-sectional view of the knock type writing instrument 100 of Figure 19, and Figure 22 is an exploded perspective view of the knock type writing instrument 100 of Figure 19. As mentioned above, common reference numerals are used to designate corresponding components throughout the drawings. Compared to the first knock type writing instrument 1, the second knock type writing instrument 100 has the same refill 6, spring 7, outer cam 20, knock member 30, and rotor 40, and therefore a description of these components will be omitted.

[0056] The knock-type writing instrument 100 has a barrel 102 equipped with a front barrel 103 and a rear barrel 104 that screws onto the outer surface of the rear end of the front barrel 103, an inner barrel 105 inserted inside the rear end of the barrel 102, a refill 6 that is a writing body disposed inside the barrel 102 and equipped with a writing portion 6a at one end, and a spring 7 that urges the refill 6 rearward. The barrel 102 may be referred to as including the inner barrel 105.

[0057] An outer cam 20, which is a cam projection, is formed on the inner surface of the barrel 102, i.e., the inner surface of the inner barrel 105. A knock member 30 is disposed inside the rear end of the barrel 102, i.e., inside the rear end of the inner barrel 105, with a portion of the knock member 30 protruding rearward from the rear end of the inner barrel 105. A rotor 40 is disposed in front of the knock member 30. The rear end face of the refill 6, which is biased rearward by the spring 7, abuts against the front end face of the rotor 40. Therefore, the rotor 40 is constantly biased rearward by the spring 7 via the refill 6. A clip holder 150 is provided on the side of the barrel 102. The clip holder 150 consists of a first holder 150a provided on the front barrel 103 and a second holder 150b provided on the rear barrel 104. A clip member 160 is attached to the barrel 102 by the clip holder 150.

[0058] Figure 23 is a longitudinal cross-sectional view of the front barrel 103 of the knock-type writing instrument 100 of Figure 19. The front barrel 103 is a cylindrical member. The outer surface of the rear end of the front barrel 103 is provided with a male thread 103a that threadably engages with the rear barrel 104. The outer surface of the front barrel 103, from the front of the male thread 103a to the front-end opening from which the writing part 6a protrudes, is covered by a grip 110 formed by two-color molding during the manufacture of the front barrel 103. In the assembled state of the knock-type writing instrument 100, the entire exposed outer surface of the front barrel 103 is covered by the grip 110, allowing the user to grip any part of the front barrel 103 when writing. The grip 110 is made of the same material as the grip 10 of the first knock-type writing instrument 1 described above.

[0059] The inner surface of the front end of the front axle 103 is provided with an annular support surface 103c facing rearward. Provided behind the support surface 103c are four first ribs 103d and two second ribs 103e, each having a surface facing radially inward and extending in the front-to-rear direction. The two second ribs 103e are positioned opposite each other across the central axis of the front axle 103. The four first ribs 103d are divided into two sets, and are equally spaced between each pair of second ribs 103e. The four first ribs 103d and two second ribs 103e are equally spaced along the circumferential direction. Rectangular through-holes 103f are formed in the side surface of the front axle 103 behind each of the four first ribs 103d. In the two-color molding process, when grip portion 110 is molded after front body 103 is molded, the resin material of grip portion 110 passes through through-hole 103f and enters the interior of front body 103, forming protruding buffer portion 111. In other words, buffer portion 111 is made up of part of grip portion 110. Buffer portion 111 is formed integrally with first rib 103d, and has buffer surface 112 that is inclined toward the front of front body 103.

[0060] Figure 24 is a perspective view of rear barrel 104 of knock-type writing instrument 100 of Figure 19, and Figure 25 is a longitudinal cross-sectional view of rear barrel 104 of Figure 24. Rear barrel 104 is a cylindrical member. The inner surface of the front end of rear barrel 104 is provided with female threads 104a that can be threadably engaged with male threads 103a of front barrel 103. Note that, although not shown, a first locking portion similar to that of the first knock-type writing instrument 1 is provided at the start point of male threads 103a of front barrel 103, i.e., at the end of the spiral path of male threads 103a extended rearward from the rear end. On the other hand, although not shown, a second locking portion similar to that of the first knock-type writing instrument 1 is provided on female threads 104a of rear barrel 104. In the second knock-type writing instrument 100, as in the first knock-type writing instrument 1, the first locking portion and the second locking portion are locked to prevent unintentional unscrewing.

[0061] A first retaining portion 150a is provided on the side surface of the rear end of the rear axle 104. The first retaining portion 150a has a first cutout portion 151a that extends forward from the rear end opening of the rear axle 104 and is formed in a generally rectangular shape, and a cylindrical pillar portion 152 that is provided so as to straddle the first cutout portion 151a and has a central axis that is perpendicular to the central axis of the rear axle 104. A portion of the base of the pillar portion 152 is hollowed out by the first cutout portion 151a, and a first support portion 153 that faces radially inward is provided. The tip of the pillar portion 152 is provided flat and circular. An insertion hole 154 with a rectangular cross section that extends parallel to the central axis of the rear axle 104 is defined on the side surface of the pillar portion 152. The insertion hole 154 is in communication with the first cutout portion 151a.

[0062] Figure 26 is a perspective view of the inner barrel 105 of the knock-type writing instrument 100 of Figure 19, Figure 27 is a side view of the inner barrel 105 of Figure 26, and Figure 28 is a vertical cross-sectional view of the inner barrel 105 of Figure 26. The inner barrel 105 is a cylindrical member. The outer cam 20 described above is provided on the inner surface of the rear end of the inner barrel 105.

[0063] A second holding portion 150b is provided on the side surface of the inner tube 105 near the rear end thereof. The second holding portion 150b has a base portion 155 that protrudes radially outward from the side surface of the inner tube 105. A substantially rectangular second cutout portion 151b is formed so as to extend rearward from the front-end opening of the inner tube 105 to the base portion 155. A rear wall 157 is provided on the rear side of the base portion 155. The surface of the rear wall 157 is formed into a cylindrical surface so as to be integrated with the columnar pillar portion 152 of the rear axle 104 when attached to the rear axle 104, as described below. The front side of the base portion 155 is provided, in order from the front end, with a second support portion 158 facing radially outward and a recess 159 that extends continuously and obliquely radially outward from the rear of the second support portion 158. An end portion 155a is provided at the radial tip of the base portion 155.

[0064] FIG. 29 is a perspective view of the clip member 160 of the knock-type writing instrument 100 of FIG. 19 . In FIG. 29 , the right side is the rear side of the knock-type writing instrument 100. The clip member 160 is formed by stamping and bending a plate-shaped member made of a metal such as stainless steel using a press or the like. Therefore, the clip member 160 is a plate-shaped member as a whole. Specifically, the clip member 160 has a stepped attachment portion 161 formed to branch off from the clip member 160. The attachment portion 161 is formed simultaneously with the formation of the first opening 162 further forward and the second opening 163 further rearward. This defines the clip member 160 made of a single, integral plate material having approximately the same width as a whole. The front end of the clip member 160 is curved radially outward, forming a protrusion 164 that grips an article between the clip member 160 and the rear barrel 104. The mounting portion 161 has a curved portion 165 that curves in an arc shape from the rear end of the first opening 162, a clamping portion 166 that bends approximately 90 degrees from the curved portion 165 and extends forward, and a tip portion 167 that bends approximately 90 degrees from the clamping portion 166 and extends radially inward.

[0065] 30 is a longitudinal cross-sectional view illustrating the attachment of the clip member 160 to the knock-type writing instrument 100 of FIG. 19. First, as shown in FIG. 30(a), the clip member 160 is placed on the base portion 155 of the second holding portion 150b of the inner tube 105. Specifically, the clamping portion 166 of the clip member 160 is placed on the second support portion 158, and the tip portion 167 of the clip member 160 is placed on the rear end of the second cutout portion 151b, in other words, the front end of the base portion 155. Alternatively, the rear portion of the curved portion 165 of the clip member 160 is placed on the end portion 155a of the base portion 155, and the front portion of the curved portion 165 of the clip member 160 is placed on the recess 159.

[0066] Next, as shown in FIG. 30( b), the inner tube 105 is aligned in the rotational direction so that the base portion 155 of the second retaining portion 150b of the inner tube 105 is received in the first cutout portion 151a of the rear axle 104, and the front end of the inner tube 105 is inserted into the interior of the rear end portion of the rear axle 104. At this time, the front end of the clip member 160 is inserted into the insertion hole 154 of the first retaining portion 150a of the rear axle 104. Specifically, the rear end of the clip member 160 is moved radially inward, and the front end of the clip member 160 is moved radially outward using the end 155a of the base portion 155 as a fulcrum. This allows the front end of the clip member 160 to be inserted into the insertion hole 154.

[0067] Next, as shown in FIG. 30( c), the inner cylinder 105 together with the clip member 160 is further inserted and press-fit into the rear axle 104. As a result, the first retaining portion 150a and the second retaining portion 150b are fitted together to form the clip retaining portion 150. That is, the base portion 155 of the second retaining portion 150b and the clip member 160 attached to the base portion 155 are disposed within the pillar portion 152 of the first retaining portion 150a. Furthermore, the clamping portion 166 of the clip member 160 is clamped radially between the first support portion 153 of the first retaining portion 150a and the second support portion 158 of the second retaining portion 150b. In other words, the mounting portion 161 of the clip member 160 is clamped radially between the rear axle 104 and the inner cylinder 105. As a result, the clip member 160 is attached to the barrel 102 by the clip holding portion 150 which is integrally formed by the first holding portion 150a and the second holding portion 150b.

[0068] The clip holder 150 is formed into a generally cylindrical shape by the pillar portion 152 of the first holder 150a and the rear wall 157 of the second holder 150b. The clip member 160 is disposed so as to penetrate the generally cylindrical clip holder 150 laterally along the central axis of the knock-type writing instrument 100. Therefore, the attachment portion of the clip member 160, i.e., the clamping portion 166, is substantially concealed by the generally cylindrical clip holder 150. Therefore, as shown in FIGS. 19 and 20 , the attachment structure, i.e., the portion of the clip member 160 involved in attachment, cannot be seen from the outside, improving the design of the attachment structure of the clip member 160. Furthermore, the minimal amount of unnecessary gaps in the attachment structure prevents dust and other foreign matter from entering the attachment structure. Furthermore, in the knock-type writing instrument 100, the clip member 160 has no connecting parts such as press-fitting or fitting with the rear barrel 104 or the inner barrel 105, and therefore the clip member 160 can be more easily disassembled by removing the inner barrel 105 from the rear barrel 104. As a result, the rear barrel 104, the inner barrel 105, or the clip member 160 can be easily recycled or reused.

[0069] In the clip member 160, the front end of the clip member 160 is biased radially inward due to the shape of the attachment portion 161, particularly the shape of the curved portion 165. As a result, an article can be gripped between the protrusion 164 of the clip member 160 and the outer surface of the barrel 102, specifically the outer surface of the rear barrel 104. To release the grip, the rear end of the clip member 160 is pressed radially inward, elastically deforming the attachment portion 161 with the end 155a of the base portion 155 as a fulcrum. This causes the front end of the clip member 160 to move radially outward, thereby releasing the grip. The clip holding portion 150 has a sufficiently large insertion hole 154, so that the swinging of the clip member 160 is not hindered.

[0070] Figure 31 is a vertical cross-sectional view of the front end of the knock-type writing instrument 100 of Figure 19. The refill 6 includes the writing part 6a described above, an ink reservoir 6b that contains ink to be supplied to the writing part 6a, and a joint 6c that connects the writing part 6a and the ink reservoir 6b. The writing part 6a is a ballpoint pen tip that holds a ball at its tip. The front end of the spring 7 is supported by the support surface 103c of the front shaft 103, and the rear end of the spring 7 is supported by the front end surface of a flange 6d that is provided on the joint 6c and protrudes radially outward. As a result, the refill 6 is biased rearward by the spring 7. The spring 7 is surrounded by a first rib 103d and a second rib 103e, which restricts radial deflection.

[0071] For example, if the knock-type writing instrument 100 is accidentally dropped onto the floor from the rear end, i.e., from the knock member 30 side, the impact and recoil of the drop cause the refill 6 to rapidly move relatively forward within the barrel 102. The movement of the refill 6 is restricted when the flange portion 6d of the joint 6c collides with the buffer surface 112 of the buffer portion 111. The buffer portion 111 is formed of a softer viscoelastic material than the front barrel 103, and therefore can cushion the impact of the refill 6 upon collision. If the buffer portion 111 were not present, the refill 6 would collide with the inner surface of the front barrel 103, which is made of hard plastic. As a result, the impact would not be sufficiently cushioned, and there is a risk that the ball held at the tip of the writing portion 6a would fly out due to inertial force. The impact of the refill 6 is cushioned by the collision with the buffer surface 112, preventing the ball from flying out and reducing other damage to the refill 6.

[0072] The buffer portion 111 may have any shape and arrangement as long as it penetrates from the outside to the inside of the barrel 102 and can absorb the impact of the refill 6. For example, in the knock-type writing instrument 100, the flange portion 6d of the joint 6c collides with the buffer portion 111. However, a through-hole may be provided near the front end opening of the front barrel 103, and a corresponding buffer portion may be provided in a two-color molding process. In this case, the writing portion 6a, rather than the joint 6c of the refill 6, collides with the buffer portion, thereby absorbing the impact. Furthermore, the buffer portion may be provided by penetrating a separate member from the outside to the inside of the barrel 102, rather than by a two-color molding process. The configuration of the buffer portion 111 that absorbs the impact of the refill 6 in the second knock-type writing instrument 100 may be applied to the first knock-type writing instrument 1.

[0073] Refill 6 may be a writing implement other than a ballpoint pen, such as a marking pen, a touch pen, or an eraser. In addition, a part or all of knock member 30 including crown 35 may be an erasing portion that erases handwriting made with a knock-type writing implement.

[0074] The refill 6 may be a ballpoint pen containing thermochromic ink. Thermochromic ink refers to ink that maintains a predetermined color (first color) at room temperature (e.g., 25°C), changes to a different color (second color) when heated to a predetermined temperature (e.g., 60°C), and then returns to its original color (first color) when cooled to a predetermined temperature (e.g., -5°C). In a thermochromic writing instrument using thermochromic ink, the second color is colorless, and "erasing" refers to heating a line drawn in the first color (e.g., red) to make it colorless. Therefore, a friction member, which serves as the erasing part, rubs against the writing surface on which the line was drawn, generating frictional heat, thereby changing the drawn line to colorless, i.e., erasing it. Naturally, the second color may be a color other than colorless.

[0075] The above description has used a knock-type writing instrument as an example of a writing instrument, but the configurations or structures that are common between knock-type writing instruments and other writing instruments, such as cap-type writing instruments and multi-core writing instruments, such as the structure of the first locking portion of the male thread portion and the second locking portion of the female thread portion, or the attachment structure of the clip member, can be similarly applied to other writing instruments.

[0076] For example, the structure of the first locking portion of the male threaded portion and the second locking portion of the female threaded portion includes a male threaded member having a male threaded portion and a tubular female threaded member having a female threaded portion and capable of being threadedly engaged with the male threaded member, the male threaded member having the first locking portion and the female threaded member having the second locking portion, and the first locking portion and the second locking portion overcome each other when the male threaded member and the female threaded member are threaded together, so long as the first locking portion and the second locking portion are configured to lock together when the male threaded member and the female threaded member are unthreaded. For example, in addition to the front shaft 3 and rear shaft 4 described above, the male threaded member and the female threaded member may be a tip member and a front shaft that threads onto the rear end of the tip member, or a cap and a crown that threads onto the rear end of the cap.

[0077] The clip member mounting structure includes a cylindrical first member having a first retaining portion, a second member having a second retaining portion and inserted into the rear end of the first member to be detachably fitted with the first member, and a clip member having an attachment portion, and the first member and second member may be selected arbitrarily as long as the attachment portion of the clip member is clamped radially between the first and second retaining portions and the clip member is attached to the first member. For example, the first member and second member may be a cap and a crown that fits over the rear end of the cap, in addition to the rear body 104 and inner cylinder 105 described above.

[0078] In the above-described knock-type writing instrument 100, the first holding portion 150a and the second holding portion 150b are fitted together to form the cylindrical clip holding portion 150 as a whole. However, in consideration of design, the first holding portion and the second holding portion may be configured to form a polygonal prism, such as a hexagonal prism, other than a cylindrical shape. Furthermore, the mounting portion may be configured in any shape other than the stepped shape described above, as long as it can be clamped radially between the first holding portion and the second holding portion. For example, the mounting portion may be simply arc-shaped.

[0079] DESCRIPTION OF SYMBOLS 1 Knock-type writing implement 2 Barrel 3 Front barrel 4 Rear barrel 5 Inner barrel 20 Outer cam 30 Knock member 31 Locking protrusion 36 First restricting portion 40 Rotor 41 Insertion portion 47 Second restricting portion 100 Knock-type writing implement 102 Barrel 103 Front barrel 104 Rear barrel 105 Inner barrel 150 Clip retaining portion 150a First retaining portion 150b Second retaining portion 160 Clip member 161 Mounting portion

Claims

1. A knock-type writing instrument comprising a barrel, a knock member formed cylindrically and having a cam surface, and a rotor disposed in front of the knock member, the rotor having a cam receiving surface that cooperates with the cam surface of the knock member and an insertion portion that can be inserted into the knock member, wherein a first regulating portion is formed on the inner surface of the knock member and a second regulating portion is formed on the outer surface of the insertion portion of the rotor, wherein when a knock operation causes the cam surface and the cam receiving surface to cooperate to rotate the rotor relative to the knock member and the knock-type writing instrument is in a writing state, the first regulating portion and the second regulating portion are configured to be aligned radially to regulate the radial movement of the knock member relative to the rotor, and wherein during a knock operation, the first regulating portion and the second regulating portion are configured not to be aligned radially.

2. A knock-type writing instrument as described in claim 1, wherein the first regulating portion and the second regulating portion abut when they are aligned radially, and the knock member and the rotor are engaged in the axial direction.

3. A knock-type writing instrument as described in claim 1 or 2, wherein the first regulating portion and the second regulating portion are protrusions or ribs extending in the longitudinal direction, and the first regulating portion is provided according to the rotation angle of the rotor by a single knock operation.

4. A knock-type writing instrument as described in claim 1 or 2, further comprising a refill with a ballpoint pen tip holding a ball at its tip, a buffer section made of a viscoelastic material that penetrates from the outside to the inside of the barrel, configured so that the forward movement of the refill is regulated by contact with the buffer section, and a grip section is provided on the outer surface of the barrel, and the buffer section consists of a part of the grip section.

5. A knock-type writing instrument as described in claim 1 or 2, comprising a male threaded member having a male threaded portion, and a tubular female threaded member having a female threaded portion and capable of being screwed into the male threaded member, wherein the male threaded portion has a first locking portion and the female threaded portion has a second locking portion, and when the male threaded member and the female threaded member are screwed together, the first locking portion and the second locking portion climb over each other, so that when the male threaded member and the female threaded member are unscrewed from each other, the first locking portion and the second locking portion lock together.

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