Abstract:
Provided are: a ballpoint pen with which the amount of bending of the pen tip can be changed, wobbling does not occur, and a stable writing feel can be obtained; and a ballpoint pen with which, to make it possible to clearly change the thickness of the drawn line by the force applied when writing, lines of different thickness can be written with a single writing tip using the angle of the ballpoint pen tip. The ballpoint pen is provided with: a writing ball; a holder for holding the writing ball by means of a swaged section the tip of which has been swaged; an ink supply section for supplying ink to the holder; a shaft body inside which the ink supply section is held; and a tip shaft, which is connected to the tip of the shaft body and from which the holder protrudes during writing.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a ballpoint pen capable of varying drawn line width. 
       BACKGROUND ART 
       [0002]    As technology related to ballpoint pens that enable tilting of the ballpoint pen tip of a ballpoint pen, ballpoint pens such as those described in Patent Document 1 are known in which an elastic body is interposed between a shaft body and a tip member, such that the ballpoint pen tip is tilted by flexing of the elastic body according to the force during writing. 
       RELATED DOCUMENTS 
     Related Patent Documents 
       [0003]    Patent Document 1: JP 2002-331789 A 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    However, issues with the invention described in Patent Document 1 are that the amount of flexing of the ballpoint pen tip is limited by the gap between the shaft body and the tip member, and that wobbling and change in the writing sensation arise with degeneration of the elastic body, such as rubber or elastomer. 
         [0005]    The present invention accordingly has a first objective of providing a ballpoint pen in which the amount of flexing in the pen tip can be changed according to the force applied during writing, enabling a stable writing sensation to be obtained without wobbling arising. 
         [0006]    A second objective is to provide a ballpoint pen with which, in order to make it possible for the thickness of drawn lines to be markedly varied according to the force applied during writing, it is possible to draw lines of different thicknesses using a single writing tip according to the angle of the ballpoint pen tip. 
       Solution to Problem 
       [0007]    In consideration of the above circumstances, the invention has the following features. Note that reference numerals herein are the reference numerals employed in exemplary embodiments of the present invention, and are not limitations to the technical scope of the present invention. 
         [0008]    (First Aspect and Second Aspect) 
         [0009]    A first aspect of the present invention is a ballpoint pen including a writing ball  30 , a holder  21  that retains the writing ball  30  with a swaged section  23  swaged at a tip end of the holder  21 , an ink supply section  40  that supplies ink into the holder  21 , a shaft body  11  that internally houses the ink supply section  40 , and a tip shaft  12  that is continuously provided at a tip end of the shaft body  11  with the holder  21  projecting out from the tip shaft  12  during writing and the tip shaft  12  exhibiting an elastic action. A second aspect of the present invention is the first aspect, wherein the tip shaft  12  is formed by double molding of a front half  15  and a rear half  16  that are interdigitated with each other in a serrated pattern. 
         [0010]    The shaft body  11  may be capable of directly containing ink internally, or may be a structure that internally houses a refill filled with ink. The ink supply section  40  may supply ink contained in the shaft body  11  to the holder  21  using an intermediate member, such as a collector  41 , or may supply ink contained in an ink containing tube such as a refill that is a separate body to the shaft body  11  to the holder  21 . 
         [0011]    The tip end side of the holder  21  is exposed from the tip shaft  12  during writing, and the rear end side of the holder  21  is positioned inside the tip shaft  12  and in communication with the ink supply section  40 . A non-illustrated ball housing is formed inside the tip of the holder  21 , and the writing ball  30  is gripped by the ball housing. The holder  21  may be formed by machining or injection molding a metal material such as stainless steel, or a resin material such as polyacetal. 
         [0012]    According to the present aspects, a writing sensation akin to that of a fountain pen can be obtained due to the double molded portion interdigitated in a serrated pattern flexing according to the force applied during writing. Moreover, the configuration of the ballpoint pen tip  20  and the outer member  60  enables lines of different thicknesses to be drawn using a single writing tip according to the angle of the ballpoint pen tip. Thus because it is possible to finely adjust the angle of the ballpoint pen tip with respect to the writing surface according to the force applied during writing, the thickness of line drawn is variable markedly, enabling an improvement in the expressiveness of writing to be achieved. 
         [0013]    Note that the double molding referred to here indicates integrally forming two or more types of component, and encompasses molding using the same materials as each other, and forming a multiplex molding in which components are not adhered to each other. 
         [0014]    (Third Aspect) 
         [0015]    The third aspect of the present invention is the second aspect in which a joint  50  is double molded. Namely, the tip shaft  12  comprises the joint  50  fixed to the shaft body  11 , and an outer member  60  that is fixed to the joint  50  and that covers an outer periphery of the holder  21 . The joint  50  is formed by double molding of a front half  15  and a rear half  16  that are interdigitated with each other in a serrated pattern. 
         [0016]    According to the present aspect, similarly to the second aspect, because it is possible to finely adjust the angle of the writing tip with respect to the writing surface according to the force applied during writing, the thickness of line drawn is variable markedly, enabling an improvement in the expressiveness of writing to be achieved. 
         [0017]    (Fourth Aspect) 
         [0018]    A fourth aspect of the present invention is the third aspect, wherein the joint  50  is integrally formed with the outer member  60 . 
         [0019]    According to the present aspect, similarly to the second aspect, because it is possible to finely adjust the angle of the writing tip with respect to the writing surface according to the force applied during writing, the thickness of line drawn is variable markedly, enabling an improvement in the expressiveness of writing to be achieved. 
         [0020]    (Fifth Aspect) 
         [0021]    A fifth aspect of the present invention is the third aspect, wherein the joint  50  is integrally formed with the shaft body  11 . 
         [0022]    According to the present aspect, similarly to the second aspect, because it is possible to finely adjust the angle of the writing tip with respect to the writing surface according to the force applied during writing, the thickness of line drawn is variable markedly, enabling an improvement in the expressiveness of writing to be achieved. 
         [0023]    (Sixth Aspect) 
         [0024]    A sixth aspect of the present invention includes, in addition to the above features, an internal joint  14  interposed between the ink supply section  40  and the holder  21 . 
         [0025]    The holder  21  may be directly connected to the ink supply section  40 , but interposing the internal joint  14  is particularly advantageous in cases in which there is a large difference in diameter between the holder  21  and the ink supply section  40 . 
       Advantageous Effects of Invention 
       [0026]    Being configured as described above, the invention of the present application enables a double molded portion interdigitated in a serrated pattern to be flexed according to the force applied during writing, and enabling a writing sensation akin to that of a fountain pen to be obtained. 
         [0027]    Moreover, it is possible to draw lines of different thicknesses using a single writing tip according to the angle of the ballpoint pen tip. Thus the thickness of line drawn can be varied by finely adjusting the angle of the ballpoint pen tip with respect to the writing surface according to the force applied during writing, enabling easier and higher quality writing of a “stop”, an “upward tick”, and a “sweeping stroke”, and enabling an improvement in the expressiveness of writing to be achieved. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0028]      FIG. 1A  is a front view of a ballpoint pen of a first exemplary embodiment of the present invention, and  FIG. 1B  is a vertical cross-section thereof. 
           [0029]      FIG. 2  is a vertical cross-section of a tip portion of a ballpoint pen of the first exemplary embodiment. 
           [0030]      FIG. 3A  is a perspective view of a joint employed in a ballpoint pen of the first exemplary embodiment, and  FIG. 3B  is a vertical cross-section thereof. 
           [0031]      FIG. 4  is perspective view of a tip shaft of a ballpoint pen of the first exemplary embodiment. 
           [0032]      FIG. 5A  is a front view of a ballpoint pen of a second exemplary embodiment of the present invention, and  FIG. 5B  is a vertical cross-section thereof. 
           [0033]      FIG. 6  is a vertical cross-section of a tip portion of a ballpoint pen of the second exemplary embodiment. 
           [0034]      FIG. 7A  is a perspective view of a joint and a rear half of an outer member employed in a ballpoint pen of the second exemplary embodiment, and  FIG. 7B  is a vertical cross-section thereof. 
           [0035]      FIG. 8A  is a perspective view of a joint and an outer member employed in a ballpoint pen of the second exemplary embodiment, and  FIG. 8B  is a vertical cross-section thereof. 
           [0036]      FIG. 9  is a perspective view of a tip shaft of a ballpoint pen of the second exemplary embodiment. 
           [0037]      FIG. 10A  is a front view of a ballpoint pen of a third exemplary embodiment of the present invention, and  FIG. 10B  is a vertical cross-section thereof. 
           [0038]      FIG. 11  is a vertical cross-section of a tip portion of a ballpoint pen of the third exemplary embodiment. 
           [0039]      FIG. 12  is a vertical cross-section of a shaft body and a joint employed in a ballpoint pen of the third exemplary embodiment. 
           [0040]      FIG. 13  is a perspective view of a tip shaft of a ballpoint pen of the third exemplary embodiment. 
           [0041]      FIG. 14A  is a front view of a ballpoint pen of a fourth exemplary embodiment of the present invention, and  FIG. 14B  is a vertical cross-section thereof. 
           [0042]      FIG. 15  is a vertical cross-section of a tip portion of a ballpoint pen of the fourth exemplary embodiment. 
           [0043]      FIG. 16A  is a perspective view of an outer member employed in a ballpoint pen of the fourth exemplary embodiment, and  FIG. 16B  is a vertical cross-section thereof. 
           [0044]      FIG. 17  is a perspective view of a tip shaft of ballpoint pen of the fourth exemplary embodiment. 
           [0045]      FIG. 18A  is a front view of a ballpoint pen of a fifth exemplary embodiment of the present invention, and  FIG. 18B  is a vertical cross-section thereof. 
           [0046]      FIG. 19  is a vertical cross-section of a tip portion of a ballpoint pen of the fifth exemplary embodiment. 
           [0047]      FIG. 20A  is a perspective view of a joint employed in a ballpoint pen of the fifth exemplary embodiment, and  FIG. 20B  is a vertical cross-section thereof. 
           [0048]      FIG. 21  is a perspective view of a tip shaft of a ballpoint pen of the fifth exemplary embodiment. 
           [0049]      FIG. 22A  is a front view of a ballpoint pen of a sixth exemplary embodiment of the present invention, and  FIG. 22B  is a vertical cross-section thereof. 
           [0050]      FIG. 23  is a vertical cross-section of a tip portion of a ballpoint pen of the sixth exemplary embodiment. 
           [0051]      FIG. 24A  is a perspective view of the front of a shaft body employed in a ballpoint pen of the sixth exemplary embodiment, and  FIG. 24B  is a vertical cross-section thereof. 
           [0052]      FIG. 25A  is a perspective view of a joint employed in a ballpoint pen of the sixth exemplary embodiment, and  FIG. 25B  is a vertical cross-section thereof. 
           [0053]      FIG. 26  is a perspective view of a tip shaft of a ballpoint pen of the sixth exemplary embodiment. 
           [0054]      FIG. 27  illustrates a character written with a ballpoint pen according to the present invention, and characters written with conventional writing implements. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0055]    Explanation follows regarding embodiments of the present invention, split into a first to a sixth exemplary embodiments, with reference to the drawings. Note that in the present specification, “front” with reference to a ballpoint pen  1  and its configuring components means a tip side with a writing ball  30  as the tip of the ballpoint pen  1 , and “rear” is the opposite side thereto. 
       First Exemplary Embodiment 
       [0056]      FIG. 1A  illustrates an external appearance of a ballpoint pen  1  according to a first exemplary embodiment. As illustrated in  FIG. 1B  and  FIG. 2 , the ballpoint pen  1  includes a ballpoint pen tip  20 , including a writing ball  30  and a holder  21  that retains the writing ball  30  with a swaged section  23  swaged at its tip end, an ink supply section  40  that supplies ink to the holder  21  of the ballpoint pen tip  20 , and a shaft  10  that internally houses the ink supply section  40 . 
         [0057]    As illustrated in  FIG. 1B , the shaft  10  comprises a shaft body  11  equipped with an ink housing section  13 , and a tip shaft  12  provided at a tip of the shaft body  11 . The tip shaft  12  is configured from a joint  50  fixed to a tip portion of the shaft body  11 , and an outer member  60  fixed to the joint  50 . An internal joint  14  for connecting the ink supply section  40  and the ballpoint pen tip  20  together is installed inside the tip shaft  12 . The ink housing section  13  is filled with ink, not illustrated in the drawings. 
         [0058]    As illustrated in  FIG. 1B , the ink supply section  40  includes a substantially cylindrical shaped collector  41  with plural fins formed around its external periphery, a tip holding portion  42  that is formed with a reduced diameter at a tip of the collector  41 , and a tip piece  44  formed from a rubber elastic material and mounted to a tip of the tip holding portion  42 . A rear end portion of the collector  41  contacts the ink housing section  13 . As illustrated in  FIG. 2 , the tip holding portion  42  is fitted into a rear internal portion of the tip piece  44 , and the internal joint  14  is fitted into a front internal portion of the tip piece  44 . A collector core  43  is formed from rod shaped polyester fibers, with its rear end side projecting out inside the ink housing section  13  (see  FIG. 1B ), with its central portion axially passing through the collector  41 , the tip holding portion  42 , and the tip piece  44 , and with its tip side being inserted through from a rear end portion of the internal joint  14  to a position approximately halfway along the internal joint  14 . 
         [0059]    As illustrated in  FIG. 2 , the ballpoint pen tip  20  includes the cylindrical shaped holder  21 , and the writing ball  30  retained by the holder  21 . A tip end side of the holder  21  is formed with a substantially circular conical shaped tapered portion  22  tapering toward the tip end, and with the swaged section  23 , where a tip end edge of the tapered portion  22  is pressed inwards and reduced in diameter. A tip end portion of the writing ball  30  that is gripped inside the tapered portion  22  is exposed through a tip end edge of the swaged section  23 . The holder  21  may be formed by processing a pipe member made from a metal such as stainless steel, or from a resin such as polyacetal. A rod shaped central core  25  is inserted inside the holder  21  and projects out from a rear end portion of the holder  21 . The central core  25  is, similarly to the collector core  43 , formed from polyester fibers. A rear end of the central core  25  is fitted into a tip end portion of the collector core  43 , and a tip end of the central core  25  reaches just behind the writing ball  30 . The central core  25  sucks in ink that has permeated into the collector core  43 , and supplies the ink to the writing ball  30 . The ballpoint pen tip  20  is retained by the internal joint  14  in a state in which approximately two-thirds of a rear end part of the ballpoint pen tip  20  is fitted into the internal joint  14 . 
         [0060]    The collector core  43  and the central core  25  are formed by selecting polyester fibers of appropriate porosity and surface profile according to characteristics of the ink being employed, such as the viscosity. 
         [0061]    The joint  50  is a component made from a synthetic resin, and configured with a cylindrical shaped joint fixing portion  51 , and a substantially circular conical shaped joint tapered portion  52  continuously provided to the joint fixing portion  51 . A hole is formed through from a rear end toward a tip end of the joint  50 , with a rear insertion hole  53  provided at an inner face of the joint fixing portion  51 , a central insertion hole  54  with a smaller diameter than that of the rear insertion hole  53  provided at an inner face in the vicinity of a center of the joint tapered portion  52 , and a front insertion hole  55  with a diameter substantially the same as that of the central insertion hole  54  provided at the inner face in the vicinity of a tip end of the joint tapered portion  52 . 
         [0062]    The joint  50  is a component formed by double molding, and, as illustrated in  FIG. 3A  and  FIG. 3B , the joint  50  is formed such that a rear half  16 , as a primary molding body, and a front half  15 , as a secondary molding body, are interdigitated with each other in a serrated pattern. The rear half  16  is configured by a portion from a rear end of the joint fixing portion  51  over approximately one-third of a rear side of the front insertion hole  55 , and by rear half indentations  16   b  spanning from the tip end of that portion to substantially the center of the joint tapered portion  52  at eight evenly disposed external peripheral locations. Rear half projections  16   a  are formed between adjacent of the rear half indentations  16   b . The front half  15  is configured by a ring shaped portion  15   b  that is a portion from the tip end of the joint tapered portion  52  over approximately two-thirds of a front side of the front insertion hole  55 , and by front half projections  15   a  that extend rearward from the ring shaped portion  15   b , so as to correspond to the rear half indentations  16   b . The front half  15  and the rear half  16  are integrated together by joining such that the rear half projections  16   a , and the front half projections  15   a  for fitting into the rear half indentations  16   b , are mutually aligned so as to interdigitate with each other. 
         [0063]    In order to obtain flexing, although it is desirable to employ a thermoplastic elastomer for the front half  15 , as the secondary molding body, the same material may be employed as that of the rear half  16 , as the primary molding body. 
         [0064]    As illustrated in  FIG. 1B  and  FIG. 2 , the ink supply section  40  and the internal joint  14  that fits into the ink supply section  40  are inserted into the joint  50  from its rear. Herein, the tip piece  44  fits into the rear insertion hole  53 , and the internal joint  14  is inserted into the central insertion hole  54 . The joint  50  is fixed to the shaft body  11  by the joint fixing portion  51  fitting into an inner face in the vicinity of a tip end of the shaft body  11 . 
         [0065]    The outer member  60  is, as illustrated in  FIG. 2 , a synthetic resin component configured by a cylindrical shaped outer fixing portion  61 , and a substantially circular conical shaped outer tapered portion  62  continuously provided at the outer fixing portion  61 . A beveled outer tip portion  66  is provided at a tip end of the outer tapered portion  62 . A hole is formed through from a rear end toward a tip end of the outer member  60 , with a rear insertion hole  63  provided at an inner face of the outer fixing portion  61 , and a front insertion hole  64  of a smaller diameter than the rear insertion hole  63  provided at an inner face in the vicinity of the tip end of the outer tapered portion  62 . The outer fixing portion  61  is fixed to the joint  50  by being fitted into the front insertion hole  55  of the joint  50 . The outer member  60  covers the ballpoint pen tip  20 . Herein, a tip end portion of the internal joint  14  is inserted into the rear insertion hole  63 , and the ballpoint pen tip  20  projecting out from the internal joint  14  is fitted into the front insertion hole  64 . As illustrated in  FIG. 4 , only the writing ball  30 , the swaged section  23  covering the writing ball  30 , and the outer tip portion  66  are exposed in the vicinity of the tip end of the outer member  60 , in a placement such that when the writing ball  30  and the outer tip portion  66  both contact a writing surface at the same time, a space is generated at a portion surrounded by the writing surface, the writing ball  30 , the swaged section  23 , and the outer tip portion  66 . 
         [0066]    The ballpoint pen  1  has a structure in which the joint  50  readily flexes by deformation in the vicinity of a joint portion between the front half  15  and the rear half  16 . This enables the outer member  60  to be tilted from a central axis of the shaft body  11  according to the force applied during writing. This enables a writing sensation akin to that of a fountain pen to be obtained. 
         [0067]    If the writing ball  30  and the outer tip portion  66  contact the writing surface due to the outer member  60  tilting from the central axis of the shaft body  11 , ink adhering to a surface of the writing ball  30 , and ink flowing out from a non-illustrated ball housing accompanying rotation of the writing ball  30 , spreads out under capillary action into the space surrounded by the writing surface, the writing ball  30 , the swaged section  23 , and the outer tip portion  66 . This enables a thicker line to be drawn than a line drawn by the writing ball  30 . Namely, the thickness of line drawn can be varied because it is possible to finely adjust the angle of the writing tip end with respect to the writing surface by flexing of the joint  50 . 
       Second Exemplary Embodiment 
       [0068]      FIG. 5A  illustrates an external appearance of a ballpoint pen  1  according to a second exemplary embodiment. The second exemplary embodiment is one in which a joint  50  and an outer member  60  are integrally formed. Note that the second exemplary embodiment differs from the first exemplary embodiment in a structure of a tip shaft  12 , but is otherwise similar to the first exemplary embodiment, and so explanation will only be given to different points. 
         [0069]    The joint  50  and the outer member  60  are components made from synthetic resin. As illustrated in  FIG. 6 , the joint  50  is configured by a cylindrical shaped joint fixing portion  51 , and a truncated circular conical shaped joint tapered portion  52  continuously provided to the joint fixing portion  51 . The outer member  60  is juxtaposed to the joint tapered portion  52 , and is configured by a substantially circular conical shaped outer tapered portion  62  having a larger taper angle than the joint tapered portion  52 . A hole is formed through from a rear end toward a tip end of the joint  50 , with a rear insertion hole  53  provided at an inner face of the joint fixing portion  51 , and a central insertion hole  54  of a smaller diameter than the rear insertion hole  53  provided at an inner face in the vicinity of a tip end of the joint tapered portion  52 . A hole continuing from the joint  50  is formed in the outer member  60 , with a rear insertion hole  63  of a smaller diameter than the central insertion hole  54  is provided at an inner face in the vicinity of a rear end of the outer tapered portion  62 , and a front insertion hole  64  of a smaller diameter than the rear insertion hole  63  is provided at the inner face in the vicinity of a tip end of the outer tapered portion  62 . A beveled outer tip portion  66  is provided at the tip end of the outer tapered portion  62 . 
         [0070]    Moreover, the joint  50  and the outer member  60  are components formed by double molding, and are formed such that a rear half  16 , as a primary molding body, and a front half  15 , as a secondary molding body, are interdigitated with each other in a serrated pattern. As illustrated in  FIG. 7A  and  FIG. 7B , the rear half  16  is configured by a portion from a rear end of the joint fixing portion  51  over approximately half of a rear side of the joint tapered portion  52 , by rear half projections  16   a  extending from a position at substantially half the way along the joint tapered portion  52  toward the tip end of the joint tapered portion  52  at three evenly disposed locations with respect to a central axis, and by a ring portion  16   c  formed in a ring shape at a tip end of the rear half projections  16   a . As illustrated in  FIG. 8A  and  FIG. 8B , the front half  15  is configured by the outer tapered portion  62  and by front half projections  15   a  that extend from the vicinity of a rear end of the outer tapered portion  62  toward a position substantially half way along the joint tapered portion  52 , at three evenly disposed locations with respect to the central axis. The front half  15  and the rear half  16  are integrated together by joining together such that the rear half projections  16   a , and the front half projections  15   a  are mutually aligned so as to interdigitate with each other. The ring portion  16   c  is inserted inside the front half  15  in a configuration such that the rear half  16  does not fall out from the front half  15  even though the front half  15  and the rear half  16  are formed by double molding without being adhered to each other. 
         [0071]    Note that flexing of the front half  15 , as the secondary molding body, can be obtained even when molded from similar material to that of the rear half  16 , as the primary molding body. 
         [0072]    As illustrated in  FIG. 5B  and  FIG. 6 , the ink supply section  40  and an internal joint  14  that fits into the ink supply section  40  are inserted into the joint  50  from its rear. Herein, a tip piece  44  fits into the rear insertion hole  53 , and the internal joint  14  is inserted into the central insertion hole  54  and the rear insertion hole  63 . A ballpoint pen tip  20  that projects out from the internal joint  14  is inserted into the front insertion hole  64 . The joint  50  is fixed to a shaft body  11  by the joint fixing portion  51  fitting into an inner face in the vicinity of a tip end of the shaft body  11 . 
         [0073]    A tip end portion of the outer member  60  covers the ballpoint pen tip  20 . As illustrated in  FIG. 9 , only a writing ball  30 , a swaged section  23  covering the writing ball  30 , and the outer tip portion  66  are exposed in the vicinity of a tip end of the outer member  60 , in a placement such that when the writing ball  30  and the outer tip portion  66  both contact a writing surface at the same time, a space is generated at a portion surrounded by the writing surface, the writing ball  30 , the swaged section  23 , and the outer tip portion  66 . 
         [0074]    The ballpoint pen  1  has a structure in which the joint  50  and the outer member  60 , which are integrally formed, readily flex by deformation in the vicinity of a joint portion between the front half  15  and the rear half  16 . This enables the front half  15  to be tilted from a central axis of the shaft body  11  according to the force applied during writing. This enables a writing sensation akin to that of a fountain pen to be obtained. 
         [0075]    Moreover, if the writing ball  30  and the outer tip portion  66  contact the writing surface due to the outer member  60  being tilted from the central axis of the shaft body  11 , ink adhering to a surface of the writing ball  30 , and ink flowing out from a non-illustrated ball housing accompanying rotation of the writing ball  30 , spreads out under capillary action into the space surrounded by the writing surface, the writing ball  30 , the swaged section  23 , and the outer tip portion  66 . This enables a thicker line to be drawn than a line drawn by the writing ball  30 . Namely, the thickness of line drawn can be varied because it is possible to finely adjust the angle of the writing tip end with respect to the writing surface by flexing of the joint  50 . 
       Third Exemplary Embodiment 
       [0076]      FIG. 10A  illustrates an external appearance of a ballpoint pen  1  according to a third exemplary embodiment. In the third exemplary embodiment, the joint  50  and the shaft body  11  are integrally formed. Note that the third exemplary embodiment differs from the first exemplary embodiment in a structure of a tip shaft  12 , but is otherwise similar to the first exemplary embodiment, and so explanation will only be given to different points. 
         [0077]    The joint  50  and the shaft body  11  are components made from synthetic resin and, as illustrated in  FIG. 11 , are configured by a shaft tapered portion  17  formed at a tip end portion of the shaft body  11 , and by a substantially circular conical shaped joint tapered portion  52  juxtaposed to the shaft tapered portion  17  and having a larger taper angle than the shaft tapered portion  17 . A central insertion hole  54  is formed at an inner face of the joint tapered portion  52 . 
         [0078]    Moreover, the joint  50  and the shaft body  11  are components formed by double molding, and, as illustrated in  FIG. 12  and  FIG. 13 , a rear half  16 , as a primary molding body, and a front half  15 , as a secondary molding body, are interdigitated with each other in a serrated pattern. The rear half  16  is configured by a portion of the shaft body  11  behind the shaft tapered portion  17 , by a tube shaped connection portion  16   d  continuously provided at a tip end of the shaft tapered portion  17 , and by rear half indentations  16   b  spanning over approximately one-fifth of a front of the shaft body  11  from the tip end of the shaft tapered portion  17  at four evenly disposed peripheral locations. Rear half projections  16   a  are configured between adjacent of the rear half indentations  16   b . The front half  15  is configured by the joint tapered portion  52 , and by front half projections  15   a  that extend rearward from a rear end of the joint tapered portion  52 , and that are formed so as to correspond to the rear half indentations  16   b . The front half  15  and the rear half  16  are integrated together by joining together such that the rear half projections  16   a , and the front half projections  15   a  accommodated in the rear half indentations  16   b  are mutually aligned so as to interdigitate with each other. 
         [0079]    Note that, in order to obtain flexing, the front half  15 , as the secondary molding body, preferably employs a rubber elastic material such as a thermoplastic elastomer, but a similar material may be employed to that of the rear half  16 , as the primary molding body, as long as it is a material of low hardness. 
         [0080]    As illustrated in  FIG. 10B  and  FIG. 11 , an ink supply section  40  and an internal joint  14  that fits into the ink supply section  40  are inserted into the joint  50  from its rear. Herein, the internal joint  14  is inserted into the central insertion hole  54 . 
         [0081]    An outer member  60  is, as illustrated in  FIG. 11 , a component made from synthetic resin and configured by a cylindrical shaped outer fixing portion  61  and a substantially circular conical shaped outer tapered portion  62  continuously provided to the outer fixing portion  61 . A beveled outer tip portion  66  is provided at a tip end of the outer tapered portion  62 . A hole is formed through from a rear end toward a tip end of the outer member  60 , with a rear insertion hole  63  provided at an inner face of the outer fixing portion  61 , and a front insertion hole  64  of a smaller diameter than the rear insertion hole  63  provided at an inner face in the vicinity of the tip end of the outer tapered portion  62 . The outer fixing portion  61  is fixed to the joint  50  by fitting into the central insertion hole  54  of the joint  50 . The outer member  60  covers a ballpoint pen tip  20 . Herein, a tip end portion of the internal joint  14  is inserted into the rear insertion hole  63 , and the ballpoint pen tip  20  projecting out from the internal joint  14  is fitted into the front insertion hole  64 . As illustrated in  FIG. 13 , only a writing ball  30 , a swaged section  23  covering the writing ball  30 , and the outer tip portion  66  are exposed in the vicinity of the tip end of the outer member  60 , in a placement such that when the writing ball  30  and the outer tip portion  66  both contact a writing surface at the same time, a space is generated at a portion surrounded by the writing surface, the writing ball  30 , the swaged section  23 , and the outer tip portion  66 . 
         [0082]    The ballpoint pen  1  has a structure in which the front of the shaft body  11  and the joint  50  readily flex by deformation in the vicinity of a joint portion between the front half  15  and the rear half  16 . This enables the outer member  60  to be tilted from a central axis of the shaft body  11  according to the force applied during writing. This enables a writing sensation akin to that of a fountain pen to be obtained. 
         [0083]    Moreover, if the writing ball  30  and the outer tip portion  66  contact the writing surface due to the outer member  60  being tilted from the central axis of the shaft body  11 , ink adhering to the surface of the writing ball  30 , and ink flowing out from a non-illustrated ball housing accompanying rotation of the writing ball  30 , spreads out under capillary action into the space surrounded by the writing surface, the writing ball  30 , the swaged section  23 , and the outer tip portion  66 . This enables a thicker line to be drawn than a line drawn by the writing ball  30 . Namely, the thickness of line drawn can be varied because it is possible to finely adjust the angle of the writing tip end with respect to the writing surface by flexing of the joint  50 . 
       Fourth Exemplary Embodiment 
       [0084]      FIG. 14A  illustrates an external appearance of a ballpoint pen  1  according to a fourth exemplary embodiment. The ballpoint pen  1  is, as illustrated in  FIG. 14B  and  FIG. 15 , equipped with a ballpoint pen tip  20  including a writing ball  30  and a holder  21  retaining the writing ball  30  with a swaged section  23  swaged at its tip end, an ink supply section  40  that supplies ink to the holder  21  of the ballpoint pen tip  20 , and a shaft  10  that internally houses the ink supply section  40 . 
         [0085]    As illustrated in  FIG. 14B , the shaft  10  is configured by a shaft body  11  equipped with an ink housing section  13 , and a tip shaft  12  provided at a tip end of the shaft body  11 . The tip shaft  12  comprises a joint  50  fixed at the tip end of the shaft body  11 , and an outer member  60  fixed to the joint  50 . An internal joint  14  connecting the ink supply section  40  and the ballpoint pen tip  20  together is installed inside the tip shaft  12 . Moreover, non-illustrated ink fills the ink housing section  13 . 
         [0086]    As illustrated in  FIG. 14B , the ink supply section  40  includes a substantially tube shaped collector  41  with plural fins formed around its external periphery, a tip holding portion  42  that is formed with reduced diameter at a tip of the collector  41 , and a tip piece  44  formed from a rubber elastic material and mounted to a tip of the tip holding portion  42 . A rear end portion of the collector  41  contacts the ink housing section  13 . As illustrated in  FIG. 15 , the tip holding portion  42  is fitted into a rear internal portion of the tip piece  44 , and the internal joint  14  is fitted into a front internal portion of the tip piece  44 . A collector core  43  is formed from rod shaped polyester fibers, with a rear end side of the collector core  43  projecting out inside the ink housing section  13  (see  FIG. 14B ), with a central portion of the collector core  43  axially passing through the collector  41 , the tip holding portion  42 , and the tip piece  44 . A tip side of the collector core  43  inserted through from a rear end portion of the internal joint  14  to a position approximately halfway along the internal joint  14 . 
         [0087]    As illustrated in  FIG. 15 , the ballpoint pen tip  20  includes the cylindrical shaped holder  21 , and the writing ball  30  retained by the holder  21 . A tip end side of a holder  21  is formed with a substantially circular conical shaped tapered portion  22  tapering toward its tip end, and with the swaged section  23 , where a tip end edge of the tapered portion  22  is pressed inwards and reduced in diameter. A tip end portion of the writing ball  30  that is gripped inside the tapered portion  22  is exposed through a tip end edge of the swaged section  23 . The holder  21  may be formed by processing a pipe member made from a metal such as stainless steel, or from a resin such as polyacetal. A rod shaped central core  25  is inserted inside the holder  21  and projects out from a rear end portion of the holder  21 . The central core  25  is, similarly to the collector core  43 , formed from polyester fibers. A rear end of the central core  25  is fitted into a tip end portion of the collector core  43 , and a tip end of the central core  25  reaches just behind the writing ball  30 . The central core  25  sucks in ink that has permeated into the collector core  43 , and supplies the ink to the writing ball  30 . The ballpoint pen tip  20  is retained by the internal joint  14  in a state in which approximately two-thirds of a rear end side of the ballpoint pen tip  20  is fitted into the internal joint  14 . 
         [0088]    The collector core  43  and the central core  25  are formed by selecting polyester fibers of appropriate porosity and surface profile according to characteristics of the ink being employed, such as the viscosity. 
         [0089]    The joint  50  is a component made from a synthetic resin, and is configured with a cylindrical shaped joint fixing portion  51 , and a substantially circular conical shaped joint tapered portion  52  provided continuously to the joint fixing portion  51 . As illustrated in  FIG. 15 , a hole is formed through from a rear end toward a tip end of the joint  50 , with a rear insertion hole  53  provided at an inner face of the joint fixing portion  51 , and a central insertion hole  54  with a smaller diameter than that of the rear insertion hole  53  provided at an inner face in the vicinity of a center of the joint tapered portion  52 . A front insertion hole  55  with a diameter substantially the same as that of the central insertion hole  54  is provided at the inner face in the vicinity of a tip end of the joint tapered portion  52 . Moreover, as illustrated in  FIG. 17 , openings  56  are disposed evenly at three locations at a tip end edge of the joint  50 . 
         [0090]    As illustrated in  FIG. 14B  and  FIG. 15 , the ink supply section  40  and the internal joint  14  that fits into the ink supply section  40  are inserted into the joint  50  from its rear. Herein, the tip piece  44  fits into the rear insertion hole  53 , and the internal joint  14  is inserted into the central insertion hole  54 . The joint  50  is fixed to the shaft body  11  by the joint fixing portion  51  fitting into an inner face in the vicinity of the tip end of the shaft body  11 . 
         [0091]    The outer member  60  is, as illustrated in  FIG. 15 ,  FIG. 16A , and  FIG. 16B , a synthetic resin component configured by a cylindrical shaped outer fixing portion  61 , and a substantially circular conical shaped exposed portion  60   a  occupying a tip end side from the outer fixing portion  61  and being externally visible. A tip end side of the exposed portion  60   a  is formed as an outer tapered portion  62 , and a beveled outer tip portion  66  is provided to a tip end of the outer tapered portion  62 . Three projections  65  spanning from a rear end of the outer tapered portion  62  to a tip end of the outer fixing portion  61  are evenly placed in a pattern radiating out from a central axis at a rear end side of the exposed portion  60   a . As illustrated in  FIG. 17 , the projections  65  are inserted inside corresponding openings  56  of the joint  50 . Moreover, at positions approximately one-third of the way from a rear end side of the outer tapered portion  62 , slits  19  are formed at two locations each at portions on either side of the projections  65  in a pattern radiating out from the central axis in a total of six locations. A hole is formed through from a rear end toward a tip end of the outer member  60 , with a rear insertion hole  63  provided at an inner face of the outer fixing portion  61 , and a front insertion hole  64  of a smaller diameter than the rear insertion hole  63  provided at an inner face in the vicinity of the tip end of the outer tapered portion  62 . The outer fixing portion  61  is fixed to the joint  50  by being fitted into the front insertion hole  55  of the joint  50 . The outer member  60  covers the ballpoint pen tip  20 . Herein, a tip end portion of the internal joint  14  is inserted into the rear insertion hole  63 , and the ballpoint pen tip  20  projecting out from the internal joint  14  is fitted into the front insertion hole  64 . As illustrated in  FIG. 17 , only the writing ball  30 , the swaged section  23  covering the writing ball  30 , and the outer tip portion  66  are exposed in the vicinity of the tip end of the outer member  60 , in a placement such that when the writing ball  30  and the outer tip portion  66  both contact a writing surface at the same time, a space is generated at a portion surrounded by the writing surface, the writing ball  30 , the swaged section  23 , and the outer lip portion  66 . 
         [0092]    The ballpoint pen  1  has a structure that readily flexes in the vicinity of the slits  19 , thereby enabling a tip end portion of the outer member  60  to be tilted from the central axis of the shaft body  11  according to the force applied during writing. This enables a writing sensation akin to that of a fountain pen to be obtained. 
         [0093]    If the writing ball  30  and the outer tip portion  66  contact the writing surface due to the tip end portion of the outer member  60  tilting from the central axis of the shaft body  11 , ink adhering to a surface of the writing ball  30 , and ink flowing out from a non-illustrated ball housing accompanying rotation of the writing ball  30 , spreads out under capillary action into the space surrounded by the writing surface, the writing ball  30 , the swaged section  23 , and the outer tip portion  66 . This enables a thicker line to be drawn than a line drawn by the writing ball  30 . Namely, the thickness of line drawn can be varied because it is possible to finely adjust the angle of the writing tip end with respect to the writing surface by flexing in the vicinity of the slits  19 . 
         [0094]    Moreover, by flexing in the vicinity of the slits  19  according to the force applied to the writing tip, the projections  65  on an external peripheral face move in the flexed direction inside the openings  56  into which they are inserted. Thus flexing in the vicinity of the slits  19  is visible to a user of the ballpoint pen  1  from the movement of the projections  65 . 
       Fifth Exemplary Embodiment 
       [0095]      FIG. 18A  illustrates an external appearance of a ballpoint pen  1  according to a fifth exemplary embodiment. In the fifth exemplary embodiment there are slits  19  provided in a joint  50  at a tip shaft  12 . The fifth exemplary embodiment differs from the fourth exemplary embodiment in a structure of the tip shaft  12 , but is otherwise similar to the fourth exemplary embodiment, and so explanation will only be given to different points. 
         [0096]    As illustrated in  FIG. 19 , the joint  50  is a component made from a synthetic resin, and is configured with a cylindrical shaped joint fixing portion  51 , and a substantially circular conical shaped joint tapered portion  52  continuously provided to the joint fixing portion  51 . A hole is formed through from a rear end toward a tip end of the joint  50 , with a rear insertion hole  53  provided at an inner face of the joint fixing portion  51 , and a central insertion hole  54  with a smaller diameter than that of the rear insertion hole  53  provided at an inner face in the vicinity of a center of the joint tapered portion  52 . A front insertion hole  55  with a diameter slightly smaller than that of the central insertion hole  54  is provided at the inner face in the vicinity of a tip end of the joint tapered portion  52 . Moreover, as illustrated in  FIG. 20A ,  FIG. 20B , and  FIG. 21 , nine slits  19  spanning from a tip end of the joint  50  to the vicinity of the center of the joint tapered portion  52  are evenly disposed in a pattern radiating out from a central axis. In the vicinity of the central insertion hole  54 , the slits  19  pierce through up to an internal face of the central insertion hole  54 . 
         [0097]    As illustrated in  FIG. 18B  and  FIG. 19 , an ink supply section  40  and an internal joint  14  that fits into the ink supply section  40  are inserted into the joint  50  from its rear. Herein, a tip piece  44  fits into the rear insertion hole  53 , and the internal joint  14  is inserted into the central insertion hole  54 . The joint  50  is fixed to a shaft body  11  by the joint fixing portion  51  fitting into an inner face in the vicinity of a tip end of the shaft body  11 . 
         [0098]    As illustrated in  FIG. 19  and  FIG. 21 , an outer member  60  is a component made from synthetic resin and configured by a cylindrical shaped outer fixing portion  61  and a substantially circular conical shaped outer tapered portion  62  continuously provided to the outer fixing portion  61 . A beveled outer tip portion  66  is provided at a tip end of the outer tapered portion  62 . A hole is formed through from a rear end toward a tip end of the outer member  60 , with a rear insertion hole  63  provided at an inner face of the outer fixing portion  61 , and a front insertion hole  64  of a smaller diameter than the rear insertion hole  63  provided at an inner face in the vicinity of the tip end of the outer tapered portion  62 . The outer fixing portion  61  is fixed to the joint  50  by being fitted into the front insertion hole  55  of the joint  50 . The outer member  60  covers a ballpoint pen tip  20 . Herein, the tip end portion of the internal joint  14  is inserted into the rear insertion hole  63 , and the ballpoint pen tip  20  projecting out from the internal joint  14  is fitted into the front insertion hole  64 . As illustrated in  FIG. 21 , only a writing ball  30 , a swaged section  23  covering the writing ball  30 , and the outer tip portion  66  are exposed in the vicinity of the tip end of the outer member  60 , in a placement such that when the writing ball  30  and the outer tip portion  66  both contact a writing surface at the same time, a space is generated at a portion surrounded by the writing surface, the writing ball  30 , the swaged section  23 , and the outer tip portion  66 . 
         [0099]    The ballpoint pen  1  has a structure readily flexing in the vicinity of the slits  19 . This enables the outer member  60  to be tilted from a central axis of the shaft body  11  according to the force applied during writing. This enables a writing sensation akin to that of a fountain pen to be obtained. 
         [0100]    If the writing ball  30  and the outer tip portion  66  contact the writing surface due to the outer member  60  tilting from the central axis of the shaft body  11 , ink adhering to a surface of the writing ball  30 , and ink flowing out from a non-illustrated ball housing accompanying rotation of the writing ball  30 , spreads out under capillary action into the space surrounded by the writing surface, the writing ball  30 , the swaged section  23 , and the outer tip portion  66 . This enables a thicker line to be drawn than a line drawn by the writing ball  30 . Namely, the thickness of line drawn can be varied because it is possible to finely adjust the angle of the writing tip end with respect to the writing surface by flexing in the vicinity of the slits  19 . 
       Sixth Exemplary Embodiment 
       [0101]      FIG. 22A  illustrates an external appearance of a ballpoint pen  1  according to a sixth exemplary embodiment. In the sixth exemplary embodiment, slits  19  are provided in a tip shaft  12  inside a joint  50 . The sixth exemplary embodiment differs from the fourth exemplary embodiment in the structure of the tip shaft  12 , but is otherwise similar to the fourth exemplary embodiment, and so explanation will only be given to different points. 
         [0102]    As illustrated in  FIG. 22A ,  FIG. 24A  and  FIG. 24B , cutouts  18  are formed in a reduced diameter portion at a front of a shaft body  11 , from a tip end of the reduced diameter portion to approximately two-thirds of the way along the reduced diameter portion. 
         [0103]    As illustrated in  FIG. 25A  and  FIG. 25B , the joint  50  is a component made from a synthetic resin, and is configured with a cylindrical shaped joint cylinder  52   b , and substantially triangular shaped projections  57  evenly disposed at eight locations on an outer peripheral face of the joint cylinder  52   b  and formed axially projecting such that a portion of each of the projections  57  projects out to a rear of the joint cylinder  52   b . Slits  19  are formed from a rear end of the projections  57  to approximately one-third of a rear side of the joint  50  in a pattern radiating out from the central axis, such that gaps arise between the projections  57  and the joint cylinder  52   b . A hole is formed through from a rear end toward a tip end of the joint  50 , with a rear insertion hole  53  provided at an inner face at the rear of the joint cylinder  52   b , and a front insertion hole  55  of the same diameter as the rear insertion hole  53  provided at the inner face at a front of the joint cylinder  52   b.    
         [0104]    As illustrated in  FIG. 22B  and  FIG. 23 , an internal joint  14  that fits into the ink supply section  40  is inserted into the joint  50  from its rear. The joint  50  is fixed to the shaft body  11  by the projections  57  fitting into the cutouts  18  of the shaft body  11 . 
         [0105]    As illustrated in  FIG. 23  and  FIG. 26 , an outer member  60  is a component made from synthetic resin and configured by a cylindrical shaped outer fixing portion  61  and a substantially circular conical shaped outer tapered portion  62  continuously provided to the outer fixing portion  61 . A beveled outer tip portion  66  is provided at a tip end of the outer tapered portion  62 . A hole is formed through from a rear end toward a tip end of the outer member  60 , with a rear insertion hole  63  provided at an inner face of the outer fixing portion  61 , and a front insertion hole  64  of a smaller diameter than the rear insertion hole  63  provided at an inner face in the vicinity of the tip end of the outer tapered portion  62 . The outer fixing portion  61  is fixed at the joint  50  by being inserted into the front insertion hole  55  of the joint  50 . The outer member  60  covers a ballpoint pen tip  20 . Herein, a tip end portion of the internal joint  14  is inserted into the rear insertion hole  63 , and the ballpoint pen tip  20  projecting out from the internal joint  14  is fitted into the front insertion hole  64 . As illustrated in  FIG. 26 , only a writing ball  30 , a swaged section  23  covering the writing ball  30 , and the outer tip portion  66  are exposed in the vicinity of the tip end of the outer member  60 , in a placement such that when the writing ball  30  and the outer tip portion  66  both contact a writing surface at the same time, a space is generated at a portion surrounded by the writing surface, the writing ball  30 , the swaged section  23 , and the outer tip portion  66   
         [0106]    The ballpoint pen  1  is configured with a structure in which, due to the slits  19 , the projections  57  readily flex to front and rear, and to the left and right, with respect to the central axis of the shaft body  11 . This enables the outer member  60  to be tilted from the central axis of the shaft body  11  according to the force applied during writing. This enables a writing sensation akin to that of a fountain pen to be obtained. 
         [0107]    Moreover, if the writing ball  30  and the outer tip portion  66  contact the writing surface due to the outer member  60  tilting from the central axis of the shaft body  11 , ink adhering to a surface of the writing ball  30 , and ink flowing out from a non-illustrated ball housing accompanying rotation of the writing ball  30 , spreads out under capillary action into the space surrounded by the writing surface, the writing ball  30 , the swaged section  23 , and the outer tip portion  66 . This enables a thicker line to be drawn than a line drawn by the writing ball  30 . Namely, the thickness of line drawn can be varied because it is possible to finely adjust the angle of the writing tip end with respect to the writing surface by flexing in the vicinity of the slits  19 . 
       Comparative Examples to Other Writing Implements 
       [0108]      FIG. 27  illustrates calligraphy of writing with a ballpoint pen, a felt-tip pen, a fountain pen, and the ballpoint pen  1  according to the present invention. The calligraphy of writing with the ballpoint pen  1  according to the present invention enables easier and higher quality writing of a “stop” α at an end of a stroke, an “upward tick” β, and a “sweeping stroke” γ compared to those with a ballpoint pen, a felt-tip pen, or a fountain pen. 
         [0109]    Thus in this manner, in the first, second, and third exemplary embodiments described above, the outer member  60  can be flexed by deformation in the vicinity of the joint between the front half  15  and the rear half  16 , and moreover in the fourth, fifth, and sixth exemplary embodiments described above, the outer member  60  can be flexed due to the slits  19 , enabling the writing sensation akin to that of a fountain pen to be obtained according to the force applied during writing. 
         [0110]    Moreover, the configuration of the ballpoint pen tip  20  and the outer member  60  makes it possible to draw lines of different thicknesses using a single writing tip according to the angle of the ballpoint pen tip. Thus because it is possible to finely adjust the angle of the ballpoint pen tip with respect to the writing surface according to the force applied during writing, the thickness of line drawn is variable markedly, enabling an improvement in the expressiveness of writing to be achieved. 
       INDUSTRIAL APPLICABILITY 
       [0111]    The present invention is applicable to a writing implement such as a ballpoint pen.