Abstract:
Lines can be freely varied in thickness, and lines with characteristics such as “stops”, “flicks”, and “sweeping strokes” can be written easily, even with a felt-tip pen, marker pen, or the like. Moreover, a pen-tip does not readily become damaged or worn. A writing implement includes a shaft, an ink supply core such as that of a felt-tip pen or a marker pen, and a core surrounding member that covers the ink supply core. The writing implement is formed capable of contacting a tip of the ink supply core and a tip of the core surrounding member against a writing surface at the same time by using a joint capable of changing a relative positional relationship between the ink supply core and the core surrounding member.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a felt-tip pen, a marker pen, or the like that is capable of writing with a variable line width. 
       BACKGROUND 
       [0002]    Ballpoint pens exist that, in order to enable writing with line widths of varying thicknesses, are formed capable of front-rear displacement of the relative positions of a holder, this being part of a ballpoint pen-tip, and an outer member that covers the outer periphery of the ballpoint pen-tip, to a holder retracted position covering as far as a portion where a tip of the outer member reaches a compression deformed swaged section at a leading end of the holder. Note that when the relative positions of the outer member and the holder are at the holder retracted position, a writing ball and the tip of the outer member are capable of contacting a writing surface at the same time. Patent Document 1 below describes an example of such technology. 
         [0003]    Patent Document 1: JPA 2013-252655 
       SUMMARY 
     Technical Problem 
       [0004]    However, the invention of Patent Document 1 relates to a ballpoint pen, and the thickness of the line that can be written is limited. The present invention provides a writing implement such as a felt-tip pen or marker pen for writing characters with thick lines that cannot be achieved using a ballpoint pen. The writing implement includes a pen tip that enables the width of a line to be freely varied, enables lines with characteristics such as “stops”, “flicks”, and “sweeping strokes” to be written easily, and is less susceptible to damage and wear than the pen tips of existing felt-tip pens, markers, and the like. 
       Solution to Problem 
       [0005]    In order to address the above issue, the present invention includes configurations such as the following. 
       First Aspect 
       [0006]    A first aspect of the present invention is a writing implement  1  including: a shaft  10 ; an ink supply core  50 , such as that of a felt-tip pen or marker pen, that is housed inside the shaft  10 , and that is capable of guiding ink by capillary force; a core surrounding member  20  that covers an outer periphery of the ink supply core  50  such that a portion of the ink supply core  50  and a portion of the core surrounding member  20  are exposed at a leading end of the shaft  10 ; and a displacement means  30  that is capable of changing a relative positional relationship between the ink supply core  50  and the core surrounding member  20  in an axial direction. The writing implement  1  is formed such that the ink supply core  50  is moved by the displacement means  30  relatively rearward with respect to the core surrounding member  20  so as to enable a tip of the ink supply core  50  and a tip of the core surrounding member  20  to contact a writing surface at the same time. 
         [0007]    The shaft  10  is an outer section structure of the writing implement  1 , has a closed rear end, and has a tapered profile at a leading end. An opening is present in a leading end face of the shaft  10 . Ink is stored inside the shaft  10 . There is no particular limitation to the manner in which this is achieved, and ink may be stored inside the shaft  10  directly, or an ink refill filled with ink may be stored inside the shaft  10 . 
         [0008]    The ink supply core  50  is formed by extrusion molding a resin material such as polyacetal. During extrusion molding, a path is formed that guides ink to the tip of the ink supply core  50  by capillary action. Moreover, the ink supply core  50  may be a fiber core, a sintered core, or the like. 
         [0009]    The core surrounding member  20  is a substantially conical shaped member that covers at least the ink supply core  50  exposed from the shaft  10 , and is preferably formed from a resin material such as polyacetal. 
         [0010]    The displacement means  30  is a means to enable the relative positional relationship between the ink supply core  50  and the core surrounding member  20  to be changed. The displacement means  30  encompasses both displacement of the ink supply core  50  in cases in which the ink supply core  50  is formed so as to be capable of moving with respect to the core surrounding member  20 , and displacement of the core surrounding member  20  in cases in which the core surrounding member  20  is formed so as to be capable of moving with respect to the ink supply core  50 . 
         [0011]    In the writing implement of the present aspect, when the relative positional relationship between the ink supply core  50  and the core surrounding member  20  is changed by the displacement means  30  such that the ink supply core  50  projects out from the tip of the core surrounding member  20 , only the tip of the ink supply core  50  contacts the writing surface, enabling a line to be drawn at the thickness capable of being written using the surface of the ink supply core  50 . 
         [0012]    However, when writing is started in a state in which the relative positional relationship between the ink supply core  50  and the core surrounding member  20  has been changed by the displacement means  30  such that the ink supply core  50  has moved rearward relative to the core surrounding member  20 , and the tip of the ink supply core  50  and the tip of the core surrounding member  20  are in contact with the writing surface at the same time, the ink held by the ink supply core  50  flows out accompanying writing. The ink that has flowed out spreads due to capillary action between the tip of the ink supply core  50  and the tip of the core surrounding member  20  that are in contact with the writing surface. As a result, a broader line can be drawn than when writing in a state in which only the tip of the ink supply core  50  is in contact with the writing surface. 
         [0013]    Moreover, when writing with the tip of the ink supply core  50  and the tip of the core surrounding member  20  in contact with the writing surface at the same time due to the displacement means  30 , writing pressure applied during writing is borne mainly by the core surrounding member  20 , enabling the writing pressure placed on the ink supply core  50  that holds the ink to be reduced. This thereby enables wear of the pen tip of the ink supply core  50  to be reduced. 
       Second Aspect 
       [0014]    A second aspect of the present invention is the first aspect, wherein the displacement means  30  is an elastic member  30  disposed at a rear of the ink supply core  50 , and the relative positional relationship between the ink supply core  50  and the core surrounding member  20  can be changed by compression of the elastic member  30 . The writing implement  1  is formed such that the ink supply core  50  is formed so as to be able to move rearward relative to the core surrounding member  20 , from an initial position that is a portion of the ink supply core  50  that is exposed from the core surrounding member  20 , by the elastic member  30  being compressed with load applied to the tip of the ink supply core  50 . 
         [0015]    The present aspect specifies the displacement means  30  of the first aspect. 
         [0016]    The displacement means  30  is capable of changing the relative positional relationship between the ink supply core  50  and the core surrounding member  20  between a position where the ink supply core  50  has been moved rearward relative to the core surrounding member  20  (referred to below as the “retracted position”), and a position where the ink supply core  50  projects out from the tip of the core surrounding member  20  (referred to below as the “projecting position”). 
         [0017]    The elastic member  30  serving as the displacement means  30  is formed from an elastic material, such as rubber or a spring. This thereby enables the elastic member  30  to return to its initial shape under the elastic action of the elastic member  30  when in a compressed shape. 
         [0018]    In the present aspect, the ink supply core  50  is formed capable of undergoing displacement with respect to the shaft  10  and the core surrounding member  20 . Note that when writing load from the direction of the tip acts on the ink supply core  50 , the ink supply core  50  moves relatively rearward with respect to the core surrounding member  20 . When the writing load acting on the ink supply core  50  is lifted, the elastic member  30  returns to its initial shape under elastic action, accompanying which the ink supply core  50  also returns to the projecting position. 
         [0019]    Due to the above configuration, the present aspect enables lines of different thicknesses to be drawn by varying the writing load. Moreover, configuring the elastic member  30  from a soft member with a low modulus of elasticity enables thick lines to be drawn irrespective of the writing load, and at any angle, by those with weaker strength, such as the elderly or small children. 
         [0020]    Moreover, if the load required to move from the projecting position to the retracted position is very small in comparison to the writing load, the ink supply core  50  can be displaced to the retracted position to enable thick lines to be drawn consistently, without writing becoming uncomfortable. Moreover, when the writing load is lightened due to separation of the writing section from the writing surface in an action to produce a “stop” or “sweeping stroke”, for example, the ink supply core  50  is displaced from the retracted position toward the projecting position in a continuous manner, thus giving a continuous and smooth transition in the width of the writing from a broad line to a thin line. 
         [0021]    Moreover, due to the shape of the elastic member  30 , a change in internal volume accompanying deformation of the elastic member  30  can be utilized, such that an ink flow path is placed in a pressurized state by the writing load to give a good ink flow rate at the start of writing. 
       Third Aspect 
       [0022]    A third aspect of the present invention is the first or the second aspect, wherein an ink supply space including a gap exhibiting capillary force is formed at an inside of the ink supply core  50 , and ink is guided by the capillary force of the ink supply space. 
         [0023]    The present aspect specifies the location at which capillary force is exhibited in the ink supply core  50  of the first or the second aspect. 
         [0024]    The ink supply space in the third aspect is formed by extrusion molding of the ink supply core  50  so that finely controlled paths are left inside the ink supply core  50 . These paths are employed to guide ink. 
       Fourth Aspect 
       [0025]    A fourth aspect of the present invention is the first or the second aspect, wherein an ink supply space including a gap exhibiting capillary force is formed at an outside of the ink supply core  50 , and ink is guided by the capillary force of the ink supply space. 
         [0026]    The present aspect specifies the location at which capillary force is exhibited in the ink supply core  50  of the first or the second aspect. 
         [0027]    The ink supply space in the fourth aspect is formed by extrusion molding of the ink supply core  50  so that finely controlled paths are left at the outside of the ink supply core  50 . These paths are employed to guide ink. 
       Advantageous Effects of Invention 
       [0028]    Due to the above configuration, the present invention enables lines of varying thickness to be drawn freely employing the displacement means, and enables actions such as “stops”, “flicks”, and “sweeping strokes” to be reproduced easily and with high quality even with a felt-tip pen, marker pen, or the like. Moreover, writing pressure when writing is borne mainly by the core surrounding member, thereby enabling damage to the ink supply core, serving as the pen-tip, to be prevented, and enabling wear to be reduced. Moreover, since there are no holes on the surface of the core surrounding member, unlike in the ink supply core, catching on a paper surface is reduced, enabling a smooth writing sensation. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0029]      FIG. 1A  is a front view, and  FIG. 1B  is a front cross-section, of a writing implement according to an exemplary embodiment of the present invention. 
           [0030]      FIG. 2  is an enlarged cross-section of a front side of a writing implement according to an exemplary embodiment of the present invention, when at a projecting position. 
           [0031]      FIG. 3A  is a perspective view,  FIG. 3B  is a front view, and  FIG. 3C  is a vertical cross-section, of a joint of a writing implement according to an exemplary embodiment of the present invention. 
           [0032]      FIG. 4  is an enlarged cross-section of a front side of a writing implement according to an exemplary embodiment of the present invention, when in a retracted position. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    Explanation follows with reference to the drawings regarding an example of a felt-tip pen or a marker pen, serving as a writing implement  1  according to an exemplary embodiment of the present invention, in which a writing section is provided at a leading end of a shaft  10 . Note that in the present invention, the “front” of the writing implement  1  and its configuration components refers to the direction in which the writing section is provided, and the “rear” refers to the opposite direction thereto. 
       Overall Configuration 
       [0034]    As illustrated in  FIG. 1A , an external profile of the writing implement  1  according to the exemplary embodiment of the present invention includes the shaft  10  that is provided with a tip shaft  11  and a rear shaft  12 , and an outer member  20 , serving as a core surrounding member  20 , fixed to the front side of the tip shaft  11  serving as the writing section. As illustrated in  FIG. 1B , an ink supply core  50 , serving as the writing section, is housed inside the shaft  10  spanning from the front side of the tip shaft  11  to a leading end of the outer member  20 . 
       Structure of the Shaft  10   
       [0035]    As illustrated in  FIG. 1B , the structure of the writing implement  1  according to the exemplary embodiment of the present invention is configured by a cylindrical shaped ink tank  13  having a closed rear end, the tip shaft  11 , that has a cylindrical shape with a tapered profile at a leading end, and with a leading end of the ink tank  13  fitted into the inner periphery of the rear end of the tip shaft  11 , and the cylindrical shaped rear shaft  12  having a closed rear end and having the rear end of the tip shaft  11  fitted into the inner periphery of the leading end of the rear shaft  12 . 
         [0036]    As illustrated in  FIG. 1B , the tip shaft  11  has a substantially cylindrical shape, and has a tapered profile at its leading end. The outer periphery of the tip shaft  11  is provided with a tip shaft flange  15  at a position approximately ⅓ of the way from the rear end of the tip shaft  11 . The tip shaft flange  15  has an outer diameter that is substantially the same diameter as the outer diameter of the rear shaft  12 , and the leading end of the rear shaft  12  abuts the tip shaft flange  15 . The tip shaft  11  includes, on each side of a boundary of the tip shaft flange  15 , a substantially cylindrical tube shaped tip shaft rear portion  14  toward the rear side, and a tip shaft front portion  16  with a tapered profile toward the front side. 
         [0037]    As illustrated in  FIG. 2 , a leading end portion of the tip shaft front portion  16  is provided with a tip shaft front reduced diameter hole  16   a  having a reduced diameter, into which a leading end of a joint  30  is inserted, and an outer member insertion hole  16   b  is contiguously provided to the front of the tip shaft front reduced diameter hole  16   a  and has the outer member  20  inserted therein. A groove is provided on the outer periphery of the tip shaft front portion  16  in the vicinity of the leading end thereof, so as to enable mounting of another member, and an anti-slip grip member  17  is mounted in the groove. 
       Internal Structure of the Tip Shaft  11   
       [0038]    As illustrated in  FIG. 1B , a collector  40  made from an ABS resin is press-fitted inside the tip shaft front portion  16 . In the collector  40 , plural plate shaped members are disposed running parallel to the axial direction. Ink, not illustrated in the drawings, can be held between the plate shaped members. Moreover, a collector core  41 , formed from a bundle of fibers, runs through the axial center of the collector  40 . The joint  30  is mounted at the front side of the tip shaft  11 , namely in front of the collector  40 . 
       Overall Structure of the Joint  30   
       [0039]    As illustrated in  FIG. 3A , the joint  30  is configured from a substantially cylindrical shaped center member  31 , a substantially cylindrical shaped surrounding member  32  formed from approximately ¼ from the rear end of the center member  31  to approximately ⅓ from the rear end of the center member  31 , such that gap sections  34  of the thickness of the leading end of the collector  40  are present at the outer periphery of the rear of the center member  31 , and an interposing member  33  formed so as to cover the center member  31  from a leading end of the surrounding member  32  to a position approximately ⅓ back from a leading end of the center member  31 . 
       Center Member  31   
       [0040]    As illustrated in  FIG. 2 , the collector core  41  is inserted into the center member  31  from the rear, and the ink supply core  50  is inserted into the center member  31  from the front. 
         [0041]    As illustrated in  FIG. 3C , at the inner periphery of the center member  31 , a back insertion hole  31   a  having substantially the same diameter as the collector core  41  is provided at the rear end of the center member  31 , and a center insertion hole  31   b  and a tip insertion hole  31   c  having substantially the same diameter as the ink supply core  50  are provided from the center toward the leading end of the center member  31 . 
         [0042]    Moreover, a ring shaped center member flange  31   e  is formed on the outer periphery of the center member  31 , in the vicinity of the rear end of the center insertion hole  31   b  of the center member  31 , and positioned further toward the front than the leading end of the surrounding member  32 . The outer periphery of the center member  31  is configured from: a rear circular columnar rear section  31   d  provided at a position from a rear end of the center member  31  up to the center member flange  31   e ; a rear circular columnar front section  31   f  positioned from the center member flange  31   e  up to the vicinity of a leading end of the center insertion hole  31   b ; a central circular columnar section  31   g  positioned from a leading end of the rear circular columnar front section  31   f  up to slightly further to the front than the leading end of the center insertion hole  31   b ; and a front circular columnar section  31   h  positioned from a leading end of the central circular columnar section  31   g  up to the leading end of the center member  31 . 
         [0043]    Note that the outer diameters of the rear circular columnar rear section  31   d  and the rear circular columnar front section  31   f  are substantially the same diameter as the inner diameter of a leading end portion of the collector  40 , and the outer diameter of the central circular columnar section  31   g  is substantially the same diameter as the diameter of the tip shaft front reduced diameter hole  16   a . Moreover, the outer diameter of the front circular columnar section  31   h  is substantially the same as the diameter of a rear insertion hole  24  provided in the rear of the outer member  20 , illustrated in  FIG. 2 . 
       Surrounding Member  32   
       [0044]    The inner diameter of the surrounding member  32  illustrated in  FIG. 3  is substantially the same diameter as the outer diameter of the leading end portion of the collector  40 . Moreover, as illustrated in  FIG. 3C , a surrounding member wide diameter portion  32   a  is provided with slightly widened diameter at the inner periphery of the surrounding member  32  at a position at a rear end of the surrounding member  32 . A surrounding member inner projection  32   b  formed in a ring shape is provided at the inner periphery of the surrounding member  32  at a position approximately halfway from the rear end of the surrounding member  32 . The surrounding member inner projection  32   b  is provided to clamp the leading end portion of the collector  40 , using the surrounding member  32  and the center member  31 . 
         [0045]    Moreover, the outer periphery of the surrounding member  32  is configured from a surrounding member rear outer peripheral portion  32   c  at a position between the rear end of the surrounding member  32  and the surrounding member inner projection  32   b , a surrounding member central outer peripheral portion  32   d  contiguous to the surrounding member rear outer peripheral portion  32   c , and a surrounding member front outer peripheral portion  32   e  contiguous to the surrounding member central outer peripheral portion  32   d  at a position up to a leading end of the surrounding member  32 . 
         [0046]    A ring shaped surrounding member outer projection  32   f  is provided at a position approximately halfway back from a leading end of the surrounding member front outer peripheral portion  32   e . A cutout, not illustrated in the drawings, is provided at the surrounding member outer projection  32   f  at at least one location in the circumferential direction. The outer diameter of the cutout is the same as the outer diameter of the surrounding member front outer peripheral portion  32   e.    
       Interposing Member  33   
       [0047]    As illustrated in  FIG. 3C , the interposing member  33  is configured from an interposing member rear circular columnar section  33   a  with a substantially cylindrical tube shape covering the surrounding member  32  and having substantially the same outer diameter as the diameter of the surrounding member outer projection  32   f , a coupling section  33   b  that is contiguously provided to the interposing member rear circular columnar section  33   a , that covers as far as the center member flange  31   e , and that has a substantially conical shape, and an interposing member front conical section  33   c  that is contiguously provided to the coupling section  33   b , and that is formed in a gently-sloping conical shape covering as far as the vicinity of a leading end of the central circular columnar section  31   g.    
         [0048]    The interposing member rear circular columnar section  33   a  is interposed between a rear end of the surrounding member front outer peripheral portion  32   e  and the cutout of the surrounding member  32 , and covers as far as the leading end of the surrounding member front outer peripheral portion  32   e . As a result, the interposing member rear circular columnar section  33   a  engages with the surrounding member outer projection  32   f.    
         [0049]    Note that the inner periphery of the interposing member  33  is formed so as to follow the outer peripheries of the center member  31  and the surrounding member  32 , and an inner diameter of the rear end side of the coupling section  33   b  is the same as the inner diameter of the surrounding member  32 . Moreover, the inner diameter of the front end side of the coupling section  33   b  has a tapered shape gradually decreasing so as to transition from the inner diameter of the interposing member  33  to the outer diameter of the center member flange  31   e.    
       Two Color Molding 
       [0050]    The joint  30  is a component molded by two-color molding. The center member  31  and the surrounding member  32  are molded by primary molding, and the interposing member  33  is integrally molded onto the center member  31  and the surrounding member  32  by secondary molding. The interposing member  33  is provided with flexibility due to being formed from an elastic resin material at the coupling section  33   b.    
         [0051]    A thermoplastic elastomer is preferably employed as the elastic resin material in order to perform a molding process using a mold at high temperature. The material of the center member  31  and the surrounding member  32  configuring a primary molded body is preferably a hard resin, such as a PBT resin. 
       Outer Member  20   
       [0052]    As illustrated in  FIG. 2 , the outer member  20  is configured from a cylindrical tube shaped outer member fixing portion  21 , and an outer member taper portion  22  that is contiguously provided to the outer member fixing portion  21  and has a substantially circular conical shape. A beveled outer member tip portion  23  is provided at the leading end of the outer member taper portion  22 . 
         [0053]    A hole is formed through from a rear end toward the leading end of the outer member  20 . Specifically, the rear insertion hole  24  is provided along the inner periphery of the outer member fixing portion  21 , and a front insertion hole  25  of smaller diameter than the rear insertion hole  24  is provided along the inner periphery of the outer member taper portion  22  in the vicinity of its leading end. 
         [0054]    The outer member fixing portion  21  is fixed to the tip shaft  11  by fitting into the outer member insertion hole  16   b . The outer member  20  covers the ink supply core  50 . Simultaneously, the front circular columnar section  31   h  (see  FIG. 3B  and  FIG. 3C ) of the joint  30  is inserted into the rear insertion hole  24 , and the ink supply core  50  projecting out from the joint  30  is inserted into the front insertion hole  25 . 
       Ink Supply Core  50   
       [0055]    The ink supply core  50  illustrated in  FIG. 2  is molded by extrusion molding a resin material such as polyacetal. During extrusion molding, a path is formed that guides ink to the tip of the ink supply core  50  by capillary action. 
         [0056]    Note that during extrusion molding, the ink guiding path mentioned above may be configured by forming gaps exhibiting capillary force inside the ink supply core  50 , or by forming gaps exhibiting capillary force at the outside of the ink supply core  50 . Moreover, the ink supply core  50  may be a fiber core, a sintered core, or the like. 
       Characteristics of the Writing Implement  1   
       [0057]    In the writing implement  1  according to the exemplary embodiment of the present invention, the joint  30  is configured from three members. The joint  30  has a characteristic structure in which, even though the surrounding member  32  and the center member  31  are the same primary molded body, they are not continuous to each other in the primary molded body. The interposing member  33  accordingly deforms in the vicinity of the coupling section  33   b , such that the joint  30  flexes readily. 
         [0058]    Accordingly, as illustrated in  FIG. 4 , a relative positional relationship between the ink supply core  50  and the outer member  20  is displaced due to the joint  30  flexing under writing pressure, thereby enabling the ink supply core  50  to move toward a retracted position. 
         [0059]    On the other hand, as illustrated in  FIG. 2 , when the writing load is reduced and the writing pressure applied to the ink supply core  50  becomes lighter, the joint  30  returns from the flexed shape to its initial shape under elastic action, accompanying which the ink supply core  50  also returns to a projecting position. 
         [0060]    Note that when the ink supply core  50  is moved to the retracted position under writing pressure, and writing is started with the tip of the ink supply core  50  and the tip of the outer member  20  both in contact with the writing surface at the same time, the ink held by the ink supply core  50  flows out accompanying the writing. Then, the ink that has flowed out spreads due to capillary action between the tip of the ink supply core  50  and the tip of the outer member  20  that are in contact with the writing surface. As a result, a broader line can be drawn than when writing in a state in which only the tip of the ink supply core  50  is in contact with the writing surface. 
         [0061]    Moreover, when the ink supply core  50  is moved to the retracted position under writing pressure, and writing is performed with the tip of the ink supply core  50  and the tip of the outer member  20  in contact with the writing surface at the same time, the writing pressure applied when writing is borne mainly by the outer member  20 , enabling the writing pressure placed on the ink supply core  50  that holds the ink to be reduced. This thereby enables wear of the pen tip of the ink supply core  50  to be reduced. Moreover, the ink supply core  50  is covered by the outer member  20 , such that even if the pen tip is knocked or receives a shock from being dropped, the ink supply core  50  does not suffer damage that renders it incapable of writing. Moreover, unlike the ink supply core, the core surrounding member does not have holes in its surface, thereby reducing catching on the paper surface to give a smooth writing sensation. 
         [0062]    Moreover, due to utilizing the elastic action of the joint  30 , the ink supply core  50  moves forward from the retracted position toward the projecting position in a continuous action when the writing load is lightened by removing the writing section from the writing surface with an action that produces a “stop” or a “sweeping stroke”. This thereby enables a continuous and smooth transition in the width of the writing, from a broad line to a thin line.