Patent Publication Number: US-2003231921-A1

Title: Writing implement

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to a writing implement, and more particularly to a writing implement capable of preventing discharge of excessive ink which is caused by an increase of pressure in the writing implement or an outer impact.  
       [0003] 2. Description of the Related Art  
       [0004] It is well known to provide a pen having free ink that a user can selectively apply to a substrate such as paper, metal, or plastic. Such known pens typically include a reservoir for storing the ink and a channel for directing the ink from the reservoir to a marking tip. The ink of such known pens typically has a vapor pressure such that the ink, and any air in the reservoir, expands and contracts in response to changes in ambient temperature and pressure. Such expansion and contraction can cause the ink to leak from the writing tip of the pen, under certain conditions.  
       [0005] Other such known pens include a buffer for storing ink that would otherwise leak through the tip in response to changes in ambient temperature and pressure. The excess ink is typically stored in the front of the buffer, near the tip of the pen, due to gravity, when the pen is in the tip-down position. However, such known pens have several disadvantages: the ink capacity of the buffer is limited such that when the buffer is full the excess ink leaks from the pen, and the ink is often permanently stored in the buffer resulting in decreased buffer capacity and wasted ink. Another of such known pens provides for the clearing of ink from the buffer when the pressure inside the pen increases by venting air into the pen through an external vent. Such known pens, however, clear only a small portion of the buffer. Still other pens have achieved hydrostatic stability, but only with design restrictions that require stringent manufacturing tolerances and result in reduced ink flow rates.  
       [0006] U.S. patent application Ser. No. 10/106,552 (filed by Witz et al. on Mar. 26, 2002, and already published on Nov. 14, 2002) discloses a hydrostatically stable writing implement in which ink is hardly leaked in response to changes in temperature and pressure and which has a design freedom and improved current rate of the ink.  
       [0007]FIG. 1 is a longitudinally sectional view of the writing implement  10  according to the above-mentioned Witz&#39;s patent application. As shown in FIG. 1, the writing implement  10  according to the above-mentioned patent application includes a housing  12 , a reservoir  14  for storing ink within the housing  12 , a feed tube  16  which is communicated with the reservoir  14 , for supplying the ink, a tip  18  which is disposed in the feed tube  16 , for conveying the ink to a substrate at an end thereof, a porous buffer  20  which is disposed to be adjacent to the feed tube  16  in the housing  12 , for storing the ink during a period of decreasing pressure differential between the reservoir  14  and atmosphere, and bubble separation area  22  in the form of a hole or passage in the feed tube  16  or between the feed tube  16  and the tip  18 .  
       [0008] The ink stored in the reservoir  14  of the housing  12  moves through the feed tube  16  to the tip  18 . When the excessive ink moves to the tip  18 , the porous buffer  20  absorbs and stores a part of the ink by capillarity thereof.  
       [0009] When the changes in temperature and pressure of atmosphere cause the air and the ink in the reservoir  14  to expand and move through the feed tube  16  to the tip  18 , meanwhile, the buffer  20  absorbs and stores the part of the ink.  
       [0010] In the writing implement  10  according to the Witz&#39;s patent application, however, since the tip  18  has the capillarity different from that of the buffer  20 , the ink stored in the buffer  20  moves to the tip  18  by the capillarity thereof when the buffer  20  stores a large quantity of the ink. Thereby, a great amount of the ink which is more than a necessary quantity, leaks from the tip  18 .  
       SUMMARY OF THE INVENTION  
       [0011] The present invention has been developed to solve the above-mentioned problem. It is an object of the present invention to provide a writing implement capable of preventing the ink from being excessively dispensed in response to changes in temperature and pressure in a reservoir, or an outer impact.  
       [0012] In order to achieve the object of the present invention, according to an embodiment of the present invention, there is provided a writing implement which comprises: a housing; a reservoir for storing ink within the housing; an ink supplying pipe which is communicated with the reservoir, for guiding flow of the ink; an ink feeder which is disposed in the ink supplying pipe, for absorbing and storing the ink which flows through the ink supplying pipe from the reservoir so as to control a current rate of the ink; a buffer which is disposed in the housing with enclosing an outer peripheral surface of the ink supplying pipe, for temporally storing the ink during reducing pressure differential between the reservoir and atmosphere; and a tip which is disposed in the housing, for conveying the ink from the ink feeder to a substrate, the tip having one end which comes in contact with one ends pf the ink supplying pipe and the ink feeder and the other end which extends out of the housing.  
       [0013] According to the embodiment of the present invention, a plurality of ribs are formed at a distance from one another on an inner peripheral surface of the housing to extend at a predetermined length from an end of the housing, along which air moves into the housing when the ink is conveyed from the tip to the substrate.  
       [0014] The ink supplying pipe includes a circular head portion which has a diameter corresponding to an inner diameter of the housing and in which a slit is radially formed at an area spaced at a predetermined distance apart from a center thereof.  
       [0015] A plurality of slots are formed at a predetermined distance from one another along the outer peripheral surface of the ink supplying pipe, through which excessive ink supplied to the ink feeder moves to the buffer.  
       [0016] The buffer has one end which comes in contact with the head portion of the ink supplying pipe and the other end which encloses one end of the tip, of which the outer peripheral surface comes in contact with the inner peripheral surface of the housing.  
       [0017] In the writing implement according to the embodiment of the present invention which is constructed as described above, even though the ink excessively expanses and moves to the tip in response to change in temperature or pressure in the reservoir, the ink feeder and buffer temporarily stores a part of the ink, resulting in regularly supplying the ink to the tip. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0018] The above objects and advantages of the present invention will become more apparent by describing in detail the preferred embodiments thereof with reference to the attached drawings, in which:  
     [0019]FIG. 1 is a longitudinally sectional view of a writing implement according to the conventional art;  
     [0020]FIG. 2 is a longitudinally sectional view of a writing implement according to a first embodiment of the present invention;  
     [0021]FIG. 3 is a longitudinally sectional view of a writing implement according to a second embodiment of the present invention;  
     [0022]FIG. 4 is a longitudinally sectional view of a writing implement according to a third embodiment of the present invention;  
     [0023]FIG. 5 is a longitudinally sectional view of a writing implement according to a fourth embodiment of the present invention;  
     [0024]FIG. 6 is a longitudinally sectional view of a writing implement according to a fifth embodiment of the present invention;  
     [0025]FIG. 7 is a partially enlarged sectional view of the writing implement according to the fifth embodiment of the present invention;  
     [0026]FIG. 8 is a cross-sectional view of the writing implement according to the fifth embodiment of the present invention, taken along a line D-D′;  
     [0027]FIG. 9 is a cross-sectional view of the writing implement according to the first embodiment of the present invention, taken along a line A-A′ in FIG. 2;  
     [0028]FIG. 10 is a cross-sectional view of the writing implement according to the first embodiment of the present invention, taken along a line A-A′ in FIG. 2, in which the other ink supplying pipe is applied to the writing implement;  
     [0029]FIG. 11 is a cross-sectional view of the writing implement according to the first embodiment of the present invention, taken along a line B-B′ in FIG. 2;  
     [0030]FIG. 12 is a cross-sectional view of the writing implement according to the first embodiment of the present invention, taken along a line C-C′ in FIG. 2;  
     [0031]FIG. 13 is an exploded view of an ink supplying pipe applicable to the writing implements according to the first, second, third, fourth and fifth embodiments of the present invention, in which a plurality of slots are formed along an outer peripheral surface of the ink supplying pipe at a predetermined portion of the ink supplying pipe;  
     [0032]FIG. 14 is an exploded view of another ink supplying pipe applicable to the writing implements according to the first, second, third, fourth and fifth embodiments of the present invention, in which a plurality of thru-holes are formed along an outer peripheral surface of the ink supplying pipe at a predetermined portion of the ink supplying pipe;  
     [0033]FIG. 15 is an exploded view of still another ink supplying pipe applicable to the writing implements according to the first, second, third, fourth and fifth embodiments of the present invention, in which a mesh member is mounted in the ink supplying pipe;  
     [0034]FIG. 16 is a sectional view of a first modification of an ink supplying pipe applicable to the writing implements according to the first, second, third, fourth and fifth embodiments of the present invention;  
     [0035]FIG. 17 is a sectional view of a second modification of the other ink supplying pipe applicable to the writing implements according to the first, second, third, fourth and fifth embodiments of the present invention;  
     [0036]FIG. 18 is a sectional view of an intercepting member applicable to the writing implements according to the first, second, third and fourth embodiments of the present invention;  
     [0037]FIG. 19 is a sectional view of a first modification of a tip applicable to the writing implements according to the first, second, third, fourth and fifth embodiments of the present invention; and  
     [0038]FIG. 20 is a sectional view of a second modification of a tip applicable to the writing implements according to the first, second, third, fourth and fifth embodiments of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0039] Hereinafter, a writing implement according to the embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The like reference numeral indicates the like element.  
     [0040]FIG. 2 is a longitudinally sectional view of a writing implement  100  according to the first embodiment of the present invention. As shown in FIG. 2, the writing implement  100  according to the first embodiment of the present invention comprises a housing  110 , a reservoir  120  for storing ink within the housing  110 , an ink supplying pipe  130  which is communicated with the reservoir  120 , for guiding flow of the ink, an ink feeder  140  which is disposed in the ink supplying pipe  130 , for absorbing and storing the ink which flows through the ink supplying pipe  130  from the reservoir  120  so as to control a current rate of the ink, a buffer  150  which is disposed in the housing  110  with enclosing an outer peripheral surface of the ink supplying pipe  130 , for temporally storing the ink during decreasing pressure differential between the reservoir  120  and atmosphere, and a tip  160  which is disposed in the housing  110 , for conveying the ink from the ink feeder  140  to a substrate (not shown), the tip  160  having one end which comes in contact with one ends pf the ink supplying pipe  130  and the ink feeder  140  and the other end which extends out of the housing  110 .  
     [0041] The housing  110  has one end air-tightly enclosed and the other end having a truncated conical shape. The tip  160  is inserted at the one end into the housing  110 . A plurality of ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  are formed at a predetermined distance from one another on an inner peripheral surface of the housing  110  to extend at a predetermined length from the other end of the housing  110 , along which air moves into the housing  110  when the ink is conveyed from the tip  160  to the substrate (not shown).  
     [0042] As shown in FIGS. 1 and 9, the ink supplying pipe  130  has a circular head portion  132  of which a diameter is in correspondence to an inner diameter of the housing  110  and in which a slot  134  is radially formed from a position spaced at a predetermined distance from a center portion thereof. The head portion  132  has an outer peripheral surface to be in close contact with the inner peripheral surface of the housing  110 .  
     [0043] A step portion  136  is formed in an inner peripheral surface of the ink supplying pipe  130 . A thru-hole extending from the step portion  136  to one end of the ink supplying pipe  130  has a smaller diameter than that of a thru-hole extending from the head portion  132  to the step portion  136 .  
     [0044] At an area adjacent to the end of the ink supplying pipe  130 , furthermore, a plurality of slots  138  are formed at a predetermined distance from one another along a peripheral surface of the ink supplying pipe  130 , through which the excessive ink supplied to the ink feeder  140  moves to the buffer  150 .  
     [0045] The area of the ink supplying pipe  130  in which the slots  138  are formed has a thickness of about 0.1 mm to 0.5 mm according to properties of the ink, for examples surface tension, viscosity, specific gravity, and the like. When the ink supplying pipe  130  has the thickness less than 0.1 mm, the ink feeder  140  is placed adjacent to the buffer  150  in the presence of the slots  138  between the ink feeder  140  and the buffer  150 , so that the ink excessively moves by the capillarity of the buffer  150  from the ink feeder  140  to the buffer  150 . When the ink supplying pipe  130  has the thickness more than 0.5 mm, on the other hand, the ink feeder  140  is spaced apart from the buffer  150  in the presence of the slots  138  between the ink feeder  140  and the buffer  150 , so that the capillarity of the buffer  150  cannot make an effect on the ink feeder  140  even if the excessive ink is supplied to the ink feeder  140 . Thus, the excessive ink supplied to the ink feeder  140  does move not to the buffer  150  but to the tip  160 .  
     [0046] The ink feeder  140  is inserted in the ink supplying pipe  130  in which one end of the ink feeder  140  extends through the step portion  136  of the ink supplying pipe  130  while the other end of the ink feeder  140  is placed in the same plane along with the one end of the ink supplying pipe  130 . Accordingly, the one end of the ink feeder  140  comes in contact with the tip  160  along with the one end of the ink supplying pipe  130 . The ink feeder  140  temporarily stores the ink introduced from the reservoir  120  into the ink supplying pipe  130 , which regularly supplies the stored ink to the tip  160 .  
     [0047] When the increase of the temperature and the pressure in the reservoir causes the excessive ink to move to the ink feeder  140 , the ink leaks and moves through the slots  138  formed in the ink supplying pipe  130  from the ink feeder  140  to the buffer  150 . The ink moving to the buffer  150  is absorbed by the capillarity of the buffer  150  to be temporarily stored in the buffer  150 .  
     [0048] The buffer  150  is made of synthetic material, which is a porous and cylindrical tube. The buffer  150  has one end coming in contact with the head portion  132  of the ink supplying pipe  130 , and the other end enclosing the one end of the tip  160 . The outer peripheral surface of the buffer  150  comes in close contact with the inner peripheral surface of the housing  110 . Meanwhile, the certain portions of the outer peripheral surface of the buffer  150  contacting with the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  are inwardly pushed by means of the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h , as shown in FIGS. 11 and 12. Furthermore, the inner peripheral surface of the buffer  150  comes in tight contact with the outer peripheral surface of the ink supplying pipe  130 .  
     [0049] The buffer  150  contains the air which is introduced into the housing  110  along the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  while the ink moves through the tip  160  to the substrate. In addition, the buffer  150  stores the ink which is introduced through the slit  134 , which is formed in the head portion  132  of the ink supplying pipe  130 , from the reservoir  120  into the buffer  150 . The air stored in the buffer  150  moves to the reservoir  120  through the head portion  132  of the ink supplying pipe  130  until the pressure in the housing  110  makes in a state of equilibrium to the atmosphere pressure.  
     [0050] Further, the buffer  150  absorbs and temporarily stores the ink stored in the ink feeder  140  and the tip  160  by the capillarity thereof when the excessive ink is supplied to the ink feeder  140  and the tip  160 .  
     [0051] Hereinafter, an operation of the writing implement  100  according to the first embodiment of the present invention will be described in detail.  
     [0052] In the writing implement  100  according to the first embodiment of the present invention which is constructed as described above, the ink is stored in the reservoir  120  of the housing  110 . When a user uses the writing implement  100 , or when the ink expands in response to the changes in the temperature and the pressure, the ink moves to the ink feeder  140  and the buffer  150  through the ink supplying pipe  130  and the slit  134  formed in the head portion  132  of the ink supplying pipe  130 .  
     [0053] Most of the ink flows into the ink supplying pipe  130 , which is stored in the ink feeder  140 . A part of the ink is introduced through the slit  134  into the buffer  150 . The ink stored in the ink feeder  140  moves to the tip  160  by gravity and the capillarity of the ink feeder  140 . The ink moving to the tip  160  in the ink feeder  140  is introduced into the buffer  150  through the slit  134  of the ink supplying pipe  130  until the pressure in the housing  110  equilibriums the atmosphere pressure.  
     [0054] The ink introduced into the buffer  150  is temporarily stored in the buffer  150 . The ink moves to the ink feeder  140  or the tip  160  as the ink in the tip  160  is spent.  
     [0055] On the other hand, while the ink moves from the reservoir  120  to the ink feeder  140  and the buffer  150 , the air flows from the other end of the housing  110  into the housing  110  along the surfaces of the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  formed on the inner peripheral surface of the housing  110 . Thus, the pressure in a space between the buffer  150  and the other end of the housing  110  is equal to the atmosphere pressure.  
     [0056] The air introduced into the housing  110  is partially absorbed by the buffer  150  as moving to the reservoir  120  along the surfaces of the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  which come in contact with the outer peripheral surface of the buffer  150 .  
     [0057] The air absorbed in the ink feeder stays in a form of bubble, which moves to the reservoir  120  through the slit  134  formed in the head portion  132  of the ink supplying pipe  130  when the ink is introduced from the reservoir  120  and the ink feeder  140 . When the ink moves from the reservoir  120  to the buffer  150  and the ink feeder  140 , accordingly, a drop of the pressure in the reservoir  120  can be compensated.  
     [0058]FIG. 3 is a longitudinally sectional view of the writing implement  200  according to the second embodiment of the present invention. As shown in FIG. 3, the writing implement  200  according to the second embodiment of the present invention has the same structure as that of the writing implement  100  according to the first embodiment of the present invention, except for a buffer  250 . Therefore, the description relating to the same elements will be omitted.  
     [0059] The buffer  250  applied to the writing implement  200  according to the second embodiment of the present invention has a shorter length that the buffer  150  applied to the writing implement  100  according to the first embodiment of the present invention, of which an inner diameter at one end is larger than that at one end of the buffer  150 .  
     [0060] The buffer  250  has one end which is spaced at a predetermined distance G 1  from the head portion  132  of the ink supplying pipe  130 , and the other end which is spaced at a predetermined distance G 2  from the outer peripheral surface of the tip  160  with enclosing the one end of the tip  160 . Also, the buffer  250  has an outer peripheral surface coming in contact with the housing  110 . Thus, a gap G 2  is defined between the inner peripheral surface of the other end of the buffer  250  and the outer peripheral surface of the one end of the tip  160 .  
     [0061] In the writing implement  200  according to the second embodiment of the present invention which is constructed as described above, the ink is stored in the reservoir  120  of the housing  110 . When a user uses the writing implement  200 , or when the ink expands in response to the changes in the temperature and the pressure, the ink moves to the ink feeder  140  and the buffer  250  through the ink supplying pipe  130 , the slit  134  formed in the head portion  132  of the ink supplying pipe  130 , and the gap G 1 .  
     [0062] Most of the ink flows into the ink supplying pipe  130 , which is stored in the ink feeder  140 . A part of the ink is introduced through the slit  134  and the gap G 1  into the buffer  150 . The ink stored in the ink feeder  140  moves to the tip  160  by gravity and the capillarity of the ink feeder  140 . The ink moving to the tip  160  in the ink feeder  140  is introduced into the buffer  250  through the slit  134  of the ink supplying pipe  130  until the pressure in the housing  110  equilibriums the atmosphere pressure.  
     [0063] The ink introduced into the buffer  250  is temporarily stored in the buffer  250 . The ink moves to the ink feeder  140  or the tip  160  as the ink in the tip  160  is spent.  
     [0064] On the other hand, while the ink moves from the reservoir  120  to the ink feeder  140  and the buffer  250 , the air flows from the other end of the housing  110  into the housing  110  along the surfaces of the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  formed on the inner peripheral surface of the housing  110 . Thus, the pressure in a space between the buffer  250  and the other end of the housing  110  is equal to the atmosphere pressure.  
     [0065] The air introduced into the housing  110  is partially absorbed by the buffer  250  as moving to the reservoir  120  along the surfaces of the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  which come in contact with the outer peripheral surface of the buffer  250 .  
     [0066] The air absorbed in the ink feeder stays in a form of bubble, which moves to the reservoir  120  through the slit  134  formed in the head portion  132  of the ink supplying pipe  130  when the ink is introduced from the reservoir  120  and the ink feeder  140 . When the ink moves from the reservoir  120  to the buffer  250  and the ink feeder  140 , accordingly, a drop of the pressure in the reservoir  120  can be compensated.  
     [0067] Furthermore, the gap G 1  defined between the one end of the tip  160  and the buffer  250  functions to prevent the ink which moves the ink feeder  140  to the tip  160 , from flowing back.  
     [0068]FIG. 4 is a longitudinally sectional view of a writing implement  300  according to the third embodiment of the present invention. As shown in FIG. 4, the writing implement  300  according to the third embodiment of the present invention has the same structure as that of the writing implement  100  according to the first embodiment of the present invention, except for a buffer  350 . Thus, the description relating to the same elements will be omitted.  
     [0069] The buffer  350  applied to the writing implement  300  according to the third embodiment of the present invention includes a first buffer  352 , a second buffer  354  and a third buffer  356 . The first and second buffers  352  and  354  are disposed in the housing  110  to enclose the ink supplying pipe  130  while the third buffer  356  is placed in the housing  110  to enclose the one end of the tip  160 .  
     [0070] The first buffer  352  has a surface which comes in contact with the head portion  132  of the ink supplying pipe  130 , and the other surface which is opposite at a desired distance G 1  to a surface of the second buffer  354 .  
     [0071] The second buffer  354  of which the surface faces to the other surface of the first buffer  352  has the other surface opposite to one surface of the third buffer  356  at a desired distance G 2 . Furthermore, the other surface of the second buffer  354  faces to a part of the one end of the ink supplying pipe  130 .  
     [0072] Meanwhile, one ends of the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  which are formed on the inner peripheral surface of the housing  110 , are positioned in the gap G 1  defined between the first buffer  352  and the second buffer  354 . The air moves along the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  from atmosphere into the housing  110 , which is received in the gap G 1  between the first buffer  352  and the second buffer  354 . A part of the air in the gap G 1  is introduced and stored in the first buffer  352  and the remainder of the air stay in the gap G 1 . The air introduced in the first buffer  352  moves to the reservoir  120  through the slit  134  formed in the head portion  132  of the ink supplying pipe  130  so as to compensate a drop of the pressure in the reservoir  120  which is caused as the ink moves from the reservoir  120  to the ink supplying pipe  130  and the first buffer  352 .  
     [0073] In the writing implement  300  according to the third embodiment of the present invention which is constructed as described above, the ink is stored in the reservoir  120  of the housing  110 . When a user uses the writing implement  300  or when the ink expands in response to the changes in temperature and pressure in the reservoir  120 , the ink moves to the ink feeder  140  and the first buffer  352  through the ink supplying pipe  130  and the slit  134  formed in the head portion  132  of the ink supplying pipe  130 .  
     [0074] Most of the ink is introduced into the ink supplying pipe  130 , which is stored in the ink feeder  140 . The remainder of the ink is introduced through the slit  134  into the first buffer  352 . The gap G 1  defined between the first buffer  352  and the second buffer  354  restrains the ink introduced into the first buffer  352  from moving to the second buffer  354 . The ink stored in the ink feeder  140  moves to the tip  160  by means of gravity and the capillarity of the ink feeder  140 . The ink moving to the tip  160  in the ink feeder  140  is introduced into the second buffer  354  through the slot  138  of the ink supplying pipe until the pressure in the housing  110  makes a state of equilibrium to the atmosphere.  
     [0075] The ink introduced into the second buffer  354  is temporarily stored in the second buffer  354 . The ink in second buffer  354  moves to the ink feeder  140  as the ink in the tip  160  is spent.  
     [0076] When the excessive ink is introduced from the ink feeder  140  into the tip  160 , a part of the ink in the tip  160  moves to the third buffer  356  by the capillarity of the third buffer  356  to be stored in the third buffer  356 . When the ink in the tip  160  is spent, then, the ink is introduced from the third buffer  356  and the ink feeder  140  to the tip  160 .  
     [0077] While the ink moves from the reservoir  120  to the ink feeder  140  and the first buffer  352 , meanwhile, the air is introduced into the housing  110  from the other end of the housing  110  in which the tip  160  is inserted, along the surfaces of the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  formed on the inner peripheral surface of the housing  110 . Accordingly, the pressure in the space between the third buffer  356  and the other end of the housing  110  is maintained in a state of equilibrium to the atmosphere pressure.  
     [0078] The air introduced into the housing  110  moves to the reservoir  120  along the surfaces of the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  which come in contact with the outer peripheral surfaces of the first, second and third buffers  352 ,  354  and  356 , while being absorbed in the buffers  353 ,  354  and  356 .  
     [0079] The air absorbed in the buffers  352 ,  354  and  356  stays in a form of bubbles. When the ink is introduced from the reservoir  120  and the ink feeder  140  into the first and second buffers  352  and  354 , the air moves to the reservoir  120  through the slit  134  formed in the head portion  132  of the ink supplying pipe  130 . Accordingly, the air can compensate a drop of the pressure in the reservoir  120  which is caused as the ink moves from the reservoir  120  to the ink supplying pipe  130  and the first buffer  352 .  
     [0080]FIG. 5 is a longitudinally sectional view of a writing implement  400  according to the fourth embodiment of the present invention. As shown in FIG. 5, the writing implement  400  according to the fourth embodiment of the present invention has the same structure as that of the writing implement  300  according to the third embodiment of the present invention, except that a gap having a desired width is defined between a head portion of a ink supplying pipe and a first buffer while a gap having a predetermined width is defined between a third buffer and one end of the tip  160 . Therefore, the like reference numeral indicates the like element.  
     [0081] A buffer  450  includes a first buffer  452 , a second buffer  454  and a third buffer  456 . The first buffer  452  and the second buffer  454  is disposed in the housing  110  to enclose the ink supplying pipe  130 , while the third buffer  456  encloses the one end of the tip  160 .  
     [0082] The first buffer  452  has a surface which is opposite to the head portion  132  of the ink supplying pipe  130  at a predetermined distance G 1 , and the other surface which faces to a surface of the second buffer  454  at a desired distance G 2 .  
     [0083] The other surface of the second buffer  454  of which one surface faces to the other surface of the first buffer, is opposite to a surface of the third buffer  456  at a desired distance G 3 . Further, the one surface of the third buffer  456  faces to a part of the ink supplying pipe  130 .  
     [0084] The third buffer  456  has a larger diameter than that of the tip  160 , of which an inner peripheral surface faces to the peripheral surface of the one end of the tip  160  at a desired distance G 4 .  
     [0085] Meanwhile, the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  formed on the inner peripheral surface of the housing  110  is placed in the gap G 2  defined between the first buffer  452  and the second buffer  454 . The air moves from the atmosphere into the housing  110  along the surfaces of the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  while being received in the gap G 2  between the first buffer  452  and the second buffer  454 .  
     [0086] A part of the air received in the gap G 2  is introduced through the first buffer  452  into the gap G 1  defined between the first buffer  452  and the head portion  132  of the ink supplying pipe  130 , while the remainder of the air stays in the gap G 2 . The air introduced in the gap G 1  moves to the reservoir  120  through the slit  134  formed in the head portion  132  of the ink supplying pipe  130  to compensate a drop of the pressure in the reservoir  120  when the ink moves from the reservoir  120  to the ink supplying pipe  130  and the first buffer  452 .  
     [0087] In the writing implement  400  according to the fourth embodiment of the present invention which is constructed as described above, the ink is stored in the reservoir  120  of the housing  110 . When a user uses the writing implement  400  or when the ink expands in response to the changes in temperature and pressure in the reservoir  120 , the ink moves to the ink feeder  140  and the first buffer  452  through the ink supplying pipe  130 , the slit  134  formed in the head portion  132  of the ink supplying pipe  130 , and the gap G 1 .  
     [0088] Most of the ink is introduced into the ink supplying pipe  130 , which is stored in the ink feeder  140 . The remainder of the ink is introduced through the slit  134  and the gap G 1  into the first buffer  452 . The gap G 2  defined between the first buffer  452  and the second buffer  454  restrains the ink introduced into the first buffer  452  from moving to the second buffer  454 . The ink stored in the ink feeder  140  moves to the tip  160  by means of gravity and the capillarity of the ink feeder  140 . The ink moving to the tip  160  in the ink feeder  140  is introduced into the second buffer  454  through the slot  138  of the ink supplying pipe until the pressure in the housing  110  makes a state of equilibrium to the atmosphere.  
     [0089] The ink introduced into the second buffer  454  is temporarily stored in the second buffer  454 . The ink in second buffer  454  moves to the ink feeder  140  as the ink in the tip  160  is spent.  
     [0090] When the excessive ink is introduced from the ink feeder  140  into the tip  160 , a part of the ink in the tip  160  moves to the third buffer  456  by the capillarity of the third buffer  456  to be stored in the third buffer  456 . When the ink in the tip  160  is spent, then, the ink is introduced from the third buffer  456  and the ink feeder  140  to the tip  160 .  
     [0091] While the ink moves from the reservoir  120  to the ink feeder  140  and the first buffer  452 , meanwhile, the air is introduced into the housing  110  from the other end of the housing  110  in which the tip  160  is inserted, along the surfaces of the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  12   g  and  112   h  formed on the inner peripheral surface of the housing  110 . Accordingly, the pressure in the space between the third buffer  456  and the other end of the housing  110  is maintained in a state of equilibrium to the atmosphere pressure.  
     [0092] The air introduced into the housing  110  moves to the reservoir  120  along the surfaces of the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  which come in contact with the outer peripheral surfaces of the first, second and third buffers  452 ,  454  and  456 , while being absorbed in the buffers  453 ,  454  and  456 .  
     [0093] The air absorbed in the buffers  452 ,  454  and  456  stays in a form of bubbles. When the ink is introduced from the reservoir  120  and the ink feeder  140  into the first and second buffers  452  and  454 , the air moves to the reservoir  120  through the slit  134  formed in the head portion  132  of the ink supplying pipe  130 . Accordingly, the air can compensate a drop of the pressure in the reservoir  120  which is caused as the ink moves from the reservoir  120  to the ink supplying pipe  130  and the first buffer  452 .  
     [0094]FIG. 6 is a longitudinally sectional view of a writing implement  500  according to the fifth embodiment of the present invention. As shown in FIG. 6, the writing implement  500  according to the fifth embodiment of the present invention includes a housing  110 , a reservoir  120  for storing ink in the housing  10 , an ink supplying pipe  130  which is communicated with the reservoir  120 , for guiding flow of the ink, an ink feeder  140  which is disposed in the ink supplying pipe  130 , for absorbing and storing the ink moving through the ink supplying pipe  130  from the reservoir  120  to control current rate of the ink, a tip  160  which is disposed in the housing  110 , of which one end comes in contact with one ends of the ink supplying pipe  130  and the ink feeder  140  and of which the other end extends out of the housing  110 , for conveying the ink from the ink feeder  140  to a substrate (not shown), a buffer  550  for temporarily storing the ink during a period of decreasing pressure differential between the reservoir  120  and the atmosphere, one end surface of the ink feeder  140  being in contact with a head portion  132  of the ink supplying pipe  130  at a desired distance G 1 , and the other end surface of the ink feeder  140  being contact with a disc portion  164  of the tip  160 , and a decompression member which is partially inserted in the ink supplying pipe  130 , for controlling the flow rate of the ink moving from the reservoir  120  to the ink supplying pipe  130 .  
     [0095] As shown in FIGS. 6 and 8, the ink supplying pipe  130  includes the head portion  132  which has a diameter corresponding to that of the housing  110  and in which a slit  134  is radially and outwardly formed at a position distanced from a center portion thereof. An outer peripheral surface of the head portion  132  comes in close contact with an inner peripheral surface of the housing  110 . Meanwhile, an outer peripheral surface of one end of the ink supplying pipe  130  is cut off to be inclined at a desired angle. The one end of the ink supplying pipe  130  receives the one end of the tip  160  while pushing a surface of the disc portion  164  of the tip  160 .  
     [0096] A step portion  136  is formed at a desired position on an inner peripheral surface of the ink supplying pipe  130 . A thru-hole extending from the step portion  136  to the one end of the ink supplying pipe  130  has a smaller diameter than that of a thru-hole extending from the head portion  132  to the step portion  136 .  
     [0097] As shown in FIG. 13, furthermore, a plurality of slots  138  are formed at a desired distance from one another along the outer peripheral surface of the ink supplying pipe  130  at a portion adjacent to the one end of the ink supplying pipe  130 , through which the ink supplied to the ink feeder  140  moves to the buffer  550 .  
     [0098] The area of the ink supplying pipe  130  in which the slots  138  are formed has a thickness of about 0.1 mm to 0.5 mm according to the properties of the ink, for examples surface tension, viscosity, specific gravity, and the like. When the ink supplying pipe  130  has the thickness less than 0.1 mm, the ink feeder  140  is placed adjacent to the buffer  550  in the presence of the slots  138  between the ink feeder  140  and the buffer  550 , so that the ink excessively moves by the capillarity of the buffer  550  from the ink feeder  140  to the buffer  550 . When the ink supplying pipe  130  has the thickness more than 0.5 mm, on the other hand, the ink feeder  140  is spaced apart from the buffer  550  in the presence of the slots  138  between the ink feeder  140  and the buffer  550 , so that the capillarity of the buffer  550  cannot make an effect on the ink feeder  140  even if the excessive ink is supplied to the ink feeder  140 . Thus, the excessive ink supplied to the ink feeder  140  does move not to the buffer  550  but to the tip  160 .  
     [0099] The ink feeder  140  is inserted in the ink supplying pipe  130 , of which one end extends through the step portion  136  of the ink supplying pipe  130  while coming in contact with the one end of the tip  160 . The ink feeder  140  temporarily stores the ink introduced from the reservoir  120  into the ink supplying pipe  130 , which regularly supplies the stored ink to the tip  160 .  
     [0100] When the increase of the temperature and the pressure in the reservoir causes the excessive ink to move to the ink feeder  140 , meanwhile, the ink leaks and moves through the slots  138  formed in the ink supplying pipe  130  from the ink feeder  140  to the buffer  550 . The ink moving to the buffer  550  is absorbed by the capillarity of the buffer  550  to be temporarily stored in the buffer  550 .  
     [0101] The buffer  550  is a porous and cylindrical tube made of synthetic material. The buffer  550  has one end which faces to the head portion  132  of the ink supplying pipe  130  at a desired distance G 1  from the head portion  132 , and the other end which is opposite to the disc portion  164  of the tip  160  at a predetermined distance G 2  from the disc portion  164 . The outer peripheral surface of the buffer  550  comes in close contact with the inner peripheral surface of the housing  110 . Meanwhile, the certain portions of the outer peripheral surface of the buffer  150  contacting with the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  are inwardly pushed by means of the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h , as shown in FIGS. 11 and 12. Furthermore, the inner peripheral surface of the buffer  550  comes in tight contact with the outer peripheral surface of the ink supplying pipe  130 .  
     [0102] The buffer  550  contains the air which is introduced into the housing  110  along the ribs  112   a ,  112   b ,  112   c ,  112   d ,  112   e ,  112   f ,  112   g  and  112   h  while the ink moves through the tip  160  to the substrate. In addition, the buffer  550  stores the ink which is introduced through the slit  134  which is formed in the head portion  132  of the ink supplying pipe  130 , from the reservoir  120  into the buffer  550 . The air stored in the buffer  550  partially moves to the reservoir  120  through the head portion  132  of the ink supplying pipe  130  until the pressure in the housing  110  makes in a state of equilibrium to the atmosphere pressure.  
     [0103] Further, the buffer  550  absorbs and temporarily stores the ink stored in the ink feeder  140  and the tip  160  by the capillarity thereof when the excessive ink is supplied to the ink feeder  140  and the tip  160 .  
     [0104]FIG. 7 is a partially enlarged sectional view of the writing implement  500  according to the fifth embodiment of the present invention, and FIG. 8 is a cross-sectional view of the writing implement  500  according to the fifth embodiment of the present invention, taken along a line D-D′ in FIG. 6.  
     [0105] As shown in FIGS. 7 and 8, the decompression member  570  has a head portion  572 , a rod portion  574  which is integrally formed with the head portion  572  to extend into the ink supplying pipe  130 , a first protrusion  572   a  which is radially formed at a desired distance from one another on a surface of the head portion  572 , and a second protrusion  574   a  which is formed at a desired distance from one another in an axial direction on an outer peripheral surface of the rod portion  574  so as to be connected with the first protrusion  572   a.    
     [0106] The first protrusion  572  of the decompression  570  comes in contact with an upper surface of the head portion  132 , and the second protrusion  574  comes in contact with the inner peripheral surface of the ink supplying pipe  130 . A plurality of grooves is defined between the first protrusions  572   a  and the second protrusions  574   a  of the decompression member  572 , in which the ink flows.  
     [0107] The decompression member  572  guides the ink to flow along the grooves between the first protrusions  572   a  and the grooves between the second protrusions  574   a  when the ink moves into the ink supplying pipe  130 , thereby controlling an amount of the ink introduced into the ink supplying pipe  130 . Furthermore, the decompression member  570  restricts the flow of the ink in a direction indicated by arrows to control the current rate of the ink which is introduced into the ink supplying pipe  130 .  
     [0108]FIG. 10 is a cross-sectional view of the writing implement  100  according to the first embodiment of the present invention, taken along the line A-A′ in FIG. 2 in which a modification of the ink supplying pipe  130  is applied to the writing implement. As shown in FIG. 10, the ink supplying pipe  130 ′ applied to the first embodiment of the present invention includes a head portion  132 ′ having a smaller diameter than the inner diameter of the housing  110 . When the ink supplying pipe  130 ′ is disposed in the housing  110 , a gap  170  having a desired width is defined between an outer peripheral surface of the head portion  132 ′ of the ink supplying pipe  130 ′ and the inner peripheral surface of the housing  110 .  
     [0109] The reservoir  120  is communicated by the gap  170  with the buffer  150 . The air which is introduced into the housing  110  to be stored in the buffer  150 , moves through the gap  170  to the reservoir  120  to compensate the pressure differential between the reservoir  120  and the atmosphere.  
     [0110] It is understood by those skilled in the art that the ink supplying pipe  130 ′ shown in FIG. 10 can be applied to the first embodiment as well as the remaining embodiments of the present invention.  
     [0111]FIG. 14 is an exploded view of an example of the ink supplying pipe  138  applicable to the writing implement according to the first, second, third, fourth and fifth embodiments of the present invention, in which a plurality of through holes  183   a  is formed at a desired distance from one another along the outer peripheral surface of the ink supplying pipe  130 .  
     [0112]FIG. 15 is an exploded view of the other example of the ink supplying pipe  138  applicable to the writing implement according to the first, second, third, fourth and fifth embodiments of the present invention, in which a mesh member  138   b  is installed in the ink supplying pipe  130 .  
     [0113]FIG. 16 is a partially sectional view of a first modification of the ink supplying pipe  130  applicable to the writing implement according to the first, second, third, fourth and fifth embodiments of the present invention. The ink supplying pipe includes a first ink supplying pipe  131  having the head portion as shown in FIG. 9 or  10  and a second ink supplying pipe  133  having the slot  138 , the through holes  138   a , or the mesh member  138   b  as shown in FIG. 13, 14, or  15 . The second ink supplying pipe  133  is disposed between the first ink supplying pipe  131  and the tip  160 . The ink feeder  140  is inserted in the first and second ink supplying pipes  131  and  133 . Where the mesh member  138   b  is installed in the second ink supplying pipe  133 , especially, the mesh member  138   b  is placed in a separate die in which the second ink supplying pipe is molded by injection molding of the synthetic resin.  
     [0114]FIG. 17 is a partially sectional view of a second modification of the ink supplying pipe applicable to the writing implement according to the first, second, third, fourth and fifth embodiments of the present invention. The ink supplying pipe includes a first ink supplying pipe  131 ′ having the head portion shown in FIG. 9 or  10  and a second cylindrical ink supplying pipe  133 ′ having a desired length. A sum of the length of the first ink supplying pipe  131 ′ and the length of the second ink supplying pipe  133 ′ is smaller than the length of the ink supplying pipe  130  shown in FIG. 1 or  16 .  
     [0115] When the ink supplying pipe is disposed in the housing  110 , the ink feeder  140  is inserted in the first and second ink supplying pipes  131 ′ and  133 ′ in the state of spacing at a desired distance between the first and second ink supplying pipes  131 ′ and  133 ′. At this time, the ink feeder  140  is inserted in order that the one end of the ink feeder  140  extends into the first ink supplying pipe  131 ′ and that the other end of the ink feeder  140  is placed on the same plane as the one end of the second ink supplying pipe  133 ′.  
     [0116]FIG. 18 is a sectional view of an intercepting member  180  applicable to the writing implement according to the first, second, third and fourth embodiments of the present invention. As shown in FIG. 18, the intercepting member  180  is disposed between the tip  160  and the one end of the buffer  150  enclosing the one end of the tip  160 , in order to prevent the ink from flowing back from the tip  160  to the buffer  150 . The intercepting member  180  is positioned for the tip  160  not to come in contact with the buffer  150 .  
     [0117] The intercepting member  180  has a truncated conical shape, which has the same inner diameter as that of the tip  160  and the same outer diameter as that of the ink supplying pipe  130 . The intercepting member  180  is disposed in the housing  110  so that a lower portion of the intercepting member  180  comes in contact with the one end of the ink supplying pipe  130  along with the one end of the tip  160 .  
     [0118]FIG. 19 is a sectional view of a first modification of the tip  160  applicable to the writing implement according to the first, second, third, fourth and fifth embodiments of the present invention. As shown in FIG. 19, the tip  160  includes a rod portion  162  having desired length and diameter, and a disc portion  164  radially extending at a predetermined distance from a position adjacent to one end of the rod portion  162 .  
     [0119] The disc portion  164  of the tip  160  has a smaller diameter than the inner diameter of the housing  110 . The tip  160  is disposed in the housing  110  so that the one end of the rod portion  162  comes in contact with the ink supplying pipe  130  and the one end of the ink feeder  140 . The peripheral surface of the disc portion  164  of the tip  160  faces at a desired distance to the inner peripheral surface of the housing  110 .  
     [0120] The disc portion  164  of the tip  160  functions to temporarily receive the leaked ink when the ink is excessively stored in the buffer  550  and it causes the ink to leak from the buffer  550 .  
     [0121]FIG. 20 is a sectional view of a second modification of the tip applicable to the writing implement according to the fifth embodiment of the present invention. As shown in FIG. 20, the tip  160  includes a rod portion  162  having desired length and diameter, and a disc portion  164  radially extending at a predetermined distance from a position adjacent to one end of the rod portion  162 .  
     [0122] The disc portion  164  of the tip  160  has the same diameter as the inner diameter of the housing  110 . The tip  160  is disposed in the housing  110  so that the one end of the rod portion  162  comes in contact with the ink supplying pipe  130  and the one end of the ink feeder  140 . The peripheral surface of the disc portion  164  of the tip  160  comes in contact with the inner peripheral surface of the housing  110 .  
     [0123] The disc portion  164  of the tip  160  functions to temporarily receive the leaked ink when the ink is excessively stored in the buffer  550  and it causes the ink to leak from the buffer  550 .  
     [0124] In the writing implement according to the present invention which is constructed as described above, even though the ink excessively moves to the tip with expansion in response to change of temperature or pressure in the reservoir, the ink feeder and buffer temporarily stores a part of the ink, resulting in regularly supplying the ink to the tip.  
     [0125] While the present invention has been particularly shown and described with reference to a particular embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail may be effected therein without departing from the spirit and scope of the invention as defined by the appended claims.