PATENT ABSTRACT
An ink ribbon cartridge includes an ink replenishing configuration. An ink ribbon is housed in a housing. An ink replenishing member replenishes ink into the ink ribbon. An ink storing member holds a supply of the ink, the ink storing member being movable either to a first position where the ink storing member contacts the ink replenishing member and supplies the ink to the ink replenishing member or a second position where the ink storing member does not contact the ink replenishing member and does not supply the ink to the ink replenishing member.

PATENT DESCRIPTION
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an ink supplying mechanism for an ink ribbon incorporated in printing apparatuses including a serial dot impact printer. 
         [0003]    2. Description of the Related Art 
         [0004]    Some conventional dot impact printers incorporate an ink ribbon cartridge equipped with an ink supplying mechanism.  FIG. 16  illustrates one such printer disclosed by Japanese Patent Laid Open No. H08-192560. Referring to  FIG. 16 , a conventional dot impact printer is equipped with an ink ribbon cartridge  112 D that holds an endless type ink ribbon  111  impregnated with a liquid ink. A printhead  113  is mounted on a carriage unit  115 . The ink ribbon  111  extends through a gap between a printhead  113  and paper  114 . The wires (not shown) of the printhead  113  impact the ink ribbon  111  to print on the paper  114 . 
         [0005]    The amount of ink (not shown) in the ink ribbon  11  decreases as printing is carried on. An ink tank  120  supplies the ink to the ink ribbon  111 . 
         [0006]    The carriage unit  115  is driven by a spacing motor  116  and pulleys  117   a  and  117   c  to move leftward and rightward reciprocally across the paper  114 . 
         [0007]    A spacing belt  116  is disposed about the pulleys  117   a  and  117   c . The carriage unit  115  is fixed to the spacing belt  116 . The spacing motor  116  rotates to cause the carriage unit  115  to move in directions shown by arrows A and B. The ink ribbon cartridge  112 D is fixed to side frames  119   a  and  119   b , and accommodates an ink tank  120  with an ink replenishing strip  121  in contact with the ink ribbon  111 . Thus, the ink is directed from the ink tank  120  to the ribbon  111  by capillary action. 
         [0008]    A transfer roller  122  is in rotatable contact with the ink replenishing strip  121 . A drive roller  123  rotates in pressure contact with the transfer roller  122  so that when the drive roller  123  rotates, the transfer roller  122  will also rotate. When printing is performed, the spacing motor  116  drives the carriage unit  115  to move leftward and rightward so that the printhead  113  moves across the paper  114 . 
         [0009]    The pulleys  117   a  and  117   b  are mounted on the shaft of the spacing motor  116 . The pulley  117   b  includes gear teeth in mesh with a gear  124   a , which in turn is in mesh with a gear  124   b . When the ink ribbon cartridge is attached to the printer, the gear  124   b  moves into meshing engagement with a drive shaft located on a body of the dot impact printer. The drive shaft fits in a drive roller  123  so that the drive shaft is concentric to the drive roller  123 . The spacing motor  116  drives the pulley  117   b , gear  124   a , and gear  124   b  to rotate, thereby driving the drive roller  123  in rotation. 
         [0010]    Thus, the ink ribbon  111  advances through a gap between the transfer roller  122  and the drive roller  123 . The ink replenishing strip  121  is in pressure contact with the transfer roller  122 . 
         [0011]    The ink is supplied from the ink tank  120  to the transfer roller  122  through the ink replenishing strip  121 . Then, the ink is transferred onto the ink ribbon  111  from the transfer roller  122 . In this manner, the ink is replenished to the ink ribbon  111 . 
         [0012]    However, the ink replenishing strip  121  of the aforementioned conventional configuration is in contact with the transfer roller  122  at all times. Therefore, if the ink ribbon cartridge  112 D is left unused for a long period of time, an excess amount of ink stays only at an area where the transfer roller  122  is in contact with the replenishing strip  121 . The ink ribbon  111  that has absorbed excess ink will result in uneven density of printed images such as spread of ink at the beginning of a new printing operation shortly after replacement of the ink ribbon cartridge  112 D, which shortens the useable life time of the ink ribbon cartridge  112 D due to excess initial density of printed characters. 
       SUMMARY OF THE INVENTION 
       [0013]    An object of the invention is to provide an ink ribbon cartridge capable of preventing an excess amount of ink from staying at an area in which an ink replenishing member is in contact with a transfer roller even if the ink ribbon cartridge is left unused for a long period of time. 
         [0014]    An ink ribbon cartridge includes an ink replenishing configuration. An ink ribbon is housed in a housing. An ink replenishing member replenishes ink into the ink ribbon. An ink storing member holds a supply of the ink, being movable either to a first position where the ink storing member contacts the ink replenishing member and supplies the ink to the ink replenishing member or a second position where the ink storing member does not contact the ink replenishing member and does not supply the ink to the ink replenishing member. 
         [0015]    Another ink ribbon cartridge includes an ink replenishing configuration. A roller rotates to advance an ink ribbon. An ink replenishing member is in contact with the roller, the ink replenishing member supplying ink to the roller via the roller. A blocking member is in sandwiched engagement with the roller and the ink replenishing member such that the blocking member is held between the roller and the ink replenishing member, the blocking member blocking supply of ink from the ink replenishing member to the roller, the blocking member being fixed at its one end to a housing. An urging member urges the blocking member in such a direction as to be away from the roller and the ink replenishing member. The blocking member is in friction contact with a part of the roller until the blocking member is worn out to cut off. When the blocking member is worn out to cut off, the urging member pulls the blocking member out of the sandwiched engagement. 
         [0016]    A printer includes the aforementioned ink ribbon cartridge. A drive mechanism causes the ink storing member to move into contact engagement with the ink impregnable. A controller meters an amount of ink consumed during printing, metering being started for a first printing operation shortly after a new, unused ink ribbon cartridge is attached to an apparatus. The drive mechanism exerts the external force on the ink storing member when the controller detects that the amount of ink consumed reaches a predetermined value. 
         [0017]    Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limiting the present invention, and wherein: 
           [0019]      FIG. 1  illustrates the configuration of an ink ribbon cartridge and a printing apparatus of a first embodiment; 
           [0020]      FIG. 2  is a cross-sectional view of a pertinent portion of the ink ribbon cartridge taken along a line A-A of  FIG. 1 ; 
           [0021]      FIG. 3  is a top view of the ink replenishing strip coupled to an upper ink tank; 
           [0022]      FIG. 4  is a cross sectional view taken along a line B-B of  FIG. 5 , and illustrates a pertinent portion of the ink ribbon cartridge; 
           [0023]      FIG. 5  illustrates the general configuration of an ink ribbon cartridge and a printer of a second embodiment; 
           [0024]      FIG. 6  is a cross sectional view taken along the line B-B of  FIG. 5 , and illustrates a pertinent portion of the ink ribbon cartridge; 
           [0025]      FIG. 7  is a top view of a pertinent portion of the second embodiment; 
           [0026]      FIG. 8  is a block diagram illustrating the control system of the printer of the second embodiment; 
           [0027]      FIG. 9  illustrates the operation of the ink ribbon cartridge of the second embodiment; 
           [0028]      FIGS. 10A and 10B  are a flowchart illustrating the operation of a print controller of the second embodiment; 
           [0029]      FIG. 11  illustrates a general configuration of an ink ribbon cartridge and a printer of a third embodiment; 
           [0030]      FIG. 12  is a cross-sectional view taken along a line C-C of  FIG. 11 , illustrating a pertinent portion of the ink ribbon cartridge; 
           [0031]      FIG. 13  is a perspective view illustrating a shutter and the ink ribbon cartridge of  FIG. 11 ; 
           [0032]      FIG. 14  illustrates the operation of the ink ribbon cartridge of the third embodiment; 
           [0033]      FIG. 15  illustrates the operation of the ink ribbon cartridge of the third embodiment; and 
           [0034]      FIG. 16  illustrates a conventional printer. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    Embodiments of the present invention will be described with reference to the accompanying drawings. Like elements have been given like reference numerals throughout the drawings. 
       First Embodiment 
     Construction 
       [0036]      FIG. 1  illustrates the configuration of an ink ribbon cartridge and a printing apparatus of a first embodiment. Referring to  FIG. 1 , a carriage unit  115  is fixed to a portion of a spacing belt  118 , and supports a printhead  113  thereon. 
         [0037]    Pulleys  117   a  and  117   b  are mounted to a drive shaft (not shown) of a spacing motor  116  and configured to rotate on the drive shaft. When the spacing motor  116  is energized, the spacing motor  116  drives the spacing belt  118  to rotate so that the carriage unit  15  and printhead  113  move in directions shown by arrows A and B. 
         [0038]    The pulley  117   b  is in mesh with a gear  124   a  which in turn is in mesh with a gear  124   a . The gear  124   b  is coupled to another drive shaft which is concentric to the drive roller  123  in the ink ribbon cartridge  112 A. Once a user has attached the ink ribbon cartridge  112 A to side frames  119   a  and  119   b , the drive roller  123  is in coupling engagement with the drive shaft (not shown). 
         [0039]    Thus, when the space motor  116  is energized, the drive shaft is driven in rotation via the pulley  117   b  and gears  124   a  and  124   b , causing the drive roller  123  in the ink ribbon cartridge  112 A to rotate. Thus, the ink ribbon  11  is advanced while being sandwiched between the transfer roller  122  and the drive roller  123 . 
         [0040]      FIG. 2  is a cross-sectional view of a pertinent portion of the ink ribbon cartridge  112 A taken along a line A-A of  FIG. 1 .  FIG. 3  is a top view of the upper ink tank  120   a  and ink replenishing strip  121  coupled to the upper ink tank  120   a . Referring to  FIG. 2 , a box-like housing  125  of the ink ribbon cartridge  112 A is formed of a synthetic resin, and opens at one widthwise end portion of the ink ribbon cartridge  112 A. A lid or a cover  126  of the ink ribbon cartridge  112 A is formed of a synthetic resin, and covers an opening formed in the housing  125  of the ink ribbon cartridge  112 A. 
         [0041]    The cover  126  includes a supporting member  126   z  formed in one piece with the cover  126 . The upper ink tank  120   a  is generally rectangular box-shaped, and accommodates an ink impregnable member  120   d  having the replenishing strip  121  connected at its one end. The supporting member  126   z  extends through the upper ink tank  120   a  so that the upper ink tank  120   a  is held in position in the ink ribbon cartridge  125  with the ink replenishing strip  121  in contact with the transfer roller  122 . 
         [0042]    The ink impregnable member  120   d  is supported between retaining ribs  140  ( FIG. 3 ) in a sandwiched relation. An ink storage medium  127  is disposed below the retaining ribs  140 , and is accommodated in a lower ink tank  120   b . The ink impregnable member  120   d  includes a hole through which the supporting member  126   z  extends. The ink storage medium  127  includes a hole through which a hollow cylindrical portion  120   c  extends. The ink storage medium  127  receives the supporting member  126   z.    
         [0043]    The ink impregnable member  120   d  is in the form of non-woven fabric, textile fabric, sponge, or the like, and is not impregnated with ink before it is unsealed. The ink storage medium  127  is in the form of non-woven fabric, textile fabric, sponge, or the like. The ink replenishing strip  121  is in the form of felt which is highly resilient and highly impregnable. The ink storage medium  127  is not in contact with the ink impregnable member  120   d  before it is unsealed. 
         [0044]    The supporting member  126   z  extends through a spring  128  disposed between the upper ink tank  120   a  and the lower ink tank  120   b . The lower ink tank  120   b  and upper ink tank  120   a  are urged by the spring  128  in directions away from each other. Thus, the ink tank  120   b  and ink tank  120   a  will not contact with each other. 
         [0045]    A cylindrical push-up rib  135  is disposed on a body of a printer such that the push-up rib  135  is concentric to the supporting member  126   z.    
       {Operation} 
       [0046]      FIG. 4  is a cross sectional view taken along a line A-A of  FIG. 5 , and illustrates a pertinent portion of the ink ribbon cartridge. The operation of the ink ribbon cartridge of the aforementioned configuration and the printer will be described with reference to  FIG. 4 . 
         [0047]    When an operator attaches the ink ribbon cartridge  112 A to side frames  119   a  and  119   b , the push-up rib  135  pushes up the lower ink tank  120   b  in a direction shown by arrow D, so that the ink storage medium  127  is brought into pressure contact with the ink impregnable member  120   d  held in the upper ink tank  120   a.    
         [0048]    The ink impregnable member  120   d  draws by capillary action the ink from the ink storage medium  127  in a direction shown by arrow H. The configurations (i.e., materials and structures) of the ink storage medium  127 , ink impregnable member  120   d , and ink replenishing strip  121  are such that t 1 ≅t 2  where t 1  is an average time required for the ink in the ink ribbon  111  to be consumed during printing and t 2  is an amount of time required for the ink held in the ink storage medium  127  to reach the transfer roller  122  through the ink replenishing strip  121  and the ink impregnable member  120   d . This ensures that the ink storage medium  127  supplies the fresh ink only by an amount actually consumed during printing. 
         [0049]    When the printer receives a print command from a host apparatus, a controller in the printer drives the spacing motor  116  to cause the carriage unit  115  to move leftward and rightward across the paper, so that the printhead  113  performs printing. The spacing motor  116  also drives the pulley  117   b  and the gears  124   a  and  124   b  for rotation, thereby causing the drive shaft (not shown) to rotate, so that the drive roller  123  in the ribbon cartridge  112 A rotates to advance the ink ribbon  111  held between the transfer roller  122  and drive roller  123  in sandwiched relation. 
         [0050]    The ink starts to be replenished into the ink ribbon  111  only after the ink ribbon  111  has made several complete revolutions in one direction. Therefore, an appropriate amount of ink may be supplied to the ink ribbon  111 . 
       {Advantages} 
       [0051]    As described above, the ink tank includes the upper ink tank  120   a  and the lower ink tank  120   b . The upper ink tank  120   a  includes the ink replenishing strip  121  and ink impregnable member  120   d  while the lower ink tank  120   b  accommodates the ink storage medium  127  therein. When the ink ribbon cartridge  112 A has been attached to the printer, the lower ink tank  120   b  has moved into abutting engagement with the upper ink tank  120   a  so that the ink storage medium  127  is brought into pressure contact with the ink impregnable member  120   d  to supply the ink to the ink ribbon  111  through the ink replenishing strip  121  and transfer roller  122 . This configuration is effective in preventing the ink from staying at an area where the ink replenishing strip  121  is in pressure contact with the transfer roller  122 . 
         [0052]    The configuration makes efficient use of the ink because the time required for the ink in the ink ribbon  111  to be exhausted is substantially equal to the time required for the ink to be supplied from the ink storage medium  127  to the ink ribbon  111  via the ink impregnable member  120   d , ink replenishing strip  121 , and transfer roller  122 . 
       Second Embodiment 
       [0053]      FIG. 5  illustrates the general configuration of an ink ribbon cartridge  112 B and a printer of a second embodiment. Elements similar to those in the first embodiment have been given the same reference numerals and their description is omitted. 
         [0054]      FIG. 6  is a cross sectional view taken along a line B-B of  FIG. 5 , and illustrates a pertinent portion of the ink ribbon cartridge  112 B. Hooks  120   c  are formed in a lower ink tank  120   b . When the lower ink tank  120   b  moves toward an upper ink tank  120   a , the hooks  120   c  move into hooking engagement with engagement portions  120   e  formed on the upper ink tank  120   a.    
         [0055]      FIG. 7  is a top view of a pertinent portion of the second embodiment. 
         [0056]    Referring to  FIG. 7 , a carriage unit  115  includes a projection  115   b  at its lower end portion. The lower ink tank  120   b  is disposed in the path of the projection  115   b  so that an inclined surface  115   a  of the projection  115   b  engages the bottom of the lower ink tank  120   b  when the carriage unit  115  moves in a direction shown by arrow A ( FIG. 5 ). The carriage unit  115  moves further a predetermined distance L after it abuts the bottom of the lower ink tank  120   b  so that the inclined surface  115   a  enters under the lower ink tank  120   b  pushing the lower ink tank  120   b  out of the way and an ink storage medium  127  toward the upper ink tank  120   a . Thus, the ink storage medium  127  moves into pressure contact with the ink impregnable member  120   d  in the upper ink tank  120   a.    
         [0057]    The carriage unit  115  is controlled in its movement so that the projection  115   b  will not interfere with the lower ink tank  120   b  during the normal printing operation. A side frame  119   b  includes a sensor  129  mounted thereto. The sensor  129  detects when the ink ribbon cartridge  112 B is attached to the printer. 
         [0058]      FIG. 8  is a block diagram illustrating the control system of the printer of the second embodiment. A spacing mechanism  134  drives under control of a controller the carriage unit  115  to move in directions shown by arrows A and B in  FIG. 5 . A wire driver mechanism  132  receives a control command from a head driver  131 , and drives printing wires under control of the control command. 
         [0059]    The consumed amount of ink in the ink ribbon  111  is proportional to the number of printed dots. A counter  133  counts the cumulative number of times the printing wires are driven, thereby metering an amount of ink consumed during printing. The counter  133  starts counting for a first printing operation shortly after a new, unused ink ribbon cartridge is attached to an apparatus. When the count of the counter  133  reaches a predetermined value, the carriage unit  115  is displaced against the ink tank  120   b  by a predetermined distance L so that the lower ink tank  120   b  is pushed by the inclined surface  115   a  out of the way. Thus, the ink storage medium  127  is brought into pressure contact with the ink impregnable member  120   d.    
       {Operation} 
       [0060]      FIGS. 10A and 10B  are a flowchart illustrating the operation of print controller of the second embodiment. The operation of the ink ribbon cartridge  112  and printer of the aforementioned configuration will be described with respect to  FIGS. 5 ,  9 , and  10 A- 10 B. 
         [0061]    Upon power-up of the printer, a spacing motor  116  drives the carriage unit  115  to take up a starting position in the A and B directions in  FIG. 5 . 
         [0062]    First, the carriage unit  115  moves in the A direction. When a starting position sensor (not shown) detects the carriage unit  115 , the space motor  116  runs in the reverse direction so that the carriage unit  115  moves in the B direction until the carriage unit  115  takes up a predetermined position. 
         [0063]    A sensor  129  disposed on the side frame  119   b  detects the ink ribbon cartridge  112 B (S 01 A). If the sensor  129  fails to detect the ink ribbon cartridge  112 B (N at S 01 A), the sensor  129  generates an alarm signal prompting a user to attach the ink ribbon  112 B to the printer (S 01 B). If the sensor  129  detects the ink ribbon cartridge  112 B (Y at S 01 A), the controller  130  determines that the printer is ready for printing. 
         [0064]    The controller  130  sets a value to the counter  133  incorporated in a circuit (not shown), the value corresponding to an amount of ink in the ink ribbon  111  (S 02 ). The controller  130  starts printing upon receiving print data, and causes the counter  133  to count down by “1” during printing every time a dot is printed. Printing is started (S 03 ). Thus, an amount of ink of the ink ribbon  111  consumed during printing may be detected in terms of the count of the counter  133 . (S 04 ). 
         [0065]    The spacing motor  116  drives the pulleys  117   b  and gears  124   a  and  124   b  to rotate, causing a drive shaft (not shown) to rotate, so that the drive roller  123 , coupled to the drive shaft, in the ink ribbon cartridge  112 B rotates. 
         [0066]    As a result, the transfer roller  122  and the drive roller  123  cooperate with each other to advance the ink ribbon  111  held therebetween. At this moment, the upper ink tank  120   a  is not in locking engagement with the lower ink tank  120   b  so that the ink is not supplied from the ink storage medium  127  to the ink ribbon  111  via the ink impregnable member  120   d . Thus, printing is performed using only the ink in the ink ribbon  111 . 
         [0067]    When the count of the counter  133  reaches a predetermined value due to printing (S 05 ), the controller  130  determines that the ink in the ink ribbon  111  has been consumed completely, and then causes the carriage unit  115  to move in the A direction by a distance of L mm from a normal stop position (S 06 ). Then, the controller  130  controls the carriage unit  115  to halt under the ink tank  120   b  for Δt seconds (S 07 ). 
         [0068]    The amount of movement of the carriage unit  115  is a distance L from an end of the stroke of the carriage unit  115  shown in  FIG. 6 . The movement of the carriage unit  115  by a distance L in the A direction causes the lower ink tank  120   b  to move toward the upper ink tank  120   a , so that the hooks  120   c  engage the engagement portions  120   e . Once the hooks  120   c  engage the engagement portions  120   e , the lower ink tank  120   b  remains locked to the upper ink tank  120   a . Thus, the carriage unit  115  needs to enter under the lower ink tank  120   b  for a very short time, i.e., only about 0.5 to 1.0 second. 
         [0069]      FIG. 9  illustrates the operation of an ink ribbon cartridge  112 B of the second embodiment. 
         [0070]    Referring to  FIG. 9 , the inclined surface  115   a  on the carriage unit  115  causes the lower ink tank  120   b  and the ink storage medium  127  to move toward the upper ink tank  120   a , so that the lower ink tank  120   b  is in pressure contact with the upper ink tank  120   a  and the ink storage medium  127  is in contact with the ink impregnable member  120   d.    
         [0071]    The ink in the ink storage medium  127  is drawn by capillary action in the H direction ( FIG. 9 ). The ink is supplied to the transfer roller  122  via the ink impregnable member  120   d  and the ink replenishing strip  121 . The ink replenishing strip  121  in turn supplies the ink to the ink ribbon  111 . 
         [0072]    In this manner, the ink is replenished from the ink storage medium  127  after a certain amount of ink held in the ink ribbon  111  has been consumed. Then, printing is resumed (S 08 ). 
         [0073]    The controller  130  again sets a value to the counter  133 , the value corresponding to the amount of ink held in the ink storage medium  127  (S 11 ). Thereafter, the controller  130  controls the counter  133  to again count down every time a dot is printed (S 12 ). 
         [0074]    As described above, the amount of ink in the ink storage medium  127  consumed by the printhead  113  may be measured by counting the number of printed dots. When the count of the counter  133  reaches a predetermined value (S 13 ), the controller  130  determines that the ink in the ink storage medium  127  has been used up, and then halts printing (S 14 ) and displays a message to the operator prompting replacement of the ink ribbon cartridge (S 15 ). 
       {Advantages} 
       [0075]    As described above, the ink tank includes the upper ink tank  120   a  and the lower ink tank  120   b . The upper ink tank  120   a  holds the ink replenishing strip  121  and the ink impregnable member  120   d  while the lower ink tank  120   b  accommodates the ink storage medium  127  therein. The carriage unit  115  includes the inclined surface  115   a  that pushes the lower ink tank  120   b  and an ink storage medium  127  toward the upper ink tank  120   a , so that when the count of the counter  133  reaches a predetermined value due to printing, the inclined surface  115   a  causes the lower ink tank  120   b  to move to the upper ink tank  120   a . Thus, the amount of ink consumed from the ink ribbon  111  may be accurately detected, allowing the ink to be replenished to the ink ribbon  111  at an appropriate timing after the ink in the ink ribbon  111  has been used up. 
       Third Embodiment 
       [0076]      FIG. 11  illustrates a general configuration of an ink ribbon cartridge  112 C and a printer of a third embodiment.  FIG. 12  is a cross-sectional view taken along a line C-C of  FIG. 11 , illustrating a pertinent portion of the ink ribbon cartridge  112 C.  FIG. 13  is a perspective view illustrating a shutter  137  and the ink ribbon cartridge  112 C. 
         [0077]    The shutter  137  is formed of an amorphous resin material which is easy to wear out as compared to other types of synthetic resins, and is held between an ink replenishing strip  121  and a transfer roller  122  in sandwiched relationship. The shutter  137  is mounted by inserting in a direction shown by arrow Y (FIG.  13 ) into slits  125   a  and  125   b  formed in housing  112 C of the ink ribbon cartridge. 
         [0078]    Referring to  FIGS. 14 and 15 , a tension spring  135  urges the shutter  137  at all times in a direction shown by arrows Z. An end portion  137   a  of the shutter  137  projects into the slit  125   a  so that the shutter  137  is held in position relative to the housing  125 . 
         [0079]    A longitudinal end portion of the shutter  137  extends through a gap between the ink replenishing strip  121  and a transfer roller  122 , so that supply of the ink from the ink tank  120  is interrupted. The transfer roller  122  includes a flange  122   a  which is in contact with a wear portion  137   a  of the shutter  137  shown in  FIG. 13 . 
       {Operation} 
       [0080]      FIG. 14  illustrates the operation of an ink ribbon cartridge  112 C of the third embodiment.  FIG. 15  illustrates the operation of an ink ribbon cartridge  112 C of the third embodiment. 
         [0081]    The operation of the ink ribbon cartridge  112 C and printer of the aforementioned configuration will be described with reference to  FIGS. 14 and 15 . 
         [0082]    When the printer receives a print command, the controller  130  controls a spacing motor  116  to cause a carriage unit  115  and a printhead  113  to move across the paper for performing printing. 
         [0083]    The spacing motor  116  also drives a pulley  117   b  and gears  124   a  and  124   b , thereby driving a drive shaft (not shown) to rotate so that a drive roller  123  in the ink ribbon cartridge  112 C rotates. 
         [0084]    As a result, the transfer roller  122  and drive roller  123  cooperate with each other to cause the ink ribbon  111  sandwiched between them to advance. Because the shutter  137  prevents the ink from being delivered from the ink replenishing strip  121  to the transfer roller  122 , printing is performed only using the ink in the ink ribbon  111  shortly after a new, unused ink ribbon cartridge has been attached to the printer. 
         [0085]    When the carriage unit  115  moves in the spacing direction, the transfer roller  122  rotates. Because the flange  122   a  of the transfer roller  122  is in contact with the shutter  137 , the flange  122   a  starts to cause the wear portion  137   a  of the shutter  137  to wear. 
         [0086]    The thickness of the shutter  137  is selected such that t 1 ≅t 3  where t 1  is an average amount of time required for the ink in the ink ribbon  111  to be used up during printing and t 3  is an amount of time required for the wear portion  137   a  to completely wear out and cut off. 
         [0087]    Referring to  FIGS. 14 and 15 , the tension spring  135  holds the shutter  137  is in tension. The shutter  137  moves in the Z direction when the wear portion  137   a  is cut off. As a result, the ink replenishing strip  121  moves into pressure contact with the transfer roller  122 , so that the ink in the ink storage medium  127  starts to be supplied to the transfer roller  122  through the ink replenishing strip  121 . The ink is transferred from the transfer roller  122  onto the ink ribbon  111 . The ink ribbon passes through a gap between the transfer roller  122  and the drive roller  123 . 
       {Advantages} 
       [0088]    As described above, a portion of the shutter  137  is sandwiched between the ink replenishing strip  121  and the transfer roller  122 , and is urged in a predetermined direction by the spring  135 . When the portion of the shutter  137  sandwiched between the transfer roller  122  and the ink replenishing strip  121  has completely worn out, the shutter  137  is pulled out of the gap between them. This configuration eliminates the need for providing the combination of the upper ink tank  120   a  and the lower ink tank  120   b , and providing an electromechanical driving mechanism for counting the number of printed dots and for moving the upper and lower ink tanks. The third embodiment provides a simple solution in which the ink may be replenished whenever the ink in the ink ribbon has been exhausted. 
         [0089]    The invention has been described with respect to a configuration in which an ink replenishing strip is in pressure contact with a transfer roller in the vicinity of a portion through which the ink ribbon is advanced from the ink ribbon cartridge so that the ink is replenished to the ink ribbon. However, the ink may also be replenished in the vicinity of a portion through which the ink ribbon enters the ink ribbon cartridge. 
         [0090]    The invention may be applied not only to serial dot printers but also to type writers and printer that employ an ink ribbon cartridge equipped with an ink replenishing mechanism.