Patent Publication Number: US-6219077-B1

Title: Printer system

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a printer in which an image is formed or printed on a recording sheet using a thermal head. 
     2. Description of the Related Art 
     Conventionally, several types of printers, using a thermal head to form an image on a recording sheet, are known. One of them is a printer incorporating a thermal head to directly heat a thermal recording sheet, which is a heat sensitive color-developing sheet. The other is a printer in which an ink ribbon is heated so that molten ink is transferred onto a recording sheet. 
     Thus, the conventional printers are not suitably constructed to enable selective, interchangeable use of the materials, which include the thermal recording sheet, the ink ribbon and liquid ink, to suit a given situation. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide a printer system in which the thermal recording sheet, the ink ribbon and the liquid ink, can be selectively used. 
     According to the present invention, there is provided a printer system comprising a thermal printer, an ink transfer unit and a thermal printing unit. The thermal printer includes a thermal head and a platen roller facing each other to define a recording sheet passage therebetween. The ink transfer unit includes a film, having pores, and a plate member facing each other to define an ink storage space. The thermal printing unit includes a holding spool, holding an ink ribbon, a takeup spool, taking up the ink ribbon, and a ribbon passage leading the ink ribbon, unwound from the holding spool, to the takeup spool. 
     The ink transfer unit and the thermal printing unit are selectively mountable on the thermal printer, such that the film faces the recording sheet passage and the plate member faces the thermal head when the ink transfer unit is mounted, and the ribbon passage is positioned between the recording sheet passage and the thermal head when the thermal printing unit is mounted. 
     Preferably, the thermal printer comprises a printer housing and a cover rotatably attached to the printer housing. The platen roller is rotatably supported by the cover. The ink transfer unit and the thermal printing unit are mountable when the cover is open. The printer housing may be provided with a holding member by which the ink transfer unit and the thermal printing unit can be supported. 
     The thermal printing unit may comprise a first frame that supports the holding spool, a second frame that supports the takeup spool, and an intermediate frame that connects the first and second frames. The intermediate frame has an opening through which both surfaces of the ink ribbon are exposed. 
     The thermal printing unit may comprise a moving mechanism by which the takeup spool is rotated. Preferably, the thermal printer comprises a drive mechanism by which the platen roller is rotated. In this construction, the moving mechanism may be connected to the driving mechanism when the thermal printing unit is mounted on the thermal printer. 
     Preferably, the ink ribbon contains a plurality of color ink ribbon portions, each of the plurality of color ink ribbon portions containing differing color ink and being disposed with a predetermined pitch in the longitudinal direction of the ink ribbon. The recording sheet and one of the plurality of color ink ribbon portions are superposed on each other and moved downstream by the pitch so that an image of a first color corresponding to the one of the plurality of color ink ribbon portions is formed. Only the recording sheet is moved upstream by the predetermined pitch, and then the recording sheet and another one of the plurality of color ink ribbon portions are superposed on each other and moved downstream by the pitch so that an image of a second color corresponding to the other one of the plurality of color ink ribbon portions is formed. Thus an image containing the first and second colors is formed. The plurality of color ink ribbon portions may comprise at least three color of ink, so that a full color image is formable. 
     Preferably, the printer system further comprises a sensor that senses the thermal printing unit and the ink transfer unit when mounted on the thermal printer, and a heating unit that heats the thermal head based on a sensing result obtained by the sensor. 
     Furthermore, according to the present invention, there is provided a printer system comprising a thermal printer and an ink transfer unit. The thermal printer includes a thermal head and a platen roller facing each other to define a recording sheet passage therebetween. The ink transfer unit includes a film, having pores, and a plate member facing each other to define an ink storage space. The ink transfer unit is detachably mountable on the thermal printer. 
     The recording sheet is heated and pressed between the thermal head and the platen roller to form an image when the ink transfer unit is not mounted. The film faces the recording sheet passage and the plate member faces the thermal head so that the ink, stored in the ink storage space, is transferred through the pores due to heating by the thermal head to form an image when the ink transfer unit is mounted. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects and advantages of the present invention will be better understood from the following description, with reference to the accompanying drawings in which: 
     FIG. 1 is a perspective view showing a thermal printer of an embodiment of the present invention, with a detached, selectively-mountable thermal printing unit and a detached, selectively-mountable ink transfer unit; 
     FIG. 2 is a side sectional view showing the thermal printer; 
     FIG. 3 is a block diagram showing a control system of the thermal printer; 
     FIG. 4 is a side sectional view showing a state in which the ink transfer unit is mounted on the thermal printer; 
     FIGS. 5 and 6 are schematic views showing a principle by which an image is formed using the ink transfer unit; 
     FIG. 7 is a side sectional view showing a state in which the thermal printing unit is mounted on the thermal printer; 
     FIG. 8 is a perspective view showing a drive system for a platen roller and a takeup spool; 
     FIG. 9 is a plan view showing a multiple-color ink ribbon; 
     FIG. 10 is a plan view showing a recording sheet; and 
     FIG. 11 is a timing chart showing an operation in which a full color image is formed. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a perspective view showing a thermal printer  100 , a thermal printing unit  200  and an ink transfer unit  300 . The units  200  and  300  can be selectively mounted on the thermal printer  100 . 
     The thermal printer  100  has a printer housing  110  and a cover  120 . The printer housing  110  is rectangular parallelepiped or box-shaped and has an opening  101 , which extends in the longitudinal direction of the printer housing  110 . The cover  120  has a pair of support shafts  122  at end portions thereof. The support shafts  122  are inserted in respective bearing portions  112 , which are formed on the printer housing  110 , so that the cover  120  is rotatably supported by the printer housing  110 . 
     A platen roller  130  extends in the longitudinal direction of the cover  120 , and has a pair of support shafts  132  projecting from the end surfaces of the platen roller  130 . The support shafts  132  are rotatably supported by side walls of the cover  120 , so that the platen roller  130  can be rotated about the axis thereof. A platen gear  135  is fixed on one of the support shafts  132 . 
     A drive motor  150  is housed in the printer housing  110 . A motor gear  152  is fixed on an output shaft of the drive motor  150 , and a tip of the motor gear  152  is positioned close to an edge of the opening  101 . An intermediate gear  154  is rotatably mounted in the printer housing  110 , and meshes with the motor gear  152 . A part of the intermediate gear  154  projects outside the printer housing  110 , through a window  111  formed in the housing  110 . 
     When the cover  120  is closed, the platen gear  135  meshes with the motor gear  152 . Therefore, if the drive motor  150  is driven, the motor gear  152  and the platen gear  135  are rotated, and thus the platen roller  130  is rotated. 
     A thermal head  140  is provided in the printer housing  110  and extended in parallel to the platen roller  130 . The thermal head  140  has a slender support board  141  and a heating element  142  formed on the support board  141 . Both end surfaces of the support board  141  are provided with a support shaft  144 , which is rotatably supported by a respective holding frame  160 . Both holding frames  160  are provided in the printer housing  110  and are positioned under the bearing portions  112 , so that the thermal head  140  can pivot about the support shafts  144 . Note that, in the drawing, only one of the holding frames  160  is indicated. 
     In the printer housing  110 , a thermal printing unit  200  and an ink transfer unit  300  can be selectively mounted. First and second unit sensors  171  and  172  are provided in the printer housing  110  to detect whether the thermal printing unit  200  or the ink transfer unit  300  is mounted. The unit sensors  171  and  172  are reflective-type photo sensors, each of which has a light emitting diode radiating a beam, and a light receiving diode sensing the beam reflected by an object. 
     A main switch  116  is provided on an upper surface of the printer housing  110 . When the main switch  116  is pressed once, electric power is supplied to the thermal head  140 , the drive motor  150  and so on. Then, when the main switch  116  is pressed again, the supply of electric power is stopped. On the upper surface of the printer housing  110 , an indicator  117  is provided to indicate an operational state of the thermal printer  100 . 
     The thermal printing unit  200  has a frame  210 , which is composed of a first frame  212 , an intermediate frame  214  and a second frame  216 . The first and second frames  212  and  216  are extended in parallel to each other, and are connected by the intermediate frame  214  in such manner that an opening  201  is formed. Each of the first and second frames  212  and  216  has the same length, which is marginally shorter than the opening  101 , so that the thermal printing unit  200  can be mounted in the printer housing  110 . 
     A holding spool  220  is rotatably supported by the first frame  212 , and a takeup spool  230  is rotatably supported by the second frame  216 . An ink ribbon I is wound around the holding spool  220  and the takeup spool  230 . The ink ribbon I is wound in such a manner that an inner surface of the ink ribbon I, when wound on the holding spool  220  , becomes an outer surface when taken up by the takeup spool  230 . 
     A lower end of the first frame  212  and an upper end of the second frame  216  are positioned at the same height, and the intermediate frame  214  is extended in a horizontal direction therebetween. A ribbon passage is defined by the intermediate frame  214 , and upper and lower surfaces of the ink ribbon I are exposed through the opening  201 . 
     End portions of the takeup spool  230  are projected from the second housing  216 . A takeup gear  232  is fixed on one of the projected portions of the takeup spool  230 , allowing the takeup gear  232  to mesh with the intermediate gear  154  when the thermal printing unit  200  is mounted. 
     A reflection plate  218  is provided on an end surface of the first frame  212 . 
     The thermal printing unit  200  can be inserted into the printer housing  110  when the cover  120  is open. When mounted, the first frame  212  and the intermediate frame  214  are located in the printer housing  110 , and the second frame  216  is disposed outside the printer housing  110 . The intermediate frame  214  is placed on the holding frames  160 , and rear surfaces of the first frame  212  contact vertical surfaces  161  of the holding frames  160 , so that the takeup gear  232  securely meshes with the intermediate gear  154 . Thus, when the drive motor  150  is driven, the takeup spool  230  is rotated through the motor gear  152 , the intermediate gear  154  and the takeup gear  232 . 
     In the state in which the thermal printing unit  200  is properly placed on the holding frames  160 , the reflection plate  218  only faces the first unit sensor  171 , so that the first unit sensor  171  outputs an ON-signal, and the second unit sensor  172  outputs an OFF-signal. 
     Further in this state, the intermediate frame  214  is placed outside of both end portions of the thermal head  140 , and thus the bottom surface of the ink ribbon I can uniformly contact the heating element  142 , and the top surface of the ink ribbon I can be in resilient contact with the platen roller  130 . 
     On the other hand, the ink transfer unit  300  has a rectangular parallelepiped ink reservoir  310 , in which a liquid ink is kept, and a flat beak portion  320 , which is integrally connected to a bottom portion of the ink reservoir  310  and is extended in a horizontal direction. 
     The ink reservoir  310  is marginally shorter than the opening  101  so that the ink transfer unit  300  can be mounted in the printer housing  110 . The ink transfer unit  300  can be inserted into the printer housing  110  when the cover  120  is open, and is placed on the holding frames  160 . In this placing operation, a rear surface of the ink reservoir  310  contacts the vertical surfaces  161  of the holding frames  160 , so that the ink transfer unit  300  is properly positioned in the printer housing  110 . 
     A reflection plate  311  is provided on an end surface of the ink reservoir  310 . When the ink transfer unit  300  is mounted in the printer housing  110 , the reflection plate  311  only faces the second unit sensor  172 , so that the second unit sensor  172  outputs an ON-signal, and the first unit sensor  171  outputs an OFF-signal. 
     FIG. 2 is a side sectional view showing the thermal printer  100 . In a state in which the cover  120  is closed, the platen roller  130  faces the heating element  142  of the thermal head  140 . The support board  141  is urged by a leaf spring  104 , disposed under the support board  141 , to press the heating element  142  against the platen roller  130 . Thus, a thermal recording sheet P is sandwiched between the platen roller  130  and the thermal head  140 . 
     An inlet mouth  125  is formed in the cover  120  so that a recording sheet can be inserted into the printer housing  110 . On the inside of the cover  120 , guide walls  124 ,  126  are formed, so that a guide passage  127  connected to the inlet mouth  125  is defined. The guide walls  124 ,  126  are parallel to each other, and descend at a angle so that a recording sheet is guided to between the platen roller  130  and thermal head  140 . 
     A recording sheet sensor  128  is attached to the guide wall  126 . The recording sheet sensor  128  is a reflective-type photo sensor, which has a light emitting diode emitting a beam, and a light receiving diode sensing the beam reflected by the recording sheet P. Namely, the recording sheet sensor  128  outputs an ON-signal when sensing a recording sheet, and outputs an OFF-signal when not sensing a recording sheet, i.e. when a recording sheet is not inserted in the inlet mouth  125 . 
     An outlet mouth  129  is formed in a front surface (a left side of the printer housing  110  in FIG.  2 ), and is positioned at substantially the same height as the portion of the thermal recording sheet P sandwiched between the platen roller  130  and the thermal head  140 . 
     A battery  106  is provided in the printer housing  110 , to supply electric power to the thermal head  140 , the drive motor  150  and so on, when the main switch  116  is operated. A circuit board  102  is disposed in the printer housing  110 , to control an operation of the thermal printer  100 . 
     FIG. 3 is a block diagram showing a control system of the thermal printer  100 . A control unit C is provided on the circuit board  102 . The thermal printer  100  can be connected to an external device (not shown) through an interface  114  (FIG. 1) provided on an outer surface of the printer housing  110 , allowing image data to be inputted to the thermal printer from the external device. 
     The main switch  116  and the battery  106  are connected to the control unit C to supply electric power to the drive motor  150 , thermal head  140 , the indicator  117 , the interface  114 , the recording sheet sensor  128 , and the unit sensors  171 ,  172 . A signal, which is generated by the unit sensors  171 ,  172  and indicates what unit is mounted in the printer housing  110 , and a signal, which is generated by the recording sheet sensor  128  and indicates whether a recording sheet is inserted or not, are inputted to the control unit C. The thermal head  140  and the drive motor  150  are controlled based on these input signals. 
     An operation, in which only the thermal printer  100  is used to form an image on the thermal recording sheet P, is described below. Namely, in this state, the thermal printing unit  200  and the ink transfer unit  300  are not mounted in the printer housing  110 , so that each of the unit sensors  171 ,  172  outputs an OFF-signal. In accordance with the OFF-signals, the thermal printer  100  is controlled by the control unit C, so that an image is formed on the thermal recording sheet P using only the thermal printer  100 . Note that the thermal recording sheet P is a recording sheet, by which a color is developed due to a specific localized heating. 
     A print start signal and image data are inputted from an external device connected to the interface  114 . When the print start signal is inputted to the control unit C, it is determined in the control unit C whether the recording sheet sensor  128  is sensing the recording sheet P. If the recording sheet sensor  128  is not sensing the recording sheet P, it is deemed that the recording sheet P has not been inserted from the inlet mouth  125 , and thus a message, for example, “NO RECORDING SHEET”, is indicated on the indicator  117 . 
     When the recording sheet sensor  128  senses the recording sheet P, it is deemed that the recording sheet P has been inserted in the inlet mouth  125  and the tip portion of the recording sheet P has reached a portion between the platen roller  140  and the thermal head  140 . Consequently, controls for the drive motor  150  and the thermal head  140  are started, such that the drive motor  150  is rotated and the thermal head  140  is heated. The recording sheet P is pressed with a predetermined pressure between the thermal head  140  and the platen roller  130 , and is fed downstream (leftward in FIG. 2) due to the rotation of the platen roller  130 . Due to this operation, an image is formed on the recording sheet P due to the applied pressure and the heat. When the image has been formed or recorded on the recording sheet P, the recording sheet P is ejected from the outlet mouth  129 . 
     Thus, with only the thermal printer  100 , an image can be formed on the thermal recording sheet P. Note that, if the control unit C is constructed in such a manner that, when each the unit sensors  171 ,  172  outputs an OFF-signals, the thermal head  140  is controlled to heat for a thermal recording operation, a higher quality image can be recorded on the recording sheet. 
     FIG. 4 is a side sectional view showing a state in which the ink transfer unit  300  is mounted in the thermal printer  100 . In this state, the first unit sensor  171  outputs an OFF-signal and the second unit sensor  172  outputs an ON-signal. In accordance with these signals, the thermal printer  100  is controlled by the control unit C, so that an image is formed on the recording sheet P, using the ink transfer unit  300 . 
     The flat beak portion  320  is constructed by superposing a film  322  onto a bottom plate  324 , which is made of a stainless steel, to form an ink space  323  therebetween to hold the liquid ink. The ink space  323  is communicated with the ink reservoir  310  to pass the liquid ink therebetween. Note that the thickness of the bottom plate  324  is 0.01-0.02 mm, enabling the flat beak portion  320  to deform to some extent. 
     When the ink transfer unit  300  is mounted in the thermal printer  100  and the cover  120  is closed, a tip portion of the flat beak portion  320  is sandwiched between the platen roller  130  and the thermal head  140 . In this state, the bottom plate  324  is in contact with the thermal head  140 , and the film  322  contacts the platen roller  130 . A recording sheet P′ inserted in the inlet mouth  125 , is supplied to between the platen roller  130  and the film  322 . 
     FIGS. 5 and 6 are schematic views showing a principle by which an image is formed using the ink transfer unit  300 . As shown in FIG. 5, a hole  325  is formed in the film  322  at a position corresponding to the heating element  142  of the thermal head  140 . The inner diameter of the hole  325  is such that ink cannot pass therethrough in a non-operating state as shown in FIG.  5 . Conversely, when the heating element  142  of the thermal head  140  is heated, ink, positioned in the vicinity of the portion above the heating element  142 , is heated through the bottom plate  324 . Due to this heat, as shown in FIG. 6, the locally heated ink vaporizes, increasing the pressure of the ink on the film  322 . At the same time, the elasticity of the film  322  is locally decreased due to the heat, so that the film  322  becomes relatively deformable. 
     Thus, the ink is urged into and expands the hole  325  formed in the film  322 . Then, the ink passes through the hole  325 , and is transferred onto the recording sheet P′, which is in tight contact with the upper surface of the film  322 . After this transfer, the heating of the heating element  142  is stopped, and thus, the ink and the film  322 , which have been locally heated, are cooled by the surrounding ink, so that the size of the hole  325  returns to the original size, which is small enough to block the ink. Thus, in accordance with predetermined print data, the heating of the heating element  142  is controlled and the platen roller  130  is rotated to feed the recording sheet P′, so that an image is formed by the ink on the recording sheet P′. 
     As described above, by attaching the ink transfer unit  300  to the thermal printer  100 , the ink transfer can be performed to the recording sheet P′, similarly to the printing operation in which only the thermal printer  100  is used for printing an image on the thermal recording sheet P. 
     Note that, if the thermal printer  100  is constructed in such a manner that, when the first unit sensor  171  outputs an OFF-signal and the second unit sensor  172  outputs an ON-signal, the thermal head  140  is controlled by the control circuit C to heat for an ink transfer operation, a higher quality image can be recorded on the recording sheet. 
     FIG. 7 is a side sectional view showing a state in which the thermal printing unit  200  is mounted in the thermal printer  100 . In this state, the first unit sensor  171  outputs an ON-signal and the second unit sensor  172  outputs an OFF-signal. In accordance with these signals, the thermal printer  100  is controlled by the control unit C, so that an image is formed on the recording sheet P′ using the thermal printing unit  200 . 
     The ink ribbon I, which is held on the holding spool  220  and which is taken up by the takeup spool  230 , is in slidable contact with the thermal head  140 , and passes under the recording sheet P′ inserted from the inlet mouth  125 . 
     When the thermal printing unit  200  is correctly placed on the holding frames  160 , and the cover  120  is closed, the platen gear  135  meshes with the motor gear  152 , as shown in FIG.  8 . Further, the motor gear  152  meshes with the intermediate gear  154 , which in turn meshes with the takeup gear  232 . Therefore, by driving the drive motor  150 , each of the motor gear  152 , the platen roller  130  and the takeup spool  230  is rotated in the direction shown by the arrows A, B and C, respectively. 
     The drive motor  150  can be rotated in a downstream direction (shown by the arrow A in the drawing) and an upstream direction. When the drive motor  150  is rotated in the downstream direction, each of the platen roller  130  and the takeup spool  230  is rotated in the directions shown by the arrows B and C, respectively. On the other hand, a one-way clutch  234  is provided between the takeup gear  232  and the takeup spool  230 . Therefore, when the drive motor  150  is rotated in the upstream direction, although the platen roller  130  is rotated in the upstream direction, the takeup spool  230  is not rotated. 
     When using the thermal printing unit  200 , the printing operation selected depends upon whether a monochromatic ink ribbon is used or a multicolored ink ribbon is used. 
     A case, in which the monochromatic ink ribbon is used, is described below. When a print start signal is inputted to the control unit C from an external device, due to the control of the control unit C, the platen roller  130  and the takeup spool  230  are rotated by the drive motor  150 , and the heating element  142  of the thermal head  140  is heated. The recording sheet P′ and the ink ribbon I are pressed with a predetermined pressure between the thermal head  140  and the platen roller  130 , and are moved downstream (leftward in FIG. 7) due to the rotation of the platen roller  130 . 
     The ink ribbon I is heated by the thermal head, so that ink contained in the ink ribbon I is melted by the heat, and is transferred onto a bottom surface of the recording sheet P′. The ink ribbon I is taken up by the takeup spool  230 , and the recording sheet P′ is ejected from the thermal printer  100 , through the outlet mouth  129 . Thus, when a monochromatic ink ribbon is used, an image is recorded on the recording sheet P′ in a printing operation similar to the that in which only the thermal printer  100  is used for printing an image on the thermal recording sheet P. 
     Note that, if the thermal printer  100  is constructed in such a manner that, when the first unit sensor  171  outputs an ON-signal and the second unit sensor  172  outputs an OFF-signal, the thermal head  140  is controlled by the control circuit C, to heat for a thermal printing operation, a higher quality image can be recorded on the recording sheet P′. 
     A case, in which the multicolored ink ribbon is used, is described below. As shown by FIG. 9, the multicolored ink ribbon I is constructed in such a manner that yellow (Y), magenta (M) and cyan (C) ink areas are formed alternately at a predetermined pitch X. Note that a black ink area may be added to the multicolored ink ribbon I. 
     In the case of the thermal printing unit  200  using the multicolored ink ribbon I, a reflection plate (not shown) is disposed on the side surface of the first frame  212  such that the reflection plate is sensed by the first and second unit sensors  171 ,  172 . In this case, each of the first and second unit sensors  171 ,  172  outputs an ON-signal, so that an operation different from the usual printing operation is performed by the control unit C. Namely, the recording sheet P′ is divided into a plurality of sections 1, 2, 3, 4, 5, . . . each of which has the same pitch X as the multicolored ink ribbon I, as shown in FIG. 10, and while the ink ribbon I is moved in the downstream direction, each of the sections of the recording sheet P′ is moved repeatedly downstream and upstream by the number of the colors, so that a color image is formed on the recording sheet P′. 
     FIG. 11 is a timing chart showing an operation of the platen roller  130  and the takeup spool  230 . When the control unit C receives a print start signal from an external device, the drive motor  150  and the thermal head  140  are driven by the control unit C. Namely, the drive motor  150  feeds the recording sheet P′ and the ink ribbon I is moved by the pitch X, so that a yellow image is formed on section 1 of the recording sheet P′. 
     After the yellow image is formed on section 1, the drive motor  150  is reversed by the control unit C, so that the recording sheet P′ is pulled back upstream by the pitch X. At that time, the takeup spool  230  is not rotated due to the one way clutch  234  in FIG. 8, and therefore, the ink ribbon I is not pulled back. Thus, the recording sheet P′ retreats upstream until the front edge of section 1 coincides with the front edge of the magenta ink area. Then, the drive motor  150  is rotated forward again, and a magenta image is formed on section 1 of the downstream-moving recording sheet P′. 
     In the same way as above, a cyan image is formed on section 1. Thus, a full color image composed of yellow, magenta and cyan images is formed on the recording sheet P′. Note that, after the cyan image is formed on section 1, the forward rotation of the drive motor  150  is continued, allowing the above process to be repeated for forming a full color image on section 2 of the recording sheet P′. 
     As described above, when the thermal printing unit  200  is mounted in the thermal printer  100 , a monochromatic image and a multicolored image can be formed. Note that, if the heating element  142  is controlled in accordance with a full color thermal printing operation, a higher quality image can be formed. 
     According to the embodiment of the present invention, by using only the thermal printer  100 , an image can be formed on the thermal recording sheet P, and when the ink transfer unit  300  is mounted in the thermal printer  100 , liquid ink can be transferred onto the recording sheet P′. Further, when the thermal printing unit  200  is mounted in the thermal printer  100 , the ink ribbon is heated so that ink contained in the ink ribbon is melted and also transferred onto the recording sheet P′. 
     Although the embodiments of the present invention have been described herein with reference to the accompanying drawings, obviously many modifications and changes may be made by those skilled in this art without departing from the scope of the invention. 
     The present disclosure relates to subject matter contained in Japanese Patent Application No. 9-304989 (filed on Oct. 20, 1997) which is expressly incorporated herein, by reference, in its entirety.