Patent Publication Number: US-9421792-B2

Title: Printing apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a printing apparatus, and more particularly, to a printing apparatus provided with a thermal head. 
     BACKGROUND ART 
     Conventionally, such a printing apparatus has been known widely that forms an image on a printing medium using a thermal head. This type of printing apparatus uses an indirect printing scheme for forming an image (mirror image) on a transfer film using an ink ribbon, and next transferring the image formed on the transfer film to a printing medium, or a direct printing scheme for forming an image directly on a printing medium using an ink ribbon. 
     Generally, in such a printing apparatus are inserted an ink ribbon cassette storing an ink ribbon (film-shaped medium) laid between a supply spool and a wind-up spool, and similarly, a transfer film cassette storing a transfer film (film-shaped medium) laid between a supply spool and a wind-up spool. 
     In this type of printing apparatus, such a technique is disclosed that a certain tension is added to the ink ribbon corresponding to a variation in the diameter (roll diameter) of the ink ribbon wound around the spool (for example, see Patent Document 1). 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         [Patent Document 1] Japanese Patent Application Publication No. H08-2078 (see FIG. 1 and paragraph [0090]) 
       
    
     DISCLOSURE OF INVENTION 
     Problems to be Solved by the Invention 
     In addition, in order to ensure image quality, as in the invention of Patent Document 1, it is necessary to make the tension relative to the film-shaped medium a certain corresponding to a variation in the roll diameter, but since torque of a DC motor itself varies with the environmental temperature, age deterioration and the like of the DC motor, it is difficult to always provide the film-shaped medium with a certain tension even in controlling the DC motor corresponding to the roll diameter. 
     As the solution, it is conceivable to measure a rotation velocity of the DC motor with respect to a predetermined current at constant frequencies, calculate a difference between the velocity and a reference rotation velocity, and correct a supply current (duty) to the DC motor. However, in a mechanism in which a plurality of DC motors transport the film-shaped medium as disclosed in Patent Document 1, in measuring the rotation velocity of the DC motor, when the film-shaped medium is in a state in which the tension is applied to the film-shaped medium, the effect due to the tension of the film-shaped medium is exerted, it is thereby not possible to obtain a correct measurement value of the rotation velocity of the DC motor, and it is not possible to properly correct the supply current to the DC motor. In other words, although the correction due to the variation of the roll diameter has conventionally been made, it is not possible to obtain the correct tension of the film-shaped medium unless the DC motor as a base is corrected properly, and there is a problem that the image quality deteriorates. 
     In view of the above-mentioned matters, it is an object of the present invention to provide a printing apparatus capable of preventing the image quality from deteriorating, by correcting a supply current to a DC motor properly. 
     To attain the above-mentioned object, in the present invention, a printing apparatus provided with a printing section to print text or an image on a printing target medium from a film-shaped medium is characterized by being provided with a supply spool that feeds out a film-shaped medium to the printing section side in printing processing, a wind-up spool that winds up the film-shaped medium from the printing section side in the printing processing, a DC motor that rotates at least one of the supply spool and the wind-up spool, a motor driver that supplies a drive current to the DC motor, a rotation amount detector that detects a rotation amount of the DC motor, and a controller that controls the motor driver, where the controller calculates a drive current to be supplied to the DC motor for providing DC motor with the same rotation velocity as a rotation velocity of a reference DC motor driven with the same drive current in driving the DC motor without the tension due to the film-shaped medium being applied, and controls the motor driver to supply the calculated drive current. 
     In the invention, since the DC motor generates a difference in the rotation velocity according to the rotation direction, in driving the DC motor without the tension due to the film-shape medium being applied, it is preferable that the controller drives in the same direction as the rotation direction of the DC motor for transporting the film-shaped medium from the supply spool side to the wind-up spool side. Further, the controller may drive the DC motor without the tension due to the film-shaped medium being applied, calculate a rotation velocity of the DC motor based on the rotation amount of the DC motor detected in the rotation amount detector, refer to the relationship between the rotation velocity and the supply current in the reference motor, calculate a supply current of the DC motor for providing the same rotation velocity as a rotation velocity of the time the reference motor is driven with the supply current at the calculated rotation velocity, and control the motor driver to supply the calculated supply current. 
     Further, before the printing processing with the thermal head, the controller may drive the DC motor with the film-shaped medium sagged to calculate the rotation velocity of the DC motor. 
     The apparatus is further provided with a mark detector that detects an empty mark indicative of a use limit of the film-shaped medium attached to an end portion of the film-shaped medium, and after the mark detector detects the empty mark, the control may drive the DC motor with the film-shaped medium sagged to calculate the rotation velocity of the DC motor. At this point, the apparatus is further provided with a nonvolatile memory, and the controller may store the calculated value of supply current in the nonvolatile memory, reads the value of supply current stored in the nonvolatile memory after replacing the film-shaped medium with a new film-shaped medium, and control the motor driver to supply the supply current with the read value of supply current. 
     Moreover, the apparatus is further provided with a temperature detector that detects an ambient temperature of the DC motor, and the controller may apply the calculated rotation velocity to a beforehand determined relationship between the rotation velocity and the temperature to make a temperature correction to the rotation velocity at a predetermined temperature. 
     Further, the DC motor is comprised of a first DC motor that rotates the supply spool, and a second DC motor that rotates the wind-up spool, and the controller may calculate the rotation velocity of the first DC motor by driving the first DC motor to rotate in the same direction as a rotation direction for transporting the film-shaped medium from the supply spool side to the wind-up spool side, sag the film-shaped medium by driving the second DC motor to rotate in a direction opposite to the rotation direction for transporting the film-shaped medium from the supply spool side to the wind-up spool side, while halting driving of the first DC motor, and calculate the rotation velocity of the second DC motor by driving the second motor to rotate in the same direction as the rotation direction for transporting the film-shaped medium. Alternatively, the controller may sag the film medium by driving the second motor to rotate in a direction opposite to the rotation direction for transporting the film-shaped medium from the supply spool side to the wind-up spool side, calculate the rotation velocity of the second DC motor by driving the second motor to rotate in the same direction as the rotation direction for transporting the film-shaped medium, and calculate the rotation velocity of the first DC motor by driving the first motor in the same direction as the rotation direction for transporting the film-shaped medium from the supply spool side to the wind-up spool side, while halting driving of the second motor. 
     Moreover, the apparatus is further provided with the mark detector that detects an empty mark indicative of a use limit of the film-shaped medium attached to an end portion of the film-shaped medium, in the film-shaped medium is formed a weak portion on the end side closer to the end than the position in which the empty mark is attached, the DC motor is comprised of the first DC motor that rotates the supply spool and the second DC motor that rotates the wind-up spool, and after the mark detector detects the empty mark, the controller may calculate the rotation velocity of the first DC motor by driving the first motor to rotate in the same direction as the rotation direction for transporting the film-shaped medium from the supply spool side to the wind-up spool side, drive the second motor to rotate in the same direction as the rotation direction for transporting the film-shaped medium while halting driving of the first motor to wind up the film-shaped medium with the wind-up spool, drive the first motor to rotate in a direction opposite to the rotation direction for transporting the film-shaped medium to break the film-shaped medium in the weak portion, further wind up the broken weak portion of the film-shaped medium with the wind-up spool, and calculate the rotation velocity of the second DC motor by driving the second motor to rotate in the same direction as the rotation direction for transporting the film-shaped medium, while halting driving of the first motor. 
     Advantageous Effect of the Invention 
     According to the present invention, since the rotation velocity of the DC motor is calculated by driving the DC motor without the tension due to the film-shaped medium being applied, it is possible to properly correct the supply current of the DC motor, and therefore, it is possible to obtain the effect of preventing the image quality from deteriorating. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an outside view of a printing system including a printing apparatus of an Embodiment to which the present invention is applicable; 
         FIG. 2  is a schematic configuration view of the printing apparatus of the Embodiment; 
         FIG. 3  is an explanatory view of a control state by a cam in a waiting position in which pinch rollers and film transport roller are separated from each other, and a platen roller and thermal head are separated from each other; 
         FIG. 4  is an explanatory view of a control state by the cam in a printing position in which the pinch rollers and film transport roller are brought into contact with each other, and the platen roller and thermal head are brought into contact with each other; 
         FIG. 5  is an explanatory view of a control state by the cam in a transport position in which the pinch rollers and film transport roller are brought into contact with each other, and the platen roller and thermal head are brought into contact with each other; 
         FIG. 6  is an operation explanatory view to explain the state of the waiting position in the printing apparatus; 
         FIG. 7  is an operation explanatory view to explain the state of the transport position in the printing apparatus; 
         FIG. 8  is an operation explanatory view to explain the state of the printing position in the printing apparatus; 
         FIG. 9  is an outside view showing a configuration of a first unit integrated to incorporate the film transport roller, platen roller and their peripheral parts into the printing apparatus; 
         FIG. 10  is an outside view showing a configuration of a second unit integrated to incorporate the pinch rollers and their peripheral parts into the printing apparatus; 
         FIG. 11  is an outside view of a third unit integrated to incorporate the thermal head into the printing apparatus; 
         FIG. 12  is an external perspective view showing spools of an ink ribbon cassette, coupling gear group, DC motor and encoder; 
         FIG. 13  is a block diagram illustrating a schematic configuration of a controller in the printing apparatus of this Embodiment; 
         FIG. 14  is a flowchart of a card issue routine executed by a CPU of a microcomputer of the controller in the printing apparatus of this Embodiment; 
         FIG. 15  is a flowchart of a of a DC motor correction subroutine illustrating details of DC motor correction processing of the card issue routine; 
         FIG. 16  is a flowchart of the card issue routine executed by the CPU of the microcomputer of the controller in the printing apparatus of another Embodiment; 
         FIGS. 17A to 17E  contain explanatory views schematically illustrating a procedure for respectively measuring rotation velocities of DC motors for rotating a supply spool and a wind-up spool in this Embodiment, where  FIG. 17A  shows a state in which a sensor detects an empty mark,  FIG. 17B  shows a state of measuring a rotation velocity of a motor for rotating the supply spool with an ink ribbon sagged,  FIG. 17C  shows a state in which the sagged ink ribbon is wound up by the motor for rotating the supply spool,  FIG. 17D  shows a state in which the ink ribbon is sagged by rotating backward a motor for rotating the wind-up spool, and  FIG. 17E  shows a state of measuring a rotation velocity of the motor for rotating the wind-up spool with the ink ribbon sagged; 
         FIGS. 18A to 18E  contain explanatory views schematically illustrating a procedure for respectively measuring rotation velocities of DC motors for rotating the supply spool and the wind-up spool in another Embodiment, where  FIG. 18A  shows a state in which the sensor detects an empty mark,  FIG. 18B  shows a state of measuring the rotation velocity of the motor for rotating the supply spool with the ink ribbon sagged,  FIG. 18C  shows a state in which the sagged ink ribbon is wound up by the motor for rotating the wind-up spool,  FIG. 18D  shows a state in which a weak portion of the ink ribbon is broken by rotating backward the motor for rotating the supply spool, while rotating the motor for rotating the wind-up spool, and  FIG. 18E  shows a state of measuring the rotation velocity of the motor for rotating the wind-up spool with the ink ribbon wound up; 
         FIG. 19  is an explanatory view schematically illustrating the relationship between output and time of an encoder; and 
         FIG. 20  is an explanatory view illustrating the relationship between the number of revolutions and the supply current of each of a measurement motor and a reference motor. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     With reference to drawings, described below are Embodiments in which the present invention is applied to a printing apparatus for printing and recording text and image on a card, while performing magnetic or electric information recording on the card. 
     &lt;System Configuration&gt; 
     As shown in  FIGS. 1 and 13 , a printing apparatus  1  of this Embodiment constitutes a part of a printing system  200 . In other words, the printing system  200  is broadly comprised of a higher apparatus  201  (for example, host computer such as a personal computer), and the printing apparatus  1 . 
     The printing apparatus  1  is connected to the higher apparatus  201  via an interface with the figure omitted, and the higher apparatus  201  is capable of transmitting image data, magnetic or electric recording data and the like to the printing apparatus  1  to indicate recording operation and the like. In addition, the printing apparatus  1  has an operation panel section (operation display section)  5  (see  FIG. 13 ), and as well as recording operation indication from the higher apparatus  201 , recording operation is also capable of being indicated from the operation panel section  5 . 
     The higher apparatus  201  is connected to an image input apparatus  204  such as a digital camera and scanner, an input apparatus  203  such as a keyboard and mouse to input commands and data to the higher apparatus  201 , and a monitor  202  such as a liquid crystal display to display data and the like generated in the higher apparatus  201 . 
     &lt;Printing Apparatus&gt; 
     As shown in  FIG. 2 , the printing apparatus  1  has a housing  2 , and in the housing  2  are provided an information recording section A, printing section B, media storage section C, storage section D and rotating unit F. 
     (Information Recording Section) 
     The information recording section A is comprised of a magnetic recording section  24 , non-contact type IC recording section  23 , and contact type IC recording section  27 . 
     (Media Storage Section) 
     The media storage section C aligns and stores a plurality of cards in a standing posture, is provided at its front end with a separation opening  7 , and feeds and supplies sequentially starting with the card in the front row with a pickup roller  19 . 
     (Rotating Unit) 
     The fed blank card Ca is first sent to a reverse unit F with carry-in rollers  22 . The reverse unit F is comprised of a rotating frame  80  bearing-supported by the housing  2  to be turnable, and two roller pairs  20 ,  21  supported on the frame. Then, the roller pairs  20 ,  21  are axially supported by the rotating frame  80  to be rotatable. 
     In the outer region of the rotating reverse unit F are disposed the above-mentioned magnetic recording section  24 , non-contact type IC recording section  23 , and contact type IC recording section  27 . Then, the roller pairs  20 ,  21  form a medium transport path  65  for transporting the card Ca toward one of the information recording sections  23 ,  24  and  27 , and data is magnetically or electrically written on the card Ca in the recording sections. 
     (Printing Section) 
     The printing section B is to form an image such as a photograph of face and text data on the frontside and backside of the card Ca, and a medium transport path P 1  for carrying the card Ca is provided on an extension of the medium transport path  65 . Further, in the medium transport path P 1  are disposed transport rollers  29 ,  30  that transport the card Ca, and the rollers are coupled to a transport motor not shown. 
     The printing section B has a film-shaped medium transport mechanism, and is provided with an image formation section B 1  that forms an image, with a thermal head  40 , on a transfer film  46  transported with the transport mechanism, and a transfer section B 2  that subsequently transfers the image formed on the transfer film  46  to the surface of the card Ca on the medium transport path P 1  with a heat roller  33 . 
     On the downstream side of the printing section B is provided a medium transport path P 2  for carrying the printed card Ca to a storage stacker  60 . In the medium transport path P 2  are disposed transport rollers  37 ,  38  that transport the card Ca, and the rollers are coupled to a transport motor not shown. 
     A decurl mechanism  36  is disposed in between the transport roller  37  and the transport roller  38 , presses the card center portion held between the transport rollers  37 ,  38 , and thereby corrects curl generated by thermal transfer with the heat roller  33 . Therefore, the decurl mechanism  36  is configured to be able to shift to positions in the vertical direction as viewed in  FIG. 2  by an up-and-down mechanism including a cam not shown. 
     (Storage Section) 
     The storage section D is configured to store cards Ca sent from the printing section B in the storage stacker  60 . The storage stacker  60  is configured to shift downward in  FIG. 2  with an up-and-down mechanism  61 . 
     (Details of the Printing Section) 
     Next, the printing section B in the entire configuration of the above-mentioned printing apparatus  1  will be further described specifically. 
     The transfer film  46  has the shape of a band having a width slightly larger than the width direction of the card Ca, and is formed by layering, from above, an ink reception layer that receives ink of an ink ribbon  41 , a transparent protective layer that protects the surface of the ink reception layer, a peeling layer to promote integral peeling of the ink reception layer and protective layer by heat, and a substrate (base film) in this order. 
     The transfer film  46  is wound up or fed by a wind-up roll or feed roll that rotates inside a transfer film cassette by driving of motor Mr 2  or M 4 , respectively. In other words, in the transfer film cassette, a wind-up spool  47  is disposed in the center of the wind-up roll, a feed spool  48  is disposed in the center of the feed roll, a rotation drive force of the motor Mr 2  is transferred to the wind-up spool  47  via a gear not shown, and a rotation derive force of the motor Mr 4  is transferred to the feed spool  48  via a gear not shown. A film transport roller  49  is a main drive roller to carry the transfer film  46 , and by controlling drive of the roller  49 , transport amount and transport halt position of the transfer film  46  are determined. The film transport roller  49  is coupled to a stepping motor not shown. The motors Mr 2  and Mr 4  are driven also in driving the film transport roller  49 , are to wind the transfer film fed from one of the wind-up spool  47  and feed spool  48  by the other one, and are not driven as main transport of the transfer film  46 . In addition, forward-backward rotatable DC motors are used for the motors Mr 2  and Mr 4 . 
     Pinch rollers  32   a  and  32   b  are disposed on the periphery of the film transport roller  49 . Although not shown in  FIG. 2 , the pinch rollers  32   a  and  32   b  are configured to be movable to move and retract with respect to the film transport roller  49 , and in a state in the figure, the rollers move to the film transport roller  49  to come into press-contact, and thereby wind the transfer film  46  around the film transport roller  49 . By this means, the transfer film  46  undergoes accurate transport by a distance corresponding to the number of revolutions of the film transport roller  49 . 
     The ink ribbon  41  is stored in an ink ribbon cassette  42  in a state in which the ribbon is laid between a supply spool  43  for supplying the ink ribbon  41  and wind-up spool  44  for winding up the ink ribbon  41 , the wind-up spool  44  rotates by a drive force of a motor Mr 1 , and the supply spool  43  rotates by a drive force of a motor Mr 3 . 
     Forward-backward rotatable DC motors are used for the motors Mr 1  and Mr 3 . Further, between the motors Mr 1  and Mr 3  is disposed a temperature sensor Th such as a thermistor that measures ambient temperatures of the motors Mr 1  and Mr 3 . 
     The ink ribbon  41  is configured by repeating color ribbon panels of Y (Yellow), M (Magenta), and C (Cyan) and a Bk (Black) ribbon panel in the longitudinal direction in a face sequential manner. Further, an empty mark indicative of a use limit of the ink ribbon  41  is attached to an end portion of the ink ribbon  41 . “Se 2 ” shown in  FIG. 2  denotes a transmission sensor to detect the empty mark. In addition, in this Embodiment, the empty mark is comprised of a single or a plurality of black straight lines continued from one side to the other side in the width direction of the ink ribbon  41 , but the present invention is not limited thereto. 
     A platen roller  45  and thermal head  40  form the image formation section B 1 , and the thermal head  40  is disposed in a position opposed to the platen roller  45 . The thermal head  40  has a plurality of heating elements lined in the main scanning direction, these heating elements are selectively heated and controlled by a head control IC (not shown) according to printing data, and an image is printed on the transfer film  46  via the ink ribbon  41 . In addition, a cooling fan  39  is to cool the thermal head  40 . 
     The ink ribbon  41  with which printing on the transfer film  46  is finished is peeled off from the transfer film  46  with a peeling roller  25  and peeling member  28 . The peeling member  28  is fixed to the ink ribbon cassette  42 , the peeling roller  25  comes into contact with the peeling member  28  in printing, and the roller  25  and member  28  nip the transfer film  46  and ink ribbon  41  to peel. Then, the peeled ink ribbon  41  is wound around the wind-up spool  44  by the drive force of the motor Mr 1 , and the transfer film  46  is transported to the transfer section B 2  having the platen roller  31  and heat roller  33  by the film transport roller  49 . 
     In the transfer section B 2 , the transfer film  46  is nipped together with the card Ca by the heat roller  33  and platen roller  31 , and the image on the transfer film  46  is transferred to the card surface. In addition, the heat roller  33  is attached to an up-and-down mechanism (not shown) so as to come into contact with and separate from the platen roller  31  via the transfer film  46 . 
     The configuration of the image formation section B 1  will specifically be described further together with its action. As shown in  FIGS. 3 to 5 , the pinch rollers  32   a ,  32   b  are respectively supported by an upper end portion and lower end portion of a pinch roller support member  57 , and the pinch roller support member  57  is supported rotatably by a support shaft  58  penetrating the center portion of the member  57 . As shown in  FIG. 10 , the support shaft  58  is laid at its opposite end portions between long holes  76 ,  77  formed in the pinch roller support member  57 , and is at its center portion fixed to a fix portion  78  of a bracket  50 . Further, the long holes  76 ,  77  are provided with spaces in the horizontal direction and vertical direction with respect to the support shaft  58 . By this means, it is made possible to adjust the pinch rollers  32   a ,  32   b  with respect to the film transport roller  49 , described later. 
     Spring members  51  ( 51   a ,  51   b ) are mounted on the support shaft  58 , and end portions on which the pinch rollers  32   a ,  32   b  are installed of the pinch roller support member  57  respectively contact the spring members  51 , and are biased to the direction of the film transport roller  49  by the spring forces. 
     The bracket  50  comes into contact with the cam operation surface of a cam  53  in a cam receiver  81 , and is configured to shift in the horizontal direction viewed in the figure with respect to the film transport roller  49 , corresponding to rotation in the arrow direction of the cam  53  with a cam shaft  82  as the axis rotating by drive force of a drive motor  54  (see  FIG. 10 ). Accordingly, when the bracket  50  moves toward the film transport roller  49  ( FIGS. 4 and 5 ), the pinch rollers  32   a ,  32   b  come into press-contact with the film transport roller  49  against the spring members  51  with the transfer film  46  nipped, and wind the transfer film  46  around the film transport roller  49 . 
     At this point, the pinch roller  32   b  in a farther position from a shaft  95  as a rotation axis of the bracket  50  first comes into press-contact with the film transport roller  49 , and next, the pinch roller  32   a  comes into press-contact. In this way, by arranging the shaft  95  that is the rotation axis higher than the film transport roller  49 , the pinch roller support member  57  comes into contact with the film transport roller  49  while rotating, instead of parallel shift, and there is the advantage that the space in the width direction is less than in the parallel shift. 
     Further, the press-contact forces when the pinch rollers  32   a ,  32   b  come into press-contact with the film transport roller  49  are uniform in the width direction of the transfer film  46  by the spring members  51 . At this point, since the long holes  76 ,  77  are formed on the opposite sides of the pinch roller support member  57  and the support shaft  58  is fixed to the fix portion  78 , it is possible to adjust the pinch roller support member  57  in three directions, and the transfer film  46  is transported in a correct posture by rotation of the film transport roller  49  without causing skew. In addition, adjustments in three directions described herein are to (i) adjust the parallel degree in the horizontal direction of the shafts of the pinch rollers  32   a ,  32   b  with respect to the shaft of the film transport roller  49  to uniform the press-contact forces in the shaft direction of the pinch rollers  32   a ,  32   b  with respect to the film transport roller  49 , (ii) adjust shift distances of the pinch rollers  32   a ,  32   b  with respect to the film transport roller  49  to uniform the press-contact force of the pinch roller  32   a  on the film transport roller  49  and the press-contact force of the pinch roller  32   b  on the film transport roller  49 , and (iii) adjust the parallel degree in the vertical direction of the shafts of the pinch rollers  32   a ,  32   b  with respect to the shaft of the film transport roller  49  so that the shafts of the pinch rollers  32   a ,  32   b  are perpendicular to the film travel direction. 
     Furthermore, the bracket  50  is provided with a tension receiving member  52  that comes into contact with a portion of the transfer film  46  which is not wound around the film transport roller  49  when the bracket  50  moves toward the film transport roller  49 . 
     The tension receiving member  52  is provided to prevent the pinch rollers  32   a ,  32   b  from retracting from the film transport roller  49  respectively against the biasing forces of the spring members  51  due to the tension of the transfer film  46  occurring when the pinch rollers  32   a ,  32   b  bring the transfer film  46  into press-contact with the film transport roller  49 . Accordingly, the tension receiving member  52  is attached to the front end of the end portion on the rotation side of the bracket  50  so as to come into contact with the transfer film  46  in the position to the left of the pinch rollers  32   a ,  32   b  viewed in the figure.  FIG. 2  shows a state in which the tension receiving member  52  is brought into contact with the transfer film  46 . 
     By this means, the cam  53  is capable of directly receiving the tension occurring due to elasticity of the transfer film  46  through the tension receiving member  52 . Accordingly, the pinch rollers  32   a ,  32   b  are prevented from retracting from the film transport roller  49  due to the tension and from decreasing the press-contact forces of the pinch rollers  32   a ,  32   b , thereby maintain the winding state in which the transfer film  46  is brought into intimate contact with the film transport roller  49 , and are able to perform accurate transport. 
     As shown in  FIG. 9 , the platen roller  45  disposed along the transverse width direction of the transfer film  46  is supported by a pair of platen support members  72  rotatable on a shaft  71  as the axis. The pair of platen support members  72  support opposite ends of the platen roller  45 . The platen support members  72  are respectively connected to end portions of a bracket  50 A having the shaft  71  as a common rotating shaft via spring members  99 . 
     The bracket  50 A has a substrate  87 , and cam receiver support portion  85  formed by bending the substrate  87  in the direction of the platen support member  72 , and the cam receiver support portion  85  holds a cam receiver  84 . A cam  53 A rotating on a cam shaft  83  as the axis driven by the drive motor  54  is disposed between the substrate  87  and the cam receiver support portion  85 , and is configured so that the cam operation surface and cam receiver  84  come into contact with each other. Accordingly, when the bracket  50 A moves in the direction of the thermal head  40  by rotation of the cam  53 A, the platen support members  72  also shift to bring the platen roller  45  into press-contact with the thermal head  40 . 
     The spring members  99  and cam  53 A are thus disposed vertically between the bracket  50 A and platen support members  72 , and it is thereby possible to store a platen shift unit within the distance between the bracket  50 A and platen support members  72 . Further, the width direction is held within the width of the platen roller  45 , and it is possible to save space. 
     Moreover, since the cam receiver support portion  85  is fitted into bore portions  72   a ,  72   b  (see  FIG. 9 ) formed in the platen support members  72 , even when the cam receiver support portion  85  is formed while protruding in the direction of the platen support members  72 , the distance between the bracket  50 A and the platen support members  72  is not increased, and also in this respect, it is possible to save space. 
     When the platen roller  45  comes into press-contact with the thermal head  40 , the spring members  99  connected to respective platen support members  72  act each so as to uniform the press-contact force on the width direction of the transfer film  46 . Therefore, when the transfer film  46  is transported by the film transport roller  49 , the skew is prevented, and it is possible to perform image formation on the transfer film  46  by the thermal head  40  accurately without the printing region of the transfer film  46  shifting in the width direction. 
     The substrate  87  of the bracket  50 A is provided with a pair of peeling roller support members  88  for supporting opposite ends of the peeling roller  25  via spring members  97 , and when the bracket  50 A moves to the thermal head  40  by rotation of the cam  53 A, the peeling roller  25  comes into contact with the peeling member  28  to peel off the transfer film  46  and ink ribbon  41  nipped between the roller and member. The peeling roller support members  88  are also provided respectively at opposite ends of the peeling roller  25  as in the platen support members  72 , and are configured so as to uniform the press-contact force in the width direction on the peeling member  28 . 
     A tension receiving member  52 A is provided in an end portion on the side opposite to the end portion on the shaft support  59  side of the bracket  50 A. The tension receiving member  52 A is provided to absorb the tension of the transfer film  46  occurring in bringing the platen roller  45  and peeling roller  25  respectively into press-contact with the thermal head  40  and peeling member  28 . The spring members  99  and  97  are provided so as to uniform the press-contact force on the width direction of the transfer film  46 , and in order for the spring members  99  and  97  not to be inversely behind the tension of the transfer film  46  and decrease the press-contact force on the transfer film  46 , the tension receiving member  52 A receives the tension from the transfer film  46 . In addition, since the tension receiving member  52 A is also fixed to the bracket  50 A as in the above-mentioned tension receiving member  52 , the cam  53 A receives the tension of the transfer film  46  via the bracket  50 A, and is not behind the tension of the transfer film  46 . By this means, the press-contact force of the thermal head  40  and platen roller  45  and the press-contact force of the peeling member  28  and peeling roller  25  are held, and it is thereby possible to perform excellent printing and peeling. Further, any error does not occur in the transport amount of the transfer film  46  in driving the film transport roller  49 , the transfer film  46  corresponding to the length of the printing region is accurately transported to the thermal head  40 , and it is possible to perform printing with accuracy. 
     The cam  53  and cam  53 A are driven by same drive motor  54  with a belt  98  (see  FIG. 3 ) laid therebetween. 
     When the printing section B is in a waiting position as shown in  FIG. 6 , the cam  53  and cam  53 A are in the state as shown in  FIG. 3 , the pinch rollers  32   a ,  32   b  are not brought into press-contact with the film transport roller  49 , and the platen roller  45  is not brought into press-contact with the thermal head  40  either. In other words, in the waiting position, the platen roller  45  and thermal head  40  are positioned in separate positions in which the roller  45  and head  40  are separate. 
     Then, when the cam  53  and cam  53 A are rotated in conjunction with each other and are in the state as shown in  FIG. 4 , the printing section B shifts to a printing position as shown in  FIG. 7 . At this point, the pinch rollers  32   a ,  32   b  first wind the transfer film  46  around the film transport roller  49 , and concurrently, the tension receiving member  52  comes into contact with the transfer film  46 . Subsequently, the platen roller  45  comes into press-contact with the thermal head  40 . In this printing position, the platen roller  45  shifts toward the thermal head  40  to nip the transfer film  46  and ink ribbon  41  and come into press-contact, and the peeling roller  25  is in contact with the peeling member  28 . 
     In this state, when transport of the transfer film  46  is started by rotation of the film transport roller  49 , at the same time, the ink ribbon  41  is also wound around the wind-up spool  44  by operation of the motor Mr 1  and transported in the same direction. During this transport, a positioning mark provided in the transfer film  46  passes through a sensor Se 1  and shifts a predetermined amount, and at the time the transfer film  46  arrives at a printing start position, printing by the thermal head  40  is performed on the predetermined region of the transfer film  46 . Particularly, since the tension of the transfer film  46  is large during printing, the tension of the transfer film  46  acts on the direction for separating the pinch rollers  32   a ,  32   b  from the film transport roller  49  and the direction for separating the peeling roller  25  and platen roller  45  from the peeling member  28  and thermal head  40 . However, as described above, since the tension of the transfer film  46  is received in the tension receiving members  52 ,  52 A, the press-contact forces of the pinch rollers  32   a ,  32   b  are not decreased, it is thereby possible to perform accurate film transport, the press-contact force of the thermal head  40  and platen roller  45  and the press-contract force of the peeling member  28  and peeling roller  25  are not decreased either, and it is thereby possible to perform accurate printing and peeling. The ink ribbon  41  with which printing is finished is peeled off from the transfer film  46  and wound around the wind-up spool  44 . 
     A shift amount by transport of the transfer film  46  i.e. a length in the transport direction of a printing region to undergo printing is detected by an encoder (not shown) provided in the film transport roller  49 , rotation of the film transport roller  49  is halted corresponding to detection, and at the same time, winding by the wind-up spool  44  by operation of the motor Mr 1  is also halted. By this means, finished is printing with the ink of the first ink panel on the printing region of the transfer film  46 . 
     Next, when the cam  53  and cam  53 A are further rotated in conjunction with each other and are in the state as shown in  FIG. 5 , the printing section B shifts to a transport position as shown in  FIG. 8 , and the platen roller  45  returns to the direction of retracting from the thermal head  40 . In this state, the pinch rollers  32   a ,  32   b  still wind the transfer film  46  around the film transport roller  49 , the tension receiving member  52  is in contact with the transfer film  46 , and the transfer film  46  is transported backward to an initial position by rotation in the backward direction of the film transport roller  49 . Also at this point, the shift amount of the transfer film  46  is controlled by rotation of the film transport roller  49 , and the transfer film  46  is transported backward corresponding to the length in the transport direction of the printing region subjected to printing. In addition, the ink ribbon  41  is also rewound a predetermined amount with the motor Mr 3 , and the ink panel of the ink to print next waits in the initial position (feeding position). 
     Then, the control state by the cam  53  and cam  53 A becomes the state as shown in  FIG. 4  again and the printing position as shown in  FIG. 7 , the platen roller  45  is brought into press-contact with the thermal head  40 , the film transport roller  49  rotates in the forward direction again to shift the transfer film  46  corresponding to the length of the printing region, and printing with the ink of the next ink panel is performed with the thermal head  40 . 
     Thus, the operation in the printing position and transport position is repeated until printing with ink of all or predetermined ink panel is finished. Then, when printing with the thermal head  40  is finished, the image-formed region of the transfer film  46  is transported to the heat roller  33 , and at this point, the cam  53  and cam  53 A shift to the state as shown in  FIG. 3 , and release press-contact with the transfer film  46 . Subsequently, transfer to the card Ca is performed while transporting the transfer film  46  by driving of the wind-up spool  47 . 
     Such a printing section B is divided into three units  90 ,  91 , and  92 . 
     As shown in  FIG. 9 , in the first unit  90 , a unit frame body  75  is installed with a drive shaft  70  that rotates by driving of the motor  54  (see  FIG. 10 ), and the drive shaft  70  is inserted in the film transport roller  49 . Below the film transfer film  49  are disposed the bracket  50 A and a pair of platen support members  72 , and these members are supported rotatably by the shaft  71  laid between opposite side plates of the unit frame body  75 . 
     In  FIG. 9 , a pair of cam receiver support portions  85  that are a part of the bracket  50 A appear from the bore portions  72   a ,  72   b  formed in the platen support members  72 . The cam receiver support portions  85  hold a pair of cam receivers  84  disposed at the back thereof. Then, at the back of the cam receivers  84  is disposed the cam  53 A installed in the cam shaft  83  inserted in the unit frame body  75 . The cam shaft  83  is laid between opposite side plates of the unit frame body  75 . 
     The above-mentioned thermal head  40  is disposed in the position opposed to the platen roller  45  with a transport path of the transfer film  46  and ink ribbon  41  therebetween. The thermal head  40 , members related to heating and cooling fan  39  are integrated into the third unit  92  as shown in  FIG. 11 , and are disposed opposite the first unit  90 . 
     The first unit  90  collectively holds the platen roller  45 , peeling roller  25  and tension receiving member  52 A varying in position by printing operation in the movable bracket  50 A, and thereby eliminates the need of position adjustments among the members. Moreover, by shifting the bracket  50 A by rotation of the cam  53 , it is possible to shift the members to predetermined positions. Further, since the bracket  50 A is provided, it is possible to store in the same unit as that of the fixed film transport roller  49 , the transport drive portion by the film transport roller  49  required to transport the transfer film with accuracy and the transfer position regulation portion by the platen roller  45  are included in the same unit, and therefore, the need is eliminated for position adjustments between both portions. 
     As shown in  FIG. 10 , in the second unit  91 , the cam shaft  82  installed with the cam  53  is inserted in a unit frame body  55 , and is coupled to an output shaft of the drive motor  54 . Then, the second unit  91  supports the bracket  50  in the unit frame body  55  movably to come into contact with the cam.  53 , and to the bracket  50  are fixed the support shaft  58  that supports the pinch roller support member  57  rotatably and the tension receiving member  52 . 
     In the pinch roller support member  57 , the spring members  51   a ,  51   b  are attached to the support shaft  58 , and their end portions are respectively brought into contact with the opposite ends of the pinch roller support member  57  that supports the pinch rollers  32   a ,  32   b  to bias to the direction of the film transport roller  49 . In the pinch roller support member  57 , the support shaft  58  is inserted in the long holes  76 ,  77 , and is fixed and supported in the center portion by the bracket  50 . 
     A spring  89  for biasing the pinch roller support member  57  toward the bracket  50  is provided between the bracket  50  and the pinch roller support member  57 . By this spring  89 , the pinch roller support member  57  is biased in the direction of moving backward from the film transport roller  49  of the first unit  90 , and therefore, it is possible to easily pass the transfer film  46  through between the first unit  90  and the second unit  91  in setting the transfer film cassette in the printing apparatus  1 . 
     The second unit  91  holds the pinch rollers  32   a ,  32   b , and tension receiving member  52  varying in position corresponding to printing operation in the bracket  50 A, shifts the pinch rollers  32   a ,  32   b  and tension receiving member  52  by shifting the bracket  50 A by rotation of the cam  53 , and thereby simplifies position adjustments between the rollers and member, and position adjustments between the pinch rollers  32   a ,  32   b  and the film transport roller  49 . Such a second unit  91  is disposed opposite the first unit  90  with the transfer film  46  therebetween. 
     By thus making the units, it is also possible to pull each of the first unit  90 , second unit  92  and third unit  93  out of the main body of the printing apparatus  1  as in the cassette of each of the transfer film  46  and ink ribbon  41 . Accordingly, in replacing the cassette due to consumption of the transfer film  46  or ink ribbon  41 , when the units  90 ,  91  and  92  are pulled out as required, it is possible to install the transfer film  46  or ink ribbon  41  readily inside the apparatus in inserting the cassette. 
     As described above, by combining the first unit  90  into which are integrated the platen roller  45 , bracket  50 A, cam  53 A, and platen support member  72 , and the second unit  91  into which are integrated the pinch rollers  32   a ,  32   b , bracket  50 , cam  53  and spring members  51 , and placing and installing the third unit  92  with the thermal head  40  attached thereto opposite the platen roller  45 , it is possible to perform assembly in manufacturing the printing apparatus and adjustments in maintenance with ease and accuracy. Moreover, by integrating, it is possible to perform removal from the apparatus with ease, and the handleability as the printing apparatus is improved. 
     &lt;Relationship Between Spool and Motor&gt; 
     Described next is the relationship between the spools  43 ,  44  and motors Mr 3  and Mr 1  of the ink ribbon cassette  42 . 
     As shown in  FIG. 12 , a gear fitted into the motor shaft is fitted into one side of the motor shaft of the motor Mr 3 , and a gear with a diameter slightly larger than that of the supply spool  43  is fitted into the rotating shaft of the supply spool  43 . The gear fitted into the motor shaft of the motor Mr 3  and the gear fitted into the rotating shaft of the supply spool  43  are. coupled with a coupling gear group  8  comprised of a plurality of gears respectively meshing with these gears. Accordingly, by rotating the motor Mr 3  forward and backward, the supply spool  43  also rotates forward and backward. 
     On the other hand, a rotating plate  11  with a plurality of (“8” in this Example) slits (openings) formed at regular intervals is fitted into the other side of the motor shaft of the motor Mr 3 , and a transmission sensor  13  is disposed corresponding to the positions of the slits. The rotating plate  11  and transmission sensor  13  constitute the encoder  15 . Accordingly, by the rotating plate  11  rotating by driving of the motor Mr 3 , the transmission sensor  13  constituting the encoder  15  outputs signals of ON and OFF (also see  FIG. 19 ). 
     The relationship between the wind-up spool  44  and the motor Mr 1  is the same as the above-mentioned relationship between the supply spool  43  and the motor Mr 3 , and reference numerals of corresponding members are assigned inside the bracket in  FIG. 12  to omit descriptions thereof. 
     Described next is control and electric system of the printing apparatus  1 . As shown in  FIG. 13 , the printing apparatus  1  has a controller  100  that performs operation control of the entire printing apparatus  1 , and a power supply section  120  that transforms utility AC power supply into DC power supply that enables each mechanism section, controller and the like to be driven and actuated. 
     &lt;Controller&gt; 
     As shown in  FIG. 13 , the controller  100  is provided with a microcomputer  102  that performs entire control processing of the printing apparatus  1 . The microcomputer  102  is comprised of a CPU that operates at fast clock as the central processing unit, ROM in which are stored programs of the printing apparatus  1  and program data related to the reference motor described later and the like, RAM that works as a work area of the CPU, and internal buses that connect the components. 
     The microcomputer  102  is connected to an external bus. The external bus is connected to an interface, not shown, to communicate with the higher apparatus  201 , and buffer memory  101  to temporarily store printing data to print on the card Ca, recording data to magnetically or electrically record in a magnetic stripe or stored IC of the card Ca, and the like. 
     Further, the external bus is connected to a sensor control section  103  that controls signals from various sensors, an actuator control section  104  including motor drivers and the like for supplying drive pulses and drive power to respective motors, a thermal head control section  105  to control thermal energy to heating elements constituting the thermal head  40 , an operation display control section  106  to control the operation panel section  5 , a nonvolatile memory  107  such as EEPROM and flash memory, and the above-mentioned information recording section A. 
     Herein, a motor driver (not shown) which constitutes a part of the actuator control section  104  and supplies drive power to the motors Mr 1  and Mr 3  will be described briefly. In this Embodiment, the motor driver is configured by having a timer IC that generates a pulse train to enable duty (supply current) to be changed. Such duty is given as data from the microcomputer  102  side. In addition, in assuming that a period of a switching frequency is T and that current passage time is t, the duty is expressed by {(T−t/T)}×100(%). Therefore, the motors Mr 1  and Mr 3  are driven by PWM (Pulse Width Modulation) pulses generated in the timer IC according to the duty indicated by the CPU of the microcomputer  102 . In addition, in order to suppress noise while enhancing energy efficiency, flywheel diodes (not shown) are parallel connected to the motors Mr 1  and Mr 3 , respectively. 
     The power supply section  120  supplies operation/drive power to the controller  100 , thermal head  40 , heat roller  33 , operation panel section  5 , information recording section A and the like. 
     &lt;Operation&gt; 
     Next, referring to a flowchart, card issue operation by the printing apparatus  1  according to this Embodiment will be described with particular emphasis on the CPU (hereinafter, simply referred to as CPU) of the microcomputer  102 . In addition, the description will be given while assuming that each of members constituting the printing apparatus  1  is positioned in a home (initial) position (for example, state as shown in  FIG. 2 ), and that initial setting processing for expanding programs and program data stored in the ROM in the RAM is already finished. Further, the operation of the printing section B (image formation section B 1 , transfer section B 2 ) is already described, and therefore, in order to omit redundancy, the description will be given simply. 
     As shown in  FIG. 14 , in a card issue routine, in step  320 , printing data and the like is received from the higher apparatus  201 . In other words, the CPU receives the printing data (printing data of Bk, color component printing data of Y, M, C) for one surface (for example, frontside) and the other surface (for example, backside) and the magnetic or electric recording data from the higher apparatus  201  to store in the buffer memory  101 . 
     In next step  322 , the CPU performs first transfer processing to form an image (mirror image) on the transfer film  46  in the image formation section B 1 . In other words, by controlling the thermal head  40  of the image formation section B 1  according to the color component printing data of Y, M, C and printing data of Bk stored in the buffer memory  101 , the section B 1  forms an image with Y, M, C and Bk ink of the ink ribbon  41  on the transfer film  46 . The CPU outputs the printing data for each line to the thermal head  40  side via the thermal head control section  105 , and thereby selectively heats the heating elements lined in the main scanning direction to drive the thermal head  40 . In addition, in this Embodiment, after forming the image of the one surface side in the region of the transfer film  46 , an image of the other surface side is formed in the next region of the transfer film  46 . 
     In parallel with the first transfer processing in step  322 , the CPU feeds the card Ca out of the media storage section C, performs recording processing on the card Ca based on the magnetic or electric recording data, in one of the magnetic recording section  24 , non-contact type IC recording section  23  and contact type IC recording section  27  constituting the information recording section A, and then, transports the card Ca to the transfer section B 2 . 
     In next step  324 , the CPU performs second transfer processing to transfer the image formed on the transfer film  46  to the card Ca in the transfer section B 2 . In the second transfer processing, the CPU controls so that the card Ca and the image formed in the region of the transfer film  46  arrive at the transfer section B 2  in synchronization with each other. In addition after transferring the image to one surface of the card Ca, the CPU transports the card Ca to the rotating unit F side to rotate the card Ca 180°, and transfers the image for the other surface to the other surface of the card Ca. 
     Next, in step  326 , the CPU determines whether or not the sensor Se 2  detects the empty mark attached to the end portion of the ink ribbon  41 , and in a negative determination, finishes the card issue routine. In a positive determination, the CPU executes DC motor correction processing in next step  328 , and finishes the card issue routine. In addition, in parallel with steps  326  and  328 , the CPU corrects curl of the card Ca occurring by thermal transfer by the heat roller  33  with the decurl mechanism  36 , and then, discharges the card Ca toward the storage stocker  60 . 
     (DC Motor Correction) 
     Details of the DC motor correction processing in step  328  in  FIG. 14  will be described next with reference to  FIG. 15 , and further, before the details, the overview of the DC motor correction processing will be described. 
     As shown in  FIGS. 17A to 17E , after the sensor Se 2  detects the empty mark attached to the end portion of the ink ribbon  41  (see  FIG. 17A ), the CPU drives the motor Mr 3  to rotate forward while halting the motor Mr 1  so as to sag the ink ribbon  41  (see  FIG. 17B ). For the motors Mr 1  and Mr 3 , the forward rotation is set for the rotation direction (i.e. rotation direction for the direction in which the ink ribbon  41  is transported in the printing processing) in transporting the ink ribbon  41  from the supply spool  43  side to the wind-up spool  44  side, and the backward rotation is set for the opposite direction. The reason for making such setting is that the DC motor generates a difference in the rotation velocity by the rotation direction. When the motor Mr 3  rotates forward, the rotation is the same direction as in image formation operation in the image formation section B 1 , and therefore, the CPU retrieves a rotation amount of the Mr 3  detected in the encoder  15 . 
     Next, to cancel the sag of the ink ribbon  41 , the CPU drives the motor Mr 3  to rotate backward while halting the motor Mr 1  (see  FIG. 17C ), and then, to sag the ink ribbon  41 , drives the motor Mr 1  to rotate backward while halting the motor Mr 3  (see  FIG. 17D ). When the motor Mr 1  rotates backward, since the direction is opposite to the direction in image formation operation in the image formation section B 1 , the CPU does not retrieve the rotation amount of the motor Mr 1  detected in the encoder  16  (see  FIG. 12 ). Then, the CPU drives the motor Mr 1  to rotate forward while halting the motor Mr 3  (see  FIG. 17E ). When the motor Mr 1  rotates forward, since the direction is the same as in image formation operation in the image formation section B 1 , the CPU retrieves the rotation amount of the motor Mr 1  detected in the encoder  16 . 
     In addition, the state of  FIG. 17B  may shift to the state of  FIG. 17E  by skipping states of  FIGS. 17C and 17D , but there is the risk that an error occurs in detecting the rotation amount of the motor Mr 1  by a slide load and winding fluctuations of the ink ribbon  41 , and therefore, in this Embodiment, the rotation amount of the motor Mr 1  is detected in  FIG. 17E  via  FIGS. 17C and 17D . 
     Using the above-mentioned description as a premise, details of the DC motor correction processing will be described. As shown in  FIG. 15 , in a DC motor correction processing subroutine, in step  332 , the CPU determines whether or not a measurement target for the rotation amount is Mr 1 . In the example of  FIGS. 17A to 17E  as described above, since the rotation amount of the motor Mr 3  is first measured before the motor Mr 1  (see  FIG. 17B ), the determination in step  332  is negative, and the motor Mr 3  is the measurement target. 
     Next in step  336 , the CPU measures the rotation amount of the motor Mr 3  to calculate the rotation velocity. In other words, in this Embodiment, as shown in  FIG. 12 , eight slits are formed in the rotating plate  11 , and as shown in  FIG. 19 , the CPU counts eight (ON, OFF) signals output from the encoder  15  when the rotating plate  11  rotates once, and measures the rotation amount of the motor Mr 3  from the time (the time the rotating plate  11  rotates corresponding to eight clocks) corresponding to the count. In other words, the CPU calculates the rotation velocity of the motor Mr 3  from the time (time from of time t 0  to time t 1 ) corresponding to the time taken for the encoder  15  to detect that the motor Mr 3  rotates once. Since rotation of the motors Mr 1  and Mr 3  initially receives the effect by the inertia of the ink ribbon  41  wound around the spools, as shown in  FIG. 19 , output from the encoder  15  in initial rotation is not referred (discarded). In addition, this Embodiment uses the CPU having the timer function of a period of 1 ms. 
     In next step  338 , the ambient temperature of the motor Mr 3  is measured with the temperature sensor Th, and in next step  340 , the CPU applies the rotation velocity of the motor Mr 3  calculated in step  336  to a beforehand determined relationship table or relationship equation between the rotation velocity and the temperature to make a temperature correction to the rotation velocity at a predetermined temperature (for example, 25° C.). 
     Next, in step  342 , the CPU reads a reference table, and in step  344 , the CPU corrects a supply current to the motor Mr 3 . In other words, in step  342 , as shown in  FIG. 20 , the CPU reads a relationship table or relationship equation indicative of the beforehand determined relationship between the rotation velocity and the supply current in the reference motor. Further, in step  344 , the CPU applies the rotation velocity of the motor Mr 3  subjected to temperature correction in step  340  and the supply current in driving the motor Mr 3  to the relationship table or relationship equation, calculates a supply current of the motor Mr 3  for providing the same rotation velocity as the rotation velocity in driving the reference motor with the supply current with which the motor Mr 3  is driven, and stores the calculated value of the supply current of the motor Mr 3  in the nonvolatile memory  107  (see  FIG. 13 ). The reason why the calculation result is stored in the nonvolatile memory  107  is that the CPU displays a message of need of replacement of the ink ribbon cassette  42  in the operation panel section  5  in detecting the empty mark, and that the operator may thereby turn off a power supply of the printing apparatus  1  in replacing with a new ink ribbon cassette. 
       FIG. 20  shows the case where the rotation velocity (the number of revolutions N) of the motor Mr 3  is 1000 rpm, for example, the duty at this time is 25%, and the rotation velocity of the reference motor relative to this duty is 1250 rpm, and shows the example that the CPU calculates rotation (gradient) difference=(1250÷1000)=1.25, calculates the supply current (duty) as supply current=25%×1.25-31.25% to make the same rotation velocity (1250 rpm) as that of the reference motor, and increases by 6.25% (32.25%-25%). 
     Next in step  346 , as shown in  FIG. 17C , the CPU drives the motor Mr 3  to rotate backward to return the sagged ink ribbon  41  to the original position (remove the sag), and in next step  348 , determines whether or not the DC motor correction processing on the motor Mr 1  is finished. In the above-mentioned example, since the processing on the motor Mr 1  is not finished, the CPU returns to step  332 . 
     The determination in step  332  is positive. In next step  334 , as shown in  FIG. 17D , the CPU drives the motor Mr 1  to rotate backward to provide the ink ribbon  41  with the sag. Then, as in the case of the motor Mr 3 , in steps  336  to  344 , the CPU calculates a supply current of the motor Mr 1  for providing the same rotation velocity as the rotation velocity in driving the reference motor with the supply current with which the motor Mr 1  is driven forward, and stores the calculated value of the supply current of the motor Mr 1  in the nonvolatile memory  107 . Then, in step  346 , as shown in  FIG. 17E , subsequently the CPU drives the motor Mr 1  to rotate further forward to return the sagged ink ribbon  41  to the original position (remove the sag), and via a determination in step  348  (logically made a positive determination), finishes the DC motor correction subroutine. 
     In addition, the printing apparatus  1  has a transmission sensor to detect attachment and detachment of the ink ribbon cassette  42 , and by monitoring output of the transmission sensor, when the ink ribbon cassette  42  is replaced with a new ink ribbon cassette or in the above-mentioned initial setting processing, the CPU drives the motors Mr 1  and Mr 3  with the corrected supply current by adding the value of the supply current stored in the nonvolatile memory  107  to the above-mentioned timer IC as data. 
     &lt;Effects and Others&gt; 
     The effects and others of the printing apparatus  1  of this Embodiment will be described next. 
     In the printing apparatus  1  of this Embodiment, in a state in which the ink ribbon  41  is sagged i.e. in a state in which the tension of the ink ribbon  41  is not applied to the motors Mr 1  and Mr 3 , the motors Mr 1  and Mr 3  are driven forward ( FIGS. 17B and 17E ) to calculate the rotation velocities of the motors Mr 1  and Mr 3 , and it is thereby possible to properly correct supply currents of the motors Mr 1  and Mr 3 . Therefore, according to the printing apparatus  1  of this Embodiment, even when the motors Mr 1  and Mr 3  undergo age deterioration, it is possible to prevent the image quality from deteriorating. 
     Further, in the printing apparatus  1  of this Embodiment, in driving the motors Mr 1  and Mr 3  without the tension due to the ink ribbon  41  being applied, the rotation velocity is measured by driving (forward rotation) in the same direction as the rotation direction of the motors Mr 1  and Mr 3  in transporting the ink ribbon  41  from the supply spool side  43  to the wind-up spool  44  side. Accordingly, in the DC motor with a difference in the rotation velocity between forward-rotation driving and backward-rotation driving, the corrections of the motor Mn and Mr 3  are made in the rotation direction for actually transporting the ink ribbon  41 , and it is thereby possible to correct the supply currents to the motors Mr 1  and Mr 3  with accuracy. 
     Further, in the printing apparatus  1  of this Embodiment, since the corrections of the motors Mr 1  and Mr 3  are made before inserting a new ink ribbon cassette  42  after detecting the empty mark attached to the old ink ribbon  41 , it is possible to prevent dirt from adhering to a sagged new ink ribbon  41 , and prevent winding fluctuations, which occur in rewinding the once sagged new ink ribbon  41  and are the main cause of skew in transport of the ink ribbon  41 , from occurring. 
     Furthermore, the printing apparatus  1  of this Embodiment is provided with the temperature sensor Th, applies the calculated rotation velocity to the beforehand determined relationship between the rotation velocity and the temperature to make a temperature correction to the rotation velocity at a predetermined temperature, and is thereby capable of correcting the supply currents to the motor Mr 1  and Mr 3  with higher accuracy. 
     In addition, this Embodiment illustrates the printing apparatus  1  of indirect printing scheme, but the present invention is not limited thereto, and is applicable also to a printing apparatus of direct printing scheme as disclosed in Patent Document 1. Further, this Embodiment illustrates the ink ribbon  41  as a film-shaped transfer medium, but the invention is not limited thereto, and is applicable also to the transfer film  46 . In other words, when the “film-shaped medium” of claim  1  is the ink ribbon  41 , the “printing target medium” is the transfer film  46 , the “printing section” is the image formation section B 1 , the “supply spool” is the supply spool  43 , and the “wind-up spool” is the wind-up spool  44 . On the other hand, when the “film-shaped medium” of claim  1  is the transfer film  46 , the “printing target medium” is the card Ca, the “printing section” is the transfer section B 2 , the “supply spool” is the supply spool  48 , and the “wind-up spool” is the wind-up spool  47 . In other words, it is possible to make corrections of supply current similarly to the motors Mr 2  and Mr 4 . 
     Further, this Embodiment illustrates the motor Mr 3  for rotating the supply spool  43  and the motor Mr 1  for rotating the wind-up spool  44 , but the present invention is not limited thereto, and for example, is applicable to an aspect for driving the supply spool  43  and the wind-up spool  44  with a single DC motor via a plurality of gears. In such an aspect, in order to halt transfer of the rotation drive force to one of the spools, for example, a clutch mechanism such as an electromagnetic clutch may be used. 
     Furthermore, this Embodiment shows the example of calculating the rotation velocities of the motors Mr 1  and Mr 3  from the time corresponding to the time during which the encoders  15  and  16  detect that the motors Mr 1  and Mr 3  rotate a predetermined amount, respectively, (see  FIG. 19 ), but the present invention is not limited thereto, and the rotation velocities may be calculated from the rotation amounts of the motors Mr 1  and Mr 3  detected by the encoders  15  and  16  for a predetermined time, respectively. 
     Still furthermore, this Embodiment shows the example of making corrections to the motors Mr 1  and Mr 3  after detecting the empty mark attached to the ink ribbon  41 , but the present invention is not limited thereto, and for example, as shown in  FIG. 16 , the DC motor correction processing (step  328 ) may be performed for each printing (for example, before the first transfer processing in step  322 ). As the advantage of such an Embodiment, as well as being able to correct the supply current with respect to age deterioration of the motors Mr 1  and Mr 3 , since the DC motor correction processing is performed for each printing, it is possible to make a proper supply current correction corresponding to the ambient temperatures of the motors Mr 1  and Mr 3 . 
     Moreover, as shown in  FIGS. 17A to 17E , this Embodiment shows the example of measuring the rotation velocity in the order of the motor Mr 3  and motor Mr 1 , but the present invention is not limited thereto, and the rotation velocity may be measured in the order of the motor Mr 1  and motor Mr 3 . In other words, with the description given according to  FIGS. 17A to 17E , the procedure may be the order of  FIGS. 17A, 17D, 17E, 17B and 17C . More specifically, after the sensor Se 2  detects the empty mark ( FIG. 17A ), the CPU drives the motor Mr 1  to rotate backward while halting driving of the motor Mr 3  to sag the ink ribbon  41  ( FIG. 17D ), drives the motor Mr 1  to rotate forward while halting driving of the motor Mr 3  ( FIG. 17E ), calculates the rotation velocity of the motor Mr 1  to correct the supply current, drives the motor Mr 3  to rotate forward while halting driving of the motor Mr 1 , calculates the rotation velocity of the motor Mr 3  to correct the supply current ( FIG. 17B ), drives the motor Mr 3  to rotate backward while halting the motor Mr 1 , and cancels the sag of the ink ribbon ( FIG. 17C ). 
     Further, since the empty mark attached to the ink ribbon  41  indicates a use limit of the ink ribbon  41 , the ink ribbon  41  may be broken not to apply the tension of the ink ribbon  41  to the motor Mr 1 . In such an Embodiment, for example, a tear-off strip or a partially broken weak portion is formed on the end side closer to the end than the position in which the empty mark is attached in the ink ribbon  41 .  FIG. 18  shows a measurement procedure of rotation velocities of the motors Mr 1  and Mr 3  in such an Embodiment. 
     More specifically, after the sensor Se 2  detects the empty mark ( FIG. 18A ), the CPU drives the motor Mr 3  to rotate forward while halting driving of the motor Mr 1  to calculate the rotation velocity of the motor Mr 3  ( FIG. 18B ), drives the motor Mr 1  to rotate forward while halting driving of the motor Mr 3 , winds up the ink ribbon  41  with the wind-up spool  44  ( FIG. 18C ), drives the motor Mr 3  to rotate backward to break the ink ribbon  41  in the exposed weak portion, further winds up the broken end portion of the ink ribbon  41  with the wind-up spool  44  ( FIG. 18D ), drives the motor Mr 1  to rotate forward while halting driving of the motor Mr 3 , and calculates the rotation velocity of the motor Mr 1  to correct the supply current. In addition, the supply spool  43  winds up the other broken end of the ink ribbon  41  before the motor Mr 3  is halted. 
     Further, this Embodiment shows the example of forming images for one surface and the other surface in respective different regions of the transfer film  46  (step  322 ), and then, respectively transferring the images for one surface and the other surface formed on the transfer film  46  to one surface and the other surface of the card Ca (step  324 ), but the present invention is not limited thereto. An image for one surface may be formed on the transfer film  46  to transfer the formed image for one surface to one surface of the card Ca, and then, an image for the other surface may be formed on the transfer film  46  to transfer the formed image for the other surface to transfer to the other surface of the card Ca. 
     Furthermore, in this Embodiment, since the apparatus has the nonvolatile memory  107 , the CPU may store the cumulative rotation amount of the encoder  15  in the nonvolatile memory, and refer to a table or equation for beforehand determining the relationship between the cumulative rotation amount and the duty (supply current) to correct the supply currents to the motors Mr 1  and Mr 3 . 
     In addition, this Embodiment discloses the configuration in which the transport direction in the printing processing of the ink ribbon  41  and the transfer film  46  is the direction for transporting from the supply spools  43 ,  48  to the wind-up spools  44 ,  47  side, and the printing processing may be performed while winding up the ink ribbon  41  and transfer film  46  with the supply spools. In this case, the rotation direction in detecting the rotation amount of the DC motor is the rotation direction for transporting the ink ribbon  41  and transfer film  46  from the wind-up spool side to the supply spool side. In either case, it is desirable to detect the rotation amount of the DC motor while driving in the same direction as the rotation direction of the DC motor in transporting the ink ribbon  41  and transfer film  46  in the printing processing. 
     Then, as a matter of course, although this Embodiment illustrates the ink ribbon cassette  42 , the present invention is not limited thereto, and is applicable to an ink ribbon of the type that does not use a cassette. 
     [Industrial Applicability] 
     In addition, this application claims priority from Japanese Patent Application No. 2014-079572 incorporated herein by reference.