Patent Publication Number: US-6991388-B2

Title: Ink ribbon cartridge having takeup-side cover with opening positioned beneath protrusion in cover

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a Continuation-in-Part application of U.S. patent application Ser. No. 10/213,103 filed Aug. 7, 2002, now U.S. Pat. No. 6,715,946, issued Apr. 6, 2004, which is a Continuation of application Ser. No. 09/519,474 filed Mar. 6, 2000, now U.S. Pat. No. 6,623,192, issued Sep. 23, 2003, which is a Division of application Ser. No. 09/225,482 filed Jan. 6, 1999, now U.S. Pat. No. 6,257,780, issued Jul. 10, 2001, the disclosures of which are incorporated herein in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The invention relates to an ink ribbon cartridge for use in a recording device, and more specifically to an ink ribbon cartridge including an exchangeable ink ribbon having a broad width. 
     2. Description of Related Art 
     When printing is performed for forming an image on a plain paper using a thermal printer, normally an ink ribbon cartridge is used because it is easy to exchange and simple to handle. Usually, an ink ribbon cartridge includes a broad-width ink ribbon when the thermal printer is a thermal line printer. 
     In such an ink ribbon cartridge, the ink ribbon is wound around a supply tube and extends to a takeup tube. An ink layer is formed on one surface of the ink ribbon. A spool without a gear is provided at one end of each of the supply tube and the takeup tube, and a spool with a gear is provided at other end of each of the supply tube and the takeup tube. All the spools are provided with a flange. The supply tube and the takeup tube are rotated in their circumferential direction by driving force transmitted via the gears. 
     When an ink ribbon cartridge is removed from the printer or placed by itself on a table top, for example, or when an operator picks up the ink ribbon cartridge and moves it around, the ink ribbon can undesirably loosen because the spools become freely rotatable with respect to the cartridge case. 
     Japanese Patent-Application Publication (Kokai) No. HEI-8-276630 discloses a configuration for overcoming this problem. Specifically, a pair of tubular spools on which an ink ribbon is wound are rotatably supported in a cartridge case. A compression coil spring is interposed between one end of each spool and first side wall of the cartridge case. The other end of each spool is formed with a groove engageable with an protrusion formed in an opposite second side wall of the cartridge case. The configuration is provided for moving the spools toward the first side wall so the protrusions and grooves fall out of engagement when the ink ribbon cartridge is mounting in a printer. 
     On the other hand, when the ink ribbon cartridge is removed from the printer, force of the compression coil spring moves the spools in their axial directions, and the protrusions engage with the grooves, thereby preventing the spools from rotating. In this way, the ink ribbon is prevented from loosening. 
     Also, Japanese Utility-Model-application Publication (Kokai) No. HEI-6-81749 discloses another type of ink ribbon cartridge. A pair of spools on which an ink ribbon is wound are freely rotatably supported in internal of a cartridge case. A compression coil spring is interposed between one end of each spool and a first side wall of the cartridge case. A flange with a large diameter is provided to the other end of the each spool. A friction plate is adhered either an outer surface of each of the flanges an opposite second side wall of the cartridge case confronting the outer surface of each flange. 
     With this configuration also, when the ink ribbon cartridge is removed from a printer, force of the compression coil springs move the spools in their axial directions, so that the outer surface of each flange is brought into pressing contact with the second side wall of the cartridge case, thereby preventing the spools from undesirably rotating. Therefore, the ink ribbon will not loosen. 
     However, with this configuration, operations for exchanging the ink ribbon are troublesome. That is to say, when the spools with a spent ink ribbon are removed from the cartridge case, there is a danger that the compression coil springs will fall off the cartridge case. Even if the compression coil springs do not separate from the cartridge case, in order to remove the spools from the cartridge, the compression coil springs need to be once greatly compressed. 
     Further, when mounting the spools with an unused ink ribbon into the cartridge case, the spools cannot be mounted in the compression coil springs unless the compression coil springs are once greatly compressed. For these and other reasons, the existence of the compression coil springs makes operations for exchanging the ink ribbon troublesome. 
     When the spools are replaced each time a spent ink ribbon is replaced, this wastes resources and increases the costs. Therefore, the spools are removed from the supply tube and the takeup tube with the spent ink ribbon, and mounted onto new supply tube and takeup tube with a fresh ink ribbon, and then mounted back into the cartridge case. At this time, the geared spools must be set at correct ends of the supply tube and the takeup tube and at correct locations in the cartridge case, otherwise the ink ribbon will not be arranged in a correct orientation in the cartridge case. 
     SUMMARY OF THE INVENTION 
     It is conceivable to form one of the spools in a different shape than the other three spools and form one end of the tube bodies so that it will fit only the odd shaped spool. In addition, it is conceivable to form one of the spool flanges with a diameter greater than the other three spool flanges so that the odd shaped spool flange can only fit into a certain supporting hole formed to the cartridge case. With this conceivable configuration, the ink ribbon will not be mounted erroneously in the cartridge case. 
     However, even with this conceivable configurations, each time an ink ribbon is exchanged, an operator must check to find the spool with the large diameter and then find the corresponding mounting location in the cartridge case. Alternatively, the user may just keep trying to mount the ink ribbon in the cartridge case until he hits on the right flange and mounting location combination. This is troublesome and time consuming. 
     It is an objective of the invention to overcome the above-described problems and to provide a simple configuration of an ink ribbon cartridge wherein an ink ribbon can be prevented from undesirably loosening. 
     It is an another objective of the invention to provide a simple configuration of an ink ribbon cartridge wherein operations for ink ribbon replacement can be performed quickly and accurately. 
     In order to achieve the above and other objective, there is provided an ink ribbon cartridge including a case, a first spool, a second spool, a third spool, a fourth spool, a first tube, a second tube, and an ink ribbon. The case has first and second plates facing each other. The first plate is formed with first and second openings each with a cutout portion. The second plate is formed with third and fourth openings. The first and the second spools are detachably rotatably mounted in the first and second openings, respectively. The third and fourth spools have a gear and detachably rotatably mounted in the third and fourth openings, respectively. The first tube has a first end and a second end opposite from the first end. The first and second ends are detachably engaged with the first and the third spools, respectively. The second tube has a third end and a fourth end opposite from the third end. The third and fourth ends are detachably engaged with the second and fourth spools, respectively. The ink ribbon is wound around the first tube and the second tube. 
     There is also provided an ink ribbon cartridge including a case, two pairs of a right spool and a left spool each having a supporting shaft. The case has two pairs of a right side plate and a left side plate each formed with an opening with a cutout portion defined by edges. The right and left spools are detachably rotatably mounted in corresponding openings. The supporting shaft of either one of the right and left spools has a peripheral surface formed with at least one protrusion for catching on the edges defining the cutout portion. 
     There is also provided a projection extending from a cover over the takeup tube. An opening is found beneath the projection in the cover. The projection, at a minimum, adds rigidity to and facilitates mounting the ink ribbon cartridge in the printing device and the hole reduces the amount of material required for the case to reduce costs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The particular features and advantages of the invention as well as other objects will become more apparent from the following description taken in connection with the accompanying drawings, in which: 
         FIG. 1  is a cross-sectional view of a facsimile machine including an ink ribbon cartridge according to a first embodiment of the invention; 
         FIG. 2  is a plan view of the ink ribbon cartridge according to the first embodiment of the invention; 
         FIG. 3  is a partial perspective view of the ink ribbon cartridge of  FIG. 2  with a portion removed to facilitate explanation; 
         FIG. 4  is a side view in partial cross-section of a spool of the ribbon cartridge of  FIG. 2 ; 
         FIG. 5  is a side view in partial cross-section of another spool of the ink ribbon cartridge of  FIG. 2 ; 
         FIG. 6  is a side view in partial cross-section of still another spool of the ink ribbon cartridge of  FIG. 2 ; 
         FIG. 7  is a perspective view of the spools shown in  FIGS. 5 and 6 ; 
         FIG. 8(   a ) is a right side view of the ink ribbon cartridge; 
         FIG. 8(   b ) is a left side view of the ink ribbon cartridge; 
         FIG. 9(   a ) is a partial right side view of the ink ribbon cartridge in a lifted up condition; 
         FIG. 9(   b ) is an enlarged side view of a protruding rib formed in the spools; 
         FIG. 10(   a ) is a side view showing a support opening and a support portion of an ink ribbon cartridge according to a second embodiment of the invention; 
         FIG. 10(   b ) is a side view showing the support opening and the support portion of  FIG. 10(   a ); 
         FIG. 11  is a plan view of an ink ribbon cartridge as viewed from the above according to the second embodiment of the invention; 
         FIG. 12  is a plan view of the ink ribbon cartridge of  FIG. 11  as viewed from below; 
         FIG. 13(   a ) is a right side view of an ink ribbon cartridge of  FIG. 11 ; 
         FIG. 13(   b ) is a left side view of the ink ribbon cartridge shown in  FIG. 11 ; 
         FIG. 14(   a ) is a side view of one spool of the ink ribbon cartridge shown in  FIG. 11 ; 
         FIG. 14(   b ) is a plan view of the spool of  FIG. 14(   a ); 
         FIG. 15(   a ) is a plan view of a portion of another spool of the ink ribbon cartridge shown in  FIG. 11 ; 
         FIG. 15(   b ) is an another plan view of the portion of the spool shown in  FIG. 15(   a ); 
         FIG. 16(   a ) is a plan view of another portion of the spool of  FIG. 15(   a ); 
         FIG. 16(   b ) is a plan view of the spool shown in  FIG. 16(   a ); 
         FIG. 17  is a plan view of still another spool of the ink ribbon cartridge shown in  FIG. 11 ; 
         FIG. 18  is a cross-sectional view showing the spool of  FIG. 17  attached to a cartridge case of the ink ribbon cartridge; 
         FIG. 19  is side view showing operations for mounting an ink ribbon into the cartridge case of the ink ribbon cartridge according to a third embodiment of the invention; 
         FIG. 20  is a perspective view of an alternative embodiment of the ink ribbon cartridge case of the invention; 
         FIG. 21  is a perspective view of an alternative embodiment of the ink ribbon cartridge case of the invention; 
         FIG. 22  is a perspective view of an alternative embodiment of the ink ribbon cartridge case of the invention; 
         FIG. 23  is a perspective view of an alternative embodiment of the ink ribbon cartridge case of the invention; and 
         FIG. 24  is a perspective view of an alternative embodiment of the ink ribbon cartridge case of the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     An ink ribbon cartridge according to preferred embodiments of the invention will be described while referring to the accompanying drawings. In the following description, the expressions “front”, “rear”, “left”, “right”, “upper”, and “below” are used throughout the description to define the various parts when the printer is disposed in an orientation in which it is intended to be used. 
     First, a general configuration of a facsimile machine  1  in which an ink ribbon cartridge of the invention is used will be described while referring to  FIG. 1 . It should be noted that the facsimile machine  1  shown in  FIG. 1  functions both as a facsimile machine and as a printer. Specifically, the facsimile machine  1  retrieves images from a document  8 , and transmits image data to another facsimile machine over a telephone circuit. The facsimile machine  1  also receives image data from remote facsimile machines and forms images on recording sheets  4  accordingly. Further, the facsimile machine  1  receives print data transmitted from a word processor or a personal computer over a printer cable or some wireless configuration, such as infrared ray transmission system, and forms an image on the recording sheet  4  based on the print data. 
     As shown in  FIG. 1 , the facsimile machine  1  includes a main case  2 , an operation panel  3 , a pair of sheet guides  5 , a cover  6 , and a document tray  7 . The operation panel  3  is provided at the upper forward portion of the main case  2  and includes key switches  3   a  and liquid crystal display  3   b . The cover  6  is pivotably disposed at the rear of the main case  2  and is for covering the upper side portion of the main case  2  when closed. The pair of the sheet guides  5  are provided to an inner surface of the cover  6  and are for supporting a stack of recording sheets  4  in a slanting upright posture. The document tray  7  is detachably mounted to the upper surface of the main body  2  at a central position between the front and rear of the main case  2  and supports a document  8 . 
     The facsimile machine  1  also includes, a pair of feed rollers  9 , a contact image scanner (CIS)  10 , a document pressing body  11 , a pair of discharge rollers  12 , and a sheet supply unit  14 . The feed rollers  9  are provided internally to the main body  2  beneath the operation panel  3  and are for feeding the document  8  from the document tray  7  in a document feed direction. The CIS  10  is disposed downstream side of the feed rollers  9  in the document feed direction and is retrieving images formed on the document  8 . The discharge rollers  12  are rotatably disposed for discharging the document  8  out from the main body  2 . 
     The sheet supply unit  14  is provided beneath the sheet guides  5  and includes a sheet supply roller  15 , a separation pad  16 , and a pressing member  17 . The sheet supply roller  15  feeds, from a sheet supply port  13 , one recording sheet  4  at a time in a sheet feed direction. The separation pad  16  is disposed below the sheet supply roller  15  and urges the sheet supply roller  15  using a spring (not shown). The pressing member  17  presses the recording sheets  4  stacked on the cover  6  against the sheet supply roller  15  from a position upstream from the separation pad  16  in the sheet feeding direction. 
     Further, the facsimile machine  1  includes a recording portion disposed below the sheet feed roller  15 . The recording portion includes a roller-shaped platen  20 , a spring  21 , a thermal head  22 , a print mount  23 , and an ink ribbon cartridge  24 . The thermal head  22  is disposed below the platen  20  and urged, by the spring  21 , toward the platen  20 . The thermal head  22  has a plurality of thermal elements for generating heat when energized. The ink ribbon cartridge  24  is disposed over the print mount  23 . 
     The ink ribbon cartridge  24  includes a supply spool  25 , a takeup spool  26 , and an ink ribbon  27 . The supply spool  25  is disposed at a rear portion of the ink ribbon cartridge  21  and the takeup spool  26  is disposed in front of the supply spool  25 . The ink ribbon  27  is wound around the supply spool  25  and the takeup spool  26 , and has one ink surface on which an ink layer is formed. A portion of the ink ribbon  27  extends from the supply spool  25  to the takeup spool  26 , passing above the upper surface of the thermal head  22  and a plate spring tension body  28 , with the ink layer facing upward. 
     A recording sheet  4  is fed from the sheet guide  5  to a position between the platen  20  and the thermal head  22  while in confrontation with the ink layer of the ink ribbon  27 . An image is formed one line at a time on the recording sheet  4  by energizing the thermal elements of the thermal head  22  according to image data. Afterwards, the recording sheet  4  is discharged onto a discharge portion  32  provided at the upper surface of the sheet supply portion  14  by the sheet discharge pad  30  and a pair of sheet discharge rollers  31 . 
     Although not shown in the drawings, a handset is disposed at one side of the main body  2  of the facsimile machine  1 . 
     Next, a configuration of an ink ribbon cartridge  24  according to the first embodiment of the invention will be described while referring to  FIGS. 2 to 8(   b ). 
     As shown in  FIG. 2 , the ink ribbon cartridge  24  includes a cartridge case  35 , the ink ribbon  27 , a pair of right and left supply spools  36   a ,  36   b , a pair of right and left takeup spools  36   c ,  36   d , a cylindrical supply tube  40 , and a cylindrical takeup tube  41 . Each of the supply tube  40  and the takeup tube  41  has right and left ends. The supply spools  36   a ,  36   b  are fitted into the right and left ends of the supply tube  40 , respectively, and the takeup spools  36   c ,  36   d  are fitted into the right and left ends of the takeup tube  41 , respectively. It should be noted that the supply spools  36   a ,  36   b  serve as the supply spool  25  shown in  FIG. 1 , and the takeup spools  36   c ,  36   d  serve as the takeup spool  26  shown in  FIG. 1 . Each of the supply spools  36   a ,  36   b  and the takeup spools  36   c ,  36   d  (hereinafter collectively referred to as “spools  36 ”) is integrally formed by, for example, compound resin injection molding. 
     The ink ribbon  27  is formed from a broad-width resin film and has the ink surface on which the ink layer is formed. As shown in  FIG. 2 , the ink ribbon  27  is wound around the supply tube  40  and the takeup tube  41 , which are made from paper. 
     Next, configuration of the spools  36  will be described. 
     First, the supply spool  36   a  will be described. It should be noted that the supply spool  36   a  and the takeup spool  36   c  have the same configuration, a description for the takeup spool  36   c  will be omitted. As shown in  FIGS. 3 and 4 , the supply spool  36   a  has a cylindrical inner shaft  42   a , a flange  43   a , and a cylindrical supporting shaft  44   a . The flange  43   a  has a diameter greater than a diameter of the supporting shaft  44   a . The inner shaft  42   a  is detachably fitted in the right end of the supply tube  40 , and is formed with engagement protrusions  45   a  adjacent to the flange  43   a . The engagement protrusions  45   a  are for fitting in engagement grooves (not shown) formed to the supply tube  40  so that the inner shaft  42   a  will not rotate with respect to the supply tube  40 . 
     The supporting shaft  44   a  is formed with a plurality of protruding ribs  46   a  at its outer peripheral surface. The protruding ribs  46   a  are separated by an appropriate distance from one another in a circumferential direction of the supporting shaft  44   a . The protruding ribs  46   a  are provided for preventing the shaft  36   a  from idly rotating around the axis of the supporting shaft  44   a.    
     The takeup spool  36   c  has a cylindrical inner shaft  42   c , a flange  43   c , and a cylindrical supporting shaft  44   c . The flange  43   c  has a diameter greater than a diameter of the supporting shaft  44   c . The inner shaft  42   c  is detachably fitted in the right end of the takeup tube  41 , and is formed with engagement protrusions (not shown) adjacent to the flange  43   c . The engagement protrusions are for fitting in engagement grooves (not shown) formed to the takeup tube  41  so that the inner shaft  42   c  will not rotate with respect to the takeup tube  41 . 
     Next, the supply spool  36   b  will be described. As shown in  FIGS. 5 and 7 , the supply spool  36   b  has a cylindrical inner shaft  42   b  for fitting in the left end of the supply tube body  40 , a flange  43   b , a cylindrical supporting shaft  44   b , a gear  48   b , a supporting shaft  44   b , and an outer shaft  49   b . The flange  43   b  has a diameter greater than the diameter of the supporting shaft  44   b . The gear  48   b  is provided outside of the flange  43   b.    
     The inner shaft  42   b  is formed with engagement protrusions  45   b  adjacent to the flange  43   b . The engagement protrusions  45   b  are provided in a predetermined arrangement for fitting into grooves (not shown) formed to the left end of the supply tube  40 . A plurality of protruding ribs  46   b  are formed to an outer peripheral surface of the supporting shaft  44   b  so as to be separated by an appropriate distance in the circumferential direction of the supporting shaft  44   b . It should be noted that the configuration and the dimensions of the inner shaft  42   b  and the flange  43   b  are the same as those of the inner shaft  42   a  and the flange  43   a  of the supply spool  36   a.    
     Next, the takeup spool  36   d  will be described. As shown in  FIGS. 6 and 7 , the takeup spool  36   d  has a configuration and dimensions similar to those of the supply spool  36   b . That is, the takeup supply spool  36   d  has a cylindrical inner shaft  42   d  for fitting in the left end of the takeup tube body  41 , a flange  43   d , a cylindrical supporting shaft  44   d , a gear  48   d , a supporting shaft  44   d , and an outer shaft  49   d . However, as shown in  FIG. 6 , a supporting shaft  44   d  has a diameter greater than a diameter of the supporting shaft  44   b  of the supply spool  36   b . Also, although not shown in the drawings, engagement protrusions  45   d  formed to the inner shaft  42   d  have an arrangement different from that of engagement protrusions  45   b . That is, because the engagement protrusions of the other spools (e.g.,  45   a ,  45   b ) are formed in the same arrangement, the engagement protrusions  45   d  are formed in the arrangement different from that of all the other engagement protrusions. 
     As described above, each end of the supply tube  40  and the takeup tube  41  is formed with the grooves (not shown) for engaging with the engagement protrusions  45  of the corresponding spool  36 . Grooves are formed at the left end of the takeup tube  41  with an arrangement that is different from the arrangement of the grooves at the right and left ends of the supply tube  40  and at the right end of the takeup tube  41 . 
     With this configuration, the takeup spool  36   d  can be engaged with the left end of the takeup tube  41 . In this way, the position where the takeup spool  36   d  is mounted is restricted. 
     Next, an explanation for configuration of the cartridge case  35  will be provided while referring to  FIGS. 2 ,  3 . The cartridge case  35  includes a supply-side upper cover  35   a , a takeup-side upper cover  35   b , a pair of connection ribs  52 ,  53 , and side plates  51   a ,  51   b ,  51   c ,  51   d  (hereinafter referred to collectively as “side plates  51 ”). All of these components are integrally formed by, for example, compound resin injection molding. The supply-side upper cover  35   a  and the takeup-side upper cover  35   b  are elongated in the left and right directions. A protrusion A protrudes upwards from an upper surface of the takeup-side upper cover  35   b . The protrusion A is formed with a plurality of ribs  60  extending in a vertical direction along a side surface of the protrusion A. As shown in  FIG. 9(   a ), the protrusion A has an upper surface that is slanted with respect to the horizontal direction. A grooved portion B is formed in an outer side surface of the takeup-side upper cover  35   b . The connection rib  52  connects the left end of the supply-side upper cover  35   a  to the left end of the takeup-side upper cover  35   b . Similarly, the connection rib  53  connects the right end of the supply-side upper cover  35   a  to the right end of the takeup-side upper cover  35   b . A portion C extends along the connection rib  53 . As a result, the connection ribs  52 ,  53 , the supply-side upper cover  35   a , and the takeup-side upper cover  35   d  define a window portion  54 . When the ink ribbon cartridge  24  is mounted to the facsimile machine  1 , a portion of the ink ribbon  27  extending between the supply tube  40  and the takeup tube  41  is exposed through the window portion  54  to the platen  20  above, the connection ribs  52 ,  53  have grooves  70   b ,  70   a , respectively, corresponding to and allowing space for the platen  20 , and the thermal head  22 , the tension body  28 , and the print mount  23  below. The grooves  70   a ,  70   b  are aligned with one another, having an axis therebetween at least parallel to the axis of the platen  20  and perpendicular to the connection ribs  52 ,  53 . The grooves have a profile to permit receipt of the platen ( FIGS. 8(   a ),  8 ( b )). Further, a protuberance  75   a ,  75   b  ( FIGS. 8(   a ),  8 ( b )) extends from a lower surface of respective connection ribs  53 ,  52  proximate the connection to the side plate  51   a ,  51   b  supporting the supply spool  36   a ,  36   b . Lastly, a protuberance  76   a ,  76   b  extends from an outer surface of each side plates  51   c ,  51   d  in a direction away from the takeup tube  41  ( FIGS. 2 ,  3 ,  8 ( a ),  8 ( b ) and  9 ( b )). The protuberances extend substantially in parallel to the axis of the platen ( FIG. 2) . 
     As shown in  FIGS. 3 ,  8 ( a ),  8 ( b ), the side plates  51  are disposed where the connection ribs  52 ,  53  connect to the supply-side upper cover  35   a  and the takeup-side upper cover  35   b . The side plates  51  are formed with support openings  55   a ,  55   b ,  55   c ,  55   d  (hereinafter referred to as “support openings  55 ”), respectively. The supporting shafts  44   a  to  44   d  are freely rotatably mounted into corresponding ones of the support openings  55 . Each of the support openings  55  is formed with a downward opening cutout portion defined by edges  550 , and is also formed with a resilient grooves  56 ,  57 . The resilient grooves  56  are formed external to the openings  55  in a curved shape that substantially follows the contour of the support openings  55 . The resilient grooves  57  extend radially from the support openings  55 . The support opening  55   d  has a diameter greater than diameter of the other support openings  55   a ,  55   b ,  55   c.    
     In order to mount spools  36 , mounted with the ink ribbon  27 , into the cartridge case  35 , the supporting shafts  44  of the spools  36  are pressed upward into the corresponding support openings  55 . At this time, the edges  550  of the support openings  55  resiliently bend to allow the supporting shafts  44  through the downward facing cutout portions into the support openings  55 . However, the supporting shafts  44  will not fall out from the support openings  55  once inserted because the width dimension of the cutout portions are smaller than the diameter of corresponding supporting shafts  44 . It should be noted that the large diameter supporting portion  44   d  of the takeup spool  36   d  can only fit in the large support opening  55   d  of the side plate  51   d . Therefore, the position where the takeup spool  36   d  is attached to the cartridge case  35  is restricted to the large support opening  55   d.    
     When the ink ribbon cartridge  24  is mounted in the facsimile machine  1 , the pair of the connection ribs  52 ,  53  of the cartridge case  35  are supported in a predetermined posture. At this time, the outer shafts  49   b ,  49   d  of the supply spool  36   b  and the takeup spool  36   d  are engaged with protrusions formed on a main frame (not shown) of the facsimile machine  1 . Also, the gears  48   b ,  48   d  are brought into meshing engagement with drive force transmission gears (not shown). Further, the supporting shafts  44   a ,  44   c  of the supply spool  36   a  and the takeup spool  36   c  are engaged in protrusions that resiliently protrude from the main frame (not shown). 
     As a result, as shown in  FIG. 8(   a ), the supporting shafts  44   a ,  44   c  of the spools  36   a ,  36   c  are arranged in substantial concentric condition with the support openings  55   a ,  55   c  of the side plates  51   a ,  51   c . At this time, all of the protruding ribs  46   a ,  46   c  on the supporting shafts  44   a ,  44   c  are arranged so as not to contact the inner peripheral surface defining the support openings  55   a ,  55   c . Also, as shown in  FIG. 8(   b ), the supporting shafts  44   b ,  44   d  of the spools  36   b ,  36   d  are arranged in substantial concentric condition with the support openings  55   b ,  55   d  of the side plates  51   b ,  51   d . All of the protruding ribs  46   b ,  46   d  formed on the supporting shafts  44   b ,  44   d  are arranged so as not to contact the inner peripheral surface defining the support openings  55   b ,  55   d . Therefore, the ribbon supply spool  25  and the ribbon takeup spool  26  can smoothly rotate. 
     On the other hand, when the operator lifts up the cartridge case  35  when replacing the ink ribbon  27 , then as shown in  FIG. 9(   a ), the weight of the ink ribbon  27  and the like shifts the supporting shafts  44  down with respect to the cartridge case  35  into contact with the edges  550  of the support shaft openings  55 . As a result, the protruding ribs  46  of the supporting shafts  44  catch on the edges  550 , so that the spools  36 , that is, the supply tube  40  and the takeup tube  41 , are prevented from unintentionally rotating, and the ink ribbon  27  wound around the supply tube  40  and the takeup tube  41  is prevented from loosening. 
     Also, although not shown in the drawings, when the ink ribbon cartridge  24  is placed on a table (not shown), for example, with the supply-side upper cover  35   a  and the takeup-side upper cover  35   b  facing upward, the weight of the cartridge case  35  shifts the support openings  55  down with respect to the supporting shafts  44 . As a result, the protruding ribs  46  of the supporting shafts  44  catch on the edges of the grooves  57 , so that the spools  36  do not unintentionally rotate, and the ink ribbon  27  is prevented from loosening. It should be noted that even when the ink ribbon cartridge  24  is placed on the table upside down, the spools  36  are prevented from rotating in the same manner as when the ink ribbon cartridge  24  is lifted up.  FIG. 9(   b ) shows an example of the protruding ribs  46 . 
     Next, an ink ribbon cartridge according to a second embodiment of the invention will be described with reference to  FIGS. 10(   a ) and  10 ( b ). The ink ribbon cartridge according to the second embodiment is similar to the ink ribbon cartridge  24  of the first embodiment, except that, as shown in  FIGS. 10(   a ) and  10 ( b ), one or a plurality of supplementary protrusions  59  are formed in an appropriate spacing on an inner peripheral surface defining the supporting openings  55 . With this configuration, as shown in  FIG. 10(   a ), when the ink ribbon cartridge is mounted in the facsimile machine  1 , the supporting shafts  44  are arranged in concentric condition with the surface defining the support openings  55  in the same manner as in the first embodiment, and the protruding ribs  46  are arranged so as not to contact with the inner peripheral surface. 
     However, as shown in  FIG. 10(   b ), when the ink ribbon cartridge is lifted up into the air or placed on a table, for example, the supporting shafts  44  shift into an eccentric condition with respect to the support openings  55  so that some of the protruding ribs  46  catch on the supplementary protrusions  59 . In this way, the ink ribbon  27  is prevented from loosening. 
     In the above described first and second embodiments, the protruding ribs  46  are provided to all of the spools  36 . However, the same operations and effects of the above-described embodiments can be achieved by providing protruding ribs  46  to only the supply or the takeup spools or to only left or right side spools. In these cases, the supplemental protrusions  59  can be provided to the corresponding support openings  55  if desired. 
     Also, according to the embodiments described above, when a spent ink ribbon is replaced, the spools are removed from the tubes and attached to new ones. Therefore, the configuration is extremely economical. 
     Further, each spool can be fitted in and removed from a cartridge case of the ink ribbon cartridge by mounting and dismounting the spools into and from supporting openings through the cutout portions. Because there is no need to provide compression coil springs, the configuration of the ink ribbon cartridge is simplified, and operations for mounting and dismounting the spools are also simplified. 
     Also, by simply providing protrusion ribs around supporting portions of the spools, the spools can be prevented from rotating when the ink ribbon cartridge is taken out from the facsimile machine. Therefore, production costs of the ink ribbon cartridge can be reduced. 
     Next, an ink ribbon cartridge  124  according to a third embodiment of the invention will be described while referring to  FIGS. 11 to 18 . It should be noted that the ink ribbon cartridge  124  is used in the facsimile machine  1  in the same manner as in the first embodiment described above. 
     As shown in  FIGS. 11 and 12 , the ink ribbon cartridge  124  includes a cartridge case  135 , an ink ribbon  127 , a pair of right and left supply spools  136   a ,  136   b , a pair of right and left takeup spools  136   c ,  136   d , a cylindrical supply tube  140 , and a cylindrical takeup tube  141 . The supply spools  136   a ,  136   b  and the takeup spools  136   c ,  136   d  are collectively referred to as spools  136 . Each of the tubes  140 ,  141  has right and left ends. The supply spools  136   a ,  136   b  are fitted into the right and left ends of the supply tube  140 , respectively, and the takeup spools  136   c ,  136   d  are fitted into the right and left ends of the takeup tube  141 , respectively. It should be noted that the supply spools  136   a ,  136   b  serve as the supply spool  25  shown in  FIG. 1 , and the takeup spools  136   c ,  136   d  serve as the takeup spool  26  shown in  FIG. 1 . Each of the spools  136  are formed by, for example, compound resin injection molding. 
     The ink ribbon  127  is the same as the ink ribbon  27  described in the first embodiment and is wound around the supply tube  140  and the takeup tube  141 . 
     Next, the spools  136   a ,  136   c  will be described while referring to  FIGS. 14(   a ) and  14 ( b ). It should be noted that because the supply spool  136   a  and the takeup spool  136   c  have the same configuration and dimensions, only the supply spool  136   a  will be described so as to avoid duplication in explanation. As shown in  FIG. 14(   b ), the supply spool  136   a  has a cylindrical inner shaft  142   a , a flange  143   a , and cylindrical supporting shaft  144   a . The inner shaft  142   a  is for fitting in the right end of the supply tube  140 , and is formed with a pair of engagement protrusions  145   a  adjacent to the flange  143   a . As shown in  FIG. 14(   b ), the engagement protrusions  145   a  are arranged at an angle θ 1  of 180 degrees with respect to an axial center of the supporting shaft  144   a . The supporting shaft  144   a  is formed with a plurality of protruding ribs  146   a  at its outer peripheral surface. The protruding ribs  146   a  are separated by an appropriate distance from one another around the circumference of the supporting portion  144   a.    
     The takeup spool  136   c  has a cylindrical inner shaft  142   c , a flange  143   c , and a cylindrical supporting shaft  144   c . The inner shaft  142   c  is for fitting in the right end of the takeup tube  141 , and is formed with a pair of engagement protrusions  145   c  adjacent to the flange  143   c . The engagement protrusions  145   c  are arranged at an angle θ 1  of 180 degrees with respect to an axial center of the supporting shaft  144   c . The supporting shaft  144   c  is formed with a plurality of protruding ribs  146   c  at its outer peripheral surface. The protruding ribs  146   c  are separated by an appropriate distance from one another around the circumference of the supporting portion  144   c.    
     Next, the supply spool  136   b  will be described while referring to  FIGS. 11 ,  12 , and  15 ( a ) to  16 ( b ). As shown in  FIG. 11 , the supply spool  136   b  has a first portion  139   b  and a second portion  138   b  detachably engaged with the first portion  139   b . As shown in  FIGS. 16(   a ) and  16 ( b ), the first portion  139   b  is formed with an inner shaft  142   b , a flange  143   b , and a supporting shaft  144   b . As shown in  FIGS. 16(   a ) and  16 ( b ), the inner shaft  142   b  is formed with a pair of engagement protrusions  145   b  and a pair of attachment holes  163   b  adjacent to the flange  143   b . The engagement protrusions  145   b  are arranged at an angle of 180 degrees with respect to an axial center of the inner shaft  142   b . The attachment holes  163   b  penetrate the inner shaft  142   b  in its radial direction. 
     As shown in  FIGS. 15(   a ) and  15 ( b ), the second portion  138   b  has a gear  148   b , an outer shaft  149   b , and a pair of arms  164   b . Each of the arms  164   b  is formed with an engagement portion  165   b  extending radially outward from the corresponding arm  164   b . The engagement portions  165   b  are engageable in the attachment holes  163   b  formed in the inner shaft  142   b.    
     According to this configuration, when the arms  164   b  are inserted into the support shaft  144   b  against the resilient force of the arms  164   b , the engagement portions  165   b  engage in the attachment holes  163   b , thereby preventing the outer shaft  144   b  from unintentionally separating from the inner shaft  142   b.    
     Next, the takeup spool  136   d  will be described. The takeup spool  136   d  has a configuration and dimensions similar to those of the supply spool  136   b . Therefore, a detailed description of the takeup spool  136   d  will be omitted. The takeup spool  136   d  has a first portion  139   d  and a second portion  138   d  detachably engaged with the first portion  139   d . The first portion  139   d  is formed with an inner shaft  142   d , a flange  143   d , and a supporting shaft  144   d . However, as shown in  FIGS. 11 and 13(   b ), a supporting shaft  144   d  of the takeup spool  136   d  has a diameter greater than a diameter of the supporting shaft  144   b  of the supply spool  136   b . Also, positions where engagement protrusions  145   d  in the takeup spool  136   d  are formed differ from that in the supply spool  136   b . Specifically, as shown in  FIG. 17 , the engagement protrusions  145   d  are arranged at an angle θ 2  of 120 degrees with respect to an axial center of a support shaft  144   d.    
     Next, the supply tube  140  and the takeup tube  141  will be described. As shown in  FIG. 12 , the supply tube  140  is formed with a pair of grooves  160   a  in its right end and a pair of grooves  160   b  in its left end. Similarly, the takeup tube  141  is formed with a pair of grooves  160   c  in its right end and a pair of grooves  160   d  in its left end. Each pair of the grooves  160   a  to  160   d  are for engaging with the corresponding engagement protrusions  145   a  to  145   d  of the spools  136 . Although not shown in the drawings, the grooves  160   d  at the left end of the takeup tube  141  are arranged at an angle of 120 degrees with respect to an axial center of the takeup tube  141 . On the other hand, each pair of the other grooves  160   a  to  160   c  are arranged at an angle of 180 degrees with respect to an axial center of the corresponding tube  140 ,  141 . 
     With this configuration, the takeup spool  136   d  can only be mounted in the left end of the takeup tube  141 . In this way, the position where the takeup spool  136   d  can be attached is restricted. On the other hand, the spools  136   a  to  136   c  are arranged at the same angle θ 1 , and so can fit into any end of the tubes  140 ,  141 , with the exception of the left end of the takeup tube  141 . 
     Next, an explanation for configuration of the cartridge case  135  according to the third embodiment will be provided while referring to  FIGS. 11 to 13(   b ). As shown in  FIGS. 11 and 12 , the cartridge case  135  includes a supply-side upper cover  135   a , a takeup-side upper cover  135   b , a pair of connection ribs  152 ,  153 , and four side plates  151   a ,  151   b ,  151   c ,  151   d . All of these components are formed integrally by, for example, compound resin injection molding. The supply-side upper cover  135   a  and the takeup-side upper cover  135   b  are elongated in the left and right directions. The connection rib  152  connects the left end of the supply-side upper cover  135   a  to the left end of the takeup-side upper cover  135   b . Similarly, the connection rib  153  connects the right end of the supply-side upper cover  135   a  to the right end of the takeup-side upper cover  135   b . As a result, the connection ribs  152 ,  153 , the supply-side upper cover  135   a , and the takeup-side upper cover  135   b  define a window portion  154 . 
     The side plates  151   a  to  151   d  are disposed where the connection ribs  152 ,  153  connect the supply-side upper cover  135   a  and the takeup-side upper cover  135   b . As shown in  FIG. 13(   a ), the side plates  151   a ,  151   c  are formed with support openings  155   a ,  155   c , respectively. Since the side plates  151   a ,  151   c  have the same configuration as the side plates  51   a ,  51   c  of the first embodiment, a detailed description will be omitted. 
     On the other hand, as shown in  FIG. 13(   b ), the side plates  151   b ,  151   d  are formed with circular holes  166 ,  167 , respectively. The circular hole  167  has a diameter greater than a diameter of the circular hole  166 . The circular hole  167  is capable of freely fitting the support shaft  144   d  of the takeup spool  136   d . The circular hole  166  is capable of freely fitting the support shaft  144   b  of the supply spool  136   b , but not the support shaft  144   d  of the takeup spool  136   d.    
     Next, operations for attaching the spools  136   b ,  136   d  to the cartridge case  135  will be described. First, the support shaft  144   d  of the takeup spool  136   d  is fitted into the circular hole  167  from the inner side of the side plate  151   d  so as to protrude outward through the circular hole  167 . Then, the arms  164   d  of the outer shaft  149   d  are inserted into the supporting shaft  144   d  from outside of the side plate  151   d  so that the side plate  151   d  is sandwiched between the flange  143   d  and the gear  148   d . At this time, the engagement, portions  165   d  at the front tip of the arms  164   d  engage into the attachment holes  163   d  of the inner shaft  142   d . In this way, the takeup spool  136   d  is prevented from unintentionally separating from the cartridge case  135 . Then, the supply spool  136   b  is attached to the side plate  151   b  in the same manner as the takeup spool  136   d  described above. Because, as described above, the takeup spool  136   d  has the large diameter support shaft  144   d , the takeup spool  136   d  can only be mounted in the circular hole  167 . Therefore, the position where the spool  136   d  is mounted is restricted with respect to the cartridge case  138 . 
     The diameter of the support shaft  144   b  is smaller than the diameter of the circular hole  166 , and the diameter of the support shaft  144   d  is smaller than the diameter of the circular hole  167 . Therefore, as shown in  FIGS. 18 and 19 , axial lines of the spools  136   b ,  136   d  can be oriented at a slant with respect to the corresponding side plate  151   b ,  151   d . This configuration is advantageous for reasons to be described later. 
     Next, operations for mounting the ink ribbon  127  to the cartridge case  135  will be described. First, as shown in  FIG. 12 , the cartridge case  135  with the spools  136   d ,  136   b  attached thereto is turned upside down, that is, with the upper covers  135   a ,  135   b  facing downward. Then, the left ends of the supply tube  140  and the takeup tube  141  are engaged with the spools  136   b ,  136   d , respectively. At this time, because the axial line of each spool  136   b ,  136   d  can be oriented at a slant with respect to the corresponding side plate  151   b ,  151   d , the supply tube  140  and the takeup tube  141  can be mounted without removing the spools  136   b ,  136   d  from the cartridge case  135 , and moreover without the ink ribbon  127  bumping against the cartridge case  135 . Also, because the left end of the takeup tube  141  can be engaged only with the takeup spool  136   d , the ink ribbon  127  can be mounted only with a specific orientation to the cartridge case  135 , that is, without mistaking the upper and lower surfaces and right and left sides of the ink ribbon  127 . 
     Next, the spools  136   a  and  136   c  are mounted in the right sides of the supply tube  140  and the takeup tube  141 . It should be noted that because the supply spool  136   a  and the takeup spool  136   c  have the same configuration, the spools  136   a ,  136   c  can be attached to the right end of either the supply tube  140  or the takeup tube  141 . Afterwards, the supporting shafts  144   a ,  144   c  of the spools  136   a ,  136   c  are inserted into the corresponding support openings  155   a ,  155   c . As a result, the axial lines of the tubes  140 ,  141  are oriented perpendicular with respect to the side plates  151   a ,  151   c . Also, in the same manner as in the first embodiment described above, the supporting shafts  144   a ,  144   c  protruding from the right side of the cartridge case  135  are arranged substantially concentric with the inner peripheral surface of the support openings  155   a ,  155   c  thereby preventing the protruding ribs  146   a ,  146   c  from contacting with the inner peripheral surfaces defining the support openings  155   a ,  155   c.    
     When the ink ribbon cartridge  124  is dismounted from the facsimile machine  1 , the protruding ribs  146   a ,  146   c  of the spool  136   a ,  136   c  prevent the spools  136   a ,  136   c , that is, the supply tube  140  and the takeup tube  141 , from rotating in the same manner in the above-described first embodiment. As a result, the ink ribbon  127  wound around the supply tube  140  and the takeup tube  141  will not loosen. 
     According to the third embodiment described above, the operations for exchanging the ink ribbon  127  can be performed without dismounting the spools  136   b ,  136   d  from the cartridge case  135 . Therefore, it is unnecessary for an operator to test to find out the correct combination of spools  136  and side plates  151  each time an operation of exchanging the ink ribbon  127  is performed. Therefore, the operation of exchanging the ink ribbon  127  can be quickly performed. 
     Shown in  FIG. 20  is an alternative embodiment of a cartridge case  235 , for the ink ribbon cartridge, which mounts an ink ribbon (not shown), a pair of right and left supply spools (not shown), a pair of right and left takeup spools (not shown), a cylindrical supply tube (not shown), and a cylindrical takeup tube (not shown). The supply spools and the takeup spools are collectively referred to as spools. Each of the tubes has right and left ends. The spools, tubes and ink ribbon can be as described with respect to either the first or second embodiments. Thus, they will not be described further. 
     The protrusion A protrudes upward from an upper surface of the takeup-side cover  235   b . The protrusion A is formed with ribs  260  at each end of the protrusion. At a center portion of the protrusion A is a handle portion having side segments  261  and an upper surface  262 . Beneath the handle portion is an opening  275  in the takeup-side upper cover  235   b . Although shown as a substantially rectangular opening in  FIG. 20 , the aperture could be an oval, circular, or other similar shape or made up of a plurality of openings formed by reinforcing ribs extending from front to rear, that is across opening  275  between the side closest to the ink ribbon opening and the side toward the front side of the cartridge body. Exemplary alternatives to the rectangular opening  275  shown in  FIG. 20  include an oval opening  277   a , as shown in  FIG. 21 , multiple rectangular openings  277   b  separated by a reinforcing rib  278   b , as shown in  FIG. 22 . multiple oval openings  277   c  separated by a reinforcing rib  278   c . as shown in  FIG. 23 , and multiple circular openings  277   d  separated by reinforcing ribs  278   d , as shown in  FIG. 24 . 
     As in the other embodiments, the cartridge body has a groove B in the front side of the takeup-side upper cover  235   b  and grooves  270   a ,  270   b , aligned with one another, having an axis therebetween that is at least parallel to the axis of the platen  20  and perpendicular to the connection ribs  252 ,  253 . The grooves  270   a ,  270   b  have a profile to permit receipt of the platen. Further, a protuberance  275   b  on connection rib  252 , and a corresponding rib, that is not visible in  FIG. 20 , found on connection rib  253 , extends from a lower surface of the respective connection ribs  252 ,  253  proximate a connection to the side plates  251   b ,  251   a  that support the supply spools. Lastly, a protuberance  276   b  extends from an outer surface of side plate  251   d  in a direction away from the takeup tube. A similar protuberance extends from the side plate at the opposite end of the takeup-side upper cover  235   b , but is not visible in the view shown. These latter protuberances  276   b , unshown, extend substantially in parallel to the axis of the platen. 
     Although the invention has been described in detail with reference to specific embodiments thereof, it would be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention. 
     For example, the ink ribbon cartridge according to the invention is used in a facsimile machine in the above-described embodiments. However, the ink ribbon cartridge of the invention can be used in a printer, a copy machine, or a machine provided with a plurality of these functions. 
     Also, instead of or in addition to the above-described configurations, a portion or all of the side plate  51   d  ( 151   d  or  251   d  (not shown)) can be colored in one color, for example, red, and a portion or all of the corresponding takeup spools  36   d  ( 136   d ) can be colored in the same color, that is, red, as the side plate  51   d  ( 151   d  or  251   d  (not shown)). Also, portions or all of the other three spools  36   a  to  36   c  ( 136   a  to  136   d ) can be colored in a different color, such as green, instead of red. Moreover, the left end of the takeup body  41  ( 141 ) can be colored in the first color (red). With this configuration, the operator can mount the ink ribbon with the correct orientation, that is, with the upper side facing up and right and left side facing right and left into the cartridge case  35  ( 135 ,  235 ) by arranging the same colored portions with extreme ease. In addition to this, the side plates of the cartridge case can also be colored in a different color so that the operator can recognize the right and left sides of the cartridge case  35  ( 135 ,  235 ).