Abstract:
A compact system adapted for card imaging, card laminating, or other card processing, comprises a card processor positioned on a horizontal card feed path and configured to process one or both faces of a rectangular card such as a plastic credit or debit card. A card feeder is arranged to feed cards one at a time onto the horizontal feed path upstream of the card processor, the feeder comprising a compartment for holding a stack of vertical cards each supported on a long edge and a card feed mechanism configured to successively draw a card from an end of the stack and translate it off the stack. A card re-director is configured to receive the card and to redirect it to an attitude in which it is parallel with the horizontal card feed path and positioned to be fed to the card processor along the horizontal feed path. The compartment is located above the horizontal card feed path, and the card feeder feeds cards substantially vertically downward into the card re-director. The card processor may comprise a card printer and a magnetic strip encoder. Also disclosed are methods of printing, encoding and feeding cards.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of U.S. nonprovisional patent application Ser. No. 10/690,395 filed Oct. 20, 2003, for “Substrate Cleaning Apparatus and Method”. This application further claims priority from U.S. provisional application No. 60/536,621 filed Jan. 14, 2004 for “Card Printer and Method of Printing on Cards”. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to card printers for applying information in the form of images, text and the like on one or both of the faces of cards, and particularly to a card printer that is compact both vertically and horizontally. The invention further relates to a method of printing on cards. Still further, the invention relates to the feeding of cards in succession from a stack of cards and particularly to a card feed apparatus and method for feeding cards of various thicknesses while inhibiting the feeding of more than one card at a time from the card stack.  
       BACKGROUND OF THE INVENTION  
       [0003]     Various kinds of cards are becoming more prevalent for such purposes as security (for example, identification cards and badges), financial transactions (credit and debit cards), driver&#39;s licenses, and so forth. These cards are typically made of plastic but may also comprise paper or cardboard. The cards may have printed or embossed characters, magnetic strips, and/or other images or indicia on one or both faces. Although the length and width of these cards have been substantially standardized, card thicknesses may vary considerably.  
         [0004]      FIG. 1  shows a plastic card  10  typical of those in use today. The card  10  has a front face  12 , a rear face  14  carrying a longitudinally-extending magnetic strip  16 , and a generally rectangular geometry comprising a pair of opposed, parallel, longitudinally-extending long edges  18  and  20  and a pair of opposed, parallel, transversely-extending short edges  22  and  24 . The card  10  has a longitudinal or major central axis  26  and a transverse or minor central axis  28 .  
         [0005]     Conventional printers for printing information on discrete cards such as that shown in  FIG. 1  comprise a linear series of processing stations or modules generally including a card feeder, a card flipper or inverter, a print mechanism and a card discharge station. A typical card feeder has a vertical hopper designed to receive a supply of horizontally oriented cards stacked one on top of another. A lifter under the stack urges the stack upwardly to progressively raise the stack as cards are successively withdrawn from the top. The card feeder supplies the cards to the card inverter that rotates each card as necessary and transfers it to and from the card print mechanism in a sequence of steps whereby one or both faces of the card are printed. In conventional printers, the card inverter rotates the card about its shorter or minor central axis  28  ( FIG. 1 ). The print mechanism typically comprises a thermal printhead cooperating with a thermal transfer ribbon or dye sublimation ribbon to print information on a face of each card as the card is fed lengthwise past the print mechanism.  
         [0006]     The present invention addresses several drawbacks of conventional card printers. For example, because the various stations or modules of conventional card printers are arranged in a row, such printers take up considerable desktop space. Moreover, because the cards are stored as a vertical stack in the card supply hopper, conventional card printers tend to be tall. Contributing to their height (as well as to their length) are the card inverters or flippers that rotate the cards around their minor axes. Besides using space inefficiently, existing card printers, because of their size, cost more to manufacture requiring, for example, larger, more expensive enclosures.  
         [0007]     In addition, most conventional card feeders have a fixed slot or gate at the discharge of the card supply hopper through which the cards are passed out of the hopper. The width of the gate is usually set to accommodate one particular card thickness and must be manually readjusted to accept cards having other thicknesses. This is undesirable because it is difficult to measure and to set a gate to accurately feed cards of widely varying thicknesses without double feeding. Double feeding occurs when the card being fed from the top of a stack of cards drags the next card below along with it. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     Various objects, features and advantages of the present invention will become evident to those skilled in the art from the detailed description below when taken together with the accompanying drawings in which:  
         [0009]      FIG. 1  is a perspective view of a standard plastic card one or both of the faces of which may be printed or otherwise imaged using the printer and method of the present invention;  
         [0010]      FIG. 2  is an exploded, perspective view of a printer in accordance with the invention showing, in simplified form, the overall organization of the principal components of the printer;  
         [0011]      FIG. 3  is a front perspective view of a printer incorporating a specific, exemplary embodiment of the present invention;  
         [0012]      FIG. 4  is a rear perspective view of the printer shown in  FIG. 3 ;  
         [0013]      FIG. 5  is a side elevation view, in cross section, of the printer shown in  FIGS. 3 and 4 ;  
         [0014]      FIG. 6  is a side elevation view, in cross section, of a card feeder forming part of the printer of  FIGS. 3-5 ;  
         [0015]      FIG. 7  is a simplified perspective view of a portion of the card feeder of  FIG. 6 ;  
         [0016]      FIG. 8  is a perspective view of the card feeder showing details of a feed roller drive and a card stack pusher plate mechanism;  
         [0017]      FIG. 9  is a side elevation view, in cross section, of a portion of the card feeder showing details of the mechanism for controlling the motion of the pusher plate;  
         [0018]      FIG. 10  is a bottom perspective view of the card feeder;  
         [0019]      FIG. 11  is a top perspective view of the card feeder;  
         [0020]      FIG. 12  is a another bottom perspective view of the card feeder;  
         [0021]      FIG. 13  is a perspective view of a portion of the card feeder showing details of a torsion spring mechanism for biasing a card return roller;  
         [0022]      FIG. 14  is a side elevation view, in cross section, of a portion of the card feeder illustrating the operation of the card feed mechanism in preventing double card feeding;  
         [0023]      FIG. 15  is a top plan view of a portion a card feeder in accordance with an alternative embodiment of the invention;  
         [0024]      FIG. 16  is a bottom perspective view of a card feeder in accordance with another alternative embodiment of the present invention;  
         [0025]      FIG. 17  is a bottom plan view, partly in cross section, of a portion of the card feeder shown in  FIG. 16 ;  
         [0026]      FIGS. 18-21  are simplified perspective views of portions of card feeders in accordance with further, alternative embodiments of the invention;  
         [0027]      FIG. 22  is a perspective view of a subassembly of the printer shown in  FIGS. 2 and 3 , the subassembly comprising a card feeder overlying a card re-director or rotator, with the card rotator angularly positioned to receive a card from the card feeder;  
         [0028]      FIG. 23  is an end elevation view, in cross section, of the subassembly shown in  FIG. 22 ;  
         [0029]      FIG. 24  is a perspective view of the card rotator shown in  FIG. 22  with the rotator angularly positioned to receive a card from the card feeder;  
         [0030]      FIG. 25  is a perspective view of the subassembly of  FIG. 22 , with the card rotator angularly positioned to transfer a card to a print mechanism of the printer;  
         [0031]      FIG. 26  is a perspective view of the card rotator shown in  FIG. 22  with the rotator angularly positioned to transfer a card to the print mechanism of the printer;  
         [0032]      FIG. 27  is a perspective view of the card rotator without its frame;  
         [0033]      FIG. 28  is another perspective view of the card rotator without its frame;  
         [0034]      FIG. 29  is a transverse cross section view of a portion of the card rotator and its frame;  
         [0035]      FIG. 30  is a perspective view of the frame of the card rotator;  
         [0036]      FIG. 31  is a perspective view of a pivotable feed roller support forming part of the card rotator;  
         [0037]      FIG. 32  is a perspective view of a portion of a card throat-defining structure forming part of the card rotator of the invention;  
         [0038]      FIG. 33  is a perspective view of the card rotator drive gear showing details of the outer surface thereof;  
         [0039]      FIG. 34  is a perspective view of the card rotator drive gear showing details of the inner surface thereof;  
         [0040]      FIG. 35  is an end elevation view of the card rotator drive gear showing the inner surface thereof;  
         [0041]      FIGS. 36-39  are end elevation views of a portion of the card rotator illustrating the operation thereof;  
         [0042]      FIG. 40  is a schematic, top plan view, partly in cross-section of a portion of the card rotator in which the card rotator feed rollers are moved apart to allow a card to enter the card throat of the rotator;  
         [0043]      FIG. 41  is a schematic, side elevation view, partly in cross-section of the card rotator in which the feed rollers are in a position to engage and discharge a card from the card rotator; and  
         [0044]      FIG. 42  is a side elevation view, in cross section, of a portion of the printer of  FIGS. 3 and 4 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0045]     The following description is of a best mode presently contemplated for practicing the invention. This description is not to be taken in a limiting sense but is made merely for the purpose of describing the general principles of the invention whose scope may be ascertained by referring to the appended claims. For example, the present invention is described below in terms of processing of “cards” in terms of printing, encoding, laminating cards. It must be noted that the present invention is applicable for use in any system where are card is feed to the system from a stack of cards, regardless of what the system does with the card after it has been received. For example, the present invention may be used to supply cards to a device that further mills the card, such as by shaping the card, punching or drilling holes in the card, etc.  
         [0046]     Further, it must be understood that the term “card” as used herein should not be limiting. A card, as used herein, refers to any unit of media that is fed from a stack through a path to a system. The card may be paper, plastic, metal, etc. It also may have any desired shape, such as rectangular, square, circular, triangular, etc.  
         [0047]      FIG. 2  shows in block diagram form and  FIGS. 3-5  show in greater detail, a specific, exemplary embodiment of a card processing system  40  in accordance with the present invention. The system  40  comprises a card printer for printing on cards  10  such as that shown in  FIG. 1 . By way of example, the card printer  40  may comprise a thermal transfer card printer of the kind typically used to print information in the form of text, graphics, photographs, and so forth, on plastic cards such as I.D. cards, driver&#39;s licenses, and the like, using a thermal printhead cooperating with a thermal transfer or dye sublimation ribbon carried by a disposable ribbon cartridge.  
         [0048]     The card printer  40  generally comprises a printer body or frame  42  supporting a card feeder  44 ; a card re-director or rotator  46 ; a card processor  48  comprising a card cleaning station  48   a , a card print mechanism  48   b  including a thermal printhead  48   c , a printing platen roller  48   d  and a removable, replaceable cartridge  48   e  containing a printer consumable comprising a transfer medium typically in the form of a thermal transfer or dye sublimation ribbon  48   f ; and a card discharge station  50 .  
         [0049]     In accordance with one aspect of the present invention, the card feeder  44  is positioned above the card rotator  46 . The card rotator  46  receives cards  10  in succession from the card feeder  44  along a first feed path  52 , rotates each card about its long axis  26  and redirects it to move along a second feed path  54  between the card rotator  46  and the print mechanism  48  ( FIGS. 2, 3  and  5 ). The cards  10  are transported along the first feed path  52  with their short edges  22  and  24  parallel with the path  52  and along the second feed path  54  with their long edges  18  and  20  parallel with the path  54 . In the specific, exemplary embodiment shown, the first feed path  52  extends in a generally vertical direction while the second feed path  54 , along which the card processor or print mechanism  48  is located, extends in a generally horizontal direction. As will be explained in greater detail below, cards supplied by the card feeder  44  are rotated through approximately 90° by the card rotator  46  before being transported to the print mechanism  48  for printing on one of the card faces. So processed, the card may then be advanced to the discharge station  50 . Alternatively, in a double-pass printing mode, the card  10  may be returned to the rotator  46  for inversion and delivery back to the print mechanism  48  for printing on the other face of the card followed by discharge of the card from the printer.  
         [0050]     Card Feeder  
         [0051]     With reference now also to  FIGS. 6-14 , there is shown one, specific exemplary embodiment of the card feeder  44 . The card feeder  44  includes a card feeder body  60  defining a card supply compartment  62  for holding a card stack  64  comprising a plurality of cards  10   a ,  10   b ,  10   c , and so forth, to be processed. The compartment  62  contains means  66  for biasing the card stack  64  toward a card feed mechanism  68  that removes the cards  10   a , et seq., in succession from the card supply compartment  62  and prevents or inhibits the removal of more than one card at a time from the stack. The card feed mechanism  68  operates independently of card thickness, the feed mechanism being thus capable of feeding cards of different thicknesses without adjustment.  
         [0052]     The card supply compartment  62  has a generally rectangular configuration and is defined by opposed, parallel side walls  70  and  72 , a fixed front end wall  74  and a bottom wall  76  of the feeder body  60 . The card supply compartment  62  is open at the top for receiving a supply of cards to be fed through a front, transverse, slot-like discharge opening  78  ( FIGS. 6, 10  and  14 ) of fixed size defined by a lower edge  80  of the front wall  74  and a front edge  82  of the bottom wall  76 . The cards are advanced in succession through the opening  78  by means of the card feed mechanism  68  in a generally downward direction (as indicated by the arrow) along the generally vertical, first feed path  52 , toward the rotator  46 .  
         [0053]     The cards  10   a , et seq., placed in the card supply compartment  62  are preferably oriented as best seen in  FIGS. 6 and 7 . More specifically, the cards are preferably stacked with the short edges  22  and  24  extending generally vertically, that is, parallel with the first feed path  52 . Alternatively, the card supply compartment  62  may be configured to receive a stack of cards having their long edges  18  and  20  extending vertically; however, stacking the cards as preferred, with their short edges upright, substantially reduces the overall height of the printer.  
         [0054]     A pusher plate  90 , as seen, for example, in  FIGS. 4, 6 ,  8  and  11 , is mounted for longitudinal translation within the card supply compartment  62  and urges the card stack  64  toward the fixed front end wall  74 . The movable pusher plate  90  is resiliently biased toward the front wall  74  and forms the rear wall of the supply compartment. The pusher plate  90  applies to the rear of the card stack  64  a force that remains substantially constant during depletion of the stack as the cards  10   a , et seq., are withdrawn therefrom.  
         [0055]     The pusher plate  90  is mounted for smooth, stable, jam-free translation within the compartment  62  by means of a spring-loaded mechanism  92  seen in  FIGS. 6, 8  and  9 . The mechanism  92  comprises two pairs of meshed pinions  94 ,  96  and  98 ,  100  secured to the ends of a pair of parallel, upper and lower transverse shafts  102  and  104  mounted on a rear surface  106  of the pusher plate  90 . More specifically, the upper transverse shaft  102  is journaled for rotation in vertical legs  108  and  110  defined by the pusher plate  90  at opposite ends thereof. The lower transverse shaft  104  is journaled for rotation in a central bearing block  112  on the rear surface  106  of the pusher plate  90 . The pinions  94  and  96  mesh with spaced-apart, parallel, horizontal racks  114  and  116  mounted on or made integral with the side wall  70  of the feeder body. Similarly, the pinions  98  and  100  mesh with spaced-apart, parallel, horizontal racks  118  and  120  on the side wall  72 . A pair of torsion springs  122  and  124  wound about the shaft  104  and anchored at their inner ends to the central bearing block  112  and at their outer ends to the respective pinions  96  and  100 , provide the resilient bias that urges the pusher plate  90  against the rear of the card stack. In this connection, the torsion springs  122  and  124  are preloaded, that is, they are wound and mounted so as to be under an initial torsional load. As the pusher plate  90  is manually retracted by the user, the torsion springs  122  and  124  are further wound, the energy so stored being released when the pusher plate  90  advances as the cards in the card stack  64  are withdrawn from the card supply compartment. The torsion springs  122  and  124  are closely wound and have numerous turns (that is, substantial effective lengths) so that as they unwind when the pusher plate  90  moves forward, the force exerted by the springs remains substantially constant. It will be seen that the mechanism  92  constrains the pusher plate  90  to remain upright as the plate is translated in either direction within the compartment.  
         [0056]     The card feed mechanism  68  includes friction drive surfaces, preferably in the form of three rollers  130 ,  132  and  134  at the front of the card supply compartment  62 . The roller  130  comprises a first or primary feed roller that is mounted on a transverse shaft  136  journaled for rotation in the side walls  70  and  72  of the card feeder body at a fixed position above the bottom wall  76 . The first feed roller  130  is centered transversely and its drive surface projects slightly into the card supply compartment  62  so that the leading or first card  10   a  ( FIGS. 6, 7 , and  14 ) in a stack of cards loaded into the compartment frictionally engages the first feed roller  130  in response to the resilient bias exerted by the pusher plate  90 . The roller  132  comprises a secondary feed roller that is mounted on a transverse shaft  138  journaled for rotation in the side walls  70  and  72  at a fixed position below the bottom wall  76  of the card supply compartment. It will be seen in  FIGS. 6 and 14  that a line of tangency contacting the primary and secondary rollers  130  and  132  is parallel with the inner surface of the fixed front end wall  74  of the card supply compartment. Both the primary and secondary rollers  130  and  132  are rotatable in unison by a stepper motor  140  secured to the inner surface of the side wall  72  so as to advance a card  10   a , etc., along the feed path  52 . In this connection, with reference also to  FIG. 8 , the primary and secondary roller shafts  136  and  138  have outer ends  142  and  144 , respectively, projecting from the side wall  72  of the card feeder body  60 . The outer ends  142 ,  144  of the shafts  136 ,  138  carry sprockets  146  and  148 , respectively. Trained about the sprockets  146  and  148  is a toothed timing belt  150  driven by an idler sprocket  152  attached to an idler gear  154  in turn driven by a pinion  156  mounted on the output shaft of the stepper motor  140 .  
         [0057]     As best seen in  FIGS. 7 and 10 , the primary and secondary rollers  130  and  132  have the same lengths. The roller  134  comprises a third or tertiary roller that functions in counteracting fashion to return toward the card stack a second card improperly withdrawn from the card stack along with a correctly fed first card. The tertiary roller  134  is substantially narrower than the primary and secondary rollers  130  and  132  and is mounted on the side opposite the feed path  52  from the primary and secondary rollers and in alignment with and centered on the secondary roller  132 .  
         [0058]     The tertiary roller  134  is mounted on the inner end of a shaft  162  supported by a floating plate  164  in turn carried by a pair of fixed guide pins  166  and  168  projecting from the lower surface of the bottom wall  76  and extending through oversize slots  170  and  172  in the plate  164 . A tension spring  174  anchored between a post  176  near the rear of the plate  164  and a fixed post  178  projecting from the bottom wall resiliently biases the plate  164  to urge the tertiary roller  134  toward the secondary roller  132  and into contact therewith in the absence of a card. The tertiary roller shaft  162  has an outer end  180  projecting from the feeder body side wall  70  through an oversize opening (not shown) permitting floating movement of the plate  164  in response to the presence of cards of different thicknesses between the secondary and tertiary rollers  132  and  134 .  
         [0059]     With reference to  FIGS. 10-14 , and particularly  FIG. 13 , keyed to the projecting outer end  180  of the tertiary roller shaft  162  is a hub  181  secured to a pivotable plate  182  defining spaced-apart abutment surfaces  183  and  184  positioned to engage a fixed post  185  mounted on the feeder sidewall  70 . The plate  182  is retained on the shaft  162  by a snap ring  186 . The shaft  162  and the tertiary roller  134  carried thereby are thus able to pivot within the limits imposed by the spacing between the abutment surfaces  183  and  184 . Wound around the hub  181  is a torsion spring  187  having an inner end  188  bearing against a pin  189  on the pivotable plate  182  and an outer end  188   a  bearing against the fixed post  185  on the feeder sidewall. The torsion spring  187  thus biases the tertiary roller shaft  162  so that it tends to rotationally pivot clockwise as viewed in  FIG. 13 . As noted, the extent of the rotational movement of the plate is limited by the spaced-apart abutment surfaces  183  and  184 .  
         [0060]     The card feed mechanism  68  prevents the removal of more than one card at a time from the card stack  64 . More specifically, when a first, individual card  10   a  passes between the secondary and tertiary rollers  132  and  134  ( FIG. 14 ), a fluctuating pinch is created on the card depending upon the thickness of the card through the spring loaded, floating plate  164  and the tertiary roller  134  carried thereby. With reference to  FIG. 14 , assume now that a second card  10   b , clinging to the first card  10   a  because of a static charge, for example, is erroneously withdrawn from the stack along with the first card  10   a . The torsion spring  187  mounted on the outer end  180  of the tertiary roller shaft  162  winds up in response to the amount of friction between the first and second cards  10   a  and  10   b  versus the amount of friction between the second card  10   b  and the tertiary roller  134 . Because the friction between the tertiary roller  134  and the second card  10   b  is greater than the friction between the first and second cards  10   a  and  10   b , the torsion spring  187  is wound up (to the extent permitted by the limit imposed when the abutment surface  183  engages the post  185 ) causing the spring  187 , when its stored energy is released, to force the second card  10   b  back toward the card stack  64  until the first card  10   a  has exited the zone  160  between the secondary and tertiary rollers.  
         [0061]     The primary and secondary rollers  130  and  132  are preferably made of the same material, for example, silicone. The tertiary roller  134  is preferably made of the same material as the primary and secondary rollers but alternatively may be constructed of a different material such as ethylene propylene diene monomer (EPDM). Further, the primary and secondary rollers  130  and  132  preferably have the same outer diameter. Alternatively, the rollers  130  and  132  may have different diameters in which case they are driven at such angular rates that they have the same peripheral velocity.  
         [0062]     Ideally, the secondary and tertiary rollers  132  and  134  are mounted so that a leading card fed by the primary roller  130  is engaged by both the secondary and tertiary rollers. For example, if the thinnest card intended to be processed has a thickness of 0.008 inch, the maximum spacing between the opposed outer surfaces of the secondary and tertiary rollers might ideally be set at 0.007 inch. However, cumulative tolerances in the various parts of the feeder mechanism may preclude precisely setting that spacing. Accordingly,  FIG. 15  shows an alternative embodiment in which the need for close tolerances between the secondary and tertiary rollers is avoided. More specifically,  FIG. 15  illustrates a secondary roller  500  having a stepped diameter with a smaller diameter portion or circumferential groove  502  in the central part of the roller opposite a tertiary roller  504 . The tertiary roller  504  has an outer card-engaging surface  506  that projects slightly into the groove  502  in the secondary roller  500  to introduce a small degree of overlap between the rollers. This arrangement, which does not depend on tight tolerances, always assures contact between a leading card fed from the card feeder and both of the rollers  500  and  504 ; the slight deflection of the card introduced by this offset arrangement does not affect the operation of the feed mechanism.  
         [0063]      FIGS. 16 and 17  show an alternative embodiment of a card feed mechanism that may be used in the present invention. Like the first embodiment, the alternative embodiment comprises a card feeder body  190  defining a card supply compartment  192  having a fixed discharge opening at the front end thereof through which the cards are advanced along a generally vertical feed path  195 . The feeder body  190  supports a card feed mechanism  196  comprising a first or primary friction drive surface  198 , a second or secondary friction drive surface  200  and a third or tertiary friction drive surface  202 . The drive surfaces  198 ,  200  and  202  preferably take the form of rollers configured and positioned as previously described. The primary and secondary rollers  198  and  200  are driven by a stepper motor  204  also as already described. The tertiary roller  202 , as before, is carried by a shaft  206  journaled for rotation in a floating plate  208  resiliently biased by a tension spring  210  to urge the tertiary roller  202  toward the secondary roller  200  and into contact therewith when no card is present and into engagement with the back face of a card advanced along the feed path  195 .  
         [0064]     An outer end  214  of the tertiary roller shaft  206  projects through an oversize opening  216  in a sidewall  218  of the card feeder body. As in the first embodiment, the opening  216  is larger than the diameter of the tertiary roller shaft  206  to allow the floating plate  208  to be displaced in response to the presence of cards of various thicknesses transported along the feed path  195  between the secondary and tertiary rollers. Fixed to the outer, projecting end of the tertiary roller shaft  206  is a timing belt sprocket  220 .  
         [0065]     A shaft  222  that supports and drives the primary card feed roller  198  has an outer end  224  projecting from the side wall  218 . Mounted on the outer end of the shaft  222  adjacent to the side wall  218  is a collar  226  secured to the shaft so that the collar rotates with the shaft. Disposed adjacent to the outer surface of the collar is a clutch  228  including a fiber washer  230  that functions as a clutch disk. Adjacent to the fiber washer  230  is a sprocket  232  that is free to rotate on the primary feed roller shaft  222 . Disposed between a retainer washer  234  on the outer extremity of the shaft  222  and the outer face of the sprocket  232  is a compression spring  236  that urges the sprocket  232  into frictional engagement with the fiber washer  230 . A timing belt  238  couples the sprocket  232  on the shaft  222  and the sprocket  220  secured to the tertiary roller shaft  206 . It will be seen that the single stepper motor  204  drives all three rollers  198 ,  200  and  202  in the same rotational direction. As a result, while the primary and secondary rollers  198  and  200  tend to advance a card along the feed path  195 , the tertiary roller  202 , being positioned on the side of the feed path  195  opposite that of the primary and secondary feed rollers tends to move the card back toward the card stack. Given the smaller contact area between the tertiary roller  202  and the card and the fact that both the primary and secondary feed rollers urge the card forward along the feed path  195 , the action of the tertiary roller  202  is insufficient to drive a single card back toward the card stack. If a second card is erroneously withdrawn along with the first card, however, the frictional force between the tertiary roller  202  and the second card exceeds the frictional force between the two cards; the latter force tends to be substantially less given the slickness of the abutting card surfaces so that the second card will be driven back toward the card stack by the counteracting tertiary roller  202 .  
         [0066]     When no card is present between the secondary and tertiary rollers  200  and  202 , the tertiary roller is driven by the secondary roller in the opposite rotational direction thereto, the friction between these rollers being sufficient to effect such drive and to cause the clutch  228 , which tends to drive the tertiary roller in the same direction as the primary and secondary rollers, to slip.  
         [0067]     When a single card is advanced through the card discharge opening into the zone between the secondary and tertiary rollers  200  and  202 , the tertiary roller, driven through the clutch  228  in a direction opposite to the forward card feed direction, slips on the back surface of the single card, which is driven forward by the higher drive force exerted by the wider primary and secondary rollers  200  and  202 .  
         [0068]     However, when a second (unwanted) card is drawn out of the card stack along with the first card, the tertiary roller  202 , acting on the back surface of the second card at the leading edge thereof, tends to drive the second card back toward the card stack. Such backward or tertiary drive is effected through the clutch  228  because the friction between the tertiary roller and the second card is greater than the friction between the two cards. In this operation, all three rollers  198 ,  200  and  202  rotate in the same direction.  
         [0069]     In summary, the stepper motor  204 , acting through the clutch  228 , at all times tends to rotate the tertiary roller  202  in the same direction as the primary and secondary rollers  198  and  200 . This tendency is overcome, and the clutch  228  slips, when no card or one card is present in the pinch zone between the secondary and tertiary rollers. It is only when a second card is erroneously withdrawn from the card stack along with a first card, that the tertiary roller rotates in a direction forcing the second card back into the card stack.  
         [0070]     With reference now to  FIGS. 18-21 , there are shown alternative embodiments of the card feed mechanisms  68  and  196  described above for feeding cards  10   a ,  10   b , and so forth, one at a time along a generally vertical first feed path  250 . The embodiment of  FIG. 18  comprises a card feed mechanism  252  including a primary frictional drive surface in the form of an endless belt  254  trained about rotatable drums  256  and  258 , and a secondary frictional drive surface in the form of a roller  260 . The embodiment of  FIG. 19  comprises a card feed mechanism  262  including a primary frictional drive surface in the form of a roller  264  and a secondary frictional drive surface in the form of an endless belt  266 . In the embodiment of  FIG. 20 , a card feed mechanism  268  is provided comprising primary and secondary frictional drive surfaces defined by endless belts  270  and  272 , while in the embodiment of  FIG. 21 , a card feed mechanism  274  combines both the primary and secondary frictional drive surfaces into a single endless belt  276 .  
         [0071]     Card Re-Director or Rotator  
         [0072]     With reference to  FIGS. 4 and 22 - 41 , the card re-director or rotator  46  is mounted on a frame or base  300  for rotation about a central, horizontal axis  302 . The rotator comprises a card receiving, holding and ejecting subassembly  304  comprising a pair of parallel, spaced-apart plates  306  and  308  defining between them a card throat  310  having an elongated card input opening or slot  312  extending parallel with the central axis  302 . The card throat  310  receives each of the cards  10  fed from the card feeder  44  and holds each card during rotation thereof. The card  10  is held against stops (not shown) within the card throat  310  by gravity. The plate subassembly  304  is supported at one end by a disk  314  and at the other end by a stub shaft  316  journaled for rotation in an aperture  318  in an end wall  320  of the base  300  ( FIG. 30 ). The stub shaft  316  projects from the end wall  320  and carries a large, rotator drive gear  322  that can rotate relative to the stub shaft  316 . The disk  314  and the gear  322  lie in vertical, parallel planes and are centered on, and rotatable about, the central axis  302 . The disk  314  defines an elongated, transverse card discharge opening or slot  324  extending along a diameter of the disk in alignment with the card throat  310 . As will be explained, cards are transported from the throat through the rotator discharge slot  324  for loading into the card print mechanism  48 .  
         [0073]     The plate subassembly  304  is rotatably supported at its one end by the disk  314  which has a periphery  326  engaging three equiangularly spaced, flanged disk support wheels  328 ,  330  and  332  mounted for rotation on a side member  334  of the rotator base  300 . The end gear  322  is in mesh with a smaller gear  336  in turn driven by the output shaft of a computer controlled stepper motor  337  ( FIG. 27 ). An optical sensor  338  on the rotator base  300  operatively associated with a photo-interrupter  340  on the disk  314  provides electrical output signals responsive to the angular position of the card rotator. The output signals generated by the optical sensor  338  are coupled to a printer controller along with output signals generated by card edge and other detectors (not shown) for coordinating the operation of the various elements of the printer, in a manner well known in the art.  
         [0074]     The card throat-defining plate  306  carries an arm  350  pivotally mounted on spaced-apart brackets  352  and  354  secured to the plate  306  adjacent to the disk  314  ( FIGS. 28 and 32 , for example). The arm  350  supports a card drive roller  356  mounted on a shaft  358  journaled in the arm  350 . The shaft  358  has an outer end projecting from the arm  350  and carrying a roller drive gear  360 . Similarly, the card throat-defining plate  308  carries an arm  362  pivotally mounted on spaced-apart brackets  364  and  366  attached to the plate  308  adjacent to the support disk  314 . The arm  362  supports a card drive roller  368  mounted on a shaft  370  journaled in the arm  362  The shaft  370  has an outer end projecting from the arm  362  and carrying a roller drive gear  372 . The first-mentioned roller drive gear  360  projects in a direction opposite that of the second-mentioned roller drive gear  372  ( FIG. 29 ). The arm  350  is resiliently biased to pivot and move toward the plate  306  by means of an extension spring  374 ; similarly, the arm  362  is resiliently biased to pivot and move toward the plate  308  by means of an extension spring  376 . It will thus be seen that the arms  350  and  362  are pivotable symmetrically in clam shell fashion between positions in which the rollers  356  and  368  are spaced apart ( FIG. 40 ) and in which the rollers can come into engagement with a card  10  ( FIG. 41 ).  
         [0075]     Turning now to  FIGS. 33-35 , the rotator drive gear  322  has a central sleeve  380  that receives the stub shaft  316 . The gear  322  further includes an arcuate slot  382  concentric with the axis of rotation  302  ( FIG. 22 ). Projecting outwardly from an outer face  384  of the gear adjacent the inner edge of the arcuate slot  382  at the midpoint thereof is a lug  386 . When the gear  322  is mounted on the stub shaft  316 , the lug  386  is in alignment with a corresponding lug  388  projecting from the gear end of the throat-defining plate subassembly  304 .  
         [0076]     Projecting from an inner face  390  of the gear  322  is a pair of cams  392  and  394  disposed symmetrically with the arcuate slot  382  and lug  386 . The pivotable arms  350  and  362  include outer ends  396  and  398 , respectively, positioned to be engaged by the cams  392  and  394 , respectively, so that relative rotational motion between the gear  322  and the subassembly  304  will cause the arms  350  and  362  (and hence the rollers  356  and  368 ) to be moved apart against the bias of the springs  374  and  376  or toward each other under the bias of the springs.  
         [0077]     The central sleeve  380  on the gear  322  carries a torsion spring  400  having crossed ends  402  and  404  engaging the sides of the aligned lugs  386  and  388 . The lugs are thereby held in alignment under the torsional bias of the torsion spring  400 . Accordingly, rotation of the gear  322  will cause the throat-defining plate subassembly  304  to follow, that is, the gear  322  and the subassembly  304  will rotate in unison. With the lugs  386  and  388  in alignment as shown, for example, in  FIG. 38 , the cams  392  and  394  on the gear  322  are disposed to lift the arms  350  and  362  to keep the rollers  356  and  368  apart.  
         [0078]     Operation  
         [0079]     In the operation of the printer, the card re-director or rotator  46  is rotated to an initial position shown in  FIGS. 22-24 ,  27 - 29 ,  36  and  40 , in which the card throat  310  is in alignment with the first feed path  52 . In this position, the throat  310  is disposed to receive a card  10  withdrawn from the card stack  64  and advanced by the card feed mechanism  68  along the first feed path  52 . It will be seen that in the specific, exemplary embodiment illustrated the feeder compartment  62  is slightly tipped with the bottom wall  76  of the feeder sloping down toward the front wall  74 . This orientation both assists the user&#39;s manual loading of the feeder compartment  62  and adds gravity bias to help urge the card stack  64  toward the front wall  74  of the compartment without appreciably increasing the overall height of the printer. The angle is preferably that at which sliding of the card stack  64  impends, for example, about 15° for a given angular coefficient of friction in accordance with one practical embodiment. Although such a tipped orientation is preferred, it will be evident that the compartment  62  may be horizontal so that the orientations of both the cards in the stack and the first feed path  52  are vertical.  
         [0080]     As noted, the cards in the stack are preferably oriented with their short edges  22  and  24  substantially vertical, thereby helping to minimize the height of the printer. It will also be appreciated that this card orientation, carried over to the card rotator  46 , means that a card will be rotated by the rotator about its major or longitudinal axis  26  instead of around its minor or transverse axis  28  as in conventional printers. Thus, height reduction is achieved by printers of the present invention while at the same time reducing the printer&#39;s length by placement of the card feeder  44  above the card rotator  46 .  
         [0081]     With the rotator  46  positioned rotationally so that the throat  310  is in a substantially vertical position, the arms  350  and  362  are engaged by the cams  392  and  394  and are thus in their spaced-apart orientation. ( FIG. 40 .) With the rollers  356  and  368  correspondingly spaced apart, a card  10  is fed from the feeder  44  into the throat. The gear  322  is rotated in one direction or the other depending upon which face of the card is to be printed, the gear  322  and the throat subassembly  304  rotating in unison by virtue of the torsion spring  400 . ( FIGS. 36 and 37 .) When the throat subassembly reaches the horizontal position ( FIG. 38 ) further rotation of the subassembly is arrested by one of a pair of stops  410  and  412  on the base ( FIGS. 30, 38  and  39 ).  
         [0082]     A sensor is activated at this time by the photo interrupter  340 ; the output of the sensor turns off the stepper motor driving the gear  322 . Once the card throat is aligned with the horizontal plane ( FIGS. 25, 26 ,  38 ,  39  and  41 ), the stepper motor is turned on again and by counting a number of steps the motor, through the gear  322 , will begin to further rotate the gear  322  against the bias of the torsion spring  400 ; as noted, the throat subassembly  304  is held by one of the stops  410  and  412  against further movement. As seen in  FIG. 39 , this further rotation of the gear  322  causes the cams  392  and  394  on the gear  322  to come out of engagement with the arms  350  and  362 , allowing these arms to move toward each other under the bias of the extension springs  374  and  376  thereby causing the card feed rollers  356  and  368  to engage the opposed faces of the card  10  in the throat  310  ( FIG. 38 ). As seen in  FIGS. 4, 24 ,  26 ,  28  and  29 , in the horizontal orientation of the throat, one or the other of the roller drive gears  360  and  372  will mesh with a drive pinion  414  carried by the base  300 . Actuation of the drive pinion  414  through a belt driven pulley  416  causes the rollers  356  and  368  to rotate and eject the card  10  through the end discharge slot  324  of the rotator and toward the print mechanism  48 .  
         [0083]     If a card is to have both sides printed, the card is driven back into the card throat  310  along the horizontal path  54  in a reverse direction and back into the rotator  46 . The rotator rotates in reverse, moving 180° to flip or invert the card after which the card is driven out of the rotator and printed on the other side. In this operation, the drive pinion  414  will engage the roller drive gear  360  or  372  on the other arm  350  or  362 .  
         [0084]     With reference to  FIG. 42  and again to  FIG. 5 , the card printer  40  may also be used to magnetically encode the magnetizable strips on cards processed by the printer. One of the problems encountered during encoding is card “jitter” which tends to degrade the quality of the encoding. Such “jitter” may be caused by the card striking a set of rollers. With reference to  FIG. 5 , a card drive roller  600  is positioned at a card encoding station along the horizontal feed path  54  between the card cleaning station  48   a  and the printing platen roller  48   d . The drive roller  600  is a “half” roller, extending only part way across the width of the card feed path  54  so that the roller does not contact the magnetic strip of a card being transported. Mounted adjacent to the roller  600  and in transverse alignment therewith is a magnetic head  602  ( FIG. 42 ) for encoding the magnetic strip as the card is transported past the head by the “half” roller  600 .  
         [0085]     The card cleaning station  48   a  comprises the stacked combination of primary “sticky” roller  604  and a secondary “sticky” roller  606 . The rollers  604  and  606  are normally resiliently biased downwardly toward the card path  54  but may be selectively moved upwardly away from the path  54  by a cam mechanism (not shown).  
         [0086]     In a magnetic encoding operation, a card is driven out of the throat  310  of the card re-director or rotator  46  along the path  54  (to the left as seen in  FIG. 5 ) by means of the drive rollers  356  and  368 . The card is further driven to the left by the “half” roller  600  until the card clears the cleaning station  48   a  and the trailing edge of the card is at the roller  600 . The cleaning rollers  604  and  606  as well as the rotator drive rollers  356  and  368  are then cammed away from the card path  54 . At this point, the card is driven back by the roller  600  towards the throat  310  with the magnetic strip moving past the magnetic head  602 . It is during this reverse pass that the card strip is magnetically encoded by the head  602 . It will be appreciated that with the rollers  356 ,  368 ,  604  and  606  clear of the card path  54  during this encoding operation, the card will not strike any structure that might otherwise cause “jitter” and a possible failure of the encoding process.  
         [0087]     As noted, the card rotator  46  is constructed and the card input and discharge slots  312  and  324  are so positioned that a card is oriented for rotation about its short edges to conserve space, but oriented for printing in a direction parallel with its long edges. It would be possible, of course, to eliminate the transverse discharge slot  324  and feed cards both into and out of the slot  312  with the print mechanism appropriately positioned to receive the cards from the slot  312 . This means that the application of information to the card face(s) would take place as each card is transported in the direction parallel with the short edges thereof.  
         [0088]     While several illustrative embodiments of the invention have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Such variations and alternate embodiments are contemplated, and can be made without departing from the spirit and scope of the invention as defined in the appended claims.