Abstract:
A method for determining a mismatch involving the availability of a dye donor supply and a dye receiver supply in a thermal printer when a particular print size and print quantity are selected, comprises: comparing a remaining number of similar-size donor patches available on the dye donor supply with a remaining number of like-size donor patches required for the selected print size and print quantity, and should the former number be less than the latter number providing a warning; and comparing a remaining length of dye receiver available on the dye receiver supply with a remaining length of dye receiver required for the selected print size and print quantity, and should the former length be less than the latter length providing a warning.

Description:
FIELD OF THE INVENTION 
     The invention relates generally to thermal printers, and in particular to one in which a mismatch involving the availability of a dye donor supply and a dye receiver supply can be determined—in which case the printing operation should be suspended and the short supply replenished to establish a match. 
     BACKGROUND OF THE INVENTION 
     A typical dye donor web that is used in a thermal printer includes a repeating series of three different primary color sections or patches such as a yellow color patch, a magenta color patch and a cyan color patch. Also, there may be a transparent colorless laminating section or patch after the cyan color patch. 
     To make a color image print using a thermal printer, respective color dyes in a single series of yellow, magenta and cyan color patches on a dye donor web are successively heat-transferred, one over the other, onto a dye receiver sheet. Then, optionally, a transparent laminating material on a laminating patch of the web is heat-transferred onto the color image print. The dye transfer from each color patch to the dye receiver sheet is done one line of pixels at a time via a bead of selectively used heating or resistor elements on a thermal print head. 
     One example of a color image print-making process using a thermal printer is as follows. 
     1. A dye donor web and a dye receiver sheet are advanced forward in unison, with a yellow color patch of the donor web moving in contact with the receiver sheet longitudinally over a stationary bead of heating elements in order to effect a line-by-line yellow dye transfer from the yellow color patch to the receiver sheet. A web take-up spool draws the dye donor web forward over the bead of heating elements, and a pair of pinch and drive rollers draw the dye receiver sheet forward over the bead of heating elements. A platen roller holds the dye receiver sheet in a dye receiving relation with the dye donor web at the bead of heating elements. 
     2. Once the yellow dye transfer is completed, the platen roller is retracted from adjacent the print head to allow the pair of pinch and drive rollers to return the dye receiver sheet rearward in preparation for a second pass over the bead of heating elements. 
     3. Then, the platen roller is returned to adjacent the print head, and the dye donor web and the dye receiver sheet arc advanced forward in unison, with a magenta color patch of the donor web moving in contact with the receiver sheet longitudinally over the bead of heating elements in order to effect a line-by-line magenta dye transfer from the magenta color patch to the receiver sheet. The magenta dye transfer to the dye receiver sheet is in the same area on the receiver sheet as was subjected to the yellow dye transfer. 
     4. Once the magenta dye transfer is completed, the platen roller is retracted from adjacent the print head to allow the pair of pinch and drive rollers to return the dye receiver sheet rearward in preparation for a third pass over the bead of heating elements. 
     5. Then, the platen roller is returned to adjacent the print head, and the dye donor web and the dye receiver sheet are advanced forward in unison, with a cyan color patch of the donor web moving in contact with the receiver sheet longitudinally over the bead of heating elements in order to effect a line-by-line cyan dye transfer from the cyan color patch to the receiver sheet. The cyan dye transfer to the dye receiver sheet is in the same area on the receiver sheet as was subjected to the yellow and magenta dye transfers. 
     6. Once the cyan dye transfer is completed, the platen roller is retracted from adjacent the print head to allow the pair of pinch and drive rollers to return the dye receiver sheet rearward in preparation for a fourth pass over the bead of heating elements. 
     7. Then, the platen roller is returned to adjacent the print head, and the dye donor web and the dye receiver sheet are advanced forward in unison, with a transparent colorless laminating patch of the donor web moving in contact with the receiver sheet longitudinally over the bead of heating elements in order to effect a line-by-line laminating material transfer from the laminating patch to the receiver sheet. The laminating material is applied to the dye receiver sheet on top of the yellow, magenta and cyan dye transfers to that sheet. 
     8. Once the laminating material transfer is completed, the platen roller is retracted from adjacent the print head to allow the laminated dye receiver sheet to be returned rearward in preparation for exiting the printer. 
     9. Finally, the pair of pinch and drive rollers advance the laminated dye receiver sheet forward to an exit tray. 
     Instead of a dye receiver sheet, the print-making process can involve a dye receiver roll. In this case, each sheet must be cut from the roll. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, a method for determining a mismatch involving the availability of a dye donor supply and a dye receiver supply in a thermal printer when a particular print size and print quantity are selected, comprises: 
     comparing a remaining number of similar-size donor patches available on the dye donor supply with a remaining number of like-size donor patches required for the selected print size and print quantity, and should the former number be less than the latter number providing a warning; and 
     comparing a remaining length of dye receiver available on the dye receiver supply with a remaining length of dye receiver required for the selected print size and print quantity, and should the former length be less than the latter length providing a warning. 
     According to another aspect of the invention, apparatus is provided for performing the foregoing method. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram of printer apparatus which is a preferred embodiment of the invention; and 
     FIGS. 2-4 is a flow chart depicting a method operating the printing apparatus. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Because the features of a thermal printer are generally known, the description which follows is directed in particular only to those elements forming part of or cooperating directly with the invention. It is to be understood, however, that other elements not disclosed may take various forms known to a person of ordinary skill in the art. 
     Thermal Printer—FIG. 1 
     FIG. 1 depicts, in part, a thermal printer  10  in which a donor cartridge  12  having a dye donor web  14  intended to be advanced from a rotated (fresh) donor supply roll  16  to a rotated (used) donor take-up roll  18  is loaded. The dye donor web  14  is a conventional one including a repeating series of four successive similar-size donor sections or patches (not shown). Each one of the series has three different primary color patches, such as a yellow color patch, a magenta color patch and a cyan color patch, and a transparent colorless laminating patch immediately following the cyan color patch. All four donor patches are used once to make a single print. Also, loaded in the printer  10  is a rotated paper supply roll  20  including a paper web  22 . The paper web  22  is a dye receiver web. 
     The printer  10  comprises: 
     a donor roll mark (optical) sensor  24  for sensing coaxial code marks  26  on the rotated donor supply roll  16  to determine the roll speed/existing roll diameter and the size, i.e. width W×length L in inches (″), of each donor patch on the donor web  14 , using a suitable programmed computer  28 ; 
     a light emitter  30 , such as a light-emitting diode, and a known light-responsive detector  32  that constitute a leading patch edge sensor for sensing successive leading edges of the four donor patches used to make a single print; 
     a counter (not shown) in the computer  28  for counting each patch when its leading edge is sensed by the leading patch edge sensor  30 ,  32 , and which is reset to zero (“0”) whenever the cartridge  10  is removed from the printer  10  or a new print-making operation is begun; 
     a print head  34  for heat-transferring the yellow, magenta, and cyan color dyes, and the laminating material, from the four donor patches to the same length of the paper web  22  as previously described in the “BACKGROUND OF THE INVENTION”; 
     a paper roll mark (optical) sensor  36  for sensing coaxial code marks  38  on the rotated paper supply roll  20  to determine the roll speed/existing roll diameter and the paper width W in inches (″), using the computer  28 ; 
     a paper cutter  40  for severing a print length from the paper web  22  once the yellow, magenta, and cyan color dyes, and the laminating material, are heat-transferred from the four donor patches to the same length of the paper web  22 ; 
     a paper cut (switch) sensor  42  for sensing each paper cut; 
     a paper roll removal (switch) sensor  44  for sensing removal of the paper supply roll  20 ; 
     a counter (not shown) in the computer  28  for counting each paper cut, and which is reset to zero (“0”) whenever the paper supply roll  20  is removed from the printer  10  or a new print-making operation is begun; and 
     a guide roller  46  for the donor web  14 , a support roller  48  (movable towards and away from the printer head  34 ) for the donor web as well as for the paper web  22 , a pinch roller  50  and a capstan roller  52  for the donor and paper webs, and guide roller  54  for the donor web. 
     The donor roll mark sensor  24 , the light emitter  30 , the light-responsive detector  32 , the paper roll mark sensor  36 , the paper cut sensor  42 , and the paper roll removal sensor  44  are individually connected to a circuit board  56  which in turn is connected to the computer  28 . A single-direction motor (not shown) is connected to the donor supply roll  16  for rotating it in unwinding direction, and a single-direction motor is connected to the rotated donor take-up roll  18  for rotating it in a winding direction. A bi-direction motor (not shown) is connected to the rotated paper supply roll  20  for rotating it in an unwinding direction. A bi-directional motor (not shown) is connected to the capstan roller  52  for rotating it in forward and reverse directions. All of the motors are connected to the computer  28 . 
     Method—FIGS. 2,  3  and  4   
     To start (FIG. 2) a cycle for the print-making operation the decision is made in the computer  28  whether a print size W×L in inches (″) and a print quantity Q have been manually selected. If both are selected, the computer  28  determines the paper width W in inches and the donor patch size W×L in inches corresponding to the selected print size W×L by going to a look-up table. Then, the print L×W, the paper W, the donor patch L×W, and the print quantity Q are stored in a memory in the computer  28 . 
     By way of example, a suitable look-up table in the computer  28  for the paper width W and the donor patch size W×L corresponding to the selected print size W×L is 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Selected Print 
                 Corresponding 
                 Corresponding Donor 
               
               
                   
                 W × L 
                 Paper W 
                 Patch W × L 
               
               
                   
                   
               
             
             
               
                   
                 5″ × 3.5″ 
                 5″ 
                 5.25″ × 4″ 
               
               
                   
                 5″ × 7′ 
                 5″ 
                 5.25″ × 7.5″ 
               
               
                   
                 6″ × 4″ 
                 6″ 
                 6.25″ × 4.5″ 
               
               
                   
                 6″ × 8″ 
                 6″ 
                 6.25″ × 8.5″ 
               
               
                   
                   
               
             
          
         
       
     
     Next (FIG.  2 ), the motors are energized to rotate the donor supply and take-up rolls  16  and  18 , the paper supply roll  20 , and the capstan roller  52 , to advance the donor web  14  off the rotated donor supply roll and to advance the paper web  22  off the rotated paper supply roll. 
     Next (FIG.  2 ), the donor roll mark sensor  24  senses the code marks  26  on the rotated donor supply roll  16  to determine the size, i.e. width W×length L in inches (″), of each donor patch on the donor web  14 , using the computer  28 , and the paper roll mark sensor  36  senses the code marks  38  on the rotated paper supply roll  20  to determine the paper width W in inches (″), using the computer. Then, the decision is made in the computer  28  whether the sensed donor patch L×W matches the stored (in the memory) donor patch L×W, and whether the sensed paper W matches the stored (in the memory) paper width W. If the answer is “no” for one or both inquiries, a “warning” is displayed and the cycle is discontinued—in which case the donor supply roll  16  and/or the paper supply roll  20  have to be replaced to provide a match or matches with the selected print L×W. If the answer is “yes” for both inquiries, a “match” is displayed in both cases and the cycle is continued. 
     Next (FIG.  3 ), the donor roll mark sensor  24  senses the code marks  26  on the rotated donor supply roll  16 , and the computer  28  uses this as timing information to first calculate the roll speed and then look up the corresponding roll diameter. Also, the donor roll mark sensor  24  senses the code marks  26  on the rotated donor supply roll  16  to determine the length L in inches (″), of each donor patch on the donor web  14 . This, coupled with the looked up roll diameter, allows the computer  28  to estimate the remaining number of donor patches available on the donor supply roll  16 . 
     At the same time or next (FIG.  3 ), the computer calculates the total number of donor patches required for the stored (in memory) print L×W and print quantity Q, i.e. 4×Q, and subtracts from 4×Q the patches counted as already used (if any, i.e.  1 - 3 ) to make Q, to determine the remaining (current) number of donor patches required to make Q. 
     Then (FIG.  3 ), the decision is made in the computer  28  whether the estimated remaining number of donor patches available on the donor supply roll  16  is not less than the determined remaining (current) number of donor patches required to make Q. If the former number is less than the latter number, a “warning” is displayed and the cycle is discontinued—in which case the short supply must be replenished. Otherwise, an “OK” is displayed and the cycle is continued. 
     Next (FIG.  4 ), the paper roll mark sensor  36  senses the code marks  38  on the rotated paper supply roll  20 , and the computer  28  uses this as timing information to first calculate the roll speed and then look up the corresponding roll diameter. This allows the computer  28  to estimate the remaining length of paper available on the paper supply roll  20 . 
     At the same time or next (FIG.  4 ), the computer calculates the total length of paper required for the stored (in memory) print L×W and print quantity Q, i.e. L×Q, and subtracts from L×Q the paper cuts counted as already done (if any) to make Q, to determine the remaining (current) length of paper required to make Q. 
     Then (FIG.  4 ), the decision is made in the computer  28  whether the estimated remaining length of paper available on the paper supply roll  20  is not less than the determined remaining (current) length of paper required to make Q. If the former number is less than the latter number, a “warning” is displayed and the cycle is discontinued—in which case the short supply must be replenished. Otherwise, an “OK” is displayed and the cycle is then completed. 
     The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. 
     PARTS LIST 
       10 . thermal printer 
       12 . cartridge 
       14 . donor web 
       16 . donor supply roll 
       18 . donor take-up roll 
       20 . paper supply roll 
       22 . paper (receiver) web 
       24 . donor roll mark sensor 
       26 . donor roll code marks 
       28 . programmed computer 
       30 . light emitter 
       32 . light-responsive detector 
       34 . print head 
       36 . paper roll mark sensor 
       38 . paper roll code marks 
       40 . paper cutter 
       42 . paper cut sensor 
       44 . paper roll removal sensor 
       46 . guide roller 
       48 . support roller 
       50 . pinch roller 
       52 . capstan roller 
       54 . guide roller 
       56 . circuit board