Patent ID: 8317421

Claim:
A thermal transfer printer for selectively transferring a meltable ink material carried on a tape to a substrate for printing an image on the substrate, the printer comprising: two spool supports for two spools of tape carrying ink material, with the tape being wound on the spools and with a span of tape being held in tension between the spools, the tape spools being carried on and driveable by respective spool supports with a region of unused tape to be made available for each image to be printed on the substrate; a print head positioned at the span of tape between the tape spools, the print head being mounted for selective movement between an extended position adjacent the span of tape between the spools and a retracted position spaced apart from the span of tape between the tape spools and comprising heating elements selectively energizable for transferring ink material on the span of tape between the tape spools to the substrate when the print head is moved into contact with the tape while the tape is in contact with the substrate to print an image, wherein the print head is moved to its retracted position during each time period between each successive printing of adjacent images on the substrate; a tape drive for selectively transporting tape between the spools of tape comprising two motors, each motor driving a spool of tape via its respective spool support; the tape drive further comprising a controller operatively associated with the motors and configured to control the energization of the motors to transport the tape in at least one direction between the spools, and to control energization of the motors to control a level of tension in the span of tape extending from one spool of tape to the other spool of tape; a monitor configured to monitor a parameter indicative of tension in the span of tape extending from one spool to the other spool of tape; a memory configured to store a plurality of tension correction data values, with the tension correction data values being associated with tape tension error values; the controller further being configured to: (a) respond to a first monitored level of tension in the span of tape indicating that tension in the tape is not at an acceptable target level of tension by generating a tape tension error value, (b) access the memory to retrieve a tension correction data value corresponding to the tape tension error value, (c) control energization of the motors based at least in part on the tension correction data value to adjust the tension in the tape; and (d) respond to a second monitored level of tension in the span of tape after said energization of the motors by modifying at least one tension correction data value stored in memory based at least in part on a comparison of the first monitored level of tension in the span of tape and the second monitored level of tension in the span of tape.