Patent ID: 8328441
Filing Date: 2012-12-11
Classification: B41J,B65H,G01B

Abstract:
1. A thermal transfer printer for selectively transferring a meltable ink material carried on a tape to a substrate intended to receive ink for printing an image on the substrate, the printer comprising: two spool supports on which two spools of tape carrying meltable ink material may be mounted for rotation, with the tape being wound on the spools and with a span of tape being held in tension between the spools, with a region of unused tape to be made available for each image to be printed on the substrate; a print head positioned adjacent to the span of tape between the spools comprising a plurality of heating elements selectively energizable to transfer meltable ink material on the span of tape extending between the spools to the substrate when the heating elements are energized and are in contact with the tape, with the tape in contact with the substrate; a print head drive configured to selectively move the print head between an extended position adjacent the span of tape to transfer ink on the tape to the substrate to print an image and a retracted position spaced apart from the span of tape during each time period between each successive printing of adjacent images on the substrate for enabling transport of the tape and substrate relative to the print head to present the region of unused tape at the print head for printing a next image on the substrate, and for enabling transport of the tape independently of movement of the substrate so that the tape may be transported a distance different from a distance the substrate is to be moved for receiving the next image to be printed; a tension monitor configured to monitor a parameter indicative of tension in the span of tape held in tension between the spools of tape; a tape drive comprising two electrically energizable spool drives, one for each tape spool support, with each spool drive being configured to be selectively operable when energized to rotate its respective spool of tape one or more angular steps to a commanded angular position and being selectively operable when energized to hold its respective spool of tape at the commanded angular position against tension in the tape extending between the spools; each spool drive being coupled to its respective tape spool support by a respective drive coupling providing a fixed transmission ratio between rotary motion of the spool drive and rotary motion of the respective spool support; the tape drive further comprising a spool drive controller operatively associated with the spool drives and configured to control energization of one of the spool drives to rotate its respective spool of tape one or more angular steps in a tape transport direction for supplying tape in the tape transport direction past the print head and to control energization of the other spool drive to rotate its respective spool of tape one or more angular steps in the tape transport direction for taking up tape for transporting tape in the tape transport direction between the spools of tape; the spool drive controller further being configured to respond to the parameter indicative of tension in the span of tape indicating that tension in the tape is not at an acceptable level of tension by controlling energization of at least one of the spool drives to rotate its respective spool of tape one or more angular steps to add tape to the span of tape between the spools of tape to decrease tension in the tape extending between the spools of tape or to rotate its respective spool of tape one or more angular steps to subtract tape from the span of tape between the spools of tape to increase tension in the tape extending between the spools of tape; the spool drive controller further being configured to control energization of each of the spool drives to rotate its respective spool of tape one or more angular steps in the tape transport direction when the print head is in a retracted position to transport the tape relative to the print head to present the region of unused tape at the print head for printing the next image on the substrate and independently of movement of the substrate so that the tape may be transported a distance different from a distance the substrate is to be moved for receiving the next image to be printed; and a print head controller operatively associated with the heating elements and configured to control energization of the heating elements on the print head to be heated in a predetermined sequence for transferring meltable ink material from the region of unused tape to the substrate for printing an image onto the substrate.