The thermal transfer printer of the present invention prevents slackening of recording paper by exerting a braking force upon a recording paper roll to give a back tension to the recording paper when one of the colors of an ink sheet coated with inks of a plurality of colors is thermal-transfer-printed....http://www.google.com.tw/patents/US4755833?utm_source=gb-gplus-share專利 US4755833 - Thermal transfer printer
