A thermal ribbon cassette includes a take-up spool and a supply spool rotatively mounted in the cassette housing. The spools are aligned to respective aperture in the rear wall of the housing. The housing has a print head opening located between the supply spool and the take-up spool dividing the cassette...http://www.google.com.au/patents/US5318368?utm_source=gb-gplus-sharePatent US5318368 - Thermal transfer ribbon having ribbon follower
