Method and apparatus for monitoring inking ribbon usage in a thermal

Abstract

A thermal transfer printer has a thermal print head with a number of thermal printing elements, operated by power electronics and controlled by a control unit to print an imprint on a medium by thermally transferring ink from an inking ribbon to the medium by energization of selected printing elements by the control unit. The inking ribbon and the medium are movably disposed between the print head and a counter roller with the inking ribbon being unwound from a supply reel and wound onto a take-up reel. In a method and apparatus for monitoring usage of the inking ribbon, the approaching end of the ribbon is identified, either by optically reading a mark on the inking ribbon or by monitoring the amount of ribbon on the supply reel or the take-up reel, and the contents of a memory, which may be a mechanical memory or an electronic memory, are altered to indicate the completion of one pass of the inking ribbon. The inking ribbon is then rewound from the take-up reel to the supply reel for re-use. Before beginning re-use of the inking ribbon, the memory is interrogated and the usage history information is obtained therefrom. The thermal energy with which subsequent impressions are made is then controlled by the control unit dependent on the degree of usage of the inking ribbon.