Study on a Thin Film Thermal Print Head for High Definition Multi-Level-Tone Color Imaging Use

Abstract

We studied a 600 dpi high definition thermal print head. Fast thermal response, thermal resistance, uniform contact pressure on print media, and micro process are necessary to achieve 600 dpi high definition thermal transfer print. Therefore, we examined a new structure of a low thermal diffusivity layer on a high thermal diffusivity substrate, and optimum new design of the head shape. As a result, we could drive a 600 dpi thermal print head at high speed and high duty. We studied thermal print head to achieve multi-level tone in thermal transfer printing, which required appropriate heat control of heating elements on the head and varying the amount of resin ink melted by the energized head edge, that is, varying dot diameter as needed. After a series of examination, we came to the conclusion that head form especially the part between a heating elements and head edge is deeply related to the property of the tone. This meant that optimization of the head form was the key to the solution. Thus we have attained multi-level-tone printing by varying dot diameter in 16 levels with the enhanced print head.