Abstract
Having developed a prototype of a metallic-base thin-film thermal head, we compared its density irregularity characteristics in the main scanning direction, with those of the alumina-base thermal head, and found the metallic-base to be superior in terms of uniformity in transferred ink density.
By using thermal analysis of the finite element method, we found that the following factors are predominantly responsible:
(1) Distribution of the equivalent air gap determined by the contact between thermal head surface and ink sheet.
(2) Nonuniform distribution of the common resistance due to the fact that the heat elements closer to the middle have higher common electrode resistance.
The reasons the metallic-base type is superior are that, it ensuring a uniform distribution of the equivalent air gap layer, and also because the base itself can serve as a common electrode, resulting in uniform common resistance.
