Thermal line printer with staggered head segments and overlap

Abstract

A thermal line printer line-sequentially prints dots on a recording medium in horizontal and vertical directions according to bit data. A line thermal head includes a plurality of linear head segments arranged in a pair of parallel rows along the horizontal direction in staggered relation to each other such that the head segments partly overlaps through different relative displacements with each other between the rows. Each of the head segments has a plurality of heating elements disposed linearly along the segment, and effective to print dot according to image bit data and ineffective to print dot according to blank bit data. A feeding device line-sequentially feeds a recording medium relative to the line thermal head in the vertical direction. A designating circuit operates according to the different relative displacements for designating effective and ineffective sections adjacently with each other to the respective head segments such that the designated effective sections are successively connected to each other in the horizontal direction without irregular overlapping and spacing. An assigning circuit operates during each line-sequential printing for assigning image bit data to heating elements within the effective sections and blank bit data to heating elements within the ineffective sections to thereby effect regular dot printing along each line.