| 摘要 |
<p>PURPOSE:To obtain a gradation control circuit for a thermal head capable of contributing to a high-speed printing. CONSTITUTION:A circuit is used for a thermal head provided with a plurality of heating elements 1a-1n for making a gradation printing on a recording medium by carrying a current to the respective heating elements 1a-1n by the number of times corresponding to gradation data. The gradation data is converted to gradatation bit signals each having a weight. Parallel-input shift registers 2a-2n of the same number as the heating elements 1a-1n are provided to receive the gradation bit signals. Operation circuits 8a-8n for converting the signal to a time in proportion to a gradation number stored in the respective shift registers and drivers for carrying a current to the corresponding heating elements 1a-1n by the number of times in response to the output time of the operation circuits 8a-8n are provided between the shift registers 2a-2n and the heating elements 1a-1n.</p> |
