Gradation control circuit of line thermal printer

Abstract

Abstract A gradation modulating apparatus is provided in a line thermal printer having a plurality of resistive elements (B₀-B n ) arranged linearly widthwise of a medium (P) for printing gradated dots line-sequentially according to gradation image data. A memory (2) is provided for storing individual weight data (L₀-L₁₅) representative of energy generation rates of respective resistive elements (B₀-B n ), in corresponding addresses. An address generator (1) is responsive to serial input of the gradation image data for generating an addressing signal effective to read out the stored individual weight data (L₀-L₁₅). A modulator (3) is receptive of the inputted gradation data and the read weight data in synchronization with each other for producing modulated gradation image data according to the weight data. A latching circuit (4) is connected for latching the modulated gradation image data line-sequentially. A driver (5) is connected for applying driving signals regulated according to the latched modulated gradation image data to the resistive elements (B₀-B n ), to enable the same to print dots having substantially the same print density for a given gradation level defined by the input gradation data.

Inventors

• 👤 Toshiharu Aoyagi

Bibliographic Details