| 摘要 |
<p>PURPOSE:To enable color printing with stable quality free of irregularities in color or density, by a method wherein the level of a detection signal indicative of the temperature of a thermal head is sampled and held at each time of starting a printing operation, and a driving voltage is controlled by providing a hold output with an offset according to each recording color. CONSTITUTION:A head-driving part 21 varies a driving output voltage according to a controlling voltage impressed on a controlling terminal 23. A thermistor 45 detects the temperature of the thermal head 5, and an output voltage from an inverting and amplifying circuit 40 is varied in proportion to variations of the temperature. In response to a command signal PRINT from a signal input terminal 34, a sampling and hold circuit 50 samples an output voltage from an inverting and amplifying circuit 50 according to the temperature detected by the thermistor 45 at the start of a printing period for one sheet of color image, and holds the sampled voltage until color printing of the single sheet of color image by sequential recording is completed. The hold output is supplied as a controlling voltage to the controlling terminal 23 through output transistors 61, 62.</p> |
