| 摘要 |
PURPOSE:To enable the control of gradation recording by a simple constitution, by providing a means performing the control of a pulse width to obtain a gradation printing pulse and a means adding a pulse within a range generating no color forming recording of a thermal recording material to a gradation printing pulse to obtain the printing pulse of a thermal head. CONSTITUTION:When the cycle of the output (b) of a clock signal generating circuit 3 is set to T, the output (a) of a gradation recording signal generation part 2 is inputted to a recording signal adding part 6 where a pulse having a width within a range allowing a recording material to form no color is added to obtain output (d). When a pulse width is 18T, a power source 5 is regulated to lower the voltage thereof so that recording density comes to saturated density Dmax. Whereupon, in the relation between a recording signal pulse width and recording density, is gradations are taken between Do-Dmax with respect to the 16-stage change in the pulse width of 3T-18T. That is, by adding a pulse with a definite width to the recording signal having received the modulation of a pulse width, recording having a number of gradations corresponding to the number of stages in the modulation of the pulse width for gradation recording is enabled. |
