| 摘要 |
PURPOSE:To eliminate a persistent thermal effect and enable sufficient color development when a hand copy is used under temperature environment by shortening the pulse width of a strobe signal in accordance with an increase in detection temperature. CONSTITUTION:A variable clock signal from an oscillation circuit 18 is input to CPU 30 as an interruption signal whereby the pulse widths of strobe signals STR1, 2, 3, 4 from a control part 14 are controlled so that these pulse widths may coincide with the wavelength of the variable clock signal. That is, an increase in the temperature of a thermal head causes the oscillation frequency of the oscillation circuit 18 to increase, and subsequently the pulse width of the strobe signals STR1, 2, 3, 4 is reduced. The energization time of the thermal head is determined by the pulse width of the strobe signals. Therefore, the thermal head can always be maintained at a proper color developing temperature (sensitive paper) by decreasing the pulse width of the strobe signal according to an increase in the temperature of the thermal head. At the same time, power consumption can be minimized. |
