| 摘要 |
PURPOSE:To print with a fixed density irrespectively of whether a head is driven continuously or discontinuously, by a method wherein a printing head is provided with a temperature-controlling resistor, and the resistor is controlled by pulses to maintain the head at a fixed temperature. CONSTITUTION:For example, when discontinuously driving the thermal head 1, the head 1 tends to be cooled. This condition is detected by a temperature sensor 3, and a signal is inputted into a strobe signal forming circuit 7 through a resistance bridge circuit 4, a linear amplifying circuit 5 and an A-D converter 6. In response to an output signal STR1 from the circuit 7, a transistor 10 is turned ON or OFF through an AND gate 9 by a pulse signal STR from a reference pulse generating circuit 8, whereby the temperature-controlling resistor 11 embedded in the head 1 is driven to control the temperature of the head 1 to a fixed temperature. Accordingly, the density of images printed by heating elements 2 can be made to fixed. |
