DRIVING CIRCUIT FOR THERMAL HEAD

摘要

PURPOSE:To ensure that it suffices to provide only one power source, by providing a constant-voltage circuit for generating a TTL power source by lowering the voltage of a power source for heating elements, in a thermal head driving circuit comprising a CMOS transistor. CONSTITUTION:Input gates 8-11 are provided with source power from the constant-voltage circuit 18 through a line 19, in a manner similar to that for a flip-flop 12, a latch circuit 13 and a gate 14. On the other hand, the threshold voltage for the gates 8-11 is 1/2 of the output voltage of the circuit 18. Therefore, the gates 8, 11 can be driven by a voltage on a TTL level by setting the output voltage of the circuit 18 to an appropriate value. Accordingly, since it suffices to provide only one power source without requiring two kinds of power sources, the driving circuit can be inexpensively constructed and can be easily fitted.