| 摘要 |
PURPOSE:To make it possible to enhance the efficiency of a power source circuit, by mounting a current limiting resistor for limiting the current supplied to the boosting stabilization circuit provided to a switching circuit, and increasing and decreasing the resistance value of said resistor by the printing signal supplied to a printing head. CONSTITUTION:A current limiting resistor R6 is set to a large value and a bypass resistor R8 is set to a small value. When there is no printing signal from a microcomputer, a resistance increasing and decreasing transistor Q7 is turned OFF and the bypass resistor R8 is removed from a circuit and a current is suppressed to a reduced value by the resistor R6. When there is the printing signal, the transistor Q7 is turned ON and the base current of a transistor Q6 increases and a large current required in printing is supplied to a boosting stabilization circuit C. Therefore, power consumption is reduced at an unnecessary time and a large current is supplied at a necessary time to enable the enhancement of the efficiency of a power source circuit. |
