| 摘要 |
<p>A drive circuit for a thermal printer which prints characters on a printing medium by selectively applying current to heat generating elements (60) comprises a current application control circuit (63) controlling the application of current to the heat generating elements, and a time control circuit (56) capable of varying the period of time for which the current application control circuit is rendered operative. The time control circuit comprises a charging circuit which is a series circuit having a constant voltage device (44), a resistor (48) and a capacitor (50), a discharging circuit (51) connected in parallel to the charging circuit, and a switching circuit (53) which is rendered conductive and non-conductive selectively in dependence upon the charge on the capacitor. The charging circuit is connected between the terminals of a power supply (41) such as a battery from which current is provided to the heat generating elements.</p> |
