| 摘要 |
PURPOSE:To remarkably improve the reliability of the shortcircuit detection. CONSTITUTION:An average working voltage is monitored as a terminal voltage of a capasitor C2. When this voltage is below the first reference voltage (set with a resistance VR2), it is determined that a short circuit takes place between electrodes and thus, the output of a comparator Q2 becomes zero. As a result, the output of a gate N1 turns to 1 and a mid-working signal shows O. Then, a pulse oscillator OS is stopped, suspending the on/off action of the transistor, eventually making it open. Due to this, a high voltage source Vs is separatdd away between the electrodes and hence, with a low voltage source VL, a current flows in the route of the ground, work, an electrode phi, a diode D1, and the power source VL, so that the voltage at a point A exceeds the second reference voltage causing the comparator Q1 to turn to O. When the short circuit between P and W is got rid of, the cmparator Q1 turns to 1, and the signal CC turns to 1 to resume working. |
