| 摘要 |
PURPOSE:To simplify a driver checking circuit and to improve the detecting sensitivity by providing a detecting transistor instead of a comparator which forms the driver checking circuit. CONSTITUTION:A driver checking circuit 1' which detects the malfunction of any of a plurality of drive coils L1-Ln is provided commonly at the coils. A detecting transistor Tr1 is provided instead of the conventional comparator in the checking circuit 1', a resistor R2 is provided between the emitter and the base of the transistor, and the resistance value is set to a value which satisfies (V-Vc)XR2/(R1+R2)>=0.7, where r1 is the resistance values of resistors R11- R1n, V is supplied voltage, and Vc is the voltage at the connecting point of the drive coil to drive element. When the drivers Q1-Qn are damaged or the drive coil is shortcircuited, the base voltage of the transistor Tr is reduced through the resistors R11-R1n, the transistor is conducted, and an output voltage is generated at the resistor R2. |
