| 摘要 |
PROBLEM TO BE SOLVED: To detect the fault of the control element of a power supply circuit for a load (for example, temperature adjusting sub-heater and the fault of the load itself. SOLUTION: A power supply circuit has a plurality of loads SUBHY-SUBHK, power control elements TR2-TR5 for controlling the power of the loads, a power supply element TR1, which is connected to the common connecting terminal of load control elements, and controllers 1101-1109, which can independently control the power control elements and the power supply element. An abnormality detecting circuit has a resistor 1111 and capacitor 1112, which are connected between the above described common terminal and GND in series, and voltage dividing resistors 1113 and 1114, which observe the change in voltage across both ends of the capacitor. The voltage across both ends of the capacitor is monitored by a microcomputer through an Error terminal. By measuring the time change of the voltage in synchronization with the ON/OFF control of the power control element, the abnormality of the power control element and the abnormality of the load are detected, and the device is stopped at the time of abnormality. |
