| 摘要 |
PURPOSE:To shorten the time required in the detection of disconnection, by providing the first resistor connected between the output terminal and reversal input terminal of an operation amplifier through the first switch, the second resistor connected between the reversal input terminal of the operational amplifier and an earth point and a series circuit consisting of the third resistor connecting in parallel to the first switch and the second switch. CONSTITUTION:When the first switch 22 is turned OFF and the second switch 26 is turned ON, a usual mode is changed to a disconnection check mode, but the voltage applied to a condenser 27 becomes the same to that at the time of the usual mode and, even when the mode changes, the voltage of the condenser 27 does not change. Therefore, the output of a differential amplifier 32 immediately becomes a stable state and the usual mode is changed to the disconnection check mode to immediately allow switching transistors 30,... to successively take switching operation and a current is supplied to heat generators 29,... to make it possible to start the checking of the disconnection of the heat generators. |
