| 摘要 |
PURPOSE:To secure a simple detection for the fault of temperature control, by installing a timer that is set and reset by the heater on and off of the temperature control output plus a timer that is set and reset by the heater off and on, respectively. CONSTITUTION:The temperature control 2 having a temperature sensor 1 generates the control output A produced by a repetition of heater on and off, and controls the heater 6 via the driver 5. The signal A is put into the set terminal of the 1st fault detecting timer 3, the reset terminal of the 2nd fault detecting timer 4 and the inverer 7, respectively. The output signal of the inverter 7 is put into the set terminal of the timer 4 and the reset terminal of the timer 3; and the outputs of the timers 3 and 4 are sent to the terminal 9 via the OR gate 8 in the form of the fault detection output. The timer time of each of the timers 3 and 4 is set longer than the maximum time interval between the heater on and off of the signal A. As a result, the defects of the sensor 1 and controller 2 as well as the faults of both high and low temperature controls of the heater 6 due to a disconnection or the like can be detected in a simple way. |
