| 摘要 |
<p>PURPOSE:To prevent destruction of a drive circuit and a resistance heater by providing a voltage sequence circuit beteen power supply and receiving circuits so as to control an applied voltage of a power receiving and supply circuit so as to absorb a surge voltage. CONSTITUTION:A voltage sequence circuit comprising a reference voltage generating circuit consisting of dummy resistors 7-9 generating a comparison voltage, a comparator 10 inputting a comparison voltage to an inverting input and inputting a reference voltage to a non-inverting input respectively and comparing the voltages, and a voltage relay 11 activated by the output of the comparator 10 is formed in the midpoint of a grounding line 6 connecting a power supply 1 and a drive circuit 2. When the relay 11 is opened, a voltage of the power supply 1 is divided by resistors 12, 13, a voltage lower than a prescribed voltage is applied to the circuit 2 and a prescribed voltage is applied at closing state. In this case, a comparison voltage is generated across the resistor 7 and until the relay 11 is closed, there is a time delay, then even if a surge voltage is applied to the ground line, the relay 11 is not closed, the surge voltage is absorbed so as to prevent destruction of the resistance heater and the circuit 2.</p> |
