| 摘要 |
<p>PURPOSE:To improve safeness with simple constitution and to form an integrated circuit, by stopping the reverse bias of an FET at the opening of a heat- sensitive means and short-circuiting a pulse signal to stop the operation of a switching element for controlling electric conduction to a heater. CONSTITUTION:At the normal time, current is made flow into a closed circuit consisting of an AC power supply 1, a resistor 29, a capacitor 28, a diode 27, a resistor 26, a thermistor 25, and the AC power supply 1 and reverse bias is applied between the gate and source of an FET24, so that the FET24 is kept at off-status. When temperature rises and the thermistor 25, etc. are opened, no current is made flow into the closed circuit, so that the reverse bias to the FET24 is stopped. Consequently, the FET24 is connected and the gate signal of a thyristor 3 is by-passed by the FET24 and is not supplied to the thyristor 3, so that the connection of the thyristor 3 is stopped and no power is supplied to a heater 2.</p> |
