Heater device and oscillation apparatus
A heater device includes a temperature detector, a heater control circuit, a heater, a voltage supply path, and an overheat prevention circuit. The overheat prevention circuit includes a positive-temperature-coefficient thermistor and a pull-up resistor. The positive-temperature-coefficient thermist...
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Format: | Patent |
Sprache: | eng |
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Zusammenfassung: | A heater device includes a temperature detector, a heater control circuit, a heater, a voltage supply path, and an overheat prevention circuit. The overheat prevention circuit includes a positive-temperature-coefficient thermistor and a pull-up resistor. The positive-temperature-coefficient thermistor is interposed on the voltage supply path in a position for being heated by the heater. The pull-up resistor that includes: one end connected between the heater and the positive-temperature-coefficient thermistor, and another end connected to a direct current power source. The control voltage to be applied to the heater is restricted to a voltage at a connection point between the positive-temperature-coefficient thermistor and the pull-up resistor when the control voltage from the heater control circuit is abnormally decreased. |
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