Patent ID: 7005827

Claim:
A starting circuit for a single-phase induction motor, included in a motor driver including an auxiliary coil driving the motor at the startup of the motor and a main coil driving the motor in a steady-state drive operation, the starting circuit comprising: a motor starting positive characteristic thermistor and a triac arranged in a series connection that are connected in series with the auxiliary coil; and a triac control positive characteristic thermistor, connected in parallel with the motor starting positive characteristic thermistor, and including one terminal thereof connected to a gate of the triac; wherein the triac control positive characteristic thermistor has a volume in the range of about 4.5 mm 3 to about 30 mm 3 ; the relationship of (√2×V×sin 45°)/R≧I is maintained with the triac control positive characteristic thermistor within an operating temperature range, where V represents a root-mean-square value of a power source voltage, R represents a resistance of the triac control positive characteristic thermistor, and I represents a gate turn-on current of the triac; and the gate turn-on current I at an operating temperature of about 25° C. is about 20 mA or less.