Electromagnetic coil drive device

1. An electromagnetic coil drive device, comprising:

a semiconductor switch connected in series with an electromagnetic coil for controlling a current supplied to the coil;

a capacitor;

a comparator for comparing a voltage to charge and discharge the capacitor with two different voltages, for generating a signal to operate on-off of the semiconductor switch in accordance with a result of a comparison;

a first charging circuit to charge the capacitor based on a voltage applied to the coil; and

a discharging circuit to discharge the capacitor;

wherein the first charging circuit has a first resistor and at least one compensating circuit connected in parallel with the first resistor, and

the compensating circuit includes:

a first compensating circuit in which a second resistor and a first Zener diode are connected in series, and

a second compensating circuit in which a third resistor and a second Zener diode are connected in series; and

the first Zener diode and the second Zener diode have different Zener voltages.

2. An electromagnetic coil drive device according to claim 1 , further comprising a second charging circuit to charge the capacitor based on a stabilized voltage.

3. An electromagnetic coil drive device according to claim 1 , wherein the first charging circuit further comprises a temperature sensing resistor element connected in series with the first resistor.

4. An electromagnetic coil drive device according to claim 3 , wherein the temperature sensing resistor element has a positive temperature coefficient.