Patent ID: 7274151

Claim:
A drive device, comprising: a light emitting element; a constant current source; and a light emission control switch, wherein the light emitting element, the constant current source and the light emission control switch are connected in series between a first potential and a second potential whose electrical potential is lower than the first potential in any one order of (1) the light emitting element, the constant current source, and the light emission control switch, (2) the light emitting element, the light emission control switch, and the constant current source, (3) the constant current source, the light emitting element, and the light emission control switch, and wherein at least one current regulating resistor is connected in parallel to the light emitting element for regulating a current value flowing in the light emitting element, and wherein the light emitting element has a diode characteristic and a reverse bias applying switch is provided in an anode side of the light emitting element so that the anode side of the light emitting element is switched and connected to a third potential whose electrical potential is lower than that of the first potential.