Patent ID: 7952297

Claim:
A driving device driving a light-emitting element comprising: a first switch element to switch between applying or not applying to the light-emitting element a voltage directed to setting the light-emitting element in an ON state; a constant current control circuit to adjust a current flowing through the light-emitting element to a predetermined current value when the light-emitting element is in an ON state; and a first voltage conversion circuit including a second switch element to generate a direct-current voltage directed to setting the light-emitting element in an ON state from an alternating voltage in response to alternate switching of the second switch element between an ON state and an OFF state, wherein the constant current control circuit adjusts a current flowing through the light-emitting element to a predetermined current value when the light-emitting element is in an ON state by controlling an ON state and an OFF state of the second switch element, the driving device further comprising: a PWM control circuit to PWM-control an ON state and an OFF state of the first switch element, and a second voltage conversion circuit to convert the direct-current voltage to a predetermined voltage value to be applied to the PWM control circuit as a power supply voltage.