Patent ID: 7868563

Claim:
A light emitting device drive circuit for supplying a predetermined output current IL 0 to a light emitting device to drive the light emitting device, the light emitting device drive circuit comprising: a power conversion unit for receiving an input electric power and performing an electric power conversion on the input electric power in accordance with a control signal so as to generate the predetermined output current; a current detection unit for detecting an output current IL of the power conversion unit; a temperature detection unit for detecting a case internal temperature TD, which is an interior temperature of a case for accommodating the light emitting device drive circuit; a regulation unit being operable to: a) detect whether a temperature TL of the light emitting device has reached a first predetermined temperature TLmax based on TD, IL, and a temperature rise coefficient α in connection with IL, the temperature rise coefficient α being set in advance so that TL satisfies a relationship of TL=TD+α·IL, and b) generate a regulation signal for reducing IL 0 so that TL does not exceed TLmax in the event that a result of the detection indicates that TL has reached TLmax; and a control unit for controlling IL 0 in accordance with the regulation signal from the regulation unit.