Patent ID: 7599412

Claim:
A method for controlling a supply voltage of a light source, the light source being arranged in one of a first circuit configuration having an associated first reference voltage level and a second circuit configuration having an associated second reference voltage level, the method comprising the steps of: gradually changing the supply voltage into a direction of the first reference voltage level; measuring light emission of the light source while gradually changing the supply voltage into the direction of the first reference voltage level; if no light emission is measured during the measuring step, determining that the light source is arranged in the first circuit configuration and controlling the supply voltage after the first reference voltage level has been reached; and if a light emission is measured during the measuring step, determining that the light source is arranged in the second circuit configuration and gradually changing the supply voltage into a direction of the second reference voltage level and controlling the supply voltage after the second reference voltage level has been reached and the first circuit configuration includes a PNP type circuit configuration and the second circuit configuration includes an NPN type circuit configuration.