Patent ID: 7459660

Claim:
A light emitting device calibration system for calibrating a light emitting device in an optical disc drive, the light emitting device calibration system comprising: a laser diode installed within the optical disc drive being the light emitting device to be calibrated; a microprocessor electrically coupled to the light emitting device for controlling power of the light emitting device by changing values of a drive signal, receiving a power indication signal corresponding to light emitted by the light emitting device, and determining a power relationship relating values of the drive signal to powers of the light emitting device according to the power indication signal for each of the values of the drive signal during a calibration mode; a light detector for detecting the light emitted by the light emitting device to generate an analog signal being directly proportional to the light emitted by the light emitting device; a signal calibration circuit having a predetermined reference voltage being coupled between the light detector and the microprocessor for generating the power indication signal having an inverse relationship with the analog signal such that when the analog signal is at the state of no light was emitted by the light emitting device, the power indication signal reaches at a predetermined maximum value, which is a function of the predetermined reference voltage; and a non-volatile memory for storing the power relationship determined by the microprocessor during the calibration mode, wherein the microprocessor uses said power relationship to control values of the drive signal according to desired powers of the light emitting device during a normal operation.