US 7,459,660 B2Granted

System and method for calibrating light emitting device

AssigneeMediatek Incorporation

InventorsKun-Yi Chan, Shang-Pin Sun

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Abstract

A light emitting device calibration system includes a device under test including a light emitting device to be calibrated and a microprocessor electrically coupled to the light emitting device. A light detector is coupled to the device under test. During a calibration mode, the microprocessor controls power of the light emitting device by changing values of a drive signal to the light emitting device, receives a power indication corresponding to light emitted by the light emitting device, and determines a power relationship relating values of the drive signal to powers of the light emitting device according to a power indication for each of a plurality of values of the drive signal. The light detector coupled to the device under test detects the light emitted by the light emitting device to generate the power indication corresponding to the light emitted by the light emitting device.

Claims44

Dependent claims

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.

3 more elements

A method of calibrating a light emitting device in an optical disc drive, the method comprising:

providing a laser diode installed within the optical disc drive being the light emitting device to be calibrated;
controlling power of the light emitting device by changing values of a drive signal to the light emitting device during a calibration mode;
receiving a power indication signal corresponding to light emitted by the light emitting device;
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;
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;
providing a predetermined reference voltage;
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
storing the power relationship determined during the calibration mode for controlling values of the drive signal according to desired powers of the light emitting device in a normal operation mode.

6 more elements

A light emitting device calibration system for calibrating a light emitting device in an optical disc drive, the light emitting device calibration srtern 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 rower 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;
a signal calibration circuit having a predetermined reference voltage for generating the power indication signal according to the analog signal and 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.

4 more elements

A method of calibrating a light emitting device in an optical disc drive, the method comprising:

providing a laser diode installed within the optical disc drive being the light emitting device to be calibrated;
controlling power of the light emitting device by changing values of a drive signal to the light emitting device during a calibration mode;
receiving a power indication signal corresponding to light emitted by the light emitting device;
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;
detecting the light emitted by the light emitting device to generate an analog signal;
providing a predetermined reference voltage;
generating the power indication signal according to the analog signal and the predetermined reference voltage;
and
storing the power relationship determined during the calibration mode in a non-volatile memory for controlling values of the drive signal according to desired powers of the light emitting device in a nonnal operation mode.

6 more elements

Dependencies are inferred from the claim text.