Mediatek Corporation

Mediatek Incorporation

Yung-Chih Li

Hsueh-Kun Liao

Ching-Chuan Hsu

Hsu-Feng Ho

Hsin-Chung Yeh

Jin-Chuan Hsu

Kuang-jung Chang

Chao-Hsing Tseng

A laser power control unit used for controlling the laser power of an optical pick-up unit (OPU) is provided. The laser power control unit includes: at least one analog-to-digital converter (ADC) electrically coupled to the OPU for transferring a front photodiode output signal into a digital feedback signal; and at least one digital control circuit electrically coupled to the ADC for generating a power control signal and outputting the power control signal to the OPU in order to control the laser power of the OPU. The digital control circuit has a compensation circuit used for generating a compensation value according to a difference between the digital feedback signal and a digital target feedback signal so as to adjust the power control signal. The front photodiode output signal corresponds to the laser power of the OPU.

Laser power control unit and method for performing auto power control

A device for canceling a land-groove offset component of a focusing error signal in an optical storage system includes first and second circuits, and an adder. The first circuit processes a radio (or wobble) frequency ripple signal to obtain a first processed signal that is multiplied by a first gain value (G) so as to result in a first signal. The second circuit processes a tracking error signal to obtain a second processed signal that is multiplied by a second gain value (G) so as to result in a second signal. The adder is coupled to the first and second circuits, and adds the first and second signals to produce a compensative land-groove offset component that is to be fed into a focusing device of the optical storage system so as to enable the focusing device to cancel out the land-groove offset component of the focusing error signal.

Method and device for canceling a land-groove offset component of a focusing error signal in an optical storage system

A laser power controller for performing an auto power control to control the laser power of an optical pick-up unit (OPU) includes: a sample/hold circuit used for sampling and holding a front photodiode output signal to generate an analog feedback signal; an analog-to-digital converter (ADC) electrically coupled to the sample/hold circuit for transferring the analog feedback signal into a digital feedback signal; and a digital control circuit electrically coupled to the ADC for generating a power control signal and outputting the power control signal to the OPU in order to control the laser power of the OPU. The front photodiode output signal corresponds to the laser power of the OPU.

Laser power controller and method for performing auto power control

An optical disc drive includes a spindle motor and a computer program. The spindle motor is adapted for rotating an optical disc. The computer program configures the optical disc drive to perform consecutive steps of a method for detecting eccentricity of the optical disc, including: a) while the optical disc drive operates under focused and track-locked conditions, controlling the spindle motor to rotate the optical disc at a specified rotation speed; b) measuring an eccentricity value of the optical disc being rotated by the spindle motor; and c) comparing the eccentricity value measured in step b) with a reference value to determine extent of eccentricity of the optical disc.

Growing community of inventors

Taipei Hsien, Taiwan

Yung-Chih Li