Mediatek Corporation

Mediatek Incorporation

Hsu-Feng Ho

Shun-Yung Wang

Shang-Wei Wu

Chao-Hsin Tseng

Tse-Hsiang Hsu

Shih-Jung Chiu

Chih-Hsien Kao

Kuang-jung Chang

Yung-Chih Li

Shih-Hao Ke

Jia-Hao Lin

Bor-Cheng Shih

A method for detecting whether vertical deviation of an optical disc occurs is provided. First, before a pickup head is successfully focused on the optical disc, a pickup head is actuated based on an input control signal so as to generate a focus error signal with a plurality of S-curves. Then, a plurality of zero crossing points of the S-curves in the focus error signal is identified and a plurality of input control values respectively corresponding to the zero crossing points is obtained. A variation of the input control values is then calculated. Whether vertical deviation of the optical disc occurs can be determined according to the variation of the input control values.

Method of vertical deviation disc detection

A device and method for reducing power consumption of an optical drive are proposed. The present invention samples a carrier control signal and then compares the samples of the signals with predetermined threshold signals. According to the comparison result, the present invention produces at least one diphase excitation control signal. The diphase excitation control signal comprises at least one impulse signal, and a negative edge of the impulse signal is adjusted to a predetermined level during the period of the diphase excitation control signal. The present invention reduces the time for outputting the control signals and greatly reduces the power consumption of the optical drive thereby.

Device for reducing power consumption of optical drive and method for the same

A device and method for reducing power consumption of an optical drive are proposed. The present invention samples a carrier control signal and then compares the samples of the signals with predetermined threshold signals. According to the comparison result, the present invention increases or decreases an output signal index. The variation of the output signal index is used to control phases of diphase excitation control signals so as to control the rotation direction of a motor or make it stop. The present invention need not output the diphase excitation control signals continuously. It only needs to output a predetermined number of the diphase excitation control signals after the output signal index is increased or decreased. Hence, the present invention reduces the time for outputting the control signals and greatly reduces the power consumption of the optical drive thereby.

An apparatus having switchable servo gains and offsets for an optical disk drive adjusts its gains and offsets through the coupling of a servo signal and a switch with several changeable paths. The servo signals are either designated to undergo signal reduction with respect to a first offset, through the switch and then be output after a first gain unit performed proportional conversion, or designated to undergo signal reduction with respect to a second offset and then be output after a second gain unit performed proportional conversion. The switch is switched on/off in the light of the working status of the pick-up head, for example, seeking or tracking, at a data area or at a blank area, and at a groove area or at a land area, so as to choose different offsets and gains to have the conversion of the servo signals.

Apparatus having switchable servo gains and offsets for optical disk drive and method thereof

The invention provides an adaptive brake force setting system. Every time when a pickup head with a predetermined mass crosses a plurality of recording tracks in an optical recording media, the system is used for selling brake force to make the pickup head stop from a predetermined initial brake position to a target recording track. The system comprises a detecting module and an estimating module. The detecting module is for detecting a final velocity and an acceleration of the pickup head when the pickup head arrives at the initial brake position. The estimating module is for, according to the final velocity and the acceleration, using a predetermined brake force estimating process to estimate the brake force exerted on the pickup head at each time for making the pickup head stop to the target recording track in a predetermined braking time. Therefore, the pickup head stop exactly to the target-recording track.

Adaptive brake force setting system in an optical recording device

A method is provided to detect whether vertical deviation occurs as an optical disc spins in an optical disc player having a pickup head pre-installed in a balanced position at a focal distance. When moving towards and away from the balanced position, the pickup head generates a focus error signal with an S-curve. According to an input control signal, a focus actuator actuates the pickup head to keep it substantially at the focal distance. When the pickup head is not focused, the waveform of the input control signal is designed to actuate the pickup head back and forth within a predetermined range to generate the focus error signal with S-curves. Zero crossing points of S-curves are identified and input control values in the input control signal are obtained accordingly. The variation of the input control values is calculated, and whether vertical deviation occurs is determined by a predetermined procedure.

A device for correcting optical path deviation of an optical pickup in an optical recording system includes a push-pull signal generator for generating a push-pull signal while the optical pickup is operated in a focusing and non-track-locking state, a low-pass filter module for generating a direct current (DC) level error signal from the push-pull signal, and a combiner for generating a calibrating servo signal based on the DC level error signal and a servo control signal from a servo controller of the optical recording system and for applying the calibrating servo signal to a servo mechanism of the optical recording system so as to adjust position of an objective lens of the optical pickup in order to maintain the DC level of the push-pull signal at an ideal level.

Method and device for correcting optical path deviation of an optical pickup in an optical recording system

A control circuit for an optical disk drive includes a frequency detector, a phase detector, a low pass filter, a voltage-controlled oscillator (VCO), and a controller. The frequency detector and the phase detector both receive an eight-to-fourteen modulation (EFM) signal and a data phase-locked loop (DPLL) signal. The controller can calculate a target frequency and control the VCO to output the DPLL signal according to the target frequency. During a non-seek mode, the VCO outputs the DPLL signal according to output of the frequency detector, phase detector, and low pass filter. During a seek mode or when spindle speed of the optical disk drive changes, the VCO outputs the DPLL signal according to the target frequency. The controller further outputs charge pump currents for the frequency detector and the phase detector and sets an RF equalizer signal and a differential phase detector (DPD) equalizer signal according to the target frequency.

Apparatus for controlling an optical disk drive by calculating a target frequency of a DPLL signal

An apparatus having switchable servo gains and offsets for an optical disk drive adjusts its gains and offsets through the coupling of a servo signal and a switch with several changeable paths. The servo signals are either designated to undergo signal reduction with respect to a first offset through the switch and then be output after a first gain unit performed proportional conversion, or designated to undergo signal reduction with respect to a second offset and then be output after a second gain unit performed proportional conversion. The switch is switched on/off in the light of the working status of the pick-up head, for example, seeking or tracking, at a data area or at a blank area, and at a groove area or at a land area, so as to choose different offsets and gains to have the conversion of the servo signals.

A method for measuring a tilt angle of a pickup head. The method includes the steps of: moving the pickup head to a track to be measured; radiating a laser beam with a constant power; defining a proper range of tilt control values; controlling the tilt angle of the pickup head according to the range of tilt control values, acquiring a RF signal corresponding to each tilt control value, and storing an associated value of a associated signal; detecting the maximum among the stored associated values; selecting and storing the tilt control value corresponding to the maximum as the optimum tilt control value for the track if there is a maximum; and modifying the range of tilt control values and executing the previous steps if there is no maximum. The so-called associated signal includes a tracking error signal, a reading/writing RF signal, an S-curve signal, or the RF signal.

Method for measuring a tilt control value of a pickup head in an optical disk drive

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.

Method for detecting eccentricity of an optical disc, and optical disc drive that performs the method

A track locking method and an apparatus thereof enable an optical disk drive to rapidly and stably read data recorded on a target track from a seeking mode to a track locking mode. An optical pick-up head can switch from the on-track interval of a target track to an adjoining off track period only if the tracking servo control system memorizes the last-minute level of the tracking servo output signal of the on-track interval and keeps the tracking servo output signal at the level, so as to generate a pulling force whereby the optical pick-up head is moved back to the on-track interval from the off-track interval.

Track locking method for optical disk drive and apparatus

A phase difference between a first periodic signal, and a sample signal corresponding to a second periodic signal and having a predetermined signal resolution M is calculated in a phase comparing method. The sample signal is obtained by sampling the second periodic signal at a sampling frequency ffor one signal cycle of the second periodic signal when a frequency of the second periodic signal is not greater than an allowable sampling signal frequency fequal to f/M or by conducting at least one of sampling the second periodic signal at ffor more than one signal cycle of the second periodic signal, and generating interpolated values for the sample signal after sampling the second periodic signal at fin accordance with whether or not M/N yields a remainder and whether or not N is a prime number when the frequency of the second periodic signal is greater than and is N times f.

Phase comparing method and apparatus in which a sampled periodic signal has a predetermined resolution

A compensation method for detecting the seeking speed of an optical disk drive involves the following steps. First, a TE signal is converted into a TEZC signal, or an RFRP signal is converted into an RFZC signal. Then, take the average of the respective pulse widths of an upper waveform and an adjoining lower waveform of the TEZC signal or the RFZC signal to acquire the recovered TEZC signal or RFZC signal wherein both the upper waveform and the lower waveform are decided by a slice levels.

Growing community of inventors

Taipei, Taiwan

Hsu-Feng Ho