Zoran Corporation

Oak Technology, Inc.

Konishiroku Photo Industry Co., Ltd.

Verbatim Corporation

Sperry Rand Corporation

Excel Precision Corporation

Hubert Song

Hwee Chin Ong

John C Tsai

Mervyn L Hopson

Jean Chi

Akio Tanaka

Kam-Fung Yan

A system and method for controlling the position of an optical head of a disc during high speed recording. In one embodiment of the method, an optical disc has a plurality of tracks. The method comprises implementing CLV recording by said optical drive, determining a wobble signal based on address information contained in said plurality of tracks of said optical disk and determining a wobble clock signal based on said wobble signal. The method further comprises decoding said wobble clock signal by a decoder, said decoder to provide a sync clock signal to an encoder loop circuit, said sync clock signal based on said wobble clock signal generating an encoder clock signal using said encoder loop circuit. In addition, the method comprises comparing said sync clock signal to said encoder clock signal to provide a position command to position the optical head of said optical drive.

Method and apparatus for providing high speed recording on an optical medium

The present invention is a method and system to provide focus control in a multi-layer optical storage medium. The method comprises generating a beam of light and reflecting the beam of light off one of a first and a second optical layers on a disk. The reflected beam is detected and a servo signal is provided in response to the reflected beam. The light source is directed to move from a first position to a second position based on the servo signal, so as to focus the light source from one of the first or the second optical layer to another one of the first or the second optical layer.

Method and apparatus for providing focus control on a multi layer disc

The present invention is a method and system to provide adaptive control in an optical storage medium. The method comprises providing a beam of light, reflecting the beam of light off an optical disk and detecting the reflected beam. A value of the reflected beam is compared with a predetermined value, and an output signal is generated if the value of the reflected beam is greater than the predetermined value. A timing signal having a timing interval is generated and a control signal is generated if the output signal occurs over the timing interval. One of a current servo signal and a predetermined servo signal is provided in response to the control signal and a position of the light beam is controlled based on one of the current servo signal and the predetermined servo signal.

Method and apparatus for providing adaptive control of track servo

A center error signal is used to control the sled during fine search operations. The center error signal is used to synchronize the motion of a tracking actuator and a sled. A head is mounted on a sled in a disk drive. The sled is positioned by a sled motor and the head is positionally mounted on the sled. The head includes a lens that is optically coupled to a photo-sensor on the head. A tracking actuator positions the lens with respect to a track on the disk. A center error signal indicates a position of the lens with respect to a track on a disk. A tracks-to-jump signal specifies a predetermined number of tracks on the disk that the sled motor is to move. A modified tracks-to-jump signal is produced in response to the center error signal. The sled motor is controlled with the modified tracks-to-jump signal.

Method and apparatus for searching in a disk drive

To correct for run-out in an optical disk drive, a run-out reducing gain factor is selected. A run-out correction signal is produced by applying the run-out reducing gain factor to a center error signal. A servo drive signal is refined with the run-out correction signal to produce an adjusted servo drive signal. A tracking actuator is driven with the adjusted servo drive signal.

Method and apparatus for run-out correction in a disk drive

A method and apparatus provide positive lens position control when reading information from a disk storing data using a first and a second encoding format. When reading the data encoded in the second encoding format, the lens is maintained in a substantially stationary radial position with respect to the disk. When the data encoded in the second encoding format has an error, the lens position is changed to find a better position for reading the data.

Method and apparatus for reading data from a disk

A servotrack writing apparatus (10) for use on computer disk drive workpieces (12). A writer controller (58) puts the writing apparatus (10) in the role of master to direct the workpiece (12) as a slave to position its read-write head (36) and to write the servotracks. A tracking section (54) provides a modulated light beam (72) from which a reflected portion is detected by a bi-cell photo sensor (70) and processed in the writer controller (58) to determine the position of a thru-hole (40) or a detection region (42) in the actuator arm (24) of the workpiece (12). The writer controller (58) may use a lock-in amplifier (102, 104) for the processing the reflected portion of the light beam (72). A reference arm (44) is locked and moved in a synchronous relationship with the actuator arm (24). A measurement section (56) determines the position of the reference arm (44), and may include an interferometer system (122) having a differential head (128) and a differential target (124), to permit increased resolution and nulling of errors. The interferometer system (122) may also use multiple frequency techniques to further increase resolution.

Non-contact servotrack writing with phase sensitive detection

A servo system for a removable disk having twice the servo information per disk track. The disk is encoded such that the servo sectors on one surface of the disk are angularly off-set and are located half-way between the servo sectors on the other side of the disk. Once a desired track is located, the disk rotates and the system switches between heads on the two surfaces of the disk to alternately read the servo sectors on both sides of the disk. A demodulator, peak detector, sample/hold device stores the servo information from the previous two servo sectors which were read to produce a position error signal which controls the linear motor to keep the heads on the desired track.

Dual head servo system and method for a magnetic disk

A servo system for flexible magnetic disks such that the synchronization pulses do not have to be perfectly aligned. The disk is encoded such that consecutive servo tracks alternate between having a synchronization and an alternate synchronization mark. Four pulses represent a synchronization mark and two pulses represent an alternate synchronization mark. The alternate synchronization marks are off-set from the synchronization marks by a certain distance, such that they do not interfere with each other when a transducer head located between the servo tracks reads them. The disk drive system will read and identify the synchronization marks or alternate synchronization marks and start generating timing signals as appropriate. The servo bursts in the servo sector can then be read.

Method and apparatus for recording servo synchronization information

An optimum acceleration deceleration circuit for stepper motors wherein an error signal is fed to a rate limiter circuit which generates a speed output voltage. The speed output voltage is fed back to the rate limiter circuit through a non-linear gain amplifier and summing amps.

Optimum acceleration/deceleration circuit

A circuit for electronic damping of stepper motors capable of generating a pulse train for a wide range of steps such that the pulse train is contained within a period or periods of the resonant frequency of the rotor of the stepper motor to pre-condition for the delayed last step and the last pulse is delayed by a half-period of the resonant frequency. A frequency synthesizer generates a clock signal having a frequency which is an integer multiple of the natural frequency of the rotor of the stepper motor. The clock signal is fed through a gate to a digitally controllable counter which generates an output after one full period of the stepper motor rotor's natural frequency. The output of the digitally controllable counter closes the gate to block the clock signal and triggers a delay circuit which generates the last pulse after a half-period of the natural frequency of the rotor of the stepper motor.

Digitally controllable electronic damper

A phase lock system for locking the output pulses of a motor driven tachometer in phase with reference pulses that recur at a prescribed reference frequency. A phase/frequency detector operates in a frequency mode when there is a frequency difference between the output pulses and the reference pulses so as to generate an error signal indicative of the frequency difference and a saturating amplifier coupled between the phase/frequency detector and the tachometer motor responds to the error signal to provide maximum drive power to the motor so as to vary the tachometer and drive the output pulse frequency toward the reference pulse frequency at a maximum rate. When frequency equality is achieved, the phase/frequency detector operates in a phase mode in which the phase error between the output pulses and the reference pulses is measured at a time when the system is still in saturation because of its high gain. A phase error rate signal is derived from another phase detector responsive to the phase error to produce a counter torque pulse having a duration related to the phase error rate. Such counter torque pulse is applied momentarily to override the effect of the phase error signal so as to drive the saturating amplifier briefly into saturation in the opposite direction as phase lock is approached whereby the motor is slowed as it approaches phase lock in order to assure phase lock without oscillation upon entry into the linear region of the amplifier.

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Sunnyvale, CA, United States of America

Hubert Song