Zen Research N.v.

Zen Research (Ireland), Ltd.

Jacob Finkelstein

Amir Alon

Michael Naor

Itzhak Katz

Shlomo Shapira

Methods and apparatus are provided for detecting and correcting magnification errors while simultaneously reading or writing multiple data tracks with a multi-beam optical disk drive. An optical head for the optical disk drive includes a plurality of laser diodes that generate multiple light beams for reading from or writing to the optical disk, means for detecting a magnification error, and means for compensating for the magnification error to align the multiple light beams with multiple data tracks. A number of opto-mechanical systems are provided for correcting the magnification errors in the beams.

Methods and apparatus for detecting and correcting magnification error in a multi-beam optical disk drive

Methods and apparatus are provided for synchronously reading data from multiple tracks of an optical disk using multiple illumination beams. Circuitry is provided for use with a photodetector array to read and buffer data in parallel from the multiple adjacent tracks, while asynchronously providing processed data to a host processor. Circuitry is further provided for concurrently processing the signals read from the multiple data tracks to recover the data stored in the tracks.

Methods and apparatus for concurrently processing data from multiple tracks of an optical storage medium

Methods and apparatus are provided for synchronously reading data from multiple tracks of an optical disk using multiple illumination beams. Circuitry is provided for use with a photodetector array to read and buffer data in parallel from the multiple adjacent tracks, while asynchronously providing processed data to a host processor. Circuitry is further provided for correcting phase errors resulting from variations in the linear velocity of the tracks being read, depending upon the radial position of the tracks.

Methods and apparatus for simultaneously reading multiple tracks of an

Methods and apparatus are provided for simultaneously reading data from multiple tracks of an optical disk at a high rate. Circuitry is provided for generating a reference data clock independently of spindle motor speed and the spindle motor speed servo circuitry. Circuitry is also provided for deriving individual track data clocks from the reference data clock, while correcting for phase and frequency errors resulting from variations in the linear velocity of the tracks being read, depending upon the radial position of the tracks.

Methods and apparatus for synchronizing read out of data from multiple

Methods and apparatus are provided for improving optical drive access times using a detector having multiple sensing elements to sense and count disk tracks. The detector may be oriented either radially or tangentially with respect to the disk radius, and either capable of sensing more than one disk location simultaneously or have a length greater than the maximum distance between detectable features of the disk.

Methods and apparatus for reducing the access time of an optical drive

Focussing system methods and apparatus are provided for apparatus capable of simultaneously reading multiple tracks of an optical disk. Astigmatism introduced by a cylindrical lens disposed adjacent to the light source, or before the focus detectors arranged at the edge of a wide-area field of illumination, is used to compute an error signal corresponding to the degree of out-of-focus, which error signal is provided to a servo-system that moves the objective lens to correct the focus. An alternative embodiment employs a pair of focus detectors and a pair of micro-lenses having different focal lengths that directs the reflected light onto the focus detectors to generate a focus correction signal. Further alternative embodiments of employing the astigmatism method of focussing are described.

Focussing system and methods for multi- track optical disk apparatus

Focussing system and methods for multi-track optical disk apparatus

Methods and apparatus are provided for simultaneously reading data from multiple tracks of an optical disk at a high rate. Circuitry is provided for use with a detector matrix to read and buffer data in parallel from the multiple adjacent tracks, while asynchronously providing processed data to a host processor. Circuitry is also provided for electronic tracking of tracks on the optical disk and for reducing cross-talk between adjacent tracks. Circuitry is further provided for correcting phase errors resulting from variations in the linear velocity of the tracks being read, depending upon the radial position of the tracks.

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Kfar Saba, Israel

Jacob Finkelstein