Abstract: Methods and apparatus are disclosed for buffering and reordering data blocks read simultaneously from multiple tracks of an optical disk, so that they may be delivered in sequential order to a host computer. The methods involve the use of numerous processes to receive read commands, position an optical pickup, handle memory management tasks, process data blocks as they arrive, and send data blocks to the host computer in sequential order as they become available. The reordering of data blocks is achieved by checking each data block as it arrives in a "read process" to see if it may be linked in a sequential chain with a data block that arrived from the next track. Additionally, methods for determining if a requested data block is in the range of blocks that are currently being read, and methods for determining when the optical pickup may be moved to read the next set of tracks are described.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Methods and apparatus are provided for illuminating an optical disk in a multi-track optical disk reader. A laser beam is collimated and focused onto an area including multiple, adjacent data tracks on the optical disk. To minimize noise caused by interference resulting from the reflection of multiple beams from the optical disk the coherency of the laser beam is reduced. This is accomplished by one or more of the following techniques: passing the laser beam through a multi-mode optical fiber, combining laser beams from multiple independent laser sources, and modulating the laser operating current at high frequency.

Abstract: Track detection methods and apparatus for simultaneous electronic monitoring of the locations of multiple adjacent data tracks is provided. A dedicated tracking detector enables both a longer integration time for developing a tracking signal and decreased processing requirements for developing useful tracking information.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Methods and apparatus are provided for generating focus, tracking, and magnification error signals in an multi-track optical disk reader. An optical pickup assembly for the disk reader includes an optical sensor having multiple sensor elements. Some of the sensor elements contain multiple divisions whose outputs are summed to produce tracking, focus, and magnification error signals. Electronic and optical mechanical systems are provided for correcting or compensating for magnification errors caused by an optical pickup assembly of a multi-track optical disk reader.

Abstract: 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.

Abstract: 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.

Abstract: Methods and apparatus are provided for simultaneously tracking multiple data tracks of an optical disk using a detector matrix formed of a plurality of pixels. Based on track pitch, pixel pitch and predetermined point spread functions of the pixels, a series of simultaneous equations based on sampled pixel data is generated and solved to determine an offset distance between a selected pixel and a selected track and corrected values of the sampled pixel data. Alternatively, the series of equations may be generated, based on sample pixel readout values and a series of weighting coefficients, such that solution of the equations enables the position of a selected track may be determined.

Abstract: 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.

Abstract: A method of reading data from an optical disk comprises providing means for illuminating the required part of the disk and acquiring the optical image of a plurality of tracks, providing a detector matrix comprising a plurality of detectors, each of the detectors being capable of producing an output signal which is proportional to the intensity of the light detected by it causing an optical image corresponding to an illuminated area to fall on the detector matrix, transferring the output signal of the detector matrix to image processing means, determining position coordinates of the track center for each data track, by analyzing the output signal of the detector matrix, saving in memory means expected track center data, comprising position coordinates of the track center located by the analysis of the output signal, and if an actually detected track center is shifted with respect to the expected track center, electronically moving the track center position.

Abstract: A method of writing data simultaneously on a plurality of tracks of an optical disk, comprises providing an array of light sources, each light source being independently modulated, providing means to determine the position of each light source with respect to the center of a given track, and varying the intensity of each light source so as to generate a plurality of writing light beams, each generated by a plurality of adjacent light sources, each of the said light beams having the desired width, intensity and position on the written track.

Abstract: A method of reading data from an optical disk comprises providing means for illuminating the required part of the disk and acquiring the optical image of a plurality of tracks, providing a detector matrix comprising a plurality of detectors, each of the detectors being capable of producing an output signal which is proportional to the intensity of the light detected by it causing an optical image corresponding to an illuminated area to fall on the said detector matrix, transferring the output signal of the detector matrix to image processing means, determining position coordinates of the track center for each data track, by analyzing the output signal of the said detector matrix, saving in memory means expected track center data, comprising position coordinates of the track center located by the analysis of the output signal, and if an actually detected track center is shifted with respect to the expected track center, electronically moving the track center position.

Abstract: An optical disk reader system comprises (1) a wide area illumination source for illuminating at least a part of one track of an optical disk; (2) a detector for detecting light reflected from the optical disk illuminated by the wide area illumination source; and (3) a detector for summing the light in the along-track direction detected by the detector.