Patents Assigned to Discovision Associates
  • Patent number: 5689313
    Abstract: This invention provides a method to control the buffering of encoded video data organized as frames or fields. This method involves determining the picture number of each incoming decoded frame, determining the expected presentation number at any time and marking any buffer as ready when its picture number is on or after the presentation number.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: November 18, 1997
    Assignee: Discovision Associates
    Inventor: Martin William Sotheran
  • Patent number: 5689485
    Abstract: An apparatus is disclosed for control of a beam of radiant energy, wherein a detector of the beam has first and second outputs responsive to a position of the beam. A circuit is coupled to the outputs of the detector for producing an error signal representing a displacement of the beam from a predetermined position, wherein the error signal has a periodic characteristic relative to the displacement. A servo responsive to the error signal restores the displaced beam to the predetermined position. A local feedback loop is coupled to the outputs of the detector, and includes first and second periodic function generators, each responsive to the error signal. The second periodic function generator has an output that differs from an output of the first periodic function generator by a phase angle, preferably 90 degrees. A first multiplier multiplies the first output of the detector by the output of the first periodic function generator.
    Type: Grant
    Filed: April 1, 1996
    Date of Patent: November 18, 1997
    Assignee: Discovision Associates
    Inventor: Ludwig Ceshkovsky
  • Patent number: 5684776
    Abstract: The mechanism for loading and unloading a disk cartridge uses two sliders (one on each side of a base plate), which move in opposite directions under the influence of a tiller. Each slider has a slot to receive one of the two lifting pins provided on the cartridge receiver. The movement of the sliders drives the lifting pins along the slots, thereby raising or lowering the cartridge receiver depending upon the direction of rotation of the tiller. The sliding motion of the lifting pins engaged in the S-shaped slots thus unloads a disk from or, alternatively, loads the disk onto the drive spindle. As the lifting pins travel along their respective slots, the lifting and lowering of the disk is accomplished in such a manner that the disk hub is peeled from the spindle magnet rather than being lifted vertically off the spindle. This reduces the peak force required to break the magnetic clamp force between the spindle magnet and the disk hub.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: November 4, 1997
    Assignee: Discovision Associates
    Inventors: Marvin B. Davis, Kent Murphy
  • Patent number: 5682367
    Abstract: A first write encoder encodes digital data in a first, high-density format. A second write encoder encodes digital data in a second, low-density (i.e., ANSI) format. A first read decoder decodes digital data from the first format. A second read decoder decodes digital data from the second format. A disk drive receives a replaceable 90 millimeter optical disk. A read/write head reads encoded data from and writes encoded data to a 90 millimeter optical disk received by the drive. In a first mode, the first write encoder is connected between a source of digital data and the read/write head, and the first read decoder is connected between the read/write head and the utilizing apparatus. In a second mode, the second write encoder is connected between the source and the read/write head, and the second read decoder is connected between the read/write head and the utilizing apparatus.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: October 28, 1997
    Assignee: Discovision Associates
    Inventors: Noboru Kimura, Ronald G. Vitullo, Yasuhiro Yamazaki
  • Patent number: 5677899
    Abstract: A method for moving a carriage assembly from an initial position to a target position relative to a storage medium rotating at a circumferential velocity. The method includes the steps of determining a first radial distance between the initial position and a center of the storage medium, determining a second radial distance between the target position and the center of the storage medium, determining a circumferential distance between the initial position and the target position, determining an initial circumferential velocity of the storage medium, calculating a velocity trajectory relative to the first radial distance, the second radial distance, the circumferential distance, and the initial circumferential velocity, and moving the carriage assembly from the initial position to the target position substantially at the velocity trajectory. The velocity trajectory is calculated such that the carriage assembly will arrive radially and circumferentially at the target position at substantially the same time.
    Type: Grant
    Filed: April 11, 1995
    Date of Patent: October 14, 1997
    Assignee: Discovision Associates
    Inventor: Kurt W. Getreuer
  • Patent number: 5677648
    Abstract: An improved phase locked loop utilizing control logic generated by a phase detector to eliminate sensitivity to uncorrelated noise when the loop is in lock.
    Type: Grant
    Filed: March 1, 1995
    Date of Patent: October 14, 1997
    Assignee: Discovision Associates
    Inventor: Anthony Mark Jones
  • Patent number: 5675413
    Abstract: An adjustable optical system for determining aberration in a source beam by comparison of a test beam with a reference beam. The system includes a test source for producing a source beam having a spacial intensity distribution including an aberration component, a wavefront analyzer for processing a fringe signal associated with the aberration component, and an interferometer interposed between the test source and wavefront analyzer. The interferometer includes a beamsplitter for splitting the source beam into a test beam and a reference beam, a mirror disposed in the test beam path, and a micromirror disposed in the reference beam path. The micromirror reflects a central portion of the reference beam toward an imaging device and allows an outer portion of the reference beam to pass thereby.
    Type: Grant
    Filed: September 20, 1996
    Date of Patent: October 7, 1997
    Assignee: Discovision Associates
    Inventors: Ivan Prikryl, Hollis O'Neal Hall
  • Patent number: 5668831
    Abstract: An integrated digital communication system utilizing multilevel vestigial sideband transmission is provided. The communication system receives a multi-level pulse-amplitude modulated digital signal from a limited bandwidth channel. The system includes processing stages which demodulate, sample and filter the incoming signal prior to recovery of the digital data. Other stages recover the timing and lock on to the frequency and phase of the transmitted signal, as well as provide for automatic gain control. An adaptive equalizer, error correction circuitry, and an output interface recover the digital data and provide for transfer to other devices.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: September 16, 1997
    Assignee: Discovision Associates
    Inventors: Anthony Peter J. Claydon, Charles D. MacFarlane, Richard J. Gammack, Anthony Mark Jones, William P. Robbins, Mark Barnes
  • Patent number: 5666333
    Abstract: There is disclosed an apparatus for controlling the strength of a magnetic field, comprising a first controller, a second controller, a digital-to-analog converter, a current driver, and a bias coil. The first controller determines the position of the focal point of a lens and passes it to the second controller, which provides a digital signal related to the position. The digital-to-analog converter converts the digital signal to a driver voltage and passes the driver voltage to a current driver, which provides to the bias coil a bias current related to the driver voltage. The bias coil produces a magnetic field having a strength related to the bias current. The second controller accounts for stray magnetic fields in creating the digital signal. The stray magnetic fields may be constant or may vary in strength based on position of the objective lens, circumferential velocity of the storage medium, or longitudinal velocity of the storage medium.
    Type: Grant
    Filed: April 7, 1995
    Date of Patent: September 9, 1997
    Assignee: Discovision Associates
    Inventor: David E. Lewis
  • Patent number: 5659535
    Abstract: A method for detecting transitions in an input signal having a DC component. The method includes the steps of generating a threshold signal from the input signal, comparing the input signal to the threshold signal to thereby generate an output signal, and adjusting the threshold signal in response to the output signal. In one preferred embodiment, the method is employed to retrieve data from an information storage device.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: August 19, 1997
    Assignee: Discovision Associates
    Inventors: Noboru Kimura, Wen-Yung Yeh
  • Patent number: 5659526
    Abstract: An apparatus for moving an optical head from an initial track to a target track on a storage medium and generating a track crossing signal is disclosed. The apparatus comprises a sensor for measuring the reflectivity level from a storage medium, a preamplifier for generating a data signal, a tracking error signal generator responsive to the reflectivity level for deriving a tracking error signal, a track/hold selector to direct the tracking error signal generator to generate a corrected tracking error signal of a constant amplitude for a predetermined period of time based on the data signal, and a track crossing signal generator based on the corrected tracking error signal for deriving a track crossing signal indicating the crossing of an information track by the optical head.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: August 19, 1997
    Assignee: Discovision Associates
    Inventor: David E. Lewis
  • Patent number: 5657164
    Abstract: An optical beamsplitter comprises a right angle prism having a hypotenuse and two legs wherein the hypotenuse includes an optically selective coating deposited thereon. An optical element is positioned adjacent the hypotenuse such that the hypotenuse and the optical element form a beamsplitting interface. Various optical elements are utilized to achieve the desired spatial and angular relationships between incoming and outgoing light beams. Several embodiments are disclosed wherein the optical element can comprise a flat plate for providing spatial offset, a wedged plate for producing spatial and angular offset, a lens for adding optical power, or a faceted thin plate.
    Type: Grant
    Filed: May 22, 1995
    Date of Patent: August 12, 1997
    Assignee: Discovision Associates
    Inventor: Curtis A. Shuman
  • Patent number: 5650874
    Abstract: An optical beamsplitter comprises a right angle prism having a hypotenuse and two legs wherein the hypotenuse includes an optically selective coating deposited thereon. An optical element is positioned adjacent the hypotenuse such that the hypotenuse and the optical element form a beamsplitting interface. Various optical elements are utilized to achieve the desired spatial and angular relationships between incoming and outgoing light beams. Several embodiments are disclosed wherein the optical element can comprise a flat plate for providing spatial offset, a wedged plate for producing spatial and angular offset, a lens for adding optical power, or a faceted thin plate.
    Type: Grant
    Filed: September 18, 1996
    Date of Patent: July 22, 1997
    Assignee: Discovision Associates
    Inventor: Curtis A. Shuman
  • Patent number: 5646778
    Abstract: An optical beamsplitter comprises a right angle prism having a hypotenuse and two legs wherein the hypotenuse includes an optically selective coating deposited thereon. An optical element is positioned adjacent the hypotenuse such that the hypotenuse and the optical element form a beamsplitting interface. Various optical elements are utilized to achieve the desired spatial and angular relationships between incoming and outgoing light beams. Several embodiments are disclosed wherein the optical element can comprise a flat plate for providing spatial offset, a wedged plate for producing spatial and angular offset, a lens for adding optical power, or a faceted thin plate.
    Type: Grant
    Filed: May 22, 1995
    Date of Patent: July 8, 1997
    Assignee: Discovision Associates
    Inventor: Curtis A. Shuman
  • Patent number: 5635864
    Abstract: A high speed analog-to-digital converter employs a comparator having first and second units cross coupled in a positive feedback loop. The units are alternately connected to an input voltage and a reference voltage, after which positive feedback is introduced established, and a differential output established. The arrangement is fully symmetric, and balanced and rejects common-mode switching noise.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: June 3, 1997
    Assignee: Discovision Associates
    Inventor: Anthony M. Jones
  • Patent number: 5625571
    Abstract: An apparatus is disclosed for processing video information using a first and a second prediction filter circuit which are substantially identical, and a control signal to process video information encoded in multiple standards. A filter circuit, such as may be used in such an apparatus, for use in video decompression comprises a prediction filter formatter, a first one-dimensional prediction filter, a dimension buffer, and a second one-dimensional prediction filter. A prediction filter, such as may be used in such a filter circuit, may comprise six registers, two multiplexers, and two summing circuits. A first register is connected to a first summing circuit. A second register is connected to a first multiplexer, which is connected to the first summing circuit. The first summing circuit is connected to a third register. A fourth register is connected to a second multiplexer, which is connected to a fifth register.
    Type: Grant
    Filed: March 7, 1995
    Date of Patent: April 29, 1997
    Assignee: Discovision Associates
    Inventor: Anthony P. J. Claydon
  • Patent number: 5617458
    Abstract: The invention discloses a method and an apparatus for implementing an L phase clock in conjuction with L counters, where L is an integer, to count at a frequency scalable by L.
    Type: Grant
    Filed: December 5, 1995
    Date of Patent: April 1, 1997
    Assignee: Discovision Associates
    Inventors: Anthony M. Jones, David A. Barnes
  • Patent number: 5603012
    Abstract: A multi-standard video decompression apparatus has a plurality of stages interconnected by a two-wire interface arranged as a pipeline processing machine. Control tokens and DATA Tokens pass over the single two-wire interface for carrying both control and data in token format. A token decode circuit is positioned in certain of the stages for recognizing certain of the tokens as control tokens pertinent to that stage and for passing unrecognized control tokens along the pipeline. Reconfiguration processing circuits are positioned in selected stages and are responsive to a recognized control token for reconfiguring such stage to handle an identified DATA Token. A wide variety of unique supporting subsystem circuitry and processing techniques are disclosed for implementing the system.
    Type: Grant
    Filed: March 7, 1995
    Date of Patent: February 11, 1997
    Assignee: Discovision Associates
    Inventor: Martin W. Sotheran
  • Patent number: 5596517
    Abstract: An IDCT, or Inverse Discrete Cosine Transform, method decimates a 2-D IDCT into two 1-D IDCT operations and then operates separately on the even and odd pixel input words. In a common processing step, selected input values are passed directly to output adders and subtractors, while others are multiplied by constant, scaled cosine values. In a pre-common processing step, the lowest-order odd input word is pre-multiplied by .sqroot.2, and the odd input words are summed pairwise before processing in a common processing step. In a post-common processing step, intermediate values corresponding to the processed odd input words are multiplied by predetermined coefficients to form odd resultant values. After calculation of the even and odd resultant values, the high-order and low-order outputs are formed by simple subtraction/addition, respectively, of the odd resultant values from/with the even resultant values. The input values are preferably scaled upward by a factor of .sqroot.2.
    Type: Grant
    Filed: March 7, 1995
    Date of Patent: January 21, 1997
    Assignee: Discovision Associates
    Inventors: Anthony M. Jones, Kevin D. Dewar, Martin W. Sotheran
  • Patent number: 5594678
    Abstract: An IDCT, or Inverse Discrete Cosine Transform, method decimates a 2-D IDCT into two 1-D IDCT operations and then operates separately on the even and odd pixel input words. In a common processing step, selected input values are passed directly to output adders and subtractors, while others are multiplied by constant, scaled cosine values. In a pre-common processing step, the lowest-order odd input word is pre-multiplied by .sqroot.2, and the odd input words are summed pairwise before processing in a common processing step. In a post-common processing step, intermediate values corresponding to the processed odd input words are multiplied by predetermined coefficients to form odd resultant values. After calculation of the even and odd resultant values, the high-order and low-order outputs are formed by simple subtraction/addition, respectively, of the odd resultant values from/with the even resultant values. The input values are preferably scaled upward by a factor of .sqroot.2.
    Type: Grant
    Filed: March 7, 1995
    Date of Patent: January 14, 1997
    Assignee: Discovision Associates
    Inventors: Anthony M. Jones, Kevin D. Dewar, Martin W. Sotheran