Patents by Inventor Hidehiko Sawamura

Hidehiko Sawamura has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5552940
    Abstract: A method and an apparatus for digital signal recording and/or reproduction are disclosed in which tracks are formed sequentially on a recording medium by use of a head unit mounted on a rotary cylinder, an input digital data is recorded in the recording medium, and the digital data thus recorded is reproduced. The input digital data is modulated into a code word having at least d (d: an integer of at least two) successive bits of high- and low-level data in a signal waveform recorded in the recording medium. The timebase of the code word is compressed. The compressed code word is recorded in the tracks of the recording medium by use of the head unit. The code word recorded and compressed in the recording medium is reproduced. The timebase of the reproduced code word is expanded, and the input digital data is reproduced from the expanded code word.
    Type: Grant
    Filed: May 3, 1995
    Date of Patent: September 3, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Masuo Umemoto, Hirotake Ishii, Hidehiko Sawamura, Yoshizumi Eto
  • Patent number: 5247401
    Abstract: A replay equalization circuit for reproducing digital image information recorded on a recording medium includes a transducer for reading the digital image information, an equalization circuit connected to the transducer for equalizing an output of the transducer based on a speed information input, a clock recovery circuit connected to the equalization circuit for extracting a clock signal from an output of the equalization circuit for latching the output of the equalization circuit in response to the clock signal.
    Type: Grant
    Filed: June 12, 1989
    Date of Patent: September 21, 1993
    Assignee: Hitachi, Ltd.
    Inventors: Masuo Umemoto, Hidehiko Sawamura, Yoshizumi Eto