Patents by Inventor Imao Usimaru

Imao Usimaru 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: 5332980
    Abstract: A modulation circuit utilized in a mobile radio communication transmitter includes an amplifier for amplifying a modulation signal and a modulator having a voltage-controlled oscillator for generating a frequency modulation signal corresponding to the modulation signal. An amplifier controller applies a first predetermined constant direct current voltage V.sub.1 to a power source of the amplifier when the frequency of the modulation signal is less than a predetermined frequency f.sub.3, and for a second predetermined constant direct current voltage V.sub.2 to a power source of the amplifier when the frequency of the modulation signal is higher than the frequency f.sub.3. Thus, when the frequency of the modulation signal is less than the frequency f.sub.3, the amplitude of the modulation signal which is added to the voltage-controlled oscillator decreases by a predetermined value compared with the case where the frequency of the modulation signal is higher than the frequency f.sub.3.
    Type: Grant
    Filed: September 23, 1992
    Date of Patent: July 26, 1994
    Assignee: Fujitsu Limited
    Inventor: Imao Usimaru
  • Patent number: 5315185
    Abstract: A switching noise cancelling system in a space diversity receiving system, comprising a comparator for comparing two receiving signal levels received by two antennas to provide a high level signal or a low level signal in response to the result of the comparison, a first switch for selecting, in response to the output signal of the comparator, one of two signals received by the antennas, a noise generating unit for generating noises substantially the same as noises generated by the switch, and a noise cancelling unit for cancelling the noises generated by the first switch by using the noises generated by the noise generating unit, whereby noises generated by the switch are canceled.
    Type: Grant
    Filed: September 30, 1992
    Date of Patent: May 24, 1994
    Assignee: Fujitsu Limited
    Inventor: Imao Usimaru