Patents by Inventor Yoshio Karasawa

Yoshio Karasawa 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: 6317253
    Abstract: In an optical amplifier apparatus for amplifying an incident signal light having wavelengths of 1.06 &mgr;m band, a first optical isolator makes an incident signal light pass therethrough in one direction from an input end to an output end. An optical fiber includes a core mainly composed of silica glass and doped with a predetermined rare-earth element and the other elements, and a cladding of silica glass, and transfers in a single mode the signal light output from the first optical isolator. An optical multiplexer multiplexes an excitation light having an excitation wavelength of 0.8 &mgr;m band with the signal light transferred by the optical fiber, by outputting the excitation light to the optical fiber, and further transfers and outputs the signal light having wavelengths of 1.06 &mgr;m band amplified by induced emission in the optical fiber due to the rare-earth element excited by the excitation light.
    Type: Grant
    Filed: July 9, 1997
    Date of Patent: November 13, 2001
    Assignees: ATR Optical & Radio Comm. Research, Mitsubishi Cables Industries, Ltd.
    Inventors: Tetsuya Miyazaki, Yoshio Karasawa, Minoru Yoshida, Toshikazu Gozen
  • Patent number: 6232927
    Abstract: An array antenna apparatus for use in spread spectrum communications is provided including a plurality of antenna elements aligned on a straight line. The array antenna apparatus is used in a receiving station for receiving spread-spectrum modulated radio signals having a wavelength of a predetermined carrier frequency transmitted from transmitting stations using a two-dimensional RAKE receiving method, and for performing spread spectrum communications in code division multiple access. The plurality of antenna elements are aligned such that an interval between antenna elements adjacent to each other among the plurality of antenna elements is set to a value which is larger than one half the wavelength of the carrier frequency and which is equal to or smaller than sixteen times the wavelength of the carrier frequency so as to generate grating lobes.
    Type: Grant
    Filed: February 17, 1999
    Date of Patent: May 15, 2001
    Assignees: ATR Adaptive Communications Research Laboratories, KDD Corporation
    Inventors: Takashi Inoue, Yoshio Karasawa
  • Patent number: 6106176
    Abstract: There are provided a method and apparatus for printing a print image on a print material by using a print head based on dot information of the print image by causing at least one of the print head and the print material to move to thereby effect relative motion between the print head and the print material at a relative speed dependent on a rotational speed of a DC motor as a drive source. Driving of the DC motor and the print head is controlled for printing of the print image. A distance from a predetermined length start position selected from a front end position, a print start position, and a print end position of the print material to a predetermined length end position at which the relative motion is to be terminated, is set to a predetermined length. Braking of the DC motor is controlled by varying a braking load on the DC motor in dependence on the relative speed and the predetermined length so as to terminate the relative motion at the predetermined length end position.
    Type: Grant
    Filed: February 25, 1999
    Date of Patent: August 22, 2000
    Assignee: Seiko Epson Corporation
    Inventors: Shigekazu Yanagisawa, Yoshio Karasawa, Kenji Watanabe, Tomoyuki Ichikawa, Kenichi Tanabe, Rie Sudo
  • Patent number: 6020850
    Abstract: Disclosed is an optical control type phased array antenna apparatus having an array antenna of antenna elements. An optical signal processor optically processes input high-frequency signals, and outputs optically processed signals including signal components having phases corresponding to directions in which radio wave signals come and having frequencies equal to those of the input high-frequency signals. Then, each frequency converter mixes a received signal with the optically processed signal in correspondence with the antenna element, and outputs a frequency-converted signal having a frequency of a difference between a frequency of the received signal and a frequency of the optically processed signal. Further, a combiner combines the frequency-converted signals.
    Type: Grant
    Filed: August 22, 1997
    Date of Patent: February 1, 2000
    Assignee: ATR Adaptive Communications Research Laboratories
    Inventors: Yu Ji, Keizo Inagaki, Nobuaki Imai, Yoshio Karasawa
  • Patent number: 5868953
    Abstract: A method for manufacturing a magnetic disk substrate includes a step of polishing a glass-ceramic having a crystal phase consisting of crystal grains having an average diameter of less than 3 .mu.m with a polishing material having a grain diameter smaller than the diameter of the crystal grain. In one aspect of the invention, the glass-ceramic includes lithium disilicate (Li.sub.2 O--2SiO.sub.2) and alpha-quartz (alpha-SiO.sub.2) as predominant crystal phases and grown crystal grains of the alpha-quartz each have a globular grain structure consisting of aggregated particles and have a diameter within a range of 0.3 .mu.m-3.0 .mu.m.
    Type: Grant
    Filed: October 31, 1995
    Date of Patent: February 9, 1999
    Assignee: Kabushiki Kaisya Ohara
    Inventors: Masashi Maekawa, Nobuo Kawasaki, Yasuyuki Kawashima, Yoshio Karasawa
  • Patent number: 5722042
    Abstract: A satellite communication system has a double-layered earth orbit satellite constellation with a lower first orbit altitude and a higher second orbit altitude. In the satellite communication system, first and second communication satellites are deployed in respective earth orbits located at the first and second orbit altitudes to each have first and second satellite communication stations, respectively. Small terminals and large terminals are further provided as earth stations on the earth.
    Type: Grant
    Filed: October 12, 1995
    Date of Patent: February 24, 1998
    Assignee: ATR Optical and Radio Communications Research Laboratories
    Inventors: Kazuhiro Kimura, Yoshio Karasawa
  • Patent number: 5585803
    Abstract: In an apparatus and method for controlling an array antenna comprising a plurality of antenna elements arranged so as to be adjacent to each other in a predetermined arrangement configuration, a plurality of received signals received by the antenna elements is transformed into respective pairs of quadrature baseband signals, using a common local oscillation signal, wherein each pair of quadrature baseband signals is orthogonal to each other. Then predetermined first and second data are calculated based on each pair of transformed quadrature baseband signals, and are filtered using a noise suppressing filter. Respective elements of a transformation matrix for in-phase combining are calculated based on the filtered first and second data, and the received signals obtained from the each two antenna elements are put in phase based on the calculated transformation matrix. Thereafter, a plurality of received signals which are put in phase are combined in phase, and an in-phase combined received signal is outputted.
    Type: Grant
    Filed: August 29, 1995
    Date of Patent: December 17, 1996
    Assignee: ATR Optical and Radio Communications Research Labs
    Inventors: Ryu Miura, Toyohisa Tanaka, Yoshio Karasawa, Isamu Chiba
  • Patent number: 5493436
    Abstract: A system for communicating between mobile units and an exchange station, with a radio frequency signal, in which an electric signal from a telephone exchange of the telephone station is converted into an optical signal with an electricity-to-light converter. The optical signal is carried via an optical fiber cable to a transmission communication antenna for emission, with amplification of the optical signal if necessary. The emitted signal is received by a receiving communication antenna, amplified with an optical amplifier if necessary, and converted to an electric signal with a light-to-electricity converter.
    Type: Grant
    Filed: March 21, 1995
    Date of Patent: February 20, 1996
    Assignee: Kokusai Denshin Denwa Company, Limited
    Inventors: Yoshio Karasawa, Takashi Matsudo, Hisato Iwai, Takayasu Shiokawa
  • Patent number: 5473333
    Abstract: In an apparatus for adaptively controlling an array antenna of M antenna elements, a multi-beam forming circuit calculates N beam field strengths in a known manner, and a beam selecting circuit selectively outputs beam field strengths not smaller than a predetermined threshold value by comparing the N beam field strengths with the threshold value. At least two adaptive control processors calculate N weight coefficients corresponding to N beams according to a constant modulus algorithm, respectively multiplies the calculated beam field strengths by the calculated N weight coefficients, and combines in phase respective signals of multiplication results, outputting the combined signal as a reception signal. In an initial state of one adaptive control processor, a weight coefficient thereof corresponding to the maximum beam field strength is set to a predetermined initial value not zero, and weight coefficients corresponding to the other beam field strengths are set to zero.
    Type: Grant
    Filed: January 4, 1995
    Date of Patent: December 5, 1995
    Assignee: ATR Optical & Radio Communications Research Laboratories
    Inventors: Isamu Chiba, Ryu Miura, Yoshio Karasawa
  • Patent number: 5347535
    Abstract: A CDMA communication system using a spreading code has a plurality of mobile stations and at least one base station. The mobile stations and the base station are provided with respective receiving sections, each of which has a path diversity function for reducing multipath fading. The base station includes an array antenna having a plurality of integrated antenna elements spaced by a distance substantially equal to one to several wavelengths from each other so as to produce a space diversity effect. A plurality of delay devices are coupled with the respective antenna elements, for applying time delays to signals which pass through the respective antenna elements. The time delay are different from each other by a one symbol period of the spreading code or more.
    Type: Grant
    Filed: March 3, 1993
    Date of Patent: September 13, 1994
    Assignee: Kokusai Denshin Denwa Co., Ltd.
    Inventors: Yoshio Karasawa, Hisato Iwai
  • Patent number: 5204981
    Abstract: Accordingly to the present invention, when an incidence angle of a direct wave or a satellite elevation angle reaches a predetermined value, signals from two (or more) antennas, which are disposed at positions where variations in the field intensities of radio waves recevied by the two antennas are negatively correlated (i.e. when the received signal level of one of them is low, the received signal level of the other is high) or uncorrelated (i.e. the variations are not related to each other), are successively or discretely switched at a suitable switching period, by which burst-like errors are spread with time to perform the de-interleave or interleave function in decoding transmitted signals.
    Type: Grant
    Filed: March 1, 1991
    Date of Patent: April 20, 1993
    Assignee: Kokusai Denshin Denwa Kabushiki Kaisha
    Inventors: Yoshio Karasawa, Masayuki Yasunaga, Hisato Iwai
  • Patent number: 4853702
    Abstract: A radio wave receiving system comprises an antenna having at least two antenna elements, a phase shifter connected to at least one of the antenna elements, and a combiner for combining signals passed through the phase shifter and other signals not passed through the phase shifter. Through proper control of the mutual phase difference between signals from the aforementioned antenna elements by using the phase shifter, the system alters the polarization characteristic of the antenna in the direction of incidence of undesired reflected waves and consequently supresses the fading due to undesired reflected waves.
    Type: Grant
    Filed: June 12, 1985
    Date of Patent: August 1, 1989
    Assignee: Kokusai Denshin Denwa Kabushiki Kaisha
    Inventors: Takayasu Shiokawa, Koji Yasukawa, Yoshio Karasawa
  • Patent number: 4400703
    Abstract: A compact and light weight array antenna with a gain of approximately 13 dB comprises a plurality of axial-mode helical antennas with an antenna height of 0.4.about.0.6.lambda. (.lambda.: Wavelength) as element antennas, having cylindrical metallic rims with a rim height of approximately 0.25.lambda. surrounding each corresponding element antenna in order to suppress the characteristic degradation of the device caused by the mutual coupling of element antennas.
    Type: Grant
    Filed: June 2, 1981
    Date of Patent: August 23, 1983
    Assignee: Kokusai Denshin Denwa Kabushiki Kaisha
    Inventors: Takayasu Shiokawa, Yoshio Karasawa