Patents by Inventor Mitsuru Kawanami

Mitsuru Kawanami 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: 4125787
    Abstract: A semiconductor switch circuit comprises a PNPN switch with a PNPN semiconductor four-layered structure equivalently including first and second transistors and a gate terminal, a load current dividing circuit including at least one transistor, a variable impedance bypass circuit including at least one transistor, and a capacitive element. The base and the collector of the transistor included in the load current dividing circuit are connected to the cathode and the anode of the PNPN switch, respectively. The collector and the emitter of the transistor included in the variable impedance bypass circuit are connected to the P-type base of the second transistor of the PNPN switch and to the emitter of the transistor of the load-current-dividing circuit, respectively. The base of the transistor of the variable impedance bypass circuit is connected to the anode of the PNPN switch through the capacitive element and is controlled for gate turn-off operation.
    Type: Grant
    Filed: April 26, 1977
    Date of Patent: November 14, 1978
    Assignee: Hitachi, Ltd.
    Inventors: Ichiro Ohhinata, Shinzi Okuhara, Mitsuru Kawanami, Michio Tokunaga
  • Patent number: 4107472
    Abstract: A plurality of PNPN switches, each permitting current flow in either, i.e., positive or negative, direction, are arranged at the cross points between the rows and the columns of the speech paths so as to form a matrix. The gate trigger terminal of each PNPN switch is connected with a gating current circuit having a high impedance, which circuit is adapted to control ON and OFF operations of the switch. A plurality of means are provided to selectively turn the gate current circuits on and off so that gate current is supplied continuously for the gate terminal of any desired PNPN switch at least for the time during which the corresponding cross point of the matrix is to be electrically bridged.
    Type: Grant
    Filed: July 21, 1976
    Date of Patent: August 15, 1978
    Assignee: Hitachi, Ltd.
    Inventors: Mitsuru Kawanami, Shinzi Okuhara, Takuzi Mukaemachi
  • Patent number: 4071779
    Abstract: A semiconductor switch of a PNPN structure comprises a PNPN switch of an equivalently four-layered structure including a P-type anode, N-type cathode, N-type gate and P-type gate, a first NPN transistor, a second PNP transistor, a level shifting circuit, and an impedance element, wherein the impedance element is connected between the collector and emitter of the first transistor, the first transistor has its collector and emitter connected to the P-type gate and N-type cathode respectively, and the second transistor has its emitter and base connected to the P-type anode and N-type gate, respectively, and has its collector connected to the base of the first transistor through the level shifting circuit.
    Type: Grant
    Filed: August 17, 1976
    Date of Patent: January 31, 1978
    Assignee: Hitachi, Ltd.
    Inventors: Mitsuru Kawanami, Ichiro Ohhinata, Shinzi Okuhara