Patents Assigned to Hitachi Communication System, Inc.
  • Patent number: 5600630
    Abstract: An ATM path changing system and method for use in an ATM communication apparatus and ATM communication network are provided which can set an alternating route in the event of a failure occurring in a transmission line or VP. A header converter in a line controller includes a plurality of output path routing tables, a selector, a comparator, a register for failure RTG and a register for failure VPI and when the contents of the register for failure RTG or VPI coincides with a RTG or VPI of the output path routing tables, an output is selected in accordance with the contents of a selected emergency-route RTG or VPI register.
    Type: Grant
    Filed: August 25, 1994
    Date of Patent: February 4, 1997
    Assignees: Hitachi, Ltd., Hitachi Communication Systems, Inc.
    Inventors: Masataka Takano, Yoji Oka, Akihiko Takase, Setsuo Takahashi
  • Patent number: 5563940
    Abstract: In an incoming call service by which an extension can be directly called when a call comes in from another office, a dedicated terminal for selecting an extension to which the incoming call is connected is installed to enable the user to select it as desired, thereby increasing usage of call incoming lines for effective use. An exchange which connects an incoming call from another office directly to an extension, an input device for accepting specification of an extension corresponding to a specific incoming call, and a controller which includes a definition device for defining the correspondence between the specific incoming call and extension are provided. Upon receipt of an incoming call, the exchange connects the call to its corresponding extension in response to the correspondence defined in the definition device.
    Type: Grant
    Filed: November 15, 1995
    Date of Patent: October 8, 1996
    Assignees: Hitachi, Ltd., Hitachi Software Engineering Co., Ltd., Hitachi Communications Systems, Inc.
    Inventors: Takuo Tsuzuki, Masahiro Kumon, Yoshiharu Kondoh, Mitsuhiro Kotake, Masayuki Hashimura
  • Patent number: 5541992
    Abstract: In an incoming call service by which an extension can be directly called when a call comes in from another office, a dedicated terminal for selecting an extension to which the incoming call is connected is installed to enable the user to select it as desired, thereby increasing usage of call incoming lines for effective use. An exchange which connects an incoming call from another office directly to an extension, an input device for accepting specification of an extension corresponding to a specific incoming call, and a controller which includes a definition device for defining the correspondence between the specific incoming call and extension are provided. Upon receipt of an incoming call, the exchange connects the call to its corresponding extension in response to the correspondence defined in the definition device.
    Type: Grant
    Filed: June 11, 1993
    Date of Patent: July 30, 1996
    Assignees: Hitachi, Ltd., Hitachi Software Engineering Co., Ltd., Hitachi Communication Systems, Inc.
    Inventors: Takuo Tsuzuki, Masahiro Kumon, Yoshiharu Kondoh, Mitsuhiro Kotake, Masayuki Hashimura
  • Patent number: 5506783
    Abstract: A method of determining supply sequence of products to be processed to an N-step flow shop type production line, where N is an integer N greater than or equal to 2, is disclosed.
    Type: Grant
    Filed: June 29, 1994
    Date of Patent: April 9, 1996
    Assignees: Hitachi, Ltd., Hitachi Communication Systems, Inc.
    Inventors: Kiyofumi Tanaka, Junichi Ikebe, Hidetoshi Haga
  • Patent number: 5495186
    Abstract: A differential type MOS transmission circuit includes a signal driving circuit and a signal receiving circuit to realize high speed transmission for a short distance transmission between different LSIs, etc. A pair of transmission lines between the signal driving circuit and the signal receiving circuit are driven by a pair of drivers in the signal driving circuit so as to take either one of three states, i.e. one state where both of the lines are in a precharged states and two states where either one of the lines is in a discharged state. A signal driving circuit includes signal generating circuits generating variations in control signals varying pulse-like in response to rise and fall of an input signal to thereby obtain the discharge state.
    Type: Grant
    Filed: July 13, 1994
    Date of Patent: February 27, 1996
    Assignees: Hitachi, Ltd., Hitachi Communication Systems, Inc.
    Inventors: Nobuaki Kanazawa, Masao Mizukami, Kunihiro Ito
  • Patent number: 5444740
    Abstract: A signal transmission system provides stable, fast, long-range transmission. During transmission, a short-width pulse is synchronized with rising and falling edges of a transmission pulse signal. A ternary output signal in a differential shape is produced on the basis of the pulse, and an output signal is transmitted through series resistors via a pair of transmitting wirings. During reception, a reception terminal is provided with terminal resistors corresponding to a characteristic impedance of the transmitting wirings. A signal having passed through one of the transmitting wirings is detected with reference to a signal having passed through the other transmitting wiring. A signal having passed through the other transmitting wiring is detected with reference to the signal having passed through the one transmitting wiring. Additionally, the original pulse signal is restored and reproduced on the basis of the detected signals.
    Type: Grant
    Filed: September 3, 1993
    Date of Patent: August 22, 1995
    Assignees: Hitachi, Ltd., Hitachi Communication Systems, Inc.
    Inventors: Masao Mizukami, Nobuaki Kanazawa
  • Patent number: 5371755
    Abstract: An optical transmitter can communicate at a transmission speed exceeding Gb/s with a low bit error rate. An optical transmission module includes a semiconductor module having a semiconductor laser and an impedance matching element, a driver circuit for driving the semiconductor laser to emit an optical signal, and an optical fiber for transmitting the optical signal. The impedance matching element matches an impedance of the semiconductor laser module to an impedance of the driver circuit. The optical transmission module includes an impedance element for reducing an input impedance of the semiconductor laser module as viewed from the driving circuit in order to reduce a fall time of the optical signal. Impedance matching elements and are added to remove possible mismatching between the module and the driver circuit caused by a manufacturing error and to improve the yield of the module.
    Type: Grant
    Filed: March 5, 1993
    Date of Patent: December 6, 1994
    Assignees: Hitachi, Ltd., Hitachi Communication System Inc.
    Inventors: Atsushi Murata, Nobuhiro Matsudaira, Yuuki Sato
  • Patent number: 5351238
    Abstract: A frame phase variable time-division switch according to the present invention comprises an input highway, a data memory for storing data multiplexed on the data highway, an output highway to which data read out of the data memory is outputted, a control memory for storing a write address or a read address of the data memory, a write counter for generating a write pulse, a read counter for generating a read pulse, a write reset terminal for inputting a pulse for controlling the phase of the write counter, and a read reset terminal for inputting a pulse for controlling the phase of the read counter.
    Type: Grant
    Filed: June 24, 1991
    Date of Patent: September 27, 1994
    Assignees: Hitachi, Ltd., Hitachi Communication System Inc.
    Inventors: Yoshihiro Ashi, Yukio Nakano, Kenji Takeda
  • Patent number: 5267245
    Abstract: A communication control unit for integrated service digital network (ISDN) is disclosed. The ISDN communication control unit includes a data communication adapter for transmitting and receiving data to and from the ISDN and a voice adapter for transmitting and receiving voice data received from the ISDN, through the data communication adapter. The voice adapter includes a memory for storing voice data, a compression and expansion circuit for voice data, a temporary storage circuit for voice data, a monitor unit for voice data, a communication path change-over circuit for changing over a communication path between said temporary storage circuit, said monitor circuit and the ISDN, and a control unit for controlling these. A communication path is changed over by the communication path change-over circuit, to mutually transmit and receive voice data between the temporary storage circuit, the monitor circuit and the ISDN.
    Type: Grant
    Filed: February 21, 1991
    Date of Patent: November 30, 1993
    Assignees: Hitachi, Ltd., Hitachi Communication System, Inc.
    Inventors: Kazuhiko Maruyama, Yosinori Tuzita, Tomoyuki Yukawa, Toru Saito, Yutaka Kawakita
  • Patent number: 5237590
    Abstract: A timing clock extraction circuit for extracting from a multilevel code signal, transmitted at a predetermined baud rate, in which cross timings with a reference level are generated at frequency timings several times the baud rate, a clock pulse train at the baud rate and obtaining discriminative data from the multilevel code signal in accordance with the extracted clock pulse train.
    Type: Grant
    Filed: December 11, 1991
    Date of Patent: August 17, 1993
    Assignees: Hitachi, Ltd., Hitachi Communication Systems, Inc.
    Inventors: Tohru Kazawa, Toshiro Suzuki, Takashi Morita, Souichi Yamashima
  • Patent number: 5022057
    Abstract: A telephone exchange system has a plurality of bit synchronization circuit each provided for an individual subscriber's line. A single clock generating circuit which generates a plurality of clocks is provided in common to the plurality of bit synchronization circuits. The bit synchronization circuit selects one clock of a phase suitable for regenerating an input data signal among the plurality of clocks applied thereto by the clock generating circuit, and regenerates and phases the input data signal by using the selected clock.
    Type: Grant
    Filed: March 9, 1989
    Date of Patent: June 4, 1991
    Assignees: Hitachi, Ltd., Hitachi Communication Systems, Inc.
    Inventors: Yumiko Nishi, Yutaka Torii, Norihumi Komatu, Seiichi Takaki
  • Patent number: 5010269
    Abstract: A SAW resonator includes resonating SAW transducer units formed on a piezoelectric substrate and juxtaposed in a direction of propagation of acoustic waves, and a unidirectionally reflecting SAW transducer unit provided in each end of the juxtaposed resonating SAW transducer units on the substrate. Each resonating SAW transducer unit includes first and second SAW transducers connected in series and/or in parallel with each other.
    Type: Grant
    Filed: December 9, 1988
    Date of Patent: April 23, 1991
    Assignees: Hitachi, Ltd., Hitachi Denshi Kabushiki Kaisha, Hitachi Communication System, Inc.
    Inventors: Mitsutaka Hikita, Atsushi Sumioka, Toyoji Tabuchi, Kazuhito Kurosawa, Tuneo Kinoshita