Patents by Inventor Ryoji Takeyari
Ryoji Takeyari 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).
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Publication number: 20020005974Abstract: An optical receiver generates a voltage signal having a predetermined swing from a current signal, and feeds the voltage signal to a decision circuit. An optical receiving element receives the input optical signal, converts the optical signal to a current signal, and provides the current signal to a preamplifier, which converts the input current signal into a voltage signal. The voltage signal is input to an amplifier having a limiting function, which linearly amplifies the voltage signal when the swing of the voltage signal is smaller than a predetermined value, and limitedly amplifies the voltage signal when the voltage signal is greater than the predetermined value. An automatic-gain-control amplifier receives the output from the amplifier with the limiting function, and amplifies the input voltage signal to a voltage signal having a constant swing.Type: ApplicationFiled: September 6, 2001Publication date: January 17, 2002Applicant: Hitachi, Ltd.Inventors: Kenichi Ohhata, Ryoji Takeyari, Toru Masuda, Katsuyoshi Washio, Yasushi Hatta
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Patent number: 6304357Abstract: An optical receiver generates a voltage signal having a predetermined swing from a current signal, and feeds the voltage signal to a decision circuit. An optical receiving element receives the input optical signal, converts the optical signal to a current signal, and provides the current signal to a preamplifier, which converts the input current signal into a voltage signal. The voltage signal is input to an amplifier having a limiting function, which linearly amplifies the voltage signal when the swing of the voltage signal is smaller than a predetermined value, and limitedly amplifies the voltage signal when the voltage signal is greater than the predetermined value. An automatic-gain-control amplifier receives the output from the amplifier with the limiting function, and amplifies the input voltage signal to a voltage signal having a constant swing.Type: GrantFiled: March 13, 1998Date of Patent: October 16, 2001Assignees: Hitachi, Ltd., Hitachi Device Engineering Co., Ltd.Inventors: Kenichi Ohhata, Ryoji Takeyari, Toru Masuda, Katsuyoshi Washio, Yasushi Hatta
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Patent number: 6266169Abstract: An optical transmission system accomplishes optical transmission over a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission over a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-to-electric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, and with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: October 1, 1999Date of Patent: July 24, 2001Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Ryoji Takeyari, Hiroyuki Nakano
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Patent number: 6018405Abstract: An optical transmission system accomplishes optical transmission over a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission over a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-toelectric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, and with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: February 5, 1999Date of Patent: January 25, 2000Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Ryoji Takeyari, Hiroyuki Nakano
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Patent number: 6005699Abstract: An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-to-electric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, an with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: September 11, 1997Date of Patent: December 21, 1999Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Ryoji Takeyari, Hiroyuki Nakano
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Patent number: 5875046Abstract: An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-to electric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, and with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: November 5, 1996Date of Patent: February 23, 1999Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Ryoji Takeyari, Hiroyuki Nakano
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Patent number: 5861972Abstract: An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-toelectric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, an with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: November 6, 1996Date of Patent: January 19, 1999Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Ryoji Takeyari, Hiroyuki Nakano
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Patent number: 5844445Abstract: A pre-amplifier disclosed in which low noise at the time of small input and linear amplification at the time of large input are compatible. In a pre-amplifier, such compatibility can be realized by constituting a current mirror circuit, with respect to a current of a first stage transistor in a transimpedance portion, by a by-passing transistor which is provided at an input side of the pre-amplifier. In such a configuration, by making a by-pass current flow proportionally to an input instantaneous current at the time of a large input, the transimpedance can be made small equivalently to thereby widen the dynamic range.Type: GrantFiled: October 25, 1996Date of Patent: December 1, 1998Assignee: Hitachi, Ltd.Inventor: Ryoji Takeyari
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Patent number: 5838475Abstract: A a first clock extraction device included in the receiving section of the optical regenerator recovers a receiving clock. The receiving clock follows the jitter contained in a receiving optical signal caused by fiber wavelength dispersion. The receiving optical signal is detected in synchrony with the receiving clock. A transmission section includes a transmitter for generating a transmission optical signal changed in phase in such a manner as to suppress the stimulated Brillouin scattering and a second clock extraction device for regenerating the transmission clock not following the jitter. The data of the receiving optical signal is processed at a processing unit, and intensity-modulated on the basis of the data thus processed. The timing of this modulation is synchronized with the transmission clock. The receiving clock is synchronized with the jitter, and therefore no logic error occurs. Since the transmission clock does not follow the jitter, the jitter is prevented from accumulating.Type: GrantFiled: November 6, 1996Date of Patent: November 17, 1998Assignees: Hitachi, Ltd., Nippon Telegraph and Telephone CorporationInventors: Ryoji Takeyari, Takashi Funada, Yukihiko Wakai, Kazuo Hagimoto
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Patent number: 5812289Abstract: An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-toelectric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, and with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: August 29, 1996Date of Patent: September 22, 1998Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Ryoji Takeyari, Hiroyuki Nakano
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Patent number: 5801864Abstract: An optical frequency division multiplexing network includes first optical communication paths connected to terminals, respectively, a second optical communication path connected to the outside and a node composed of a selection unit for selecting signals having optical frequencies to be sent to the plurality of terminals, respectively, from signals transmitted through the second optical communication path in optical frequency division multiplexing, a conversion unit for converting the selected signals into signals having a single optical frequency and an output unit for producing the converted signals to the terminals through the first optical communication paths, respectively.Type: GrantFiled: February 29, 1996Date of Patent: September 1, 1998Assignee: Hitachi, Ltd.Inventors: Atsushi Takai, Ryoji Takeyari, Akihiko Takase
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Patent number: 5739932Abstract: An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-to-electric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, an with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: June 20, 1996Date of Patent: April 14, 1998Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Ryoji Takeyari, Hiroyuki Nakano
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Patent number: 5612959Abstract: Distributed LANs are connected to a wide area network through terminal adapters, which are interconnected by virtual circuits to form a logical bus network. Each terminal adapter copies cells received through the virtual circuit that is allocated for multicasting, and transfers the copied cells to the adjacent terminal adapters via preset virtual circuits. The terminal adapters assemble a part or all of the transmitted message from the received cells and, according to the contents of the assembled message, transfer the copies of the cells to the adjacent terminal adapters through predetermined virtual circuits.Type: GrantFiled: July 6, 1993Date of Patent: March 18, 1997Assignee: Hitachi, Ltd.Inventors: Akihiko Takase, Shiro Tanabe, Noboru Endo, Ryoji Takeyari, Yusuke Mishina, Toshiya Oouchi, Junichirou Yanagi
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Patent number: 5576876Abstract: A a first clock extraction device included in the receiving section of the optical regenerator recovers a receiving clock. The receiving clock follows the jitter contained in a receiving optical signal caused by fiber wavelength dispersion. The receiving optical signal is detected in synchrony with the receiving clock. A transmission section includes a transmitter for generating a transmission optical signal changed in phase in such a manner as to suppress the stimulated Brillouin scattering and a second clock extraction device for regenerating the transmission clock not following the jitter. The data of the receiving optical signal is processed at a processing unit, and intensity-modulated on the basis of the data thus processed. The timing of this modulation is synchronized with the transmission clock. The receiving clock is synchronized with the jitter, and therefore no logic error occurs. Since the transmission clock does not follow the jitter, the jitter is prevented from accumulating.Type: GrantFiled: February 7, 1995Date of Patent: November 19, 1996Assignees: Hitachi, Ltd., Nippon Telegraph and Telephone CorporationInventors: Ryoji Takeyari, Takashi Funada, Yukihiko Wakai, Kazuo Hagimoto
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Patent number: 5555477Abstract: An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-to-electric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, an with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: April 7, 1993Date of Patent: September 10, 1996Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Ryoji Takeyari, Hiroyuki Nakano
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Patent number: 5510921Abstract: An optical frequency division multiplexing network includes first optical communication paths connected to terminals, respectively, a second optical communication path connected to the outside and a node composed of a selection unit for selecting signals having optical frequencies to be sent to the plurality of terminals, respectively, from signals transmitted through the second optical communication path in optical frequency division multiplexing, a conversion unit for converting the selected signals into signals having a single optical frequency and an output unit for producing the converted signals to the terminals through the first optical communication paths, respectively.Type: GrantFiled: April 28, 1994Date of Patent: April 23, 1996Assignee: Hitachi, Ltd.Inventors: Atsushi Takai, Ryoji Takeyari, Akihiko Takase
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Patent number: 5506711Abstract: A star type multi-stage network having the same connectivity graph between stages and having a physical topology of a star form, comprises a plurality of columns assigned with different specific transmission wavelengths, respectively, NIU's each including a transmitter for making a transmission on a wavelength assigned to a column to which that NIU (network interface unit) belongs and a receiver for receiving a wavelength assigned to a column from which reception is to be made, and a fundamental connection section including a connection portion formed by optical fibers or optical waveguides to provide a fundamental connection pattern between stages. Inputs and outputs of the optical fibers or optical waveguides are connected to couplers having inputs or outputs the number of which is equal to at least the number of the transmitters of the NIU's. Outputs of the transmitters of the NIU's are connected to inputs of the fundamental connection section corresponding to connectivity between stages.Type: GrantFiled: August 13, 1992Date of Patent: April 9, 1996Assignee: Hitachi, Ltd.Inventor: Ryoji Takeyari
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Patent number: 5438444Abstract: An optical routing system where a time-division multiplexing signal train passes through a front stage semiconductor laser amplifier and detects information of a header and is multiplexed with a local oscillator light from a variable wavelength light source and passes through a rear stage semiconductor laser amplifier, and then is demultiplexed by an optical wavelength division demultiplexer and is outputted to an output side optical signal transmission fiber and an intermediate output port. Wavelength of the local oscillator light and selective wavelength of the optical wavelength division demultiplexer are selected so that a packet is outputted to an assigned intermediate output port. Thereby for the time-division multiplexing optical signal train, while the optical signal train as a whole is held, a specified part or a packet can be distributed.Type: GrantFiled: September 8, 1993Date of Patent: August 1, 1995Assignee: Hitachi, Ltd.Inventors: Takashi Tayonaka, Shinji Tsuji, Ryoji Takeyari
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Patent number: 5323258Abstract: A homodyne optical receiver includes a polarization beam splitter for dividing an optical signal into an optical signal with horizontal polarization and an optical signal with vertical polarization. Optical couplers combine two optical signals of the two polarized components with two optical local signals, which signals are almost matched therewith in polarization, and in a state where they are matched with each other in phase. Detectors homodyne-detect respective output optical signals of the optical couplers and two weighting circuits assign output signals of the detectors weights which are approximately proportional to amplitudes thereof, respectively. An adder adds output signals of the weighting circuits.Type: GrantFiled: October 4, 1991Date of Patent: June 21, 1994Assignee: Hitachi, Ltd.Inventors: Hideaki Tsushima, Ryoji Takeyari, Shinya Sasaki, Shigeki Kitajima, Katsuhiko Kuboki
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Patent number: 5321540Abstract: An optical frequency division multiplexing network includes first optical communication paths connected to terminals, respectively, a second optical communication path connected to the outside and a node composed of a selection unit for selecting signals having optical frequencies to be sent to the plurality of terminals, respectively, from signals transmitted through the second optical communication path in optical frequency division multiplexing, a conversion unit for converting the selected signals into signals having a single optical frequency and an output unit for producing the converted signals to the terminals through the first optical communication paths, respectively.Type: GrantFiled: November 29, 1991Date of Patent: June 14, 1994Assignee: Hitachi, Ltd.Inventors: Atsushi Takai, Ryoji Takeyari, Akihiko Takase