Patents by Inventor Tadashi Koga

Tadashi Koga 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).

  • Publication number: 20200084422
    Abstract: In one embodiment, a substrate imaging apparatus includes: a rotary holding unit that holds and rotates a substrate; a mirror member having a reflecting surface that opposes an end face of the substrate and a peripheral portion of a back surface of the substrate held by the rotary holding unit, the reflecting surface being inclined with respect to a rotation axis of the rotary holding unit; and a camera having an imaging device that receives both first light and second light through a lens, the first light coming from a peripheral portion of a front surface of the substrate held by the rotary holding unit, and the second light being a reflected light of second light which comes from the end face of the substrate held by the rotary holding unit and is reflected by the reflecting surface.
    Type: Application
    Filed: November 12, 2019
    Publication date: March 12, 2020
    Applicant: Tokyo Electron Limited
    Inventors: Norihisa KOGA, Tadashi Nishiyama, Yasuaki Noda
  • Patent number: 10523905
    Abstract: In one embodiment, a substrate imaging apparatus includes: a rotary holding unit that holds and rotates a substrate; a mirror member having a reflecting surface that opposes an end face of the substrate and a peripheral portion of a back surface of the substrate held by the rotary holding unit, the reflecting surface being inclined with respect to a rotation axis of the rotary holding unit; and a camera having an imaging device that receives both first light and second light through a lens, the first light coming from a peripheral portion of a front surface of the substrate held by the rotary holding unit, and the second light being a reflected light of second light which comes from the end face of the substrate held by the rotary holding unit and is reflected by the reflecting surface.
    Type: Grant
    Filed: February 21, 2017
    Date of Patent: December 31, 2019
    Assignee: Tokyo Electron Limited
    Inventors: Norihisa Koga, Tadashi Nishiyama, Yasuaki Noda
  • Patent number: 10355786
    Abstract: In order to provide an optical modulator capable of controlling a bias voltage to correspond to transmission characteristics of a modulation means even when a multi-level modulation scheme is applied, an optical modulator 10 is provided with: an amplitude information control means 20that generates amplitude information for controlling the amplitude of an information signal to correspond to transmission characteristics of a modulation means 50, adds a dither signal to the amplitude information, and outputs the amplitude information; a bias value control means 30 that generates and outputs a bias value for controlling the center of the amplitude of the information signal to correspond to the transmission characteristics of the modulation means 50; a data output means 40 that corrects the amplitude of information data on the basis of the amplitude information, and outputs the information data as the information signal; the modulation means 50 that corrects the center of the amplitude of the information signal on
    Type: Grant
    Filed: September 15, 2016
    Date of Patent: July 16, 2019
    Assignee: NEC CORPORATION
    Inventor: Tadashi Koga
  • Publication number: 20190158187
    Abstract: A transmitter includes an optical modulator, a drive unit, a deviation identification signal generation unit, and a bias control unit. The deviation identification signal generation unit generates a signal value in accordance with a deviation of a bias voltage of the optical modulator by amplifying a signal value of a dither signal extracted from a modulated signal output from the optical modulator by a factor set for each of a plurality of modulation schemes so as to generate a uniform signal value. The bias control unit generates a bias value at which a center of a variation range, which is a range from a maximum value to a minimum value of the drive signal, corresponds to transmission characteristics of the optical modulator according to one predetermined adjustment method by using the signal value generated by the deviation identification signal generation unit.
    Type: Application
    Filed: April 3, 2017
    Publication date: May 23, 2019
    Applicant: NEC Corporation
    Inventor: Tadashi KOGA
  • Publication number: 20180269980
    Abstract: In order to provide an optical modulator capable of controlling a bias voltage to correspond to transmission characteristics of a modulation means even when a multi-level modulation scheme is applied, an optical modulator 10 is provided with: an amplitude information control means 20 that generates amplitude information for controlling the amplitude of an information signal to correspond to transmission characteristics of a modulation means 50, adds a dither signal to the amplitude information, and outputs the amplitude information; a bias value control means 30 that generates and outputs a bias value for controlling the center of the amplitude of the information signal to correspond to the transmission characteristics of the modulation means 50; a data output means 40 that corrects the amplitude of information data on the basis of the amplitude information, and outputs the information data as the information signal; the modulation means 50 that corrects the center of the amplitude of the information signal o
    Type: Application
    Filed: September 15, 2016
    Publication date: September 20, 2018
    Applicant: NEC Corporation
    Inventor: Tadashi KOGA
  • Patent number: 9654228
    Abstract: A signal reception processing apparatus includes a digital signal processing unit that calculates a first Q value based on distribution of the symbols of the demodulated signal and distance between the symbols of the demodulated signal, and an error correction unit that outputs corrected signal as a demodulation electric signal, and calculates a second Q value based on an error rate at the time of the correction, and a control unit that calculates a penalty that indicates degradation quantity of signal quality caused by a nonlinear optical effect of an optical fiber based on the first Q value and the second Q value.
    Type: Grant
    Filed: October 19, 2015
    Date of Patent: May 16, 2017
    Assignee: NEC Corporation
    Inventor: Tadashi Koga
  • Publication number: 20160112155
    Abstract: A signal reception processing apparatus includes a digital signal processing unit that calculates a first Q value based on distribution of the symbols of the demodulated signal and distance between the symbols of the demodulated signal, and an error correction unit that outputs corrected signal as a demodulation electric signal, and calculates a second Q value based on an error rate at the time of the correction, and a control unit that calculates a penalty that indicates degradation quantity of signal quality caused by a nonlinear optical effect of an optical fiber based on the first Q value and the second Q value.
    Type: Application
    Filed: October 19, 2015
    Publication date: April 21, 2016
    Inventor: Tadashi KOGA
  • Patent number: 7991299
    Abstract: An exemplary aspect of the invention is an optical transmitter that emits a light signal, including: a light source; a Mach-Zehnder optical modulator; a modulator driver; a wavelength information holder; and a driving voltage controller, wherein the Mach-Zehnder optical modulator modulates the light intensity of output light from the light source by use of a modulator driving signal, the modulator driver outputs the modulator driving signal according to an input data signal, the wavelength information holder holds wavelength information on the output light of the light source, the driving voltage controller outputs, to the modulator driver, a control signal for setting the latest driving voltage, according to the wavelength information from the wavelength information holder.
    Type: Grant
    Filed: December 26, 2007
    Date of Patent: August 2, 2011
    Assignee: NEC Corporation
    Inventors: Morihiko Ota, Tadashi Koga
  • Patent number: 7860409
    Abstract: An optical receiver includes an optical amplifier configured to amplify an input optical signal and output an amplified optical signal; and a light receiving element configured to convert the amplified optical signal into an electrical signal and output the electrical signal, and the optical amplifier controls an output-level of the amplified optical signal according to a wavelength of the input optical signal.
    Type: Grant
    Filed: August 21, 2007
    Date of Patent: December 28, 2010
    Assignee: NEC Corporation
    Inventors: Masaki Sato, Morihiko Ota, Tadashi Koga
  • Publication number: 20080219680
    Abstract: Disclosed is a optical receiving apparatus including a balanced receiver comprising first and second light receiving elements which receive respective optical signals from first and second ports of a 1-bit delay interferometer, monitor units that monitor amplitudes and delays at the first and second light receiving elements, respectively, control units that variably respectively control attenuations and delays on the paths between the first and second output ports of the 1-bit delay interferometer and the first and second light receiving elements, based on monitored results by the monitor units.
    Type: Application
    Filed: March 5, 2008
    Publication date: September 11, 2008
    Inventors: Kumi Omori, Tadashi Koga
  • Publication number: 20080212982
    Abstract: An optical receiver includes an optical amplifier configured to amplify an input optical signal and output an amplified optical signal; and a light receiving element configured to convert the amplified optical signal into an electrical signal and output the electrical signal, and the optical amplifier controls an output-level of the amplified optical signal according to a wavelength of the input optical signal.
    Type: Application
    Filed: August 21, 2007
    Publication date: September 4, 2008
    Applicant: NEC CORPORATION
    Inventors: Masaki Sato, Morihiko Ota, Tadashi Koga
  • Publication number: 20080212979
    Abstract: An exemplary aspect of the invention is an optical transmitter that emits a light signal, including: a light source; a Mach-Zehnder optical modulator; a modulator driver; a wavelength information holder; and a driving voltage controller, wherein the Mach-Zehnder optical modulator modulates the light intensity of output light from the light source by use of a modulator driving signal, the modulator driver outputs the modulator driving signal according to an input data signal, the wavelength information holder holds wavelength information on the output light of the light source, the driving voltage controller outputs, to the modulator driver, a control signal for setting the latest driving voltage, according to the wavelength information from the wavelength information holder.
    Type: Application
    Filed: December 26, 2007
    Publication date: September 4, 2008
    Inventors: Morihiko Ota, Tadashi Koga
  • Patent number: 7212748
    Abstract: When a PLL circuit is used to extract and recover clock component from an information data signal, where an optical receive signal has been converted into an electrical signal, and to monitor the frequency of a recovered clock, a low frequency section frequency detection circuit having a BPF (band-pass filter) where transmission center frequency has been shifted to higher frequency relative to center frequency of the electrical signal and a high frequency section frequency detection circuit having a BPF where the transmission center frequency has been shifted to lower frequency are provided in parallel. Utilizing a slope on one side of each transmission characteristic of the BPF makes it possible to set detection frequency freely and accurately. Therefore, a frequency detection circuit without using a special device in an optical transmitter/receiver, capable of easily detecting accurate frequency shift of f0±?f or more, and of low price and high performance, can be obtained.
    Type: Grant
    Filed: November 26, 2002
    Date of Patent: May 1, 2007
    Assignee: NEC Corporation
    Inventor: Tadashi Koga
  • Publication number: 20030113122
    Abstract: When a PLL circuit is used to extract and recover clock component from an information data signal, where an optical receive signal has been converted into an electrical signal, and to monitor the frequency of a recovered clock, a low frequency section frequency detection circuit having a BPF (band-pass filter) where transmission center frequency has been shifted to higher frequency relative to center frequency of the electrical signal and a high frequency section frequency detection circuit having a BPF where the transmission center frequency has been shifted to lower frequency are provided in parallel. Utilizing a slope on one side of each transmission characteristic of the BPF makes it possible to set detection frequency freely and accurately. Therefore, a frequency detection circuit without using a special device in an optical transmitter/receiver, capable of easily detecting accurate frequency shift of f0±&Dgr;f or more, and of low price and high performance, can be obtained.
    Type: Application
    Filed: November 26, 2002
    Publication date: June 19, 2003
    Applicant: NEC Corporation
    Inventor: Tadashi Koga
  • Patent number: 6369922
    Abstract: A wavelength division multiplex transmission apparatus capable of transmitting a plurality of 1.55 micron band signal light of different wavelengths by multiplexing the wavelengths is disclosed. A plurality of dispersion compensation units are serially connected, and each executes dispersion compensation with a particular signal light and outputs a respective compensated light. Such signal light output from the dispersion compensation units are combined and then output to a transmission path. Monitor light lying in a 1.3 micron band not susceptible to the operation of an optical direct amplifier is input to the serially connected dispersion compensation units. In each dispersion compensation unit, a photo-detector detects the level of the monitor light. With this configuration, the apparatus is capable of surely detecting faults including the defective connector connection or the shutoff of an optical patch code between the dispersion compensation units.
    Type: Grant
    Filed: November 17, 1998
    Date of Patent: April 9, 2002
    Assignee: NEC Corporation
    Inventor: Tadashi Koga
  • Patent number: 6043922
    Abstract: An optical receiver board wherein, a signal light is amplified in an optical fiber amplifier. The amplified signal light is supplied to an electrically driven optical wavelength-tuning filter such as a multi-layered film interference filter, through which a signal light of a predetermined wavelength bandwidth is transmitted. The transmitted signal light is divided into first and second signal lights. The first signal light is converted to an electric signal which is amplified by an equalizing amplifier, and an amplified electric signal is supplied to a discrimination circuit, in which an information electric signal is generated by using a timing signal. The optical wavelength-tuning filter comprises a rotation actuator having a magnet-rotating portion and control coils, and an optical filter member fixed to the top of the magnet-rotating portion.
    Type: Grant
    Filed: June 3, 1997
    Date of Patent: March 28, 2000
    Assignees: NEC Corporation, Sumitomo Osaka Cement Co., Ltd.
    Inventors: Tadashi Koga, Takaaki Ogata, Hitoshi Oguri, Takashi Nakamura
  • Patent number: 5995254
    Abstract: A wavelength division multiplexing light transmitting system which can monitor its transmission line. In which, one light among the signal lights to be wavelength multiplexed is defined as an optical fiber transmission line monitor light. A transmitter multiplexes and transmits the monitor light with the other signal lights. These lights are attenuated and introduced to the other transmission line at return circuits 12. A receiver branches the returned lights, selects the monitor light and detects a condition of the transmission line by correlation processing. The system extremely improves a SNR and a detection time of the monitor signal.
    Type: Grant
    Filed: January 9, 1997
    Date of Patent: November 30, 1999
    Assignee: NEC Corporation
    Inventors: Tadashi Koga, Yasuhiro Aoki
  • Patent number: 5912754
    Abstract: It is the object of the invention to eliminate a limitation on the transmission distance of a WDM optical transmission system caused by wavelength dependencies of gains of optical amplification repeaters. The transmission characteristic of optical signal of the transmission system against the signal wavelength can be flatted by using plural kinds of the optical amplification repeaters with different gain peak wavelengths, and the longer transmission distance can be obtained.
    Type: Grant
    Filed: October 17, 1996
    Date of Patent: June 15, 1999
    Assignee: NEC Corporation
    Inventors: Tadashi Koga, Yasuhiro Aoki
  • Patent number: 4414196
    Abstract: A method of producing single crystalline, acicular .alpha.-ferric oxide particles of narrow particle size distribution is provided. The method comprises heating an aqueous suspension of ferric hydroxide at temperatures of 100.degree.-250.degree. C. at an alkaline pH in the presence both a water soluble organic or inorganic compound capable of forming complexes with iron as a growth regulating agent and .alpha.-ferric oxide seed crystals of minor axes not larger than 0.4 microns in average in amounts of 0.1-25 mole % in terms of the Fe content thereof in relation to the ferric hydroxide.
    Type: Grant
    Filed: November 18, 1981
    Date of Patent: November 8, 1983
    Assignee: Sakai Chemical Industry Co., Ltd.
    Inventors: Seiji Matsumoto, Tadashi Koga, Kiyoshi Fukai, Hideji Yamamoto
  • Patent number: 4202871
    Abstract: Single crystalline, acicular ferric oxide particles are produced by maintaining an aqueous suspension of ferric hydroxide at an elevated temperature at an alkaline pH in the presence of an organic phosphonic acid compound or a hydroxycarboxylic acid compound as a growth-regulating agent.
    Type: Grant
    Filed: November 6, 1978
    Date of Patent: May 13, 1980
    Assignee: Sakai Chemical Industry Co., Ltd.
    Inventors: Seiji Matsumoto, Tadashi Koga, Kiyoshi Fukai, Shinya Nakatani