Patents by Inventor Hiroshi Maegawa

Hiroshi Maegawa 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: 7016273
    Abstract: The present invention provides an optical pickup device that is resistant to noise in a signal or an RF signal outputted from each light receiving member. Current signals outputted from the light receiving members are converted into voltage signals by I/V converters. The voltage signals are then added up by an adder, and then the added voltage signal is attenuated by an attenuator, so as to obtain an RF signal having the same signal level as the voltage signal outputted from each I/V converter. The RF signal is then transmitted from the optical pickup device to a circuit substrate through a signal line.
    Type: Grant
    Filed: January 16, 2004
    Date of Patent: March 21, 2006
    Assignee: Ricoh Company, Ltd.
    Inventor: Hiroshi Maegawa
  • Publication number: 20060044994
    Abstract: In an optical information record medium including a plurality of record layers that are recordable, various signal characteristics with respect to an area X in a record layer A (second layer) among the plurality of record layers are defined under a condition that an area Y in a record layer B (first layer) adjacent to the record layer A (second layer) on an incident side thereof along an optical axis of a light beam shone on the area X is a prerecorded area. This suppresses variation and errors in the measurement of characteristics of various signals caused by the interfering light coming from an adjacent record layer, thereby making it possible to manage and define media parameters with characteristic values having high reliability, compatibility, and reproducibility.
    Type: Application
    Filed: September 12, 2005
    Publication date: March 2, 2006
    Inventor: Hiroshi Maegawa
  • Publication number: 20050213462
    Abstract: A multi-level information reproducing method for reproducing from a recording medium on which marks having detection signal levels different according to multi-level information are recorded in areas virtually divided uniformly, comprising the steps of: a) obtaining a reproduced signal from a series of patterns of multi-level information indicating an average level of intersymbol interference components to adjacent areas generated from marks according to all the multi-level information; and b) optimizing frequency characteristics of a reproducing part with respect to the reproduced signal.
    Type: Application
    Filed: March 10, 2005
    Publication date: September 29, 2005
    Inventor: Hiroshi Maegawa
  • Publication number: 20050195730
    Abstract: An optical disk includes a recording surface on which a plurality of pits, corresponding to multilevel (three level or higher) information, is formed as a spiral or concentric pit array. The pit array wobbles periodically. A plurality of predetermined reference marks, corresponding to a period of the wobble, are included in the pit array.
    Type: Application
    Filed: February 24, 2005
    Publication date: September 8, 2005
    Inventor: Hiroshi Maegawa
  • Patent number: 6888783
    Abstract: A wobble detection circuit detects a signal by a common photodetector (light receiving) element from several kinds of media having different pre-formats. Further, the wobble detection circuit changes a gain for amplifying the signal in a wobble signal detection process depending on the pre-format of a reproducing or recording medium to obtain a wobble signal.
    Type: Grant
    Filed: March 20, 2002
    Date of Patent: May 3, 2005
    Assignee: Ricoh Company, Ltd.
    Inventor: Hiroshi Maegawa
  • Publication number: 20050065196
    Abstract: The present invention relates to an azole compound represented by the formula [I] wherein W is S or O; R is —COOR7, —X1-A1-COOR7 (R7 is H, alkyl) or tetrazolyl; R1, R2, R3 and R4 are H and the like; A is —(CH2)m—X— (X is —N(R8)—, —C(R9)(R10)—, —CO— or —CO—N(R8)—); B is aryl or aromatic heterocyclic group; R5 is H and the like; R6 is —(Y)s1-(A2)s-Z (Y is —O—, —S(O)t—, —N(R13)—, —N(R14)—CO—, —N(R14)—SO2—, —SO2—N(R14)— and the like, A2 is alkylene, and Z is cycloalkyl, aryl, aromatic heterocyclic group, indanyl, piperazinyl, a prodrug thereof or a pharmaceutically acceptable salt thereof. The compound [I] of the present invention has a protein tyrosine phosphatase 1B inhibitory activity, and is useful as a therapeutic agent for diabetes, a therapeutic drug for diabetic complications or a therapeutic drug for hyperlipidemia.
    Type: Application
    Filed: December 3, 2002
    Publication date: March 24, 2005
    Inventors: Takashi Inaba, Tomoyuki Ikemoto, Shohei Sakata, Hiroshi Maegawa, Atsunori Kashiwagi
  • Patent number: 6859425
    Abstract: An wobble signal detection circuit that is provided on an optical disk device and can detect a wobble signal having high accuracy and stability at least when recording information on an optical disk. This wobble signal detection circuit can be applied to plural types of optical recording media. With the wobble signal detection circuit, during a period for forming a space region, a first voltage signal provided from a first light receiving element is sampled and amplified to be a target voltage, a second voltage signal provided from a second light receiving element is sampled and amplified to be the target voltage. The difference between the two amplified signals are output as the wobble signal. The first and second light receiving elements are divided from each other in the direction tangential to a recording region on the optical recording medium.
    Type: Grant
    Filed: December 6, 2002
    Date of Patent: February 22, 2005
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiroshi Maegawa, Toshihiro Shigemori
  • Publication number: 20040146000
    Abstract: The present invention provides an optical pickup device that is resistant to noise in a signal or an RF signal outputted from each light receiving member. Current signals outputted from the light receiving members are converted into voltage signals by I/V converters. The voltage signals are then added up by an adder, and then the added voltage signal is attenuated by an attenuator, so as to obtain an RF signal having the same signal level as the voltage signal outputted from each I/V converter. The RF signal is then transmitted from the optical pickup device to a circuit substrate through a signal line.
    Type: Application
    Filed: January 16, 2004
    Publication date: July 29, 2004
    Inventor: Hiroshi Maegawa
  • Patent number: 6741540
    Abstract: The present invention provides an optical pickup device that is resistant to noise in a signal or an RF signal outputted from each light receiving member. Current signals outputted from the light receiving members are converted into voltage signals by I/V converters. The voltage signals are then added up by an adder, and then the added voltage signal is attenuated by an attenuator, so as to obtain an RF signal having the same signal level as the voltage signal outputted from each I/V converter. The RF signal is then transmitted from the optical pickup device to a circuit substrate through a signal line.
    Type: Grant
    Filed: December 15, 2000
    Date of Patent: May 25, 2004
    Assignee: Ricoh Company, Ltd.
    Inventor: Hiroshi Maegawa
  • Publication number: 20040052177
    Abstract: A multilevel information recording apparatus is disclosed, which includes a control unit that inputs signals to a strategy generating unit and a laser drive unit based on the multilevel information being recorded, a signal indicating the playback and recording state, and a clock signal indicating the cell frequency that is in synch with the multilevel information. The strategy generating unit generates a pulse signal in accordance with the timing of the laser beam emission of a write pulse, an off pulse, a bias pulse, and a space pulse based on the signal from the control unit and the clock signal. The laser drive unit determines the driving current of a laser light source based on a delayed playback signal/delayed recording signal that is obtained by delaying the playback signal/recording signal for a processing time of the strategy generating unit, a pulse signal from the strategy generating unit indicating the emission timing of the pulses, and an intensity signal predetermined for each pulse.
    Type: Application
    Filed: August 29, 2003
    Publication date: March 18, 2004
    Inventor: Hiroshi Maegawa
  • Publication number: 20040013063
    Abstract: A wobble detection circuit detects a signal by a common photodetector (light receiving) element from several kinds of media having different pre-formats. Further, the wobble detection circuit changes a gain for amplifying the signal in a wobble signal detection process depending on the pre-format of a reproducing or recording medium to obtain a wobble signal.
    Type: Application
    Filed: August 15, 2003
    Publication date: January 22, 2004
    Inventor: Hiroshi Maegawa
  • Publication number: 20030128641
    Abstract: An wobble signal detection circuit that is provided on an optical disk device and can detect a wobble signal having high accuracy and stability at least when recording information on an optical disk. This wobble signal detection circuit can be applied to plural types of optical recording media. With the wobble signal detection circuit, during a period for forming a space region, a first voltage signal provided from a first light receiving element is sampled and amplified to be a target voltage, a second voltage signal provided from a second light receiving element is sampled and amplified to be the target voltage. The difference between the two amplified signals are output as the wobble signal. The first and second light receiving elements are divided from each other in the direction tangential to a recording region on the optical recording medium.
    Type: Application
    Filed: December 6, 2002
    Publication date: July 10, 2003
    Inventors: Hiroshi Maegawa, Toshihiro Shigemori
  • Publication number: 20020136126
    Abstract: A wobble detection circuit detects a signal by a common photodetector (light receiving) element from several kinds of media having different pre-formats. Further, the wobble detection circuit changes a gain for amplifying the signal in a wobble signal detection process depending on the pre-format of a reproducing or recording medium to obtain a wobble signal.
    Type: Application
    Filed: March 20, 2002
    Publication date: September 26, 2002
    Inventor: Hiroshi Maegawa
  • Patent number: 6345018
    Abstract: A device for demodulating position information that is recorded as track wobbling in a record medium by a BPSK scheme includes a carrier-wave-generation circuit which derives a carrier wave from a wobbling signal obtained from the record medium, a phase-adjustment circuit which generates a phase-comparison signal having a 90° phase difference relative to the carrier wave, a multiplier which multiplies the wobbling signal and the phase-comparison signal to supply a product signal, and a detection circuit which detects a phase error of the carrier wave introduced by the carrier-wave-generation circuit by detecting the phase error between the wobbling signal and the phase-comparison signal based on the product signal.
    Type: Grant
    Filed: August 4, 2000
    Date of Patent: February 5, 2002
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiroshi Maegawa, Toshihiro Shigemori
  • Publication number: 20010005354
    Abstract: The present invention provides an optical pickup device that is resistant to noise in a signal or an RF signal outputted from each light receiving member. Current signals outputted from the light receiving members are converted into voltage signals by I/V converters. The voltage signals are then added up by an adder, and then the added voltage signal is attenuated by an attenuator, so as to obtain an RF signal having the same signal level as the voltage signal outputted from each I/V converter. The RF signal is then transmitted from the optical pickup device to a circuit substrate through a signal line.
    Type: Application
    Filed: December 15, 2000
    Publication date: June 28, 2001
    Inventor: Hiroshi Maegawa
  • Patent number: 6160773
    Abstract: An optical disk device performs tracking on a recordable optical disk which has an information recording track and a guiding track for guiding an optical beam to the information recording track, the guiding track having pre-pits including address information recorded therein. This device includes a photodetector which is divided into two divisions by a dividing line which is approximately optically parallel to the tangential line of the information recording track of the optical disk, and receives reflected light of the optical beam which is incident on the information recording track, and a tracking-error-signal generating portion having the respective outputs of the two divisions of the photodetector input thereto and generating a tracking error signal which is used for performing the tracking on the optical disk.
    Type: Grant
    Filed: September 23, 1998
    Date of Patent: December 12, 2000
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiroshi Maegawa, Masahiko Nakayama
  • Patent number: 5956313
    Abstract: A trial writing operation is performed on a phase-change optical disc using write and erase light-emitting powers, which together are varied according to predetermined variation ratios respectively. Signals relevant to said trial writing operation are reproduced from said disc. Optimum ones of the write and erase light-emitting powers are determined using the thus-reproduced signals. The predetermined variation ratios for the write and erase light-emitting powers may be the same as each other. Alternatively, the trial writing operation may be performed on a phase-change optical disc using write and erase light-emitting powers which are individually varied according to predetermined variation ratios respectively.
    Type: Grant
    Filed: March 5, 1997
    Date of Patent: September 21, 1999
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiroshi Maegawa, Ikuo Aoki
  • Patent number: 5828634
    Abstract: An optical disk device includes an optical system having a beam converting unit and an objective lens. The beam converting unit converts a beam of laser light emitted by a laser light source into a main beam and at least one sub-beam. The objective lens places a main spot on the disk by the main beam and at least one sub-spot on the disk by the sub-beam, such that, when the main spot is on a center line of one of lands and grooves of an optical disk, the sub-spot is between the center line of one of the lands and the grooves and a center line of an adjacent one of the lands and the grooves. A first unit produces a first push-pull signal from a reflection beam from the main spot on the disk. A second unit produces a second push-pull signal from a reflection beam from the sub-spot on the disk. A tracking error signal generating unit produces a tracking error signal based upon the first push-pull signal.
    Type: Grant
    Filed: February 20, 1997
    Date of Patent: October 27, 1998
    Assignee: Ricoh Company, Ltd.
    Inventors: Takehide Ohno, Hiroshi Maegawa
  • Patent number: 5745463
    Abstract: A trial writing operation is performed on a phase-change optical disc using write and erase light-emitting powers, which together are varied according to predetermined variation ratios respectively. Signals relevant to said trial writing operation are reproduced from said disc. Optimum ones of the write and erase light-emitting powers are determined using the thus-reproduced signals. The predetermined variation ratios for the write and erase light-emitting powers may be the same as each other. Alternatively, the trial writing operation may be performed on a phase-change optical disc using write and erase light-emitting powers which are individually varied according to predetermined variation ratios respectively.
    Type: Grant
    Filed: March 5, 1997
    Date of Patent: April 28, 1998
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiroshi Maegawa, Ikuo Aoki
  • Patent number: 5648952
    Abstract: A trial writing operation is performed on a phase-change optical disc using write and erase light-emitting powers, which together are varied according to predetermined variation ratios respectively. Signals relevant to said trial writing operation are reproduced from said disc. Optimum ones of the write and erase light-emitting powers are determined using the thus-reproduced signals. The predetermined variation ratios for the write and erase light-emitting powers may be the same as each other. Alternatively, the trial writing operation may be performed on a phase-change optical disc using write and erase light-emitting powers which are individually varied according to predetermined variation ratios respectively.
    Type: Grant
    Filed: September 26, 1995
    Date of Patent: July 15, 1997
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiroshi Maegawa, Ikuo Aoki