Patents by Inventor Kunikazu Ohnishi
Kunikazu Ohnishi 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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Patent number: 7965594Abstract: When recording/reproducing an optical disc having a recording layer of multi-layer structure, an unwanted optical beam reflected from a recording layer other than a target layer for recording/reproduction is incident on a photodetector to cause an unwanted disturbance component to leak to a detection signal, giving rise to a degradation in the quality of a tracking control signal. In an optical pickup apparatus, for suppression of the degradation, an optical element is mounted having a diffraction area for diffracting part of the optical beam and light receiving planes for sub-optical beams are provided each of which has a light shielding zone or dead zone of a predetermined width on its central sectioning line.Type: GrantFiled: June 30, 2010Date of Patent: June 21, 2011Assignee: Hitachi Media Electronics Co., Ltd.Inventors: Toshiteru Nakamura, Shigeharu Kimura, Kunikazu Ohnishi, Toshio Sugiyama
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Patent number: 7936658Abstract: The present invention provides a photodetector capable of generating highly accurate tracking and focusing error signals free of variations in light quantity caused by interference, in an optical pickup with a two-wavelength multilaser. The photodetector comprises first three light receiving areas arranged linearly to receive three light beams respectively resulting from splitting of a light beam emitted from a laser light source of a first wavelength and second three light receiving areas arranged linearly to receive three light beams respectively resulting from splitting of a light beam emitted from a laser light source of a second wavelength longer than the first wavelength. The distance between both-end light receiving areas out of the first three light receiving areas is longer than the distance between both-end light receiving areas out of the second three light receiving areas.Type: GrantFiled: February 22, 2010Date of Patent: May 3, 2011Assignee: Hitachi Media Electronics Co., Ltd.Inventors: Tomoto Kawamura, Kunikazu Ohnishi, Masayuki Inoue, Katsuhiko Izumi
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Patent number: 7911915Abstract: An optical pickup includes a diffraction grating partitioned into three areas, in which the phase of periodic grating groove structure in an area is successively shifted from that in the adjacent area by 90°. In the generation of a differential push-pull signal, an amplification factor K for sub push-pull signals is varied depending on the type of the optical disk. By such composition of the optical pickup, amplitude deterioration of the tracking error signal accompanying displacement of the object lens is reduced.Type: GrantFiled: October 2, 2007Date of Patent: March 22, 2011Assignees: Hitachi Ltd., Hitachi Media Electronics Co., Ltd.Inventors: Kunikazu Ohnishi, Tomoto Kawamura, Masayuki Inoue
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Publication number: 20100322047Abstract: When recording/reproducing an optical disc having a recording layer of multi-layer structure, an unwanted optical beam reflected from a recording layer other than a target layer for recording/reproduction is incident on a photodetector to cause an unwanted disturbance component to leak to a detection signal, giving rise to a degradation in the quality of a tracking control signal. In an optical pickup apparatus, for suppression of the degradation, an optical element is mounted having a diffraction area for diffracting part of the optical beam and light receiving planes for sub-optical beams are provided each of which has a light shielding zone or dead zone of a predetermined width on its central sectioning line.Type: ApplicationFiled: June 30, 2010Publication date: December 23, 2010Inventors: Toshiteru NAKAMURA, Shigeharu Kimura, Kunikazu Ohnishi, Toshio Sugiyama
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Publication number: 20100226229Abstract: In a multilayer disc has an increased number of recording layers) spaced by spacing from each other, a generation interval between focus error (FE) signals detected from the respective recording layers becomes small. This causes mutual interference between the FE signals and a resulting undesired offset and the like in the signals, leading to a significantly deteriorated quality of the FE signals. To avoid this, in an optical pickup device according to the present invention, detection surfaces are newly added at positions adjacent to the FE signal detection surfaces, a predetermined detection signal obtained from the newly-added detection surfaces is multiplied by a predetermined coefficient value depending on the spacing between the recording layers, and the multiplied signal is subtracted from the original FE signal. As a result, mutual interference between the FE signals can be remarkably reduced.Type: ApplicationFiled: October 29, 2009Publication date: September 9, 2010Inventors: Kunikazu OHNISHI, Kazuyoshi Yamazaki
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Publication number: 20100148045Abstract: The present invention provides a photodetector capable of generating highly accurate tracking and focusing error signals free of variations in light quantity caused by interference, in an optical pickup with a two-wavelength multilaser. The photodetector comprises first three light receiving areas arranged linearly to receive three light beams respectively resulting from splitting of a light beam emitted from a laser light source of a first wavelength and second three light receiving areas arranged linearly to receive three light beams respectively resulting from splitting of a light beam emitted from a laser light source of a second wavelength longer than the first wavelength. The distance between both-end light receiving areas out of the first three light receiving areas is longer than the distance between both-end light receiving areas out of the second three light receiving areas.Type: ApplicationFiled: February 22, 2010Publication date: June 17, 2010Inventors: Tomoto KAWAMURA, Kunikazu Ohnishi, Masayuki Inoue, Katsuhiko Izumi
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Patent number: 7724626Abstract: An optical pickup includes a diffraction grating partitioned into three areas, in which the phase of periodic grating groove structure in an area is successively shifted from that in the adjacent area by 90°. In the generation of a differential push-pull signal, an amplification factor K for sub push-pull signals is varied depending on the type of the optical disk. By such composition of the optical pickup, amplitude deterioration of the tracking error signal accompanying displacement of the object lens is reduced.Type: GrantFiled: October 2, 2007Date of Patent: May 25, 2010Assignees: Hitachi, Ltd., Hitachi Media Electronics Co., Ltd.Inventors: Kunikazu Ohnishi, Tomoto Kawamura, Masayuki Inoue
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Publication number: 20100124153Abstract: An optical pickup and an optical information recording and reproducing device in which spherical aberration correction control after a disc is loaded can be efficiently made in a short time. Before an information recording medium is loaded into a drive, an optical axis direction position of a concave lens is preset to a state so as to optimize a converging spot on a recording surface of a single-layered medium of as a first recording medium or a predetermined layer (first layer having a substrate thickness of 0.1 mm) of a medium having two or more layers to which the recording/reproduction is executed by a laser light source. After the information recording medium is loaded, if it is determined to be a second (third) recording medium to which the recording/reproduction is executed by a laser light source, setting of the optical axis direction position of the concave lens is changed.Type: ApplicationFiled: January 25, 2010Publication date: May 20, 2010Applicant: Hitachi Media Electronics Co., Ltd.Inventors: Hiromitsu MORI, Kunikazu Ohnishi, Nobuyuki Maeda, Masayuki Inoue
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Publication number: 20100124161Abstract: An optical pickup and an optical information recording and reproducing device in which spherical aberration correction control after a disc is loaded can be efficiently made in a short time. Before an information recording medium is loaded into a drive, an optical axis direction position of a concave lens is preset to a state so as to optimize a converging spot on a recording surface of a single-layered medium of as a first recording medium or a predetermined layer (first layer having a substrate thickness of 0.1 mm) of a medium having two or more layers to which the recording/reproduction is executed by a laser light source. After the information recording medium is loaded, if it is determined to be a second (third) recording medium to which the recording/reproduction is executed by a laser light source, setting of the optical axis direction position of the concave lens is changed.Type: ApplicationFiled: January 25, 2010Publication date: May 20, 2010Applicant: Hitachi Media Electronics Co., Ltd.Inventors: Hiromitsu MORI, Kunikazu Ohnishi, Nobuyuki Maeda, Masayuki Inoue
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Patent number: 7715298Abstract: An optical pickup module with enhanced aberration correctability is disclosed. This pickup includes more than two different types of laser light sources, an objective lens for collecting and focusing any one of the laser beams leaving the light sources onto an optical disc, and an aberration correction device of the liquid crystal (LC) type, which is disposed between the light sources and the objective lens. The aberration corrector has a surface on which multiple spaced-apart electrodes are patterned for enabling aberration correction relative to incident beams. The corrector controls the potential of a voltage being applied to each electrode in deference to incident beam properties and variations occurrable thereto, e.g., wavelength, effective beam diameter and relative incidence position offsets, thereby to optimally correct beam aberrations, such as coma aberration or wavefront aberration. An optical information reproduction apparatus using the pickup is also disclosed.Type: GrantFiled: August 24, 2006Date of Patent: May 11, 2010Assignee: Hitachi Media Electronics Co., Ltd.Inventor: Kunikazu Ohnishi
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Patent number: 7706220Abstract: The present invention provides a photodetector capable of generating highly accurate tracking and focusing error signals free of variations in light quantity caused by interference, in an optical pickup with a two-wavelength multilaser. The photodetector comprises first three light receiving areas arranged linearly to receive three light beams respectively resulting from splitting of a light beam emitted from a laser light source of a first wavelength and second three light receiving areas arranged linearly to receive three light beams respectively resulting from splitting of a light beam emitted from a laser light source of a second wavelength longer than the first wavelength. The distance between both-end light receiving areas out of the first three light receiving areas is longer than the distance between both-end light receiving areas out of the second three light receiving areas.Type: GrantFiled: March 7, 2006Date of Patent: April 27, 2010Assignee: Hitachi Media Electronics Co., Ltd.Inventors: Tomoto Kawamura, Kunikazu Ohnishi, Masayuki Inoue, Katsuhiko Izumi
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Patent number: 7697394Abstract: An optical pickup includes a diffraction grating partitioned into three areas, in which the phase of periodic grating groove structure in an area is successively shifted from that in the adjacent area by 90°. In the generation of a differential push-pull signal, an amplification factor K for sub push-pull signals is varied depending on the type of the optical disk. By such composition of the optical pickup, amplitude deterioration of the tracking error signal accompanying displacement of the object lens is reduced.Type: GrantFiled: October 2, 2007Date of Patent: April 13, 2010Assignees: Hitachi, Ltd., Hitachi Media Electronics Co., Ltd.Inventors: Kunikazu Ohnishi, Tomoto Kawamura, Masayuki Inoue
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Patent number: 7697393Abstract: An optical pickup includes a diffraction grating partitioned into three areas, in which the phase of periodic grating groove structure in an area is successively shifted from that in the adjacent area by 90°. In the generation of a differential push-pull signal, an amplification factor K for sub push-pull signals is varied depending on the type of the optical disk. By such composition of the optical pickup, amplitude deterioration of the tracking error signal accompanying displacement of the object lens is reduced.Type: GrantFiled: October 2, 2007Date of Patent: April 13, 2010Assignees: Hitachi, Ltd., Hitachi Media Electronics Co., Ltd.Inventors: Kunikazu Ohnishi, Tomoto Kawamura, Masayuki Inoue
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Publication number: 20100034071Abstract: Undesired disturbance components leak eventually into various detection signals and reproduction signals as stray optical beams reflected from recording layers other than a reproduction layer overlap with signal beams on a light reception surface of an optical detector and interference occurs between them when an optical disc having multi-layered recording layers is reproduced. A diffraction grating having a specific grating groove pattern is arranged immediately ahead of an optical detector or in a return optical path. Such optical unit averages the disturbance components resulting from interference between a signal beam and a stray beam and can satisfactorily improve influences of leak.Type: ApplicationFiled: April 2, 2009Publication date: February 11, 2010Inventor: Kunikazu OHNISHI
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Patent number: 7656771Abstract: An optical pickup for writing information to and/or for reading information from an optical disc having at least two recording layers (dual layer) provided with first and second recording layers can prevent layer crosstalk resulting from disturbing a signal reproduced from the first recording layer by a reflected light beam reflected from the second recording layer during a writing operation for writing information to the first recording layer or a reading operation for reading information from the fist recording layer. An orthogonal polarization region forming component forms an orthogonal polarization region, in which respective directions of polarization of a first light beam focused on and reflected by a first recording layer of an optical disc and a second light beam reflected by a second recording layer of the optical disc are perpendicular to each other, in a region, in which the first and the second light beam overlap each other, on a light-receiving surface of a detector.Type: GrantFiled: August 22, 2006Date of Patent: February 2, 2010Assignee: Hitachi Media Electronics Co., Ltd.Inventors: Kenichi Shimada, Kunikazu Ohnishi, Nobuhiro Konuma
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Patent number: 7590043Abstract: An optical pickup includes a diffraction grating partitioned into three areas, in which the phase of periodic grating groove structure in an area is successively shifted from that in the adjacent area by 90°. In the generation of a differential push-pull signal, an amplification factor K for sub push-pull signals is varied depending on the type of the optical disk. By such composition of the optical pickup, amplitude deterioration of the tracking error signal accompanying displacement of the object lens is reduced.Type: GrantFiled: October 2, 2007Date of Patent: September 15, 2009Assignees: Hitachi, Ltd., Hitachi Media Electronics Co., Ltd.Inventors: Kunikazu Ohnishi, Tomoto Kawamura, Masayuki Inoue
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Publication number: 20090129217Abstract: A rewritable optical disk apparatus, optical information recording and reproducing apparatus or the like is allowed to automatically and properly adjust the optical system to the optimum focal condition regardless of the readout signal detector's positional error and the residual aberration in the optical system. The spherical aberration and defocus are coarsely adjusted using the amplitude (PP amplitude) of the tracking error signal and then finely adjusted using the amplitude (RF amplitude) of the readout signal. Since the spherical aberration can properly be adjusted, it is possible to raise the reliability of the readout signal.Type: ApplicationFiled: January 16, 2009Publication date: May 21, 2009Inventors: Fumio ISSHIKI, Kunikazu Ohnishi, Nobuyuki Maeda, Takahiro Kurokawa, Takeshi Shimano
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Patent number: 7480216Abstract: A rewritable optical disk apparatus, optical information recording and reproducing apparatus or the like is allowed to automatically and properly adjust the optical system to the optimum focal condition regardless of the readout signal detector's positional error and the residual aberration in the optical system. The spherical aberration and defocus are coarsely adjusted using the amplitude (PP amplitude) of the tracking error signal and then finely adjusted using the amplitude (RF amplitude) of the readout signal. Since the spherical aberration can properly be adjusted, it is possible to raise the reliability of the readout signal.Type: GrantFiled: June 30, 2004Date of Patent: January 20, 2009Assignee: Hitachi Media Electronics Co., Ltd.Inventors: Fumio Isshiki, Kunikazu Ohnishi, Nobuyuki Maeda, Takahiro Kurokawa, Takeshi Shimano
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Publication number: 20080219119Abstract: Provided is an optical pickup which can eliminate a problem of causing a focus error signal and a tracking error signal to fluctuate due to interference of a signal light beam with a return light beam from another recording surface of a multi-layer optical disc during reproduction, comprising: a laser source for emitting an optical beam, an objective lens for focusing the light beam onto the multi-layer optical disc, a polarizing grating located at a position through which a reflected light beam from the multi-layer optical disc passes, for branching the reflected beam into at least two light beams, that is, a 0-order light beam and a +1-order light beam having a direction of polarization which is orthogonal to that of the 0-order light beam, an optical detector for receiving the two light beams, a first light receiving zone which is provided in the optical detector, and onto which the 0-order light is irradiated, and a second light receiving zone which is provided in the optical detector and onto which the +Type: ApplicationFiled: March 7, 2008Publication date: September 11, 2008Applicant: Hitachi Media Electronics Co., Ltd.Inventors: Katsuhiko Izumi, Kazuyoshi Yamazaki, Tomoto Kawamura, Kunikazu Ohnishi
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Publication number: 20080031119Abstract: An optical pickup includes a diffraction grating partitioned into three areas, in which the phase of periodic grating groove structure in an area is successively shifted from that in the adjacent area by 90°. In the generation of a differential push-pull signal, an amplification factor K for sub push-pull signals is varied depending on the type of the optical disk. By such composition of the optical pickup, amplitude deterioration of the tracking error signal accompanying displacement of the object lens is reduced.Type: ApplicationFiled: October 2, 2007Publication date: February 7, 2008Applicants: HITACHI, LTD., HITACHI MEDIA ELECTRONICS CO., LTD.Inventors: Kunikazu Ohnishi, Tomoto Kawamura, Masayuki Inoue