Patents by Inventor Tadashi Takeda

Tadashi Takeda 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: 6445671
    Abstract: An optical pickup device includes a semiconductor laser for emitting forward and backward laser light from front and back emergent end faces thereof, focusing device for focusing the forward laser light emergent from the front emergent end face of said semiconductor laser onto an optical recording medium, a light-receiving element for signal reproduction for detecting return light from the optical recording medium, and a light-guiding system for guiding the return light to said light-receiving element for signal reproduction, said optical pickup device being provided with a light source unit having an arrangement in which said semiconductor laser and said light-receiving element for signal reproduction being incorporated in a common package and shielding device, disposed inside said package of said light source unit, for preventing the light emitted from said semiconductor laser from being incident upon said light-receiving element for signal reproduction.
    Type: Grant
    Filed: June 30, 1999
    Date of Patent: September 3, 2002
    Assignee: Kabushiki Kaisha Sankyo Seiki Seisakusho
    Inventors: Tadashi Takeda, Hisahiro Ishihara, Yoshio Hayashi, Taminori Masuzawa, Yuichi Takei
  • Patent number: 6438075
    Abstract: A returning light beam from an optical disc is divided by a separating diffractor in the directions perpendicular to a track direction of the optical recording medium, and according to respective illuminances of the divided light beams, a deviation amount of an objective lens to an optical axis is detected. By feedback-controlling an objective lens driver by using the information of the detected deviation amount, the objective lens can be made to become stationary at the desired position in a short time. Accordingly, a time period required for the oscillation attenuation of the objective lens can be shortened, thereby, a time period for the reproduction can be shortened.
    Type: Grant
    Filed: December 2, 1999
    Date of Patent: August 20, 2002
    Assignee: Kabushiki Kaisha Sankyo Seiki Seisakusho
    Inventors: Tadashi Takeda, Yoshio Hayashi, Taminori Masuzawa
  • Publication number: 20020060846
    Abstract: In a diffraction element, a diffraction grating is formed with a grating pitch having different diffraction angles in accordance with a wavelength of a laser light beam incident thereon. The wavelength is variable in accordance with an environment temperature. The diffraction element is made of a material having a linear expansion coefficient which causes thermal variation in the grating pitch enough to compensate at least a part of the diffraction angle variation due to environment temperature change.
    Type: Application
    Filed: October 5, 2001
    Publication date: May 23, 2002
    Applicant: KABUSHIKI KAISHA SANKYO SEIKI SEISAKUSHO
    Inventors: Kenichi Hayashi, Tadashi Takeda
  • Publication number: 20020051421
    Abstract: The present invention provides for a optical head device having a beam-guiding optical device to bring beams of different wavelengths which are emitted by separate light sources together onto the same optical axis or to guide the beams onto a common photo receiving device. The beam-guiding optical device includes an incident plane and an exit plane and the incident plane and the exit plane are back to back. One of the incident plane and the exit plane has a stair-like surface wherein a step height between neighboring treads in the stair-like surface is set to cause a phase difference of n wavelength to one of the beams passing through the neighboring treads and n is equal to 1, 2, 3 . . . .
    Type: Application
    Filed: July 6, 2001
    Publication date: May 2, 2002
    Inventor: Tadashi Takeda
  • Publication number: 20020002228
    Abstract: A flame retardant polyamide resin composition having excellent mechanical strength and tracking resistance. The flame retardant polyamide resin composition comprises (A) 100 parts by weight of polyamide resin, (B) from 1 to 20 parts by weight of melamine cyanurate and (C) from 5 to 120 parts by weight of a whisker comprising a metal borate.
    Type: Application
    Filed: April 16, 1998
    Publication date: January 3, 2002
    Inventors: TADASHI TAKEDA, HIROSHI KIRIKOSHI
  • Publication number: 20010022690
    Abstract: In an optical pickup device, a first light source and a second light source, light emission points of which are not on an identical optical axis, are provided. A first laser light beam and a second laser light beam, wavelengths of which are different from each other, are respectively emitted from the first and second light sources. The first and second laser light-beams reflected from an optical recording medium are diffracted based on different diffraction order, such that the diffracted first and second laser light beams are received by a common light receiving element.
    Type: Application
    Filed: March 12, 2001
    Publication date: September 20, 2001
    Inventor: Tadashi Takeda
  • Patent number: 6204314
    Abstract: The object is to provide a flame retardant polyamide resin composition having excellent tensile elongation at break and excellent properties for use as a hinge. A flame retardant polyamide resin composition is provided, which comprises 100 parts by weight of a polyamide resin mixture consisting of a first aliphatic polyamide and at least one polyamide selected from the group consisting of a second aliphatic polyamide, which differs from the first aliphatic polyamide, and a semi-aromatic polyamide, and from 0.4 to 20 parts by weight of a melamine cyanurate-type flame retarder.
    Type: Grant
    Filed: June 7, 1999
    Date of Patent: March 20, 2001
    Assignee: EC-Showa Denko K.K.
    Inventors: Tadashi Takeda, Toshihiro Arai, Osamu Hamazoe, Hiroshi Kirikoshi
  • Patent number: 6184512
    Abstract: A semiconductor laser apparatus comprises a semiconductor substrate, a semiconductor laser which is fixed on the semiconductor substrate and a prism having a slanted plane. The prism is placed such that its slanted plane faces a side across from the semiconductor laser. The apparatus also includes an optical detector for monitoring which is formed on the surface of the semiconductor substrate. The surface is covered by the prism. The following are formed on the slanted plane of the prism: a reflection region on which the surface is processed for reflecting a part of an emitted light beam from the semiconductor laser and a transmissive refraction region on which the surface is processed such that the remaining part of the emitted light beam is transmitted and refracted to be guided to a light receiving plane of the optical detector for monitoring.
    Type: Grant
    Filed: May 20, 1998
    Date of Patent: February 6, 2001
    Assignee: Sankyo Seiki Mfg. Co., Ltd.
    Inventors: Kazuo Higashiura, Yoshio Hayashi, Tadashi Takeda
  • Patent number: 6167017
    Abstract: In accordance with the invention, an optical head assembly comprises a laser light source, an objective lens for converging light emitted from the laser light source onto an recording surface of an optical recording medium, an optical detector device for detecting the light reflected upon the recording surface, a modulating diffraction grating for splitting the light emitted from the laser light source into 0th-order beam, +1st-order beam and -1st-order beam in a track direction of the recording surface, emitting the three beams toward the center of the track of the recording surface, and causing, with respect to the +1st-order beam and -1st-order beam, astigmatisms of different focal points in a direction orthogonal to the track direction, and a light-guiding device for guiding three returning beams reflected from the recording surface to the optical detector device.
    Type: Grant
    Filed: May 14, 1998
    Date of Patent: December 26, 2000
    Assignee: Sankyo Seiki Mfg. Co., Ltd.
    Inventors: Kazuo Higashiura, Tadashi Takeda
  • Patent number: 6151288
    Abstract: An optical head assembly comprises a laser light source, an objective lens for converging a laser light emitted from the laser light source on an optical recording medium, an optical detector for detecting a returning light from the optical recording medium, a diffraction unit mounted in an optical path between the laser light source and objective lens for positioning multiple diffraction grating means, a base of the optical head assembly for supporting the objective lens, the laser light source and the optical detector, and a diffraction grating unit retaining portion formed on the base for holding the diffraction grating unit.
    Type: Grant
    Filed: July 14, 1998
    Date of Patent: November 21, 2000
    Assignee: Sankyo Seiki Mfg. Co., Ltd.
    Inventors: Yuichi Takei, Tadashi Takeda, Yoshio Hayashi
  • Patent number: 6084844
    Abstract: An optical head assembly comprises a laser light source, an objective lens for converging laser light rays emitted from the laser light source at an optical recording medium, a hologram element placed in the optical path between the laser light source and the objective lens, an optical detector for signaling that detects returning light rays from the optical recording medium and an optical detector for monitoring that detects a portion of the laser beams emitted from the laser source toward the optical recording medium. The hologram element has first and second diffraction areas; the first diffraction area diffracting the returning light rays to guide them to the optical detector for signaling; the second diffraction area reflecting and diffracting a portion of the light rays emitted from the laser light source at a fringe-like reflecting portion to guide them to the optical detector for monitoring.
    Type: Grant
    Filed: March 20, 1998
    Date of Patent: July 4, 2000
    Assignee: Sankyo Seiki Mfg.Co., Ltd.
    Inventor: Tadashi Takeda
  • Patent number: 6016300
    Abstract: An optical pickup head apparatus for reading information signals from a recording medium having a laser beam light source, an objective lens and a photodetector, the improvement comprises a holographic optical element constructed of a pair of diffraction gratings having different diffractive conditions wherein the element is split into two by a split line near its optical axis as a border and a diffraction generation prevention device for preventing the generation of unwanted diffracted beams from a recording medium. The optical pickup head apparatus irradiates a laser beam emitted from the light source onto a recording medium via the holographic optical element and the objective lens. Beams reflected from the recording medium are guided to the photodetector via the objective lens and the holographic optical element.
    Type: Grant
    Filed: July 13, 1998
    Date of Patent: January 18, 2000
    Assignee: Sankyo Seiki Mfg. Co., Ltd.
    Inventors: Tadashi Takeda, Yoshio Hayashi, Hideo Takezoe, Ken Ishikawa
  • Patent number: 5828643
    Abstract: An optical pickup head apparatus for reading information signals from a recording medium having a laser beam light source, an objective lens and a photodetector, the improvement comprises a holographic optical element constructed of a pair of diffraction gratings having different diffractive conditions wherein the element is split into two by a split line near its optical axis as a border and a diffraction generation prevention device for preventing the generation of unwanted diffracted beams from a recording medium. The optical pickup head apparatus irradiates a laser beam emitted from the light source onto a recording medium via the holographic optical element and the objective lens. Beams reflected from the recording medium are guided to the photodetector via the objective lens and the holographic optical element.
    Type: Grant
    Filed: June 19, 1996
    Date of Patent: October 27, 1998
    Assignee: Sankyo Seiki Mfg. Co., Ltd.
    Inventors: Tadashi Takeda, Yoshio Hayashi, Hideo Takezoe, Ken Ishikawa
  • Patent number: 5793733
    Abstract: A polarizing beam-splitter comprises an optically isotropics crystalline substrate and a birefringent material layer made of an oriented polydiacetylene film formed on the optically isotropic crystalline substrate. A periodic grating photo-mask is formed in the birefringent material layer by an area that is changed into a different color phase when an ultra violet light is irradiated in a predetermined pattern on the birefringent material layer and by an area in which the color remains unchanged. The periodic grating photo-mask has a diffraction efficiency for the orientation of the oriented polydiacetylene film in the area that is changed into a different color phase which is lower than that in the area in which the color is unchanged.
    Type: Grant
    Filed: August 23, 1996
    Date of Patent: August 11, 1998
    Assignee: Sankyo Seiki Mfg. Co., Ltd.
    Inventors: Tadashi Takeda, Yoshio Hayashi, Satoru Nakao, Hideo Takezoe, Ken Ishikawa, Takaaki Suzuki, Atsuo Fukuda
  • Patent number: 5761174
    Abstract: An optical pickup device includes a light source irradiating a record medium with plural light spots of light emitted therefrom, a plurality of light detecting elelments to which reflected light of the light spots are guided, respectively, to adequately synthesize and compare outputs of said light detecting elements, thereby reading information recorded in tracks of the record medium, and detecting an tracking error and a focusing error, and a hologram element which splits light emitted from the light source into plural beams is disposed in an optical path between the light source and the record medium, said hologram element is split by a split line, said split line elongating in a direction perpendicular to a track of the medium on an optical axis, and a hologram pattern having a diffraction function which is substantially directed in the track direction is disposed on at least one side of said split line, thereby differentiating diffraction conditions on both sides of said split line from each other.
    Type: Grant
    Filed: September 5, 1995
    Date of Patent: June 2, 1998
    Assignee: Kabushiki Kaisha Sankyo Seiki Seisakusho
    Inventors: Tadashi Takeda, Yoshio Hayashi, Ikuo Kasuga, Kazuo Higashiura, Noriyuki Satoh, Hisahiro Ishihara
  • Patent number: 5739952
    Abstract: A polarizing beam splitter includes: an optically isotropic substrate; a layer of birefringent material formed on top of said optically isotropic substrate; and a periodic pattern of ridges and grooves formed on a surface of said optically isotropic substrate to make a grating; and a refractive index equal to either the refractive index of the birefringent material for ordinary light or the index for extraordinary light, said grooves being filled with the material.
    Type: Grant
    Filed: April 14, 1995
    Date of Patent: April 14, 1998
    Assignee: Kabushiki Kaisha Sankyo Seiki Seisakusho
    Inventors: Tadashi Takeda, Yoshio Hayashi, Hideo Takezoe, Ken Ishikawa
  • Patent number: 5715219
    Abstract: A displacement detecting device for optical head is disclosed which is capable of stably generating displacement detecting signals without being affected by fluctuation of wavelength of light emitted from a light source. The displacement detecting device is provided for use in an optical head which comprises a optical sensor for reading information recorded on an optical information recording medium by irradiating the optical information recording medium with light from a light source and detecting reflected light from the irradiated surface of the recording medium as well as detecting focus displacement and track displacement by utilizing diffracted light of the reflected light. The optical sensor is provided with wavelength fluctuation component detector for detecting wavelength fluctuation components in the reflected light.
    Type: Grant
    Filed: May 22, 1996
    Date of Patent: February 3, 1998
    Assignee: Nippon Steel Corporation
    Inventors: Tadashi Takeda, Kenji Fukui, Ricardo Musashi Okamoto, Hiroyuki Wada
  • Patent number: 5687152
    Abstract: A tracking error signal and a focus error signal can be obtained with those components of the light (plus and minus first-order light) which have been diffracted by a hologram device whereas the undiffracted zero-order light component is for the sole purpose of producing RF signals. As a result, RF signals can be detected without using a segmented photodetector while insuring that output signals of a constant intensity are produced even if there are changes in the spot diameter and position. In addition, any aberrations that are caused by an half-mirror are corrected by optics that is provided in the optical path connecting the half-mirror and the light-receiving elements of a photodetector and this insures that even if an objective lens moves, detection spots on the individual light-receiving elements will move on the latter without causing any offset errors.
    Type: Grant
    Filed: October 25, 1995
    Date of Patent: November 11, 1997
    Assignee: Kabushiki Kaisha Sankyo Seiki Seisakusho
    Inventors: Tadashi Takeda, Yoshio Hayashi
  • Patent number: 5648950
    Abstract: In an optical pickup system, the light emitted from a source to illuminate an optical recording medium is reflected and directed via a beam splitter to a photodetector so as to read information signals, and a hologram device for splitting the emerging light from the source into a plurality of beams is provided as an integral part of the entrance surface of the beam splitter.
    Type: Grant
    Filed: October 25, 1995
    Date of Patent: July 15, 1997
    Assignee: Kabushiki Kaisha Sankyo Seiki Seisakusho
    Inventors: Tadashi Takeda, Yoshio Hayashi
  • Patent number: 5351230
    Abstract: This invention pertains to a displacement detecting device for an optical head for detecting focal point displacement of irradiation light. The displacement detecting device has optical means for converting reflected rays from an irradiated face into an astigmatic bundle of rays and a photodetector for detecting a change in the the focused shape. The displacement detecting device thus detects focal point displacement of irradiation light. The optical means is obtained by integrally forming a plurality of Fresnel zone plates having rectilinear gratings, focusing reflected rays from the irradiated face, and having different focal lengths.
    Type: Grant
    Filed: October 22, 1992
    Date of Patent: September 27, 1994
    Assignee: Nippon Steel Corporation
    Inventors: Tadashi Takeda, Hiroyuki Wada, Kenji Fukui, Ricardo M. Okamoto, Shohei Hashiguchi