# US 7,613,082 B2 · Optical pickup device, optical recording and reproducing apparatus and gap detection method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,613,082 B2 - Document ID: US7613082B2 - Status: Granted - Kind: B2 - Application number: 11/118,559 - Filed: 2005-05-02 - Published: 2005-11-24 - Granted: 2009-11-03 - Earliest claimed: 2004-05-18 - Assignees: Sony Corporation - Inventors: Tsutomu Ishimoto; Kimihiro Saito - Web page: https://patentgrep.com/patent/US7613082B2 ## CPC - G11B 7/0908: {for focusing only (G11B7/0925, G11B7/094, G11B7/0941, G11B7/0943, G11B7/0945, G11B7/0946, G11B7/0948 take precedence)} - G11B 7/0956: {to compensate for tilt, skew, warp or inclination of the disc, i.e. maintain the optical axis at right angles to the disc} - G11B 7/1353: Diffractive elements, e.g. holograms or gratings {(diffraction gratings per se G02B5/18; holograms per se G02B5/32; grating systems G02B27/44)} - G11B 7/1387: using the near-field effect - G11B 2007/13727: {Compound lenses, i.e. two or more lenses co-operating to perform a function, e.g. compound objective lens including a solid immersion lens, positive and negative lenses either bonded together or with adjustable spacing} - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) ## Abstract An optical pickup device comprising at least a light source, an optical unit for irradiating an optical recording medium with a plurality of lights from this light source, a head unit located in an opposing relation to the optical recording medium and converging a plurality of lights emitted from the light source on a recording surface of the optical recording medium as near field light, a photo-detecting unit for detecting an angle between the head unit and the recording surface of the optical recording medium based on quantities of returned lights from the optical recording medium and a tilt control unit for controlling the tilt driving unit based on an angle detected by the photo-detecting unit so that an angle of the head unit relative to the recording surface is held constant. Then, an optical pickup device, an optical recording and reproducing apparatus and a tilt detection method are able to automatically control a tilt without requiring setting up an external sensor independently of an optical pickup. ## Claims ### Claim 1 An optical pickup device comprising: a light source configured to generate a plurality of light beams, said plurality of light beams including a first light beam and a second light beam; a head unit located in an opposing relation to an optical recording medium and configured to irradiate said plurality of light beams emitted from said light source on said optical recording medium as near field lights so as to form a plurality of light beam spots on said optical recording medium; and a photo-detecting unit configured to detect a plurality of quantities of returned light respectively of said plurality of light beams returned from said head unit so as to detect a gap between said head unit and a recording surface of said optical recording medium based on at least one of said plurality of quantities of returned light, and so as to detect a tilt angle of said head unit relative to said recording surface of said optical recording medium based on a difference between two quantities of returned light from among said plurality of quantities of returned light, said two quantities of returned light being quantities of returned light respectively of said first light beam and said second light beam that are returned from said head unit, wherein said head unit includes a first lens and a second lens located between said first lens and said optical recording medium, and wherein said second lens is configured to generate near field light. ### Claim 2 (depends on 1) An optical pickup device according to claim 1, wherein said light source is configured to generate said plurality of light beams by splitting light from a laser diode. ### Claim 3 (depends on 1) An optical pickup device according to claim 1, wherein said light source includes a plurality of laser diodes such that said plurality of light beams are generated by said plurality of laser diodes. ### Claim 4 (depends on 1) An optical pickup device according to claim 1, wherein said second lens is a solid immersion lens. ### Claim 5 (depends on 1) An optical pickup device according to claim 1, wherein said photo-detecting unit detects a gap between said head unit and a recording surface of said optical recording medium based on a quantity of returned light reflected on said second lens at its end face opposing said optical recording medium. ### Claim 6 (depends on 1) An optical pickup device according to claim 1, further comprising: a gap driving unit configured to adjust a distance between said head unit and said recording surface of said optical recording medium; and a gap control unit configured to control said gap driving unit based on said distance detected by said photo-detecting unit so that a distance of said head unit relative to said recording surface is held constant. ### Claim 7 (depends on 1) An optical pickup device according to claim 1, wherein when a distance between said head unit and said recording surface of said optical recording medium is detected based on more than one of said plurality of quantities of returned light, said distance is detected based on a mean value of quantities of said more than one of said plurality of quantities of returned light, or said distance is detected based on a quantity of returned light at a central position if said plurality of light beams form an odd number of beam spots on said optical recording medium, or said distance is detected based on a mean value of quantities of two returned light beams at the central position if said plurality of light beams form an even number of beam spots on said optical recording medium. ### Claim 8 (depends on 1) An optical pickup device according to claim 1, further comprising: a tilt driving unit configured to adjust an angle between said head unit and said recording surface of said optical recording medium; and a tilt control unit configured to control said tilt driving unit based on said tilt angle detected by said photo-detecting unit so that an angle of said head unit relative to said recording surface is held constant. ### Claim 9 An optical pickup device comprising: a light source configured to generate a plurality of light beams, said plurality of light beams including a first light beam and a second light beam; a head unit including first and second lenses, said second lens being located in an opposing relation to an optical recording medium and being configured to converge said plurality of light beams emitted from said light source to generate near field light toward said optical recording medium; and a photo-detecting unit configured to detect a plurality of quantities of returned light respectively of said plurality of light beams returned from said head unit so as to detect a tilt angle of said head unit relative to a recording surface of said optical recording medium based on a difference between two quantities of returned light from among said plurality of quantities of returned light, said two quantities of returned light being quantities of returned light respectively of said first light beam and said second light beam that are returned from said head unit, wherein said head unit generates near field light by said second lens at its end face opposing said optical recording medium and reflects said plurality of light beams introduced from said light source at said end face. ### Claim 10 (depends on 9) An optical pickup device according to claim 9, wherein said light source is configured to generate said plurality of light beams by splitting light from a laser diode. ### Claim 11 (depends on 9) An optical pickup device according to claim 9, wherein said light source includes a plurality of laser diodes such that said plurality of light beams are generated by said plurality of laser diodes. ### Claim 12 (depends on 9) An optical pickup device according to claim 9, wherein said photo-detecting unit is configured to detect a gap between said head unit and said recording surface of said optical recording medium based on at least one of said plurality of quantities of returned light reflected by said second lens at its end face opposing said optical recording medium. ### Claim 13 (depends on 12) An optical pickup device according to claim 12, wherein when a distance between said head unit and said recording surface of said optical recording medium is detected based on more than one of said plurality of quantities of returned lights, said distance is detected based on a mean value of quantities of said more than one of said plurality of quantities of returned light, or said distance is detected based on a quantity of returned light at a central position if said plurality of light beams form an odd number of beam spots on said optical recording medium, or said distance is detected based on a mean value of quantities of two returned light beams at the central position if said plurality of light beams form an even number of beam spots on said optical recording medium. ### Claim 14 (depends on 9) An optical pickup device according to claim 9, further comprising: a gap driving unit configured to adjust a distance between said head unit and said recording surface of said optical recording medium; and a gap control unit configured to control said gap driving unit based on said distance detected by said photo-detecting unit so that a distance of said head unit relative to said recording surface is held constant. ### Claim 15 (depends on 9) An optical pickup device according to claim 9, further comprising: a tilt driving unit configured to adjust an angle between said head unit and said recording surface of said optical recording medium; and a tilt control unit configured to control said tilt driving unit based on said tilt angle detected by said photo-detecting unit so that an angle of said head unit relative to recording surface is held constant. ### Claim 16 An optical recording and reproducing apparatus for recording and/or reproducing an optical recording medium by irradiating said optical recording medium with light from a light source, comprising: a light source configured to generate a plurality of light beams, said plurality of light beams including a first light beam and a second light beam; a head unit located in an opposing relation to said optical recording medium and configured to irradiate said plurality of light beams emitted from said light source on said optical recording medium as near field light so as to form a plurality of light beam spots on said optical recording medium; and a photo-detecting unit configured to detect a plurality of quantities of returned light respectively of said plurality of light beams returned from said head unit so as to detect a gap between said head unit and a recording surface of said optical recording medium based on at least one of said plurality of quantities of returned light, and so as to detect a tilt angle of said head unit relative to said recording surface of said optical recording medium based on a difference between two quantities of returned light from among said plurality of quantities of returned light, said two quantities of returned light being quantities of returned light respectively of said first light beam and said second light beam that are returned from said head unit, wherein said head unit includes a first lens and a second lens located between said first lens and said optical recording medium, and wherein said second lens is configured to generate near field light. ### Claim 17 (depends on 16) An optical recording and reproducing apparatus according to claim 16, further comprising: a gap driving unit configured to adjust a gap between said head unit and said recording surface of said optical recording medium; and a gap control unit configured to control said gap driving unit based on said gap detected by said photo-detecting unit so that a distance of said head unit relative to said recording surface is held constant. ### Claim 18 (depends on 16) An optical recording and reproducing apparatus according to claim 16, further comprising: a tilt driving unit configured to adjust an angle between said head unit and said recording surface of said optical recording medium; and a tilt control unit configured to control said tilt driving unit based on said tilt angle detected by said photo-detecting unit so that an angle of said head unit relative to said recording surface is held constant. ### Claim 19 A detection method comprising the steps of: emitting a plurality of light beams from a light source to a head unit, said plurality of light beams including a first light beam and a second light beam; irradiating the plurality of light beams on an optical recording medium though said head unit so as to generate a plurality of near field lights; detecting a plurality of quantities of returned light respectively of said plurality of light beams returned from said head unit; and detecting a tilt angle between a recording surface of said optical recording medium and said head unit based on a difference between two quantities of returned light from among said plurality of quantities of returned light, said two quantities of returned light being quantities of returned light respectively of said first light beam and said second light beam that are returned from said head unit.