Optical disk pickup device with focusing correction by electrostriction
Patent 5513158 Issued on April 30, 1996. Estimated Expiration Date: 
April 24, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
April 24, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesOptical data reader Device for processing optical data with improved optical allignment means Sensor array for focus detection Variable focus optical system and method using electro-optic material Intergrated optical head with flexible substrate portion Optical information reading apparatus with tracking adjustment system Patent #: 5027336 InventorAssigneeApplicationNo. 427159 filed on 04/24/1995US Classes:369/44.23, Structure for shaping beam or causing astigmatic condition250/201.5, With optical storage medium; e.g., optical disc, etc.369/112.02Crystal (e.g., liquid, elasto-optic, photo-refractive, etc.)ExaminersPrimary: Psitos, Aristotelis M.Assistant: Wilkinson, Duncan Attorney, Agent or FirmForeign Patent References
International ClassG11B 007/135Foreign Application Priority Data1991-11-20 JPAbstractAn optical pickup is adapted for recording and/or reproducing signals by radiating a light beam from a light source on an optical recording medium via an object lens. The optical pickup includes a light receiving device for receiving a return light from the optical recording medium, and a focusing error detecting unit for detecting an amount of deviation of the focal point along the optical axis. The measurement of a focusing error is based on signals from the light receiving device. The optical pickup further includes an electrostriction device arranged on a path of light outgoing from the light source to the optical recording medium and having a central section and a peripheral section exhibiting a phase difference from each other depending on an applied voltage.Focusing errors may be detected with high accuracy with the optical pickup. A focusing servo device compensates for the focusing error detected by controlling the focal point along the optical axis using a focusing servo device. Depending on error detection signals from the focusing error detection unit, a rough servo is carried out by an the object lens driving unit to the vicinity of the depth of focus, and a fine servo is carried out by the electrostriction device within the range of the depth of focus.Other References
Field of SearchSolid state optical element with plural dissimilar optical components (e.g., using I.C. block, etc.)Structure for shaping beam or causing astigmatic condition With optical storage medium; e.g., optical disc, etc. Active autofocus Of a microscope Automatic focus control With specific relative positional geometry of photosensitive elements (e.g., an annular photosensitive element surrounding a coaxially mounted photosensitive element) Hoods, grating, baffles, diaphragms, masks | |
