Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Patent
1994-12-13
1995-12-26
Young, W. R.
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
369 4437, 369 4441, 369 58, 369110, 369112, 369120, G11B 7095
Patent
active
054793874
ABSTRACT:
An optical recording/reproducing head device which includes a diffraction grating for splitting a light beam radiated from a light source into at least three light beams, an objective lens for converging the three light beams on a signal recording surface of a disc-shaped optical recording medium, driving means for driving the objective lens along a direction parallel to its optical axis and within a plane perpendicular to the optical axis, a beam splitter for splitting the light beam incident via the objective lens, a first photodetector having a light-receiving surface divided by two boundary lines into four sections, second and third photodetectors arrayed in a direction parallel to one of the boundary lines on both sides of the first photodetector and fourth and fifth photodetectors arrayed in a direction perpendicular to the one of the boundary lines on both sides of the first photodetector, a splitting optical element arranged between the photodetectors and the beam splitter for splitting each of the three light beams from the diffraction grating into three more light beams, and a focusing error detection optical element arranged between the photodetectors and the beam splitter, the focusing detection optical element causing changes in the shape of a spot on the light receiving surface of the first photodetector in accordance with displacement of the disc-shaped optical recording medium in a direction perpendicular to the in-plane direction of the disc-shaped optical recording medium.
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Ando Nobuhiko
Ando Ryo
Fujiie Kazuhiko
Shaw, Jr. Philip M.
Sony Corporation
Young W. R.
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