Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Patent
1998-04-22
2000-05-09
Huber, Paul W.
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
369 4429, 369 94, G11B 700
Patent
active
060613106
ABSTRACT:
The invention provides an apparatus for reproducing data recorded on a disk-shaped storage medium including a plurality of signal layers, the apparatus being capable of switching the location of an objective lens through which a light beam is projected onto the disk-shaped storage medium, from a location where the objective lens focuses the light beam onto a first signal layer to a location where the objective lens focuses the light beam onto a second signal layer, the apparatus comprising: movement control means for moving the objective lens by outputting a movement control signal having a predetermined level at a predetermined time so that the objective lens can reach a location within a range which allows the objective lens to be drawn to a just focusing position associated with the second signal layer; velocity detection means for detecting the velocity of the objective lens from the waveform of a focusing error signal at a predetermined time prior to a zero-crossing time at which the objective lens is located at the just focusing position associated with the second signal layer; and focus drawing means for closing a focusing servo loop at a time corresponding to the above-described velocity. With the apparatus according to the invention, it is possible to perform the focus jumping operation in a reliable fashion regardless of conditions such as the position in which a disk drive is placed, the sensitivity variation of a biaxial driver, and the variation in the distance between layers of the disk.
REFERENCES:
patent: 5263011 (1993-11-01), Maeda et al.
patent: 5740136 (1998-04-01), Tsutsui et al.
patent: 5793721 (1998-08-01), Akkermans
patent: 5999503 (1999-12-01), Tateishi et al.
Huber Paul W.
Sony Corporation
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