Optical disc player with focus control for preventing erroneous

Details Optical disc player with focus control for preventing erroneous Optical disc player with focus control for preventing erroneous

1987-03-05

1990-01-02

Psitos, Aristotelis M.

Dynamic information storage or retrieval

Control of storage or retrieval operation by a control...

Mechanism control by the control signal

250201AL, G11B 700

Patent

active

048917982

ABSTRACT:
An optical disc player in which prior to a focus servo control carried out by a focus control mechanism on the basis of an indication of a focus error signal, focusing control means causes an objective lens to approach to an optical disc so that a focused position of the beam light incident on the optical disc is brought on the signal recording surface or in the vicinity thereof, i.e., in a predetermined focusing range including a part of a high light reflectivity portion surrounding the signal recording surface. Consequently, the mode transfer to focus control operation by the focus control mechanism can be accurately carried out without an incorrect determination that the incident beam light on the optical disc has focused on an outer surface of the optical disc, i.e., of a transparent substrate or transparnt protection layer having light reflectivity substantially equal to that of the signal recording surface.

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