Optical disk apparatus

Details Optical disk apparatus Optical disk apparatus

1989-10-24

1993-01-05

Psitos, Aristotelis

Dynamic information storage or retrieval

Information location or remote operator actuated control

Selective addressing of storage medium

369 4425, 369 4428, G11B 7085

Patent

active

051777185

ABSTRACT:
An optical disk apparatus comprising a head having an objective lens, a tracking controller, a CPU, and a counter. The CPU determines a tracking error if the count of the counter is greater than a predetermined value when the disk is rotated 360.degree. after the counter has been cleared during data-reproducing operation. Then, the CPU outputs a tracking re-try signal to the tracking controller. In response to this signal, the controller locks the lens at the center position within the head. Then, the frequency of vibration of the lens decreases so much that servo tracking is no longer required. When the relative rate-of-change of tracking position between the head and the disk has decreased sufficiently, the CPU determines that the head is applying a laser beam onto the target track of the disk. Thus, every time a tracking error is made due to an external force, the servo tracking is automatically performed, and the apparatus is therefore reliable. The CPU also outputs a tracking re-try signal if the head is stopped upon completion of coarse accessing of an optical disk. In this case, the lens is locked at the center position. Therefore, the vibration of the lens can be suppressed within a short time after the completion of the coarse accessing. As soon as the relative rate-of-change of tracking position between the lens and the disk decreases sufficiently, the head starts applying a laser beam onto the target track of the disk, thus tracking the optical disk.

REFERENCES:
patent: 4037252 (1977-07-01), Janssen
patent: 4684797 (1987-08-01), Ando et al.
patent: 4694443 (1987-09-01), Ando
patent: 4701897 (1987-10-01), Nakagawa
patent: 4764911 (1988-08-01), Mokota et al.
patent: 4887253 (1989-12-01), Tateishi
patent: 4918676 (1990-04-01), Miyasaka
patent: 4942563 (1990-07-01), Yamamuro

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