Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Patent
1998-06-09
2000-09-19
Tran, Thang V.
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
369 54, 369 4432, G11B 390
Patent
active
061222372
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an optical disk apparatus for recording (writing) and/or reproducing (reading) information by using an optical disk, such as an optical disk, a magneto-optical disk or the like, as an information recording medium, and more particularly to an optical disk apparatus in which an attitude between the optical disk and the optical pickup is set to a predetermined initial state prior to performing an information recording or reproducing operation.
BACKGROUND ART
A general disk drive apparatus has employed as an information recording medium a CD (compact disk) only for playback, a CD-ROM (read-only memory) and so on in which a music data, an information data processed by a computer and so on are previously recorded. An optical disk such as a write-once type OD (magneto-optical disk) or the like on which data can be recorded again is also employed as the information recording medium.
A disk drive apparatus for storing and/or reproducing information by using these optical disks as an information recording medium has a disk table fitted to a rotation shaft of a spindle motor, an optical pickup device for writing and/or reading an information signal on and/or from an optical disk loaded onto the disk table. The optical disk is horizontally loaded onto the disk table and then rotated while a light beam is irradiated by an objective lens of an optical pickup device on an information recording surface of the optical disk. Then, while He objective lens is moved in parallel to the information recording surface, information is recorded on the information recording surface and information previously recorded thereon is reproduced.
When such disk drive apparatus is used to record and/or reproduce data on and/or from the optical disk with satisfactory recording and reproduction characteristics, the objected lens of the optical pickup device for reading the information on the information recording surface of the optical disk must be positioned and inclined at an angle within a predetermined range relative to the information recording surface of the optical disk. The reason for this is that inclination of the objective lens largely depends upon accuracy of reproduction of the information signal.
In this case, if the optical disk is recorded and/or reproduced with high density and high accuracy, then it is preferable to set an optical axis of the objective lens perpendicularly (90.degree.) to the optical disk. If the light beam is made incident on the information recording surface of the optical disk vertically, then a beam spot of the light beam irradiated on the information recording surface has a circular shape. As a result, it becomes possible for the beam spot to precisely scan one recording track formed on the information recording surface, and hence it is possible to record and/or reproduce data with satisfactory recording and reproduction characteristics.
However, inclination of the optical disk, a vertical-direction posture of a spindle motor, a vertical-direction posture of an objective lens and so are fluctuated, which makes it difficult to accurately set an optical axis of the objective lens perpendicularly to the optical disk. Therefore, in the disk drive apparatus employing an optical disk as an information recording medium, in consideration of inclination of an optical disk, accuracies in attachment of a spindle motor and an optical pickup device and so on, an allowance of a relative inclination of an information recording surface of the optical disk relative to an optical axis of an objective lens is determined in the standard.
An disk drive apparatus using an optical disk, such as a CD, a CD-ROM or the like, having a diameter of 12 cm is standardized to have an allowable range for the relative inclination angle between the optical disk and the objective lens which is determined to be 1.2.degree. or less (the inclination of the optical disk is standardized to be 0.6.degree. or less and the inclination of each of the spindle motor and the objective lens of the di
REFERENCES:
patent: 5657303 (1997-08-01), Namoto et al.
Ohmori Kiyoshi
Seto Hidekazu
Sony Corporation
Tran Thang V.
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