Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium
Reexamination Certificate
1999-03-24
2001-06-12
Edun, Muhammad (Department: 2651)
Dynamic information storage or retrieval
Specific detail of information handling portion of system
Radiation beam modification of or by storage medium
C369S047500, C369S053260
Reexamination Certificate
active
06246660
ABSTRACT:
This application claims the benefit of Japanese Patent Application No. 10-95415 filed on Mar. 24, 1998, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for controlling the recording power of an optical beam used to record information onto an optical recording medium and more particularly to a device for controlling the recording power in digital video disc (DVD) drives.
2. Description of the Related Art
Various optical recording media are known. One example is a write once read many (WORM) optical disk to which information can be written once using an organic dye material. Another example is a rewritable optical disk that can be rewritten repeatedly using a phase-changing material or a magneto-optical material. With these optical recording media, information is recorded by making use of the fact that a physical property of the recording surface is varied by thermal energy of an optical beam impinging on the recording surface.
In the case of these optical recording media, the recording power may not be optimal, depending on the recording medium, even if the same recording material is used in every commercial product, and if uniform optical beam power is established for the same material, because the characteristics of the material are different among the individual commercial products.
In this kind of information storage system for recording information on such an optical recording medium, optimum power control (OPC) is provided before information is started to be recorded. That is, the recording power of the optical beam is optimized for the optical recording medium.
The optimum power control (OPC) is provided in the manner described below. Usually, before recording is started, trial writing is done into a region formed in a given position of the recording medium, called a PCA (power calibration area), while varying the power value within a given range. The tentatively written testing information is reproduced. The power value producing a reproduced signal having the least jitter is established as the recording power best suited for the recording medium. In this way, the power can be optimized under these conditions.
Generally, the recording conditions vary slightly depending on the recording position even if the same optical recording medium is used. For example, fingerprints might be scattered on the recording surface of the optical recording medium or the medium may be warped, varying the shape. This makes the recording conditions at each recording position different from the recording conditions in the power calibration area (PCA) described above. Accordingly, if recording is made over the whole surface of the recording medium with the given optimum power found in the PCA, the recording power might be excessive or insufficient depending on the recording position.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above circumstances and has as an object the controlling or optimizing of a recording power of a recording optical beam by a control device at every recording position on an optical disk. This control is herein referred to as running OPC (optimum power control).
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
To achieve the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention comprises a recording power control device for use with an optical disk drive for recording information on an optical recording medium in a recording direction with a recording optical beam having a recording power. The optical disk drive emits an adjusting optical beam simultaneously with the recording optical beam behind the recording optical beam. The optical disk drive has a light-receiving component for receiving the adjusting optical beam reflected from the optical recording medium. The recording power control device acts to control the recording power of the recording optical beam. The recording power control device includes a recording power control component for controlling the recording power of the recording optical beam preceding the adjusting optical beam in the recording direction according to an output signal from said light-receiving component.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only are not restrictive of the invention, as claimed.
REFERENCES:
patent: 5699342 (1997-12-01), Yagi et al.
patent: 6115338 (2000-09-01), Masaki et al.
patent: 0 800 165 A1 (1997-10-01), None
patent: 9-326138 (1997-12-01), None
Edun Muhammad
Morgan & Lewis & Bockius, LLP
Pioneer Electronic Corporation
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