Optical data retrieval system for multi-characteristic reflective data storage media

Patent 4642803 Issued on February 10, 1987. Estimated Expiration Date:

March 4, 2005. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

3305633

3624286

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Inventor

Drexler, Jerome

Application

No. 06/707538 filed on 03/04/1985

US Classes:

369/53.13, Due to unwanted operational condition of record carrier250/208.5, With photodetector output ratioing other than by bridge or push-pull circuits250/559.11, Detection of both reflected and transmitted light365/200, Bad bit369/101, Invisible radiation (e.g., electron beam or X-ray)369/111Spiral or helical track

Examiners

Primary: Faber, Alan

International Classes

G11B 7/12 (20060101)
G11B 27/36 (20060101)
G11B 7/08 (20060101)
G11B 7/013 (20060101)
G11B 7/24 (20060101)
G11B 7/0033 (20060101)
G11B 7/00 (20060101)

Abstract

A system for recovering data, both prerecorded and user data, from a reflective optical data storage medium, with the further capability of distinguishing data from foreign particulate matter on the data disk. A pair of detectors measures the fraction of light reflected from and transmitted through the data disk and, knowing the fraction of light absorbed by the disk, distinguishes user data from prerecorded data and particulate matter. The data disk has different optical characteristics for prerecorded and user data, the prerecorded information being black, highly absorptive silver, while the user data consists of pits of relatively high transmissivity in a reflective field. Particulate matter is recognized by intermediate reflectivity and transmissivity. The optical characteristics of the material are enhanced or exaggerated so that the two types of data and particulate matter can be distinguished.