Static information storage and retrieval – Information masking – Transparency
Patent
1988-08-12
1991-03-19
Fears, Terrell W.
Static information storage and retrieval
Information masking
Transparency
365120, G11C 1304
Patent
active
050016679
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to means for data recording and reading and, more particularly, to optical memories or storage devices.
2. Description of the Related Art
Known in the art is an optical memory comprising a source of modulated electromagnetic radiation (gas laser), a photodetector, one working station for an optical disk data carrier as well as a library of the optical disk data carriers and a means for transferring thereof to, and from the working stations. The use of the optical disk data carrier makes it possible to provide a direct access to data and, hence, somewhat reduce the time for access to data (EP, B, 0106570).
A disadvantage of this solution resides in that the access time which comprises the time for transferring, inserting, accelerating, stopping and removing the optical disk data carrier remains too long. Another disadvantage resides in poor reliability of recording and reading since the working station is provided with only one optical head, the failure of which will make data recording and reading impossible.
Known in the art is an optical memory comprising the following optically coupled members: modulated electromagnetic radiation sources using laser diodes, photodetectors, and sixteen working stations for optical tape carriers placed in sealed cassettes each having an informational capacity of 6 Gbytes as well as a library of the tape data carriers and a means for transferring thereof to, and from, the working stations. (Mini-Macro Systems, June, 1984, Keith Jones "DOC data plans to make 6,000 M-byte optical-type cassette" pp. 98, 101).
In this memory, the time for access to data is from 1 to 10 s which results from a consecutive access to data on the tape carrier. Another disadvantage resides in poor reliability of recording and reading since each data carrier working station is provided with only one optical head, the failure of which will make recording and reading impossible.
SUMMARY OF THE INVENTION
The invention provides an optical memory which permits reduction in the time for access to data owing to a change in the order of, and simultaneous performance of, certain operations of the process of organizing the access to data being recorded or read.
This problem is solved by an optical memory in which movable optical data carriers are is placed at one or more of at least two stations by a means for transferring the optical carrier from its storage, the optical data carrier being optically coupled to at least one modulated electromagnetic radiation source and at least one photodetector. The optical storage device further comprises a switching unit for switching modulated electromagnetic radiation from the modulated electromagnetic radiation source to the optical data carriers and from the optical data carriers to the photodetector in accordance with the address of the station where a respective optical data carrier is disposed.
The switching unit of the modulated electromagnetic radiation may comprise a light beam splitter equally spaced from the optical data carriers when they are disposed at a respective station and a lens rotatable simultaneously with the light beam splitter and optically coupled thereto.
When the optical data carrier is made cylindrical, rotatable about its axis, the rotation axis of the light beam splitter is preferably disposed in parallel with the rotation axis of the optical cylindrical data carrier.
This embodiment of the optical memory improves reliability of recording and reading data and reduces the time for the access thereto.
BRIEF DESCRIPTION OF DRAWINGS
The invention will now be described with reference to specific embodiments shown in the accompanying drawings, in which:
FIG. 1 shows a block diagram of an optical memory, according to the invention:
FIG. 2 shows a block diagram of another optical memory, according to the invention;
FIG. 3 is a view of a switching unit, according to the invention;
FIG. 4 is a view showing the relative three-dimensional position of rotatable light beam s
REFERENCES:
patent: 2994863 (1961-08-01), Trapnell
patent: 3148355 (1964-09-01), Sliter
patent: 3215989 (1965-11-01), Ketchledge
patent: 3226697 (1965-12-01), Fujitsubo
patent: 4470137 (1984-09-01), Tago
patent: 4519061 (1985-05-01), Dahneke
"Mini-Micro Systems", Jun., 1984, Keith Jones.
"Doc Data Plans to Make 6,000 m-Bytes Optical Type Cassette", pp. 98, 101.
Antonov Alexandr A.
Petrov Vyacheslav V.
Fears Terrell W.
Institut Problem Modelirovania v Energetike Akademii Nauk
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