Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium
Patent
1987-10-06
1990-03-13
Sikes, William L.
Dynamic information storage or retrieval
Specific detail of information handling portion of system
Radiation beam modification of or by storage medium
369126, 369153, 3461531, 346 76L, 358300, G11B 700, G01D 1510, H04N 123
Patent
active
049088149
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to the field of information recording, reading and erasing, which are based on relative movement of an information carrier and a source of electromagnetic radiation, and, in particular, in concerned with methods of photothermal recording, reading and erasing of information.
BACKGROUND ART
The present invention deals with one of the vital problems of photothermal recording and storage of digital information, which is effected by means of optical storage devices capable of erasing information and recording it again. The existing methods of reversible recording of data, which make use of reversible magnetooptical and structural transformations in the recording media based on chalcogenide resins are extremely difficult to realize.
Known in the art is a method of photothermal information recording, reading and erasing, based on hydrodynamic effect in heated thin films of liquid (A. L. Kartuzhansky, Neserebrianye Protsessy Tonkikh Plenok Zhidkosti, 1984, Khimiya Publ., Leningrad, pp. 231-232), which consists in that changes in the geometry of the thinfilm surface, corresponding to information being recorded and dictated by the temperature relations of the surface energy in this film, are obtained by irradiating the film which absorbs this radiation.
This prior art method is deficient in that the storage period is too short and the sensitivity and resolution are too low, which is inherent in the liquid film characterized by thermal quasi-equlibrium of hydrodynamic relaxation.
Also known in the art is a method of photothermal information recording, reading and erasing (A.L. Kartuzhansky, Neserebrianye Fotograficheskie Protsessy, 1984, Khimiya Publ., Leningrad, pp. 44-49), comprising the steps of producing a potential pattern in the recording medium film by preliminary uniform charging of this film surface by a corona discharge, projecting an image to be recorded onto the film in the spectral range corresponding to the photoconductivity of the film material, developing the latent pattern by simultaneously softening the entire film by heating, and fixing the pattern, e.g. by cooling the film surface. The pattern recorded by this method is erased by heating and softening the recording medium.
The prior art method of photothermal information recording, reading and erasing can be used for multiple information rewriting. It is highly sensitive and offers a long period of storage. But this method is deficient in that the level of noise is too high because of the inherent deformations of photoplastic materials. Moreover, duration of one recording-erasing cycle is too long due to the contributing factors, such as the time required for charging the surface of the film, low mobility of current carriers in the photoplastic material, and the period of thermal relaxation of the recording medium. The resolution of the method is not high enough for the information recording and reading to be performed with a density provided by optical systems. In addition, the transmission band is too narrow. These deficiencies are inherent in the techniques of producing a latent pattern and developing this pattern over the entire surface of the thin film. To realize this prior art method, it is necessary, at first, to delineate a latent pattern which is a varying density of the surface charge throughout the film surface. Such variations in the surface charge density are dictated by the brightness of the pattern projected onto the film surface. This imaging technique is time-consuming and is the one of the sources of noises. The latent pattern is developed by simultaneous softening of the entire film and this brings out, as a surface relief pattern, not only the latent image but also interferences. In addition, heating and subsequent cooling of the entire recording medium requires too much time. To summarize, this prior art method cannot provide optimal conditions for film deformation during photothermal recording and erasing of an information unit. It cannot provide photothermal recording and erasing o
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Antonov Alexandr A.
Grinko Dmitry A.
Krjuchin Andrei A.
Petrov Vyacheslav V.
Healy Brain M.
Institut Problem Modelirovanija v Energetiki AN Ukr. SSR
Sikes William L.
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