Stock material or miscellaneous articles – Circular sheet or circular blank
Reexamination Certificate
2000-01-24
2001-10-30
Evans, Elizabeth (Department: 1774)
Stock material or miscellaneous articles
Circular sheet or circular blank
C428S064400, C428S064800, C428S457000, C428S690000, C428S913000, C430S270120, C430S495100, C430S945000, C369S283000, C369S288000
Reexamination Certificate
active
06309729
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to methods for manufacturing optical memory devices such as compact discs (CD), tapes, cards, wires, cylindrical drums, or the like, the information from which is read out by optical means.
BACKGROUND OF THE INVENTION
Compact discs are known optical memory devices which are widely used particularly with playback and computer devices for retrieving musical and software compositions. Such devices typically comprise only one information carrying layer and, therefore, suffer from a limited amount of recorded data.
Three-dimensional optical memory devices have been developed typically comprising a plurality of parallel, spaced-apart layers having information carrying regions in which optical properties differ from those of adjacent regions of the layers. One example of such a device is disclosed in U.S. Pat. No. 4,090,031. The device comprises a substrate and a plurality of data layers provided on one side of the substrate. Each of the layers comprises data tracks formed of lines of data spots. The data spots are, in turn, formed of either binary coded digital information or frequency or pulse length modulated analog information which is photographically recorded. The data spots are light reflective. Selection of one data track for playback is accomplished by changing the focus of a reading light beam from one data layer to another, or by making the data tracks of materials having different optical properties, the reading light being of different wavelengths for different layers. To this end, different color dyes or different photoluminescent materials are used and corresponding color filters are selectively positioned in front of light detectors.
The device is manufactured in the following manner. The data layers are made of photosensitive, reflective material such as photographic film or another suitable recording material including printing ink. The data spots are formed of light reflecting metal material having a reflecting index different from that of the data layers. The data spots are fabricated by either vapor deposition through a mask having an aperture corresponding to the data spots, or etching through a photoresist mask.
It is thus evident that such a device suffers from multiple over-reflection when retrieving the information from the layers. Indeed, a reading beam would pass through all the layers, wherein each layer is reflective. This results in the number of layers being limited to two or three layers only. Additionally, such a technology based on the use of a photomask does not provide high information density, and is, therefore, not effective. It is appreciated that a process of manufacturing of such a device is very complicated and time-consuming. It is also understood that an extremely expensive technique is required for the production of each layer and, thereby, the entire process is very expensive. Therefore, such process is not suitable for mass production.
SUMMARY OF THE INVENTION
It is a major object of the present invention to provide a novel method of manufacturing an optical memory device, particularly such a method which is suitable for mass production of the optical memory devices.
It is a further object of the present invention to provide such a method which enables to manufacture a multi-layered optical memory device.
It is a still further object of the present invention to provide such a method which is suitable for manufacturing a recordable optical memory device.
There is thus provided according to one aspect of the present invention a method of manufacturing an optical memory device having a data layer formed on a substrate, the method comprising the steps of:
(a) forming an upper surface of the substrate with a pattern having a plurality of regions which are capable of obtaining, when covered by a recording medium, desired optical properties different from those of the substrate;
(b) coating the patterned surface of the substrate with the recording medium; and
(c) removing the recording medium from the patterned surface after the recording regions have obtained the desired optical properties.
In the step (a), the pattern may be in the form of a surface relief on the upper surface of the substrate. This may be achieved by forming the upper surface of the substrate with a plurality of recesses, for example, by means of a stamper device. Alternatively, the substrate itself may be in the form of a stamper substrate, in which case the method may also comprise, subsequently to the step (c), the step of placing an optical film onto the stamper substrate so that the recording medium filled in the recesses of the stamper substrate is stuck to the film in the regions corresponding to the recording regions on the stamper substrate. Each of the recesses has a sufficient depth to be at least partially filled with the recording medium.
The step of forming the pattern may comprise the step of forming the upper surface of the substrate with regions having adsorbing properties for adhering the recording medium thereto. This may be achieved by either processing the substrate at respective regions, or coating respective regions with an adsorbing material capable of holding thereon the recording medium.
The substrate is made of a transparent material. The recording medium may be made of a fluorescent or scattering material. The recording medium may be multi-layered and made, for example, of a reflective material coated by a fluorescent material.
According to another aspect of the present invention there is provided a method of manufacturing a three-dimensional optical memory device formed of a plurality of spaced-apart data layers each formed on a substrate, the method comprising the steps of:
(i) forming an upper surface of each of the substrates with a pattern comprising a plurality of regions which are capable of obtaining, when covered by a recording medium, desired optical properties different from those of the substrate;
(ii) coating the patterned surface of the substrate with the recording medium;
(iii) removing the recording medium from the patterned surface after the recording regions have obtained the desired optical properties; and
(iv) providing an attachment between the data layers.
According to yet another aspect of the invention, there is provided an optical memory device comprising a transparent data layer having an upper surface thereof patterned with a plurality of spaced-apart recording regions formed of a material having optical properties different from those of the transparent layer.
According to yet another aspect of the invention, there is provided a multi-layered optical memory device comprising a plurality of spaced-apart transparent layers, each layer having an upper surface thereof patterned with a plurality of spaced-apart recording regions formed of a material having optical properties different from that of the transparent layer.
More specifically the present invention is used for manufacturing multi-layered compact discs and is, therefore, described below with respect to this application.
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Glushko Boris
Levich Eugene
Birch & Stewart Kolasch & Birch, LLP
Evans Elizabeth
TriDStore IP, L.L.C.
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