DE3229573A1 - OPTICAL RECORDING MATERIAL, INFORMATION CARRIER AND METHOD FOR PRODUCING AN OPTICAL RECORDING MATERIAL - Google Patents

Description

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The invention relates to an optical recording material having a substrate and a light-reflecting layer a flat surface of the substrate and a photosensitive layer on the light reflective layer. It also relates to an information carrier with the substrate, the light-reflecting and the light-sensitive Layer with the latter provided information track and relates to a method for producing an optical Recording medium.

In US-PS 40 97 895 a double-layer optical recording material is used with a light-reflecting layer covered with a light-absorbing layer. A corresponding three-layer optical recording medium with a transparent spacer layer between the reflective and the absorbent layer according to the aforementioned Patent is given in US Pat. No. 4,216,501. In any case, the information is provided by local Changing the optical properties of the material saved, e.g. by melting, peeling off or other changes in the optical properties of the absorbent layer. The resulting change in the transmittance or reflectivity of the recording material in the exposed areas is detected when reading out the recorded information.

Before exposure, these recording materials are related to their structural and. optical properties substantially uniform. Before storing the information, the known recording materials contain hence no means of limiting or following a trail. Such means would be in advance in the case of recording media produced groove in the substrate surface is present, in this case, however, there was no flexibility whatsoever for changes in the arrangement or identification of the track

after manufacturing. The flexibility would be with a further alternative in which a part of the light absorbing Layer removed with the aid of a laser beam to form protective strips between the light-absorbing tracks becomes, present, but the traces can by making the protection tape will be damaged and the protection tape cannot be recorded at a later time.

The invention is based on the object of a recording material to create with the protective strips in which the light-absorbing traces are undisturbed and in which the the respective information is also to be saved at a later point in time. The solution according to the invention is for the The optical recording material in claim 1, the information carrier comprising a recording material in claim 1 2 and described in claim 8 for the method for producing an optical recording material. Improvements and further developments of the invention are given in the subclaims.

Accordingly, the invention relates to an improved optical recording material, its photosensitive layer includes a track layer having at least one opening therethrough and one extending into the openings Absorption layer is covered so that first and second zones with different thicknesses arise, such that the reflectivity in the first zone is smaller than in the second zone. The information carrier according to the invention contains an optical recording material with information stored in the first zone.

According to the method according to the invention, one after the other a reflective layer and a track layer are applied to a substrate, then one or more openings Openings are created in the track layer and finally an absorption layer on the track layer and into the openings dejected.

Details of the invention are explained on the basis of the schematic representation of exemplary embodiments. Show it:

Fig. 1 is a perspective view, partly in section, of a double layer optical recording medium;

Fig. 2 is a cross section of a three-layer optical recording medium; and

Fig. 3. ·

and 4 cross sections of two information carriers.

The optical recording material denoted as a whole by 10 in FIG consists of a substrate 12, a backing layer 14 on a flat surface of the substrate 12, a light-reflecting layer 16 on the surface of the backing layer 14, a light-sensitive Layer 18 on the surface of the light reflective Layer 16 and a light absorbing layer 24 on the light reflecting layer 16. The light reflecting Layer 16 consists of a track layer 20 with one or more through openings 22. The light-reflecting Layer 16 covering light-absorbing layer 24 therefore extends into the openings 22 so that Recording tracks 26 and protective strips 28 arise or alternate.

2-4, the usual elements of the optical recording material 30 and the information carrier 40 and 50 as indicated in FIG. 1.

The optical recording material 30 of FIG. 2 contains, in addition to the elements of FIG. 1, a spacer layer 32 between the reflective layer 16 and the photosensitive Layer 18. In addition, a barrier layer 34 lies on top of the absorption layer 24 and one on top of it Top layer 36.

FIGS. 3 and 4 show information carriers 40 and 50 which are optical recording materials 10 of FIGS. 1 and 30, respectively of Fig. 2 with information recorded therein. The latter consists of one or more memory areas 42 of the absorbing layer 24 in the recording tracks 26. The storage areas 42 have optical properties, which differ from the optical properties of the remainder of the absorbent layer 24. The difference the optical properties of the storage areas 42 in FIG photosensitive layer 18 can result from an irreversible deformation of the absorption layer 24, e.g. Dimples or bubbles in the layer, or from a reversible change in the optical constants of the absorption layer 24, for example as a result of a change in the Degree of crystallinity of the absorbent layer, as described in German Offenlegungsschrift 31 18 058 will. The presence or absence of a change in the optical properties of the photosensitive Layer 18 leads to a change in the reflectivity of the recording material, whereby the length of the storage areas 42 and their mutual distance indicate the recorded information.

The protective strips 28 can also contain information e.g., track identification numbers, can be stored in the recording track 26 before or after information is recorded. Such information may consist of one or more areas 44 of the protective strip 28 which are defined by the optical properties of the rest of the protective strip have different optical properties.

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The substrate 12 can consist of glass, a plastic such as polyvinyl chloride or (poly) methyl methacrylate, or a metal such as aluminum. The backing layer 14 is a non-conforming cover layer made of a plastic, for example made of epoxy or acrylic resin, with a microscopically flat surface. The backing layer 14 may be deposited on the surface of the substrate 12 prior to the application of the reflective layer 16. The reflective layer 16 reflects a substantial proportion, preferably at least 50 %, of the incident light of the wavelength of a storage light beam and can consist of a metal, for example aluminum or gold, or be produced as a dielectric multilayer reflector.

The spacer layer 32 of the recording material 30 is substantially at the recording and readout wavelengths transparent and non-scattering.

Suitable materials for making this layer are organic substances such as fluorocarbons and hydrocarbons material polymers, and inorganic materials, such as Oxidje, from. Silicon, titanium, magnesium and aluminum. These materials can be applied to the reflective layer in the usual way 16 be knocked down. The track layer 20 absorbs light of the wave used to make the openings length and can consist of organic or inorganic material. Suitable inorganic materials are bismuth, Titanium, rhodium, tellurium, selenium and tellurium or selenium-containing chalcogenide compounds. The track layer 20 can be between about 20 and 160 nanometers thick. The layer thickness is preferably chosen so that the reflectivity of the combination of reflective layer and track layer at the wavelength used to form the openings 22 is reduced. The openings 22 can have the shape of a continuous or discontinuous circular or spiral groove.

The absorbing layer 24 is made of one in the recording light beam sensitive organic or inorganic material. Suitable inorganic materials are bismuth, rhodium, titanium, tellurium, selenium and tellurium and selenium-containing chalcogenide compounds. the The thickness of the absorbent layer 24 in the recording tracks 26 is chosen so that the reflectivity of the optical recording materials within the recording tracks 26 are reduced and preferably correspondingly the anti-reflection condition is minimized. For the optical Recording material 10 can determine the optimum layer thickness from the optical constants of the reflective layer 16, the absorbent layer 24 and each overlying it Layer can be determined by known methods for a specific wavelength. In typical cases, the Layer thickness between about 20 and 100 nanometers. The sum of the layer thicknesses of the track layer 20 and the absorbent Layer 24 in the area of the protective strips 28 is chosen so that that the reflectivity of the particular wavelength is greater than that in the recording tracks 26.

In the case of the optical recording material 30, the layer thickness can of the absorption layer 24 from the layer thicknesses of the spacer layer 32 and the optical constants of the reflective Layer 16, spacer layer 32, absorbent layer 24 and any overlying layer will. In typical cases, the layer thickness of the absorption layer 24 is 3 to 100 nanometers.

The barrier layer 34 is made of a light transmissive material which is thermal and chemical The barrier between the absorbent layer 24 and the cover layer 36 represents. The barrier layer 34 is preferred composed of an oxide of aluminum, magnesium, silicon

silicon or titanium and should have a layer thickness between about 50 and 500 nanometers. The cover layer 36 is preferably made of a light transmissive material such as silicone rubber formed with a layer thickness of about 500 to 1500 micrometers. Such a combination of blocking and cover layers are described in US Pat. No. 4,101,907.

According to the above, the invention relates to a recording material, its light-sensitive layer of thicker and thinner zones with the difference in thickness accordingly different reflectivities. The exemplary embodiment described relates to the case in which the thickness of the absorbing layer in the recording tracks is chosen so that the reflectivity of the Recording tracks compared to that of the protective strips is reduced. However, the reverse arrangement can also be used with exchanged rolls of recording tracks and protective strips. The optical constant and the layer thickness of the entirety of the track and absorption layers is then chosen so that the reflectivity is lower in the area of the protective strips than in the area of the recording tracks. However, the first alternative will preferred because here the information to be recorded by melting, peeling or in some other way to be changed Amount of material in the area of the recording tracks is minimal. Also, the information is recorded in a layer that is not disturbed after it is deposited while making the groove may cause disturbance of the track layer.

When operating an optical recording, reading out or in an erasure system, the recording, reading out or erasing light beam centered on a track. As the reflectivity of the two zones of the optical recording materials or the recording medium differs, the radial offset of the recording beam or a

Scanning beam as a change in the reflecting beam intensity be registered. This change can be proportional to the offset of the light beam relative to the track electrical signal can be converted. The electrical signal obtained in this way can in turn be used for the Correct the position of the recording, reading or deleting light beam.

For the method according to the invention for producing the optical Recording material includes the following steps: depositing a backing layer onto the surface of a Substrate; Depositing a light reflective layer on the surface of the backing layer; Knock down a track layer of absorbent material on the light reflective layer; Form one or more openings through the track layer; Depositing an absorbent layer on the track layer and in the openings in; and depositing barrier and cover layers on the absorbent layer. The openings can be formed by peeling off or melting and peeling off the molten material with the aid of a laser beam will. The wavelength of the laser beam should match or differ from that for later recording the wavelength used for the information. The openings can alternatively also be photolithographic or chemical Etching can be produced in a known manner.

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Claims (1)

Dr.-lng. Reirnan König .. '■ ^: · Dipl.-Tnjg.:Khaus Bergen Cacilienallee 76 4 Düsseldorf 3O Teleion 452DQB Patent Attorneys August 6, 1982 34 569 B RCA Corporation, 30 Rockefeller Plaza,
New York, NY 10020 '(V.St.A.) "Optical recording material, information carrier and Method of making an optical recording materials " Patent claims: Optical recording material (10) with a substrate (12), a light-reflecting layer (16) on a flat surface of the substrate (12) and a light-sensitive layer (18) on the light-reflecting layer (16), characterized by a track layer (20) on the light-reflecting layer (16) with one or more through openings (22), a light-absorbing layer (24) on the track layer (20) and on the light-reflecting layer (16) within the openings (22) of the track layer (20), such that within the light-sensitive layer (18) two zones (26, 28) are formed, of which the reflectivity of the first zone (26) is smaller than that of the second zone (28) at a certain wavelength. 2. Information carrier (40, 50) with a substrate (12), a light-reflecting layer (16) on a plane Surface of the substrate (12) and a light-sensitive layer (18) with information provided therein 3229579 mation track on the light-reflecting layer (16), characterized by a track layer (20) on the light-reflecting layer (16) with one or more through openings (22), a light-absorbing layer (24) on the track layer (20) and on the light-reflecting layer (16) within the openings (22) of the track layer (20), such that two zones (26, 28) are formed within the light-sensitive layer (18), of which the reflectivity of the first zone (26) at a certain wavelength is less than that of the second zone (28), the information track consisting of one or more areas (42) of the first zone (26) which have optical properties that differ from the rest of the first zone. 3. Material according to claim 1, characterized in that a spacer layer (32) is inserted between the light-reflecting layer (16) and the track layer (20). 4. Carrier according to claim 2, characterized in that a spacer layer (32) is inserted between the light-reflecting layer (16) and the track layer (20). 5. The article according to one or more of claims 1 to 4, characterized in that the spacer layer (32) is formed from an oxide of silicon, magnesium, aluminum or titanium. 6. Object according to one or more of claims 1 to 5, characterized in that the track and absorption layers (20) consist of bismuth, titanium, rhodium, tellurium, selenium or chalcogenide compounds with tellurium or selenium. 7. The article according to one or more of claims 1 to 6, characterized in that the second zone contains an information track and that the information track consists of two or more areas of the second zone with different optical properties of the material of the zone than the rest of the second zone . 8. A method for producing an optical recording material, characterized in that a light-reflecting layer (16) on the surface of a substrate (12) and a track layer (20) on the light-reflecting layer (16) is deposited that one or more through openings in of the track layer (20) and that a light absorbing layer (24) is deposited on the track layer (20) and into the openings (22) of the track layer. 9. The method according to claim 8, characterized in that the through openings (22) of the track layer (20) are formed by melting or peeling off the track layer with the aid of a light beam.