EP0107379A1
Expired / Lapsed
EP
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Data storage medium
Assignee: Plasmon Data Systems NV
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Filing: 1983-09-27
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Granted: —
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Expires: 2003-09-27
Abstract
Abstract A data storage medium is provided which is suitable for production or replication by moulding, casting, embossing or a similar process against a tool. The data storage medium has a surface or a surface region which is strongly absorbent of at least a predetermined band of wavelengths of electromagnetic radiation. The surface or surface region includes a layer of a heat sensitive material which has a textured surface pattern the pitch of which is smaller than the shortest wavelength of the predetermined band of wavelengths, and the depth (peak-to-trough) of which is at least 100 nm. The surface pattern is free from undercutting, and can comprise an array of protuberances or one or more sets of grooves (which may be intersecting). The textured surface pattern is further coated with a thin film of a high-opacity material, e.g. gold, the thickness of the overcoating preferably being such as to give no more than 10% transmission of incident radiation. A tool for use in producing such a data storage medium, and methods of using the tool, are also disclosed. The data storage medium may be prepared in blank form for use as the consumer desires, or it may be pre-recorded in part or in entirety.
Inventors
- 👤 Robert Martin Pettigrew
- 👤 Victor Carey Humberstone
- 👤 Keith Gardner
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 03:55
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/241; G11B7/252; G11B7/253; G11B7/2533; G11B7/242; G11B7/244; G11B7/245; G11B7/257; G11B7/2578; G11B2007/25705; G11B2007/25706; G11B2007/25708; G11B7/2534; Y; Y10; Y10S; Y10S428/00; Y10S428/913; Y10S430/00; Y10S430/146; Y10T; Y10T156/00; Y10T156/10; Y10T156/1002; Y10T156/1039; Y10T156/1041; Y10T428/00; Y10T428/12; Y10T428/12472; Y10T428/26; Y10T428/261
Claims Analysis
Total Claims: 38
Claim 1
Independent Claim
137 words
A data storage medium having a surface or a surface region which is strongly absorbent of at least a predetermined band of wavelengths of electromagnetic radiation, whereby the surface or surface region can be written-upon by such radiation, the said surface or surface region including a layer of heat sensitive material which has a textured surface pattern the pitch of which is smaller than the shortest wavelength within said predetermined band of wavelengths, and the depth (peak-to-trough) of which pattern is at least 100 nm, the textured surface pattern being free from undercutting so as to be suitable for production or replication by moulding, casting, embossing or similar process against a tool, and the textured surface pattern being overcoated with a thin film of a material which has a high opacity at the predetermined band of wavelengths.
Claim 2
Dependent Claim
137 words
A data storage medium having a surface or a surface region which is strongly absorbent of at least a predetermined band of wavelengths of electromagnetic radiation, whereby the surface or surface region can be written-upon by such radiation, the said surface or surface region including a layer of heat sensitive material which has a textured surface pattern the pitch of which is smaller than the shortest wavelength within said predetermined band of wavelengths, and the depth (peak-to-trough) of which pattern is at least 100 nm, the textured surface pattern being free from undercutting so as to be suitable for production or replication by moulding, casting, embossing or similar process against a tool, and the textured surface pattern being overcoated with a thin film of a material which has a high opacity at the predetermined band of wavelengths.
Claim 3
Dependent Claim
25 words
A data storage medium as claimed in claim 1, wherein said textured surface pattern extends over substantially one entire surface of the data storage medium.
Claim 4
Dependent Claim
28 words
A data storage medium as claimed in claim 1, wherein said textured surface pattern is present in one or more selected surface regions of the data storage medium.
Claim 5
Dependent Claim
21 words
A data storage medium as claimed in claim 1, 2 or 3, wherein the heat sensitive material is a plastics material.
Claim 6
Dependent Claim
30 words
A data storage medium as claimed in claim 4, wherein the plastics material is one which undergoes a large volume change when degraded from the polymeric state to monomeric species.
Claim 7
Dependent Claim
22 words
A data storage medium as claimed in claim 5, wherein the plastics material is poly(methylstyrene), polyformaldehyde, polymethacrylic acid or a polymethacrylic ester.
Claim 8
Dependent Claim
21 words
A data storage medium as claimed in claim 4, wherein the plastics material is a polycarbonate, a polyester or poly(vinyl chloride).
Claim 9
Dependent Claim
20 words
A data storage medium as claimed in any preceding claimed, wherein the textured surface pattern comprises an array of protuberances.
Claim 10
Dependent Claim
20 words
A data storage medium as claimed in any preceding claim, wherein the textured surface pattern comprises an arrangement of grooves.
Claim 11
Dependent Claim
21 words
A data storage medium as claimed in any claim 9, wherein the textured surface pattern comprises an array of parallel grooves.
Claim 12
Dependent Claim
17 words
A data storage medium as claimed in claim 10, wherein the parallel grooves are of square cross-section.
Claim 13
Dependent Claim
17 words
A data storage medium as claimed in claim 10, wherein the parallel grooves are of triangular cross-section.
Claim 14
Dependent Claim
17 words
A data storage medium as claimed in claim 10, wherein the parallel grooves are of sinusoidal cross-section.
Claim 15
Dependent Claim
17 words
A data storage medium as claimed in claim 10, wherein the parallel grooves are of saw-toothed form.
Claim 16
Dependent Claim
25 words
A data storage medium as claimed in any one of claims 9 to 14, wherein the textured surface pattern comprises an array of concentric grooves.
Claim 17
Dependent Claim
25 words
A data storage medium as claimed in any one of claims 9 to 15, wherein the textured surface pattern comprises an array of radial grooves.
Claim 18
Dependent Claim
25 words
A data storage medium as claimed in any one of claims 9 to 16, wherein the textured surface pattern comprises one or more spiral grooves.
Claim 19
Dependent Claim
25 words
A data storage medium as claimed in any one of claims 9 to 17, wherein the textured surface pattern includes two sets of superimposed grooves.
Claim 20
Dependent Claim
35 words
A data storage medium as claimed in claim 18, wherein the two sets of grooves each consist of an array of parallel grooves, the textured surface pattern being in the form of a crossed grating.
Claim 21
Dependent Claim
17 words
A data storage medium as claimed in claim 19, wherein the two sets of grooves intersect orthogonally.
Claim 22
Dependent Claim
22 words
A data storage medium as claimed in claim 13, wherein the grooves have a configuration which is substantially a single sine wave.
Claim 23
Dependent Claim
23 words
A data storage medium as claimed in any preceding claim wherein the pitch of the textured surface pattern is less than 300 nm.
Claim 24
Dependent Claim
23 words
A data storage medium as claimed in any preceding claim, wherein the depth of the textured surface pattern is at least 200 nm.
Claim 25
Dependent Claim
21 words
A data storage medium as claimed in claim 23, wherein the depth of the textured surface pattern is about 400 nm.
Claim 26
Dependent Claim
22 words
A data storage medium as claimed in any preceding claim, wherein the material which constitutes the high-opacity thin film is a metal.
Claim 27
Dependent Claim
43 words
A data storage medium as claimed in claim 25, wherein the thickness of said thin film is such as to give a transmission of no more than about 20%, preferably no more than 10%, of incident radiation over the predetermined band of wavelengths.
Claim 28
Dependent Claim
22 words
A data storage medium as claimed in claim 25 or 26, wherein said high-opacity material is gold or an alloy of gold.
Claim 29
Dependent Claim
22 words
A data storage medium as claimed in claim 25 or 26, wherein said high-opacity material is aluminium, chromium, titanium, silver or tellurium.
Claim 30
Dependent Claim
23 words
A data storage medium as claimed in any preceding claim, wherein the medium is in the form of a disk, rectangle or tape.
Claim 31
Dependent Claim
32 words
A method of manufacturing a data storage medium as claimed in claim 1, the method including producing said textured surface pattern by plastics moulding, casting, embossing or similar process against a tool.
Claim 32
Dependent Claim
121 words
A method according to claim 30, wherein the textured surface pattern is generated by the steps of: (a) depositing a thin film of a resist onto a smooth surfaced substrate; (b) exposing the resist in a pattern corresponding to that desired in the data storage medium; (c) developing the resist; (d) generating a negative replica of the resist surface by coating said resist surface with a thin electrically conductive layer and thereafter electroplating onto that layer a further layer of metal thick enough to be durable; (e) stripping the resist from the metal layers; and (f) forming a plastics replica from the patterned surface of said metal layers by moulding, casting, embossing or stamping a plastics material against said patterned surface.
Claim 33
Dependent Claim
20 words
A method according to claim 31, wherein the exposure pattern for the resist is generated by a laser interference technique.
Claim 34
Dependent Claim
28 words
A method according to claim 32, wherein the resist-coated substrate is moved by rotation and/or translation underneath the laser interference pattern in order to generate the desired exposure.
Claim 35
Dependent Claim
30 words
A method according to claim 31, wherein the desired exposure pattern for the resist is generated by forming diffraction patterns on the surface of the resist with a diffraction grating.
Claim 36
Dependent Claim
25 words
A method according to claim 31, wherein the resist is an electron beam resist, and wherein the desired pattern is generated by electron beam writing.
Claim 37
Dependent Claim
37 words
A tool for use in producing a data storage medium as claimed in claim 1, by a method according to claim 30, the tool having a surface which is a negative image of said textured surface pattern.
Claim 38
Dependent Claim
39 words
A pre-recorded data carrying medium formed by selective irradiation of a data storage medium as claimed in claim 1, the pattern or patterns of irradiation being such as to permit the stored data to be regenerated in visual form.
References Cited (Backward Citations)
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