Methods and apparatus for rendering an optically encoded medium unreadable

• US 6,338,933 B1
• Filed: 06/24/1999
• Issued: 01/15/2002
• Est. Priority Date: 06/25/1998
• Status: Expired due to Fees

• Current Assignee: Flexplay Technologies
• Original Assignee: SpectraDisc Corporation (Flexplay Technologies)
• Inventors: Lawandy, Nabil M., Zepp, Charles M., Norland, Kenneth S.
• Primary Examiner(s): Angebranndt, Martin
• Application Number:
  US09/338,959
• Time in Patent Office: 936 Days
• Field of Search: 369/286, 369/283, 369/275.1, 430/19, 430/270.15, 430/270.1, 430/945
• US Class Current: 430/270.1
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/00797 wherein the usage restriction limits the number of times a content can be reproduced, e.g. using playback counters
• CPC Class Codes: G11B 23/282 Limited play
• CPC Class Codes: G11B 23/505 of disk carriers
• CPC Class Codes: G11B 7/252 of layers other than recording layers
• CPC Class Codes: G11B 7/2534 polycarbonates [PC]
• CPC Class Codes: G11B 7/2542 consisting essentially of organic resins
• CPC Class Codes: G11B 7/2575 resins
• CPC Class Codes: G11B 7/2585 based on aluminium
• CPC Class Codes: Y10S 430/146 Laser beam

Abstract

Methods and apparatus are provided for making an optically readable media unreadable. The method includes steps of (a) providing the media with an optically activated mechanism that degrades the reflectivity of a surface wherein information is encoded; (b) exposing the media to optical radiation for reading out the information; and, during the step of exposing, (c) initiating the operation of the optically activated mechanism. In this embodiment the step of initiating includes steps of (d) generating singlet oxygen in a layer disposed on the media; and (e) reacting the singlet oxygen with a metal-containing layer for oxidizing the surface of the metal-containing layer, thereby degrading the reflectivity of the surface. In a further aspect the optically activated mechanism causes a defocusing of a readout beam, thereby degrading reflection of the readout beam from a surface wherein information is encoded. In another embodiment the method deforms a surface of the layer resulting in readout beam aberration or in an inability to correctly stay on track. In another embodiment a portion of the surface is removed to the atmosphere, such as by evaporation of sublimation. In this embodiment a layer of the media is comprised of a volatile component and at least one other component. Removing at least some of volatile component by evaporation or sublimation causes an increase in at least one of photoabsorption or scattering or surface roughness with the remaining component, thereby rendering at least a portion of encoded information of the media unreadable, or affecting the tracking operation.

Claims

1. A method for intentionally making an optically readable media unreadable by a play process, comprising steps of:

providing the media with an optically activated mechanism that causes a defocusing of a readout beam, thereby degrading reflection of the readout beam from a surface wherein information is encoded;

exposing the media to optical radiation for reading out the information; and

during the step of exposing, initiating the operation of the optically activated mechanism;

wherein the step of initiating comprises steps of,

generating an optical intensity gradient in a layer disposed on the media; and

in response to the generated optical intensity gradient, deforming a surface of the layer resulting in at least one of readout beam aberration or a degradation of a readout tracking function, wherein the step of providing provides the layer so as to comprise an azobenzene containing polymer.

2. A method for intentionally making an optically readable media unreadable by a play process, comprising steps of:

providing the media with an optically activated mechanism that causes a defocusing of a readout beam, thereby degrading reflection of the readout beam from a surface wherein information is encoded;

exposing the media to optical radiation for reading out the information; and

during the step of exposing, initiating the operation of the optically activated mechanism,

wherein the step of initiating is comprised of steps of,

irradiating a photocurable polymer region that comprises the media; and

in response to the irradiation, photopolymerizing the polymer, thereby changing an index of refraction of the polymer resulting in readout beam aberration.

3. An optically readable media capable of intentionally being made unreadable by a play process, said media comprising an optically activated mechanism that is responsive to light used to readout information for defocusing a readout beam, thereby degrading reflection of the readout beam from a surface wherein information is encoded, wherein said mechanism is comprised of a layer of polymer that is responsive to an optical intensity gradient generated by said readout beam for deforming a surface of said layer, resulting in readout beam aberration, wherein said layer comprises an azobenzene containing polymer.

4. An optically readable media capable of intentionally being made unreadable by a play process, said media comprising an optically activated mechanism that is responsive to light used to readout information for defocusing a readout beam, thereby degrading reflection of the readout beam from a surface wherein information is encoded, wherein said mechanism is comprised of at least one region comprised of photoresponsive polymer that is responsive to the readout beam for being photopolymerized, thereby changing an index of refraction of the photocurable polymer resulting in readout beam aberration.

5. A method for intentionally making an optically readable media unreadable, comprising steps of:

providing the media with a layer that is comprised of a volatile component and at least one other component;

removing at least some of the volatile component from the layer; and

causing an increase in at least one of photoabsorption or scattering or surface roughness with the remaining component.

6. A method as in claim 5, wherein the other component is comprised of a lactone dye.

7. A method as in claim 5, wherein the other component is comprised of crystal violet lactone.

8. A method as in claim 5, wherein the layer is comprised of poly-p-(hydroxystyrene), ethanol, crystal violet lactone and N-methyl pyrrolidinone.

9. A method as in claim 5, wherein the layer is comprised of poly-p-(hydroxystyrene), ethanol, crystal violet lactone, ammonia, N-methyl pyrrolidinone, and formaldehyde.

10. A method as in claim 5, wherein the layer is comprised of cellulose acetate butyrate, ethyl acetate, silica gel, and benzyl alcohol.

11. A method as in claim 5, wherein the layer is comprised of a salt of a volatile amine, a non-volatile acid component and a lactone dye.

12. A method as in claim 5, wherein the layer is comprised of a salt of a volatile amine, a non-volatile acid component and a pH indicator dye.

13. A method as in claim 5, wherein the layer is comprised of a water damp polymer film containing a pH indicator dye, wherein during storage the layer is exposed to an atmosphere of a gas whose water solution is one of acidic or basic, and wherein upon removal from storage a volatile gas evaporates from the water damp film, and the pH changes causing a color change in the pH indicator dye.

14. A method as in claim 5, and further comprising a preliminary step of constructing the layer as a separate component layer, and then a step applying the separate component layer to a surface of the optically readable media.

15. A method for intentionally making an optically readable media unreadable, comprising steps of:

providing the media with a layer that is comprised of a sensitive inorganic material;

exposing the layer to an atmosphere containing carbon dioxide; and

reacting the inorganic material with the carbon dioxide to cause an increase in at least one of photoabsorption or scattering or surface roughness.

16. An optically readable media comprising a patterned structure for encoding information that can be readout by application of light, said optically readable media further comprising a layer that is comprised of a volatile component and at least one other components, wherein removing at least some of the volatile component from the layer causes an increase in at least one of photoabsorption or scattering or surface roughness with the remaining component, thereby rendering at least a portion of the encoded information unreadable.

17. A media as in claim 16, wherein the other component is comprised of a lactone dye.

18. A media as in claim 16, wherein the other component is comprised of crystal violet lactone.

19. A media as in claim 16, wherein the layer is comprised of poly-p-(hydroxystyrene), ethanol, crystal violet lactone and N-methyl pyrrolidinone.

20. A media as in claim 16, wherein the layer is comprised of poly-p-(hydroxystyrene), ethanol, crystal violet lactone, ammonia, N-methyl pyrrolidinone, and formaldehyde.

21. A media as in claim 16, wherein the layer is comprised of cellulose acetate butyrate, ethyl acetate, silica gel, and benzyl alcohol.

22. A media as in claim 16, wherein the layer is comprised of a salt of a volatile amine, a non-volatile acid component and a lactone dye.

23. A media as in claim 16, wherein the layer is comprised of a salt of a volatile amine, a non-volatile acid component and a pH indicator dye.

24. A media as in claim 16, wherein the layer is comprised of a water damp polymer film containing a pH indicator dye, wherein during storage the layer is exposed to an atmosphere of a gas whose water solution is one of acidic or basic, and wherein upon removal from storage a volatile gas evaporates from the water damp film, and the pH changes causing a color change in the pH indicator dye.

25. A media as in claim 16, wherein said layer is applied by one of a coating or printing process or as an adhesively affixed separate component layer.

26. An optically readable media comprising a patterned structure for encoding information that can be readout by application of light, said optically readable media further comprising a layer that is comprised of a sensitive inorganic material wherein exposure of said layer to an atmosphere containing carbon dioxide causes a reaction between the inorganic material and the carbon dioxide to cause an increase in at least one of photoabsorption or scattering or surface roughness, thereby rendering at least a portion of the encoded information unreadable.

27. A method for preparing an optically readable disk to become optically unreadable after a period of time for intentionally limiting the usable lifetime of the disk, comprising steps of:

providing a disk having a surface with optically readable features;

spin coating a first layer over the surface, the first layer being comprised of a volatile compound and at least one other compound, wherein as a result of an

evaporative process the removal of at least some of the volatile compound from the first layer results in a chemical reaction occurring in the at least one other compound, the chemical reaction causing an increase in photoabsorption in the first layer to light from a disk readout mechanism; and

applying an overlayer over the first layer, the overlayer being sufficiently permeable so as to allow the evaporative process to occur.

28. A method as in claim 27, and further comprising a step of storing the disk in an enclosure that also contains a quantity of the volatile compound in order to inhibit the occurrence of the chemical reaction while the disk is stored in the enclosure.

29. A method as in claim 28, wherein the volatile compound is comprised of N-methyl pyrrolidinone (NMP).

30. An optically readable disk that becomes optically unreadable after a period of time for intentionally limiting the usable lifetime of the disk, comprising steps of:

a disk substrate supporting a surface with optically readable features;

a first layer disposed above the surface, the first layer being comprised of a volatile compound and at least one other compound, wherein as a result of an evaporative process the removal of at least some of the volatile compound from the first layer results in a chemical reaction occurring in the at least one other compound, the chemical reaction causing an increase in photoabsorption in the first layer to light from a disk readout mechanism; and

an overlayer disposed above the first layer, the overlayer being sufficiently permeable so as to allow the evaporative process to occur.

31. A disk as in claim 30, wherein the disk is stored prior to the first use in an enclosure that also contains a quantity of the volatile compound in order to inhibit the occurrence of the chemical reaction while the disk is stored in the enclosure.

32. A disk as in claim 30, wherein the volatile compound is comprised of N-methyl pyrrolidinone (NMP).