Methods and apparatus for rendering an optically encoded medium unreadable and tamper-resistant

• US 6,531,262 B1
• Filed: 10/17/2000
• Issued: 03/11/2003
• 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., Smuk, Andrei, Krieg-Kowald, Marianne
• Primary Examiner(s): ANGEBRANNDT, MARTIN J
• Application Number:
  US09/690,405
• Time in Patent Office: 875 Days
• Field of Search: 283/81, 283/86, 430/270.15, 430/270.1, 430/945, 369/286, 369/283, 369/275.1
• US Class Current: 430/270.15
• 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 20/00608 wherein the material that the record carrier is made of is altered, e.g. adding reactive dyes that alter the optical properties of a disc after prolonged exposure to light or air
• CPC Class Codes: G11B 20/00695 said measures preventing that data are read from the recording medium
• CPC Class Codes: G11B 20/0084 wherein the usage restriction can be expressed as a specific time or date
• CPC Class Codes: G11B 23/281 by changing the physical properties of the record carrier
• CPC Class Codes: G11B 7/005 Reproducing G11B7/0065 takes precedence
• CPC Class Codes: G11B 7/252 of layers other than recording layers
• CPC Class Codes: G11B 7/26 Apparatus or processes specially adapted for the manufacture of record carriers
• CPC Class Codes: Y10S 430/146 Laser beam

Abstract

Methods and apparatus are provided for making an optically readable media unreadable and tamper-resistant. A method has steps of (a) providing the media with a readout surface layer that is non-flat (i.e., textured in some way, such as by embossing, scratching, depositing a non-planar layer or regions, such as droplets) and that inhibits optical readout of the media; (b) applying a coating layer to the non-flat surface layer to smooth the non-flat surface and to enable optical readout of the media; and, after an initiation of a readout period, (c) removing the coating layer so as to expose the non-flat readout surface layer, thereby inhibiting optical readout of the media. Preferably, the coating layer is substantially index matched to the readout surface layer. The step of removing includes at least one of evaporating or subliming a component material of the coating layer A method is also disclosed for discouraging tampering with a readout-limiting mechanism by (a) providing the media with at least one layer that embodies the readout-limiting mechanism; (b) providing a textured surface that forms part of a layer that underlies the at least one layer, where the textured surface inhibits optical readout of the media; and (c) applying a coating layer over the textured surface to smooth the textured surface and to enable optical readout of the media, wherein removal of the coating layer exposes the textured surface thereby inhibiting optical readout of the media.

Claims

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

providing the media with a readout surface layer that is non-flat and that inhibits optical readout of the media;

applying a coating layer to the non-flat surface layer to smooth the non-flat surface and to enable optical readout of the media; and

after an initiation of a readout period, reducing the thickness of the coating layer so as to expose the non-flat readout surface layer, thereby inhibiting optical readout of the media.

2. A method as in claim 1, wherein the coating layer is substantially index matched to the readout surface layer.

3. A method as in claim 1, wherein the step of reducing the thickness comprises a step of evaporating at least one component material of the coating layer.

4. A method as in claim 1, wherein the step of reducing the thickness comprises a step of subliming at least one component material of the coating layer.

8. A method as in claim 2, wherein said coating layer changes from an optically transparent state to a state that inhibits successful readout of data structures located on the media.

5. A method for discouraging tampering with a readout-limiting mechanism of an optically readable media, comprising steps of:

providing the media with at least one layer that embodies the readout-limiting mechanism;

providing a textured surface that comprises a layer that underlies said at least one layer, said textured surface inhibiting optical readout of the media; and

applying a coating layer over said textured surface to smooth the textured surface and to enable optical readout of the media, wherein removal of the coating layer exposes the textured surface thereby inhibiting optical readout of the media;

wherein the readout-limiting mechanism comprises a layer that changes from a first state

that enables successful readout of data structures located on the media to a second state that inhibits successful readout of data structures located on the media; and

wherein said change to said second state is induced by an increase in optical absorption.

6. A method as in claim 5, wherein the readout-limiting mechanism layer changes from an optically transparent state to a state that inhibits successful readout of data structures located on the media.

7. A method as in claim 5, wherein the readout-limiting mechanism comprises said coating layer.

9. A method as in claim 5, wherein said change to said second state is further induced by an increase in mechanical stress.

10. A method as in claim 5, wherein said change to said second state is further induced by an increase in at least one of optical noise and wavefront aberration created by scattering.

11. A method as in claim 5, wherein the coating layer is substantially index matched to the textured surface layer.

12. A method for discouraging tampering with a readout-limiting mechanism of an optically readable media, comprising steps of:

providing the media with at least one layer that embodies the readout-limiting mechanism;

providing a textured surface that comprises a layer that underlies said at least one layer, said textured surface inhibiting optical readout of the media; and

applying a coating layer over said textured surface to smooth the textured surface and to enable optical readout of the media, wherein removal of the coating layer exposes the textured surface thereby inhibiting optical readout of the media;

wherein the readout-limiting mechanism comprises a layer that changes from a first state that enables successful readout of data structures located on the media to a second state that inhibits successful readout of data structures located on the media and,

wherein said change to said second state is induced by evaporation of a volatile compound.

13. A method for discouraging tampering with a readout-limiting mechanism of an optically readable media, comprising steps of:

providing the media with at least one layer that embodies the readout-limiting mechanism;

providing a textured surface that comprises a layer that underlies said at least one layer, said textured surface inhibiting optical readout of the media; and

applying a coating layer over said textured surface to smooth the textured surface and to enable optical readout of the media, wherein removal of the coating layer exposes the textured surface thereby inhibiting optical readout of the media;

wherein the readout-limiting mechanism comprises a layer that changes from a first state that enables successful readout of data structures located on the media to a second state that inhibits successful readout of data structures located on the media and,

wherein said change to said second state is induced by sublimation of a volatile compound.

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

providing the media with a first layer having a textured surface that would inhibit successful readout of the optically readable media;

coating the textured surface with a second layer that is comprised of a volatile component;

removing at least some of said volatile component for causing an increase in at least one of photoabsorption or scattering or surface roughness;

wherein

an attempt to remove the second layer results in exposure of the textured surface, thereby inhibiting successful readout of the optically readable media.

15. A method as in claim 14, wherein the step of removing at least some of the volatile component occurs through a barrier layer.

16. A method as in claim 14, wherein the step of removing at least some of the volatile component occurs after a step of removing a barrier layer.

17. A method as in claim 14, wherein the step of removing at least some of the volatile component occurs after a step of removing the media from a package that contains the volatile compound.

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

providing the media with a first layer having a textured surface that would inhibit successful readout of the optically readable media;

coating the textured surface with a second layer that is comprised of a volatile component; and

during a media play enablement period removing at least some of volatile component for reducing at least a thickness of the second layer; and

terminating the media play enablement period when the thickness of the second layer is reduced to a point that an exposure of the textured surface occurs, thereby inhibiting successful readout of the optically readable media.

19. A method as in claim 18, wherein the step of removing at least some of the volatile component occurs through a barrier layer, and where the barrier layer has a thickness that is predetermined for controlling a rate of transport of the volatile component through the barrier layer.

20. A method as in claim 18, wherein the step of removing at least some of the volatile component occurs after a step of removing a barrier layer.

21. A method as in claim 18, wherein the step of removing at least some of the volatile component occurs after a step of removing the media from a package that contains the volatile compound.

22. An optically readable media, comprising:

a region that encodes information that is optically readable by a reading device;

an overlying readout surface layer that is non-flat and that would inhibit the readout device from reading the information; and

a coating layer over said non-flat surface layer for smoothing the non-flat surface and enabling the readout device to read the information;

wherein

said coating layer is responsive to an initiation of a readout period for being reduced in thickness so as to expose at least a portion of the non-flat readout surface layer, thereby inhibiting the readout device from reading the information.

23. A media as in claim 22, wherein the coating layer is substantially index matched to the readout surface layer.

24. A media as in claim 22, wherein said coating layer is comprised of a volatile compound and is reduced in thickness by evaporation or sublimation of said volatile compound.

25. An optically readable media, comprising:

a region that encodes information that is optically readable by a reading device;

a transparent layer having a textured surface that overlies said region, said textured surface inhibiting optical readout of the media by the reading device; and

a readout-limiting layer that overlies said textured surface, said read-out limiting layer smoothing said textured surface and enabling, for the duration of a readout period, optical readout of the media by the readout device, wherein removal of the readout-limiting coating layer exposes said textured surface thereby inhibiting optical readout of the media by the readout device;

wherein the readout-limiting layer comprises material that changes from a first state that enables successful readout of data structures located on the surface regiori of the media to a second state that inhibits successful readout of the data structures located on the surface region of the media; and

wherein said change to said second state is induced by an increase in optical absorption.

26. A media as in claim 25, wherein the readout-limiting layer comprises material that changes from an optically transparent state to a state that inhibits successful readout of the surface region of the media.

27. A media as in claim 25, wherein said change to said second state is further induced by an increase in mechanical stress.

28. A media as in claim 25, wherein said change to said second state is further induced by an increase in optical scattering.

29. A media as in claim 25, wherein said readout-limiting layer is substantially index matched to said transparent layer.

30. An optically readable media, comprising:

a region that encodes information that is optically readable by a reading device;

a transparent layer having a textured surface that overlies said region, said textured surface inhibiting optical readout of the media by the reading device; and

a readout-limiting layer that overlies said textured surface, said read-out limiting layer smoothing said textured surface and enabling, for the duration of a readout period, optical readout of the media by the readout device, wherein removal of the readout-limiting coating layer exposes said textured surface thereby inhibiting optical readout of the media by the readout device;

wherein the readout-limiting layer comprises material that changes from a first state that enables successful readout of data structures located on the surface region of the media to a second state that inhibits successful readout of the data structures located on the surface region of the media and,

wherein said change to said second state is induced by evaporation or sublimation of a volatile compound.

31. An optically readable media, comprising:

a region that encodes information that is optically readable by a reading device;

a transparent layer having a textured surface that overlies said region, said textured surface inhibiting optical readout of the media by the reading device; and

a readout-limiting layer that overlies said textured surface, said read-out limiting layer smoothing said textured surface and enabling, for the duration of a readout period, optical readout of the media by the readout device, wherein removal of the readout-limiting coating layer exposes said textured surface thereby inhibiting optical readout of the media by the readout device, wherein at least one layer is comprised of a volatile substance, and further comprising a barrier layer for isolating said at least one layer from a surrounding medium.

32. An optically readable media, comprising:

a region that encodes information that is optically readable by a reading device;

a transparent layer having a textured surface that overlies said region, said textured surface inhibiting optical readout of the media by the reading device; and

a readout-limiting layer that overlies said textured surface, said read-out limiting layer smoothing said textured surface and enabling, for the duration of a readout period, optical readout of the media by the readout device, wherein removal of the readout-limiting coating layer exposes said textured surface thereby inhibiting optical readout of the media by the readout device, wherein at least one layer is comprised of a volatile substance, and further comprising a peel-off barrier layer for isolating said at least one layer from a surrounding medium at least until it is desired to use the media in the readout device.

33. An optically readable disk, comprising:

a readout surface through which a readout device is able to read information;

a plurality of three dimensional features disposed on said readout surface, said features inhibiting optical readout of said disk by the reading device;

a color forming layer disposed over said readout surface and at least partially covering said features; and

an outer layer disposed over said color forming layer, wherein said features are completely covered by said color forming layer and said outer layer, and wherein the presence of said color forming layer and said outer layer enables optical readout of said disk by the reading device.

34. An optically readable disk as in claim 33, wherein said color forming layer comprises a volatile compound that enters a surrounding medium via a transport mechanism driven by a concentration gradient between said color forming layer and the surrounding medium.

35. An optically readable disk as in claim 34, wherein a thickness of said outer layer is selected at least in part on a desired amount of time that said disk is to remain in a readable condition after the initiation of said transport mechanism.

36. An optically readable disk as in claim 34, wherein said disk is sealed in a container with a source of said volatile compound.

37. An optically readable disk as in claim 34, wherein said disk further comprises a peel-off barrier layer to prevent transport of said volatile compound through said outer layer.

38. An optically readable disk as in claim 33, wherein said disk comprises an optically detectable taggant compound.

39. An optically readable disk as in claim 33, wherein said color forming layer exhibits an absorption maximum corresponding to one readout wavelength.

40. An optically readable disk as in claim 33, wherein said color forming layer exhibits a plurality of absorption maximum corresponding to a plurality of readout wavelengths.

41. An optically readable disk as in claim 33, wherein removal of all or a portion of a thickness of said color forming layer exposes at least some of said three dimensional features for subsequently inhibiting optical readout of the disk by the reading device.

42. An optically readable disk as in claim 33, wherein said color forming layer comprises at least one chromophore that bias said color forming layer so as to reduce an amount of time required for said color forming layer to transition from a state where said disk is readable to a state where said disk in unreadable.

43. A method of fabricating a limited play optically readable disk, comprising steps of:

providing a disk having a readout surface through which a readout device is able to read information;

forming a plurality of three dimensional features at said readout surface, said features inhibiting optical readout of said disk by the reading device;

forming a color forming layer disposed over said readout surface and at least partially covering said features; and

forming an outer layer disposed over said color forming layer, wherein said features are completely covered by said color forming layer and said outer layer, and wherein the presence of said color forming layer and said outer layer enables optical readout of said disk by the reading device.

44. A method for setting a duration of a limited play period of an optically readable disk, comprising steps of:

constructing the disk to include at least one limited play region comprised of a volatile compound, the limited play region operating by volatile compound transport driven by a concentration gradient between the region and a surrounding medium; and

adjusting the duration of the limited play period by setting a thickness of a transport barrier layer that overlies the region;

the step of adjusting comprising a further step of adding a bias chromophore in combination with a color forming layer in the limited play region.

45. A method as in claim 44, where said bias chromophore is selected to absorb light at a desired wavelength for causing the color forming layer to exhibit some amount of absorption that is less than a maximum amount of absorption that is tolerated by a readout device before the optically readable disk becomes unreadable.

46. A method as in claim 44, where said bias chromophore is selected to absorb light at a desired wavelength for causing transmission of light through the color forming layer to not asymptotically approach a readability threshold.

47. A method as in claims 44, where said bias chromophore is selected, for use with a readout device that employs about a 650 nm readout wavelength, to comprise 3-Diethylyamino-7-diethyliminophenoxazonium perchlorate.