Method and apparatus for protection of data carrying discs
View Patent ↗The method and apparatus described utilise the fact that CDs manufactured from the same master will have distinctive physical characteristics attributable to the physical manufacturing process of the master to distinguish counterfeit CDs from genuine discs. For a genuine disc, the relative angular orientation of specified sections of the recorded data are determined and recorded. The relative angular orientation of the same sections of data on a test disc are also determined. Where the relative angular orientations are the same it is concluded that the test disc derives from the same source as the genuine disc and is therefore bona fide. Where there is no correlation, the test disc may be identified as counterfeit. The relative angular orientations, or other physical characteristics of the discs, may be physically measured, or may be calculated from information gained by reading the data on the disc. The disclosed technique can also be used to copy protect discs.
1. A method of protecting a data carrying disc, the method comprising:
recording selected data onto a data carrying genuine disc, and
predetermining the physical characteristics of said selected data on the data carrying genuine disc;
wherein a copy of the genuine disc can be played successfully, and by measuring the predetermined physical characteristics the copy is distinguished from the genuine disc.
2. A method according to claim 1 , wherein the physical characteristics of the genuine disc which are predetermined are the locations of the selected data on said disc.
3. A method according to claim 2 , further comprising recording said selected data at predetermined relative angular orientations on the genuine disc.
4. A method according to claim 3 , wherein the selected data recorded on the genuine disc is arranged to lie substantially on a single radius of the disc.
5. A method according to claim 2 , wherein the selected data whose physical characteristics are predetermined are selected frames of the data recorded on each the genuine disc.
6. A method according to claim 1 , wherein the selected data whose physical characteristics are predetermined are selected frames of the data recorded on the genuine disc.
7. A method according to claim 6 or claim 5 , wherein the selected frames of data are arranged at evenly spaced radial positions on the genuine disc.
8. A method of copy protecting a data carrying disc according to claim 1 , the method further comprising:
writing the selected data to the disc at a bit rate controlled in dependence upon the predetermined physical characteristics of the selected data, whereby the selected data is written at predetermined locations on the disc.
9. A method of according to claim 1 , the method further comprising:
rotating the genuine disc during the writing of data thereto;
writing the selected data to the disc as it is rotated; and
controlling the speed of rotation of the disc in dependence upon the predetermined physical characteristics of the selected data whereby the selected data is written at predetermined locations on the disc.
10. A method according to claim 9 , the method further comprising:
continuously monitoring the speed of rotation of the disc to determine actual locations where the selected data is being written;
comparing the actual location of selected data with the predetermined location; and
adjusting the speed of rotation of the disc to cause actual and predetermined locations to converge.
11. A method according to claim 10 , the method further comprising:
writing the selected data to the genuine disc at a bit rate controlled in dependence upon the predetermined physical characteristics of the selected data, whereby the selected data is written at predetermined locations on the disc.
12. A method according to claim 1 , the method further comprising:
rotating the genuine disc during the writing of data thereto;
writing the selected data to the disc as it is rotated; and
controlling the speed of rotation of the disc in dependence upon the predetermined physical characteristics of the selected data whereby the selected data is written at predetermined locations on the disc;
and the method further comprising:
writing the selected data to the disc by way of a laser beam recorder generating a bit stream representing the selected data,
wherein the rate of said bit stream is synchronised to the speed of rotation of the disc.
13. A method according to claim 12 , the method further comprising:
continuously monitoring the speed of rotation of the genuine disc to determine actual locations where the selected data is being written;
comparing the actual location of selected data with the predetermined location; and
adjusting the speed of rotation of the disc to cause actual and predetermined locations to converge.
14. A protected data carrying genuine disc, wherein the disc has data recorded thereon, and wherein, to provide protection, selected data has been recorded onto the disc to have predetermined physical characteristics and wherein a copy of the genuine disc can be played successfully, and by measuring the predetermined physical characteristics the copy is distinguished from the genuine disc.
15. A disc according to claim 14 , wherein the physical characteristics of the genuine disc which are predetermined are the locations of the selected data on the disc.
16. A disc according to claim 15 , wherein the physical characteristics of the genuine disc which are predetermined are the angular orientations of the selected data on the disc.
17. A disc according to claim 16 , wherein the selected data recorded on the genuine disc is arranged to lie substantially on a single radius of the disc.
18. A disc according to claim 14 , wherein the selected data whose physical characteristics are predetermined are selected frames of the data recorded on the genuine disc.
19. A disc according to claim 18 , wherein the selected frames of data are at evenly spaced radial positions on the genuine disc.
20. Apparatus for producing a protected data carrying disc, said apparatus comprising:
a writing apparatus for writing data to a genuine disc,
a drive for rotating the disc as it is written, and
means for controlling the writing apparatus and the drive such that selected data is written to the genuine disc to have predetermined characteristics wherein a copy of the genuine disc can be played successfully, and by measuring the predetermined characteristics the copy is distinguished from the genuine disc.
21. Apparatus according to claim 20 , wherein the means for controlling is arranged to control the speed of rotation of the genuine disc whereby the selected data is written at predetermined locations on the disc.
22. Apparatus according to claim 21 , further comprising means for comparing the actual location of selected data written to the genuine disc with the predetermined location, the means for comparing being arranged to adjust the speed of rotation of the disc to cause said actual and predetermined locations to coincide.
23. Apparatus for producing a protected data carrying disc, said apparatus comprising:
a processor,
a signal encoder coupled to the processor to receive data therefrom, and laser optics coupled to the signal encoder to receive encoded data therefrom, the laser optics being arranged to write the encoded data to a genuine disc,
a controllable drive arranged to rotate the disc to be written, the drive being controlled by said processor, and
a sensor associated with the controllable drive and arranged to provide information about the disc rotation speed and/or angular orientation to said drive,
wherein the processor is arranged to ensure that selected data is written to predetermined locations on the disc and wherein a copy of the genuine disc can be played successfully, and by measuring the predetermined physical characteristics the copy is distinguished from the genuine disc.
24. Apparatus according to claim 23 , further comprising a clock generator, controlled by the processor, for applying clock signals to the signal encoder.
25. Apparatus according to claim 24 , wherein the clock signals applied to the signal encoder are synchronised with the rotation speed of the genuine disc rotated by said drive.
26. Apparatus according to claim 23 , wherein the sensor is a motor speed sensor and is arranged to apply control signals to said controllable drive.
27. A method of copy protecting a data carrying disc, the method comprising:
recording selected data onto a data carrying genuine disc,
predetermining the physical characteristics of said selected data on the data carrying disc;
wherein the physical characteristics of said the genuine disc which are predetermined are the locations of the selected data on said disc; and
further comprising recording said selected data at predetermined relative angular orientations on said disc.
28. A method of copy protecting a data carrying disc, the method comprising:
recording selected data onto a data carrying genuine disc,
predetermining the physical characteristics of said selected data on the data carrying disc;
wherein the selected data whose physical characteristics are predetermined are selected frames of the data recorded on said disc, and wherein the selected frames of data are arranged at evenly spaced radial positions on said disc.
29. A method of copy protecting a data carrying disc, the method comprising:
recording selected data onto a data carrying genuine disc,
predetermining the physical characteristics of said selected data on the data carrying disc;
rotating the disc during the writing of data thereto;
writing the selected data to the disc as it is rotated; and
controlling the speed of rotation of the disc in dependence upon the predetermined physical characteristics of the selected data whereby the selected data is written at predetermined locations on the disc.
30. A method of copy protecting a data carrying disc, the method comprising:
recording selected data onto a data carrying genuine disc,
predetermining the physical characteristics of said selected data on the data carrying disc;
rotating the disc during the writing of data thereto;
writing the selected data to the disc as it is rotated; and
controlling the speed of rotation of the disc in dependence upon the predetermined physical characteristics of the selected data whereby the selected data is written at predetermined locations on the disc;
and the method further comprising:
writing the selected data to the disc by way of a laser beam recorder generating a bit stream representing the selected data,
wherein the rate of said bit stream is synchronised to the speed of rotation of the disc.
31. A copy protected data carrying disc, wherein the disc has data recorded thereon, and wherein, to provide copy protection, selected data has been recorded onto the disc to have predetermined physical characteristics;
wherein the physical characteristics of said disc which are predetermined are the locations of the selected data on the disc; and
wherein the physical characteristics of the disc which are predetermined are the angular orientations of the selected data on the disc.
32. A copy protected data carrying disc, wherein the disc has data recorded thereon, and wherein, to provide copy protection, selected data has been recorded onto the disc to have predetermined physical characteristics;
wherein the selected data whose physical characteristics are predetermined are selected frames of the data recorded on the disc, and wherein the selected frames of data are at evenly spaced radial positions on said disc.
33. Apparatus for producing a copy protected data carrying disc, said apparatus comprising:
a writing apparatus for writing data to a disc,
a drive for rotating the disc as it is written, and
control means for controlling the writing apparatus and the drive such that selected data is written to the disc to have predetermined characteristics;
wherein the control means is arranged to control the speed of rotation of the disc whereby the selected data is written at predetermined locations on the disc.
34. Apparatus for producing a copy protected data carrying disc, said apparatus comprising:
a processor,
a signal encoder coupled to the processor to receive data therefrom, laser optics coupled to the signal encoder to receive encoded data therefrom, the laser optics being arranged to write the encoded data to a disc,
a controllable drive arranged to rotate the disc to be written, the drive being controlled by said processor,
a sensor associated with the controllable drive and arranged to provide information about the disc rotation speed and/or angular orientation to said drive,
wherein the processor is arranged to ensure that selected data is written to predetermined locations on the disc; and
a clock generator, controlled by the processor, for applying clock signals to the signal encoder;
wherein the clock signals applied to the signal encoder are synchronised with the rotation speed of the disc rotated by said drive.