Varying the rate at which data appear on an optical disc rotated at a constant linear velocity to prevent unauthorized duplication of the disc

• US 6,477,124 B2
• Filed: 05/18/2001
• Issued: 11/05/2002
• Est. Priority Date: 11/15/2000
• Status: Expired due to Term

• Current Assignee: Doug Carson & Associates, Inc.
• Original Assignee: Doug Carson & Associates, Inc.
• Inventors: Carson, Douglas M.
• Primary Examiner(s): Tran, Thang V.
• Application Number:
  US09/860,791
• Publication Number:
  US 20020126606A1
• Time in Patent Office: 536 Days
• Field of Search: 369/53.21, 369/275.3, 369/47.12, 369/47.29, 369/47.38, 369/47.45, 369/47.43, 369/30.05, 369/30.19, 369/84
• US Class Current: 369/53.21
• 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 7/0079 Zoned data area, e.g. having different data structures or formats for the user data within data layer, Zone Constant Linear Velocity [ZCLV], Zone Constant Angular Velocity [ZCAV], carriers with RAM and ROM areas

Abstract

Apparatus and method for recording data to an optical disc to prevent unauthorized duplication of the disc. The disc includes a data placement zone to which first data are written at a first data rate as the disc is rotated at a selected linear velocity. The disc further includes a velocity disruption zone to which second data are written at a second different data rate as the disc is rotated at the selected linear velocity. The variation in frequency between the first and second data rates preferably causes a readback system to lose frequency lock on the second data during a continuous access operation on the first and second data. An unauthorized disc can also be detected by comparing the disc linear velocity as the second data are accessed to a target linear velocity. Access to the disc can be denied when a velocity mismatch is detected.

Claims

1. An optical disc to which data are recorded in the form of optically detectable patterns for subsequent access by a disc readback system having a motor configured to rotate the disc at a nominally constant linear velocity, a readback head assembly configured to transduce the optically detectable patterns and readback recovery circuitry configured to obtain frequency lock on a frequency of the optically detectable patterns, the disc comprising:

a data placement zone to which first data are written to produce a first data rate as a frequency at which the first data pass the readback head assembly as the disc is rotated at a selected linear velocity; and

a velocity disruption zone adjacent the data placement zone to which second data are written to produce a second data rate as a frequency at which the second data pass the readback head assembly as the disc is rotated at the selected linear velocity, wherein variation in frequency between the first and second data rates is selected to cause the recovery circuitry, having obtained frequency lock on the first data as the first data are retrieved, to subsequently lose frequency lock on the second data as the readback system attempts to sequentially read the first and second data during a continuous access operation.

2. The optical disc of claim 1, wherein the second data are separately accessed from the first data while the disc is rotated at a second disc linear velocity different from the selected disc linear velocity.

3. The optical disc of claim 1, wherein the first and second data are both used by a user of the optical disc and are accessed during separate access operations.

4. The optical disc of claim 1, further comprising a data rate profile zone to which data rate profile information is stored in relation to the variation in frequency between the first and second data rates.

5. The optical disc of claim 4, wherein the data rate profile information includes information indicative of a target linear velocity of the disc sufficient to enable the recovery circuitry to obtain frequency lock on the second data, the data rate profile information facilitating disc authentication by the readback system through steps of measuring the disc linear velocity as the second data are accessed and comparing the measured disc linear velocity with the target linear velocity, and denying further disc access when a mismatch is detected between the measured and target disc linear velocities.

6. An optical disc to which data are recorded in the form of optically detectable patterns for subsequent access by a disc readback system having a motor configured to rotate the disc at a nominally constant linear velocity, a readback head assembly configured to transduce the optically detectable patterns and readback recovery circuitry configured to obtain frequency lock on a frequency of the optically detectable patterns, the disc comprising:

a data placement zone to which first data are written to produce a first data rate as a frequency at which the first data pass the readback head assembly as the disc is rotated at a selected linear velocity;

a velocity disruption zone adjacent the data placement zone to which second data are written to produce a second data rate as a frequency at which the second data pass the readback head assembly as the head is rotated at the selected linear velocity, wherein the second data rate is different from the first data rate; and

a data rate profile zone to which information is stored in relation to variation between the first and second data rates to facilitate authentication of the disc by the readback system.

7. The optical disc of claim 6, wherein the data rate profile zone includes a target linear velocity of the disc sufficient to enable the recovery circuitry to obtain frequency lock on the second data, wherein the data rate profile zone facilitates operation of the readback system to authenticate the disc by measuring the disc linear velocity as the second data are accessed, comparing the measured disc linear velocity with the target linear velocity, and denying further disc access when a mismatch is detected between the measured and target disc linear velocities.

8. The optical disc of claim 6, wherein forensic tracking information is stored on the disc in relation to the first and second data rates.

9. A method for writing data to an optical disc in the form of optically detectable patterns for subsequent access by a disc readback system having a motor configured to rotate the disc at a nominally constant linear velocity, a readback head assembly configured to transduce the optically detectable patterns and readback recovery circuitry configured to obtain frequency lock on a frequency of the optically detectable patterns, the method comprising steps of:

(a) providing input data to be written to the disc;

(b) modulating the input data to provide a data modulation signal at a nominal frequency;

(c) selecting a data rate profile in relation to desired variation in frequencies at which different portions of the input data are to appear on the disc; and

(d) using the data modulation signal to write the input data to the disc while varying at least a selected one of the nominal frequency of the data modulation signal and a linear velocity of the disc in relation to the selected data rate profile to prevent unauthorized duplication of the disc.

10. The method of claim 9, wherein the input data comprise a first portion of data and a second portion of data, and wherein step (d) comprises steps of:

(d1) writing the first portion of data to a data placement zone to produce a first data rate as a frequency at which the first data pass the readback head assembly as the disc is rotated at a selected disc linear velocity; and

(d2) writing the second portion of data to a velocity disruption zone adjacent the data placement zone to which second data are written to produce a second data rate as a frequency at which the second data pass the readback head assembly as the head is rotated at the selected linear velocity, wherein the second data rate is different from the first data rate.

11. The method of claim 9, wherein the variation in frequencies between the first and second data rates is selected to cause the recovery circuitry, having obtained frequency lock on the first data as the first data are retrieved, to subsequently lose said frequency lock on the second data as the readback system attempts to sequentially read the first and second data during a continuous access operation.

12. The method of claim 9, further comprising a step of:

(e) writing information in relation to the selected data rate profile to a data rate profile zone on the disc, said information including a target linear velocity of the disc sufficient to enable the recovery circuitry to obtain frequency lock on the second portion of data stored in the velocity disruption zone.

13. The method of claim 12, in combination with a method for subsequently accessing the data written to the disc comprising steps of:

(f) placing the disc in the readback system;

(g) retrieving the information from the data rate profile zone;

(h) moving the readback head assembly to a location adjacent the velocity disruption zone;

(i) adjusting the disc linear velocity to a final linear velocity value sufficient to enable the recovery circuitry to obtain frequency lock on the second portion of data in the velocity disruption zone;

(j) granting access to remaining portions of the disc when the final linear velocity value is within a selected threshold value associated with the target linear velocity; and

(k) denying access to remaining portions of the disc when the final linear velocity value is beyond the selected threshold value associated with the target linear velocity.

14. A system for writing data to an optical disc in the form of optically detectable patterns, comprising:

a write assembly adjacent the disc;

a motor configured to rotate the disc at a selected linear velocity;

an encoder which modulates input data to form a data modulation signal at a nominal modulation frequency; and

a control circuit, coupled to the motor and the encoder, which variably adjusts at least a selected one of the disc linear velocity and the modulation frequency in accordance with a data rate profile to write the input data to the disc, wherein the data rate profile is selected in relation to desired variation in frequencies at which different portions of the input data are to appear on the disc to authenticate the disc as an authorized copy.

15. The system of claim 14, wherein the variation in frequencies of the data rate profile prevent continuous reading of the disc.

16. The system of claim 14, wherein the input data comprise a first portion of data and a second portion of data, wherein the control circuit operates to direct the writing of the first portion of data to a data placement zone to produce a first data rate as a frequency at which the first data pass the readback head assembly as the disc is rotated at a selected disc linear velocity, wherein the control circuit further operates to direct the writing of the second portion of data to a velocity disruption zone adjacent the data placement zone to which second data are written to produce a second data rate as a frequency at which the second data pass the readback head assembly as the head is rotated at the selected linear velocity, wherein the second data rate is different from the first data rate.

17. The system of claim 14, wherein the variation in frequencies between the first and second data rates is selected to cause a readback system, having obtained frequency lock on the first data as the first data are retrieved, to subsequently lose said frequency lock on the second data as the readback system attempts to sequentially read the first and second data during a continuous access operation.

18. The system of claim 14, wherein the control circuit further operates to write information in relation to the selected data rate profile to a data rate profile zone on the disc, said information including a target linear velocity of the disc sufficient to enable a readback system to obtain frequency lock on the second portion of data stored in the velocity disruption zone.

19. The system of claim 18, wherein the data rate profile zone facilitates detection of an unauthorized duplicate copy of the disc by the readback system by reading the second portion of data, measuring the disc linear velocity, comparing the disc linear velocity to the target linear velocity, and denying further disc access when a mismatch is detected between the measured disc linear velocity and the target linear velocity.