Copy protected disk

• US 4,823,210 A
• Filed: 08/13/1984
• Issued: 04/18/1989
• Est. Priority Date: 08/13/1984
• Status: Expired due to Fees

• Current Assignee: Verbatim Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: Verbatim Corporation (Mitsubishi Chemical Group Corp.)
• Inventors: Bond, Charles R.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Bowler, Alyssa H.
• Application Number:
  US06/639,733
• Time in Patent Office: 1,709 Days
• Field of Search: 360/60, 360/15, 360/53, 360/132, 360/133
• US Class Current: 360/60
• 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 20/00094 involving measures which result in a restriction to authorised record carriers
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: G11B 20/00586 said format change concerning the physical format of the recording medium
• CPC Class Codes: G11B 20/0071 involving a purchase action
• CPC Class Codes: G11B 20/00746 wherein the usage restriction can be expressed as a specific number
• CPC Class Codes: G11B 20/00818 wherein the usage restriction limits the signal quality, e.g. by low-pass filtering of audio signals or by reducing the resolution of video signals

Abstract

A copy protected magnetic storage disk includes a plurality of record tracks suitable for recording information-bearing data accompanied by a clock signal having a signal strength corresponding to the signal strength of the data. At least one of the record tracks includes a recording pattern representative of a code burst derived by temporarily changing the clock signal during a recording operation. Upon playback, the recording pattern of the code burst causes a random series of playback data to be produced which are dissimilar from one playback operation to the next playback operation. To verify the status of a disk (original or a copy), the code burst is read twice. With an original disk, the playback data is dissimilar; each time a copy is read, however, the same playback data is produced.

Claims

1. In a copy protected magnetic storage disk having a magnetic recording layer including a plurality of record tracks suitable for recording information-bearing data accompanied by a clock signal comprising a sequence of uniformly spaced pulses having a signal strength comparable to the signal strength of the information-bearing data, the clock signal being represented on a magnetic recording layer of a magnetic disk by a series of transitions that occur at the frequency of the clock signal pulses, the improvement comprising:

(a) at least one of the record tracks including a control pattern of magnetic transitions, recorded at a predetermined location on the recording layer of the disk, representative of a code burst derived by temporarily changing the frequency of the pulses of the clock signal during a recording operation, the frequency of the transitions of the control pattern being beyond the frequency capability of an associated playback device, to cause, in response to the playing back of the control pattern, random playback data to be produced which are dissimilar from one playback operation to the next playback operation;

(b) the recording layer including a plurality of radially arrayed sectors wherein the code burst follows a data sync gap in a predetermined recording track of one of said sectors; and

(c) a serial number is encoded about the predetermined recording track following the code burst.

2. In a copy protected magnetic storage disk having a magnetic recording layer including a plurality of record track suitable for recording information-bearing data accompanied by a clock signal comprising a sequence of uniformly spaced pulses having a signal strength comparable to the signal strength of the information-bearing data, the clock signal being represented on a magnetic recording layer of a magnetic disk by a series of transitions that occur at the frequency of the clock pulses, the improvement comprising:

(a) a plurality of control patterns of magnetic transitions, located at different but predetermined portions of at least one of the record tracks, each of the control patterns being representative of a code burst derived by temporarily changing the frequency of the pulses of the clock signal during a recording operation, the frequency of the transitions of each control pattern being beyond the frequency capability of an associated playback device to cause, in response to the playing back of each control pattern, random playback data to be produced which are dissimilar from one playback operation to the next playback operation;

(b) the information-bearing data including a software program designed to sense the presence of each of the bursts by the random data generated therefrom, the software program further being designed to have one burst erased each time the program is run, whereby the bursts act as tickets allowing the program to run only a preselected number of times.

3. In a copy protected master disk having a magnetic recording layer including a plurality of record tracks suitable for recording information-bearing data accompanied by a standard clock signal comprised of a series of predetermined pulses having a signal strength comparable to the signal strength of the information-bearing data, the clock signal being represented on a recording layer of a magnetic disk by a series of transitions that occur at the frequency of the clock pulses, the improvement comprising:

at least one of the record tracks including a control pattern of magnetic transitions, recorded at a predetermined location on the recording layer of the disk, representative of a code burst derived by temporarily changing the frequency of the standard clock signal during a recording operation, the frequency of the transitions of the control pattern causing, upon playback of said master disk, random playback data to be produced which are dissimilar from one playback operation to the next playback operation.

4. The master disk of claim 3 wherein,

said recording layer is a flexible disk.

5. In a copy protected master disk having a magnetic recording layer including a plurality of record tracks suitable for recording information-bearing data accompanied by a signal comprising a train of uniformly spaced clock pulses having a signal strength comparable to the signal strength of the information-bearing data, the clock signal being represented on a magnetic recording layer of a magnetic disk by a series of transitions that occur at the frequency of the clock pulses, the improvement comprising:

at least one of the record tracks comprising a recorded control pattern of relatively constant amplitude, at a predetermined location on the recording layer of the disk, representative of code burst derived by temporarily overriding a number of the clock pulses by producing a single, relatively long duration signal of substantially constant amplitude during a recording operation, the control pattern having an effective frequency characteristic that is less than the frequency response of an associated playback device, to cause random playback data to be produced which are dissimilar from one playback operation to the next playback operation.

6. In a copy protected master disk having a magnetic recording layer including a plurality of record tracks suitable for recording information-bearing data accompanied by a standard block signal comprising a sequence of uniformly spaced pulses having a signal strength comparable to the signal strength of the information-bearing data, the clock signal being represented on a magnetic recording layer of a magnetic disk by a series of transitions that occur at the frequency of the clock pulses, the improvement comprising:

at least one of the record tracks including a control pattern of magnetic transitions, recorded at a predetermined location on the recording layer of the disk, representative of a code burst derived by temporarily increasing the frequency of the pulses of the standard clock signal, the frequency of the transitions of the control pattern being greater than the frequency response of an associated playback device, to cause random magnetic playback impulses to be produced which are dissimilar from one playback operation to the next playback operation.

7. A method for producing a copy protected master disk having a magnetic recording layer including a plurality of record tracks having information-bearing data accompanied by a clock signal comprising a sequence of predetermined pulses having a signal strength comparable to the signal strength of the information-bearing data, the clock signal being represented on a magnetic recording layer of a magnetic disk by a series of transitions that occur at the frequency of the clock pulses, said method comprising:

recording in a predetermined location on at least one of the record tracks a control pattern of magnetic transitions representative of a code burst derived by temporarily altering the frequency of the pulses of the clock signal, the frequency of the transitions of the control pattern being outside the frequency response of an associated playback device, to produce random playback data which are dissimilar from one playback operation to the next playback operation.