Optical recording medium having a non-volatile identification code and method for encoding data using same

• US 5,661,703 A
• Filed: 03/21/1996
• Issued: 08/26/1997
• Est. Priority Date: 06/27/1995
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Fujitsu Limited
• Inventors: Moribe, Mineo, Izumi, Haruhiko, Taguchi, Masakazu, Tsugawa, Iwao
• Primary Examiner(s): DINH, TAN X
• Application Number:
  US08/620,083
• Time in Patent Office: 523 Days
• Field of Search: 369/14, 369/275.1, 369/47, 369/48, 369/54, 369/58, 235/454, 235/487, 235/468
• US Class Current: 369/14
• CPC Class Codes: G11B 11/10582 Record carriers characterised by the selection of the material or by the structure or form
• CPC Class Codes: G11B 19/02 Control of operating function, e.g. switching from recording to reproducing
• 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 20/00876 wherein physical copy protection means are attached to the medium, e.g. holograms, sensors, or additional semiconductor circuitry
• CPC Class Codes: G11B 23/281 by changing the physical properties of the record carrier
• CPC Class Codes: G11B 23/284 on the record carrier
• CPC Class Codes: G11B 23/36 Signals on record carriers or on containers and recorded by the same method as the main recording
• CPC Class Codes: G11B 7/24 Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the arrangement of information on the carrier G11B7/007
• CPC Class Codes: G11B 7/24085 Pits
• CPC Class Codes: G11B 7/26 Apparatus or processes specially adapted for the manufacture of record carriers

Abstract

An optical recording medium in which a medium identification code is recorded by using a nonvolatile mark which is formed through irreversible change of a recording film, such as magnetization characteristic change, deformation and formation of a hole, so as to prevent illegal copy of the optical recording medium, and a recording/reproducing method for the same.

Claims

1. A magneto-optical recording medium, comprising:

a substrate having plural tracks and having a groove separating individual said tracks;

a recording film formed on said substrate for recording data, and having a magnetization direction corresponding to data to be recorded, the data being recorded on the recording film through application of an external magnetic field and light beam irradiation which is moved relatively with the recording film; and

a non-volatile mark recorded on said recording film by irreversibly changing a magnetic characteristic of the recording film under application of an external magnetic field in a direction of erasing the recording mark by at least one of moving the optical recording medium at a velocity lower than that used for forming the recording mark thus irradiating a portion of said recording film for a longer duration, and irradiating the optical recording medium with a light beam stronger than that used for forming the recording mark.

2. The magneto-optical recording medium according to claim 1, wherein said nonvolatile mark is a medium identification code.

3. The optical recording medium according to claim 1, wherein one nonvolatile mark is formed in each of an odd number of adjacent track areas.

4. The optical recording medium according to claim 1, wherein one nonvolatile mark is formed in one track area and each of two groove areas sandwiching the track area.

30. The magneto-optical recording medium according to claim 1 wherein said non-volatile mark is a medium identification code which is unique for each recording medium.

5. A magneto-optical recording medium, comprising:

a substrate;

a recording film formed on the substrate having plural tracks for storing user data and further having a track gap interposed between each of said plural tracks, and

a medium identification code recorded on the recording film as a nonvolatile mark formed by irreversibly changing a portion of the recording film.

6. The optical recording medium according to claim 5, wherein said medium identification code is recorded in each of plural portions of said recording film.

7. The optical recording medium according to claim 5, wherein one medium identification code is formed in each of an odd number of adjacent said track areas.

8. The optical recording medium according to claim 5, wherein one medium identification code is recorded in one said track area and each of two said groove areas sandwiching said track area.

31. The magneto-optical recording medium according to claim 5 wherein said medium identification code is unique for each recording medium.

9. A magneto-optical recording medium, comprising:

a substrate;

a recording film formed on the substrate, for recording data;

wherein on the recording film are recorded;

a medium identification code recorded as a nonvolatile mark formed by irreversibly changing a portion of the recording film; and

a recording program for encoding data based on the reproduced medium identification code.

10. A magneto-optical recording medium, comprising:

a substrate; and

a recording film formed on the substrate, for recording data;

wherein on the recording film are recorded;

a medium identification code as a nonvolatile mark formed by irreversibly changing a portion of the recording film; and

a reproducing program for decoding reproduced data based on said medium identification code.

32. The magneto-optical recording medium according to claim 10 wherein said medium identification code is unique for each recording medium.

11. An optical recording medium, comprising:

a substrate;

a recording film formed on the substrate, for recording data;

wherein on the recording film are recorded;

a medium identification code recorded as a nonvolatile mark formed by irreversibly changing a portion of the recording film;

a recording program for encoding data based on the reproduced medium identification code; and

a reproducing program for decoding data based on the medium identification code.

33. The magneto-optical recording medium according to claim 11 wherein said medium identification code is unique for each recording medium.

12. An optical recording medium, comprising:

a substrate; and

a recording film formed on the substrate, for recording data,

wherein on the recording film are recorded;

a medium identification code as a nonvolatile mark formed by irreversibly changing a portion of the recording film; and

data, encoded using said medium identification code.

13. The optical recording medium according to claim 12, wherein the encoded data is recorded as a read-only data.

14. The optical recording medium according to claim 12, wherein the encoded data is recorded as a rewritable data.

15. An optical recording medium, comprising:

a substrate; and

a recording film formed on the substrate, for recording data,

wherein on the recording film, a medium identification code is recorded as a nonvolatile mark by irreversibly changing a magnetization characteristic of the recording film.

16. An optical recording medium, comprising:

a substrate; and

a recording film formed on the substrate, for recording data,

wherein on the recording film, a medium identification code is recorded as a nonvolatile mark formed through irreversible change of a portion of the recording film, by at least one of moving the optical recording medium at a velocity lower than that used for forming the recording mark, and irradiating the optical recording medium with a light beam stronger than that used for forming the recording mark.

17. The optical recording medium according to claim 16, wherein said irreversible change is deformation of the recording film.

18. The optical recording medium according to claim 16, wherein said irreversible change is formation of a hole in said recording film.

19. A recording method for a magneto-optical recording medium including a recording film, for storing data comprising the steps of:

applying an external magnetic field in a direction for erasing the data to the recording film; and

forming a nonvolatile mark by irreversibly changing a magnetization characteristic of the recording film by at least one of moving the optical recording medium at a velocity lower than that used for forming the recording mark, and irradiating the optical recording medium with a light beam stronger than that used for forming the recording mark.

20. A reproducing method for a magneto-optical recording medium in which a nonvolatile mark is formed in a recording film, said method comprising the steps of:

irradiating an area of the recording film where the nonvolatile mark is formed with a light beam; and

detecting light reflected by the recording film so as to reproduce a data recorded by using the nonvolatile mark from a magneto-optical reproducing waveform output,

wherein the nonvolatile mark is formed by irreversibly changing a magnetization characteristic of the recording film under application of an external magnetic field in a direction for erasing the recording mark by at least one of moving the optical recording medium at a velocity lower than that used for forming the recording mark, and irradiating the optical recording medium with a light beam stronger than that used for forming the recording mark.

21. A reproducing method for a magneto-optical recording medium in which a nonvolatile mark is formed in a recording film, comprising the steps of:

detecting one nonvolatile mark being formed in each of an odd number of adjacent track areas on the recording film; and

reproducing the nonvolatile mark recorded in the center track area,

wherein the nonvolatile mark is formed by irreversibly changing a magnetization characteristic of the recording film under application of an external magnetic field in a direction for erasing the recording mark by at least one of moving the optical recording medium at a velocity lower than that used for forming the recording mark, and irradiating the optical recording medium with a light beam stronger than that used for forming the recording mark.

22. A reproducing method for a magneto-optical recording medium in which a nonvolatile mark is formed in a recording film, comprising the steps of:

detecting one nonvolatile mark being formed in one track area and two groove areas sandwiching the track area on the recording film; and

reproducing the nonvolatile mark formed in the track area sandwiched between the groove areas,

wherein the nonvolatile mark is formed by irreversibly changing a magnetization characteristic of the recording film under application of an external magnetic field in a direction for erasing the recording mark by at least one of moving the optical recording medium at a velocity lower than that used for forming the recording mark, and irradiating the optical recording medium with a light beam stronger than that used for forming the recording mark.

23. A reproducing method for an optical recording medium in which a nonvolatile mark is formed in a recording film by irreversibly changing a portion of the recording film, said method comprising the steps of:

reproducing a plurality of identical medium identification codes each recorded by using the nonvolatile mark, without conducting error correction generally performed in a reproducing operation, so as to obtain a plurality of reproducing codes; and

conducting a majority operation on the reproducing codes, so as to select one of the reproducing codes as a correct medium identification code.

24. A reproducing method for an optical recording medium in which a nonvolatile mark is formed in a recording film by irreversibly changing a portion of the recording film, comprising the steps of:

reproducing a plurality of identical medium identification codes each recorded by using the nonvolatile mark excluding at least one predetermined medium identification code; and

reproducing the predetermined medium identification code when the remaining medium identification codes are unreproducible.

25. A reproducing method for an optical recording medium in which a nonvolatile mark is formed in a recording film by irreversibly changing a portion of the recording film, comprising the steps of:

detecting a plurality of identical medium identification codes, each recorded by using the nonvolatile mark, being recorded in each of an odd number of adjacent track areas on the recording film; and

reproducing the medium identification code recorded in the center track area.

26. A reproducing method for an optical recording medium in which a nonvolatile mark is formed in a recording film by irreversibly changing a portion of the recording film, comprising the steps of:

detecting a plurality of identical medium identification codes, each recorded by using the nonvolatile mark, being formed in one track area and two groove areas sandwiching the track area on the recording film; and

reproducing the medium identification code formed in the track area sandwiched between the groove areas.

27. A recording method for an optical recording medium in which a nonvolatile mark is formed on a recording film by irreversibly changing a portion of the recording film, comprising the steps of:

reproducing a medium identification code recorded by using the nonvolatile mark;

encoding data based on the reproduced medium identification code; and

recording the encoded data.

28. A reproducing method for an optical recording medium in which a nonvolatile mark is formed on a recording film by irreversibly changing a portion of the recording film, comprising the steps of:

conducting an erasing operation for a recording mark on a recording area where a medium identification code is recorded by using the nonvolatile mark;

reproducing the medium identification code after the erasing operation;

reproducing recorded data; and

decoding the reproduced data based on the reproduced medium identification code.

29. A recording/reproducing method for an optical recording medium in which a nonvolatile mark is formed on a recording film by irreversibly changing a portion of the recording film, comprising the steps of:

reproducing a medium identification code recorded by using the nonvolatile mark;

encoding data based on the reproduced medium identification code;

recording the encoded data;

conducting an erasing operation for a recording mark on a recording area where the medium identification code is recorded by using the nonvolatile mark;

reproducing the medium identification code after the erasing operation;

reproducing the encoded data; and

decoding the reproduced data based on the reproduced medium identification code.