Magneto-optical recording medium having watermark for preventing unauthorized copy

• US 7,414,924 B2
• Filed: 03/09/2005
• Issued: 08/19/2008
• Est. Priority Date: 12/19/1996
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Oshima, Mitsuaki, Gotoh, Yoshiho, Tanaka, Shin-ichi, Koishi, Kenji, Moriya, Mitsurou, Murakami, Motoyoshi, Miyatake, Norio, Konishi, Shinichi, Takemura, Yoshinari
• Primary Examiner(s): Dinh; Tan X
• Application Number:
  US11/075,601
• Publication Number:
  US 20050163026A1
• Time in Patent Office: 1,259 Days
• Field of Search: None
• US Class Current: 369/13.35
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: G06T 2201/0064 for copy protection or copy management, e.g. CGMS, copy only once, one-time copy
• CPC Class Codes: G11B 11/10506 by modulating only the light beam of the transducer
• CPC Class Codes: G11B 11/10515 Reproducing compensating pit shift G11B11/1053
• CPC Class Codes: G11B 11/10584 characterised by the form, e.g. comprising mechanical protection elements
• CPC Class Codes: G11B 11/10595 Control of operating function
• 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 20/00123 the record carrier being identified by recognising some of its unique characteristics, e.g. a unique defect pattern serving as a physical signature of the record carrier
• CPC Class Codes: G11B 20/00166 involving measures which result in a restriction to authorised contents recorded on or reproduced from a record carrier, e.g. music or software
• CPC Class Codes: G11B 20/00181 using a content identifier, e.g. an international standard recording code [ISRC] or a digital object identifier [DOI]
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: G11B 20/00231 wherein the key is obtained from a local external medium, e.g. a card
• CPC Class Codes: G11B 20/0026 the key being stored as a barcode
• CPC Class Codes: G11B 20/00268 said barcode being recorded in a burst cutting area [BCA]
• CPC Class Codes: G11B 20/00347 wherein the medium identifier is used as a key
• 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 20/00884 involving a watermark, i.e. a barely perceptible transformation of the original data which can nevertheless be recognised by an algorithm
• CPC Class Codes: G11B 20/10 Digital recording or reproducing
• CPC Class Codes: G11B 20/1217 on discs
• CPC Class Codes: G11B 20/1258 where blocks are arranged within multiple radial zones, e.g. Zone Bit Recording or Constant Density Recording discs, MCAV discs, MCLV discs
• CPC Class Codes: G11B 2020/122 : Burst cutting area [BCA]
• CPC Class Codes: G11B 2020/1244 : CAV zone, in which a constant angular velocity is used
• CPC Class Codes: G11B 2020/1245 : CLV zone, in which a constant linear velocity is used
• CPC Class Codes: G11B 23/281 : by changing the physical properties of the record carrier
• CPC Class Codes: G11B 23/288 : Protecting disks from being written or overwritten
• CPC Class Codes: G11B 23/40 : Identifying or analogous means applied to or incorporated in the record carrier and not intended for visual display simultaneously with the playing-back of the record carrier, e.g. label, leader, photograph
• CPC Class Codes: G11B 7/0037 : with discs
• CPC Class Codes: G11B 7/0045 : Recording G11B7/006, G11B7/0065 take precedence
• CPC Class Codes: G11B 7/00736 : Auxiliary data, e.g. lead-in, lead-out, Power Calibration Area [PCA], Burst Cutting Area [BCA], control information sector headers or adresses in prepits G11B7/00745; address data in track wobble G11B7/24082
• 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

Abstract

An optical disk that includes main information and write-once information recorded on the optical disk. The write-once information is recorded as information unique to the optical disk, and the write-once information stores at least watermark production parameters for producing a watermark.

Claims

1. An optical disk comprising:

a disk substrate; and

a recording layer on the disk substrate, the recording layer being optically detectable;

wherein main information is recorded on the optical disk, and

write-once information is formed as a plurality of stripe-shaped marks that are oblong in a radial direction of the optical disk in a pre-determined portion of the recording layer, the write-once information being recorded as information unique to the optical disk, and the write-once information storing at least watermark production parameters for producing a watermark.

2. The optical disk according to claim 1, wherein the main information is recorded by providing convex-concave pits in a reflective layer, and the write-once information is recorded by partially removing the reflective layer.

3. The optical disk according to claim 1, wherein the main information and the write-once information are recorded by partially changing a reflection coefficient of the recording layer.

4. The optical disk according to claim 1, wherein the recording layer comprises a magnetic layer with a magnetic anisotropy in a direction perpendicular to a surface of the magnetic layer, the main information is recorded by partially changing a magnetization direction of the recording layer, and the write-once information is recorded by partially changing the magnetic anisotropy in the direction perpendicular to the surface of the magnetic layer.