Information recording medium, information reproduction apparatus, and information reproduction method

• US 20020159376A1
• Filed: 04/26/2002
• Published: 10/31/2002
• Est. Priority Date: 04/27/2001
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Ohsawa, Hideaki
• Granted Patent: US 6,937,550 B2
• Time in Patent Office: Days
• US Class Current: 369/111
• 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 7/24038 Multiple laminated recording layers

Abstract

An information recording medium according to an embodiment of this invention has a plurality of disk-like information recording layers, which are adhered to each other within an allowable decentering error range, and an embossed lead-in area assured on each information recording layer has first guard tracks which are formed within the range of the first radial distance from the radial position of the innermost periphery of the embossed lead-in area toward the outer periphery side, and second guard tracks which are formed within the range of the second radial distance from the radial position of the outermost periphery of the embossed lead-in area toward the inner periphery side.

Claims

1. An information recording medium comprising:

a plurality of disk-like information recording layers which are adhered to each other within an allowable decentering error range,

each of said information recording layers comprising;

an embossed lead-in area which is located at a predetermined radial position; and

a data area which neighbors said embossed lead-in area and is located on an outer periphery side of said embossed lead-in area, and on which user data is recorded by phase change recording marks,

said embossed lead-in area comprising;

first guard tracks which are formed within a range of a first radial distance from a radial position of an innermost periphery of said embossed lead-in area toward the outer periphery side;

second guard tracks which are formed within a range of a second radial distance from a radial position of an outermost periphery of said embossed lead-in area toward the inner periphery side; and

data recording tracks which are formed between said first and second guard tracks and on which lead-in data is recorded by embossed pits.

2. A medium according to claim 1, wherein if x represents the allowable decentering error,

the first and second radial distances are x, and a defect caused by the allowable decentering error is covered by said first and second guard tracks.

3. A medium according to claim 1, wherein if x represents the allowable decentering error, t represents a distance between said information recording layers, and n·

sinθ

(n;

a refractive index of an intermediate layer formed between said information recording layers) represents a numerical aperture of an objective lens used in recording/reproduction for said information recording layers,

each of the first and second radial distances is (x+t·

tanθ

), and a defect caused by the allowable decentering error is covered by said first and second guard tracks.

4. A medium according to claim 1, wherein said first and second guard tracks include embossed pits that represent physical address data and dummy data.

5. A medium according to claim 2, wherein said first and second guard tracks include embossed pits that represent physical address data and dummy data.

6. A medium according to claim 3, wherein said first and second guard tracks include embossed pits that represent physical address data and dummy data.

7. A medium according to claim 1, wherein each of said information recording layers has spiral tracks which include said first and second guard tracks and are formed from an inner periphery side toward an outer periphery side across said embossed lead-in area and said data area, and

said spiral tracks on each of said information recording layers have embossed pits which are formed at predetermined intervals in turn from the inner periphery side toward the outer periphery side, and reflect physical address data.

8. An information reproduction apparatus for reproducing information from an information recording medium, comprising:

an irradiation section configured to irradiate said information recording medium with a light beam; and

a reproduction section configured to receive the light beam reflected by data recording tracks formed between first and second guard tracks on an embossed lead-in area on said information recording medium, and reproduce lead-in data represented in the reflected light beam,

said information recording medium comprising;

a plurality of disk-like information recording layers which are adhered to each other within an allowable decentering error range,

each of said information recording layers comprising;

said embossed lead-in area which is located at a predetermined radial position; and

a data area which neighbors said embossed lead-in area and is located on an outer periphery side of said embossed lead-in area, and on which user data is recorded by phase change recording marks,

said embossed lead-in area comprising;

said first guard tracks which are formed within a range of a first radial distance from a radial position of an innermost periphery of said embossed lead-in area toward the outer periphery side;

said second guard tracks which are formed within a range of a second radial distance from a radial position of an outermost periphery of said embossed lead-in area toward the inner periphery side; and

said data recording tracks which are formed between said first and second guard tracks and on which lead-in data is recorded by embossed pits.

9. An information reproduction method of reproducing information from an information recording medium, comprising:

irradiating said information recording medium with a light beam; and

receiving the light beam reflected by data recording tracks formed between first and second guard tracks on an embossed lead-in area on said information recording medium, and reproducing lead-in data represented in the reflected light beam,

said information recording medium comprising;

a plurality of disk-like information recording layers which are adhered to each other within an allowable decentering error range,

each of said information recording layers comprising;

said embossed lead-in area which is located at a predetermined radial position; and

a data area which neighbors said embossed lead-in area and is located on an outer periphery side of said embossed lead-in area, and on which user data is recorded by phase change recording marks,

said embossed lead-in area comprising;

said first guard tracks which are formed within a range of a first radial distance from a radial position of an innermost periphery of said embossed lead-in area toward the outer periphery side;

said second guard tracks which are formed within a range of a second radial distance from a radial position of an outermost periphery of said embossed lead-in area toward the inner periphery side; and

said data recording tracks which are formed between said first and second guard tracks and on which lead-in data is recorded by embossed pits.