US 7,548,499 B2Granted

Offset amount measuring method and apparatus

AssigneePioneer Corporation

InventorsTakao Tagiri, Seiro Oshima

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Abstract

An offset amount measuring method is provided with: a recording process for measurement (i) of recording information for measurement, into a recording track in the L0 layer, by a predetermined section, from a measurement reference position, and of (ii) recording the information for measurement, into a recording track in the L1 layer, by the predetermined section, from or toward a measurement correspondence position, which is associated with the measurement reference position by the pre-format address; a first detecting process of detecting a border of a first recorded area in which the information for measurement is recorded and a first unrecorded area in the first recording track, on the basis of a difference in reflectance between the first recorded area and the first unrecorded area; a second detecting process of detecting a second border position in the recording track in the L1 layer, on the basis of a difference in reflectance; and a determining process of determining the offset amount, on the basis of the detected first and second border positions. Moreover, it is also provided with a judging process of judging whether or not the determined offset amount is within tolerance with respect to the first offset amount set in advance for offset countermeasures.

Claims18

Dependent claims

An offset amount measuring method of measuring an offset amount, which is a shift amount in a radial direction between radial positions on first and second recording tracks, the radial positions being associated with each other by a pre-format address given in advance to the first and second recording tracks, in an information recording medium comprising at least:

a disc-shaped first recording layer in which the first recording track is formed to record therein record information;
and a disc-shaped second recording layer in which the second recording track is formed to record therein the record information in a direction equal to or opposite to that in the first recording track of the first recording layer,
said offset amount measuring method comprising:
a recording process for measurement (i) of recording information for measurement, into the first recording track, by a predetermined section or by a predetermined length, from one measurement reference position which is specified by the pre-format address, and (ii) of recording the information for measurement, into the second recording track, by the predetermined section or by the predetermined length, from or toward a measurement correspondence position, which is associated with the one measurement reference position by the pre-format address;
a first detecting process of detecting a first border position which is a border of a first recorded area in which the information for measurement is recorded and a first unrecorded area in which the information for measurement is unrecorded in the first recording track, on the basis of a difference in reflectance between the first recorded area and the first unrecorded area, with a central axis of said information recording medium as a reference;
a second detecting process of detecting a second border position which is a border of a second recorded area in which the information for measurement is recorded and a second unrecorded area in which the information for measurement is unrecorded in the second recording track, on the basis of a difference in reflectance between the second recorded area and the second unrecorded area, with the central axis as a reference;
and
a determining process of determining the offset amount, on the basis of the detected first and second border positions.

5 more elements

An offset amount measuring apparatus for measuring an offset amount, which is a shift amount in a radial direction between radial positions on first and second recording tracks, the radial positions being associated with each other by a pre-format address given in advance to the first and second recording tracks, in an information recording medium comprising at least:

a disc-shaped first recording layer in which the first recording track is formed to record therein record information;
and a disc-shaped second recording layer in which the second recording track is formed to record therein the record information in a direction equal to or opposite to that in the first recording track of the first recording layer,
said offset amount measuring apparatus comprising:
a recording device (i) for recording information for measurement, into the first recording track, by a predetermined section or by a predetermined length, from one measurement reference position which is specified by the pre-format address, and (ii) for recording the information for measurement, into the second recording track, by the predetermined section or by the predetermined length, from or toward a measurement correspondence position, which is associated with the one measurement reference position by the pre-format address;
a first detecting device for detecting a first border position which is a border of a first recorded area in which the information for measurement is recorded and a first unrecorded area in which the information for measurement is unrecorded in the first recording track, on the basis of a difference in reflectance between the first recorded area and the first unrecorded area, with a central axis of said information recording medium as a reference;
a second detecting device for detecting a second border position which is a border of a second recorded area in which the information for measurement is recorded and a second unrecorded area in which the information for measurement is unrecorded in the second recording track, on the basis of a difference in reflectance between the second recorded area and the second unrecorded area, with the central axis as a reference;
and
a determining device for determining the offset amount, on the basis of the detected first and second border positions.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/301,245Filed 13 Dec 2005
Priority: JP 2004-36688817 Dec 2004
Published: US 2006/0133244 A122 Jun 2006
Granted: 16 Jun 2009
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

G11B 7/24038
Recording layers: multiple laminated recording layers
G11B 7/0953
Specially adapted for discs, e.g. for compensation of eccentricity or wobble: to compensate for eccentricity of the disc or disc tracks
G11B
Information storage based on relative movement between record carrier and transducer