Information recording method, information reading method, and optical disc device

Patent metadata

Field	Value
Publication number	US-8958277-B2
Application number	US-201113286243-A
Country	US
Kind code	B2
Filing date	Nov 1, 2011
Priority date	Nov 25, 2010
Publication date	Feb 17, 2015
Grant date	Feb 17, 2015

Abstract

An optical disc device and information recording/reading method for an optical disc in which a recording layer is formed through volume recording by aligning recording tracks, which hold information, in a homogenous recording region that does not internally have a layer defining a recording position. The information recording method includes a step in which a first recording layer forming a complex recording layer is formed by forming a recording track while recording information by focusing a main beam at a predetermined depth position in the recording region, and a step in which a second recording layer forming the complex recording layer is formed by forming a recording track while recording information by focusing the main beam at a depth position that is separated from the first recording layer in a depth direction by a depth offset greater than ⅙ of a wavelength of the main beam.

First claim

What is claimed is:

1. An information recording method for forming a recording layer in an optical disc, through volume recording by aligning recording tracks, which hold information in a homogenous recording region that does not internally have a layer defining a recording position, the information recording method comprising:
forming a first recording layer forming a complex recording layer, by forming a recording track while recording information, by focusing a main beam at a predetermined depth position in the recording region; and
forming a second recording layer forming the complex recording layer, by forming a recording track while recording information, by focusing the main beam at a depth position separated from the first recording layer in a depth direction by a depth offset greater than one-sixth (⅙) of a wavelength of the main beam;
wherein a focal position of the main beam is controlled by using a first focus error signal;
wherein the first focus error signal is detected from a guide beam reflected from a reference layer the guide beam being focused on the reference layer, and the guide beam having a wavelength that differs from the wavelength of the main beam; and
wherein an effective track pitch of the complex recording layer is one-half (½) of a track pitch of the first or second recording layer.

2. An information recording method for forming a recording layer in an optical disc, through volume recording by aligning recording tracks, which hold information, in a homogenous recording region that does not internally have a layer defining a recording position, the information recording method comprising:
forming a first recording layer forming a complex recording layer, by forming a recording track while recording information, by focusing a main beam at a predetermined depth position in the recording region;
forming a second recording layer forming the complex recording layer, by forming a recording track while recording information, by focusing the main beam at a depth position separated from the first recording layer in a depth direction by a depth offset greater than one-sixth (⅙) of a wavelength of the main beam; and
forming another complex recording layer with an interlayer spacing greater than the depth offset with respect to the complex recording layer;
wherein a focal position of the main beam is controlled by using a first focus error signal;
wherein the first focus error signal is detected from a guide beam reflected from a reference layer, the guide beam being focused on the reference layer, and the guide beam having a wavelength that differs from the wavelength of the main beam; and
wherein the depth offset is less than one-quarter (¼) of a spacing between two complex recording layers that are adjacent in the depth direction.

3. An information recording method for forming a recording layer in an optical disc, through volume recording by aligning recording tracks, which hold information, in a homogenous recording region that does not internally have a layer defining a recording position, the information recording method comprising:
forming a first recording layer forming a complex recording layer, by forming a recording track while recording information, by focusing a main beam at a predetermined depth position in the recording region; and
forming a second recording layer forming the complex recording layer, by forming a recording track while recording information, by focusing the main beam at a depth position separated from the first recording layer in a depth direction by a depth offset greater than one-sixth (⅙) of a wavelength of the main beam;
wherein a focal position of the main beam is controlled by using a first focus error signal;
wherein the first focus error signal is detected from a guide beam reflected from a reference layer, the guide beam being focused on the reference layer, and the guide beam having a wavelength that differs from the wavelength of the main beam; and
wherein the optical disc includes a reference layer including a groove, the information recording method further comprising:
focusing the main beam at a region in the complex recording layer where only the first recording layer is formed, and detecting a second focus error signal from the main beam reflected from the complex recording layer;
adjusting the focal position of the main beam to a first adjustment value, so that a value of the second focus error signal is at a local minimum;
focusing the main beam at a region in the complex recording layer where both the first recording layer and the second recording layer are formed, and detecting a third focus error signal from the main beam reflected from the complex recording layer;
adjusting the focal position of the main beam to a second adjustment value, so that a value of the third focus error signal is at a local minimum;
calculating an adjustment value for focusing the main beam at the second recording layer from the first adjustment value and the second adjustment value; and
forming a recording track while postscript recording information with the main beam at a depth position of the second recording layer, by setting the focal position of the main beam at the calculated adjustment value.

4. An information recording method for forming a recording layer in an optical disc, through volume recording by aligning recording tracks, which hold information, in a homogenous recording region that does not internally have a layer defining a recording position, the information recording method comprising:
forming a first recording layer forming a complex recording layer, by forming a recording track while recording information, by focusing a main beam at a predetermined depth position in the recording region;
forming a second recording layer forming the complex recording layer, by forming a recording track while recording information, by focusing the main beam at a depth position separated from the first recording layer in a depth direction by a depth offset greater than one-sixth (⅙) of a wavelength of the main beam;
focusing the main beam by an objective lens and at a region in the complex recording layer where only the first recording layer is formed, and detecting a first focus error signal from the main beam reflected from the complex recording layer, wherein a focal position of the main beam is controlled by using the first focus error signal, and wherein the first focus error signal is detected from a guide beam reflected from a reference layer, the guide beam being focused on the reference layer, and the guide beam having a wavelength that differs from the wavelength of the main beam;
driving the objective lens so that a value of the first focus error signal is at a local minimum, and memorizing a signal for said driving as a first drive signal;
focusing the main beam at a region in the complex recording layer where both the first recording layer and the second recording layer are formed, and detecting a second focus error signal from the main beam reflected from the complex recording layer;
driving the objective lens so that a value of the second focus error signal is at a local minimum, and memorizing a signal for said driving as a second drive signal; and
determining a focus offset value based on the first drive signal and the second drive signal, wherein the focus offset value is to be applied when focusing the main beam at the first recording layer or the second recording layer at a region where both the first recording layer and the second recording layer are formed.

5. An information reading method for an optical disc in which a complex recording layer comprising a first recording layer and a second recording layer volume recording by aligning recording tracks, which hold information, at two depth positions that are separated in a dept

Assignees

• Kikugawa Atsushi
• Ide Tatsuro
• Hitachi Consumer Electronics

Inventors

• Kikugawa Atsushi
• Ide Tatsuro

Classifications

• G11B7/2405

  being also used as track layers of pre-formatted layers (tracks or pits G11B7/2407) · CPC title

• G11B7/24044

  for storing optical interference patterns, e.g. holograms; for storing data in three dimensions [3D], e.g. volume storage (G11B7/24038 takes precedence) · CPC title

• G11B7/0901 Primary

  for track following only (G11B7/0925, G11B7/094, G11B7/0941, G11B7/0943, G11B7/0945, G11B7/0946, G11B7/0948 take precedence) · CPC title