Optical information recording medium having first and second pit row of identical reflectance

Patent metadata

Field	Value
Publication number	US-9412408-B2
Application number	US-201414895241-A
Country	US
Kind code	B2
Filing date	Apr 8, 2014
Priority date	Jun 7, 2013
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

In a case where (i) a reflectance calculated from a reflected light amount obtained from a longest pit (P 1 max) or a longest space (S 1 max) in a first pit row is defined as a first reflectance and (ii) a reflectance calculated from a reflected light amount obtained from a longest pit (P 2 max) or a longest space (S 2 max) in the second pit row is defined as a second reflectance, the first pit row is formed such that the first reflectance becomes substantially identical with the second reflectance.

First claim

The invention claimed is:

1. An optical information recording medium comprising:
a recording layer which includes (i) a first region in which information is recorded by a first pit row that includes a pit whose length is shorter than that of an optical system resolution limit of a reproduction device and (ii) a second region in which information is recorded by a second pit row that is made up of pits whose length is equal to or longer than that of the optical system resolution limit,
in a case where (i) a reflectance calculated from a reflected light amount obtained from a longest pit or a longest space in the first pit row is defined as a first reflectance and (ii) a reflectance calculated from a reflected light amount obtained from a longest pit or a longest space in the second pit row is defined as a second reflectance,
the first pit row being formed such that the first reflectance becomes substantially identical with the second reflectance.

2. An optical information recording medium which is to be reproduced by a reproduction device that (i) emits reproduction light having a wavelength of 405 nm and (ii) includes an objective lens having a numerical aperture of 0.85, said optical information recording medium comprising:
a recording layer which includes (i) a first region in which information is recorded by a first pit row that includes a pit whose length is shorter than 119 nm and (ii) a second region in which information is recorded by a second pit row that is made up of pits whose length is equal to or longer than 119 nm,
in a case where (i) a reflectance calculated from a reflected light amount obtained from a longest pit or a longest space in the first pit row is defined as a first reflectance and (ii) a reflectance calculated from a reflected light amount obtained from a longest pit or a longest space in the second pit row is defined as a second reflectance,
the first pit row being formed such that the first reflectance becomes substantially identical with the second reflectance.

3. The optical information recording medium as set forth in claim 1 , wherein the first pit row is formed by use of a 1-7 PP modulation recording method.

4. A method for reproducing an optical information recording medium recited in claim 3 , said method comprising the step of:
decoding, with a PR(12221)ML method, a reproduction signal waveform which has been obtained by irradiating the first region with reproduction light.

5. A reproduction device by which an optical information recording medium recited in claim 3 is reproducible, said reproduction device comprising:
a reproduction light irradiation unit for irradiating the optical information recording medium with reproduction light; and
a signal processing unit for decoding, with a PR(12221)ML method, a reproduction signal waveform which has been obtained by irradiating the first region with the reproduction light emitted by the reproduction light irradiation unit.

Assignees

• Sharp Kk
• Memory-Tech Holdings Inc

Inventors

• Naka Takayuki
• Yamada Hirohisa
• Yamamoto Masaki
• Tajima Hideharu
• Konishi Masahito

Classifications

• G11B7/24085 Primary

  Pits · CPC title

• G11B7/00745

  Sectoring or header formats within a track (formats in general G11B20/12) · CPC title

• G11B2007/0133

  Details of discrete information structures, e.g. shape or dimensions of pits, prepits · CPC title

• G11B7/24065

  Layers assisting in recording or reproduction below the optical diffraction limit, e.g. non-linear optical layers or structures (cover layers for near-field media G11B7/24059) · CPC title

• G11B7/0052

  involving reflectivity, absorption or colour changes · CPC title