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

Patent metadata

Field	Value
Publication number	US-9978415-B2
Application number	US-201715678240-A
Country	US
Kind code	B2
Filing date	Aug 16, 2017
Priority date	Jun 7, 2013
Publication date	May 22, 2018
Grant date	May 22, 2018

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, and
the first region having a narrower track pitch than the second region.

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, and
the first region having a narrower track pitch than the second region.

Assignees

• Sharp Kk
• Memory Tech Holdings Inc

Inventors

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

Classifications

• G11B7/24085

  Pits · CPC title

• G11B7/00745

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

• G11B7/24

  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) · CPC title

• G11B7/24079

  Width or depth (G11B7/24076 takes precedence) · CPC title

• G11B7/243

  comprising inorganic materials only, e.g. ablative layers · CPC title