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

Patent metadata

Field	Value
Publication number	US-10068605-B2
Application number	US-201815944822-A
Country	US
Kind code	B2
Filing date	Apr 4, 2018
Priority date	Jun 7, 2013
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

In a case where (i) a reflectance calculated from a reflected light amount obtained from a longest pit (P1max) or a longest space (S1max) 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 (P2max) or a longest space (S2max) 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
polarity information for identifying a pit polarity being recorded in 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
polarity information for identifying a pit polarity being recorded in the second region.

3. A method for reproducing an optical information recording medium recited in claim 1 , said method comprising the step of:
carrying out tracking on a basis of the polarity information obtained by emitting reproduction light to the second region.

4. A method for reproducing an optical information recording medium recited in claim 2 , said method comprising the step of:
carrying out tracking on a basis of the polarity information obtained by emitting reproduction light to 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

• G11B7/005

  Reproducing (G11B7/0065 takes precedence) · CPC title

• G11B7/013

  for discrete information, i.e. where each information unit is stored in a distinct discrete location {, e.g. digital information formats within a data block or sector} · CPC title

• G11B7/1372

  Lenses · CPC title

• G11B7/0052

  involving reflectivity, absorption or colour changes · CPC title