Description Of Newly Adapted Technology; Blu-Ray Disc (Bd) - Hitachi DZ-BD7HA Service Manual

Description of Operation > Description of Newly Adapted Technology

3-2 Description of Newly Adapted Technology

(*1)
3-2-1 Blu-ray Disc (BD)
(1) Overview of BD and Specifi cations
A Blu-ray disc (BD) is an optical disc whose format has been established by the Blue-ray Disc As-
sociation (BDA): Data is written and read using blue-purple laser.
A BD achieves a shorter track pitch by using a blue-purple laser with shorter wavelength and en-
hancing the NA value
times that of same-size DVD (single-sided, one layer).
Table 3-2-1 Comparison of Specifi cations between BD and DVD
Item
Disc diameter
Storage capacity (GB)
Laser wavelength (nm)
(*2)
Lens NA value
Track pitch (μm)
Thickness of disc (mm)
Thickness of light transmission
protective layer (mm)
*1: The logo "Blu-ray Disc" has no "e" following "Blu".
*2: NA stands for numerical aperture, which is a value that shows how a lens focuses light.
The higher the NA value, the shorter the focal distance will be, so the thickness of light transmission
protective layer can be as small as 0.1 mm.
*3: The storage capacity on BD varies depending on the format and version. See Table 3-3-2 for details.
(2) Physical formats of discs
Format Overview
BD-RE Rewritable up to 10,000
times
BD-R Recordable only once
BD-ROM Playback (read) only
*4: BD-FS stands for Blu-ray disc fi le system: This recording format will improve the playback response.
The BD-FS format divides the disc recording area between "real-time data area" - where the stream of
video/audio, etc. is recorded - and the "gathered fi le area" - where the stream control database is
recorded, which improves the response.
(*2)
, as shown in the table below, enabling the storage capacity more than fi ve
BD (single-sided, 1 layer)
12cm
(*3)
25
Table 3-2-2 List of Physical Formats of Discs
Ver. 1.0
Ver. 2.1
Ver. 1.1
Ver. 1.0
DVD (single-sided, 1 layer)
8cm
7.5
405
0.85
0.32
1.2
0.1
Major version and characteristics
Disc in cartridge
(*4)
File format: BD-FS
Storage capacity: 23.3 GB (12 cm, single-sided, 1 layer)
Bare disc
File format: UDF2.5
Storage capacity: 25 GB (12 cm, single-sided, 1 layer)
Bare disc
File format: UDF2.6
Storage capacity: 25 GB (12 cm, single-sided, 1 layer)
Bare disc
File format: UDF2.5
Storage capacity: 25 GB (12 cm, single-sided, 1 layer)
3 - 3
12cm 8cm
4.7 1.46
650
0.6
0.74
1.2
0.6