Description Of Newly Adopted Technology; Features And Format Of Dvd-Rw - Hitachi DZ-GX20MA Service Manual

Description of Operation > Description of Newly Adapted Technology
3-2 Description of Newly Adapted Technology

3-2-1 Features and Format of DVD-RW

(1) Features of DVD-RW
1) Rewriting at least 1000 times is possible.
2) The recording mode (VF mode conforming to DVD video format or VR mode conforming to DVD
video recording format) can be selected.
(2) Format of DVD-RW
DVD-RW (DVD-ReWritable) is a DVD format that adds a rewritable function to DVD-R: The format
is certified by the DVD Forum.
The format of DVD-RW attaches a high value to compatibility of playback on DVD recorders/
players, DVD-ROM drives, etc. in the same way as with DVD-R: Here it is the same as that of one-
layer DVD-ROM and DVD-R, except for the reflectance ratio.
Information:
From the viewpoint of format, DVD-R and DVD-RW (recorded in the DVD video format) will be
equivalent once they are finalized. However, since the reflectance ratio is different, a device that
can play the DVD-R may not be able to play DVD-RW.
Item
Disc diameter 12cm
Storage capacity 4.7GB/side
Thickness of disc 1.2mm
Rewritable number At least 1000
of times
Reflectance ratio 18% - 30%
Track width 0.74um
Recording/playback 635nm/650nm
laser wavelength
Table3-2-1 Comparison of DVD disc
DVD-RW
8cm 12cm
1.46GB/side 4.7GB/side
Impossible (only additional
writing is possible)
45% - 85%
3 - 3
1-layer
DVD-R
DVD-ROM
8cm 12cm
1.46GB/side 4.7GB/side
Impossible
: Same as on left
2-layer
DVD-ROM
12cm
4.25GB/layer
18% - 30%