XR-D400SL
1-4
The XR-D400 incorporates the SCMS (Serial Copy Management System) and the RID (Recorder Unique Identifier)
functions.
SCMS is used to limit digital copies to one generation only. The principles are shown in Fig. 3.
With RID, the RID codes are written into discs which are as specified in the Orange Book Parts II and III. The
codes contain the manufacturer's name, product name and machine number to enable the tracing of illegal copies.
Digital recording
Digital recording
[Fig. 3] Principles of SCMS
Fig. 4 shows the structure of a CD-R disc.
In recording, a laser beam having the same wavelength as the
CD beam (780 nm) but of tens times higher power is irradiated
from the substrate surface to the groove.
This irradiation causes thermal deformation of the organic
pigment layer forming pits in it.
The organic pigments include cyanine, phtalocyanine and azoic
dyes and the reflective layer uses gold or silver materials.
In playback the laser beam reads the pits recorded in the
pregroove.
The thermal deformation of the organic pigment layer cannot be
recovered to the original condition. As a result, the CD-R discs
cannot be rewritten and only additional writing is possible with
them.
Fig. 5 shows the structure of a CD-RW disc.
The CD-RW uses a phase-changing recording material in the
recording layer.
With the CD-RW, a laser beam with regulated power and
cooling time is irradiated to form a crystalline phase (erased
s t a t u s ) a n d a m o r p h o u s p h a s e ( r e c o r d e d s t a t e ) o n t h e
polygroove and data is reproduced according to the difference in
reflectivity of the two phases.
An amorphous state can be obtained by quick cooling after
irradiation by a strong laser beam.
The phase-changing recording material is made of a compound
of silver, indium, antimony and tellurium, and rewriting is
possible up to about 1000 times.
As the reflectivity at 780 nm of the CD-RW is lower than the CD-
R, the RF amp gain should be changed in order to play a CD-
RW disc.
SCMS and RID functions
Recording on CD-R discs
Recording on a CD-RW disc
Comparison between the CD-R and the CD-RW
Label printed surface
Protective layer groove
Reflective layer
Organic pigment layer
Substrate
pregroove
Track pitch
1.6
µ
m
Laser beam
Signal surface
[Fig. 4]
Printed surface
Protective layer
Aluminum reflective layer
Upper protective layer
Recording layer
Lower protective layer
Substrate
polygroove
Signal surface
Laser beam
[Fig. 5]
CD-R
Compact Disc Recordable
CD-RW
Compact Disc Rewritable
Specifications
Laser reflectivity
Recording power
Playback on CD player
Orange Book Part II
65% or more
4 to 11 mW
Possible
Orange Book Part III
15% to 25%
8 to 14 mW
Impossible
[Table 2]
