a new technology that attempts addressing the problem of writing reliably writing
to the most CD-R media that is sold in the massive market.
The explosion in demand for CD Recordable (CD-R) discs and the
endless race of higher recording speed and lower cost has led to the production
and sale of a great many makes and types of discs, both branded and unbranded.
Numerous manufacturers all over the world are producing high volumes of CD-R
media that sometimes have questionable quality. Thermo-Balanced Writing attempts
to solve that problem.
- What "Quality" means for the CD-R media?
The non compliance of CD-R media with the global standards set
out in the Orange Book for CD-R media. The original concept of design the Compact
Disc audio and data drives and their various media types and applications was
to have the maximum compatibility, including backwards compatibility, wherever
possible. For that propose, standards have been agreed between major CD manufacturers.
However real life shows that some CD-R discs available in the
market do not match up in the basic technical parameters of the standards established
in the Orange Book. The production facilities and the quality control may be
in not the desired levels, the materials which are used are not the proper one.
There can be patches of the disc surface almost without recording medium (in
addition to scratches, dirty marks or other surface defects), or gross mechanical
damage which results in imbalance and reading problems after the writing of
- How CD-R media is produced?
The recording process used for CD-R discs relies on the heating
effect of a laser pulse focussed on the dye layer of the disc. Where the laser
pulse is applied, a "pit" is created and the reflectivity of the surface
is reduced. The signal representing the (digital) data is recorded in the succession
of these pits, separated by reflective "lands" of unburned material.
The current recording system (drive + disc) is very sensitive to variations
outside the Orange Book specifications, particularly when writing at high speeds
(12x and higher). Each manufacturer in order to achieve ultra high recording
speeds have followed its own way since there is not Orange Book specification
for recording higher than 16x.
- What potiential problems could occur?
The heat produced by the laser pulse should be just enough to
burn a pit to the right size and density. However, if the dye layer is of poor
quality, or the disc manufacture is defective, the right amount of cooling may
not occur in the medium between successive pulses. This results in dimensions
of individual pits which can be too large and the possibility of errors may
occur in reading ( "cross-talk" between tracks).
Profile during CD-R write phase
Also, if the pits come out too small or too light, then other reading errors
can occur. If a CD-R drive has no technology of controlling the burn process,
to check the nature of the media, then the use of low quality media will cause
defective recordings and ,most possibly, readability problems.
- How Philips promises to overpass it?
Philips has developed a system of self-calibration for recording CD-R discs.
This solution is "on board" in the drive itself. It is called TBW
[Thermo-Balanced Writing]. TBW, partnering with a Self-Learning process, adds
intelligence to the drive and enables it to automatically make decisions about
how to process and write a new disc. TBW technology is not applicable to the
RW disc since the re-writing function done with a completely different recording
The 2 major points of the Philips solution is: a) new hardware
and b) firmware built into the drive with the TBW algorithm which evaluates
the disc and determines the burn parameters.
- How the TBW algorithm works?
When a blank disc is inserted, the drive starts the self learning
algorithm for the specific media. What happens is a fast sequence of tests that
determine precisely the power dosage of the laser burn pulses that need to be
applied to the particular disc that the TBW intelligent CD-RW drive itself discovers
to have been inserted in the disc tray.
In a some seconds a sequence of physical tests are performed
on the disc to determine its characteristics. A series of test pits are burned
into the disc at the appropriate speed and with the burn laser pulsed as necessary
to achieve the optimal relationship between pits and lands, in particular, to
provide the correct reflectivity differential, the correct position, length
and spacing of each element and an acceptable block error rate. The test burn
is then read and if the result is within the Orange Book specifications, the
disc is qualified for the maximum recording speed.
If the test results are not good, then the algorithm re-does
the above testing, however this time with a lower writing speed (example 8x).
If the media behaves well with that recording speed, then the drive adopts that
speed and proceeds in the recording process. During the burn process, TBW tailors
the laser pulses to give exactly the right amount of heat so as to create a
sequence of signal pits all having the right size and density. The result is
an optimal ratio of reflectivity between pits and lands, with the correct size
and spacing defined.
The TBW technology ensures that each media is treating differently
and that the produced disc will always be in the best possible condition. The
user will notice the higher recording time if low quality media is used. Also
the CDR software will inform them of the new recording speed.
In other words, the TBW intelligent drive can calibrate itself
and so automatically compensates for variables in the recording media; and every
disc is treated individually. This feedback system offers other advantages over
one with fixed parameters: if the laser characteristics vary over time or if
it suffers from a build-up of dirt, the effect on its output will automatically
be compensated for by the TBW feature. This makes for greater reliability, and
longer useful life of the drive itself.
According to Philips tests, most sub-specification CD-R media
can now be satisfactorily written and read with a very limited chance of rejection.
The new Philips 12x8x32x CD-RW is the first product to have been introduced
utilising TBW technology and from now, all Philips 8x4x32x CD-RW drives have