Philips RWDV2010K/00, RWDV1610B/00, PCRW4012K/00, PCRW1208K/00, JR12CDRWK/05 User Manual

Thermo-Balanced Writing

Thermo-Balanced Writing

Thermo Balanced Writing

for optimal recording

Thermo-Balanced Writing

A new,patented,system addressing the problem of writing reliably to the very many brands of
recordable CD media now on the mark et,not all of which are in conformance with the agreed
international standards established for use in Philips CD-R W drives.

Introduction

The explosion in demand for CD Recordable (CD-R) discs and the relentless pursuit of ev er lower costs and
higher speeds has led to the production and sale of a great many mak es and types of discs,both branded and
unbranded.Numerous manufacturers all over the w orld are now pr oducing what has become a commodity
item.Unfortunately,in some cases,the quality of these discs are not in accordance with global standards set out
in the Orange Book for CD-R media.

The original intent underlying the development and mark eting of the expanding family of Compact Disc audio
and data drives and their various media types and applications was to hav e the maximum degree of
compatibility ,including backwards compatibility ,wherev er possible.For this reason,the series of agreed global
or international standards comprised in the Orange Book hav e been developed in co-operation and agr eement
of all major firms involved in the de velopment and exploitation of this technology .

It is this common standard and the insistence on compatibility ,which has largely been responsible for the rapid
acceptance and intensive development and gr owth of this versatile storage medium.

Unfortunately ,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. Production facilities and quality control ma y be inadequate,and
infrequently ,sub-standard materials are used or dy e la yers are insufficiently and unif ormly deposited on the
substrate.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.

The CD-R process

The recording process used f or CD-R discs relies on the heating effect of a laser pulse focussed on the dy e
layer of the disc.Where the laser pulse is a pplied,a "pit" is created and the reflectivity of the surface is reduced.
The signal representing the (digital) data is recor ded in the succession of these pits,separated by reflective
"lands" of unburned material.The current recording system (driv e + disc) is very sensitive to variations outside
the Orange Book specifications, particularly when writing at high speeds (12x and higher).

For example,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 otherwise defectiv e (as an
example,unequal deposition of material),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 ma y occur in reading ( "cross-talk" betw een tracks).

Thermo-Balanced Writing

Equally of course,if the pits come out too small or too light,then other reading errors can occur .If a CD-R
drive has no way of contr olling the burn process,to adapt itself to the nature of the media,then the use of such
sub-standard discs is far more likel y to result in defectiv e recordings and,more importantly ,severe End-user
disappointment.

Fig.1,Thermo-

Balanced Writing:

T ypical Heat Profile

during CD-R write

phase.Goal of TBW is

to ensure a correctly

balanced heat profile

during this phase.

Fig.2,Thermo-

Balanced Writing:

Pit & Land Cross

section. A build

up of Thermal

“cross-talk”during

successive “burns”

creates pits

with variable
dimensions,and
the possibility of

errors when data is

read back.

temperature

laser beam

required temperature to
burn a pit

diameter of pit is smaller
than diameter of laser spot

laser spot