Philips Portable CD Player Compact Disc Recordable User Manual

Thermo-BalancedWriting  
Thermo-BalancedWriting  
Therm o Balanced W riting  
fo r o p t im a l r e c o r d in g  
 
Thermo-BalancedWriting  
temperature  
Fig.1,Thermo-  
BalancedWriting:  
laser beam  
Typical Heat Profile  
during CD-R write  
phase.Goal ofTBW is  
to ensure a correctly  
balanced heat profile  
during this phase.  
required temperature to  
burn a pit  
diameter of pit is smaller  
than diameter of laser spot  
laser spot  
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 controlling the burn process,to adapt itself to the nature of the media,then the use of such  
sub-standard discs is far more likely to result in defective recordings and,more importantly,severe End-user  
disappointment.  
Fig.2,Thermo-  
BalancedWriting:  
Pit & Land Cross  
section. A build  
up ofThermal  
“cross-talkduring  
successive “burns”  
creates pits  
with variable  
dimensions,and  
the possibility of  
errors when data is  
read back.  
 
Thermo-BalancedWriting  
Unfortunately,there is no reliable way a consumer can judge what he or she is buying (as example,an  
authoritative quality logo on the disc packaging or verification of media confirmance),and so when an End user  
buys and "burns" what are,in effect,sub-standard discs,any resulting problems are liable to be attributed more  
often to the CD drive unit then to the disc.It is a question of compatibility,something the End user implicitly  
desires,and unfortunately,is not able to recognise whether it is there or not.  
The solution  
Philips,anticipating End user concerns about disc compatibility and data integrity,has applied considerable  
effort to developing and testing a system of self-calibration for recording CD-R discs. This solution is "on  
board" in the drive itself,and provides an excellent solution. It is part of a continuous Philips programme  
devoted to the perfection of CD technology,and particularly,to anticipating and solving End user problems,  
thus enabling greater Ease of Use.  
The Philips solution lies in a technique designatedTBW [Thermo-BalancedWriting],a feature which is to be  
introduced in all new Philips CD-RW drives.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.  
CD-RW drives also write CD-RW discs of course,however,TBW technology is not applicable to the RW  
function as CD-RW discs utilise a completely different recording methodology.  
TBW allows many discs of lower quality to be used without anxiety,and with the assurance that the drive will  
automatically determine the integrity of the recording layer,then automatically select the correct burn  
conditions and associate these always with the optimal appropriate recording speed to ensure compatibility.  
The process is similar to the way in which modern fax machines communicate to detect what kind of partner  
machine is at the other end of a connection so that the two can transfer data properly without the user having  
to guess what might be there and press buttons to set up the link.  
The heart of the Philips solution is a new hardware and firmware built into the drive with theTBW algorithm  
which evaluates the disc and determines the burn parameters.  
The intelligent algorithm  
When a disc is inserted in the drive with intention to write,the start logic immediately triggers the partner to  
TBW,the self learning algorithm.In a brief interval of time,unnoticed by the End user,a sequence of physical  
tests are performed on the disc to determine its’ characteristics.  
On insertion,a test is automatically made in which 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 corresponds,  
within the tolerances allowed,then the disc is passed for recording under those conditions.  
 
Thermo-BalancedWriting  
If this initial test shows some discrepancies,then the algorithm goes to its main sequence.In one or more test  
burn/read iterations the required burn pulse data is recalculated,and if necessary,the disc is reassigned to the  
next lowest drive speed available.The calibration stops when the results show a correct performance within  
defined tolerances. The disc is then recorded with the revised conditions.  
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 theTBW intelligent CD-RW drive itself discovers to have  
been inserted in the disc tray.  
After final testing,recording can begin and the burn process 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. Thus the drive  
maintains a high degree of accuracy in writing,readability and above all,compatibility.  
Note,as well as intelligently calculating the optimal burn parameters,the choice of disc speed is made  
automatically without any intervention by the user. The user is always assured of a disc being recorded under  
optimal conditions.  
End-users may notice that recording takes place slower (or faster!) than expected (e.g.compared to the  
information on the disc packaging) but they should almost never see a wasted disc resulting from a recording  
failure due to this type of problem. As expected,end-users are informed via the application of the new selected  
recording speed.  
In other words,theTBW 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 theTBW feature.This makes for greater reliability,  
and longer useful life of the drive itself.  
The advantage is real  
Extensive development and testing of theTBW and Self Learning features was done in the Philips Research  
Laboratory in the Netherlands,and Philips Development Centre in Belgium. The testing is ongoing,and covers  
most CD-R media currently available on the market,and has demonstrated the real advantage of Philips  
solution. Most sub-specification CD-R media can now be satisfactorily written and read with a very limited  
chance of rejection.  
In addition to satisfactory practical tests,objective evidence of the reality of the quality obtained byTBW can  
be demonstrated (see Fig.3).TWB also forms the basis of a new proposed effort aimed at high speed  
recordable media standards.  
 
Thermo-BalancedWriting  
Fig.3 (Fig.3a & 3b),  
Thermo- BalancedWriting:  
Thermal“cross-talkis  
reduced byTBW.  
fig 3a: Without TBW  
fig 3b: WithTBW  
Pit  
Pit  
The standard for Pit and Land length is represented by an intersection of the horizontal and vertical lines. The plots,  
representing the individual measurements of each Pit and Land, in ideal circumstances (nocross-talkas example),  
should be located on the intersections themselves.  
The blackdotsin the illustrations represent the average of the measurements of Pit and Land length,and optimal  
writing would place the black dot on or very near each intersection.  
The two charts,one withoutTBW writing,and one with,clearly demonstrate an improvement in writing accuracy with  
TBW technology especially at the 3T up to 5T pit combinations.(The 3T up to 5T pit combinations are used for approx.  
70% of instances of writing data to disc).  
The new Philips 12x8x32x CD-RW is the first product to have been introduced utilisingTBW technology and  
from now,all Philips 8x4x32x CD-RW drives have this feature.  
To sum m arise  
TBW intelligent drive technology,developed and patented by Philips,is a powerful new feature that adds  
significant End user benefit. End user confidence in recording CD-R discs is assured by a state-of-the-art drive  
that can create recordings on previously questionable discs.Data integrity is assured by physically testing each  
disc and then tuning the output of the recording laser and choosing the recording speed to suit each individual  
disc. Even if the drive determines to use a recording speed lower than the maximum possible,it will always  
choose the maximum speed which can safely be used for the disc inserted. New discs are likewise  
characterised and then written to in accordance with their measured characteristics.  
These methods result in an "intelligent" drive,which adapts its behaviour to suit the precise requirements of  
each individual disc,ensuring the best possible recording quality on all media.It provides a very high success  
rate even when recording on discs of a quality below the internationally recognised standards.  
TheTBW technology is developed,qualified and already in production.  
 
Thermo-BalancedWriting  
Philips O ptical Storage  
Building SFH3  
P.O.Box 80002  
5600 JB Eindhoven  
The Netherlands  
© 2001 Royal Philips Electronics N.V.  
All rights reserved.Specifications are subject to  
change without prior notice.Reproduction in whole  
or part is prohibited without written consent of the  
copywright owner.  
3104 145 550 901  
Printed inThe Netherlands 2/01  
 

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