CD Burners

8/13/2019 CD Burners

1/12

How CD Burners WorkIn 2000, one of the biggest news stories was the rise of Napsterand similarfile-sharingprogramsWith these programs, !ou "ould get an #$% &ersionof 'ust about an! song !ouwant without shelling out a dime (he re"ord "ompanies were fairl! upset o&er this turn ofe&ents, and understandabl! so) (he! weren*t making an! mone! off the distribution of their

produ"t to millions of people

An external writable CD drive, also called a CD burner: Withthis type of drive, you can take music or data files from your

computer and make your own CDs.

But there was mone! to be made on the +Napster re&olution,+ as ele"troni"s manufa"turersand retailers soon dis"o&ered In , 2000 and earl! 200, sales of CD burners and blank

CD-.e"ordable dis"s sk!ro"keted /uddenl! it was feasible for the a&erage person to gathersongs and make their own CDs, and musi"-mi makers e&er!where wanted to get theirhands on the means of produ"tion (oda!, writable CD dri&es 1CD burners are standarde3uipment in new $Cs, and more and more audio enthusiasts are adding separate CDburners to their stereo s!stems In less than fi&e !ears, CDs ha&e e"lipsed "assette tapesasthe mi medium of "hoi"e

In this arti"le, !ou*ll find out how CD burners en"ode songs and other information onto blankdis"s We*ll also look at CD re-writable te"hnolog!, see how the data files are put togetherand find out how !ou "an make !our own musi" mies with a CD burner
http://computer.howstuffworks.com/napster.htmhttp://computer.howstuffworks.com/file-sharing.htmhttp://computer.howstuffworks.com/file-sharing.htmhttp://computer.howstuffworks.com/file-sharing.htmhttp://computer.howstuffworks.com/file-sharing.htmhttp://computer.howstuffworks.com/mp3.htmhttp://computer.howstuffworks.com/mp3.htmhttp://computer.howstuffworks.com/cassette.htmhttp://computer.howstuffworks.com/napster.htmhttp://computer.howstuffworks.com/file-sharing.htmhttp://computer.howstuffworks.com/file-sharing.htmhttp://computer.howstuffworks.com/mp3.htmhttp://computer.howstuffworks.com/cassette.htm


2/12

CD Basi"s) (he Bumps

If !ou*&e read How CDs Work,!ou understand the basi" idea of CD te"hnolog! CDs store

musi" and other files in digitalform -- that is, the information on the dis" is represented b! aseries of s and 0s 1see How 4nalog and Digital .e"ording Worksfor more information In"on&entional CDs, these s and 0s are represented b! millions of tin! bumps and flat areason the dis"*s refle"ti&e surfa"e (he bumps and flats are arranged in a "ontinuous tra"k thatmeasures about 05 mi"rons 1millionths of a meter a"ross and .! miles15 km long

(o read this information, the CD pla!er passes a laser beamo&er the tra"k When the laserpasses o&er a flatarea in the tra"k, the beam is refle"ted dire"tl! to an optical sensoronthe laser assembl! (he CD pla!er interprets this as a " When the beam passes o&er abump, the light is boun"ed awa! from the opti"al sensor (he CD pla!er re"ogni6es this as a#

A CD has a long, spiraleddata track. $f you were to

unwind this track, it wouldextend out .! miles %! km&.
http://computer.howstuffworks.com/cd.htmhttp://computer.howstuffworks.com/cd.htmhttp://computer.howstuffworks.com/analog-digital.htmhttp://computer.howstuffworks.com/laser.htmhttp://computer.howstuffworks.com/laser.htmhttp://computer.howstuffworks.com/cd.htmhttp://computer.howstuffworks.com/analog-digital.htmhttp://computer.howstuffworks.com/laser.htm


3/12

A CD player guides a small laser along the CD's data track.$n conventional CDs, the flat areas, or lands, reflect the light back to the laser

assembly( the bumps deflect the light so it does not bounce back.

CD Basi"s) (he $ath(he bumps are arranged in a spiral path, starting at the "enter of the dis" (he CD pla!erspins the dis" while the laser assembl! mo&es outwardfrom the "enter of the CD 4t astead! speed, the bumps mo&e past an! point at the outer edge of the CD more rapidl! thanthe! mo&e past an! point nearer the CD*s "enter In order to keep the bumps mo&ing pastthe laser at a constant rate, the pla!er must slow the spinning speed of the dis" as the laserassembl! mo&es outward

)he CD player spins the disc while moving the laser assembly outward from themiddle. )o keep the laser scanning the data track at a constant speed, the player must

slow the disc as the assembly moves outward.

4t its heart, this is all there is to a CD pla!er (he ee"ution of this idea is fairl! "ompli"ated,be"ause the pattern of the spiral must be en"oded and read with in"redible pre"ision, but the

basi" pro"ess is prett! simple

In the net se"tion, !ou*ll find out how data is re"orded on CDs, both b! professionale3uipment and the home CD burner

.eading CDsIn the last se"tion, we saw that "on&entional CDs store digital data as a pattern of bumpsand flat areas, arranged in a long spiral tra"k (he CD fabri"ation ma"hine uses a high-


4/12

powered laserto et"h the bump pattern into photoresistmaterial "oated onto a glass plate(hrough an elaborate imprinting pro"ess, this pattern is pressed onto a"r!li" dis"s (he dis"sare then "oated with aluminum1or another metal to "reate the readablerefle"ti&e surfa"e7inall!, the dis" is "oated with a transparent plastic layerthat protectsthe refle"ti&e metalfrom ni"ks, s"rat"hes and debris

)he different layers of a conventional CD

4s !ou "an see, this is a fairl! "omple, deli"ate operation, in&ol&ing man! steps and se&eral

different materials 8ike most "omple manufa"turing pro"esses 1from newspaper printingtotele&isionassembl!, "on&entional CD manufa"turing isn*t pra"ti"al for home use It*s onl!feasible for manufa"turers who produ"e hundreds, thousands or millions of CD "opies

Conse3uentl!, "on&entional CDs ha&e remained a +read only+ storage medium for thea&erage "onsumer, like 8$s or "on&entional D9Ds (o audiophiles a""ustomed to re"ordable"assettes,as well as "omputer users who were fed up with the limited memor!"apa"it! offlopp! disks, this limitation seemed like a ma'or drawba"k of CD te"hnolog! In the earl!*0s, more and more "onsumers and professionals were looking for a wa! to make their ownCD-3ualit! digital re"ordings

Writing CDsIn response to this demand, ele"troni"s manufa"turers introdu"ed an alternati&e sort of CDthat "ould be en"oded in a few eas! steps CD*recordable discs, or CD*+s, don*t ha&e an!bumps or flat areas at all Instead, the! ha&e a smoothrefle"ti&e metal la!er, whi"h rests ontop of a la!er of photosensitive dye

When the dis" is blank, the d!e is translucent) 8ight "an shine through and refle"t off themetal surfa"e But when !ou heatthe d!e la!er with "on"entrated lightof a parti"ularfre3uen"! and intensit!, the d!e turns opaue) It darkens to the point that light "an*t passthrough
http://computer.howstuffworks.com/laser.htmhttp://computer.howstuffworks.com/framed.htm?parent=cd-burner.htm&url=http://www.ee.washington.edu/conselec/CE/kuhn/cdaudio/95x6.htmhttp://computer.howstuffworks.com/offset-printing.htmhttp://computer.howstuffworks.com/tv.htmhttp://computer.howstuffworks.com/dvd.htmhttp://computer.howstuffworks.com/cassette.htmhttp://computer.howstuffworks.com/cassette.htmhttp://computer.howstuffworks.com/computer-memory.htmhttp://computer.howstuffworks.com/floppy-disk-drive.htmhttp://computer.howstuffworks.com/question287.htmhttp://computer.howstuffworks.com/light2.htmhttp://computer.howstuffworks.com/laser.htmhttp://computer.howstuffworks.com/framed.htm?parent=cd-burner.htm&url=http://www.ee.washington.edu/conselec/CE/kuhn/cdaudio/95x6.htmhttp://computer.howstuffworks.com/offset-printing.htmhttp://computer.howstuffworks.com/tv.htmhttp://computer.howstuffworks.com/dvd.htmhttp://computer.howstuffworks.com/cassette.htmhttp://computer.howstuffworks.com/computer-memory.htmhttp://computer.howstuffworks.com/floppy-disk-drive.htmhttp://computer.howstuffworks.com/question287.htmhttp://computer.howstuffworks.com/light2.htm


5/12

A CD*+ doesn't have the same bumps and lands as a conventional CD. $nstead, thedisc has a dye layer underneath a smooth, reflective surface. -n a blank CD*+ disc,the dye layer is completely translucent, so all light reflects. )he write laser darkensthe spots where the bumps would be in a conventional CD, forming non*reflecting

areas.

B! sele"ti&el! darkening parti"ular points along the CD tra"k, and lea&ing other areas of d!etranslu"ent, !ou "an "reate a digital pattern that a standard CD pla!er "an read (he lightfrom the pla!er*s laser beam will onl! boun"e ba"k to the sensor when the d!e is lefttranslu"ent, in the same wa! that it will onl! boun"e ba"k from the flat areas of a"on&entional CD /o, e&en though the CD-. dis" doesn*t ha&e an! bumps pressed into it at

all, it beha&es 'ust like a standard dis"

4 CD burner*s 'ob, of "ourse, is to +burn+ the digital pattern onto a blank CD In the netse"tion, we*ll look inside a burner to see how it a""omplishes this task

Burning CDs) 8aser 4ssembl!In the last se"tion, we saw that CD burners darken mi"ros"opi" areas of CD-. dis"s tore"ord a digital pattern of refle"ti&e and non-refle"ti&e areas that "an be read b! a standardCD pla!er /in"e the data must be a""uratel! en"oded on su"h a small s"ale, the burnings!stem must be etremel! pre"ise /till, the basi" pro"ess at work is 3uite simple

(he CD burner has a mo&ing laser assembl!, 'ust like an ordinar! CD pla!er But in additionto the standard +read laser,+ it has a +write laser+ (he write laseris more powerful than theread laser, so it intera"ts with the dis" differentl!) It alters the surfaceinstead of 'ustboun"ing light off it .ead lasers are not intense enough to darken the d!e material, sosimpl! pla!ing a CD-. in a CD dri&e will not destro! an! en"oded information


6/12

)he laser assembly inside a CD burner

:n the net page, !ou*ll find out how this write laser operates

Burning CDs) Write 8aser(he write laser mo&es in ea"tl! the same wa! as the read laser) It mo&es outward while thedis" spins (he bottom plasti" la!er has groo&es pre-pressed into it, to guide the laser alongthe "orre"t path B! "alibrating the rate of spin with the mo&ement of the laser assembl!, theburner keeps the laser running along the tra"k at a "onstant rate of speed (o record thedata, the burner simpl! turns the laser writer on and off in s!n"h with the pattern of s and0s (he laser darkens the material to encode a #and lea&es it translucent to encode a "

)he machinery in a CD burner looks pretty much the same as themachinery in any CD player. )here is a mechanism that spins the


7/12

disc and another mechanism that slides the laser assembly.

#ost CD burners "an "reate CDs at multiple speeds 4t speed, the CD spins at about thesame rate as it does when the pla!er is reading it (his means it would take !ou about ;0minutes to re"ord ;0 minutes of musi" 4t 2 speed, it would take !ou about half an hour tore"ord ;0 minutes, and so on 7or faster burning speeds, !ou need more ad&an"ed laser-"ontrol s!stems and a faster "onne"tion between the "omputerand the burner atits crystalliation temperature1around 200 degrees Celsius, it turns into a solid
http://computer.howstuffworks.com/pc.htmhttp://computer.howstuffworks.com/cassette.htmhttp://computer.howstuffworks.com/floppy-disk-drive.htmhttp://computer.howstuffworks.com/floppy-disk-drive.htmhttp://computer.howstuffworks.com/floppy-disk-drive.htmhttp://computer.howstuffworks.com/pc.htmhttp://computer.howstuffworks.com/cassette.htmhttp://computer.howstuffworks.com/floppy-disk-drive.htm


8/12

$n a CD*+W disc, the reflecting lands and non*reflecting bumps of a conventional CD arerepresented by phase shifts in a special compound. When the compound is in a crystallinestate, it is translucent, so light can shine through to the metal layer above and reflect backto the laser assembly. When the compound is melted into an amorphous state, it becomes

opaue, making the area non*reflective.

$hase-"hange CompoundsIn phase*change compounds, these shifts in form "an be +lo"ked into pla"e+) (he! persiste&en after the material "ools down again If !ou heat the "ompound in CD-.W dis"s to themelting temperature and let it "ool rapidl!, it will remain in a fluid, amorphous state, e&enthough it is below the "r!stalli6ation temperature In order to "r!stalli6e the "ompound, !ouha&e to keep it at the "r!stalli6ation temperature for a "ertain length of time so that it turnsinto a solid before it "ools down again

In the "ompound used in CD-.W dis"s, the "r!stalline form is translu"ent while theamorphous fluid form will absorb most light :n a new, blank CD, all of the material in thewritable area is in the "r!stalline form, so light will shine through this la!er to the refle"ti&emetal abo&e and boun"e ba"k to the light sensor (o en"ode information on the dis", the CDburner uses its write laser, whi"h is powerful enough to heat the "ompound to its meltingtemperature (hese +melted+ spots ser&e the same purpose as the bumps on a "on&entionalCD and the opa3ue spots on a CD-.) (he! blo"k the +read+ laser so it won*t refle"t off themetal la!er =a"h non*reflective areaindi"ates a 0 in the digital "ode =&er! spot thatremains "r!stalline is still reflective, indi"ating a

(he =rase 8aser4s with CD-.s, the read laserdoes not ha&e enough power to "hange the state of thematerial in the re"ording la!er -- it*s a lot weaker than the write laser (he erase laserfallssomewhere in between) While it isn*t strong enough to melt the material, it does ha&e thene"essar! intensit! to heat the material to the "r!stalli6ation point B! holding the material atthis temperature, the erase laser restores the "ompound to its "r!stalline state, effe"ti&el!erasing the en"oded 0 (his "lears the dis" so new data "an be en"oded
http://computer.howstuffworks.com/light.htmhttp://computer.howstuffworks.com/light.htm


9/12

CD-.W dis"s do not refle"t as mu"h light as older CD formats, so the! "annot be read b!most older CD pla!ers and CD-.:# dri&es /ome newer dri&es and pla!ers, in"luding allCD-.W writers, "an ad'ust the read laser to work with different CD formats But sin"e CD-.Ws will not work on man! CD pla!ers, these are not a good "hoi"e for musi" CDs 7or themost part, the! are used as back*up storage devicesfor "omputer files

4s we*&e seen, the refle"ti&e and non-refle"ti&e patterns on a CD are in"redibl! small, andthe! are burned and read &er! 3ui"kl! with a speeding laser beam In this s!stem, the"han"es of a data errorare fairl! high In the net se"tion, we*ll look at some of the wa!sthat CD burners "ompensate for &arious en"oding problems

CD 7ormatsIn the pre&ious se"tions, we looked at the basi" idea of CD and CD-burner te"hnolog! ?singpre"ise lasers or metal molds, !ou "an mark a pattern of more-refle"ti&e areas and less-refle"ti&e areas that represent a se3uen"e of s and 0s (he s!stem is so basi" that !ou "anen"ode 'ust about an! sort of digital information (here is no inherent limitation on what kindof mark pattern !ou put down on the dis"

But in order to make the information accessibleto another CD dri&e 1or pla!er, it has to been"oded in an understandable form (he established form for musi" CDs, "alled $/- 011#,was the foundation for later CD formats (his format was spe"ifi"all! designed to minimiethe effect of data errors

$hoto "ourtes!


10/12

=n"oding Data(here are a number of important aspe"ts in&ol&ed in making a CD readable to a CD pla!er)

(he CD tra"k is marked with a sort of timecode, whi"h tells the CD pla!er what part

of the dis" it is reading at an! parti"ular time Dis"s are also en"oded with a table ofcontents, lo"ated at the beginning of the tra"k 1the "enter of the dis", whi"h tells thepla!er where parti"ular songs 1or files are written onto the dis"

(he data tra"k is broken up b! etra filler, so there are no long strings of s or 0s

Without fre3uent shifts from to 0, there would be large se"tions without a "hangingpattern of refle"ti&it! (his "ould "ause the read laser to +lose its pla"e+ on the dis"(he filler data breaks up these large se"tions

=tra data bits are in"luded to help the pla!er re"ogni6e and fi a mistake If the

read laser misreads a single bit, the pla!er is able to "orre"t the problem using theadditional en"oded data

.e"orded information is not en"oded se3uentiall!> it is interlacedin a set pattern

(his redu"es the risk of losing whole se"tions of data If a s"rat"h or pie"e of debrismakes a part of the tra"k unreadable, it will damage separate bits of data fromdifferent parts of the song or file, instead of eliminating an entire segment ofinformation /in"e onl! small pie"es of ea"h file segment are unreadable, it*s easierfor the CD pla!er to "orre"t the problem or re"o&er from it

(railer (ra"kCD-.s and CD-.Ws ha&e a"omponent that ordinar! musi"CDs do not ha&e -- an etra bitof tra"k at the beginning of theCD, before time ero100)00,whi"h is the starting pointre"ogni6ed b! CD pla!ers (hisadditional tra"k spa"e in"ludesthe power memory area1$#4 and the powercalibration area1$C4 (he$#4 stores a temporar! tableof "ontents for the indi&idualpa"kets on a dis" that hasbeen onl! partiall! re"ordedWhen !ou "omplete the dis",the burner uses thisinformation to "reate the finaltable of "ontents

(he $C4 is a sort of testingground for the CD burner Inorder to ensure that the write

laser is set at the right le&el,the burner will make a series oftest marksalong the $C4se"tion of tra"k (he burner willthen read o&er these marks,"he"king for the intensit! ofrefle"tion in marked areas as"ompared to unmarked areasBased on this information, theburner determines the optimumlaser setting for writing onto thedis"


11/12

(he a"tual arrangement of information on musi" CDs is in"redibl! "omple 4nd CD-.:#/-- "ompa"t dis"s that "ontain "omputer files rather than song tra"ks -- ha&e e&en moreetensi&e error-"orre"tion s!stems (his is be"ause an error in a "omputer file "ould "orruptan entire program, while a small un"orre"ted error on a musi" CD onl! means a bit of fu66 ora skipping noise If !ou are interested in the &arious wa!s that data is arranged on differentt!pes of CDs, "he"k out4udio Compa"t Dis" - Writing and .eading the Data

With some writable CD formats, !ou ha&e to prepareall of the information before !ou beginburning (his limitation is built into the original format of CDs as well as the ph!si"al designof the dis" itself 4fter all, the long tra"k forms one "ontinuous, "onne"ted string of s and 0s,and it*s diffi"ult to break this up into separate se"tions With newer dis" formats, !ou "anre"ord files one +packet+ at a time, adding the table of "ontents and other unif!ing stru"tureson"e !ou*&e filled up the dis"

CD burners are an ama6ing pie"e of te"hnolog!, and the inner workings are "ertainl!fas"inating But to the t!pi"al "omputer user, the most "ompelling aspe"t of burners is what!ou "an do with them In the net se"tion, we*ll find out how !ou "an put all of this te"hnolog!to work and make !our own musi" mi

Creating


12/12

"opied onto a CD #ost are illegal "opies, howe&er, and it is a "op!right &iolation todownload them and burn them onto a CD (o sear"h for #$%-related Web sites, "li"k here

#$%s are compressed files, and !ou must epand 1decode them in order to burn themonto a CD /tandard musi"-management programs "an de"ode these files If !ou don*t ha&ethe right software, there are a number of de"oding programs that !ou "an download o&er the

Internet

:n"e !ou*&e gathered the songs, !ou "an use !our musi" manager to arrange them in theorder !ou want @eep in mind that !ou ha&e a limited amount of dis" spa"e to work with CD-.s ha&e &ar!ing capacities, measured in both megab!tes and minutes (hese da!s, mostCD-.s are either A minutes or 0 minutes long Before !ou mo&e on to burning !our CD,!ou should make sure that !our mi isn*t too long for the blank dis"

Creating

Documents

CD Burners