How Do CD’s Work?
By: Garrison Kinney
2004-2005
CD’s
•The disc is 1.2mm
thick
•120mm in diameter
•117mm of data area
•
•They can hold
783MB(Mega Bytes)
of digital data
CD’s
•CD’s can store up to 80 minutes of music
and up to 99 tracks
•It is made of an injection-molded piece of
clear polycarbonate plastic
The Bumps
When the CD is made is covered with
tiny bumps in an extremely long line
of data. These Bumps are the actual
music in digital form of 1’s and 0’s.
The Bumps
The bumps are
read by a laser and
put in a digital form
of 1’s and 0’s. The
raised areas, or the
lands, are 0’s and
the flat area, or the
pits, area are 1’s.
The CD Player
The main parts of a CD player are
the drive motor, the laser, the lens
system, and the tracking
mechanism.
The CD Player
The laser and the
lens system read the
bumps. The tracking
mechanism moves
the laser to follow
the bumps. The drive
motor spins the disc.
How the CD player Reads
the CD
The CD is covered in a reflective metal (usually
aluminum). The laser hits the bumps and the
laser is reflected to an opto – electronic device
that reads the digital data. The Digital
information is then put through a DAC(Digital
How the CD Player Reads the CD
You then have an electric signal that
humans can here. It is so quiet you can here
the sound. The signal is then put through an
amp so it is loud enough so you can here it.
After it goes through the amp it goes
through the speakers so you can hear it.
The CD Burner
The CD Burner laser moves the same way as
the read laser, from the inside out. CD’s with
no data on them that are waiting to be “burned”
are covered with a translucent dye.
How the CD Burner Works
The write laser “burns” the dye to simulate bumps.
The dye contains compounds of silver, antinomy,
tellurium, and indium. In order to rewrite on a CD
the laser must heat the dye to the melting
temperature of these compounds, which is 600
DEG. C.
CD Burner
When you heat the dye to
600 DEG. C, it will cause the
dye to melt, which makes the
dye translucent again. You
then can re burn the CD.
You must let the CD stay at
200 DEG. C, so the re burned
bump pattern will stay. This
process of letting the dye cool
is called crystallization.
About Me
My name is Garrison Kinney. I
am 13 years old. I love to play
basketball, watch movies, watch
T.V, swim and hang out with
friends. My favorite food is crab
legs. They are so good! I have
two cats. Their names are Hunter
and Savannah.
Brian, Marshall. “How CDs Work.” How Stuff Works.com.2005.26 April 2005
<http://electronics.howstuffworks.com/cd.htm>.
“Compact Disc.” Microsoft Encarta Online Encyclopedia. 2005. Microsoft Corporation.
27 April 2005 <http://encarta.msn.com/encyclopedia_7615649/Compact_Disc.html>.
Pohlmann, Ken C. The Compact Disc Handbook, 2nd Edition. Middleton, WI: A-R
Editions, Inc., 1992.
“Sound Recording.” The Kingfisher Science Encyclopedia. New York: Kindfisher
Publications, 2000.