Sony RDR-GX7 Frequently Asked Questions Manual

What is DVD?
DVD stands for Digital Versatile Disc. It
is the next-generation optical media
successor to the CD that has taken the
world by storm, becoming the fastest-
growing video format ever. By
increasing the amount of storage
available on a single disc the size of a
standard CD and providing the means
for both PCs and consumer electronics
devices to read it, a person is able to
enjoy higher quality audio, video, and
more data storage than ever before.
And just as with the compact disc (CD)
and CD-R/RW formats, Sony has been
instrumental in leading the charge into
bringing DVD
viewing and
recording to the
masses.
Frequently Asked Questions about
Recordable DVD
How does a DVD work?
A DVD works in much the same basic way that a CD works: a laser in the drive reads
small pits on a single-layer optical disc and translates that into data. However, a
DVD drive uses a tighter laser with a more precise beam and a shorter wavelength
than a typical CD drive in order to take advantage of the DVD's smaller pits (.4
micrometers versus .8 micrometers for CD—approximately 1/10 the size of a strand
of hair) and narrower tracks. The result? The increased data density provides more
room to store information and quicker access to what is on the disc.
How does the drive burn a recordable DVD?
Burning a writable DVD is similar to burning a blank CD. In essence, a blank DVD
contains a series of organic dyes inside. When a laser heats up the dyes, a chemical
reaction occurs and this layer is enabled to absorb the laser. The laser is then free to
"burn" small data pits in the disc according to the data sent.
A rewritable DVD uses a different layer, one that uses a phase change process to
alter the reflective state of the disc to a light-absorbing state. This is reversible, and
thus the disc can be rewritten again and again—up to 1,000 times. Three different
laser intensities are used in this process: one to read (does not alter disc), a stronger
one to erase (to reflect the laser and not allow data to be written), and the strongest
to write (which changes the recording layer to absorb the laser and allow writing).
CD-RW works in a similar way, but using a different laser and larger data pits and
wider tracks.