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Disc Types
CDs
When discs were invented the process of
construction was quite simple. These are what
we call CD discs. To produce the disc, a solid
polycarbonate disc was made. Then the data layer
was applied to the top surface of the disc. To protect
this data layer, a lacquer, or label, was then applied
over the top of the data layer.
Polycarbonate
Data
Label
This made the data layer quite vulnerable because
any scratch to the label could damage the data layer
beneath. If a scratch has reached the data layer
it is not repairable. Disc repair can only repair the
polycarbonate on the underside of the disc.
Formats:
Audio Books
Audio CDs
CD-ROMS
Playstation version 1 discs
DVDs
The early CDs were mainly used for audio and so
often a small scratch was not enough to disrupt the
data. However as the data on discs became more
complicated it became more important to protect
the data layer. On DVD discs the data layer is
sandwiched in the middle of the disc between two
pieces of polycarbonate. This protects the data layer
and makes the disc virtually indestructible. The only
issue with this type of disc is that the two layers of
disc can separate around the whole in the centre of
the disc, although this is quite rare.
Polycarbonate
Data
Polycarbonate
Label
Because the data is so protected virtually all DVD
discs can be repaired by the disc repair process.
Formats:
DVDs
Playstation 2 discs
Xbox
Wii
DVD ROM
Blu-rays
With the invention of High Definition (HD) there was
a need to carry more information on a disc and soon
the data space on a DVD was not enough. Sony
solved this with the invention of the Blu-ray disc.
Hard coat
Polycarbonate
Data
Polycarbonate
Label
It is essentially the same as a DVD with 2 main
differences:
1. The polycarbonate on the bottom of the discs is
much thinner than a DVD and so the number of
times that the same disc can be repaired falls to
around 10-15.
2. The polycarbonate on the bottom of the disc
has a hard coated lacquer on top of it. This hard
coat reduces the chance of the disc being
scratched in the first place, but nonetheless
scratches can still happen.
Formats:
Blu-ray films
Playstation 3
Playstation 4
Xbox One
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