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| Structure and Mechanism of recording and playback |
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Recording format using
organic dye material
(DVD-R and DVD+R) |
The format that records data through the creation of recorded
marks by changing the organic dye material with a laser beam.
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| -Disc structure |
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| < Conceptual drawing > |
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| -Recording principles |
[ Recording ]
Recording is done by changing the organic dye layer and the
substrate with a laser. When a strong laser is applied to a disc, the temperature
of the organic dye material goes up, the dye is decomposed. At this time, a durable
pit is created as is the case with a DVD-ROM.
[ Playback ]
Signals are read with the differences of the reflection of
a laser from pits. |
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Recording format using phase-change recording material
(DVD-RW and DVD+RW) |
Data is recorded by changing the recording layer from the amorphous
status to the crystalline status, and played back by reading the difference of
the reflection coefficient.
* Amorphous:
Non-crystalline
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| -Disc structure |
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| < Conceptual drawing > |
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| -Recording principles |
[ Recording ]
When a high-power laser is applied to the recording material,
it melts and then becomes amorphous with a low reflection coefficient when it
quickly cools off. When a mid-power laser is applied to heat gradually the recording
material and then gradually cools it off, it becomes crystal with a high reflection
coefficient.
[ Playback ]
A low-power laser is used for playback. The amount of reflected
light depends on the status (amorphous or crystalline) of the recording material.
This is detected by an optical sensor. |
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