What Is Inside a CD Writer?
Put a CD in a CD writer, and the writer can either read the data on the disc or write data to the disc in the form of computer files or music. We don't often think about all the parts inside the CD drive that make these capabilities possible, but every part is important in allowing the drive to function.
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Logic Board
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If you removed the entire CD drive from your computer, you'd see the logic board on the top of it. While not technically inside the drive, the logic board is hidden inside your computer where you can't see it. The logic board has a motor driver chip that powers the three motors in the drive, RAM chips, switches that open and close the drive tray and connectors for cables that carry data to the rest of the computer.
Three Motors
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A CD writer drive has three motors inside it. The sled motor moves the optical unit around as it reads the CD. The spindle motor spins the disc. And the tray motor operates the tray pulley, which opens and closes the tray that holds the CD.
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Optical Pickup Unit
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The optical pickup unit is a complicated piece of equipment that contains the important working parts of the CD drive. It has many parts: two rails that it rides on, two dampers, two focus coils and two tracking coils, as well as the lens, the photo diode and the laser diode.
Lens
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The lens is one of the most important parts of the CD drive. It has two focus coils that are operated by magnets to move the lens up and down to focus it. Two other coils, called the tracking coils, move the lens from side to side.
Laser
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The laser shines on the CD disc and its light is reflected back to be read by the lens. There are mirrors and beam splitters in the optical pickup unit that help with the reflection.
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References
- Photo Credit Compact disc in Drive image by Edward Stephens from Fotolia.com
