Wikijunior:How Things Work/DVD
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A DVD is a disc that is used for storing information that a computer can read. This can be a movie, music, television program or a computer game. DVDs look like compact discs as they are the same size but they store much more information in a different way.
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[edit] Who invented it?
The DVD was not invented by one person or company. Toshiba, Philips, Sony, and Matsushita Electric all helped to develop the technology used to make DVDs.
[edit] How does it get power?
A DVD player is powered by electricity. It reads the data on the media using a light called a laser.
[edit] How does it work?
DVDs are of the same shape and thickness as CDs, and they are made using some of the same materials and manufacturing methods. Like a CD, the data on a DVD is held in the form of small pits and bumps on the disc. A DVD is made of several layers of plastic. Each layer is made by injection molding plastic. This forms a disc that has tiny bumps arranged as a single very long spiral track of data. More on the bumps later.
Each writable layer of a DVD has a spiral track of data. On single-layer DVDs, the track always circles from the inside of the disc to the outside. That the spiral track starts at the center means that a single-layer DVD can be smaller than 12 centimeters if desired.
[edit] How dangerous is it?
The DVD is not dangerous by itself unless it is broken. Then the pieces are very sharp and could cut your fingers - or your feet if you step on them.
[edit] What does it do?
It records digital information that can be used by a DVD player or computer.
[edit] How does it vary?
The first DVDs could store around 4.5 Gigabytes, but later scientists found a way to make more layers so they could store more data. These are called "double layer" DVDs. But now there are two new types of DVDs called blu-ray and HD-DVD that store even more.
[edit] How has it changed the world?
The DVD has modernized the current generations of video playing devices into the digital age.
[edit] What idea(s) and/or inventions had to be developed before it could be created?
The DVD was seen as the next step from the video cassette. There are many inventions involved to make a DVD possible. First of all, the computer had to be invented. You'll realize this when you try to understand how DVD works. On a DVD disk there is coded in a binary form all the information one needs to record a picture.
