Portable CD player

An early portable player, a Sony Discman model D121

A Philips portable CD player disassembled

A portable CD player is a portable audio player used to play Compact Discs. The first audio player released was the D-50 by Sony. The D-50 was able to play/pause, stop, rewind, and fast forward music all in one device. Portable CD players are made up of four main components: a liquid crystal display, laser diode, photocell, and a digital to analog converter.

History

In 1984, Sony was the first company ever to produce the industry's first portable CD player called the D-50. The CD player was released only one year after the introduction of CD's on the market, and since it began to do so well other companies started to release their own portable devices. One of the major problems with the early portable CD players was something called skipping. Skipping consists of the laser inside the CD player temporarily losing its place on the CD, interrupting playback. In 1993 a solution to this was Electronic skip protection, it is a simple system to reduce disruption of audio from mechanical disturbance of players.

Features

The basic features of a portable CD player are:

1. Play/Pause
2. Stop
3. Rewind
4. Fast forward
5. Hold (some models)
6. Liquid crystal display
7. Headphones

The play and pause feature allows the user to pause in the middle of the track (song) and resume it at the same place the listener left off at once the play button is hit again. The stop feature stops the track allowing the user to then switch tracks easily. The fast forward and rewind feature will either fast forward or rewind the track the amount of time you hold the button down. The liquid crystal display provides a visual of how much battery is left, what track (number) is currently playing, and the amount of time elapsed on the track. The headphones solely function to amplify the music so it can be heard. Some CD-audio players can read CD-R/CD-RW discs and play other formats such as MP3-encoded audio. The 8 cm CD provides a smaller alternative to the normal 12 cm CD (although with a lower capacity). Miniature players exist that only play this format.

How it works

A portable CD player reads the bumps and grooves imprinted on a CD using its lasers. With its photocell (a device that detects any sort of light reflection given off of certain area), it determines whether there is a reflection of light given off from the CD when the laser hits. Depending on the light reflection, the photocell will return a 1, if there is no reflection, or a 0, if there is any light refection. When its laser hits a groove on a CD, it will not reflect any light, making it a 1. When its laser hits a bump or any other surface on the CD , a light reflection will appear making it a 0. The series of data from 0-1 on the CD is then transformed by a digital to analog converter, to recreate the shape of a sound wave. The headphones then amplify the sounds and then the audio is now able to be heard.

Burned CD's Playback Problems

When burning a CD, the commercial CD, the burning from has pits and lands (engravings companies place on the CD's so they cannot be replicated) imprinted on it. When attempting to burn a CD from a commercial CD, the pits and lands are then turned into darken areas on the burned CD. With older CD players the laser cannot read these darkened areas making the CD unreadable. A solution to this is to burn the CD at a slower speed or use a different brand of CD's to see which works.

Future

While as of 2010 CDs remain a popular audio medium, portable CD players have seen competition from other forms of portable audio storage. MiniDisc players, flash memory players and audio devices with their own internal storage such as smart phones and the iPod, offer listeners alternatives to portable CD players. The ability to read MP3 CDs has allowed CD players to continue to compete against these alternatives, although standard CDs are bulkier.

See also

• CD player
• Portable DVD Player
• Discman
• Walkman