A portable CD player is a portable audio player

Portable audio player

A portable audio player is a personal mobile device that allows the user to listen to recorded audio while mobile. Sometimes a distinction is made between a portable player, battery-powered and with one or more small loudspeakers, and a personal player, listened to with earphones.-History:Portable...

 used to play Compact Disc

Compact Disc

The Compact Disc is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage , write-once audio and data storage , rewritable media , Video Compact Discs , Super Video Compact Discs ,...

s. 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

Liquid crystal display

A liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....

, laser diode

Laser diode

The laser diode is a laser where the active medium is a semiconductor similar to that found in a light-emitting diode. The most common type of laser diode is formed from a p-n junction and powered by injected electric current...

, photocell, and a digital to analog converter.

History

In 1984, Sony was the first company ever to introduce 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

Electronic skip protection

Electronic skip protection is a memory buffer system used mainly in some portable Compact Disc players and all MiniDisc units.-Technology:...

, 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
   Headphones
   Headphones are a pair of small loudspeakers, or less commonly a single speaker, held close to a user's ears and connected to a signal source such as an audio amplifier, radio, CD player or portable Media Player. They are also known as stereophones, headsets or, colloquially, cans. The in-ear...
   
   

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-R

A CD-R is a variation of the Compact Disc invented by Philips and Sony. CD-R is a Write Once Read Many optical medium, though the whole disk does not have to be entirely written in the same session....

/CD-RW

CD-RW

A CD-RW is a rewritable optical disc. It was introduced in 1997, and was known as "CD-Writable" during development. It was preceded by the CD-MO, which was never commercially released....

 discs and play other formats such as MP3

MP3

MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...

-encoded audio.
The 8 cm CD

Mini CD

Mini CDs, or “pocket CDs” are CDs with a smaller diameter and one third the capacity.-Formats:Amongst the various formats are the* Mini CD single, a small disc. The format is mainly used for audio CD singles in certain regions , much like the old vinyl single...

 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

MiniDisc

The disc is permanently housed in a cartridge with a sliding door, similar to the casing of a 3.5" floppy disk. This shutter is opened automatically by a mechanism upon insertion. The audio discs can either be recordable or premastered. Recordable MiniDiscs use a magneto-optical system to record...

 players, flash memory

Flash memory

Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...

 players and audio devices with their own internal storage such as smart phones and the iPod

IPod

iPod is a line of portable media players created and marketed by Apple Inc. The product line-up currently consists of the hard drive-based iPod Classic, the touchscreen iPod Touch, the compact iPod Nano, and the ultra-compact iPod Shuffle...

, 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.