CD player

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A Compact Disc player (often written as compact disc player), or CD player, is an electronic device that plays audio Compact Discs. CD players are often installed into home stereo systems, car audio systems, and personal computers. They also manufactured as portable devices. Modern units support other formats in addition to CDs, such as DVDs, CD-ROMs with audio files and video CDs. DJs often use players with an adjustable playback sampling rate to alter the pitch of the music programme. Many modern CD players also play MP3 CDs. CD playback functionality is available on all modern CD-ROM/DVD-ROM drive equipped computers as well as on DVD players and CD-ROM/DVD-ROM based game consoles.

1 Visual description
2 History
3 Subdivision
4 Operation
5 Functioning
6 Usage
7 Competitive products
8 Standards
9 Recent patents
10 External links
11 References

Visual description

Image:Vintagedenon.jpg

A 1980s era Denon CD deck.

Many CD players are contained in a plastic and steel casing which also houses the electrical system and the user interface.

The housing of a portable CD player also contains ports used to connect the player to a powered or unpowered speaker, headphones and/or a power system (see electrical wiring in the United States or in the UK). A portable CD player generally contains an internal power source in the form of batteries.

The housing of a stand-alone CD player contains speakers and perhaps a radio and/or tape deck. CD players used in component audio systems contain a power source, the user interface, and numerous ports to connect the player to the various parts of an audio system.

History

Tray Loading

Sony released the world's first CD Player called the CDP-101^[1] in 1982 utilising a slide-out tray design for the CD. As it was easy to use and manufacture, most CD player tray designs had followed this style of tray ever since. However there have been some notable exceptions.

Vertical Loading

During the launch of the first prototype CD player 'Goronta'^[2] by Sony at the Japanese Audio Fair in 1982, Sony showcased the vertical loading design of the CD player. Although the prototype's design was never really put into actual production, it was for a time adopted for production by a number of early Japanese CD player manufacturers including Alpine/Luxman, Matsushita under the Technics brand, Kenwood and Toshiba/Aurex. For the early vertical loading players, Alpine sourced their AD-7100 player designs for Luxman^[3], Kenwood and Toshiba (using their Aurex brand). Kenwood added their 'Sigma Drive' outputs to this design as a modification. A picture of this early design can be seen on the Panasonic website.^[4]

Top Loading

Image:Cd-player-top-loading-and-DAC.jpg

Top-loading CD player and external DAC.

In 1983, at the US and European launch of the CD format, Philips with their CD100 CD player (sold as Magnavox in the US), showcased the first top loading CD tray designs. The design had a clamp on the lid which meant the user had to close this over the CD when it was placed inside the machine. Apart from having no motors accessing a movable tray, thus interfering with the player's sound quality, as the disc was clamped right down within the player, it implied better sound quality. This was one of the primary reasons manufacturer Meridian created their MCD CD player,^[5] whose chassis design was derived from the Philips CD100.

Apart from being adopted on various stereo equipment designs such as mini components, over the years only a handful of hi-fi quality top loading tray CD players had been made. The most notable were Luxman's D-500 and D-500X series^[6] players, and Denon's DP-S1,^[7] both launched in 1993.

Tray Load with Sliding Mechanism

Meridians 200 and 203 players were the first players to adopt tray loading with sliding play mechanism. Basically as the tray came out to collect the CD, the entire player's transport system also came out as one unit. The players were also the first to utilise the CD Transport design whereby the audio electronics were separate from the CD drive mechanism itself to reduce jitter and distortion.

Tray Load with Dampers

A few companies produced CD players with dampened trays. The dampers were rubber grommets built into the tray to reduce distortion. Yamaha's CDX-1000 CD player was a good example of this design.

Slot Loading

Slot loading is the preferred loading mechanism for car audio head units, the Apple MacBook, PlayStation 3, amongst other audio players. There is no tray that pops out, and a motor is used to assist disc insertion and removal. Mini-CDs and non-circular CDs may have troubles with insertion and/or ejection.

Subdivision

Image:Optical Deck Bottom.jpg

Underside view showing a radial type tracking mechanism with screw drive.

Two types of optical tracking mechanims exist:

the swing-arm mechanism, originally design by Philips^[8] - the lens moves at the end of an arm, very much like the old turntables.
the radial mechanism, designed by Sony to avoid using Philips patent, which is the one used in most CD players nowadays (because it is cheaper) - the lens moves on a radial rail. It is also known as 3-beam linear tracking.

The swing-arm mechanism has a distinctive advantage over the other in that it doesn't "skip" when the rail becomes dirty. The swing arm mechanisms tend to have a much longer life than their radial counterparts. The radial mechanism works best for CD-Roms, though, as the speed of the disc increases.

Operation

The interface of a CD player does not vary widely from manufacturer to manufacturer. It is usually composed of a few buttons and a display device. Common buttons include play, pause, stop, advance/fast forward, back/rewind and, in the case of a multiple-CD player, disk selection. The display may provide information such as track number, track time, disk number in the case of multiple-CD changers and CD-Text.

Functioning

Image:Cd-player-explained.jpg

Teac CD player anatomy.

A CD player has three major components: a drive motor, a lens system, and a tracking mechanism. The drive motor rotates the disc between 200 and 500 revolutions per minute. The tracking mechanism moves the lens system along the spiral tracks in which information is encoded, and the lens reads the information using a laser beam, typically produced by a laser diode. The laser reads information by focusing a beam on the CD, which is reflected back to a sensor. The sensor detects changes in the beam, and interprets these changes to read the data. This data is output as sound using a digital-to-analog converter (DAC).

A subcode in an audio CD contains information on the total number of audio tracks, the running time on the CD, running time of each track, and other information. This information allows the drive motor to speed up or slow down as needed to read data at a constant rate.