Compact disc player - AbsoluteAstronomy.com

A Compact Disc player or CD player, is an electronic device that plays audio 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. CD players are often a part of home stereo

Stereophonic sound

The term Stereophonic, commonly called stereo, sound refers to any method of sound reproduction in which an attempt is made to create an illusion of directionality and audible perspective...

systems, car audio

Car audio

Car audio/video , auto radio, mobile audio, 12-volt and other terms are used to describe the sound or video system fitted in an automobile. While 12-volt audio and video systems are also used, marketed, or manufactured for marine, aviation, and buses, this article focuses on cars as the most common...

systems, and personal computer

Personal computer

A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

s. They are also manufactured as portable devices

Portable CD player

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...

. Modern units can support other formats in addition to CDs, such as DVD

DVD

A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....

s, CD-ROM

CD-ROM

A CD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback. The 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data....

s with audio files and video CD

Video CD

Before the advent of DVD and Blu-ray, the Video CD became the first format for distributing films on standard 120 mm optical discs. The format is a standard digital format for storing video on a Compact Disc...

s. DJs often use players with an adjustable playback speed to alter the pitch

Pitch (music)

Pitch is an auditory perceptual property that allows the ordering of sounds on a frequency-related scale.Pitches are compared as "higher" and "lower" in the sense associated with musical melodies,...

of the music programme. CD playback functionality is also available on CD-ROM/DVD-ROM drive equipped computers as well as on DVD player

DVD player

A DVD player is a device that plays discs produced under both the DVD-Video and DVD-Audio technical standards, two different and incompatible standards. These devices were invented in 1997 and continue to thrive...

s and CD-ROM/DVD-ROM based game consoles.

Tray loading

Sony

, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....

released the world's first CD Player called the CDP-101

Sony CDP-101

The Sony CDP-101 was the world's first commercially released Compact Disc player. The system was launched in Japan on October 1, 1982 at a list price of 168,000 yen....

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' by Sony

Sony

, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....

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

Luxman

Luxman is a brand name of Japanese , a company that produces a variety of audio electronic products. The company produces a variety of high-end hi-fi products, such as turntables, amplifiers, receivers, tape decks, CD players and speakers.-History:...

, Matsushita under the Technics

Technics

Technics may refer to:* Technics turntables, no longer in production.* Technics , a brand name of the Panasonic Corporation* An anglicization of the Ancient Greek term techne, used primarily in media theory...

brand, Kenwood

Kenwood

- Places :England* Kenwood , a part of Hampstead Heath, London, the location of** Kenwood House* Kenwood, in the parish of Kenton, Devon* Kenwood, St. George's Hill, John Lennon's home in Weybridge, SurreyUnited States* Kenwood, California...

and Toshiba/Aurex

Toshiba

is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and...

. For the early vertical loading players, Alpine sourced their AD-7100 player designs for Luxman, 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.

Top loading

In 1983, at the US and European launch of the CD format, Philips

Philips

Koninklijke Philips Electronics N.V. , more commonly known as Philips, is a multinational Dutch electronics company....

with their CD100 CD player (sold as Magnavox

Magnavox

Magnavox is a US electronics company founded by Edwin Pridham and Peter L. Jensen, who invented the moving-coil loudspeaker in 1915 at their lab in Napa, California. They formed Magnavox in 1917 in order to market their inventions....

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. This was one of the primary reasons manufacturer Meridian

Meridian Audio, Ltd.

Boothroyd Stuart Meridian is a British manufacturer of high-performance, high-fidelity audio and video components and systems. Founded in 1977 by Bob Stuart and Allen Boothroyd, its products have proved popular among music and movie enthusiasts, and more recently in the lifestyle technology and...

created their MCD CD player, 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

Luxman

's D-500 and D-500X series players, and Denon

Denon

is a Japanese electronics company that was involved in the early stages of development of digital audio technology, while specializing in the manufacture of high-fidelity professional and consumer audio equipment. For many decades, Denon was a brand name of Nippon-Columbia, including the Nippon...

's DP-S1, both launched in 1993.

Tray loading with sliding mechanism

The Philips CD303 of 1983-1984 was the first player 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 Meridian

Meridian Audio, Ltd.

s 200 and 203 players were of this type and also the first to use a design in which the audio electronics were in a separate enclosure from the CD drive and pickup mechanism.

Slot loading

Slot loading is the preferred loading mechanism for car audio head units, the Apple MacBook

MacBook

The MacBook was a brand of Macintosh notebook computers built by Apple Inc. First introduced in May 2006, it replaced the iBook and 12-inch PowerBook series of notebooks as a part of the Apple–Intel transition. Positioned as the low end of the MacBook family, the Apple MacBook was aimed at the...

, PlayStation 3

PlayStation 3

The is the third home video game console produced by Sony Computer Entertainment and the successor to the PlayStation 2 as part of the PlayStation series. The PlayStation 3 competes with Microsoft's Xbox 360 and Nintendo's Wii as part of the seventh generation of video game consoles...

, amongst other audio players. There is no tray that pops out, and a motor is used to assist disc insertion and removal. Mini-CDs

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...

and non-circular CDs may have troubles with insertion and/or ejection.

Pickup mechanisms

Two types of optical tracking mechanisms exist:

the swing-arm mechanism, originally designed by Philips - the lens moves at the end of an arm, very much like the old turntables.
the radial mechanism, designed by Sony, which is the one used in most CD players nowadays - 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.

Components

A CD player has three major mechanical components : a drive motor, a lens
Lens (optics)
A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...

system, and a tracking mechanism. The drive motor (also called spindle) rotates the disc between 200 and 500 revolutions per minute

Revolutions per minute

Revolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...

. 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

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...

. 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 processed, and eventually converted to sound

Sound

Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...

using a digital-to-analog converter

Digital-to-analog converter

In electronics, a digital-to-analog converter is a device that converts a digital code to an analog signal . An analog-to-digital converter performs the reverse operation...

(DAC).

A subcode

Compact disc subcode

Besides digital audio, a compact disc contains digital data called subcode or subchannel data, which is multiplexed with the digital audio. The data in a CD are arranged in frames. A frame comprises 33 bytes, of which 24 bytes are audio , eight bytes are error correction , and one byte is for subcode...

in an audio CD contains information on the total number of audio tracks, the running time on the CD, the running time of each track, and other information.

CD player features

CD players can employ a number of ways to improve performance, or reduce component count / price. Features such oversampling, one bit dacs, dual dacs , interpolation, anti skip memory, digital and optical outputs are, or were, likely to be found. Other features improve functionality, such as random play and repeat, or direct track access. Yet others are related to the CD player's intended target, such as anti-skip for car and portable CD players, pitch control and queing for a DJ's CD player, remote and system integration for household players. Description of some features follows:

Oversampling is a way to improve the performance of the low pass filter present at the output of most CD players. By using a higher sampling frequency , a multiple of the 44.1khz used by CD encoding, it can employ a filter with much lower requirements.

One bit dacs were less expensive than other types of dacs, while providing similar performance.

Dual dacs were sometimes advertised as a feature because some of the early CD players used a single dac, and switched it between channels. This required additional supporting circuits, possibly degrading sound quality.

Interpolation , while not usually advertised, is present in most recent CD players. Interpolation is a way to correct errors that may be present on a compact disc, perhaps due to dust, scratches or dirt.

CD changer

A CD changer holds multiple Compact Disc

Compact Disc

s, usually in a cartridge, and allows the user to access (or play) any of them, one at a time. CD changers were commonly found in home cinema

Home cinema

Home cinema, also commonly called home theater, are home entertainment set-ups that seek to reproduce a movie theater experience and mood with the help of video and audio equipment in a private home....

systems, in cars

Automobile

An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...

and, less frequently, in computer

Computer

A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

equipment.

External cartridge

External cartridge CD changers have one or more cartridges that the user loads with up to twelve different CDs (depending on manufacturer) and then inserts into the CD changer. The CD changer can then remove one CD at a time for playing. This type of player is commonly found in vehicles because the user can switch easily between large amounts of media contained in different cartridges.

Internal cartridge

Internal cartridge CD changers work on the same basic principle as external cartridge players, except the cartridge never leaves the CD player. This type of CD player accepts multiple CDs through a single slot and stores them internally.

Carousel

A carousel-type CD changer consists of a circular platter that holds three or more CDs. Traditional carousel CD players hold three, five, or seven discs on a flat carousel tray. The carousel ejects to allow access to the CDs. Once back inside, the CD changer can rotate the carousel to access all of the CDs. Such carousel CD changers often allow the user to rotate the carousel while open, and change all CDs if no CDs are currently playing, or to eject the carousel while one CD is playing to change any CDs accessible from that position. Another type of carousel CD player is the mega-disc or "jukebox" CD players as they are also known. They usually hold anywhere from 50 to 300 discs. The mega-disc CD player holds its discs in a vertical position in slots that are located 360 degrees around the carousel. When a disc is selected to be played, the carousel rotates so that the disc can be picked up by a pickup mechanism and placed in CD playback unit. Mega-disc CD players generally have a means of entering in titles of the CDs stored inside them, such as telephone style letter input system found on the remote control, a full letter keypad on the unit, or by use of an external keyboard attached to the unit. Many units can also automatically obtain the title of a CDs if it contains CD-Text

CD-Text

CD-Text is an extension of the Red Book Compact Disc specifications standard for audio CDs. It allows for storage of additional information on a standards-compliant audio CD...

info stored on it.

Computer-based changers

CD-ROM changers existed in the early 1990s as expensive external drives, often connecting through SCSI

SCSI

Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it...

interfaces.

Changers were in a period when the mean hard drive capacity was measured in hundreds of megabytes. After exponential growth of hard drive storage density, a single inexpensive hard disk drive has many times the capacity of a CD, and changers have fallen out of use.

External links

The Audio Circuit A complete list of all brands who've developed CD-players

Swing-arm pickup mechanism

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.