How Does a CD Player Work?

Today there is a wide range of CD players available for the consumer and choosing the right CD player can feel like an arduous task. Style, quality, design och technical solutions vary greatly between the different players. Some players are portable; others are included in larger sound systems. Some players can only handle one disc at the time; others can easily skip between 50 discs or more. Some CD players are very cheap, others are highly expensive. The list goes on and on. Regardless of which CD player you choose it will however consist of three basic parts that are found in all moderns CD players: a drive motor, a tracking device and a laser and lens system. Another thing that all CD players have in common is that they interpret data that has been stored in the form of elongated bumps on a CD (compact disc).

The drive motor in your CD player is the part that makes the disc spin round and round at a correct pace. The drive motor will gradually adjust the speed, since the correct pace depends on which part of the disc that is currently being interpreted. At some spots, the pace will be no higher than 200 rpm, while at other spots the pace needs to be increased up to 500 rpm. As the disc is rotated round and round by the drive motor, the tracking mechanism will adjust the laser assembly and make it possible for the laser and lens system to focus on the miniscule bumps where data has been stored. The laser is constantly being pushed from the centre and outward over the disc by the tracking mechanism.

The data interpreted by the laser and lens system has been stored in the form of elongated bumps on the surface of the CD. One single bump is very small and no wider than 0.5 microns. The height is greater than 125 nanometres and the length is 0.83 microns or slightly more. All these bumps are very neatly organised at the surface of the CD in the form of a 5 kilometre (3.5 miles) long spiral.

The CD itself is made up by several different layers, including a polycarbonate layer and an aluminium layer. When the laser tries to interpret data that has been stored on the CD, it will first penetrate the polycarbonate layer. The aluminium layer will then reflect the laser beam, and the light alterations will be detected by a special optoelectronic mechanism in the CD player. Since the bumps in which data has been stored reflects light in a different way compared to the areas between the bumps (commonly referred to as “lands”), the CD player can determine exactly which parts of the disc that is made up by bumps and which parts that are not.

If a CD is scratched or injured in any other way, it can be impossible for the CD player to interpret it. Sometimes only a minor part of the data will be skipped, but larger damages can render the entire CD useless. Always store your CD’s in a protective casing to decrease the risk of scratches. When you clean your CD’s, carefully move your hand from the centre and outwards to the edge rather than just swabbing around. Scratches that occur from a radial movement tend to be less damaging than other scratches.

The information you just read about CD players can be applied to most types of optic drives and can not only help you pick out a CD player for you home but also other types of optic drives such as car CD players and car DVD players.

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Why Do My Burned CDs Not Play In My CD Player?

So you just burned a mix CD of your favorite tunes for a road trip you and your friends are going on. You play the disc back on your computer, everything works like a charm. You might have even tried playing it back on your new home stereo, and just like on your computer, it plays fine. You head out, pop the CD into your car stereo you bought in 1998, and………nothing. The disc just spins and you get no playback. I’ve had this happen to me on numerous occasions. And have always wondered, why does my CD play on some players yet not on others? There are a few different things that factor into this.

1. CD-R vs. CD-RW.

You should be burning your audio CDs to CD-R media, not CD-RW media (CD re-writable). Some newer players will play CD-RW discs. But for the most part, the majority of audio CD players will only play CD-R discs.

2. Burn speed.

Each brand of CD-R has a certified maximum burn speed, which is expressed as a multiple of the audio playback speed. So, a disc certified at 24x can be burnt at 24 times faster than the audio CD will be spinning when it is played. You must set the burn rate in your CD duplication software according to the disc’s specification, or the data will not be written reliably. This can result in skips, or CD-Rs that will play to a certain point and then just stop. Ideally you want to burn your CD lower than the certified speed, to take into account manufacturing defects in your burner or the disc.

3. Brand of CD-R

If you have been burning CDs for a while, you probably have noticed that some brands of CD-Rs work well in some players, and some do not. CD-R discs are said to be “burned”. When you burn a CD-R disc, a focused laser beam darkens the chemical dye on your disc to mimic the bumps and flat spots that are generated on a replicated disc. (For more info on the differences between burning (CD duplication) and pressing (CD replication), please read my last article.

http://ezinearticles.com/?The-Differences-Between-Short-Run-And-Long-Run-Cd-And-Dvd-Duplication-And-Replication&id=158412

Unfortunately, sometimes the mimicry is not perfect. And if you have an older CD player that was not designed to play CD-Rs, it will not always play them reliably.

By all means this is not a complete guide for troubleshooting your CD burning problems. But it should at least give you a little more insight into why those darn mix CDs you burned will not play in your home or car stereo! My best advice is that you burn your CDs according to the certified maximum burn speed (lower if possible), and try out different brands of CD media until you find one that works best in your player.

About The Author
Jason Cole and http://www.DiskFaktory.com offer great tips and information regarding CD DVD Duplication Get the information you are seeking now by visiting http://www.diskfaktory.com/tips/CD-duplication-tutorials.asp.