What Are the Components of a CD-ROM Drive?
Nearly every household computer today has a CD-ROM driveinstalled. Not only are they used to listen to audio CDs from your favorite artists, but CD-ROM drives can also read any kind of computer data that has been written onto a CD. While this may sound like a simple task, many components must work together inside your CD-ROM drive in order to make this happen quickly and efficiently every single time.
The lens of your CD-ROM drive is responsible for reading CD data, which it does while the disc is spinning. If the lens of your CD-ROM drive becomes dirty, it may have a tendency to skip audio CDs and misread information from data CDs. In severe cases, the information may be completely unreadable.
The lens of a CD-ROM driver is positioned on a mechanical actuator. This moves the lens back and forth, allowing it to read data from the surface of a CD. This is controlled by an internal servo system and a dedicated microcontroller.
The spindle motor is responsible for spinning the CD when it is in your CD-ROM drive. The speed of a CD-ROM drive's spindle motor is dependent on the area of the CD that is currently being read. When reading data from the inside or center of a CD, the spindle motor runs faster. As the laser starts to read data near the outside edge of a CD, the spindle motor runs slower.
Disc-loading mechanisms of CD-ROM drives vary depending on the manufacturer. The most common disc-loading mechanism in use today is the tray loader. This is a simple plastic tray that slides out of the drive, allowing you to insert the CD into the drive. The tray keeps the disc in place while it is in the drive.
A four-pin power connector is located on the back of every CD-ROM drive; this is the same type of connector found on hard drives and most other internal devices. These drives also have an additional connector, depending on whether the drive is IDE or SCSI-based. A three- or four-wire cable is also on most CD-ROM drives, allowing for direct connection to your computer's sound card.
Internal Logic Board
The logic board of a CD-ROM drive controls the operations of the drive itself. The logic board has no serviceable parts.
Outputs and External Controls
Many CD-ROM drives are equipped with a headphone jack on the face of the drive, allowing you to easily plug in a pair of headphones. Other common controls include Start and Stop buttons and volume control dials.
A metal case is used to protect all of the components of a CD-ROM drive. Opening the drive enclosure may make it prone to damage.
References & Resources
- PC Guide: Optical "Head" Assembly
- PC Guide: Head Actuator Mechanism
- PC Guide: Spindle Motor, Constant Linear Velocity (CLV) and Constant Angular Velocity (CAV)
- PC Guide: Loading Mechanism
- PC Guide: Connectors and Jumpers
- PC Guide: Logic Board
- PC Guide: Audio Ouput and Controls
- PC Guide: External Packaging and Mounting