Someting you probably didn't know!?

[RooTxBeeR]

I am learning to become a computer service technician at the moment, and am on a chapter teaching me all about the inter workings of a hard drive. I found out today that modern Hard Drives use a Voice Coil and motor to position the read/write head ( the part of the hard drive that reads information off of the Hard Drive Disk) on the disk inside a hard drive in order for it to read the data.

All magnetic hard drives made today employ a linear motor to move the actuator arms. The linear motor, more popularly called a voice coil motor, uses a permanent magnet surrounding a coil on the actuator arm. When an electrical current passes, the coil generates a magnetic field that moves the actuator arm. The direction of the actuator arm's movement depends on the polarity of the electrical current through the coil. Because the voice coil and the actuator arm never touch, no degradation in positional accuracy takes place over time. Voice coil drives automatically park the heads when the drive loses power, making the old stepper motor park programs obsolete.

Lacking the discrete steps of the stepper motor drive, a voice coil drive cannot accurately predict the movement of the heads across the disk. To make sure voice coil drives land exactly in the correct area, the drive reserves one side of one platter for navigational purposes. This area essentially maps the exact location of the data on the drive. The voice coil moves the read/write head to its best guess about the correct position on the hard drive. The read/write head then uses this map to fine-tune its true position and make any necessary adjustments.

Copyright 2008 by the Computing Technology Industry Association

^^ For legal reason since I took the above 2 paragraphs straight from my booklet.