12
Sep
09

New Spin (or lack of) on hard drive technology


(Copyright 2009 – Kevin Rouviere)

This is an idea I’ve had for awhile, and while I don’t have a working system based on this idea, I can illustrate the principles.

Potential benefits:

– Maintain high recording density

– Dramatically reduce power consumption

– Instant start/stop of data storage device

The storage device can be built using conventional hard drive technology, with minimal changes to the mechanics. The spindle motor is replaced with a servo motor to provide precise angular positioning of the platters. The head actuator is then used to sweep the head back and forth across the platters, to create relative motion between the read/write head and the recording medium. The read/write head would be rotated to provide proper alignment of the head with the recording tracks. The recording tracks would not be circular as in a conventional hard drive, but would rather be stripes extending from the innermost portion of the platter near the hub, toward the outer edge of the platter.

Using this technique, the economical method of storing data on hard drive platters could be combined with very low power consumption when the drive is not in use, because the platters would not need spin, other than to provide the correct angular position of the platters under the read/write head. When data storage or retrieval is needed, rapid startup may be achieved due to the short time needed to engage the read/write head actuator.

hdrive

Elements of the experiment – An old hard drive, Stepper motor (to drive spindle), wires soldered to voice coil.

CIMG2303

Short clip showing approximation of how device would work. Platter can remain motionless while voice coil provides required head velocity to read/write the platter.

 

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2 Responses to “New Spin (or lack of) on hard drive technology”


  1. 1 George Felendorf
    November 18, 2009 at 7:05 pm

    Hi,
    Hard disk drives were also called “Bernouli Drives” because they use the Bernouli principle to entrain a fluid (gas, usually nitrogen or air) between the spinning platter and the read/write heads which quite literally “fly” over the platter. The key feature is that when flying in the fluid stream generated by the spinning platter, the heads are actually drawn toward the platter surface to a precise height above the platter when the gas between the head and platter are pressurized enough to keep the heads from ever actually touching the spinning disk.

    The intermittant piston-like motion you describe may not generate enough mption in the gas inside the drive to act as a “fluid bearing” so precise head to recording medium will have to depend on sturdier mechnical head mechanisms. The beauty of the bernouli approach is heads can be made very light, hence easier to move and high recording densities are achieved by very close head to platter distances being maintained by — Physics!.

    Soon, solid state drives may make all this moot.

    Cheers.
    George.

    • 2 krouviere
      November 27, 2009 at 2:44 pm

      Thanks for the comment! I’d considered the fact that the heads touch the platters in my example, whereas in a regular hard drive they float. I remember the earlier days of hard drives where the platters were much more fragile. I thought perhaps if this were used intermittently for devices such as battery powered data loggers or something that needed to start quickly, store/get a chunk of data, then stop (and go back to zero power usage), it might be ok since the total number of passes over the platters would be less than a drive that is constantly rotating. In my example the head would have to be re-design anyway in order to be properly aligned with the motion.

      This was just a crazy idea I had while playing with some HDD head servos.

      I agree, solid state drives will make this all moot 🙂

      Thanks!
      -Kevin


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