Shaking Hard Drives Instead of Spinning?

Twyko64 writes "A UK startup called Dataslide aims to develop 'hard drives' made of oscillating sheets of LCD-screen-like material with piezo-electronic actuators and many, many read:write heads. A 'hard drive' could be the same size and shape as an LCD screen. I wrote a this piece on Techworld about it."

Comments

Piezoelectric

[JaxWeb]

I've recently being doing a report for Physics on the Piezoelectric effect, and it is really interesting thing.

When you put a current through a piezoelectric material (e.g. Quartz), it vibrates. The oscillations are used to create sound in Ultrasound Transducers, and they are used in watches as a time measurement.

Conversely, if you mechanically compress a piezoelectric crystal, a charge will occur at the edges. This is used in Ultrasound to detect sound waves, in guitar pickups, and even in those cigarette lighters in cars.

You can read more about it at Wikipedia: http://en.wikipedia.org/wiki/Piezoelectric

Just thought this might interest someone.

Re:Piezoelectric

[ajlitt]

Right. Except the bit about the car lighters. Car lighters have a spiral of bimetal (a clad strip of two metals with dissimilar thermal expansion characteristics, see inside an old mechanical thermostat) that heats up as a circuit is completed between the center pin (12V) and the housing of the lighter socket. When the bimetal reaches a certain temperature, the bimetal spring twists and releases the pushbutton mechanism of the lighter, breaking contact with the 12V pin.

Piezoelectrics are used in grill ignitors and 'electronic' lighters. They all use the same principle: Basically a piezoelectric material is put at the business end of a small hammer mechanism (much like a center punch) that strikes after a certain amount of pressure is applied at the button. Since the voltage at the edges of a piezoelectric material is proportional to the change in pressure, the quick blow produces a high voltage spike. That spike is fairly low current, but above the breakdown voltage of the air between the two contacts in the igniter.

Interestingly, these lighter modules are great fun for zapping people. Since it's a low current, there's really no danger to using these. It's much like a static shock.

One nifty application is in electronic buzzers. While that in itself may not be very inspirational, the actual design is pretty slick. Many fixed-frequency buzzers use a piezo elememt that has a small 'island' in the conductor along one pole. That island of conductive material is connected to a third wire. This wire is used as feedback to the oscillator driving the buzzer. What happens here is that you have the speaker (the majority of the element) and a separate microphone in the same substrate, enabling you to get a consistent tone by forcing feedback through the element itself! Since the peak volume of the buzzer is achieved at the resonating frequency of the element, this scheme locks the buzzer to the loudest tone it is designed to emit without any tuning of any sort.



Also, check out some info on the 'net on the use of piezoelectrics in: SAW filters (surface acoustic wave), fuel injectors, crystal oscillators (not just for your Timex!), angular rate gyros, and micromanipulators such as scanning tunneling microscope heads.

An engineer

[flowerp]

The signal processing done to the analog signal from one read/write head is tremendous. The performance of modern hard drive comes from the signal detection algorithms and advanced error correction that is performed.

You simply cannot do this at low cost when you have got several thousand or million r/w heads.