h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I remember seeing something once (it may have been something on Tommorow's World) about a device that made a normal monitor into a touch sensitive screen. The device was a platform with weight and balance sensors. The idea was that when you push on the screen at a particular point the monitor moves very slightly. This slight movement was picked up by the sensors. The system converted the signals from the sonsors into a position on the screen. The drawback was that it would need to be calibrated before being used.

I remember that!...

Hmm... wonder what happened to it... where's my google... aha...

No sign of it. Hmm.

I have vague recollections of yet another system which involved a rectangular frame round an ordinary monitor... One each of the horizontal and vertical axes were solidly populated with infra-red LEDs, while the remaining two axes held long CCD devices, with optics to have each element focused in parallel to infinity, as used in some flatbed scanners. The software just interpreted the middle of the broken beam areas. Using a Trinitron screen, which is curved on one axis only, it had a very high resolution in the middle tailing off to left and right...

I think it was an article in "Hobby Electronics", "Practical Wireless" or somesuch... Google, anyone?

(And yes, I *know* that "CCD devices" is redundant. It's 3:30am - give me a break! )

Hmmm. Yes, we got taught about that type in computing A-level, so it must exist

The earliest Hewlett Packard touch screen PC used something that I didn't understand well but whose description sounds similar to that. It was made around 1983-ish.

Hi There,

The system was called Touch Mate. All Touch screens need calibration before use, but this needed more than others. It was a "force sensing platform" with electrostatic (ie Piezo) transducers built into the base (like a pizza box) on which the monitor stood. The tiny changes in force experienced by the transducers when the monitor was touched, were translated by the driver program into touch coordinates. The monitor had to be fixed very firmly to the base using a special clamp, any rocking or movement of the monitor was reported as a touch!

The neat thing was that you could have touch buttons outside of the screen area - on the bezel for instance. It also had the advantage of not having anything over the screen affecting the light transmission or image.

It was quite expensive compared to other technologies but when set up correctly it did work VERY well, great for "public domain" applications like musuems etc. where the monitor might be subject to misuse or vandalism and was cheaper to replace as the touch system was seperate to the monitor.

A leading Capactive Touch screen maker, 3M Microtouch (just Microtouch at the time), bought the rights and quietly killed it off, thereby eliminating a competitor!

Yes.....you've guessed it, I used to sell it!!

Hmm, thanks for that

Sadly, I can't think of any way that buying and killing of a small company is illegal. Nor any way to make it illegal. Shame... it's criminal, really. (And completely opposite to what 'Intellectual Property' laws are supposed to achieve).