Help with a "non-contact touch screen" question.

Hopefully someone with a techy mind can answer a question i have about touch screens.

A while ago there was a thread on here about the coming of touch screens but without the contact, the device would use sensors to register your finger rather than the pressure of your finger. I can't remember any more than that, exept that people said it would be a more hygenic way of using a touch screen.

Anyway this thread suprised me because while it seemed to be talked about as if this was the next big thing, i was sat here thinking to myself, "The new dukebox in my local pub has that already!".

We have this dukebox which has tens of thousands of songs on it. You have a touch screen QUERTY keyboard that you use to search for your chosen song.

However it's a pain to use as before you've even touched the screen, when your finger is a few millimetres away from the glass, it registers your key selection.

Can anyone tell me how this works please? It's supposed to be a basic touch screen as far as i know, i mean all it is is a pub dukebox.

Is it just a case of sensors on the keys?

Thanks for any help.....it's just really been bugging me, especially after the thread about sensor touch screens.

CX.

reply to post by CX


Hi search for 'projective capacitive touchscreens'

These are pretty old tech now, I have used them for around 10 years until they stopped making them. You could set the sensitivity from very close to a few cm away.


[edit on 3/7/2010 by LightFantastic]

It could be one of a couple different older technologies:

Projected Capacitive - A electric field is projected above the glass touchscreen which is overlaid on top of a display. Sensors detect a change in the field to register a "touch".

Infrared - Infrared Light Emitting Diodes (LEDs) are beamed horizontally and vertically across the display to create a field. Once the path of the beams are broken, an X and Y coordinate are given to register a touch.

Or it could be nothing at all.

One of my projects while I was still in college was connecting a 3x4 keypad to a microcontroller so as to register key strokes. My project nearly failed that time, the problem was the keypad was sending signals to the ucontroller before I even touched it.

Since my fingers were clearly inducing a voltage when they got close enough to the keys, I decided to fix the problem by making the keypad active low (means that by pressing a key the voltage going into the ucontroller goes to 0 as opposed to active high, when the voltage goes to 1), fair enough, that fixed the problem.

Now, I'm just saying something like this could be the case, but I seriously doubt a product would be released into the market with a flaw like that, so the other guys may be rigth.

Thank you all for the replies.

I should have known better than to think my local pub had some futuristic cutting edge technology.

CX.

reply to post by CX


After reading your post again the jukebox might me using something like Cypress semiconductor through glass sensors. These are discreet touch sensor buttons you can place behind a lot of materials to register a touch.