Flat Keypad?

Hi,

Does anyone have any info on flat keypads meaning no raised keys but touch sensitive? I think Zelco once had a calculator that used that but everywhere I look now I see physical keypads. My product design needs something that is printed on keys with no physical gaps or raised switches.

Something relatively cheap, not a touch screen LCD or anything like that. Hmmm…maybe conductive ink or other method???

Like this?
http://oldcomputers.net/zx80.html
:smiley:

would a “membrane switch” work in your app?

they’re not truely “touch sensitive” but they are flat, can have a tactile “click” if you want it, are waterproof, are comparatively cheap, and custom made to your spec.

http://www.millerdial.com/membrane-switch-domes.shtml

That Timex/Sinclair uses membrane switches like that used on ATM bank machines. Still very “thick” at about 3-5mm thick. The “thinnest” are capacitive circuit board traces on one side of a dual-layer PCB. It’s not as beautiful as a printed membrane, but it’s the most minimal.

:)ensen.

Actually it is for a clipboard type application of sorts so people can write on it and still feel it as a hard surface underneath (pens should not be able to punture it) but can also use the buttons. I guess tactile feel or response is not important so basically a hard plastic piece with printed keys that you don’t need to feel a tactile response to and won’t puncture if you write over it with a ball point pen.


Any suggestions?

Maybe something like this?
http://ernst.mulder.com/calculators/transparent-solar-index.html

I have seen other transparent calculators that use clear plastic and the keys are simply the silkscreened text

Barantec makes a line of piezo-electric switches for rugged applications, and environments which need to be cleaned well, like holpitals and hotel environments.

These switches can be totally flush to the surface, very thin, puncture proof, and contain no moving parts. The only downside to this is the cost, which is significant. If you’re looking at just a few switches (like a calculator) you’ll probably be fine (maybe 20-30 bucks for a calculator with minimal functionality and these switches). But, if you need a qwerty keyboard, you’re probably looking at hundreds of dollars just for the keys.

THanks for the info.

I will be like a calculator. But it has to be relatively cheap.

If it’s a calculator (like 15 buttons or less) you should definitely request a quote from those guys, or check on their standard line of numerical pads (I’m sure there’s a calc-type pad in there somewhere)

If you can, you should talk it over with an electrical engineer who has experience in toys (I’m Mech-E). Various toys which have sold at less than 20 dollars(with a 4X mark-up) have included up to 3 of these piezo-elements, so you might be able to pull it off.

Then again, that seems like it would be cutting it pretty tight for a 10-15 dollar price point (which is what a clipboard/calculator seems like it should cost at the max). Unless you have some other really valuable functionality in the clipboard, you should probably stick to a membrane keypad.

…you can get inexpensive membrane switches which will activate at 2oz with no perceptable travel and they could be overlayed with a thin aluminum sheet…

Check out www.eleksen.com. Look at their ‘Elektex Sensing Technology’ which uses X and Y layers of fabric over conductive textile to create a pressure responsive switch. Fab company looking for product designers to use their technology. :astonished:

try http://www.t-ink.com/

you could print not only your interface, but your whole circuit. doesn’t get any slimmer than that (for now)