Tactile switches??

On a sunny day (Tue, 12 Apr 2011 10:07:24 -0700) it happened Tim Wescott wrote in :

Does not everybody these days use a touch screen? Then you can change the look depending on the environment too, like a cameleon. Have not tried one myself though, should put it on the list. Any good cheap ones?

For $ome rea$on a touch $creen i$n't alway$ the be$t an$wer.

As usual, it depends. Stiffness of the top lid (label?), closeness of neighboring switches, acceptable push force. Then the more practical side, for example can womoen with these ugly long glued-on fingernails push it?

In general you need it locally domed or have a meander "crease" around. The other option is cutout and plastic or rubber insert. In case of plastic make sure that it won't rattle, usually requires a tongue.

The best "how to" lesson comes from taking apart that $2.99 Yahtzee game and stuff like that. See how they dunnit.

Current touch screens on outdoor terminals seem to fail a lot, especially in colder temperatures.

Have you ever seen a touch screen cell phone with a fingernail gouge in the soft membrane?

Yikes!

I remember some CDC Plato terminals more than

Some touch screens used vectored beam break super close to the screen surface, which gave better resolution for drawing etc. Some early membrane types used rather large zones so their resolution was low, but good for menu items or multiple choice answers.

I seem to recall electrostatic and capacitive systems as well, with a hard glass and without the vulnerable membrane that can be gouged by a fingernail.

I agree that cost has probably been the biggest reason touch screens are only a nitch product, but WHY would such things really have to be so expensive and so nitchy? You'd think the technology itself would not really cost that much to produce.

I've got a GE kitchen oven with membrane switches and the plastic membrane actually split right along the circular edge of the cutout below the plastic membrane for the air gap.

Is this a one-off item, or something for production? There are some folks who will run you prototype membrane keypads for cheap. One such outfit (that I never actually used) was in Canada, and you could always find their ads in the back of Circuit Cellar magazines.

Next question: Do you need something custom? Or, can you make an off-the-shelf membrane keypad work for you application. I say that because some vendors offer "common" configurations, like telephone and calculator layouts, etc... Just make a decal and stick over it. (Some vendors even offer blank layouts, while others have insertable labels).

Now, if ANY membrane keypad is too expensive - I can tell you some horror stories when I tried to go the tactile individual switch route. Bottom line: Was not happy with results. Too cumbersome, too messy, hard to align and get to look right, easy to miskey (or no-key), etc.., etc...

I personally think the only thing those individual little tactile switch are good for are buried "reset" type switches mounted to a circuit board. For user entry --- forget it. (Just my opinion.)

-mpm

ed

Sorry - just read your earlier post. I see now this is for very low production work. (10-100 pcs / year)

How about :

You can get some nice, rugged, 3M vinyl decals to overlay the buttons. Any good sign shop can make them for you on their "printer".

You might even be able to scrape the numbers of this one:

Also, I recall seeing blank (and calculator, telephone, etc...) layouts in one of the big catalogs. (Mouser, DigiKey?)?

Could you live with a Greyhill keypad? Link:

Just a thought. Good luck!

-mpm

It all depends on the switch you use.

We used a switch with some near infinite cycle 'mccbf' mean cycle count between failures (essentially mtbf).

It had a stainless steel shroud around the switch mechanics, and gangs of them would all sit perfectly coplanar.

I used many of them to replace bad mouse switches on my now near impossible to find trackball. They are less than .5 inches square as to the footprint and have caps that snap on, or not.

You mount the switches on a PCB and mount the pcb to the back of the front panel with stand offs. You have to make the metal cut-outs BIG. Bigger than the switch post. The idea is to use the label membrane across that large hole to allow depression of the underlying switch.

In the past I used a grayhill that had an clear overlay. Was easy to cusomize. Digikey has a 1x4 instock $15

Cheers

On a sunny day (Tue, 12 Apr 2011 10:40:05 -0700) it happened Tim Wescott wrote in :

cameleon.

But it would be so much fun to try to program that.

cameleon.

Until the customer got upset over my bill being several times more than the estimate.

On a sunny day (Wed, 13 Apr 2011 09:26:45 -0700) it happened Tim Wescott wrote in :

cameleon.

I dunno, some time ago I looked for touch panels, and it was not even that expensive, small ones.

We will still have to see what your solution costs, inclusive any tooling etc.