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Question:

I’ve been hearing a lot about multi-touch these days – what’s the difference between resistive multi-touch and projected capacitive multi-touch and why would someone choose one over the other?

Thanks,

Mike Zimmerman, Charleston, South Carolina

Touch Guy's Response:

Dear Mike:

I am the long-time cheerleader for projected capacitive touch technology, so my answer may be biased, but here it is:

If you are a mechanic using a touch screen to fill out an overpriced car repair estimate, you should use resistive multi-touch touch screens (MARS); everyone else should use projected capacitive multi-touch technology (MulTI-Touch).

Touch Guy’s projected capacitive mantra is 1) it will never wear out, so it’s a better investment, 2) it has great optics and 3) it is multi-touch capable. The only downfall to projected capacitive technology is that it will not respond to every input device (i.e. pens, pencils, credit cards); only those that are conductive.

For all the mechanics out there, here is why you want to use Resistive multi-touch:

Let us assume that our mechanic, Mike, will use a torque wrench to reach over and activate the diagnostic machine’s touch screen – this requires a pressure sensing touch screen (aka resistive). Or when he fills out the repair estimate on an electronic recorder, he can use the nearby pen or pencil to input information. Mechanics will also like the palm rejection that MARS has. Palm rejection is achieved by ignoring touches in part of the screen and accepting them where the writing will occur (this is used in signature capture devices).  Plus, when every nano-watt counts, resistive technology consumes less power than capacitive.

But using resistive multi-touch technology comes at a cost when comparing it to projected capacitive technology. MARS is really just a 4-wire resistive touch screen cut up into severalf small 4-wire touch screens, so it will wear out with use. And the optics are not as good as projected capacitive because it has the same reflections of a standard 4 or 5-wire resistive touch screen. MARS-groupies point out that resistive touch has worked plenty-good for the last 25 years and the benefits of multi-touch, low power and no-drift coordinates make it a long term winner. Touch Guy is not convinced but thinks multi-touch resistive is a niche product.

Until next time, Touch Guy

Do you have a question for Touch Guy? Send him an e-mail at asktouchguy@touchintl.com.