Projected Capacitive is quickly becoming the leading multi-touch screen technology due to its ultra-clear optics, high accuracy and extreme durability. Check out Touch International’s new multi-touch video to see projected capacitive in action.
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,
I guess you know water can be a lot of trouble for touch screens. The most vulnerable is SAW which stops dead in its tracks, to the least vulnerable, resistive touch. Resistive can be sealed so that water does not get in between the PET and glass layers which allows for better performance with water.
The ultimate irony is that most touch screens work because humans are just big bags of salt water and the water in our bodies serve as the primary activating mechanism. The problem is that the touch screen must distinguish between you, the big salt water bag, and the salt water puddle. (There is one rare form of an acoustic touch system than operates in a fully submersible ocean environment, but Touch Guy will ignore that one for now because it is made by a competitor).
So Touch Guy, still the SUPER-CHAMPION of projected capacitive needs to come clean on water and multi-touch. And if you follow Touch Guy, you know his answer to most questions is, “it depends.” In this case, it depends a whole lot on which sensing IC (Integrated Circuit/Chip) you use. Most ICs will invariably yell, “I quit!”, when it gets a lot of water on it – check out your iPhone sometime. The best IC could be saying, “I love water!”, and works really well. The water-loving IC will even work covered in distilled water, but as the salinity increases (as would be the case on the ocean) a salt spray is as far as you can take it. So your projected capacitive fish finder will work on the local lake in a light rain, but bow-busting 40 foot ocean waves are probably a little much.
Still need to survive the salt water wave and keep on multi-touching? Then the Resistive MARS technology is the one for you. Silicone-sealed behind a water tight bezel, this touch screen can take that salt water puddle and keep on touching. Add sunlight readable filters to the MARS sensor and you are ready for a jaunt around the continent on the bridge of your new yacht!
Until next time,