“Hey Touch Guy, why can’t the military use projected capacitive?” – Ready, aim, fire!
Whoa, simple question – complex answer.
First, the “military” does use projected capacitive (p-cap for short), and purchases a huge number of iPads and iPhones. But I think your question is, “Can the military use p-cap in a battlefield environment.” Yes, there are problems that have slowed the introduction of p-cap. Here are a few that need to be addressed, and are being overcome.
Most of the armed forces are very careful about generating EMI that could be detected by the bad-guys. P-cap, you will recall, works by having a human drain capacitance from the touch screen at the touch point. For multi-touch, that means lots of small fields are created on the surface of the touch screen. The fields are quite small, and inconsequential compared to the EMI from radios that are in most devices, but they are still there. TI has been able to tune the frequency to meet
EMI is a general problem, but it’s not alone in the obstacles p-cap must overcome. The Navy and Coast Guard, not surprisingly, want rain and sea-water immunity. Solutions have been developed in the electronics to compensate for tap and rain water. But sea water, because it is more conductive, is a more difficult matter because it spreads a conductive film across the touch area, and when a finger is touched to the screen the capacitance is drained from lots of points which confused the touch electronics. TI has developed a new total immunity sensor that works both mechanically and electrically to provide immunity to sea water.
Both the Army and Air Force require gloved finger operation. For most flight applications, the gloves are thin-enough that p-cap is a great choice. However, for some Army applications, the gloves are bigger and thicker and an accurate touch is more difficult…Touch Guy does not think this is a real issue because if the gloves are so big and bulky, how can you touch a small point anyway?
Impact, and the resulting breakage, is another issue, as most p-cap touch screens are made from glass. There is also a weight issue in using glass. The obvious solution is to make the p-cap sensor completely out of plastic or some form of acrylic substrate, however, plastic can scratch in some environments. Technology to the rescue, there are new transparent hard-coats for plastics that can approach the scratch resistance of glass.
In conclusion, Touch Guy believes the real roadblock preventing the introduction of p-cap into the battlefield isn’t the touch sensors themselves, but the lack of new programs that would make use of the latest and greatest touch technology has to offer.
Remember, I come in peace! – Touch Guy