Hey Sign Guy,
The big ones, usually defined as over 32 inch LCD’s, have long been the domain of optical systems with an occasional sighting of an acoustic (external and internal noise generator) or surface capacitive sensor, as well as a smattering of the other touch technologies. Optical is defined as IR beam or corner camera type. Recent advances in optical touch systems have added the ability to do multi-touch which had been one of the drawbacks. Frankly sign guy, optical is your best choice today. But do not sign any long term commitments. The market wants p-cap with pen for large format displays. Why, you inquire? The same reasons the small display guys want it….low cost, high reliability/durability, multi-touch, gestures, and good image quality – in addition to the twelve other things people like about the technology. The holy-grail of big formats seems to be white-boards (think every school room and meeting chamber) as opposed to the slow growing digital signage market (for touch displays). But, as Touch Guy has pointed out, p-cap has changed the sleepy old days of resistive touch manufacturing to major advances every six months…..that 82 inch, $35,000 p-cap touch panel you saw at the trade show last year will be in your budget within 12 months. Already 32 inch p-cap is common and cheap, due to advances in the materials, IC’s, and manufacturing techniques. Passive pen is not quite ready for the big ’uns yet, but when it is, Touch Guy advises you buckle your seat belt.
Until next time,