Tag Archive for: resistive

Our team is developing a touch module for boats. This thing will be getting a healthy dose of sun, water, and sometimes saltwater. At the same time, it will need to do everything from finding fish to navigating the open seas, giving system diagnostics, and providing entertainment. I understand water can be a problem for touch screens. Why is that? What’s the best solution for me?

Ahoy Mate!

Nautical displays have traditionally topped the list of most difficult touch applications. It seems that boats and ships just have it in for touch. First there is the corrosive effect of salt water, so the legacy surface capacitive was out. Then there was the water itself, whether from rain or the stuff that floats-the-boats, which ended the possibilities for SAW, IR, and projected capacitive (PCAP). Resistive would work, but the internal reflections from the touch surfaces made sunlight readable displays really hard to pull-off and the image quality is really lacking. Plus, no multi-touch certainly makes it difficult to zoom in on that school of fish cruising 50ft below you.

So, Touch Guy picked this question as a vehicle for (unabashed?) self-promotion of his new PCAP Plus. It works great in boats, in fact, that’s what we developed it for in the first place. Rain, salt-water, and spilled coffee (or beer) are ignored. You get your pretty picture from that high-end LCD back. Even better for any military guys out there, now you can clamp down on that EMI so the display will not be a beacon for the bad guys missile (or maybe NSA spying). Right out of the box it passes both DO-160G and MIL spec 461. You retain the ease of multi-touch and get a system that will never wear out – whoa, you got it all. There is a small premium over standard p-cap, but PCAP Plus is a complete nautical touch display problem solver!!

Just remember the words of Robert Rose, “Ships are the nearest things to dreams that hands have ever made.”

-Touch Guy

How is TI’s new MulTI-Touch Projected Capacitive Technology able to work with water spray?- Tyler Womack, Wapakoneta, Ohio

So Tyler,

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,
Touch Guy

How should I pick a touch screen company? – Confused in Schenectady

Dear Confused:

Touch Guy is honored that you would pick him to say anything other than, “the only name you need to know is Touch International!” And Touch Guy will admit, after reflecting upon your question, coming up with an answer was daunting. There are more than 100, possibly as many as 200 touch screen companies around the world. They range from companies that focus on selling fully integrated systems all the way to “village” companies that somehow sell 4-wire touch panels at prices below the material cost.

First, because you are asking the question, Touch Guy will assume you are probably working on your first touch project and have not yet been swayed toward or against a specific touch solution (this is good because that means you have an open mind). To start, narrow down the types of touch technology that seem best for you. Read my white paper, “Choosing the Right Touch Technology,” check out products similar to yours to see what they use and then it is off to the web to search for suppliers. While there are several of types of touch, resistive, capacitive and IR have long been the top solutions. Less used but still common are acoustic and optical (camera). Resistive still rules but most new projects use the iphone-type technology called projected capacitive.

The touch screen business is very competitive so apples-to-apples pricing will not vary much. For complicated designs and touch-neophytes, the US suppliers are probably best and for routine, higher volume products, the Taiwanese are going to come through for you. For price, the Chinese suppliers will be your best choice but I suggest waiting until your second project to go that route.

In shorter words, see what your competitors are using, read about touch, call a supplier in your region, and find someone who sounds like they want to help!

Wow, that was a hard question.

Until next time,
Touch Guy