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

I’m kind of new to the touch screen world and am trying to figure out why it is so difficult to get large (over 22”) multi-touch resistive and projected capacitive touch screens. Also, what are the big advantages and performance differences between the competing multi-touch technologies?

Hi Jim:

So you want to know about big ‘uns?

Projected capacitive, our favorite multi-touch technology, has pretty much topped out at 32 inch diagonal sizes. There are bigger ones available, but they have those annoying little wires that nobody likes to see.

In the realm of large format multi-touch, we find that infrared, camera (often called optical) and DST are the most commonly used touch technologies for large sizes (+32”), however IR and DST only support two touches. The mainstream projected capacitive and multi-touch resistive technologies are capable of unlimited touches, but are not as easily scalable (note that unlimited touch is controller-dependent, not sensor-dependent). So if you fancy yourself as Tom Cruise on a big 60 inch display, you will probably have to wait for projected capacitive to make it big.

So, what are we waiting for? We are waiting for transparent low ohm conductors. You will recall that projected capacitive is an X-Y scanned technology, using ITO for that purpose. But, white paper fans amongst you will recall that ITO has a relatively high resistance when compared to something like a copper wire. As the touch sensor gets bigger, the ITO resistance gets higher, and eventually, too high for the electronics to work. So, what is to be done?

TA DA! Debuting now, for your viewing pleasure, are nano-wires (think a Chinese population of angels on the head of a pin) and super-fine line copper webs. Both of these sport the required low resistivity, and only the most critical alien-eye can see them…. we can even coax them into rows and columns. Expect the electronics to grow as well, but, hey, what is an extra multiplexer or two…

So, Mr. Proctor, looks like your wait is over. Technology is getting bigger, not smaller, this time.

For even more info on multi-touch, check out Touch International’s Putting the ‘Touch’ in Multi-Touch White Paper and refer to the graph below.


– Touch Guy

Do you have a question for Touch Guy? Send him an e-mail at [email protected].