Posts

What do you think is going to be the next “big thing” in the future of touch technology? – Paul Jones, Santa Cruz, CA

Dear Mr. Jones:

Now Touch Guy feels threatened! For many months he has been extolling the virtues of projected capacitive touch and now you think it might not be the good-for-everything solution. Ok, I will reluctantly look into the crystal ball, aka Touch International’s skunk works, to provide you the answers you seek.

In-cell technology has long been rumored to be the projected capacitive killer. With in-cell, the touch sensors are the pixels in an LCD display. By light or capacitance sensing, when the thin film transistors are not busy switching the liquid crystal material, they can sense touch and send the information back to the LCD controller. There are already two or three products using this technology but its complexities and cost have delayed large scale production.

Many people are experimenting with corner camera technology of the sort used in big touch displays. As cameras get smaller and cheaper, this technology holds promise for future use in hand-held devices. The advantage over projected capacitive is that it is better at integrating a standard pen into the system. Higher power and the need for ambient light, among other things, add to the difficulty of wide-scale integration.

Fiber bundles with one camera offer some benefit; so far, the cost of making a low profile product in volume has been evasive, but this technology offers the ability to sense a pen tip as well as two touch applications. Right now it lacks the ability to do true multi-touch, so it may lag.

You should remember that like these emerging technologies, projected capacitive is not static and may one-up itself. Pen input, proximity sensing (up to one meter) and no-touch-touch applications are on the way.

So now that you’ve seen “the future” don’t forget that Touch International’s MARS product, is available today and offers high resolution pen input and full multi-touch capabilities.

There are more than 2000 patents on touch sensing, so Touch Guy does not claim to know the future but he has no fear – projected capacitive is here to stay.

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

Is projected capacitive technology reliable when used outdoors in a marine environment where it will be exposed to rain, saltwater spray, bright sunlight, etc? What are the likely points of failure? – Charlie, Marblehead, Massachusetts

Hey Charlie:

This is a most appropriate question for national sock burning day because, as is the case with all good sailors, Touch Guy barbequed his socks and pledged to go shoe-to-skin all the way to the last blustery days of Fall.

Ah, but back to your question…Until recently, resistive touch was the only technology that was appropriate for marine applications. It could be fully sealed so that salt water was not able to corrode the protective hard coat, trigger a false touch or become impaired by a layer of salt.

The big problem with resistive touch is that the internal reflections make the display difficult to view in bright sunlight. Typically this problem is overcome by using a very bright backlight, a sun shroud or an expensive sunlight readable filter.

Projected capacitive technology is now the best outdoor solution because it does not have internal reflections and when optically bonded to the display, provides optimal readability. Some projected capacitive electronics are confused by salt water on the sensor but others are totally unaffected with by it – Touch Guy TouchGuy_Basiccan help with this critical ASIC (Application-specific Integrated Circuit) decision. And, if your marine vessel happens to be an aircraft carrier, it is easy to incorporate EMI and night vision filters into the touch sensor.

Other than lowering the boom on the sensor, there are no points of failure, although cold weather sailors will find that projected capacitive technology will not work with thick gloves. It is also important to note that you will need to seal and add a conformal coat to the circuit board to prevent corrosion.

So Charlie, let’s be sock-less ‘til November and get that projected capacitive touch screen on deck!

Until next time,
Touch Guy