TouchGuy_Basic

Do you have a question for Touch Guy?

Send him an e-mail at asktouchguy@touchintl.com.

If I switch from a curved touch screen to a flat panel, will there be compatibility issues? Please Help! – Nicholas J. Kriz, Eden Prairie, Minnesota

Dear Mr. Kritz:

It is your lucky day! If you had asked for a single curved 13 inch touch screen, the answer would be iffy, because Touch International made their last resistive touch screen in that size more than ten years ago and we only make a few curved surface capacitive sizes now. But you are changing to a flat panel and you will find that most touch screens are backward compatible with ancient touch controllers (yep, that 13 inch display is ancient).

Here is how to stay in revenue production: First, find out if that round cable is a communication cable, or a touch screen cable. If it is a communication cable (most likely), then you need to unplug and open the monitor (bring beer and always wear eye protection). You can ignore that sticker about dangerous X-rays, but not the one about the high voltage. Once open, find the other end of the cable and get the name and part number for the touch controller so you can figure out what the compatibility requirements are.

You have a few options for how to acquire a new touch screen. You can contact the company that made your old touch screen, tell them the size of the LCD and they will sell you a new sensor which you can integrate in the LCD (using the old controller you removed from the monitor). An easier way is to purchase a touch integrated LCD monitor and you will simply plug in the RS232 (an old, old communication protocol) into the host computer. If the computer is as old as the monitor, there is a chance you will need a CGA (9 pin) to VGA (15 pin) adapter for the video connector. The third option is to use any touch technology you think best, but you will need to access the host computer to replace the touch driver with a universal touch driver from a company called TouchBase.

Have fun, enjoy the beer, and call Touch International if you have any problems.

Until next time,
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

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