Tag Archive for: Surface capacitive

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

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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

Can I hurt a touch screen by touching it? – Ben Harris, Cucamonga, CA

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Ah Ben, the question we Touch guys have always feared. I assume your question is akin to asking, “Does it hurt a tire if you use it on the road?” However, I think what you really mean is, “Does touching the screen wear it out”?

Well in the early days of touch (1970’s), some touch sensors did wear out when finger oils, ladies’ hand creams and Hawaiian-breezes corroded the thin films. (Hmm, wonder what those creams did to their hands?)

Today, all sensors are advertised to withstand a minimum of 5 million touches. It is even rumored that the president of one unnamed touch company (Microtouch) hired a homeless guy to actually touch the screen that many times. Each of the technologies wear out differently and there is a difference between electrical wear (it does not work anymore) and cosmetic wear (the display is hard to read).

The newest entry into the touch arena is also the most vulnerable to electrical failure. When the in-cell technology fails, it is going to take your display with it, so it’s a double whammy on the checkbook. This happens because you must actually touch and depress the LCD surface itself, which puddles the liquid crystal and scratches the first surface. (Remember your mother telling you to keep your hands off the TV?)

Surface capacitive is the most vulnerable to electrical wear. Touching the same spot multiple times will actually wear through the thin film, down to the glass substrate, rendering it non-linear. Of course, a big scratch from a diamond ring will do-it-in quickly. And bye-bye to SAW technology when that same guy puts a big ‘ol scratch in it too.

In terms of electrical and cosmetic failures, resistive 4-wire touch screens are the most vulnerable. Touching in one place will rub a shiny spot in the hard coat of the top polyester (PET) layer. Touching in this same spot will also wear and crack the top conductive layer and leave it an electrical basket-case. The same number of touches on a 5-wire resistive will not damage it electrically; however the same glossy spot will appear.

In the end, the winners in the wear-me-out contest are projected capacitive (p-cap) and Infra-Red which work without needing to touch anything. Nothing to wear, no electrical surface to scratch and thus these two touch technologies can advertise infinite electrical life.

So Benny, as is the case with that tire, there are 10,000 mile touch screens and 1,000,000 mile touch screens, it just depends.

Until next time,
Touch Guy

I need to use the most dependable touch screen for our new product, which one? – Gerry, Mooselookmequintic, ME

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Hey Gerry,

(BTW, is that really your town?), I like questions where I don’t have to give a wishy-washy answer. First, for the neophytes amongst you, there are five commercially viable touch technologies, from a list longer than the number of letters in your city….they are, Resistive (four types), Surface Capacitive (two types), Infrared, Surface Acoustic Wave (SAW), and Projective Capacitive or, as we affectionately call it, P-Cap, and you know as iPhone-type. (Those of you with corner-cameras, fibers on the edge, and in-cell systems, come back when you have real sales.)

Before I give you the answer, as the cognoscenti amongst you know, any touch technology will work for 80% of the applications, so those of you with the projects that need a specific type, dependability may not be the best question to ask. But the answer to which touch screen is most likely to be running in the morning, is, TA DA, P-Cap.

Why is it that Touch International has built millions of P-Cap touch screens over the last four years and not one has come back for non operation? The reason is that projective technology has nothing to wear out, the place you touch is just glass, which has a 9H scratch resistance (yeah, sapphire glass is better, but you can’t afford it), and the electronics are simple. With p-cap, the sensors are typically made the same way the safety glass windows in your car were made, so it is tough to break, which gives this technology the edge on the runner-up in the dependability category, which is SAW. The electronics are simple and minimal, which gives p-Cap a bigger edge over the third place (dependable touch) technology, which is infrared and its dozens of expensive emitters and phototransistors.

Touch International makes p-cap sensors from 1.8 inch to 22 inch, so, if the most dependable touch technology is your first priority, Gerry, my man, you know how to answer your cranky boss…just tell him P-Cap.

Until next time,
Touch Guy