Showing what is rarely noticed with coated touch displays

Klaus Wammes, Managing Director of Wammes & Partner, and one of the drivers behind the idea of the Electronic Displays Center in Gundersheim, Germany explained: "Dust that occurs during manufacturing processes can, among other things, scratch the display or make it completely unusable. In humid environments, however, mold may form in the interior. Coatings make displays not only more robust and less vulnerable to external influences and vandalism. They may even protect against disease. For example, in medicine, when many fingers are pounding on the same devices. More abstractly formulated, the interaction of display components can be compared to a car: If the windows are replaced by armored glass, shock absorbers, brakes and co. must also be adapted.”

According to him, every new combination of installed elements has to be revaluated and implemented appropriately. Replacing parts by following to the motto ‘old to new’ is not possible without further ado. For example, the impractical ITO layer (indium tin oxide) for touch sensors in curved and bendable displays is replaced by silver or carbon nanotubes.

If, however, their special properties are neglected, the result may be misinterpretations of signals, since the evaluating algorithm can no longer understand the user's command. This may not really have a dramatic effect on tablets, smartphones and other commodity displays or systems. Still, it can lead to dramatic errors in industrial applications due to disregarded latencies or ghost touches, which are by the controller or algorithm misinterpreted touch signals without actual user input. The supposed cure-all remedy PCAP must therefore also be reinitialised, calibrated or updated after an additional or altered coating.

The central problem with coated displays are the external influences on them: for example (dirty) fingers, moisture, dust and dirt. This also affects mainstream products. The algorithm in the microcontroller, the brain under the built-in components, must therefore be able to detect whether a command comes through a touch or whether interference factors shift the charges.

The higher the artificial intelligence and the computing speed of the controller, the better and safer the touch sensor is. It therefore helps to know how many touches or charge shifts have to be detected and evaluated at all times.

Likewise, whether the detected signals actually originate from fingers, that means are wanted, or are caused by external influences such as, for example, moisture or water, dirt, electric fields, electromagnetic radiation or unstable mass concepts. In tactical or gaming applications, algorithms must be able to detect up to 50 touches simultaneously. Usually, however, it is enough to common displays to detect two touches at the same time: for selecting, wiping, rotating, and zooming.