Touchscreen Problems (Zombie Finger)

Over the last couple of weeks I have flown from the USA to Britain, then to Italy, and back finally to the USA. I flew on some lovely new Airbus aircraft, but had a constantly recurring problem with the on-board entertainment systems.

The problem is that in the seat above me there is a fantastic touchscreen entertainments system, but my fingers do not work. My son who was sitting next to me has good fingers, he touches the volume section and can turn the sound up or down, but I cannot because the slider does not seem to recognize my body.

So it must be my screen I think, my son leans over and it works perfectly well for him. We swap places, now mine works for him but I still cannot change the volume, this time on a different machine.

It must be me I conclude, but why? Long ago I gave up using anything touchy for this reason. I try licking my hands, warming them up, cleaning the screen but I do not make any progress. So I started looking around the web for some answers to find that I am not the only one, hurrah. There is even a recognized name for the problem in some fields, Zombie Finger!

Touch screens operate in many different ways. At Walker Mobile you can download a free PDF that explains how the different technologies work, but the vast majority of application that we know use one of two approaches. They can be described as Resistive Touch and Projective Capacitance.

Resistive touch is old school analogue. Two surfaces are together, typically one of glass with a thin film over it. You push down on the film and it makes a circuit using a grid of electrical conductors. The system is cheap but being mechanical liable to damage and wear, and it is thick.

Projective Capacitance has no moving parts however, and some of its advantages mean that it is rapidly taking over the market. It is a system that works on capacitance, which is the thing that gives you a shock when you walk over a synthetic carpet and then touch the brass door handle in the hotel that you are staying in.

How iPhone touch screens work.

Again there are two layers, both charged but to a different extent. When you touch the screen some of the charge is released into your finger, and this tiny change can be measured. And here lies a variable, because the nail will not carry a charge, gloves stop the action and so I wonder if even the state of the skin at the end of the fingers might effect usability. Do I type too much? No charge transfer means no volume.

For a fuller explanation of these 2 competing systems see this article, it is short but extremely informative. I would just like to know if anyone else has issues with touch screens, and if so if they have been able to address the issue in some way. As technology advances this interface is becoming the norm, and we wouldn’t want to leave people with particular skin types behind now, would we?