How touchscreens work

Touchscreen technology – how did we live without it? From smartphones and tablets to self-service tills, ATMS, information kiosks and industrial and medical equipment, touchscreens have transformed how we perform many routine tasks.

Put simply, touch technology makes our lives easier but have you ever wondered how touchscreens work?

In its most basic form a touchscreen is a piece of hardware that replicates a mouse on a PC when running applications. Unlike a mouse and keyboard it offers a more intuitive interface for users, after all from an early age we have all known how to point at something and say; “I want that!” In recent years the market has changed with the ability to do more than single point touching (comes at a price), with multi-touch technologies supporting swiping, pinching and zooming gestures emulated on a monitor screen.

Typically, touchscreens can be broken down into three basic components:

The touch sensor: A glass or plastic layer with a touch responsive surface that is placed in front of a display (Infra-Red technologies being slightly different). Sensors generally have a current, light or field of some sort running through them so a touch on the screen is detected as a change in voltage, light, capacitance or field strength.

The controller: The hardware that converts these changes from the sensor into useful data such as co-ordinates that a computer or other device can receive.

A driver: Software application that reads the information from the controller and firstly interprets whether the touch is valid or not and subsequently the details of the touch allowing the device to respond accordingly.

These three things together is what we mean when we talk about touch technology.

Resistive touch technology was one of the first touch overlay systems to be developed in the late 60s/early 70s. Since then there have been huge advances in the technology and today around 20 different touch technologies exist worldwide, although in mainstream applications only around five single touch and two or three multi-touch systems are used in large volumes – Resistive, Surface Acoustic Wave (SAW), Infrared, Surface Capacitive and Projected Capacitive (PCT or Pcap).

Kevin Lee is the Director EMEA Sales/Support at Baanto International Limited.

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