Touch screen technology

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Thursday 12 April 2012

Does your application require a touch screen display? Unsure what type of touch screen technology to use? Impulse has created a series of resources to help explain the pros, cons and application use for each of the common touch screen technologies.

An overview of touch screen technology

There are five mainstream technologies of touch screen utilised in our industrial LCD displays and Panel PCs. The most common and widely used is Resistive followed by Capacitive, Surface Acoustic Wave, Infrared and the latest Projected Capacitive (PCT).

Each type of touch screen technology has its own distinctive characteristics, some providing advantages and some limitations.

Please see below for a summary of the five key types of touch screen technology available from Impulse. Click the heading of each section to view more detailed explanations of the touch screen technology.

Resistive touch screens

Resistive touch screens offer the lowest cost type of touch screen on the market. Resistive touch screens can accept an input from almost any object, be it a bare finger, a gloved hand or even a pen.

Being so versatile, resistive based touch screens also have some disadvantages. Due to the way resistive touch screens are constructed, they are easier to scratch compared with their glass based counterparts. In addition, resistive touch screens are also affected by extreme temperatures although the latest 8-wire resistive options eliminate this problem.

Learn more about Resistive touch screens

Capacitive touch screens

Capacitive touch screens are commonly found on modern day smart phones and tablet computers. Capacitive touch screens are commonly constructed from glass and are much more resistant against scratches, abrasion and extreme temperatures. Again, capacitive touch screens have their own limitations too. Due to the way the touch sensors work, capacitive touch screens only detect touch from an organic input, such as a bare finger.

Learn more about Capacitive touch screens

SAW touch screens

Surface acoustic wave (SAW) technology uses ultrasonic waves that pass over the touch screen panel. When the panel is touched, a portion of the wave is absorbed. This change in the ultrasonic waves registers the position of the touch event and sends this information to the controller for processing.

Learn more about Surface Acoustic Wave touch screens

Infrared touch screens

An infrared touch screen uses an array of X-Y infrared LED and photodetector pairs around the edges of the screen to detect a disruption in the pattern of LED beams. The LED beams cross each other in vertical and horizontal patterns. When a user touches the screen, the sensors detect an interruption in the X-Y infrared pulses enabling the controller to calculate the touch location.

Learn more about Infrared touch screens

Projected Capacitive touch screens

Traditional touch screen interfaces, such as resistive, capacitive and surface acoustic wave are surface activated. Surface activated means the user’s input needs to make physical contact with the touch interface for it to work.

Projected capacitive (PCT) touch screens do not require physical contact to operate. PCT touch screens are made up of a thin film, covered in a grid of micro-fine sensing wires. A low voltage current is applied to the sensing wires, creating a uniform electro static field.

Learn more about Projected Capacitive touch screens

Associated tags: Capacitive, Impulse, Infrared, LCD, Screen, Tablet

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