What is a Touch Screen?

  • Overview


What is a Touch Screen?

A touch screen is a computer display device, with the addition of being an input device. Touch screens are sensitive to the pressure of touch, and rather than using a mouse or keyboard, the user interacts with the screen by directly touching elements on screen with their finger or a stylus pen.

There are four types of touch screens available on the market: resistive, surface wave, infra-red and capacitive. Midshire specialises in the provision of projected capacitive touch and infra-red touch screen technology.

Resistive Touch Screen Technology

Coated with a thin metallic electrically conductive layer, these touch screen panels work by experiencing a change in the electrical current when touched by a user. The change in the electrical current is registered as a touch and sent to the controller for processing. These devices are some of the cheapest on the market, and thus have lower clarity levels.

Surface Wave Touch Screen Technology

Surface wave touch screen technology uses ultrasonic wave technology over the touch panel. Acoustic waves travel across the panel with a series of transducers and reflectors, creating an invisible grid across the screen. The waves are broken when a finger pushes on the touchscreen.

Surface wave touch screen technology panels are one of the most advanced touch screen technologies available, but are susceptible to environmental damage.

What is a Touch ScreenInfra-Red Touch Screen Technology

One of the most useful applications of the infra-red spectrum is in sensing and detection, which is why it is applied to interactive touchscreen technology.

Using LEDs and infra-red light sensors placed on the vertical and horizontal axis of a bezel, the system casts an invisible grid of infra-red beams across the screen. When an object (finger touch, pen or other solid object) touches the screen it interrupts the light beams on the grid, blocking it from the sensor. Infra-red technology is found in the majority of Sharp Touch Screen devices.

Projected Capacitive Touch Screen Technology

This is the most advanced touch screen technology, and can be found in the 40” and 80” Sharp huddle screens. With Projected Capacitive Touch (also known as PCT or PCAP), conductive wires are layered in rows and columns on two parallel sheets of glass, creating a grid. Voltage is then applied sequentially to the rows and columns.

Wherever the screen is touched by a finger the controller identifies the change in capacitance in the grid of wires. PCT screens can recognise multiple touch points. However, ‘noise’ and unintended touch inputs can still be a problem. Because the technology is in the screen, not the surround, these devices have a much thinner bevel.

There is a large range of touch screen devices on the market, with Midshire supplying a wide variety, from touch tables, through to traditional, wall mounted touch screen devices from 32” right through to 90”.