From desk tops to smart phones, passive screens are on the way out. Almost everyone, it seems, is enamored of touch screen technology. That is not so surprising considering its advantages over the old view only screens. It seems like touch screen technology is here to stay, though not many people truly understand how they work. The convenience offered by the use of touch screen technology has made it an indispensable feature of smart devices.
A touch screen is an input device layered on top of a visual display usually of a computer or a smart device. Through various technologies, touch screens enable the user to interact with what is displayed on the screen instead of having to use a mouse, touchpad or keyboard. With a few deft touches, such screens will display an onscreen version of the keyboard for data input. Though the technology started with the use touch screens able to process only one touch at a time, multiple touch of multi touch screens are getting more common.
There are four main types of technologies used for touch screens, which are:
Resistive technology: Touch screens using this technology have two layers with electrical conductors arranged on a grid. The layers are separated by space so that the conductors only touch at the point where finger pressure is applied. The point where conductors meet provides horizontal and vertical axis grid locations, which is then translated to a data input or command. Because the outer layer has to give or bend a little for the conductor grids to meet, conductors can break. Most resistive screens can only handle a single touch at a time.
Capacitive technology: Capacitive touch screens have an overlay made of glass coated with capacitive material (capable of storing a charge. Circuits at the corners of the overlay continuously measure the capacitance, which changes slightly at the point or points where it is touched by a human hand. Changes in capacitance at the point of touch is then converted first to x and y coordinates, and from there to instructions or data input. While they are resistant to scratching, touches by non-conductors, including most types of gloves, will not register.
Infrared technology: Touch screens using infrared technology have pairs of light emitting diodes (LED’s) and phototransistor detectors arranged on its sides. These produce a grid of infrared light which is broken at points of touch. The photocells detect the x and y locations at points of touch and translate these to instructions or data input. While this technology is very robust and reliable, setting a solid object on top of the screen causes problems.
Surface Acoustic Wave (SAW) technology: This type of touch screens uses sound waves inaudible to humans. The sounds are transmitted to detect vertical and horizontal point. Touch causes the sound waves to be broken which allows horizontal and vertical receiver arrays to determine location and translate these to input. The technology is very reliable, but also cost a bit more.
Each type of touch screen technology has its own pros and cons; something members of organizations like the Computer and Communications Industry Association are well aware of. Some are more affordable, some are more robust, while others can handle multiple simultaneous touches. Compare and find the technology that fits your needs best.