A touch screen is an electronic visual display that can detect the presence and location of a touch (usually by a finger or hand) within the display area.
The touch screen already appeared way back in the 1960s. The very first touch-driven screen was created by E.A. Johnson in 1965. This technology didn’t seek much attention until the 1970s when the resistive touch screen was accidentally invented by a research team in the U.S. at the University of Kentucky. On further development, the first multi-touch display was invented in the 1980s at the University of Toronto. First touch screen cell phones came out in the 1980s.
Components
Any system with touch screen technology has these three main components which make the touch screen work:
- Touch sensor – The structure of touch sensors depend on the type of touch screen we’re using. Its work is to sense any valid touch, valid touch meaning by a finger or hand.
- Controller – Controller is a small pc card. It gives the location of the touch to the software of the device.
- Software drivers – Software drivers allow the software to work in cooperation with the touch screen. These drivers are developed using the C programming language.
Types of Touch Screens
There are many types of touch screens but the two most commonly used are as follows :-
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Resistive Touch Screen:
It is the simplest and most commonly used touch screen. Resistive touch screens when pressed hard enough, bend, and resists the touch hence, the name. It consists of two layers that can conduct electricity, the outer layer is resistive and the inner layer is conductive. These two layers are separated by tiny dots called spacers until the screen is touched. An electrical current constantly runs through the two layers, when all of a sudden a finger hits the screen, the two layers get pressed together and the electrical current changes. The device’s software feels a change in this particular spot and does its work means that it fulfills the function that corresponds to that place. Some pros of this type are that it is reliable and durable. There are some cons of this type that is it’s pretty hard to read the screen due to their multiple layers, the more light falls on the display the harder it is to read, also can’t zoom in to see more clearly because they can handle only one touch at a time. -
Capacitive Touch Screen:
These touch screens are made of indium tin oxide or copper, both of them keep electrical charges in very thin wires. The capacitive screen changes the electric current when it comes into contact with anything that holds a charge that means even our skin. There are two types of capacitive screens :- Projective: Uses a tight grid of special sensor chips.
- Surface: uses small sensors in the corner as well as a paper-thin film evenly distributed over the screen.
As soon as a finger comes in contact with the screen, it transfers a small amount of electrical charge back to the finger. As a result, there forms a complete circuit which leads to a voltage drop in a particular place. The software analyses the location of the voltage drop and follows the command accordingly.
Further touch screens are classified into many more types some of them are given below :
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Infrared:
Their display shines infrared light in the form of web or grids in front of the screen. As soon as someone touches the screen, a couple of infrared rays gets interrupted and gives a reaction. By analyzing the location of the interruption, a microchip will do the job accordingly. -
Surface Acoustic Wave Technology:
Their technology uses sound to detect any touch. The screen creates ultrasonic sound waves at its edges, and they get reflected back and forth all over the screen. These ultrasonic sounds are too high pitched to be heard by the human ear. As soon as someone touches the screen, not only the sound waves get disturbed but the finger also absorbs some wave’s energy. This is how the microchip controller understands where the screen is hit.
Advantages
- Reduces error while accessing something.
- Provides easy and fast access to any file.
- Reduces the need of extra input devices like keyboard, mouse, etc. hence saves energy.
- Provides good security.
Disadvantages
- They are not suitable to store very large amount of data.
- Installing a large no. of touch screen devices can be pretty expensive hence not cost effective.