An electronic visual display called a touch screen can detect and locate the presence or location of touch objects within its display area. In the 1960s, the touch screen was already in use. E.A. Johnson created the first touch-driven screen. Johnson in 1965. This technology was not widely known until 1970s, when a University of Kentucky research team accidentally created the resistive touch screen. The University of Toronto developed the first multi-touch screen in 1980. In the 1980s, the first touch screen cell phone was released.
Components
These three components are the core of any touch screen system that uses touch screen technology:
- Touch sensor – The structure and function of touch sensors depends on the type of touch screen being used. It senses any touch that is valid, which can be a finger or a hand.
controller – controller is a small PC card. It indicates the position of the touch in the software. - Software drivers- Software driver allows the software to communicate with the touch screen. These drivers can be developed using the C programming language.
- Different types of touch screens
There are many touch screen options, but these are the most popular:
- Resistive Touch Screen
This is the most common touch screen. When pressed hard enough resistive touch screens bend and resist the touch, hence the name. It has two layers. The outer layer can conduct electricity while the inner layer can conduct it. These layers are separated by small dots called spacers, until the screen touches. The two layers are constantly being energized by an electrical current. When a finger touches the screen, the electrical current changes and the layers become pressed together. Software on the device detects a change in that spot and performs its function accordingly. This type is durable and reliable. This type has some drawbacks. For example, it can be difficult to read because of the multiple layers. Also, you can’t zoom in to see better as they can only handle one touch at a given time.
Capacitive Touch Screen
These touch screens are made from copper or indium tinoxide. Both keep the electrical charges in thin wires. When the capacitive screen comes in contact with any object that has a charge, it changes the electric current. This includes our skin.
Two types of capacitive screen are available:
Projective Utilizes a tight grid with special sensor chips.
- Surface: uses tiny sensors in the corner and a thin, paper-thin film evenly spread across the screen.
A small amount of electricity is transferred back to the finger when a finger touches the screen. The result is a complete circuit that causes a voltage drop at a specific location. Software analyzes the location of the voltage drop, and then follows the command accordingly.
Additional touch screens can be classified into many other types, some of which are listed below:
Infrared:
Their display emits infrared light and forms webs or grids directly in front of it. A few infrared radiations are interrupted when someone touches the screen. This causes a reaction. A microchip can detect the exact location of the interruption and will perform the job accordingly.
Surface Acoustic Wave Technology
The technology uses sound to detect touch. Ultrasonic sound waves are created at the edges of the screen and reflect back and forth across the screen. These ultrasonic sounds can’t be heard by the human ear because they are too high in pitch. Touching the screen causes the sound waves to be disturbed and the finger absorbs some of the energy. This is how the microchip controller detects when the screen has been hit.
