About Touchscreen Technology

Touchscreen technology is the direct manipulation type gesture based technology. Direct manipulation is the ability to manipulate digital world inside a screen without the use of command-line-commands. A device which works on touchscreen technology is coined as Touchscreen.

A touchscreen is an electronic visual display capable of ‘detecting’ and effectively ‘locating’ a touch over its display area. It is sensitive to the touch of a human finger, hand, pointed finger nail and passive objects like stylus. Users can simply move things on the screen, scroll them, make them bigger and many more.

A basic touchscreen has three main components: a touch sensor, a controller, and a software driver. The  touchscreen is an input device, so it  needs to be combined with a display  and a PC or other device to make a  complete touch input system.

1. Touch Sensor

A touch screen sensor is a clear glass panel with a touch responsive surface. The touch sensor/panel is placed over a display screen so that the responsive area of the panel covers the viewable area of the video screen. The sensor generally has an electrical current or signal going through it and touching the screen causes a voltage or signal change. This voltage change is used to determine the location of the touch to the screen.

2. Controller

The controller is a small PC card that connects between the touch sensor and the PC. It takes information from the touch sensor and translates it into information that PC can understand. The controller is usually installed inside the monitor for integrated monitors or it is housed in a plastic case for external touch add-ons/overlays.

3. Software Driver

The driver is a software update for the PC system that allows the touchscreen and computer to work together. It tells the computer's operating system how to interpret the touch event information that is sent from the controller. Most touch screen drivers today are a mouseemulation type driver. This makes touching the screen the same as clicking your mouse at the same location on the screen. This allows the touchscreen to work with existing software and allows new applications to be developed without the need for touchscreen specific programming.

There are three types of touch screen technology:

Resistive: A resistive touch screen panel is coated with a thin metallic electrically conductive and resistive layer that causes a change in the electrical current which is registered as a touch event and sent to the controller for processing. Resistive touch screen panels are generally more affordable but offer only 75% clarity and the layer can be damaged by sharp objects. Resistive touch screen panels are not affected by outside elements such as dust or water.

Advantages of Resistive Touch Screen

1. It has comparatively longer life.
2. It is used in many different ways.
3. It is a very common type of touch screen.
4. It is cheap and so approachable.
5. Due to their durability, they are widely used in commercial zone.

Disadvantages of Resistive Touch Screen

1. It emits less light as 75 % so fails to give sharp image.
2. Its appearance is bulky.

Surface wave: Surface wave 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. Surface wave touch screen panels are the most advanced of the three types, but they can be damaged by outside elements.

Advantages of surface acoustic wave touch screen

1. Because of this wave mechanism versatile action can be done.
2. Being no electric field created, it emits 100% light resultantly quality image received.

Disadvantages of surface acoustic wave touch screen
They tend to have very short life.

1. They are expensive so out of reach of a common man.
2. They can be easily damaged.

Capacitive: A capacitive touch screen panel is coated with a material that stores electrical charges. When the panel is touched, a small amount of charge is drawn to the point of contact. Circuits located at each corner of the panel measure the charge and send the information to the controller for processing. Capacitive touch screen panels must be touched with a finger unlike resistive and surface wave panels that can use fingers and stylus. Capacitive touch screens are not affected by outside elements and have high clarity.

Advantages of Capactive Touch Screen

1. It emits 90% of light ray to make screen clear.
2. It has long life because of the resistivity

Disadvantages of Capactive Touch Screen

1. They are sensitive only for the fingers touch no other object like stylus can be sensed.