Working of Touchscreen

GS Paper III Science and Technology

Context: Recently, Volkswagen brought back physical buttons after complaints about its touchscreen.

About Touchscreen

Touchscreen is an electronic visual display capable of ‘detecting’ and ‘locating’ a touch over its display area.
It combines two functions i.e. to receive inputs for a computer and to display the output.
Examples: Smartphones, ATM machines, various household appliances (including TVs and refrigerators), e-readers, billing systems, and electronic voting machines.

Invention Journey

1965: The touchscreen was invented by E.A. Johnson to overcome the limitations in man-machine communications.
1970: G. Samuel Hurst invented the resistive touchscreen.
1982: Nimish Mehta developed a touchscreen that could sense two touches at the same time.
1983: Myron Krueger reported a way to capture different hand gestures as actions on a screen.
1984: Bob Boie developed the first transparent (capacitive) multitouch interface.

The two most common types of touchscreens are capacitive and resistive which are based on the phenomenon of conduction and resistance respectively.
Other touchscreen technologies are based on optical inputs and acoustic waves.

Composition: There are two conducting layers and each layer consists of strips of conducting material.
- In one, the strips run left to right, and in the other from top to bottom.
Working: When two strips cross over each other, they form a capacitor, and is used to measure where a finger has touched the screen.
- It is significant in detecting multiple simultaneous touches.
Use: It is used in smartphones with the mutual capacitance architecture.

About: It uses the property of resistance. Resistance is a measure of the opposition to current flow in an electrical circuit.
Composition: There are two sheets, both are conductors which are separated by a small gap.
Working:
- Flow of Current using Sensation Mechanism: When a finger touches one sheet, it moves it at that point to touch the underlying sheet and allows a current to pass.
- Sensing by the Sensors: Sensors use this flow of current and with the help of processor, determine the point of touch.
Significance: Resistive touchscreens are cheaper to make and require less power to operate.
Concern: It emits less light and its appearance is bulky.