“Touch Screen on the go…”

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“Touch Screen on the go…”

Overview

I use to wonder when I first know about touchscreen and see it in action. I was amazed with its working principle and was more curious about its features and the way it can lead the tech products in the future.

Touchscreen

A touchscreen is an electronic visual display that can detect the presence and location of a touch within the display area. In general it refers to touching the display of the device with a finger or hand. Touchscreens can also sense other passive objects, such as a stylus. Touchscreen is common in devices such as all-in-one computers, tablet computers, and smartphones.

First Touchscreen Computer

The HP-150 from 1983 was one of the world's earliest commercial touchscreen computers. It did not have a touchscreen instead, it had a 9" Sony Cathode Ray Tube (CRT) surrounded by infrared transmitters and receivers, which detected the position of any non-transparent object on the screen.

Technologies

There are a variety of touchscreen technologies:

1 Resistive
2 Surface acoustic wave
3 Capacitive
- 3.1 Surface capacitance
- 3.2 Projected capacitance
  - 3.2.1 Mutual capacitance
  - 3.2.2 Self-capacitance
4 Infrared
5 Optical imaging
6 Dispersive signal technology
7 Acoustic pulse recognition

Construction

There are several ways to build a touchscreen. The main thing is to recognize one or more fingers touching a display, to interpret the command that this represents, and to communicate the command to the appropriate application.

Among the above techniques, the Capacitive or Resistive technology is the most used which consists of four layers:

Top polyester coated with a transparent metallic conductive coating on the bottom
Adhesive spacer
Glass layer coated with a transparent metallic conductive coating on the top
Adhesive layer on the backside of the glass for mounting.

Parts of Touchscreen

Touchscreen has three main parts: Touchscreen Sensor, Controller and Driver Software.

Touchscreen Sensor

A Touchscreen sensor is a touch responsive surface made up of glass panel. It is fitted over the monitor's screen so that viewable area of the display screen is covered with the responsive area of the glass panel. There is an electrical current or signal going through the sensor and touching the screen makes a change in voltage or signal. This voltage change is used to determine the location of the touch to the screen.

Controller

The controller is an interface between touch sensor and the PC. It is a small PC card which takes information from the touch sensor and translates it into information that the PC can understand.The controller sends the touch event information to PC. Controllers that can be connected to Serial / COM or USB port are available.

Software Driver

The software driver for the touch screens makes it compatible to work with computer. The controller send the touch event information to the driver and the driver further tells the operating system how to interpret touch event information. Touchscreens drivers are like mouse drivers, so touching the screen is similar as clicking a mouse. As these are quite similar actions, the touchscreen can work with existing software.