Touchscreens or Human Machine Interface (HMI)

Touchscreens or Human Machine Interface (HMI)

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Call it an effort of human mind or a miracle from human heart. But this is all happening with technology. We land in an era where everything that can be possibly thought, can also be practically put into. And that too quite reasonably..!! Just move the hand or walk your fingers over a thing and it works. Yes, it is the interactive gesture based technology I am talking about.

touch screen display 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.

Hailing the History..!!

The first ever touchscreen was developed by E.A Johnson at the Royal Radar Establishment, Malvern, UK in the late 1960s. Evidently, the first touchscreen was a capacitive type; the one widely used in smart phones nowadays. In 1971, a milestone to touchscreen technology was developed by Doctor Sam Hurst, an instructor at the University of Kentucky Research   Foundation. It was a touch sensor named ‘Elograph’. Later in 1974, Hurst in association with his company Elographics came up with the first real touchscreen featuring a transparent surface. In 1977, Elographics developed and patented a resistive touchscreen technology, one of the most popular touchscreen technologies in use today.

Ever since then, touchscreen displays are widely used in computers, user interactive machines, public kiosks, point of sale applications, gaming consoles, PDAs, phone, tablets, etc.

Types of Touchscreen Technology

Let us now give an engineer’s eye to this revolutionary technology. A touchscreen is a 2 dimensional sensing device made of 2 sheets of material separated by spacers. There are four main touchscreen technologies:

1)      Resistive

2)      Capacitive

3)      Surface Acoustic Wave

4)      Infrared

  1. Resistive Touchscreen Technology

The resistive touchscreen consists of a flexible top layer made of Polyethylene (PET) and a rigid bottom layer made of glass. Both the layers are coated with a conducting compound called Indium Tin Oxide (ITO) and then spaced with spacers. While the monitor is operational, an electric current flows between the two layers. When a touch is made, the flexible screen presses down and touches the bottom layer. A change in electrical current is hence detected and the coordinates of the point of touch is calculated by the controller and parsed into readable signals for the operating system to react accordingly.

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