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Demystifying Tech: Touchscreens

Demystifying Tech is a new weekly series in which TechnoBuffalo’s staff deciphers the cryptic technology terms that are thrown around everyday. By attaining a higher knowledge of the specifications backing the latest gadgets, one is able to make educated decisions and construct substantial opinions about controversial and complex topics.

Today, we’ll be briefly visiting the history of touchscreen devices before diving into the modern day technology driving forward touch-enabled interfaces.

A Brief History of Touchscreens

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Contrary to popular belief, the first touch sensor was actually a capacitive panel developed by a British inventor named E.A. Johnson. His work was published officially in 1968, providing full photographs and diagrams. It is because of Johnson’s diagrams that Dr. Sam Hurst, the founder of Elographics and a professor at the University of Kentucky, was able to develop the first resistive touch panel. Patented by the university shortly after its invention in 1971, Hurst named the device the Elograph. Though the screen was not transparent like many modern screens, it was a significant milestone in the evolution of touch screens.

The first true transparent touchscreen was created by Dr. Hurst three years later, developing a five-wire resistive technology, which has given rise to the most popular type of touchscreen used today. This panel was implemented in computer-assisted learning programs in 1975 as a part of the PLATO project. After they captured the attention of a large market, they began to become more and more prevalent in everyday life.

During the early 1980s, the Fairlight CMI was created to act as a high-end musical sampling workstation that utilized pen technology, allowing users to allocate and manipulate musical samples. The world’s earliest touchscreen computer came in 1983 with the HP-150, which used infrared transmitters and receivers mounted around a cathode ray tube monitor which detected the position of any opaque object on the screen.

iPhone 4The vast majority of early touchscreens would easily become flustered with multitouch gestures, but that has changed in recent years with the commercialization of capacitive screens. The popularity of smartphones and tablets have driven the demand and acceptance of touchscreens, giving users an extremely intuitive way to interact with their content. Throughout history, the touchscreen sensor and firmware have been made available by system integrators as opposed to monopolization in one manufacturer.

Innumerable devices are currently on the market that utilize the many forms of touch interaction and there is no doubt that the number of gadgets with touchscreens will only increase in the future.

Touchscreen Technologies

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Every touchscreen is comprised of four layers: polyester coated with a metallic conductor, an adhesive spacer, a glass layer, and an adhesive backing. Beyond that, there are many different technologies that dictate user interaction by touch gestures.

1. Resistive

What is particularly notable about resistive touchscreens is the two thin, conductive layers that are separated by only a narrow gap. When these two layers are pressed against one another, an effect caused by pressure, the panel simulates a voltage divider with connected outputs. This current’s information is relayed to the device’s processor, which analyzes user interaction and produces the proper programmed response.

2. Capacitive

Consisting of an insulator and transparent conductor, a capacitive touch panel relies on a constant electrostatic field to analyze environmental variables. Considering the fact that the human body is a conductor, user input disrupts the  measurement as a change in capacitance. The location of this change is sent to the controller for processing. Capacitive touchscreens have reached a consumer market in recent years with the widespread release of devices such as the iPhone and iPad.

3. Infrared

An infrared touch panel uses an array of X-Y infrared LED and photodetector pairs that can detect a disruption on the screen. One of the major advantages of infrared touch detection is that it can sense essentially any input including a finger, gloved finger, stylus or pen. The optical clarity of these type of systems is much better than that of comparable panels because it does not require any extra layers for touch detection.

The widespread adoption of capacitive touchscreens has come as a result of their increased precision in everyday circumstances alongside the gradual commercialization of the technology. Resistive touchscreens hold the biggest share of the market, but lack the accuracy of their capacitive brethren. However, with the innovation of resistive multitouch, resistive panels, which are relatively inexpensive to produce, have become more competitive.

What do you, smartphone and tablet users, think? Is there a specific standard that you prefer? Sound off in the comments below.


Jack McGrath

Rooted in his childhood obsession with dismantling and reassembling gizmos and gadgets around the house, Jack McGrath's knowledge of programming,...

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