Capacitive Touch Panel Heat Detection Myth Busted

Many people believe that there are certain touchscreens that detect heat. For example, an iPhone’s touch screen will detect interactions with a finger but will not detect activity from a stylus pen. However, it’s not heat which these kinds of touch screens detect but it is the conductibility of an object; something that capacitive touch panels specialize in.

Capacitive touch panels come in two types—surface capacitive and projected capacitive. Projected capacitive screens are the second most widely used sensing technology for touch-sensitive devices. These touch screens contain a layer that stores electrical charge which transfers to the user as actions through the touchscreen are performed.

As the electrical charge is transferred to the user, sensors calculate the relative differences in charge and thus detects the finger’s location on the screen. The screen detects conductive material like your finger and not nonconductive material such as stylus pens and gloves.

One advantage of capacitive touch panels is that they transmit more light compared to resistive touch panel screens. This allows them to produce a clearer image than the resistive system. Additionally, although more expensive than the resistive system, capacitive touchscreens are newer and more common. Plus, they provide excellent finger touch detection and better durability.

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The Past and Future of Touch Screen Technology

You see it in almost every piece of commercial hardware nowadays. From handhelds to 20-inch display monitors, touch screen technology is as integrated in daily life as the Internet. While it may seem like a modern innovation, the touch screen isn’t exactly a new technology; it was invented in 1965 by a British scientist named E.A. Johnson.

His work was somewhat crude and can only process one touch at a time, but Johnson’s capacitive touch screen, which is coated with an indium tin oxide (ITO) capacitor, would form the basis of today’s touch display devices. This technology was further developed by Dr. G. Samuel Hurst and his team from the University of Kentucky during the 70’s. Their resistive touch screens rely on sensors which detect movement in plane coordinates. This layout would then be used by the PLATO IV in 1971, the first-ever touch screen computer.

Today, it’s not just computers that use touch screen technology—it can also be found in TVs, cellphones, and other devices. While ITO capacitors are still used by current generation touch screens, some scientists are looking at incorporating more advanced nanowires to build smaller and “trendier” touch screens. Bendy screens, for instance, may seem like a gimmick for most people, but they may actually become a necessity to make future generation touch screens smaller and more compact. 

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