The Magic of the Touchscreen

Have you ever wondered how a touchscreen works? Why does the display on your smartphone change when you touch it? Is it magic? No, it’s science. In this article, we’re going to dive into a little history and explain the different types of touchscreens.

Despite appearing as modern technology, the birth of touchscreens can be traced back to 1965 when Eric A. Johnson published an article about his invention of the capacitive touchscreen. This design works by measuring the electrical charge of a layer of glass, a good electrical insulator. Your fingers carry an electrical charge, and when you touch the screen, you change the electrical charge of the screen. The computer calculates the change and location and can use that information to respond to the touch. Later, the capacitive touchscreen was improved so that you can touch the screen in multiple places at once. You are probably most familiar with the capacitive touchscreen since it is the type that modern smartphones use. The lack of electrical charge is why using a plastic stylus or a regular gloved finger doesn’t work.

Fun Fact: As of 2020, there are about 4.78 billion mobile phone users, 3.5 billion of them being smartphones!

The next type is the resistive touchscreen, invented in the 1970s by Dr. G. Samuel Hurst. It also deals with electrical current, however, it does not need the electrical current from outside sources. There are two layers: a conductive layer and a resistive layer. When you push the two layers together, they create a change in the electrical field that the computer can detect. Although resistive touchscreens provide low clarity, they are cheaper, making them more affordable for other devices. In addition, a plastic stylus or regular gloved hand can be used since the design relies on outside pressure rather than outside electrical current. Some capacitive touchscreens can be used with a special stylus or a specific type of gloves.

An example of this is found at the checkout of a supermarket. When using a credit or debit card for payment, you have to swipe your card or insert your card in a small device next to the cashier. Sometimes, you have to write your signature and/or accept the amount for payment on the device. This device often comes with a stylus that you can use to write your signature and click “OK.” If you think about it, the screen is resistive. Sometimes, if the device doesn’t register the stylus’s or your finger’s touch, you have to press harder, pushing those two layers together, unlike touching your smartphone. Nintendo DS screens and ATM screens are other examples of resistive touchscreens.

In the 60s and 70s, people were looking to downsize computers; the touchscreen aided in that objective. The first consumer touchscreen products were known as “personal computers.” Soon, a new touchscreen system was born. Devices that used this system would emit infrared beams and calculate where they were interrupted. Unfortunately, the first device that used this system was flawed in a couple of ways: dust would settle in the infrared holes and the design wasn’t too user-friendly. As a result, this system was not very popular.

The popularity of touchscreens skyrocketed after Apple’s release of the first iPhone. This invention provided everyday users with a convenient way for communication, as well as entertainment. Its multi-touch capability, new in the consumer market, allowed a variety of functions but was only possible through the more expensive capacitive touchscreen. Naturally, the release of the iPhone prompted the innovation of the iPad, a tablet that provided a much larger capacitive screen, which was useful for businesses. Other companies have also released various smartphone and tablet designs; some desktop computers have capacitive touchscreens as well.

The system that provides high clarity (at least higher than resistive and capacitive touchscreens) is the surface acoustic wave system. Unlike the other designs, this design relies on sound waves. The concept is similar to the infrared system, but instead of infrared waves, the design detects the locations of interruptions in sound waves. Despite its ability to present detailed graphics, this system is not used as often due to its high cost (even higher than capacitive touchscreens).

Technology is constantly improving, and there are many ideas involving touchscreens in the future. Touchscreens are something many people take for granted, especially the younger generations that grew up with the technology, but not many people understand the science behind it or even the importance. Touchscreens boost efficiency in many areas, particularly communication, and it makes devices easier to use. I hope you learned something new! Keep a lookout for the next post!