Today’s Wonder of the Day was inspired by Cohen. Cohen Wonders, “How does touch screen work?” Thanks for WONDERing with us, Cohen!

From mall kiosks to smartphones to tablet computers, touch screens are everywhere you look these days. As technology advances, keyboards and mice are quickly becoming a thing of the past. Why be burdened with cords when you can have what you want with just a touch?

Touch screens are electronic visual displays that allow a user to interact directly with what is displayed on the screen, rather than using a pointing device, such as a mouse. Touch screens are designed to respond to the touch of a finger, although an object — like a stylus — can also be used.

Touch screens are used in all sorts of modern electronic devices, including personal digital assistants (PDAs), satellite navigation systems and video games. Their popularity has surged recently, but the idea for the touch screen goes back several decades.

The idea for the touch screen was first developed by E.A. Johnson at the Royal Radar Establishment in England. His idea was first described in a short article published in 1965.

Given the many different types of devices that use touch screens, it's no surprise that there are several different types of touch screens. Each type of touch screen works a little differently from the others.

Resistive touch screen systems use two thin metallic layers separated by spacers. An electrical current runs through the two layers. When the screen is touched, the two layers make contact in the exact spot where the screen is touched. This contact creates a change in the electrical field, which a device's computer operating system can understand.

Capacitive touch screen systems feature a special layer that stores an electrical charge. When the screen is touched, some of the electrical charge is transferred to the user. This decreases the charge on the capacitive layer. The device's computer operating system can determine from this change in electrical charge where the screen was touched.

For a capacitive system to work, some of the electrical charge must be able to be transmitted to the user. This is why capacitive touch screens may not work properly if you wear gloves that block the transmission of the electrical charge.

Capacitive systems are newer and tend to be more popular than resistive systems, because they transmit more light and provide a clearer picture. Of course, capacitive systems also tend to be more expensive than resistive systems, too.

Surface acoustic wave touch screen systems use transducers and reflectors to measure changes in the reflection of ultrasonic waves caused when the screen is touched. These systems are the most advanced and offer the clearest picture possible. Unfortunately, they're also extremely expensive.

When touch screens first became popular, they could only sense one point of contact at a time. Technology has advanced greatly in recent years, though. Today, many touch screen devices feature multi-touch technology. This technology allows a touch screen device to interpret multiple points of contact simultaneously.

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