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.
A capacitive touchscreen is a control display that uses the conductive touch of a human finger or a specialized input device for input and control.
Capacitive touchscreen panels must be touched with a finger, a special capacitive pen or a glove. That's because the panel is coated with a material that can store electrical charges. The change in capacitance signals the location of the touch. This differs from resistive and surface wave panels, which can sense input from a finger or stylus.
When a capacitive panel is touched, it draws a small charge to the point of contact, becoming a functional capacitor. The change in the electrostatic field is measured to find the location. In some designs, circuits located at each corner of the panel calculate the charge and send the information to the controller for processing. In multitouchscreens, sensors are arranged in a grid to enable more complex input.
Capacitive touchscreen devices like tablets require a finger, special capacitive pen or glove for input and control.
Resistive touchscreen devices sense the application of pressure, which causes two conductive layers to come into proximity. Capacitive touchscreens don't react to external factors such as temperature, humidity or light, enabling them to function without interference from these variables. They also provide higher levels of clarity, precision and accuracy, even with minimal pressure or touch.
Capacitive touchscreens are found on smartphones, tablets and other mobile devices. These include Android devices and Apple devices like an iPhone and iPad.
Mobile devices like an iPhone, iPad and Android devices use capacitive touchscreens.
A capacitive touchscreen stylus pen is a device used to draw on a touchscreen display. The stylus has two parts: a tip that touches the screen and a base that holds the stylus upright.
When the stylus presses against the screen, it creates a small electrical current between the tip and the screen. This causes the pixels under the tip to light up, enabling a user to draw lines and shapes on the screen.
A tablet with a capacitive touchscreen uses a stylus to write and draw on the screen.
A projected capacitive touchscreen is a touchscreen display technology that uses a matrix of tiny electrodes under the glass surface. This enables thinner displays and better resolution than technologies that use individual wires attached to each pixel.
Projected capacitive technologies can detect touch by calculating the amount of capacitance at each addressable electrode. When a stylus pen or finger approaches the electrode, it alters the capacitance by disturbing the electromagnetic field.
The main advantage of projected capacitive touchscreens is that they don't require a backlight, making them perfect for outdoor use.
The best way to clean a capacitive touchscreen is to use a soft cloth dipped in rubbing alcohol or a mild nonabrasive soap and water solution. Using a dry cloth may damage the surface. However, a microfiber cloth helps remove fingerprints from the surface.
Follow these steps to clean a capacitive touchscreen:
See also: display, interlaced display, non-interlaced display, digital projector, Gorilla Glass, mobile user interface