What Is A Touchscreen?

Date First Published: 16th September 2023

Topic: Computer Systems

Subtopic: Computer Hardware

Article Type: Computer Terms & Definitions

Difficulty Level: 3/10

Learn about what a touchscreen is in this article.

A touchscreen is an electronic display screen that allows users to interact with it by touching it with their fingers or a stylus pen instead of a pointing device, like a mouse. This makes them more intuitive and feel more natural. Mobile devices, like smartphones and tablets most commonly use touchscreens and they are often found at the checkout counter at a grocery store. Also, laptops and all-in-one computers can have a touchscreen, but not all computers and laptops come with one to reduce costs.

Touchscreens often use a virtual, on-screen keyboard to allow users to type letters, numbers, and symbols with their fingers. In addition, smartphones and tablets often have voice recognition for inputting information into the device.

Touchscreen Technologies

The four most common technologies that touchscreens use to enable interaction with the display screen are:

• Capacitive - A capacitive touchscreen panel is coated with a material that stores electrical charges. When the display panel is touched, it draws a small amount of charge to the contact point. Circuits located at each corner of the panel measure the charge and send the information to the controller for processing. Below the touchscreen layer is the LCD layer, which is used for the actual display.
• Infrared - Infrared touchscreens use a series of infrared beams, which are transmitted by LEDs with a phototransistor receiving end. The infrared beam is blocked when a finger or tool is used near the display, providing the device with input on the location of the finger or tool.
• Resistive - A resistive touchscreen panel is coated with a thin metallic electrically conductive and resistive layer. When touched, it causes a change in the electrical current, which is registered as a touch event and sent to the controller for processing. The resistive layer detects the pressure of the finger or another object. Although it is cheaper than capacitive, it can be damaged by sharp objects touching the screen.
• Surface acoustic wave - Ultrasonic waves are used that pass over the touchscreen panel. When the panel is touched, a portion of the wave is absorbed. The change in the ultrasonic wave registers the position of the touch event and this information is sent to the controller for processing. This is the most advanced technology, but can be damaged by outside elements.

Advancements

Early touchscreens could only detect a single point of input at a time. Now, modern touchscreens support multi-touch input. This technology enables multiple finger motions to be detected at once by the display screen. For example, most touchscreen devices allow zooming in or out by spreading two fingers apart or pinching them together and some touchscreen devices allow images to be rotated by twisting three fingers in a clockwise or anticlockwise direction. Technological advancements have made touchscreens easier to use and more natural than they originally were.

Is A Touchscreen An Input Or An Output Device?

A touchscreen is both an input and output device as it takes input from the person operating the device by them touching it with their fingers or a stylus pen and also displays output from the computer.

Spelling

This term can be spelt as "touchscreen" or "touch screen" when used as a noun. Both forms are acceptable in writing, but "touchscreen" is more commonly used and recommended by more style guides. If used as an adjective, the term can be hyphenated (e.g. "touch-screen devices.")

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