How Do Touchscreens Work?

Dr. Samuel C. Hurst invented the touchscreen in 1971. We found plenty of information about how it works — and most of it reads to us liberal-arts types like the manual for the holodeck. Wikipedia, Howstuffworks.com, and this column from The Hindu offer explanations relatively accessible to the layperson. But let’s break it down:

A touchscreen’s main components are a touch sensor, controller, and software driver, combined with a display and computer processor. The sensor is a touch-responsive glass panel, usually employing one of three technologies: resistive, surface wave, or capacitive.

Resistive systems send an electrical current that is altered when it passes through an electrically conductive layer. The change in the current is then recorded as a “touch event.” Surface wave systems generate ultrasonic waves. When the screen is touched, a portion of the wave is absorbed, and a receiving transducer detects the alteration. Capacitive sensor panels are coated with a material that stores electrical charge. When the monitor is touched, a portion of the charge is transferred to the user, decreasing the panel’s capacitive layer. Electronic circuits then measure the ensuing alteration and calculate where the touch event occurred.

SEX! (Just want to see who’s still paying attention.)

In all these systems, information passes from the sensor to the controller, which translates it into computer language. The software driver then tells the computer’s operating system how to interpret the information the controller sends, and voilà…the ATM spits out another notice of “insufficient funds.”