Optical Imaging Touch

A wide variety of LCDs and all-in-one PCs have been introduced since Windows began supporting multi-touch operations.

Optical imaging systems consist of infrared LEDs and optical sensors in the upper left and right sides of the screen. Retroreflective sheets are also used along the left, right, and bottom of the screen. The optical sensors detect the shadow of a finger or other object used to touch the screen, and the shadow’s coordinates are calculated through triangulation.

These devices offer high transmittance and durability as well as touch operations with gloves on and multi-touch support. The structure is also simple, making it easy to increase screen sizes.

However, the bezels must be wide enough to fit the light emitters and detectors along the outside of the screen display area, and devices are susceptible to false detections caused by outside lights and shadows.