System and method for contactless touch screen

摘要

A touch screen that employs a lens-less linear IR sensor array and an IR light source from a single location at the periphery of the screen to illuminate one or more objects proximate to the screen surface and detect light reflected from such objects. The sensor array is paired with a proximal grid-like barrier/reflector to create Moiré patterns on the sensor array. Digital signal processing converts such patterns into discrete Fourier transforms. The peaks of the lower order discrete Fourier spectrum as well as the complex phases of the lower order peaks can be used to determine the locations of the objects proximal to the screen accurately. A small number of pressure or surface acoustic sensors at the periphery of the screen are utilized to improve positioning reliability by providing redundant positioning information and registering physical contacts with the screen.