US 8,274,495 B2Granted

System and method for contactless touch screen

AssigneeGeneral Display, Ltd.

InventorYee Chun Lee

Life of this patent

Estimating the term…

Loading patent…

Abstract

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.

Claims16

Dependent claims

A device comprising:

a display screen;
an infrared light source at a periphery of the screen adapted to illuminate objects proximate to the screen surface;
an infrared sensor array adapted to detect light reflected from the objects proximate to the screen surface;
a proximal barrier adapted to create Moiré patterns on the infrared sensor array using infrared light reflected from the objects proximate to the screen surface;
a processing module adapted to convert the Moiré patterns into a discrete Fourier spectrum, wherein peaks of a lower order discrete Fourier spectrum and complex phases of the peaks of the lower order discrete Fourier spectrum are used to determine the location of the objects proximal to the screen;
and
a plurality of strain gauges at the periphery of the display screen adapted to detect physical contact of the objects with the display screen,
wherein the peaks in the lower order part of the spectrum provide radial positioning information for objects proximate to the screen surface, and the complex phases of the lower order Fourier spectrum peaks provide azimuthal positioning information for such objects.

5 more elements

Dependencies are inferred from the claim text.