Patent ID: 9524061
Filing Date: 2016-12-20
CPC Classification: G06F

Claim Text:
1. A touch sensitive image display device, the device comprising: an image projector to project a displayed image onto a surface in front of the device; a touch sensor light source to project a plane of light above said displayed image; a camera directed to capture a touch sense image from a region including at least a portion of said plane of light, said touch sense image comprising light scattered from said plane of light by an object approaching said displayed image; and a signal processor coupled to said camera, to process a said touch sense image from said camera to identify a location of said object relative to said displayed image; wherein: said touch sensor light source is on-off modulated; said signal processor is configured to determine two difference images, a first difference image between said touch sense image captured when said touch sensor light source is on and a preceding said image captured when said touch sensor light source is off, and a second difference image between said touch sense image captured when said touch sensor light source is on and a following said image captured when said touch sensor light source is off, and to compensate, for a level of ambient light in said captured touch sense image captured when said touch sensor light source is on, by selecting data, for processing to identify said location of said object, dependent on said two difference images, and said selecting comprises using one of said two difference images as a mask for the other of said two difference images.