Promethean Limited

John Andrew

Euan Christopher Smith

Paul Richard Routley

Gareth John McCaughan

Adrian James Cable

Peter William Tudor Mash

We describe a touch sensitive image display device including: an image projector to project a displayed image onto a surface; a touch sensor light source to project a plane of light above the displayed image; a camera to capture a touch sense image from light scattered from the plane of light by an approaching object; and a signal processor to process the touch sense image to identify a location of the object. The touch sensor light source is amplitude modulated, and signal processor is further configured to process a plurality of the touch sense images captured when the touch sensor light source is off to compensate for ambient light in a touch sense image captured when the touch sensor light source is on.

Touch-sensitive display devices

A touch sensitive device, the device comprising: a touch sensor light source to project a plane of light above a surface; 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 a plurality of said objects simultaneously approaching or touching said surface; a signal processor coupled to said camera, to process a said touch sense image from said camera to identify a lateral location of each of said objects; and an output object position output, to provide output object positions for said plurality of objects; and wherein said signal processor is further configured to: input a succession of said touch sense images; process each said touch sense image to identify a plurality of candidate object touch positions; and filter said candidate object touch positions from said successive touch sense images to link said candidate object touch positions to previously identified output object positions for said plurality of objects; and update said previously identified output object positions using said linked candidate object touch positions.

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Cambridgeshire, United Kingdom

John Andrew