Enhanced Optical Touch Input Panel
Original Publication Date: 1985-Sep-01
Included in the Prior Art Database: 2005-Feb-19
Scanning an array of light sources in a two-dimensional (2D) array, bit mapping the display area into triangles, and masking out repeatedly those triangles which contain an opaque object, makes for a simple scheme for detecting multiple objects in the field of the array. Touch panels are useful input devices for use with computer displays, and as digitizing devices in their own right. However, they suffer a limitation in only being able to detect single objects reliably. Fig. 1 shows a row and column of light-emitting diodes (LEDs), opposite a row and column of photodetectors. An object (for example, the tip of a pointing finger) obscures one row and one column optical path. This technique suffers from ambiguities if more than one object is present.