Patent ID: 7920276

Claim:
Apparatus for tracking an object, comprising: a. a multiplicity of optical radiator modules, disposed in an array of known locations adjoining a region in which the object is to move, each module comprising: i. at least one optical emitter, which is structured to emit optical radiation of a respective color, selected from among a first plurality of colors emittable by the modules; ii. and a controller, which is coupled to drive the at least one optical emitter to emit the optical radiation during a respective time slot, selected from among a second plurality of time slots during which the modules may emit the optical radiation, such that the respective color and the respective time slot form a unique combination for each of the modules; b. an optical location unit, structured to be fixed to the object and comprising at least one camera, which is arranged to capture a sequence of electronic images containing at least some of the locations of the modules; c. and a processing unit, which is configured to process the electronic images in the sequence in order to determine, responsively to the colors of the optical radiation emitted by the modules and the time slots in which the optical radiation is emitted, a location of the object.