Patent Document ID: 4491923
Application ID: 06347240
Patent Status: 1

Claim One:
1. A method of sensing and identifying of information having an unknown position and orientation within a large interrogation zone, said method comprising: incorporating the information which is to be read on a retroreflective material designed to reflect incident electromagnetic radiation in a concentrated cone surrounding the axes of incidence; irradiating the zone with electromagnetic radiation by a source having a predetermined location with respect to the zone, thereby establishing a known axis of incidence for the radiation from the source; sensing the zone for electromagnetic radiation which is reflected off of objects within the zone; locating the sensing means adjacent the known axis of incidence from the irradiation source, thus receiving radiation originating from the irradiation source and reflected by the retroreflective material, but tending to eliminate radiation from radiation sources which is specularly reflected by areas within the zone; selecting sensed radiation that has a magnitude greater than a predetermined value which is typical for diffuse reflection; and identifying information contained within the selected radiation.