CAPACITIVE METHOD AND APPARATUS FOR ACCESSING INFORMATION ENCODED BY A DIFFERENTIALLY CONDUCTIVE PATTERN

摘要

Barcode patterns or other meaningful patterns are printed with a differentially conductive ink. A sensor incorporating a plurality of capacitive couplings distinguishes features of the patterns by comparative measurements that are largely independent of variations between the sensor and the patterns affecting all of the couplings. The patterns can be distinguished despite being hidden from view, such as inside sealed envelopes.