Patent ID: 7490772
Filing Date: 2009-02-17
Classification: G06K

Abstract:
1. A method, comprising: capacitively coupling a reader to a first code comprising code elements, wherein a first part of the code elements is substantially conductive and a conductivity of a second part of the code elements is substantially different from a conductivity of the first part of the code elements; forming with the reader a signal that is proportional to a capacitance between the first code and the reader, wherein a level of the signal varies according to the conductivity of the code elements; detecting edges of the signal; determining a width of the code element based on a time difference between the edges of the signal; deriving a correction factor from the code elements by determining at least one of a shortest, a longest or an average for the duration of the code elements, wherein the correction factor correlates with a deviation in the signal caused by the reading; and adjusting the signal based on the correction factor.