Sensor control system and method compensating for degradation of the

Abstract

A smart sheet sensor control system and method compensating for degradation of an optical sensor. A reference voltage trigger level is periodically adjusted in a manner biased toward a null state indicating an absence of a sheet of paper or document in a paper location. The reference voltage trigger level is periodically adjusted by a microprocessor to always lie within a window range between the null state value and an activated state value indicating a presence of the sheet in the paper location. Since the adjustment is periodic, the microprocessor need not be a dedicated microprocessor and may be used to adjust the reference voltage trigger level corresponding to several sensors respectively sensing the presence or absence of a sheet of paper at several different locations. A service signal may be provided via a copier controller to a display on the copier and/or to a telecommunications device to be forwarded to a vendor service department when the window range between the null state and the activated state is less than a predetermined value so that maintenance may be performed on the sensor prior to a complete failure of the sensor system. The smart sheet sensor control system and method may be implemented in an electrophotographic printing machine sensing sheets of paper or other documents at various locations within the machine.