Sensor control system and method compensating for degradation of the sensor and indicating a necessity of service prior to sensor failure

A sensor control system controlling an output of a plurality of sensors which detects whether an object is located in a corresponding object location near each of said sensors, comprising:

• for each of said plurality of sensors:
• a comparator comparing an analog output signal of said sensor with a reference voltage signal and in response to said comparing providing a digital output signal which indicates a presence or an absence of an object in said object location;
• means for adjusting said reference voltage signal in response to said analog output signal of said sensor, wherein the reference voltage signal is adjusted to have a value within a window ranging between a null state value indicating that an object is not located in said object location and an activated state value indicating that an object is located in said object location, said adjusted reference voltage signal biased toward said null state;
• and
• means for providing a service signal indicating a requirement for service of the sensor if a difference between said activated state value and said null state value is less than a predetermined value;
• wherein said means for adjusting and said means for providing for each of said plurality of sensors is comprised by a single microprocessor.

A sensor control method of controlling an output of a sensor which detects whether an object is located in an object location, said method comprising the steps of:

• comparing an analog output signal of said sensor with a reference voltage signal;
• providing in response to said comparing step a digital output signal which indicates a presence or an absence of an object in said object location;
• adjusting said reference voltage signal in response to said analog output signal of said sensor, wherein the reference voltage signal is adjusted to have a value within a window ranging between a null state value indicating that an object is not located in said object location and an activated state value indicating that an object is located in said object location, said adjusted reference voltage signal biased toward said null state;
• and
• providing a service signal indicating a requirement for service of the sensor if a difference between said activated state value and said null state value is less than a predetermined value.