Matrix encoder for resistive sensor arrays

An encoder comprising:

• plural resistive sensors including a common array having at least one predetermined resistance to be detected;
• matrix means including plural inputs and plural outputs interconnected to said plural resistive sensors such that each sensor is connected between a different pair of the inputs and outputs;
• high impedance means terminating each of said plural input conductors of said matrix means;
• sampling control means for sequentially applying a predetermined voltage to each of said plural inputs of said matrix means effective to produce sensing currents flowing through the ones of said sensors being commonly connected to an input being energized with each sensing current flowing to said plural outputs, said sensing currents having a predetermined magnitude when flowing from a sensor having said predetermined resistance;
• constant voltage means terminating each of said plural outputs of said matrix means for maintaining minimum voltage differences between said plural outputs for all values of said sensing currents;
• current measuring detector means responsive to said sensing currents separately occurring in said plural outputs for producing a detection signal indicating when said sensing currents have said predetermined magnitude.

An optoelectronic encoder for a radiation responsive sensor array comprising:

• plural photoconductive sensors forming said array, each of said plural sensors having a predetermined low resistance and having a predetermined high resistance relative to said predetermined low resistance, both being produced by predetermined levels of encoding illumination;
• a matrix circuit means interconnecting said plural sensors and including plural parallel row conductors and plural parallel column conductors having each of the sensors uniquely connected between one of the row conductors and one of the column conductors;
• sampling control means including a plurality of outputs operative between normally high impedance conditions and sequentially controlled low impedance conditions, said outputs of said sampling control means being separately connected to each of said plural row conductors, said sampling control means further including an input connectable to a single predetermined voltage source so as to selectively energize each of said plural row conductors when said outputs thereof are in said sequentially controlled low impedance conditions;
• a detecting circuit including means terminating each of said plural column conductors of said matrix circuit means substantially at a common reference ground potential at all times, said detecting circuit further including plural current measuring detectors having common predetermined switching thresholds and further having sensing inputs separately connected to said plural column conductors of said matrix circuit means, said current measuring detectors producing detection signals having either of two signal values in response to sensing currents in said plural column conductors having either of two magnitudes when produced through different ones of said plural sensors correspondingly having either said predetermined low resistance or said high resistance.