Analog multiplier circuits using an electroluminescent element

Claim 1

A MULTIPLIER CIRCUIT FOR OBTAINING A FOUR QUADRANT PRODUCT OF A FIRST VARIABLE ELECTRICAL INPUT QUANTITY WITH A SECOND VARIABLE ELECTRICAL INPUT QUANTITY, SAID QUANTITIES HAVING POSITIVE OR NEGATIVE CHARACTERISTICS, COMPRISING: (A) A FIRST AND SECOND PAIR OF CELLS, EACH CELL HAVING A LIGHT EMISSIVE ELEMENT OPTICALLY COUPLED TO A PHOTOSENSITIVE ELEMENT, (B) A FIRST DISCRIMINATOR MEANS FOR COUPLING SAID FIRST VARIABLE ELECTRICAL INPUT QUANTITY OF POSITIVE CHARACTERISTIC TO THE LIGHT EMISSIVE ELEMENTS OF SAID FIRST PAIR OF CELLS AND FOR COUPLING SAID FIRST VARIABLE ELECTRICAL INPUT QUANTITY OF NEGATIVE CHARACTERISTIC TO THE LIGHT EMISSIVE ELEMENTS OF SAID SECOND PAIR OF CELLS, THE COUPLING OF SAID FIRST POSITIVE AND NEGATIVE QUANTITIES BEING MUTUALLY EXCLUSIVE, SAID FIRST INPUT QUANTITIES CONTROLLING THE LIGHT EMISSION FROM SAID LIGHT EMISSIVE ELEMENTS, (C) A SECOND DISCRIMINATOR MENS FOR COUPLING SAID SECOND VARIABLE ELECTRICAL INPUT QUANTITY OF POSITIVE CHARACTERISTIC TO THE PHOTOSENSITIVE ELEMENTS OF ONE CELL OF EACH OF SAID FIRST AND SECOND PAIR OF CELL AND FOR COUPLING SAID SECOND VARIABLE ELECTRICAL INPUT QUANTITY OF NEGATIVE CHARACTERISTIC TO THE PHOTOSENSITIVE ELEMENTS OF THE OTHER CELL OF EACH OF SAID FIRST AND SECOND PAIR OF CELLS, THE COUPLING OF SAID SECOND POSITIVE AND NEGATIVE QUANTITIES BEING MUTUALLY EXCLUSIVE, SAID SECOND INPUT QUANTITIES CAUSING CURRENT TO PASS THROUGH SAID PHOTOSENSITIVE ELEMENTS SO AS TO PROVIDE AN OUTPUT ELECTRICAL QUANTITY PROPORTIONAL TO A PRODUCT OF SAID FIRST AND SECOND INPUT QUANTITIES, AND (D) OUTPUT MEANS RESPONSIVE TO SAID OUTPUT ELECTRICAL QUANTITY.