Solid-state image intensifier with variable contrast ratio

Claim 1

A SOLID-STATE IMAGE INTENSIFIER COMPRISING A COMPOSITE SOLID PLATE INCLUDING AN AUXILIARY ELEMENT AND THREE PRINCIPAL ELEMENTS, SAID PRINCIPAL ELEMENTS CONSISTING OF AN ELECTROLUMINESCENT ELEMENT, A PHOTOCONDUCTIVE ELEMENT AND AN ELECTRICAL IMPEDANCE ELEMENT, POSITIONED IN A SANDWICH RELATIONSHIP, EACH OF SAID PRINCIPAL ELEMENTS BEING INSULATED FROM EACH OTHER AND HAVING ELECTRODES CONNECTED THERETO, ELECTRICAL POWER MEANS CONNECTED TO SAID ELECTRODES WHEREBY THE ELECTROLUMINESCENT ELEMENT INFLUENCED BY THE PHOTOCONDUCTIVE AND ELECTRICAL IMPEDANCE ELEMENT EXHIBITS A VISIBLE LIGHT SIGNAL IN ACCORDANCE WITH AN INCIDENT RADIATION SIGNAL APPLIED TO THE PHOTOCONDUCTIVE ELEMENT, SAID ELECTRICAL POWER MEANS PROVIDING ALTERNATING CURRENT VECTOR VOLTAGES V1 AND V2 HAVING THE SAME FREQUENCY, VARIABLE PHASE SHIFTING MEANS FOR FEEDING SAID ALTERNATING CURRENT VECTOR VOLTAGES V1 AND V2 OF THE SAME FREQUENCY AT A VARIABLE PHASE DIFFERENCE ACROSS SAID ELECTROLUMINESCENT AND PHOTOCONDUCTIVE ELEMENTS AND ACROSS SAID ELECTROLUMINESCENT AND ELECTRICAL IMPEDANCE ELEMENTS RESPECTFULLY, SAID ELECTRICAL POWER MEANS PROVIDING SAID V1 VOLTAGE WITH AN ABSOLUTE VALUE IN A RANGE WHEREBY SAID ELECTROLUMINESCENT ELEMENT PRODUCES A LUMINESCENCE OF SATISFACTORY INTENSITY IN RESPONSE TO THE ALTERNATING CURRENT ASSOCIATED WITH SAID VOLTAGE AT LEAST UNDER THE CONDITION OF MAXIMUM CONDUCTIVITY OF SAID PHOTOCONDUCTIVE ELEMENT, SAID ELECTRICAL POWER MEANS FURTHER PROVIDING SAID V2 VOLTAGE WITH AN ABSOLUTE VALUE CORRESPONDING TO A POINT OF MAXIMUM LUMINESCENT INTENSITY ON A CHARACTERISTIC CURVE OF THE ABSOLUTE VALUE OF V2 VERSUS THE LUMINESCENT INTENSITY OF THE ELECTROLUMINESCENT ELEMENT IN WHICH THE VOLTAGE V1 HAS A FIXED ABSOLUTE VALUE WHEN THE PHASE DIFFERENCE BETWEEN VOLTAGES V1 AND V2 IS FIXED AT A CRITICAL VALUE 0C, WHICH CORRESPONDS TO THE POINT OF MINIMUM LUMINESCENT INTENSITY ON THE CHARACTERISTIC CURVE OF THE PHASE DIFFERENCE 0 BETWEEN SAID VOLTAGES V1 AND V2 VERSUS THE LUMINESCENT INTENSITY OF SAID ELECTROLUMINESCENT ELEMENT, AS OBTAINED WITH THE ABSOLUTE VALUES OF SAID VOLTAGES FIXED WITH THE PHOTOCONDUCTOR ELEMENT AT A MINIMUM CONDUCTIVITY, WHEREBY SAID VARIABLE PHASE SHIFTING MEANS PROVIDES MEANS FOR VARYING THE LIGHT TRANSDUCING CHARACTERISTIC OF SAID ELECTROLUMINESCENT ELEMENT, SAID VARIABLE PHASE SHIFTING MEANS COMPRISING A PLURALITY OF FOUR-ELEMENT FOUR-TERMINAL PHASE-SHIFTER CIRCUITS IN CASCADE CONNECTION, EACH OF SAID CIRCUITS HAVING A PAIR OF VARIABLE RESISTANCES ARRANGED IN ONE PAIR OF OPPOSITE ARMS OF THE CIRCUIT FORMING A GANG RESISTOR, AND A PAIR OF CAPACITORS ARRANED IN THE OTHER PAIR OF OPPOSITE ARMS OF THE CIRCUIT; AND VACUUM-TUBE TRANSFORMER LOAD CATHODE FOLLOWERS, EACH HAVING A SECONDARY COIL ON THE OUTPUT SIDE TO WHCIH A PAIR OF OPPOSITE TERMINALS OF SAID PHASE-SHIFTER CIRCUIT ARE BALANCE-CONNECTED, AND RESISTOR MEANS CONNECTED IN PARALLEL WITH SAID SECONDARY COIL WHEREBY THE VALUE OF THE LOAD IMPEDANCE ON THE SECONDARY COIL SIDE OF SAID VACUUM-TUBE TRANSFORMER OUTPUT CATHODE FOLLOWER IS LOWER THAN THE MINIMUM IMPEDANCE VALUE OF THE ASSOCIATED FOURTERMINAL PHASE-SHIFTER CIRCUIT, AND THE OTHER PAIR OF OPPOSITE TERMINALS OF EACH OF SAID FOUR-TERMINAL PHASE-SHIFTER CIRCUITS IS CONNECTED OUT OF BALANCE TO THE INPUT CIRCUIT OF AN ASSOCIATED VACUUM-TUBE CATHODE FOLLOWER.