Photoelectric bridge circuit with indicator compensated for non-linear input

Claim 1

AN INDICATING CIRCUIT FOR COMPENSATING FOR NONLINEARITY OF AN INDICATING DEVICE WITH RESPECT TO A PARAMETER OF AN ARTICLE TO BE MEASURED AND INDICATED, SAID MEASURING CIRCUIT COMPRISING: A DIFFERENTIAL CIRCUIT INCLUDING A BRIDGE WITH TWO PHOTOELECTRIC DETECTING MEANS CONNECTED IN TWO DIFFERENT ARMS OF SAID BRIDGE SO THAT SAID DIFFERENTIAL CIRCUIT IS RESPONSIVE TO THE PARAMETER TO BE MEASURED AND INDICATED, SAID DIFFERENTIAL CIRCUIT PRODUCING A D.C. SIGNAL AT THE OUTPUT THEREOF, WHICH SIGNAL CHANGES IN POLARITY AS THE FUNCTION TO BE INDICATED VARIES ABOVE AND BELOW A STANDARD VALUE; A COMPARISON CIRCUIT INCLUDING A BALANCED PAIR OF AMPLIFIERS ELECTRICALLY CONNECTED TO THE OUTPUT OF SAID DIFFERENTIAL CIRCUIT, THE GAIN OF SAID AMPLIFIERS BEING ADJUSTABLE SELECTIVELY FOR INPUT SIGNALS OF POSITIVE AND NEGATIVE VALUE APPLIED THERETO AND INCLUDING A PAIR OF OUTPUT TERMINALS ACROSS WHICH IS ESTABLISHED A POTENTIAL SIGNAL DIFFERENCE IN RESPONSE TO A D.C. SIGNAL APPLIED TO THE INPUT OF SAID COMPARISON CIRCUIT, THE DIRECTION AND MAGNITUDE OF SAID POTENTIAL SIGNAL DIFFERENCE BEING DEPENDENT ON THE POLARITY AND MAGNITUDE OF THE D.C. SIGNAL APPLIED TO THE INPUT OF SAID COMPARISON CIRCUIT, AND COMPENSATED INDICATING MEANS FOR PROVIDING AN ACCURATE INDICATION OF THE VALUE OF THE FUNCTION TO BE INDICATED, SAID COMPENSATED INDICATING MEANS INCLUDING AN INDICATING DEVICE, AT LEAST ONE RESISTOR, AND AT LEAST ONE RECTIFIER ARRANGED AND ELECTRICALLY CONNECTED TOGETHER ACROSS THE TWO TERMINALS OF SAID COMPARISON CIRCUIT SO AS TO INHIBIT THE FLOW OF SIGNAL CURRENT THROUGH SAID RESISTOR IN ONE DIRECTION IN RESPONSE TO THE EXISTENCE OF A D.C. SIGNAL OF ONE POLARITY APPLIED TO THE INPUT OF SAID COMPARISON CIRCUIT, AND TO ALLOW A PREDETERMINED AMOUNT OF SIGNAL CURRENT TO FLOW THROUGH SAID RESISTOR IN THE DIRECTION OPPOSITE TO SAID ONE DIRECTION IN RESPONSE TO THE EXISTENCE OF A D.C. SIGNAL OF A POLARITY OPPOSITE SAID ONE POLARITY SO AS TO DIMINISH THE EFFECTIVE SENSITIVITY OF SAID INDICATING DEVICE.