Device for controlling the displacement speed of a sample to be scanned, particularly for a recording microdensitometer

Claim 1

IN A MICRODENSITOMETER DEVICE HAVING TWO OPTICAL SYSTEMS TRAVERSED BY TWO LUMINOUS BEAMS AND A PHOTOELECTRIC CELL FOR COMPARING SAID LUMINOUS BEAMS SO THAT A DISCREPANCY SIGNAL CAN BE PRODUCED BY SAID CELL, ONE OF SAID OPTICAL SYSTEMS INCLUDING A MOVABLE OPTICAL WEDGE HAVING A VARIABLE OPTICAL DENSITY ACCORDING TO A KNOWN FUNCTION, THE OTHER OPTICAL SYSTEM BEING ADAPTED FOR THE DISPLACEABLE SUPPORT OF A SAMPLE TO BE ANALYZED IN THE PATH OF THE RESPECTIVE LIMINUOUS BEAM, A FIRST ELECTRIC MOTOR COUPLED TO SAID WEDGE TO MOVE THE SAME, SO THAT SAID DISCREPANCY SIGNAL BECOMES ZERO ACCORDING TO THE POSITION OF THE SAMPLE TO BE ANALYZED SAID SAMPLE HAVING A VARIABLE OPTICAL DENSITY GRADIENT WHICH IS TO BE DETERMINED THE COMBINATION COMPRISING A SECOND ELECTRIC MOTOR COUPLED TO SAID SAMPLE TO MOVE THE SAME, A TACHOMETER GENERATOR DRIVEN BY SAID FIRST MOTOR AND SUPPLYING A VOLTAGE VT WHILE SAID FIRST MOTOR IS COUPLED TO SAID CELL TO BE SUPPLIED WITH A VOLTAGE VC WHICH IS A FUNCTION OF SAID DISCREPANCY SIGNAL ISSUED FROM SAID CELL, A DETECTING, AMPLIFYING AND RECTIFYING UNIT COUPLED TO SAID GENERATOR AND TO SAID FIRST MOTOR FOR RECEIVING SAID VOLTAGES VT AND VC AND FOR PLACING SAID VOLTAGES VT AND VC IN A 180* PHASE-DISPLACEMENT RELATIONSHIP WHEREBY A RESULTING D.C. VOLTAGE IS PRODUCED, A MODULATOR DEVICE AND A REFERENCE VOLTAGE GENERATOR FOR SUPPLYING SAID MODULATOR DEVICE WITH AN A.C. VOLTAGE, SAID MODULATOR DEVICE BEING COUPLED TO SAID DETECTING AMPLIFYING AND RECTIFYING UNIT FOR BEING CONTROLLED BY SAID RESULTING D.C. VOLTAGE WHEREBY AN A.C. VOLTAGE VO IS PRODUCED BY SAID MODULATOR DEVICE DEPENDENT UPON SAID RESULTING VOLTAGE AND AN AMPLIFIER DEVICE COUPLED TO SAID SECOND MOTOR TO APPLY AN AMPLIFIED VALUE OF VOLTAGE VO TO SAID SECOND MOTOR SO THAT THE SAMPLE DRIVEN THEREBY IS MOVED AT A SPEED WHICH VARIES IN INVERSE RATIO TO THE GRADIENT VALUE OF THE DENSITY OF SAID SAMPLE.