PHOTODETECTOR OF INFRARED LABELS Russian patent published in 1998 - IPC

FIELD: image recognition, in particular, verification of authenticity of bank notes which are printed using paint with luminophore which is induced by infrared light and outputs composition in visible light wavelength. SUBSTANCE: device has infrared diode emitter, photodetector and power supply. In addition device has first and second scaling amplifiers, inertia line, reference voltage source, difference signal generator, current regulator for current which runs through infrared diode emitter, current clipping resistor and current setting resistor. Photodetector and inputs of first scaling amplifier are connected through current setting resistor in parallel to power supply lines. Output of first scaling amplifier is connected to input of inertia line and output of photodetector. Output of inertia line is connected to first input of circuit which generates difference signal. Output of circuit which generates difference signal is connected to input of second scaling amplifier, which output is connected to first control input of current regulator. Second input of current regulator is connected through serial circuit of infrared diode emitter and current clipping resistor to power supply line. Output of reference voltage source is connected to second input of circuit for generation of difference signal. Inertia line is designed as resistor which is connected between input and output and is by-passed by reverse- inserted diode. Output of line is by-passed with respect to common line of housing by means of capacitor. EFFECT: improved design. 2 cl, 2 dwg