DEVICE WHICH CHECKS BANK NOTE VALIDITY Russian patent published in 1997 - IPC

FIELD: bank equipment. SUBSTANCE: device has ultraviolet light source with gas-discharge lamp which is connected to alternating current power supply. In addition device has photodetector of visible light reflected by verified bank note, scaling amplifier and control unit. Photodetector of ultraviolet light , clipping amplifier, high-pass filter, demodulator and low-pass filter are introduced to accomplish the goal of invention. Output of photodetector of visible light reflected by verified bank note is connected through scaling amplifier to input of high-pass filter which output is connected to first input of demodulator, which output is connected to input of low-pass filter. Output of low-pass filter is connected to input of control unit. Output of ultraviolet light photodetector is connected to second input of demodulator through clipping amplifier. Threshold frequency of high-pass filter is less than minimal value of frequency of signal at input of photodetector of photodetector of visible light reflected by verified bank note. Threshold frequency of low-pass filter is less than frequency of alternating power supply. This results in possibility to prevent false firing of control unit. EFFECT: increased stability to noise against optical, electric and electromagnetic interference. 1 dwg