Portable high frequency bank note verification device

摘要

The bank note verification device has three electrodes (5,6,7) arranged in a line. A high frequency oscillator is connected to the input electrode (5). The output electrode (7) is connected to an amplifier (2), whose output is fed to an evaluation circuit (3). The evaluation circuit (3) controls a display (4). A screening electrode (6) excludes spurious signals. A bank note is placed on the device with its security strip (8) held at a fixed distance from the electrodes (5,6,7) by a press bar (10). The input signal then appears at the amplifier (2) input with amplitude and phase altered in a characteristic way. The evaluation circuit (3) compares the changes with those expected from a valid bank note, and gives the appropriate output signal on the display (4).