Dual coil coin identifier

Abstract

The coin identification device comprises a gravity fed chute structure having an opening for receiving a coin to be identified, walls to guide the coin as it moves through the chute and an opening for the coin to exit. A wake-up circuit with sensing coils mounted near the chute opening provides an output signal when the presence of a coin is detected. Two coin sensing circuits, each having an oscillator with a particular coil arrangement are used to sense the characteristics of the coin passing through them. The first coin sensing circuit includes a coil arrangement having a coil mounted on the chute with its axis in the direction of the coin path such that the coin will pass through it and forming part of a first oscillator to create lines of flux parallel to the coin path. The second coin sensing circuit includes a coil arrangement having a coil mounted on a U-shaped core with two substantially parallel legs connected at one end by an arm that is mounted about the chute to have the coin pass in the gap between the core legs. The second coil arrangement forms part of a second oscillator to create lines of flux perpendicular to the plane of the coin passing through the chute. The first and second oscillators are adapted to oscillate at one or more base frequencies. The frequency shift of the first oscillator is measured as the coin passes through the first magnetic field and the frequency shift of the second oscillator is measured as the coin passes through the second magnetic field to generate signatures of the coin characteristics. A microprocessor compares the generated signatures to known coin signatures to identity of the coin.