Method and apparatus for coin sorting and counting

Abstract

This is a coin sorting and counting apparatus for providing very accurate high throughput processing of heterogeneous coin mixtures. A rotating drum having parallel annular channels, each of which has equally spaced counterbores located around it is rotated within a vacuum plenum. A novel sensor coil constructed as a balanced transformer of four coils having rectangular geometries is used, in conjunction with a dual frequency excitation signal, to detect at least three electronic signatures for each coin, the signatures are detected by separating the frequency components in the output of the sensor coil and obtaining a peak value for the excursion of the high frequency response caused by passage of the coin, and width values corresponding to the time the excursion of the signal was above a predetermined threshold for both the high and low frequency responsive channels. Based on the denomination determined, appropriate signals are inserted into a coin ejection memory queue which is shifted in synchronism with rotation of the drum. The memory queue is constructed so that an appropriate air valve will be activated when the detected coin is over an appropriate one of a plurality of coin receiving stations. A set of lag sensors are used downstream from the coin ejecting air valves to confirm proper ejection of the coins. Separate calibration values for the signature signals are acquired and saved for each counterbore location to offset the effects of variations in circuitry on a channel-by-channel basis and slight mechanical irregularities in movement of the counterbores past the sensor array.