Paper currency recognition system in money exchange machine, controls MOSFET and control chip for regulating induction and LED driving current respectively, to maintain constant light intensity

摘要

A central processing unit (CPU) controls the operation of transmitter (1) with light emitting diode (LED) (11) and control chip (13), and the operation of receiver (2) with phototransistor (21) that produces light induced induction current. The CPU controls the MOSFET (23) and the control chip for regulating the induction current and LED driving current respectively, to maintain constant light intensity.