For ensuring that a vending machine motor will continue to operate until a product has descended through a vending space or an established time interval has elapsed, an optical beam is established across the vend space through which a product must drop. A change in beam intensity is detected. By preference...http://www.google.com/patents/US20080121648?utm_source=gb-gplus-sharePatent US20080121648 - Optical vend-sensing system for control of vending machine
