Motion Sensor Controlled Vending Machines
The Technology
'Passive Infrared Sensors'
Most vending machine sensors use a type of technology known as passive infrared sensors (PIR), which unlike optical sensors that use an LED transmitted and infrared receiver, emits nothing. Rather than radiating, the PIR responds to infrared energy being emitted by any nearby objects. Any object with a temperature above zero degrees Celsius emits infrared energy, through black-body radiation.