A mobile electronic control device, such as an electronic key, is used to access or otherwise control the operations of a field device, such as an appliance, power tool, shipping container, etc. In a control event in which the mobile control device interacts with the field device via wired or wireless...http://www.google.com.tw/patents/US20050285716?utm_source=gb-gplus-share專利 US20050285716 - Electronic key control and management system for vending machines and the like
