Patent ID: 6900720

Claim:
An electronic key comprising: a clock; a microcomputer; an infrared communication interface for transmitting and receiving communications over an infrared band; a non-volatile memory having stored therein a key code, a power-up counter, and a clock data back-up buffer; and an activation device connected to the microcomputer and operable for generating an activation signal for triggering the microcomputer to initiate a key code transmission operation in which the infrared communication interface is used to transmit the key code stored in the non-volatile memory, wherein the microcomputer is programmed to perform a bi-directional challenge-response process during a key transmission operation with an electronic lock on a vending machine using encrypted communications through the infrared communication interface, and wherein the infrared communication interface includes an infrared transceiver having a transmission pattern with a transmission angle and a transmission power range set such that an effective width of the transmission pattern at the transmission power range is substantially identical or less than a width of the vending machine.