Charles Walton, inventor of the RFID technology, died Nov. 6 at the age of 89 in California, according to Network World. A memorial service is set for Dec. 18 in Los Gatos.

According to a story on the history of radio frequency identification technology in RFID Journal, Mario Cardullo received a patent in 1973 for an active RFID tag with rewritable memory and that same year, "Charles Walton, a California entrepreneur, received a patent for a passive transponder used to unlock a door without a key. A card with an embedded transponder communicated a signal to a reader near the door. When the reader detected a valid identity number stored within the RFID tag, the reader unlocked the door. Walton licensed the technology to Schlage, a lock maker, and other companies."

According to Venture Beat report, Walton received 50-plus patents during his career, including one for a digital version of RFID that advanced the earlier passive models. However, the report notes that some of Walton's key patents expired in the mid-1990s, not enabling him to gain a huge windfall from the rapid adoption of RFID after that by organizations such as the Department of Defense.