Charles Walton, The Father of RFID

By Roland Piquepaille

In a very interesting article, the San Jose Mercury News tells us about Charles Walton, the man behind the radio frequency identification technology (RFID). Since his first patent about it in 1973, Walton, now 83 years old, collected about $3 million from royalties coming from his patents. Unfortunately for him, his latest patent about RFID expired in the mid-1990s. So he will not make any money from the billions of RFID tags that will appear in the years to come. But he continues to invent and his latest patent about a proximity card with incorporated PIN code protection was granted in June 2004. Maybe he'll be luckier with this one.

Before looking at the Mercury News article, let's search for the list of patents granted to Charles Walton. If you want to search by yourself, go to the United States Patent and Trademark Office (USPTO), then use the search feature. Alternatively, you can go directly to the Advanced Search page. Into the query box, enter the following string, "IN/Walton AND IN/Charles AND IS/CA" (without the quotes; capital letters are not necessary).

On the list of 32 patents granted to Walton, the first to be associated with the acronym RFID dates from May 17, 1983 and carries the number 4,384,288. Its title is "Portable radio frequency emitting identifier." Here is the abstract.

An automatic identification system wherein a portable identifier, preferably shaped like a credit card, incorporates an oscillator and encoder so as to generate a programmable pulse position-modulated signal in the radio frequency range for identification of the user. The identifier can be made to generate the identification signal constantly or can be made for stimulated transmission responsive to an interrogation signal. The identification signal can be preset or can be programmable by use of a programmable memory.

His latest patent, "Proximity card with incorporated PIN code protection," carries the number 6,742,714 and dates from June 1, 2004. If you look at the list of previous patents referenced by this one, you'll find his first patents, numbers 3752960 (August 1973) and 3816708 (June 1974). Unfortunately, they are not available in full text. You can still search for them and will have access to some scanned images of the patents (TIFF format).

Here is the front page of this first patent, "Electronic Identification & Recognition System" (Credit: USPTO). Here is a direct link to the original image (TIFF format).

Now, let's return to the introduction of the Mercury News article.

The next time you wave a key card to unlock the door to your office building, think of Charles Walton.

One of Silicon Valley's unsung inventors, Walton's patents on radio frequency identification, or RFID, spawned those electronic door keys. Now the technology Walton pioneered in the 1970s and 1980s is poised to change the way billions of products are tracked.

In the 1970s, Walton's RFID cards cost about $2 a piece, but he managed to make good money from his patents.

Walton, 83, made about $3 million from patenting RFID technology. But his last royalty-bearing RFID patent expired in the mid-1990s, meaning that he won't share in the potentially gigantic windfall that will be generated as Wal-Mart and the Defense Department begin to require their largest suppliers to put RFID tags millions of warehoused goods.

"I'm disappointed it ran out after 17 years," Walton said of his patents. "It's not a bad law. I can't control it and I'm not angry. I was never into stretching out the length of a patent because I was always more interested in inventing something new."

The first application was in door locks.

Walton showed the technology to the board of directors of General Motors, which rejected it as too "Buck Rogers." He went a year without a salary as he shopped his invention around. Then he got lucky, licensing RFID to lock maker Schlage to make electronic locks that can open by waving a key card in front of a reader.

Walton still has a working mock-up of the door lock reader that he used to pitch Schlage. His first RFID card key was passive, meaning that it burned no battery power itself and was awakened when it came within six inches of a reader. The prototype has a 36-square-inch circuit board loaded with coiled wires and other components common in the 1970s. But there were no microchips that could house the entire RFID circuitry. Those came later, with the progress of chip miniaturization.

Other ideas didn't fare too well.

Walton modified his invention to handle automated toll collection on roads and bridges. But he put the tag in the license plate with the readers embedded in the road. But Walton was edged out by a competing RFID system that put tags in windshields and readers on the sides of toll booths.

Now, Walton lives in a house in Los Gatos and continues to file for patents.

Source: Dean Takahashi, San Jose Mercury News, June 7, 2004; United States Patent and Trademark Office