His earlier patent, issued in 2001 for exchanging unwanted gifts online, is 6,321,211.

That idea also echoes the design found in many earlier patents.

Prior art can include earlier patents, academic papers, magazine articles, web pages, and even physical examples.

The table below lists several early patents for active magnetic bearings.

A few of the early patents that Baker received included:

By asserting such a link to the early patent, he could argue that he had invented the technology long before anyone else.

These are the two earliest patents for fluorocarbon ski waxes.

Another early patent, 4,762,712, covers milk and eggs designed to ward off stomach infections.

One of the earliest patents for a cellular repeater, issued November 1988.

He had an earlier patent on a steel process.