principal patent

The outline sketch will indicate the principal patents covering the basic features of the lamp.

Claude's principal patent expired in 1932, which led to a great expansion in the production of neon signage.

Several researchers in the late 1940s, including Jay Forrester, conceived the idea of using magnetic cores for computer memory, but Forrester received the principal patent for his invention of the coincident core memory that enabled the 3D storage of information.