Brief history of X-ray tube patents

• Analysis of patents on X-ray devices and applications.
• Historical basis of the discovery of X-rays outlined.
• First patent that was published in record time (few weeks) since its discovery.
• Strong patenting from 1896 to present day.

An X-ray tube is essentially a vacuum glass tube that produces X-rays from cathode rays striking a metal target. They were discovered by Wilhelm Conrad Röntgen in Würzburg, Germany, on November 8, 1895, who published on December 28, 1895. This discovery played a role in the beginning of revolutionary changes in the understanding of the physical world. The first patent was published on March 21, 1896, in record time by Siemens & Halske (S&H) Company. Soon other patents for new advances were claimed. A remarkable development was proposed by William David Coolidge's patent in 1913 with General Electric (GE). Surprisingly, Röntgen did not apply for patents for the inventions based on his discoveries, and donated the money from his Nobel Prize to the University of Würzburg. This paper presents a brief history about this amazing discovery and its notable related patents. More than 19,000 patents were filed around the world until 2013 according to searches made on the European Patent Office databases. For the same period there were published 277 patents naming Röntgen in the title or abstract, and 648 using Roentgen. Up to the so-called golden era (1950s) most of the patents were from companies such as Philips, GE and Westinghouse, by a range of different inventors.