Federal Circuit Undoes Tribunal Decision in Imaging Patent Fight

The Federal Circuit said a tribunal erred by not invaliding parts of an imaging-system patent issued because of disclosures in a paper written by a scientist at the Mayo Clinic describing using an X-ray beam to view rodent organs.

The board improperly narrowed the scope of the patent to distinguish its claims from the earlier paper, District Judge Mitchell S. Goldberg of the Eastern District of Pennsylvania, who sat on the three-judge appeals court panel by designation, said in a precedential opinion issued Friday by the US Court of Appeals for the Federal Circuit.

Optics company Carl Zeiss X-Ray Microscopy Inc. sued Sigray Inc. in 2020, accusing the rival of infringing two patents, including the contested US Patent No. 7,400,704, and of stealing its trade secrets. Sigray challenged the ‘704 patent at the Patent Trial and Appeal Board, arguing key claims are anticipated and rendered obvious by the 1998 paper.

The parties sparred at the board over whether the paper “inherently discloses projection magnification,” the patented feature challenged by Sigray in its PTAB petitions, according to the Federal Circuit opinion. The board answered that question no, handing Carl Zeiss a win, but it did so based on a misinterpretation of language from the patent, Goldberg said.

Carl Zeiss argued the board hadn’t construed the patent claim at all. Goldberg disagreed, however, and said the PTAB construed a limitation in the patent as narrowing its scope in a way that distinguish its claims from the invention described in the Mayo Clinic scientist’s paper.

“As the Board applied an incorrect claim construction, it never addressed anticipation under the correct construction,” Goldberg concluded.

The opinion reversed the PTAB as to three of the patents claims, and directed the tribunal to reconsider whether three other contested claims are obvious.

Lawyers for the two companies didn’t immediately respond to requests for comment.

Goldberg was joined by Judges Timothy B. Dyk and Sharon Prost.

Knobbe Martens represents Sigray. Carl Zeiss is represented by Fish & Richardson.

The case is Sigray, Inc. v. Carl Zeiss X-Ray Microscopy, Inc., Fed. Cir., 23-2211, rev’d in part, rem’d in part 5/23/25.