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Federal Circuit Rejects PTAB’s Implicit And Incorrect Claim Construction Of “Between 1 And 10”
06/03/2025On May 23, 2025, the United States Court of Appeals for the Federal Circuit (“CAFC”) issued a precedential opinion reversing a final written decision from the U.S. Patent Trial and Appeal Board (“PTAB”) finding the challenged claims of U.S. Patent No. 7,400,704 not unpatentable. Sigray, Inc. v. Carl Zeiss X-Ray Microscopy, Inc., __ F.3d __ (Fed. Cir. May 23, 2025). In its decision, the CAFC concluded that the PTAB had implicitly and incorrectly construed claim language when considering the disclosures in the prior art.
The ‘704 patent is owned by Carl Zeiss X-Ray Microscopy, Inc. (“Zeiss”) and generally claims X-ray imaging systems that incorporate projection magnification. Projection magnification utilizes diverging X-rays that spread out as they travel from a source. Due to this divergence, the distance between the X-rays emanating from the source continues to increase after interacting with the sample being imaged and prior to being received by a detector. As a result, the generated image is larger than the sample itself.
Sigray, Inc. (“Sigray”) filed a petition for IPR of the ‘704 patent, challenging all claims as anticipated or rendered obvious by a scientific paper (“Jorgenson”) describing an x-ray imaging system. Jorgenson attempts to reduce concerns related to projection magnification by providing a large distance between the sample and the source and a short distance between the sample and the detector. It was uncontested that Jorgensen’s X-ray source creates a diverging beam that passes through a collimator before reaching the sample.
At issue in the IPR was whether Jorgenson disclosed the claim 1 limitation of a projection magnification of “between 1 and 10 times.” Zeiss conceded that a beam that is diverging, even by an undetectable amount, will result in some magnification, but asserted that Jorgensen is not anticipatory because its collimator eliminates beam divergence between sample and detector and thus results in no magnification. Sigray disagreed, arguing that Jorgensen’s collimator cannot eliminate divergence entirely but rather only reduces it, and that the any divergence will lead to at least some amount of magnification.
In its final written decision, the PTAB concluded that Sigray had not shown persuasively that Jorgensen inherently discloses projection magnification within the claimed range of “between 1 and 10 times” and, therefore, declined to hold any of the asserted claims unpatentable. The PTAB also stated that it was not engaging in claim construction.
On appeal, Sigray argued that the PTAB had legally erred by implicitly and incorrectly construing the limitation “between 1 and 10” to exclude unspecified, small divergence resulting in projection magnifications only slightly greater than 1.
In considering this argument, the CAFC first noted that the PTAB’s assertion that it was not engaging in claim construction was not dispositive as to whether claim construction occurred. Instead, the CAFC considered whether the “the outcome of the Board’s analysis establishes the scope and meaning of the claim.”
The CAFC then concluded that the PTAB had engaged in claim construction, relying heavily on the PTAB’s statement that Sigray “failed to show that the . . . X-ray beam in Jorgensen diverges enough to result in projection magnification between 1 and 10 times.” Zeiss argued, on appeal, that this single use of the word “enough” by the PTAB is taken out of context, but the CAFC disagreed. The CAFC further concluded that the evidence relied on by the PTAB supports a finding of some divergence, i.e., some magnification greater than 1.
In concluding that the PTAB had engaged in claim construction, the CAFC first noted that the PTAB decision describes the term “collimated X-ray beam” in a way that suggests that collimation reduces, without eliminating, divergence (and magnification). The CAFC further noted that the PTAB decision relied on expert testimony stating, for example, that a “collimated X-ray beam is a beam where . . . no meaningful divergence [and thus no meaningful magnification] is present” and that the beam divergence was so small that the beam could be considered a parallel source. The CAFC reasoned that this shows that the PTAB narrowed the disputed limitation to exclude magnification generated by small amounts of divergence. The CAFC also noted that the PTAB interpreted Jorgenson’s aspirational statements of purpose—that it is attempting to reduce any potential magnification—as supporting the PTAB’s conclusion that Jorgenson does not actually disclose the claimed magnification. According to the CAFC, this further demonstrates that the PTAB considered small amounts of magnification, e.g., amounts that Jorgenson’s system could not fully eliminate, as not being “between 1 and 10,” as required by the claim.
Having determined that the PTAB engaged in claim construction, the CAFC next concluded that the PTAB’s construction of “between 1 and 10” to exclude small amounts of magnification was error. To the contrary, the CAFC determined that the plain meaning of “between 1 and 10” includes tiny, even undetectable, amounts of magnification. The CAFC further emphasized that courts may not redraft claims, whether to make them operable or to sustain their validity.
Because the PTAB applied the wrong claim construction, the CAFC reversed and remanded.
