CAFC Affirms Two PTAB Obviousness Rulings in Canon Printhead Patent Disputes

The U.S. Court of Appeals for the Federal Circuit (CAFC) issued two decisions today affirming Patent Trial and Appeal Board (PTAB) final written decisions that found claims of three patents owned by Slingshot Printing LLC unpatentable as obvious. The rulings, issued in Slingshot Printing LLC v. Canon U.S.A., Inc., followed a set of inter partes review (IPR) proceedings that Canon U.S.A., Inc. and Canon Inc. brought against Slingshot’s printhead patents.

The first appeal addressed U.S. Patent No. 7,290,864, which covers a heater chip used in printheads that reduces the number of bondpads required. Claim 1 of the patent describes a bondpad that supplies power to portions of two separate heater arrays, and dependent claims 3 and 9 require that the power be delivered through traces that are “physically separated proximal to the bondpad.” Canon petitioned for IPR on claims 1 through 6 and 8 through 20, and the PTAB found all challenged claims obvious based on combinations of prior art references identified in the opinion as U.S. Patent Nos. 7,722,144, 7,278,703, and 6,582,062.

Slingshot’s appeal turned largely on claim construction, arguing the PTAB should have measured “physically separated proximal to the bondpad” against the location of the heater arrays rather than the end of the power trace. The CAFC disagreed, finding nothing in the claim language or specification that called for comparing the trace’s separation point to any structure other than the trace itself. Since the claims contained no requirement to reference the heater arrays, the CAFC agreed with the PTAB that “proximity is measured along the trace relative to the bondpad.”

Moreover, Slingshot also challenged the PTAB’s reliance on a figure from one of the prior art patents to locate the bondpad, arguing the figure lacked bondpads altogether and was not drawn to scale. The CAFC rejected that argument as well, stating that its case law does not prohibit a basic visual examination of patent figures or drawings. The PTAB had relied on that figure as well as a second prior art reference and expert testimony to conclude that a skilled artisan would understand the bondpad to sit at the edge of the heater chip, and the CAFC found that combination of evidence sufficient to meet the substantial evidence standard. Since the PTAB compared general relative distances among components in the figure rather than extracting precise proportions or particular sizes, the CAFC found no error in how the figure was used.

The second appeal involved U.S. Patent Nos. 7,484,823 and 7,594,708, which the CAFC noted share relevantly similar specifications. The patents describe a chip used in a printing device with regions between the heater arrays. Each region contains a temperature sensing element that is “substantially centrally disposed” within the region and senses its temperature. The heater arrays receive heating responsive to that sensed temperature. Canon filed separate IPR petitions against each patent, and the PTAB found all challenged claims obvious over combinations of prior art, including U.S. Patent Nos. 7,384,113 and 6,612,673.

Furthermore, Slingshot argued the PTAB relied on improper hindsight by using the patent’s own background section to support the obviousness finding. The CAFC found the PTAB had used that section only for admissions regarding what was already known in the art, not as a template for the invention itself. Additionally, Slingshot argued that a separate prior art reference taught away from the claimed invention. The CAFC found that reference merely stated that placing temperature sensors on one side of a heater chip made it unnecessary to also provide a sensor at the central portion of an ink supply port. It also noted Slingshot had not raised this argument against the specific prior art combination at issue.

Slingshot argued a skilled artisan would have had no motivation to place one reference’s thermal sense resistors into another reference’s regions, citing the cost of additional sensors and an existing single sensor design. The CAFC found that Slingshot failed to address the PTAB’s finding that the benefit of a more accurate temperature measurement in optimizing print quality would outweigh the cost concerns Slingshot raised. The CAFC also upheld the PTAB’s finding that the prior art combination taught a sensor “substantially centrally disposed” within the region. It pointed to expert testimony describing the sensor’s legs as “equidistant” and positioned approximately 680 micrometers from the heater arrays.

Ultimately, the CAFC affirmed the PTAB’s determination that all challenged claims across the three Slingshot patents are unpatentable under Section 103.