Again remanding a case based on claim construction, the U.S. Court of Appeals for the Federal Circuit vacated a district court’s narrow claim construction finding that it impermissibly narrowed the claim by importation of limitations from the specification. Markem-Imaje Corp. v. Zipher Ltd., Case No. 10-1305 (Fed. Cir., Sept. 9, 2011) (per curiam) (Newman, J. dissenting).
The patent-in-suit relates to transfer printing. Transfer printing uses a print head to impress an ink ribbon onto a substrate, such as plastic, using heat. The ribbon is wound onto two spools, with the print head in between the spools. One spool supplies the ribbon to the print head and the other takes up the ribbon downstream of the print head. Traditionally, the take-up spool has a motor, and the supply spool has a “slipping clutch” in order to maintain the ribbon in tension. The patent specification disclosed a push-pull system in which the angular positions of both spools are controlled by motors that receive commands from a microcontroller. The specification discloses measuring ribbon tension to determine when to activate the motors.
The relevant claim recites a “controller [that] energizes both […] motors to drive the spools in a tape transport direction” and a controller that “controls [the] motors to drive the spools.” The claim is silent as to tension measurement.
Markem-Imaje brought suit against Zipher seeking a declaratory judgment that the patent-in-suit is not infringed. At Markem-Imaje’s behest, the district court construed the term “drive” to narrowly mean “rotate.” The district court also construed the claim to require tension measurement, because one would necessarily have to measure tension to practice the claim. Based on these constructions, the district court granted summary judgment of non-infringement. Markem-Imaje appealed.
The Federal Circuit vacated the district court’s construction, limiting the claims to include a tension measurement. By analogy, the Federal Circuit stated that a claim to an engine should not be construed to include an exhaust pipe limitation, even though an engine needs an exhaust pipe. Similarly, although the tension must be measured to practice the claims, such a limitation should not be read into the claims.
The Federal Circuit also vacated the district court’s claim construction as to “drive,” adopting Zipher’s proposed construction that “drive” means “the application of torque to the spools, whether the torque causes rotation or resists it.” The Federal Circuit disagreed with the district court’s reasoning that “control” and “drive” must have different meanings, i.e., that since each term appears in the claim they should not be construed to mean the same thing. The Court explained that there is no reason why the two terms may not have “similar” meanings. The Federal Circuit further found that nothing in the specification that would limit “drive” to require rotation. Rather, the Court noted that the specification disclosed applying a holding torque to a spool.
Judge Newman dissented with respect to the Court’s engine-exhaust pipe analogy. Judge Newman would have read a tension measurement limitation into the claim, because to do otherwise would be to ignore the “paramount importance of the specification in claim construction.”
Practice Note: This case is another example of district courts’ struggle with the blurry line between importing limitations from the specification and construing claim terms in light of the specification.