Lektophone Corp. v. Rola Co.

Background

A company that owned a patent for a conical speaker membrane (a tympanum) sued other makers, saying their speaker parts infringed its 1918 patent. The patent described a paper-like cone of a specific size with its outer edge tightly gripped and rigidly supported between rings, and said the cone aperture should exceed nine inches. Lower courts split: one federal court ruled for the makers, another followed an earlier decision and ruled for the patent owner, creating the conflict the Court resolved.

Reasoning

The central question was whether the patent covered competing speaker parts that differed in how the cone edge was made or mounted. The Court relied on the patent’s language and on prior technology, concluding the inventor’s contribution was a narrow combination of known elements: cone size, material, and a rim rigidly clamped by rings. Because the accused devices had important differences — for example the rim was a separate piece or made of different material and not rigidly mounted as claimed — they did not fall within the patent’s precise claim. The Court therefore affirmed the defendant win in one case and reversed the plaintiff’s earlier victory in the other.

Real world impact

The opinion confines the patent to the exact combination described, making it harder for the patent owner to stop similar speaker designs that change the rim or its mounting. The decision also resolves the conflicting lower-court outcomes and leaves manufacturers more room to make varied cone speakers without automatic liability.