IP Law Daily, PATENT—N.D. Cal.: Hard-disk drive patents were not abstract, (Feb 4, 2026)

By Kevin M. Finson, J.D.

The asserted patents, despite being mathematical in nature, were directed toward specific technological improvements, not an abstract idea.

Carnegie Mellon University properly pleaded infringement of two patents relating to hard-disk drive technology, the U.S. District Court in San Francisco has held. The claims were related to methods for reducing errors in magnetic storage drives and were not directed at a patent-ineligible concept. The motion to dismiss was denied because even though mathematical principle were relied on, a concrete technological improvement was created (Carnegie Mellon University v. LSI Corp., No. 3:18-cv-04571-JD (N.D. Cal. Feb. 3, 2026)).

Patents. Carnegie Mellon University (Carnegie Mellon) is the owner of U.S. Patents Nos. 6,201,839 (the ’839 patent) and 6,438,180 (the ’180 patent), both of which related to mathematical methods involving “branch metric values for branches of a trellis for a Viterbie-like detector” which the Federal Circuit had previously described in other litigation as “an improvement over existing detectors by teaching use of branch metric functions that are specifically adapted to reduce the effects of the most likely errors caused by the ever smaller magnetic regions used for storing data on hard disks.” Carnegie Mellon brought suit for infringement of both patents against LSI Corporation (LSI), a manufacturer of hard-disk drives. LSI moved to dismiss on the ground that the asserted claims were directed to patent ineligible abstract ideas. The court applied the two-step Alice test.

Abstract idea. The parties agreed that claim 4 of the ’839 patent was representative for the purposes of the motion. LSI argued the claim was abstract as a “purely mathematical method” of determining branch metric values. The court found that the plain language of the patent established otherwise: it was not directed to the general mathematical principle of determining branch metric values but was instead a specific means or method to improve sequence detection of stored bits in memory channels which improved the performance of hard disk drives. This was a specific technological improvement, not an abstract idea.

Because it found that the asserted claims were not directed to an unpatentable abstract idea, the court denied the motion to dismiss without reaching step two of the Alice test.

The Case is No. 3:18-cv-04571-JD.

Judge: Donato, J.

Attorneys: Anna Shabalov (K and L Gates LLP) for Carnegie Mellon University. Steven Jay Rizzi (McKool Smith, PC) for LSI Corp.

Companies: Carnegie Mellon University; LSI Corp.

Cases: Patent CaliforniaNews