Doctrine of Equivalents Could Be Used to Expand Concentration Range in Patent Claims

Case: US Philips Corp. v. Iwasaki Elec. Co. Ltd., Fed. Cir. No. 2007-1117 11/2/07)

The One Sentence Summary: The doctrine of equivalents could allow a jury to determine that a concentration of halogens in a lamp was close enough to a concentration range stated in the claims.

Federal Circuit Holdings:

• A licensing demand letter that included a copy of the patent provided adequate notice of the identity of the owner under 35 U.S.C. § 287(a) to start patent damages.
• The district court correctly construed a range between 10 to the minus 6 and ten to minus four micromoles per cubic meter.
• The doctrine of equivalents could have been applied by a jury to determine that a concentration near a stated range was equivalent - this would not vitiate the limitations.