Application of doctrine of equivalents to range limitation in claim does not vitiate the limitation

In a decision Friday, the Federal Circuit affirmed a district court's claim construction, but reversed its rulings regarding the sufficiency of notice of infringement and the applicability of the doctrine of equivalents.

Regarding sufficiency of notice under 35 U.S.C. 287(a), the court held that while the patentee did not mark its products, its notice of infringement via letter was sufficient where the patent holder's identity is accurately noted on the patent included with a notification letter, even if not included in the text of the letter itself.

The court also held that the doctrine of claim vitiation does not necessarily preclude application of the doctrine of equivalents when the claim language includes a range of values. The fact that the equivalent would fall outside the range specified in the claim does not necessarily mean the limitation would be vitiated.

More detail of U.S. Philips Corp. v. Iwasaki Elec. Co. after the jump.

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