TiVo Corp. won a key victory in its royalty battle with Comcast Corp. when a U.S. trade judge said the cable provider was using its patented inventions without permission and recommended imports of some Comcast X1 set-top boxes be banned.

U.S. International Trade Commission Judge MaryJoan McNamara found that Comcast infringes a patent owned by Rovi for a content search function, while there was no violation of two other patents. The judge’s findings are subject to review by the full...