Hewlett-Packard Company v. Tel-Design, Inc.

Hewlett-Packard Company appeals from a judgment of the district court holding U. S. Patent No. 3,290,586, claims 1 through 5, valid and infringed by the manufacture and sale of an Open Cable Pair Locator by the appellant. The district court had jurisdiction under 28 U.S.C. § 1338 (a), this being an action arising out of the patent laws of the United States. Our jurisdiction is based on 28 U.S.C. § 1291 .

U. S. Patent No. 3,290,586 (hereinafter the “Anderson patent”), known as an “open fault locator” was issued to Robert E. Anderson on December 6, 1966, who in turn assigned all rights in the patent to appellee Tel-Design, Inc. The open fault locator device is used by telephone craftsmen to locate breaks in telephone cables. It relies on the physical fact that the capacity of a telephone cable is proportional to its length. Standard telephone cable is manufactured to have a capacity of .083 microfarad per mile within each pair of wires. Thus, if a capacity measurement from a test point shows that a cable pair has'a capacity of .083 microfarad, the cable pair ends (that is, the break occurs) one mile from the test point.

The instrument in question measures capacity by means of the…