Entron on Maryland, Inc. v. Jerrold Electronics Corporation

295 F.2d 670, 131 U.S.P.Q. (BNA) 209, 1961 U.S. App. LEXIS 3462
CourtCourt of Appeals for the Fourth Circuit
DecidedOctober 13, 1961
Docket8302
StatusPublished
Cited by43 cases

This text of 295 F.2d 670 (Entron on Maryland, Inc. v. Jerrold Electronics Corporation) is published on Counsel Stack Legal Research, covering Court of Appeals for the Fourth Circuit primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Entron on Maryland, Inc. v. Jerrold Electronics Corporation, 295 F.2d 670, 131 U.S.P.Q. (BNA) 209, 1961 U.S. App. LEXIS 3462 (4th Cir. 1961).

Opinion

SOBELOFF, Chief Judge.

The two patents here in suit relate to a device used in effecting a tap-off of high frequency signals from a coaxial transmission line. Its primary use is in supplying the necessary impulse to an individual television set by connecting an auxiliary cable to the main line. The device, commercially known as the Fastee, is covered by U.S. Patent Nos. 2,694,-182 and 2,694,183. The application for the first, called “Impedance-Matching Tap-Off Coupler for Wave Transmission Lines,” was filed on February 20, 1953, and for the second, an improvement patent, called “Tap-Off Coupler with Fixed Attenuation for Coaxial Lines,” on September 29, 1953. Both issued on November 9, 1954.

Entrón of Maryland, Inc., assignee of the patents, appeals from the District *671 Court’s determinations of invalidity for lack of invention and non-infringement. D.C.D.Md.1960, 186 F.Supp. 483.

The coaxial cables with which we are here concerned consist of a central conductor surrounded by a tough insulating material called a dielectric, and surrounding this is a cylindrical conductor, usually a copper braid, which in turn is covered by an outer insulation. They are particularly adaptable to modern use in the transmission of high frequency, multiple-band television signals. With the advent of community television antenna systems, around 1950, the need arose for a device to connect a branch cable to a main transmission line. It was necessary to connect the outer conductor of the main cable with the outer conductor of the branch line and to connect the inner conductors of the two cables 'without shorting. Also, as the connection might be made outdoors, any device, to be satisfactory, had to be quickly installable and easily waterproofed.

The plaintiff’s patent claims 1 describe two components. There is a metallic clamping means to hold the transmission line, which has two short pins to pierce the outer insulation of the cable and make contact with the tubular outer braid. There is also a threaded aperture *672 in the clamp into which is screwed the second component, having an insulated pin with an uninsulated point and a threaded metallic outer shell. The pin is forced into the cable to malee contact with the solid inner conductor by engaging and screwing the threaded outer shell of the second component into the threaded aperture of the clamp. This is an application of the so-called “screw-jack” principle. The pin is rigidly constructed and serves as the terminal member of the tap-off’s inner conductor and has attached thereto an impedance element. The outer shell, and the pin and impedance element are separated but rigidly joined by a mechanically strong dielectric. The rearward extension of the outer shell, dielectric, and inner conductor is constructed to form a connector for the branch line.

Prior Art

The defendant argues that the plaintiff’s patent is but an obvious combination of five parts, each of which is old in the art. To this end it introduced at the trial (1) patents showing an insulated pin with an uninsulated point, (2) patents showing either attachment or piercing by the screw-jack principle, (3) patents showing an integrally connected impedance element, (4) patents showing .an internally included dielectric and (5) patents showing a metallic outer shell.

The prior art primarily relied on by the defendant to overcome the presumption of the patents’ validity 2 is comprised of the 1401 and the Holt taps, in prior use, and the following patents: Kamen, 2,615,948, filed November 3, 1949; Brady, 2,677,108, filed March 22, 1950; Bennett, 2,798,204, filed June 30, 1951; Eriksen, 2,552,414, filed June 8, 1948; Weissmann, 1,136,384, filed March 18, 1914; Boothby, 2,598,671, filed October 16, 1945; Hall, 1,067,024, filed October 19, 1912; More, 2,758,280, filed May 29, 1952; and Cork, 2,490,622, filed May 15, 1943.

The 1401, a coupler manufactured by the defendant in 1950, was intended for use on the % inch RG/59 cable, then predominant. To install the 1401 the transmission cable had to be severed and the device affixed to the loose ends. Internally the 1401 had a lead for the inner conductor of the transmission cable, intersected by a branch lead. The device had an attached impedance element and its internal parts were encased in a small “T” shaped metal container.

The Holt tap, marketed in 1951, could be used on the larger % inch RG/11 cable, then coming into commercial use. It did not require severing of the transmission line. With this device the cable was punched by a screw vise through to the solid inner conductor of the cable and an insulated pin with an uninsulated point inserted in the cavity. The pin served as the terminal member of the branch lead and had an attached impedance element. The pin and impedance were held in place by a “T” shaped metal container with the top of the “T” comprising a split flange sliding lock to hold the transmission line.

The Kamen patent, a “Coupler for Wave Transmission Lines,” discloses a clamp, to hold the transmission line, having three threaded apertures. After appropriate coring, an insulated probe, the terminal member of the tap-off’s inner conductor coupler, is screwed into one of the apertures to make electrical contact with the inner conductor of the cable. This probe has an associated impedance element. A second proble contacts the cable’s outer braid; the third makes no conductive contact with the transmission cable, but serves as a connector of the outer braid of the branch line with the clamp.

Brady, also a coaxial coupler, is quite similar to Kamen. Although the defendant contends that Brady teaches partial piercing of the main line, the patent discloses only coring to within a few thousandths of an inch of the inner con *673 ductor of the cable and insertion of an insulated probe. Conductive contact between the probe and the inner conductor of the cable is accomplished by pressure of a spring on the probe, which causes the remaining layer of dielectric to “flow” from the point of the probe. Brady uses this method so that only slight electrical discontinuity will occur at the connection point.

Bennett, a “Branch Line Connector,” teaches, as described by the District Court, “a clamping device for reception of the main coaxial cable, which when screwed into place would cause metallic points to be driven into contact with the outer conductor, and would force another pin ‘through the clamped cable outer conductor and inner dielectric between inner and outer conductors’ to ‘the point where the protruding pin point just makes firm contact with the main cable inner conductor.’ A dielectric protrusion surrounding the pin shields it from contact with the main cable outer conductor. * * * Bennett does not have a conductive shell around the parts above the piercing contact pin, and hence the tap-off unit is not concentric. The whole unit is used in a terminal box, intended to eliminate radiation.”

Eriksen teaches a device to attach the end of a coaxial cable to a junction box. The device is in two parts. One slips on to the end of the cable and, by wedging, separates the outer braid from the dielectric and inner conductor. The second part is then screwed into the first.

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Bluebook (online)
295 F.2d 670, 131 U.S.P.Q. (BNA) 209, 1961 U.S. App. LEXIS 3462, Counsel Stack Legal Research, https://law.counselstack.com/opinion/entron-on-maryland-inc-v-jerrold-electronics-corporation-ca4-1961.