Columbia Broadcasting System, Inc. v. Zenith Radio Corp.

391 F. Supp. 780
CourtDistrict Court, N.D. Illinois
DecidedMarch 18, 1975
Docket71 C 687
StatusPublished
Cited by10 cases

This text of 391 F. Supp. 780 (Columbia Broadcasting System, Inc. v. Zenith Radio Corp.) is published on Counsel Stack Legal Research, covering District Court, N.D. Illinois primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Columbia Broadcasting System, Inc. v. Zenith Radio Corp., 391 F. Supp. 780 (N.D. Ill. 1975).

Opinion

MEMORANDUM OPINION AND ORDER

McLAREN, District Judge.

I.

INTRODUCTION

This matter arose as an action by Columbia Broadcasting System, Inc. (CB,S) for infringement of U.S. Letters Patent No. 2,690,518 (hereinafter referred to as the ’518 patent or the Fyler and Rowe patent) and infringement of U.S. Letters Patent Nos. 3,179,836 and 3,222,172 (hereinafter referred to as the Giuffrida patents). The Court has examined all of the testimony and exhibits presented, and being fully advised of the premises, finds that the Fyler and Rowe patent and Giuffrida patent 3,179,836 are valid and infringed by the Zenith Radio Corporation’s (Zenith) 1 devices. The following shall constitute the Court’s findings of fact and conclusions of law pursuant to F.R.Civ.P. 52(a).

II.

HISTORICAL BACKGROUND

The instant litigation involves three patents whose subject matter is used in color TV picture tubes. To understand the purpose of the patents in suit and *783 their place in the color TV industry, a brief excursion into the development and history of color TV is necessary. 2

Public broadcasting of television, as of radio, is lawful only when carried on under license of the Federal Communications Commission and in accordance with its prescribed “standards.” Those standards result in a single uniform type of electrical signal for each broadcasting service which home receivers are designed to receive. Prior to 1949, the FCC had adopted no standards for color television. In that year, however, the FCC invited industry proposals directed to the etablishment of such standards. An acceptable color television system requires complementary components among which are the viewing camera, the transmitter circuitry, the receiver circuitry and the picture tube at the receiving end.

CBS and RCA were early proponents of color TV systems, which were demonstrated to the FCC in November 1949 along with others. The CBS system, a “field sequential” system, was adopted by the FCC as the national standard in November 1950 and remained the national standard until December 1953. This system produced an acceptable color picture by placing a spinning disc in front of a monochrome tube. The spinning wheel system, however, was not compatible with several million existing, convential black and white receivers. Thus, research continued with an eye to development of a color TV tube which would receive conventional black and white programs as well as color programs.

After an extensive research program, RCA finally developed a single picture tube all-electronic color TV receiver. Thousands of phosphor dots in trios of red, green and blue were deposited upon a flat glass plate to form the screen. Three electron guns grouped at slight angles to each other at one end of the tube each produced a beam of electrons to excite phosphors of a given color emanation. To assure that electrons from the “red gun” struck only “red” phosphors, those from the “green gun” struck only “green” phosphors and those from the “blue gun” struck only “blue” phosphors, a thin flat metal sheet having a single perforation for each trio of phosphor dots was interposed between the guns and the phosphor dots. 3 That perforated sheet was called a “shadow mask” because the areas between perforations “shadowed” or shielded all of the phosphor dots of two of the colors from the beam from any gun. The mask and the phosphor dot screen were parallel to each other. In other words, the goal of the red beam striking only red dots, the green beam striking only green dots and the blue beam striking only blue dots was achieved because each beam came through the mask apertures at an angle which permitted it to strike only its associated phosphor dots. This system became the accepted FCC color TV standard in December 1953.

The RCA tube, while commercially acceptable, was not perfect. The major problem with the tube was keeping the shadow mask aligned with the phosphor dot screen. Eighty-five per cent of the electrons emitted by the electron guns *784 hit the metal sheet; only 15% passed through the apertures and hit the screen. The electrons that hit the metal mask heated the mask and caused it to expand. When the mask expanded, the apertures moved, causing the various electron beams to hit the wrong phosphor dots (misregistry). This substantially decreased color fidelity. RCA solved this problem by preheating the mask to operating temperatures and tightly clamping it into a rigid metal frame. 4 When the mask then cooled, it was unable to move and, assuming it was properly aligned in the first instance, the mask was thus in proper alignment when operating during the warm-up cycle as well as when operating at rated temperatures. 5

The above-described solution to the shadow mask alignment problem created difficulties both for the viewer and the manufacturer. Operating the drumhead tube at levels of brightness suitable for viewing in a normally lighted room required the intensity of the electron beams to reach levels so high that the mask was heated above the temperature at which it was tensioned. When such levels were reached, warping occurred and, once again, color fidelity was lost. Even a bright area in a picture being presented could cause localized heating in the mask and resulting areas of color smearing. Moreover, the drumhead tube created a small picture (the RCA commercial tube had a 15 inch viewing screen) for a relatively large tube envelope.

From the standpoint of the manufacturer the tube was unsatisfactory because the heavy internal assembly, or “color sandwich” 6 had to be heated to a high temperature to drive out occluded gases as the necessary vacuum was being drawn within the tube. 7 There was also the added cost of equipment and labor involved in the operation of heating and clamping the mask in its frame.

In the early 1950’s other electronics manufacturers continued experiments to attempt to develop solutions to the picture tube problem. For example, Philco was hard at work developing its code named “Apple” tube which operated on entirely different principles and did not employ a shadow mask at all although the picture was displayed on the face plate of the tube. Another type was the so-called “Lawrence” tube in which the electron beam or beams passed through a grid of parallel wires to be deflected in required directions by circuits which varied the voltage between the grid and the phosphor screen. The Apple and Lawrence tubes never became commercial, and there were also other experimental types which fell by the wayside. 8

III.

THE FYLER AND ROWE SOLUTION

This historical background describes the state of the art in 1953 when CBS developed the tube which embodies the '518 patent in suit. Color fidelity in TV tubes had been a long standing problem in the industry which many major corporations and scientists had attempted to solve.

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391 F. Supp. 780, Counsel Stack Legal Research, https://law.counselstack.com/opinion/columbia-broadcasting-system-inc-v-zenith-radio-corp-ilnd-1975.