Hazeltine Research v. Admiral Corporation

• Decision Date: 22 September 1949
• Docket Number: Civ. A. No. 48C731.
• Citation: 87 F. Supp. 72
• Parties: HAZELTINE RESEARCH, Inc. v. ADMIRAL CORPORATION.
• Court: U.S. District Court — Northern District of Illinois

87 F. Supp. 72

HAZELTINE RESEARCH, Inc. v. ADMIRAL CORPORATION.

Civ. A. No. 48C731.

United States District Court N. D. Illinois, E. D.

September 22, 1949.

M. Hudson Rathburn, Mason, Kolehmainen, Rathburn & Wyss, Chicago, Ill., Laurence B. Dodds, New York City, New York, for plaintiff.

Darby & Darby, New York City, Pope & Ballard, Chicago, Ill., for defendant.

IGOE, District Judge.

Findings of Fact

1. This is a suit for infringement of claims 1, 2 and 4 of patent 2,208,374, Lewis, assigned to Plaintiff, Hazeltine Research,

Inc., a company engaged in research and development in the radio and television field, against Admiral Corporation, a manufacturer of radio and television receivers. The patent in suit is directed to a portion of a broadcast television receiver circuit.

2. Among the problems encountered in broadcasting and reception of television signals are two with which the patent in suit is concerned:

(a) Maintaining the analysis of the image at the transmitter and the synthesis at the receiver in synchronism, that is, in step or in gear. In commercial television broadcasting, as represented schematically in Exh. 4, the analysis of the image at the transmitter and the correlative synthesis at the receiver are effected by cathoderay tubes. Such a tube develops an extremely fine pencil or beam of electrons, known as a cathode ray, which is deflected back and forth across the face of the tube, a process called "scanning". The scanning at the transmitter and at the receiver must be maintained in synchronism so that, at every instant, the cathode ray of the picture tube at the receiver is reconstructing the same portion of the transmitted image as is being analyzed at the camera tube at the transmitter. This synchronism is effected by sending out at the end of each scanning line a synchronizing pulse and at the end of each series of lines, constituting what is termed a field, a different type of synchronizing pulse. These pulses are added to the picture signals at the transmitter and must be separated again at the receiver. For convenience, the term "synchronizing signal" is abbreviated as "sync signal" and "synchronizing-signal separation" as "sync separation" and the device for performing this function is abbreviated as "sync separator". Prior to Lewis' invention, apparatus had been devised for effecting such sync separation at a television receiver.

(b) Maintaining the correct relation between the average brightness or background illumination of the image being transmitted and the average brightness of the image being reproduced at the receiver. The background illumination component of a television signal usually varies slowly and, for convenience, is referred to as the direct-current or "d.c." component of the television signal. For technical reasons the d.c. component is usually discarded in the amplification of the television signal at the receiver and it must thereafter be recovered or "restored" to the signal before it is applied to the picture tube. Prior to Lewis' invention, apparatus had been devised for recovering or restoring the d.c. background illumination component of a television signal for application to the picture tube.

3. The Lewis invention comprises a novel and extremely simple apparatus or circuit for simultaneously performing both of the above-described functions, namely, sync signal separation and d.c. restoration.

4. The Lewis invention is sufficiently described in patent 2,208,374 in suit, and is particularly described with reference to Figs. 1 and 2 of the drawings at page 1, col. 1, lines 5-50; page 2, col. 1, line 30 to page 2, col. 2, line 43; and page 2, col. 2, line 71 to page 3, col. 2, line 27.

5. On August 28, 1937, Lewis filed his patent application Serial No. 161,424 which contained a complete disclosure of the invention illustrated, described and claimed in patent 2,208,374 issuing thereon.

6. In brief, the Lewis invention described and claimed in patent 2,208,374 comprises a combined sync signal separator and d.c. restorer for a television receiver including the following essential elements, the appended references being to the patent drawing:

(a) A signal-translating stage, such as a cathode-ray signal-reproducing or picture tube (cathode-ray tube 17).

(b) A diode (two-electrode) rectifier coupled directly to the input circuit of the stage, i. e., the input circuit of the picture tube, for deriving from an applied video signal a bias voltage proportional to the peak value of the signal (diode rectifier 36 and associated load resister 29 across which the specified bias voltage is developed).

(c) A source of constant bias voltage (battery 39 or equivalent).

(d) A background-illumination control circuit connected to respond jointly to the bias voltage derived from the rectifier and the constant bias voltage (the circuit specified may be traced from the grid 21 of picture tube 17, through resister 29 and battery 39 to ground, and thence from ground to the cathode 20 of the picture tube and the cathode-grid space of that tube).

(e) Impedance means, such as a resistor, connected in circuit with the rectifier for deriving from the applied signal pulses corresponding to the synchronizing pulses (resistor 37 interposed between the anode of the diode rectifier 36 and ground and across which sync pulses are developed).

(f) A scanning synchronizing circuit connected to utilize the synchronizing signals derived by the impedance means (the circuit leading from the top of resistor 37 through condenser 41 to the vacuum tube 40 which amplifies the separated sync signals).

7. The Lewis invention as described has gone into widespread commercial use, having been embodied in approximately 36% of the postwar models of television receivers including the Hazeltine-licensed RCA Model 630 TS receiver.

8. The specification and claims of the Lewis patent fully comply with the provisions of the Patent Statutes and particularly with the statutory requirements of clarity and completeness of disclosure and definiteness of claiming; specifically, claim 2 is not indefinite in its reference to a large capacitance element and a high resistance element since both of these elements were conventional and their selection was well within the skill of a competent engineer.

9. Defendant, at the trial, relied upon three United States patents (together with their corresponding foreign patents containing the same disclosures but having earlier dates of publication) and one British patent. These patents fail to anticipate the Lewis invention for the following reasons:

(a) Patent 2,136,810 — Vance (considered by the Patent Office). The circuit of this patent is a very complex one including a tetrode (i. e. a four-electrode) tube R57 having associated circuit elements for developing a d.c. restoring bias and separated sync signals at different portions of its circuit and an additional triode (i. e. a three-electrode) non-amplifying tube R2A3 which serves only to reverse the polarity of the video signal applied to the picture tube and is thus effectively wasted since it performs no amplification. This complex circuit including two separate tubes, a triode and tetrode, and a great many circuit elements accomplishes generally the same purpose as the Lewis single diode (i. e. two-electrode) tube, which is really only one-half of a tube envelope as embodied in the Admiral receiver, and very few circuit elements.

The following features of the Lewis claims are not found in the Vance disclosure:

(1) A diode (two-electrode) sync separator and d.c. restorer. The Vance circuit requires both tetrode (four-electrode) and triode (three-electrode) vacuum tubes and a complex circuit for accomplishing a purpose similar to Lewis.

(2) A connection of the diode rectifier directly to the input circuit of the picture tube so that the value of the d.c. restoring bias is at all times inherently of the proper value to effect correct d.c. restoration. In Vance it is necessary to interpose a non-amplifying polarity-reversing tube R2A3 between the input circuit of the d.c. restoring tube R57 and the picture tube, which not only increases the complexity of the circuit but requires continuous and critical adjustment; that is, the input circuit of the Vance d.c. restoring tube R57 is connected to the input circuit of the picture tube indirectly through the polarity-reversing tube R2A3.

(b) Patent 2,151,149 — Poch (corresponds to Australian patent 100,910). This patent describes a sync separator circuit comprising a diode rectifier tube 18 having a series resistor R2 which performs generally the sync separating function of Lewis' diode rectifier 36 and series resistor 37 but which differs from Lewis in several important respects. Defendant's expert admitted that the following three elements of the Lewis claims were not disclosed in the Poch patents:

(1) A source of bias voltage associated with the sync separator diode in addition to the bias voltage developed by the diode.

(2) A signal-reproducing device (picture tube) with input electrodes coupled directly to the diode load resistor.

(3) Means for utilizing the bias voltage developed by the rectifier for restoring the d.c. components (background illumination) of the video signal.

While the Poch patent was not considered by the Patent Office, its disclosure, so far as material here, is similar to that of British patent 453,463 which was considered by the Patent Office.

(c) Patent 2,252,746 — Willans (corresponds to British patent 422,906 considered by the Patent Office). Figure 10 of this patent was the only one discussed as allegedly pertinent to the Lewis invention. That figure discloses a diode d.c. restorer circuit quite similar to that of the Lewis patent, but it does not disclose any apparatus for obtaining sync separation. The Willans patent was considered by Defendant's expert to have the disclosure closest to that of the Lewis patent.

(d) British...