Armstrong v. De Forest Radio Telephone & Telegraph Co.

• Citation: 279 F. 445
• Parties: ARMSTRONG et al. v. DE FOREST RADIO TELEPHONE & TELEGRAPH CO.
• Decision Date: 17 May 1921
• Court: U.S. District Court — Southern District of New York

279 F. 445

ARMSTRONG et al. v. DE FOREST RADIO TELEPHONE & TELEGRAPH CO.

United States District Court, S.D. New York.

May 17, 1921

Pennie, Davis, Marvin & Edmonds, of New York City (Thomas Ewing, William H. Davis, W. Brown Morton, Drury W. Cooper and Willis H. Taylor, Jr., all of New York City, of counsel) for plaintiffs.

Darby &amp Darby, of New York City (Samuel E. Darby, Jr., of New York City, of counsel), for defendant.

Charles Neave and William R. Ballard, both of New York City, for American Telephone & Telegraph Co., as amicus curiae.

MAYER District Judge.

This is a suit of major importance. It concerns an invention of high merit, and the cause has been presented ably and comprehensively. While the record is voluminous, it differs from some long records in that, by reason of the issues of fact involved, its length is fully justified. The defenses are many, but the principal attacks are directed against the priority of Armstrong. It is claimed for Armstrong that his date of invention is at least as early as January 31, 1913, and thus antedates Schloemilch and Von Bronk, infra, Meissner, infra, and De Forest, infra. Before discussing the questions involved in the priority contest, it is desirable to ascertain what the patent is and what is its accomplishment.

At the outset, it should be stated that the Armstrong feed-back circuit, as it has come to be known familiarly, must be recognized as a contribution of marked value to the practical art. Its employment has so greatly increased both the loudness and the definition of the sounds heard in the receiver that long-distance radio communication has been remarkably improved and thus greater reliability has been attained.

'The present invention,' Armstrong stated in his specification, 'relates to improvements in the arrangement and connections of electrical apparatus at the receiving station of a wireless system, and particularly a system of this kind in which a so-called 'audion' is used as the Hertzian wave detector; the object being to amplify the effect of the received waves upon the current in the telephone or other receiving circuit, to increase the loudness and definition of the sounds in the telephone or other receiver, whereby more reliable communication may be established, or a great distance of transmission becomes possible. To this end I have modified and improved upon the arrangement of the receiving circuits in a manner which will appear fully from the following description, taken in connection with the accompanying drawings. As a preliminary, it is to be noted that my improved arrangement corresponds with the ordinary arrangement of circuits in connection with an audion detector to the extent that it comprises two interlinked circuits, a tuned receiving circuit in which the audion grid is included, and which will be hereinafter referred to as the 'tuned grid circuit,' and a circuit including a battery or other source of direct current and the 'wing' of the audion, and which will be hereinafter referred to as the 'wing circuit.' As is usual, the two circuits are interlinked by connecting the hot filament of the audion to the point of junction of the tuned grid circuit and the wing circuit. I depart, however, from the customary arrangement of these circuits in a manner which may, for convenience of description, be classified by analysis under three heads: Firstly, the provision of means or the arrangement of the apparatus, to impart resonance to the wing circuit, so that it is capable of sustaining oscillations corresponding to the oscillations in the tuned grid circuit; secondly, the provision of means supplementing the electrostatic coupling of the audion to facilitate the transfer of energy from the wing circuit to the grid circuit, thereby reinforcing the high frequency oscillations in the grid circuit; and, thirdly, the introduction into the wing circuit of an inductance through which the direct current of the wing circuit flows, and which is so related to the grid circuit that the maintaining electromotive force across the terminals of the inductance, due to reduction of the direct current, is effective in the tuned grid circuit to increase the grid charge, and consequently to further reduce the current in the wing circuit and in the telephones.'

The 'firstly' and 'thirdly,' supra, were in the original specification; the 'secondly' was inserted during the prosecution of the patent application. The first statement is illustrated in the drawings of the patent, Figs. 1, 2, 3, and 6. An illustrative claim is No. 1, which specifies, inter alia, 'a resonant wing circuit' and reads as follows:

'1. An audion wireless receiving system having a resonant wing circuit interlinked with a resonant grid circuit upon which the received oscillations are impressed, the resonant grid circuit having a capacity so related to the grid as to receive and retain the charge which accumulates thereon.'

The second statement, which defines broadly the instrumentalities of the first and third statements, is represented by each of the figures of the patent drawings and illustrated by claim 9, which reads as follows:

'9. An audion wireless receiving system having a wing circuit interlinked with a resonant grid circuit upon which the received oscillations are impressed, and an inductance through which the current in the wing circuit flows, the grid circuit including connections for making effective upon that circuit the potential variations resulting from a change of current in the wing circuit.'

The third statement is illustrated in the drawings of the patent, Figs. 1, 2, 4, 5, and 6. In one form of language or another, what is set forth in the third statement is embodied in claims 3, 5, 8, 12, 14, and 17. Claim 17 will suffice for illustration:

'17. An audion wireless receiving system having a wing circuit interlinked with a resonant grid circuit upon which received oscillations are impressed and an electrostatic coupling between the circuits supplementing the coupling of the audion to facilitate transfer of energy from the wing circuit to the grid circuit, whereby the effect upon the grid of high frequency pulsations in the wing circuit is increased.'

For so difficult a subject-matter, the specification and claims as originally filed fared very well in the Patent Office. The first 14 claims were allowed as filed, and they constitute all of the original claims, except one originally numbered 13, which was rejected on reference to the Schloemilch and Von Bronk patent. The amendments to the specification (page 1, lines 56-60; page 2, lines 47-54; page 3, lines 33-47) and the amendment to the claims by way of addition of claims 15-18, inclusive, were concerned only with statement of the mode of operation, and did not add to the instrumentality described and claimed in the original application and drawings. Out of the mass of testimony and argument, too extensive to quote or to discuss in complete detail, it is well to settle one proposition at the start.

The Armstrong specification and claims show that the invention was for an instrumentality. The feed-back circuit was well defined in the record on a number of occasions. Professor Hazeltine, plaintiff's expert, stated that the fundamental principle of Armstrong's invention was:

'The provision of an arrangement for transferring oscillating current energy from the plate circuit to the grid circuit whereby oscillations present in the grid circuit are assisted. ' Answer to XQ39.

'Any arrangement by which oscillating current energy is transferred from the output or plate circuit of the audion to the input or grid circuit to sustain the oscillations in the grid circuit is included in the principle of the Armstrong invention. ' Answer to XQ41.

Defendant asserts that the question is whether the invention resides in the reamplifying audion or in the oscillating audion or in both or in 'some more basic idea,' and then contends that the patent is limited by its own terms to the reamplifying audion.

The amicus curiae, through its counsel, put forward substantially the same contention, urging that the Armstrong disclosure was nothing more than the use of the audion for reamplifying purposes.

All of these arguments and all the analysis of the Armstrong patent language and claims come down to a single proposition: If Armstrong invented a new instrumentality, he is entitled to the fruits of all its uses, whether he understood them or not, and whether his theory of operation was right or wrong, comprehensive or limited. Given the new instrumentality, the question is what it does, not how or why it does something. It is urged that the error of the argument for Armstrong is--

'primarily in the assumption that the invention is a specific recognizable thing called a 'feed-back,' a definite group of mechanical or electrical elements which like a tool may be used for various purposes. That is not the invention. The invention is * * * a particular use of an otherwise old circuit by an adjustment of the constants so as to produce reamplification.'

The discussion of the limitations upon the patent by its own terms includes quotations from the patent at those places where Armstrong pointed out that, if the ratio of feed-back coupling exceeded a certain amount, the audion would become a high frequency generator, setting up disturbing oscillations in the grid and wing circuits, and informed the art how maximum amplification of damped wave signals could be obtained below oscillation. See particularly page 4, lines 51-77. But, the fact is that defendant's oscillating audion does regeneratively feed back energy from the plate circuit to the grid circuit to amplify cumulatively the received signals. This seems satisfactorily...