Hazeltine Corp. v. Electric Service Engineering Corp.

• Decision Date: 01 July 1926
• Citation: 18 F.2d 662
• Parties: HAZELTINE CORPORATION et al. v. ELECTRIC SERVICE ENGINEERING CORPORATION.
• Court: U.S. District Court — Southern District of New York

18 F.2d 662 (1926)

HAZELTINE CORPORATION et al. v. ELECTRIC SERVICE ENGINEERING CORPORATION.

District Court, S. D. New York.

July 1, 1926.

Pennie, Davis, Marvin & Edmonds, of New York City (William H. Davis and Willis H. Taylor, Jr., both of New York City, of counsel), for plaintiffs.

Leonard Day, of New York City (William L. Morris, of New York City, of counsel), for defendant.

THACHER, District Judge (after stating the facts as above).

The Hazeltine method of neutralizing capacity coupling between two electrical circuits relates primarily to the art of radio reception, although the claims of his first patent are not confined to use in this field. The development of this art by Fleming, De Forest, and Armstrong is shown in Marconi Wireless T. Co. v. De Forest Radio T. & T. Co. (C. C. A.) 243 F. 560, and Armstrong v. De Forest Radio Telephone & Tel. Co. (C. C. A.) 280 F. 584. The use of the audion as a detector by Fleming, its perfection by De Forest, and its employment by Armstrong in his regenerative feedback system of amplification, presented a new problem, because the audion itself, under the influence of regenerative amplification, was converted into an independent generator of continuous oscillations. These oscillations produced in the receiving instrument "squeals," "howls," and "whistles," which drowned out the incoming signal.

The cause of these unwelcome disturbances was the capacity coupling between the primary and secondary circuits of the radio receiver and between the plate and grid circuits of the audion. By neutralizing the currents flowing through these capacity couplings, Hazeltine succeeded in eliminating the oscillating disturbances. This he accomplished by arranging an auxiliary circuit, so associated with the plate and grid circuits, through capacity coupling with one and electromagnetic coupling with the other, that the magnetic effect of the current in the auxiliary circuit completely and permanently neutralized the disturbing voltages resulting from the capacity coupling between the two circuits. The utility of his accomplishment is demonstrated by the extraordinary commercial success of the neutrodyne receiving sets manufactured and sold under license from the plaintiff. Five per cent. royalties paid under such licenses from April 1, 1923, to September 30, 1925, amounted to $1,161,103.30. For the three months ending December 31, 1924, those royalties amounted to $378,730.54.

In support of the defense of priority of invention, and to show the state of the prior art, reference is made in the pleadings and proofs to several prior patents. Of these the patents to Alexanderson, August 12, 1919, No. 1,313,042, to Rice, March 16, 1920, No. 1,334,118, and to Goldsmith and Weinberger, November 8, 1921, No. 1,396,571, were all issued after the date of Hazeltine's invention; the filing date of the application upon which his first patent issued being August 7, 1919. These three patents are not, therefore, in the prior art, and are material only if, from their disclosures, whether claimed or unclaimed, it appears that Hazeltine was not the first inventor of the inventions claimed in the patents in suit. Alexander Milburn Co. v. Davis-Bournonville Co., 270 U. S. 390, 46 S. Ct. 324, 70 L. Ed. 651.

Of these patents Rice more nearly approaches anticipation than any of the others. His objective was the same as Hazeltine's, "to avoid the undesired production of oscillatory currents," which he said "is due to the coupling which is always present between the grid and plate circuits." He proposed to neutralize the electromagnetic coupling between the circuits by a second electromagnetic coupling in the opposite direction, and then states: "This coupling may also be made great enough to compensate for the capacity coupling, but in case it is so arranged it will be correct only for one particular frequency, and in case the tuning of either of the circuits is varied the degree of the coupling also will have to be varied."

Permanent neutralization of capacity coupling for all frequencies, without variation of "the degree of coupling," was neither accomplished nor claimed by him. This Hazeltine did accomplish by closely and permanently coupling the auxiliary coil with the coil with which it is coupled in the other circuit, and by permanently adjusting the ratio of the neutralizing and coupling capacities in the two circuits, so as to equal the inverse ratio of turns on the coils with which they are associated. This adjustment is accomplished by means of a neutralizing capacity, constructed so that it can be delicately adjusted and soldered in place after the individual receiving set has been completely built and is ready for shipment. If the adjustment is properly made, as it can easily be, the capacity coupling remains completely neutralized, until some change is made either in the grid or plate circuit. This permanent and complete neutralization of the neutrodyne receiving sets before sale to the consumer explains the commercial success of these instruments, which is so strongly persuasive of invention.

Rice employed a fixed ratio of equal capacities and equal turns, and arranged his coils with loose coupling. Hazeltine provided close coupling between the coils and unequal turns, with capacities in the ratio stated, and attained permanent neutralization for all frequencies, a result never attained before, and one which had, as the evidence discloses, an astounding effect upon the entire industry. In Electrical Signal Co. v. Hall Signal Co., 114 U. S. 87, 5 S. Ct. 1069, 29 L. Ed. 96, in comparing a patented signaling apparatus for railroads with an alleged infringing apparatus, it is said: "One plan proceeds upon the idea of unequal circuits, to be afterwards equalized; the other adopts and embodies the idea of avoiding the necessity of subsequent rectification by an original adjustment of equal resistances. The difference is inherent in the two combinations and is substantial."

Here the difference between Hazeltine and those who preceded him is much the same, and is of the most essential importance from a functional standpoint and of extraordinary commercial value. Rice and Hazeltine were not very far apart, but the difference between them is the difference between success and failure. I accept the following statement of Professor Pupin in regard to these differences:

"In the Rice patent, the electromagnetic coupling between the two halves of the coil 4 is not even mentioned. In the Hazeltine application the coupling is stated to be `close' and is indicated in the mathematical portions of the application to be 100 per cent. Hence the neutralization of capacity coupling and the consequent elimination of feedback action aimed at by both inventors will be produced by Hazeltine alone. Rice secures only partial neutralization when he produces any at all; whereas, with the `close' coupling of the Hazeltine arrangement, the added capacity C2 can be adjusted once for all to give neutralization which is not disturbed by adjustments of the circuits.

"Since Rice eliminates the feedback action only partially, when he eliminates it at all, it is obvious that oscillation of the vacuum tube will cease to be prevented as soon as the amplifying power passes beyond a certain definite lower limit; whereas Hazeltine, with complete neutralization of capacity coupling, may carry the amplifying power to any practicable extent without producing feedback action. Hazeltine also shows an arrangement, not present in the Rice device, which is apparent from even a most superficial examination — Figure 2 of the application. In this figure we have a coupling capacity between the grid and a coil electromagnetically coupled to a coil in the plate circuit — an arrangement which under certain conditions offers substantial advantages and which is not even suggested in the Rice patent."

This statement was made with particular reference to the second Hazeltine patent. Except with regard to 100 per cent. coupling, it applies to the first as well.

There is nothing in the Alexanderson patent, or the Goldsmith and Weinberger patent, which anticipates Hazeltine. Alexanderson's object was to provide means for neutralizing the effect of radio frequency waves transmitted from a duplex transmission and reception station upon reception apparatus at the same station. He describes his invention as follows: "In order to overcome the effect in the receiving apparatus of the waves impressed upon the receiving antenna from the transmitting antenna, I derive from the transmitting antenna, an electromotive force equal in value and opposite in direction to the potential induced upon the receiving antenna from the transmitting antenna, and impress this electromotive force upon the receiving circuit in such a manner as to neutralize in the receiving apparatus the effect of the induced potential."

Goldsmith and Weinberger had the same objective; i. e., to eliminate the interference in the receiving apparatus capacitively induced by the operation of the transmitting apparatus. This problem was not unlike the problem which confronted Rice and Hazeltine, although in a different field, and the means employed for solution are not in all respects entirely dissimilar. A certain similarity of method was necessarily inherent in their inventions, because they were all concerned with the same forces and presumably guided by the same knowledge of the physical laws governing those forces.

Statutory law is not concerned with the laws and processes of nature, which govern the operations of electrical forces, but with the visible and tangible means and methods humanly devised to control and employ those forces for useful purpose. Marconi Wireless T. Co. v. De Forest Radio T. & T. Co. (C. C. A.) ...