Hazeltine Corp. v. General Motors Corp.

38 F. Supp. 880, 49 U.S.P.Q. (BNA) 523, 1941 U.S. Dist. LEXIS 3357
CourtDistrict Court, D. Delaware
DecidedMay 8, 1941
DocketNo. 1260
StatusPublished
Cited by1 cases

This text of 38 F. Supp. 880 (Hazeltine Corp. v. General Motors Corp.) is published on Counsel Stack Legal Research, covering District Court, D. Delaware primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Hazeltine Corp. v. General Motors Corp., 38 F. Supp. 880, 49 U.S.P.Q. (BNA) 523, 1941 U.S. Dist. LEXIS 3357 (D. Del. 1941).

Opinion

NIELDS, District Judge.

This is the usual patent infringement suit. It charges infringement of U. S. Patent No. 2,111,483 issued March 15, 1938, to Carl E. Trube, assignor to Hazeltine Corporation, upon application filed July 2, 1926. Suit was brought April 19, 1938, thirty-five days after the issuance of the patent. The defenses are invalidity and noninfringement.

The claims originally in suit as specified in plaintiff’s bill of particulars were numbers 1 to 4, inclusive; 12 to 22, inclusive, and 28 to 38, inclusive. At the trial plaintiff withdrew all but claims 28 to 33, inclusive, and 35 to 38, inclusive. Claims 31 and 36 were selected as typical:

“31. The method of transferring electrical energy throughout a range of frequencies from an exciting circuit to a tunable absorbing circuit, which consists of transferring the energy both electromagnetically and electrostatically in aiding phase, and causing said electrostatic transfer to vary in a preselected manner as said absorbing circuit is tuned.”

“36. A tunable radio-frequency coupling system comprising a resonant circuit including inductive and capacitive elements, only one of said elements being adjustable for tuning said circuit over a wide range of radio frequencies, another circuit to be coupled therewith, fixed reactance coupling means including inductance for providing coupling therebetween which varies with frequency in one sense as said tunable circuit is tuned over said range, and fixed reactance' coupling means including capacitance for providing coupling therebetween which varies with frequency in the opposite sense, said coupling means being relatively poled in aiding phase, whereby the coupling variation of one said means at least partially compensates for the coupling variation of the other said means.”

Plaintiff consents that the final judgment shall contain a provision that the com[881]*881plaint be dismissed as to all claims thus withdrawn. Hence only ten claims remain of the twenty-six originally in suit. The accused structures are automobile radio receiving sets manufactured and sold by defendant. Early in the litigation defendant voluntarily furnished plaintiff complete circuit diagrams of all its automobile receivers manufactured or sold during the thirty-five day period with which this litigation is concerned. These comprise nineteen different models. The accused coupling systems in defendant’s broadcast receiving sets, here submitted for adjudication, are four in number:

1. The coupling system between the antenna circuit and the first adjustably-tunable selective circuit in the Buick receiving set model 1,304,873, Serial No. 336,483.

2. The interstage coupling system between the plate circuit of the first amplifier tube and the second adjustably-tunable selective circuit in the same Buick set.

3. The like interstage coupling system in the Chevrolet set model 985,253, Serial No. C1001.

4. The coupling system between the plate circuit and the adjustably-tunable Lsonant circuit connected to the grid of the heterodyne oscillator tube of the Chevrolet set.

Invalidity.

The patent in suit is invalid for lack of invention.

The patent is directed simply to the use of two old coupling instrumentalities at the same time. The patent states that Figure 4, the preferred form, is simply the combination of magnetic coupling only with capacity coupling only. Both kinds of coupling, both separately and together, were old long prior to Trube in certain radio receiving sets. No invention was required to use both the practically available types of coupling at the same time, each old and each giving, independently of the other, its own well-known effect. All that was wanted was the sum of the individual effects. There was nothing novel or surprising in having the two kinds of coupling aid for greatest amplification.

The patent commences by saying that the alleged invention “relates to electric coupling systems particularly adapted for use with radio-frequency vacuum tube amplifiers”. The only vacuum tubes described in the patent are of the “triode” type. Each comprises a grid, a plate and a filament. The physical proximity of the grid to the plate produces a substantial condenser. The high electrical pressure in the plate circuit caused a feedback through this grid-to-plate capacity of the tube. Such feedback produced regeneration. The energy was amplified and re-amplified by passing more than once through the tube which, if not controlled, might produce oscillations resulting in squeals, whistles and other undesirable noises.

To reduce the effects of such feedback, various systems of neutralization were proposed. They consisted in producing a neutralizing feedback from the plate circuit to the grid circuit, outside the tube. Two of these systems were those of Hartley and Rice, whose patents were sustained. A later one was that of Professor Hazeltine in the neutrodynes. His patents were also sustained. When Professor Hazeltine’s “neutrodyne” patents were sustained, there came a reason for the use of a “double coupling”. Trube, Wheeler and many other radio designers and engineers in different parts of the country, independently and almost simultaneously, applied the double coupling in order to avoid the Hazel-tine patents. Hazeltine himself worked on double coupling about the same time.

Trube sought to develop an alternative way of overcoming the same effects of the grid-to-plate capacity feedback existing in the triodes. His object was to develop a radio receiver which would be highly sensitive and highly selective and also stable without neutralization and without infringing Professor Hazeltine’s patents.

Trube was at that time a very young and inexperienced man, a few years out of college, and went to his former teacher, Professor Hazeltine, for help in preparing his patent application. Professor Plazeltine, an experienced mathematician, helped Trube in working out a scientific explanation of the simple facts which Trube had observed.

Only two kinds of coupling were practically available — magnetic and capacity. Magnetic gave an amplification which increased too fast. Capacity gave one which decreased too fast. Trube’s whole patent, as regards the claims now remaining in suit, uses both kinds of coupling together to average up the results of using each by itself. Under whatever formula of scientific sounding words, it is still no more than the simultaneous use of two kinds of coupling, which were previously known and used both individually and together, for the [882]*882identical purpose of getting the “algebraic sum” of their several effects. There is no evidence that Trube had any difficulty in combining the two things, or in deciding to try the double coupling. There is lack of invention when it is shown that the same idea occurred independently, about the same time, to ten or a dozen different engineers or designers, both before and after Trube’s filing date.

The “difficulty” arose out of the fact that the patents of Hazeltine, Hartley and Rice were barring the way to the use of anything that neutralized the feedback. The whole art with one accord went to “double coupling” which'would avoid the creation of feedback sufficient to cause oscillation of a “triode”. In other words, to avoid the Hazeltine patents, Trube and a host of others hit upon a noninfringing means embodying the “double coupling” idea for accomplishing the same result as the neutrodyne.

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Bluebook (online)
38 F. Supp. 880, 49 U.S.P.Q. (BNA) 523, 1941 U.S. Dist. LEXIS 3357, Counsel Stack Legal Research, https://law.counselstack.com/opinion/hazeltine-corp-v-general-motors-corp-ded-1941.