Supreme Court of Canada
Northern Electric Co. Ltd. v. Brown's Theatres Ltd., [1941] S.C.R. 224
Date: 1941-02-04
Northern Electric Company, Limited, and Western Electric Company, Inc. (Plaintiffs) Appellants;
and
Brown's Theatres Limited (Defendant) Respondent.
Brown's Theatres Limited (Defendant) Appellant;
and
Northern Electric Company, Limited, and Western Electric Company, Inc. (Plaintiffs) Respondents.
1940: May 21, 22: 1941: February 4.
Present: Duff C.J. and Crocket, Davis, Kerwin and Hudson JJ.
ON APPEAL FROM THE EXCHEQUER COURT OF CANADA
Patents—Validity—Subject-matter—Infringement.
An appeal by the plaintiffs from the judgment of Maclean J., [1940] Ex. C.R. 36, in so far as that judgment dismissed their action in respect of alleged infringement by defendant of Canadian patent 333,478 (granted on petition of one Miller for an alleged new and useful improvement in Sound Reproducing Systems), and an appeal by the defendant from said judgment in so far as it granted relief to the plaintiffs in respect of alleged infringement by defendant of Canadian patent 218,931 (granted on petition of one Wilson for an alleged new and useful improvement in Electron Discharge Devices), were both dismissed.
APPEAL by the plaintiffs from the judgment of Maclean J., President of the Exchequer Court of Canada[1], in so far as that judgment dismissed their action in respect of alleged infringement by defendant of Canadian patent 333,478 granted on the petition of one Miller for an alleged new and useful improvement in Sound Reproducing Systems; and APPEAL by the defendant from the said judgment in so far as it granted relief to the plaintiffs in respect of alleged infringement by defendant of Canadian patent 218,931 granted on the petition of one Wilson for an alleged new and useful improvement in Electron Discharge Devices.
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The said appeals were consolidated by an order in this Court. Both said appeals were dismissed with costs.
O. M. Biggar K.C. and R. S. Smart K.C. for the plaintiffs (appellants in one appeal and respondents in the other).
H. N. Chauvin K.C. and F. B. Chauvin for the defendant (respondent in one appeal and appellant in the other).
The judgment of the Court was delivered by
The Chief Justice—The appeal of the plaintiff companies concerns a patent granted to one, Miller, on the 20th of June, 1933, and the defendant company's appeal concerns a patent granted to one, Wilson, on the 23rd of May, 1922. I have reached the conclusion that both appeals should be dismissed with costs.
First, of Wilson's patent. Some years before the date of this patent it had come to be recognized that in the operation of vacuum tubes in signal receiving apparatus there are very important advantages in maintaining a negative bias upon the grid. There were different ways of doing this, those commonly used in such apparatus at that period being, (1) by connecting the grid with a separate source of negative potential, and (2) by inserting a resistance in the filament heating circuit and applying the drop of potential thus obtained to the grid. Wilson conceived the idea of imparting the negative bias to the grid by availing himself of the plate circuit. The advantages of this will be referred to later. There was a possible disadvantage against which provision had to be made; a disadvantage so great that if means were not found for surmounting it, it would be prohibitive. The disadvantage was this: If the rapid signal variations in the plate current were repeatedly impressed upon the grid, interference and loss of control would almost certainly result. It was essential to avoid this.
Wilson's invention consists in the idea of resorting to the plate circuit for the source of negative potential for the grid with the provision of means for meeting the practical objection that to allow the rapid variations in the plate current to be imposed upon the grid at this stage would be inadmissible. He solved this by providing
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separate paths for the two components of the plate current (the rapid signal variations component and the steady component) and connecting the grid with that part of the circuit not traversed by the rapidly fluctuating signal variations component. Wilson states in his specification that his invention provides a valuable improvement in vacuum tubes used in signal reception apparatus because it provides compensation against what he describes as "the contact difference in potential between grid and cathode." Apparently, by reason of advances made toward perfecting the manufacture of vacuum tubes, this advantage of Wilson's invention has become obsolete. But it is said that by deriving the biasing potential from the steady component of the plate current, compensation is provided for slow changes in that current and this results in a uniformity of the operation of the tube which is not secured when the potential is derived from a special battery, or from the filament heating circuit. This is explained in the evidence of the plaintiffs' witness, Stevenson, at page 64 of the Appeal Case:—
Q. * * * What about variations in strength of the battery itself? A. If the strength of that current, the steady current, changes for any reason, it will produce a proportionate change in the bias potential and it will produce it in such a sense as to oppose the change itself.
Q. With what result? A. With the result that the change is diminished.
In support of the contention that Wilson's invention had been anticipated, two patents are referred to, that of Mathes and that of Langmuir.
Mathes' arrangement bears some resemblance to that of Wilson's; his output circuit is so arranged as to separate the fluctuating signal component from the steady component of the plate current, but at the trial it was not disputed that approximately ninety-nine per cent of the negative potential supplied to the grid is obtained from the filament battery.
As to Langmuir, his invention had nothing to do with wireless receiving sets. Langmuir derives the negative potential for the grid from the plate circuit, but he was not concerned with the question with which Wilson had to deal, namely, the diversion of the fluctuating signal
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component of the plate current in such manner as to avoid impressing a second time the signal impulses upon the plate filament current.
I think neither Langmuir's device, nor Mathes' device, constitutes anticipation of Wilson's invention.
I have, I must say, been much concerned with the question whether Wilson's combination exhibits subject-matter. The means by which he provides separate paths for the two components of the plate current cannot, in themselves, be said to possess patentable novelty, as the learned President of the Exchequer Court points out, but the idea of providing separate paths for these components in order to obtain from the steady component of the plate filament current the negative potential requisite for biasing the grid was new and it seems, moreover, to have constituted a valuable improvement. I repeat, I have had a good deal of doubt on the point, but this much is certain, I am not sufficiently clear in my own mind that subject-matter is absent to justify the conclusion that the finding of the learned President in the opposite sense should be set aside.
There remains the question of infringement. The learned trial judge has found that Wilson's invention has been substantially taken. Once again, I can only say I think the point is a very arguable one, but I am not satisfied that the judgment of the learned President of the Exchequer Court can properly be reversed.
As to the Miller patent, I think the learned President arrived at the right conclusion; and I do not think it necessary to add anything to his reasons, with which I agree.
Appeal by plaintiff and appeal by defendant both dismissed with costs.
Solicitors for the plaintiffs (appellants in one appeal and respondents in the other): Smart & Biggar.
Solicitors for the defendant (respondent in one appeal and appellant in the other): Chauvin, Walker, Stewart & Martineau.