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, 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.
[Page 225]
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.
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