Case Comment

Philco Products Limited and Cutten-Foster & Sons, Limited

v. Thermionics Limited et al.


citation(s): [1943] S.C.R. 396 (per Taschereau, J.) at pp. 412-413


copyright 1997 Donald M. Cameron, Aird & Berlis




The Decision

At p. 412:

"Of course, I am not forgetful, and I have kept in mind that what is claimed here is a combination. The combination of known contrivances may be the proper subject matter of a patent, but, it has to achieve a combined result, which is the novelty. In the Langmuir patent, with respect, I see nothing of the kind. The co-acting parts described in the patent were before used together for all the purposes mentioned in the claims. The high voltage which is claimed as the result of this combination, is not to my mind a statement based on the evidence. Dr. Chaffee, expert witness for the appellants, comes to the conclusion, and Dr. Hogan, called by the respondents, practically corroborates this assertion, that if properly evacuated the Deforest tube could be used at high voltages. The converse is also true, and if improperly evacuated the Langmuir tube would lose its virtue. It is the first Langmuir patent of 1920 that achieved the result of allowing such high voltages to be obtained, and I cannot sustain this patent in suit, unless I import from the expired patent what was its subject-matter. I believe that this Langmuir patent is invalid."

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