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U.S. Supreme Court

DeForest Radio Co. v. General Electric Co., 283 U.S. 664 (1931)

DeForest Radio Co. v. General Electric Co.

No. 630

Argued May 1, 4, 1931

Decided May 25, 1931

283 U.S. 664


1. Patent No. 1,558,436, to Langmuir, for a high-vacuum discharge tube, used as a detector and as an amplifier in radio communication and telephony, and for the process of making it, held invalid for want of invention and because of prior use. Pp. 283 U. S. 676, 283 U. S. 678, 283 U. S. 682.

The tube in question corresponds structurally with earlier low-vacuum tubes used as detectors and amplifiers, and, as a device or product, its only essential difference from them is in its higher vacuum, produced in the course of manufacture by mechanical exhaustion aided by heat and electronic bombardment. In consequence of this removal of gas, the tube is not subject to the gas-ionization which renders the other tubes uncertain and inefficient, especially when they are used as amplifiers, but is capable, within its limits, of producing a stable discharge when operated at a fixed voltage, and will operate at much higher voltages than the earlier tubes. This tube is an important improvement over the earlier ones, but the patent cannot be sustained, because, as the District Court found and as the evidence shows, the process for creating high vacua in tubes was well known and practised in the art, and the fact that the ill effects of ionization in such electric discharge devices could be removed by increase of vacuum was so known and disclosed in science that the application of that means for improving the earlier devices involved not invention, but only the expected skill of the art.

2. The question is not whether the prior art had made a practicable high-vacuum tube, but whether it showed how one could be made, and demonstrated and disclosed the relationship of the discharge to the reduced pressure. P. 283 U. S. 682.

3. The evidence does not establish that the flow of current is due, in a low-vacuum tube, to the conductivity of ionized gas, and, in a high-vacuum tube, to something else -- pure electron discharge; nor does it appear that the patentee thought there was such a distinction, or relied upon it to remove ionization effects, rather than upon the simple expedient of removing the gas known to be responsible for them. P. 283 U. S. 684. chanrobles.com-red

Page 283 U. S. 665

4. A scientific explanation of a known method and device is not patentable. P. 283 U. S. 684.

5. Value and general use of a device cannot sustain a patent if the lack of invention is clear. P. 283 U. S. 685.

6. The resort to the high-vacuum tube of the patent, and its present utility, are explained as the natural development of a new art through the adaptation to it of scientific knowledge that had been accumulated through investigation and experiment. Id.

7. The prior use of an invention that will invalidate a patent need not have been accompanied by knowledge of the scientific principles involved in the invention. P. 283 U. S. 686.

4 F.2d 931 reversed.

Certiorari, 282 U.S. 836, to review a decree holding a patent valid and infringed and reversing a decree of the district court, 23 F.2d 698, which had dismissed the bill upon the grounds of want of invention, prior invention, and prior use. The court below, by an unreported per curiam opinion of October 3, 1929, had at first affirmed the dismissal upon the opinion of the district judge. The contrary decree here under review was rendered after a reargument. chanrobles.com-red

Page 283 U. S. 669


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