Aerovox Corporation v. Concourse Electric Co.

• Decision Date: 15 May 1933
• Docket Number: No. 395.,395.
• Citation: 65 F.2d 386
• Parties: AEROVOX CORPORATION v. CONCOURSE ELECTRIC CO., Inc.
• Court: U.S. Court of Appeals — Second Circuit

65 F.2d 386 (1933)

AEROVOX CORPORATION v. CONCOURSE ELECTRIC CO., Inc.

No. 395.

Circuit Court of Appeals, Second Circuit.

May 15, 1933.

Dean, Fairbank, Hirsch & Foster, of New York City (Morris Hirsch and F. J. Foster, both of New York City, of counsel), for appellant.

Albert Lavenburg, of New York City (Paul Kolisch, of New York City, of counsel), for appellee.

Before L. HAND, SWAN, and CHASE, Circuit Judges.

L. HAND, Circuit Judge.

This is the usual bill in equity for the infringement of two patents, each concerned with a dry electrolytic condenser for use in radio receiving sets. The first is for a new form of cell; the second for the electrolyte to be used in it. A few words of general explanation are necessary at the start. An electric condenser is a device by which excesses of current are stored and released, acting as a sort of elastic cushion for its variations. It is made up of two electrodes, anode and cathode, separated by a non-conductor, the dielectric. The capacity of the condenser depends upon the dielectric, and varies inversely with its thickness. It had long been known that an excessively thin film on the anode, or positive electrode, was the optimum dielectric. Various metals had been used for the purpose; aluminum, the metal chosen in the patents, was well-known; the film was made by passing an electric current across the electrodes in a bath made up of a solution, which was known as the electrolyte. This was called "the forming process." When complete, the anode with its dielectric film was ready for use and with the cathode made the condenser. However, in use the dielectric degenerates; moreover, it is subject to puncture, if the voltage becomes to great for its tolerance and the condenser then becomes useless, unless restored. Thus it was necessary that in use an electrolyte should be present both to preserve the dielectric and to restore it in case of rupture. In a wet condenser the electrolyte is a bath of proper solution in which both electrodes are immersed, the solution being in effect part of the cathode. In a dry condenser the electrolyte is absorbed by a gauze interposed between the cathode and the dielectric. The two patents concern such a condenser; the first relates to its make-up, the second to the electrolyte. We will first take up the "structure" patent.

As we have just said, the art of dry condensers had before the application been familiar with a gauze between the electrodes soaked like a sponge in the electrolyte; this would cause the film to be replaced, as it wore out, or was ruptured. To insure against leakage of the electrolyte the condenser was covered with pitch or wax, filling the spaces between the sides of the box and the condenser proper. The electrodes with intervening gauze were of large area and were rolled upon themselves into a cartridge, one terminal being fastened to the edge of the anode and the other to that of the cathode, to which conducting wires might be attached. Thus the box, sometimes of metal, sometimes not, was insulated from the condenser and the electrolyte had no means of escape. In operation heat is generated by electrolysis and with it gas. As a result the gas forms a path through the pitch or wax, and the electrolyte follows through the passages so made. The connection so established by the electrolyte causes a galvanic action between the metal parts, electrodes and box, if these are of different metals, and a loss of current between the cathode and the box when that is of any metal. One or both of these difficulties had existed in all dry condensers before Georgiev, whenever the box was of metal.

He proceeded upon a new theory. His condenser was, indeed, made up of the same parts as those which preceded, but instead of filling the spaces between the cartridge and the walls of the box with pitch or wax, he left them open, thus allowing any leakage of electrolyte to drain to the bottom and any gas produced to escape. To neutralize corrosion by galvanic action and loss of current, he directly connected the cathode with the box, which he made of the same metal, aluminum. The result was that there could never be any difference in potential between them and no current would leak, the negative terminal being on the box itself. These details are indeed simple when once conceived, but the result was new, and the success immediate and great. The new condensers went into wide use and have largely supplanted the old. Nothing of the sort had appeared before, unless it be Ruben, No. 1,714,191, which was for a dry condenser cell with a space between the top of the box and the top of the cartridge. Nothing appears in the specifications of this patent indicating that this was a part of the invention, and the only basis for claiming anticipation is in the figure. An insulator closely filling the space between the sides of the box and the cartridge, was, however, both shown in the figure and specified. The space at the top did not answer the purposes of Georgiev. If the electrolyte was forced up and into it, it would have the same action as though there had been no insulating cover to the cartridge, and no provision was made to prevent its action after it established a connection between the electrodes and the wall. It is indeed not clear that the space indicated in the figure was intended for more than to disclose the terminals and their connections. In any case the disclosure was plainly insufficient.

It seems to us that, although the combination was not a long step forward, it was enough to support a patent. As we have already intimated, it does not stand merely upon the structural details necessary to carry it out; once conceived these were not serious. Bengough and Stuart, No. 1,771,910, had already disclosed the importance of having all parts, which dipped into the electrolyte, of the same metal, and aluminum at that. This it is true was during the "forming process," but the condenser must be made so that this process shall continue during operation. Moreover, the connection of the cathode to the wall was an obvious enough means of securing equal potential between the two and avoiding current losses. We do not therefore rest upon these, and should agree with the learned judge in thinking that no invention had been made, if that were all. But we think that they were mere incidents of a new, a quite new, idea for such a condenser; that is, not to insulate it at all, but to allow it to be set loosely in the box. This had theretofore been supposed to be objectionable for the reasons we have given. Georgiev thought otherwise and abandoned the uniform...