Scovill Mfg. Co. v. Balistocky

48 F.2d 875, 9 U.S.P.Q. (BNA) 172, 1931 U.S. Dist. LEXIS 1264
District Court, E.D. Pennsylvania·Decided April 8, 1931·No. No. 4961·Published·Cited by 5 cases

Opinion

THOMPSON, District Judge.

This is a suit in equity brought by the Seovill Manufacturing Company against the defendants, trading as Post Radio Company, for an injunction and for damages for alleged infringement of patent No. 1,258,423, issued to Fritz Lowenstein on March 5,1918, upon an application filed August 10, 1916, which is a division of an earlier application filed June 28, 1910. The defenses are non-infringement and invalidity because of lack of invention and also by reason of anticipation.

The patent in suit, whieh is owned by the plaintiff under mesne assignments, relates to variable electrical apparatus and more particularly to condensers adapted for use in wireless or radio work. The patent was in suit in the district of Connecticut. Judge Thomas' sustained the validity of claims 1, 2, 3, and 4. See Scovill Manufacturing Co. v. Satler (D. C.) 21 F.(2d) 630.

No clearer description of variable condensers and of the condenser of the patent could be given by the writer than the following statement by Judge Thomas, including his observations on the meaning of claims 1, 2, 3, and 4:

“The invention of the patent in suit relates to variable condensers adapted for use in radio or wireless work. Broadly defined, a condenser comprises a plurality of surfaces insulated from each other, which afford an area on whieh an electrical charge is stored. The invention of the patent in suit is more particularly directed to that type of electricál condenser whieh comprises a set of stationary spaced metal plates and a series of movable spaced metal plates; the latter being adapted to be interspersed to a greater or less degree between the stationary plates to effect changes in the capacity of the condenser.
“In the most commonly known variable electrical condensers of the type mentioned, both sets of plates are semicircular; the stationary plates being separated from each other a uniform distance, while the movable plates, which are mounted on a rotatable shaft, are also separated a uniform distance from each other in absolute parallelism. The layers of air between juxtaposed surfaces of the plates constitute the. insulating medium or dielectric of the condenser. The dielectric prevents an electrical charge whieh is collected on the juxtaposed surfaces from jumping across and thus short-circuiting and rendering the condenser useless. The ability of a eondenser to store electrical charges is known as capacity, whieh is measured in micro-microfarads, which in turn is one-millionth of a millionth of a farad; the farad [876] being a very large unit. The capacity of a condenser depends directly on its .area, so that area and capacity are equivalents in speaking of condensers.
“In the condenser just described, the ■change in area of the movable plates active between the stationary plates is always the same for equal angular movements of the shaft, with the result that for a given angular movement of the shaft there will be the same increase or decrease of capacity throughout the range of movement of the movable plates, no matter where that movement may be made. The movable plates turn through -an angle of 180°. In other words, this variable condenser is so designed that equal angular movements or displacements of the movable plates within the working range of the instrument produce unequal percentage variations in capacity.
“The main object of the invention described in the patent in suit is to so design the instrument, for a purpose hereinafter described, that a given angular displacement of the movable plates produces substantially the same percentage change in capacity at any point within the range of the instrument. The condenser described in the patent in suit includes, preferably, a set of semicircular stationary condenser plates 14, supported in parallel relation by rods 15, which depend from a cover plate and are clamped thereto by nuts 16 and 17. The stationary condenser plates are uniformly spaced apart by collars 18. The parallel movable condenser plates 21a are secured to a central vertical shaft 22, which is supported at its lower end on a pivot 23 and is held at its upper and in a bearing 24 in the cover plate. Spacing collars 25 are provided to maintain the plates 21a the proper distance apart, and they are securely clamped in position between nuts 26 and 27. The relative positions of the fixed or stationary plates and the movable plates are such that, when the central shaft is ■turned, the movable plates enter the spaces between the fixed plates. The movable plates, with the exception of five at the top of the set which are of equal size and a little more than semicircular, are cut off at angles which are progressively greater from the top downward. As a result, the edges of the movable set of plates are arranged in step-like fashion, so that the movable plates enter successively between the stationary plates as the shaft is turned. The proportioning of the plates and their arrangement is such that the capacity of the condenser is variable, following substantially the law of geometrical progression or in accordance with a logarithmic law fully set forth in the specification of the patent in suit. It is due to such proportioning and arrangement of the plates that a given angular displacement of the movable plates produces substantially the same percentage changes in capacity at any point within the range of the instrument and that the change in capacity is much more gradual than in a condenser where both sets of plates are semicircular.

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Scovill Mfg. Co. v. Balistocky, 48 F.2d 875, 9 U.S.P.Q. (BNA) 172, 1931 U.S. Dist. LEXIS 1264 (E.D. Pa. 1931).

48 F.2d 875 (Scovill Mfg. Co. v. Balistocky) — published by Counsel Stack Legal Research, free access to 12M+ legal documents.

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