Condenser Development Corp. v. Davega-City Radio

• Decision Date: 18 December 1939
• Docket Number: No. 67.,67.
• Citation: 108 F.2d 174
• Parties: CONDENSER DEVELOPMENT CORP. v. DAVEGA-CITY RADIO, Inc.
• Court: U.S. Court of Appeals — Second Circuit

108 F.2d 174 (1939)

CONDENSER DEVELOPMENT CORP. v. DAVEGA-CITY RADIO, Inc.

No. 67.

Circuit Court of Appeals, Second Circuit.

December 18, 1939.

James & Franklin, of New York City (Maxwell James, of New York City, of counsel), for plaintiff-appellee.

Ward, Crosby & Neal, of New York City (Charles W. Owen, of Toledo, Ohio, and Joshua Ward, of New York City, of counsel), for defendant-appellant.

Before SWAN, CHASE, and CLARK, Circuit Judges.

CHASE, Circuit Judge.

The plaintiff, the owner of Patent No. 1,800,719 granted April 14, 1931 to Stanley S. Cramer for an electrical condenser on his application filed January 15, 1929, is a company holding patents under which it grants licenses. The nominal defendant is a distributor of radio receiving sets in the Southern District of New York who has there sold such sets which included certain variable condensers which the plaintiff contends infringed claims 4, 10, 11, 17 and 18 of the above patent. These condensers were made by The American Steel Package Company which is defending the suit and is to be bound by the final decree. All of the claims were held valid and infringed and the defendant has appealed.

The patent in suit relates to a variable condenser of the kind commonly used to tune a radio receiving set to pick up the broadcasts from various sending stations as desired within the range of the set. It is usually of the multiple type known as the gang condenser and its maximum efficiency is attained only when each unit of the condenser may be adjusted to the maximum point of the resonance curve by turning a shaft which carries all the rotors and holding the shaft in the attained position throughout the reception period. Many variable gang condensers that could be so tuned and would effectively stay tuned were on the market before Cramer applied for the patent in suit. He disclosed nothing new in respect to the electrical features of a variable gang condenser. What he did was to use what is claimed to have been a new kind of ball bearing for the rotor shaft bearings and the combination of such bearings with the old variable gang condenser is the combination covered by all the claims in suit.

In order to understand the problem which Cramer undertook to solve, it is necessary to have in mind the general nature of a variable condenser. A variable gang condenser is only what is in effect two or more variable condensers which may be tuned at the same time but which are nevertheless separate units from the standpoint of their electrical functions in the receiving set. This feature is brought about by mounting the rotors of each condenser on the same shaft; placing each set of stator plates in position to co-operate with the rotor plates for that set; and shielding each unit made up of a set of rotors and stators from each other such set to make each sufficiently immune from disturbance by electrical currents outside what may be called its own compartment. The rotor shaft and the stator plates are all carried by the same frame and, as these are air condensers whose capacity is comparatively small, it is essential to satisfactory operation that the fixed distance between the rotor plates and the stator plates be kept constant throughout the turning range of the rotors in order that the tuning characteristics of each condenser unit may be maintained. It was found difficult to make a frame which would provide such nearly perfect alignment for the front and rear ends of the rotor shaft that the shaft would not bind when placed in position and set up stresses in the frame which brought about a change in the tuning characteristics of the condenser as the rotor shaft turned the rotor plates in the tuning operation. This binding also caused excessive wear and did not permit the shaft to turn with even smoothness. When sufficient care was taken to get the required alignment, the cost of construction was comparatively high. Attempts to overcome the trouble had been made and substantial success had been attained by the use of a cone type of bearing which did allow the shaft to adjust itself somewhat to the position it was required to assume when placed in a frame in which the holes made for the bearings were not properly aligned.

The step which Cramer took to...