Appeal from the District Court of the United States for the Northern District of Illinois, Eastern Division; Charles E. Woodward, Judge.
Before ALSCHULER, SPARKS, and FITZHENRY, Circuit Judges.
Appellee brought this action to recover for infringement of claim 7 of Chandeysson United States patent No. 1,564,939. Appellants pleaded invalidity and non-infringement, and by counter-claim, the appellant, The Safety Car Heating and Lighting Company, charged appellee with infringement of certain claims of United States prior art patents owned by it, as follows: Moskowitz, No. 1,291,597, claims 11, 19, 20, 21, and 23; Bijur No. 1,260,995, claims 17, 18, 19, 20, and 33; and Armstrong No. 1,163,306, claims 25 to 32 inclusive. To this counter-claim appellee pleaded invalidity and non-infringement, and the cause was referred to a special master. Upon the facts found in the master's report he concluded that claim 7 of the Chandeysson patent was valid but not infringed; that the claims of the Moskowitz patent and those of the Armstrong patent were valid and infringed by Chandeysson; that claims 17, 19, 20, and 33 of the Bijur patent were invalid in view of Moskowitz; and that claim 18 of Bijur was valid but not infringed by Chandeysson. He further concluded that appellee was entitled to no relief and that its bill should be dismissed, and that appellant was entitled to the relief prayed for in its counter-claim.
The District Court decreed that claim 7 of the Chandeysson patent was valid and infringed and that it did not infringe any of the said claims of Moskowitz, Bijur or Armstrong, and that appellee was entitled to the relief prayed for in its bill. The counter-claim was accordingly dismissed, and from that decree this appeal is prosecuted.
The patents in suit relate to regulators which comprise carbon piles and are particularly adapted, but not limited, to use in car lighting systems to control the voltage to which the lamps are to be subjected. Generally the patents show and describe regulators comprising carbon piles that may be connected in series with lamps, means being provided whereby the electrical resistance of the carbon piles is varied in response to variations in voltage in the lamp circuits. The means comprise in each instance an electric magnet or solenoid which, acting in response to changes of voltage across its winding, either releases the pressure to which the carbon piles are subjected or subjects them to such pressure. The carbon piles comprise a plurality of carbon disks in contact with each other. When compressed their electrical resistance is lowered, and when released from pressure they elongate and increase in electrical resistance.
The Chandeysson patent discloses a regulator which in one form comprises such a carbon pile 4, positioned within an insulating tube 5. Metallic disks 3 in the ends of the tube are insulated from the pile by insulating disks 6, as shown in Fig. 8. A thrust member, or a fixed supporting member, equipped with a conical projection, is socketed in a corresponding recess formation in one of the metallic disks, as at 13, Fig. 9. A similar  conical projection 24 is socketed in a corresponding recess formation in the other metallic disk, the latter conical projection being pivotally connected at 21 with a lever 20, which at its right end carries the core or plunger 19 of the solenoid 17. The lever 20 also carries a rigid riser 25 through which an adjustable screw 13 is threaded. 26 designates an optional stop in pin which prevents the lever 20 from descending by force of gravity or other means below that point. It is to be noted that the member extending from 21 to 24 is rigidly and firmly attached to frame 15, and the carbon pile with its insulating tube is held in suspension by the conical projections at each end. When the core of the solenoid 19, which is a part of the lever 20, is raised and lowered, it necessarily raises or lowers the right end of the carbon pile and its container, and this action is permitted by the pivotal action at 24 as well as the pivotal action at 21. When the solenoid is not energized, the right end of the carbon pile is held at its lowest point by gravity, which is an equivalent of the spring used in appellants' device, and the carbon pile then reaches its highest point of compression and conductivity. When the solenoid 17 is energized it draws the core 19 and the lever 20 and the right end of the carbon pile upwardly as shown by the dotted lines in Fig. 9. This of necessity releases the pressure on the carbon pile which results in a corresponding decrease in its conductivity.
Chandeysson in his application said:
"While compressible resistances of the general type of carbon piles have long been employed, such carbon piles have commonly been objectionable both because of the variations in resistance due to friction between the disks of the pile and to friction between the disks and their inclosing tube, and because of the irregular variations in resistance due to a relative tilting or canting of the disks constituting the pile. For example, such carbon piles have commonly been mounted on a rigid support and the variation in pressure has commonly been exerted in such a way as to tend to rotate, tile or otherwise shift the relative position of the carbon disks comprising the pile, thereby introducing both a waste of energy in the mechanism employed for varying the compression and an uncertainty as to the effective resistance secured with any particular position of this mechanism. Both this waste of energy and the uncertainty as to the resulting resistance have been further increased by the friction of the disks against the tube inclosing the same and by the friction in the mechanism employed for varying the compression.
"Moreover, the mechanisms commonly employed for varying the compression of a compressible resistance have disregarded the fact that the change in resistance does not vary uniformly with pressure but varies according to a hyperbolic function of the pressure. Consequently, where the movement of the actuating member is substantially in proportion to the actuating effort, as in the case of a solenoid moved by the flow of current through the solenoid, the resulting change in pressure did not respond with any uniformity to the changes in the actuating effort. * * *
"My present invention aims to overcome all of the above named objections to rheostats of the compressible resistance type and aims to do so by employing an exceedingly simple and durable arrangement of parts. For this purpose, my invention aims to provide a construction in which the carbon pile is movable as a unit and is not supported by the tube or other guide which maintains the carbon disks in alinement, and one in which the pressure is applied to the carbon pile axially of the latter so as to prevent any relative movement of the constituent disks, thereby eliminating the heretofore objectionable friction and uncertainty of the resulting resistance."
Claim 7 of the Chandeysson, upon which appellee solely relied, is as follows:
"7. In combination, a compressible resistance, thrust means pivotally connected to the resistance at one end, and a lever pivotally connected to the other end of the resistance and co-operating with the thrust means in affording the entire support for the resistance."
This claim covers what was referred to in the record by appellee's expert as the "floating pile construction" although that name is not given to it in either the claim or the specifications. It means that when the regulator is in operation the carbon disks are suspended and supported solely by the thrust means and ...