Motography (Apr-Dec 1911)

182 MOT O G R A P H Y Vol. VI, No. 4. Recent Patents in Motography By David S. Hulfisk It will be the purpose of this department to list all United States patents, as they are issued, which pertain to any form of amusement business, giving such data in each case as will enable the reader to judge whether he wishes to see the complete drawings and specifications of the patent. When patents of special interest to Motography readers are encountered, the descriptive matter herein will be amplified accordingly. A complete copy of drawings, specifications and claims of any patent listed will be furnished from this office upon receipt of ten cents. UNITED STATES Patent No. 993,889. Vapor different circuits of the rectifier, the lowest curve rectifier system. Charles P. Steinmetz, Sche showing the ultimate current delivered, approximating nectady, New York, N. Y., assignor to General a direct current from a generator of but few commuElectric Company of same place. tator segments. Not only in the arc lamp for the projecting Ian The system shown comprises constant current tern, but in the artificial lighting of the motion pic transformer i, having a fixed primary winding 2, supture studio, the direct current is found more serviceable than alternating current. Alternating current is found more convenient for power distribution by the electric service corporations, hence it happens frequently that the user of current for motion picture purposes needs direct current and can buy conveniently only the less serviceable alternating current. The mercury arc rectifier is a means for changing an alternating current into a current having all of its pressure values exerted in the same direction. With the rectifier of the ordinary type, the resulting current is far from the smooth current of the directcurrent dynamo. It is to produce with the rectifier a current approximating more nearly the direct-currentdynamo product that Mr. Steinmetz takes as his desideratum in the present patent. A double rectifier is used, and the supply is split into two currents, alternating in nature but out of phase. When these two currents are separately rectified and their resultants are superposed, a current is 993,899. produced which is smoother than that resulting from the rectification of a single alternating current. The illustration accompanying this review combines both Fig. 1 and Fig. 2 of the patent, the former showing the circuits of the double rectifier, and the latter showing graphically the current values of the 994,042. plied with energy at constant potential, and also having a floating secondary winding j, from which energy is supplied to other parts of the system through the terminals 4 and 5 and the central tap 6. The vapor rectifier 7, included in the system, is of ordinary type, having anodes 8 and 9 and a mercury cathode 10. The rectifier may be excited by means of auxiliary anodes 11 and 12 receiving energy from an exciting transformer 13. A series consumption circuit 14 is connected between the mercury cathode 10 and the central tap 6 of the transformer secondary 3, and may include lamps or other devices adapted to operate on substantially constant current. Interposed between the mercury rectifier 7 and the transformer leads 4 and 5 are the reactance devices 15, 16 and 17. Reactances 75 and 16 are connected in series with their respective leads 4 and 5, but reactance il has a double winding and exerts an influence on both the anode circuits. One leg of reactance il is wound with a coil 18 traversed by the pulsating current delivered to anode 8, while the opposite leg is wound with a coil ig traversed by the pulsations delivered to anode p. The two coils 18 and 19 are so disposed on the core that they magnetize in the same direction, that is, in a direction to increase the total flux throughout the entire magnetic circuit of the reactance. To prevent saturation of the core, I prefer to make it in two parts separated by air gaps as indicated in the drawing. Owing to the shape of the core, a certain amount of magnetic leakage takes place around each of the wind