| 摘要 |
471,399. Detecting circuits ; electronmultipliers. FARNSWORTH TELEVISION, Inc. March 2, 1936, No. 28071. Convention date, March 12, 1935. Divided out of 471,199. [Classes 39 (i) and 40 (v)] Radio signals are detected by applying an alternating voltage derived therefrom between opposed secondary electron - emitting cathodes 60, 61, the signal or an intermediate frequency appearing in the circuit of an anode 62 between the cathodes. The time of flight of electrons between the cathodes may be adjusted to correspond to the signal frequency. The cathodes are connected across a tuned circuit 64 earthed at its centre 65 and energized directly or through a radiofrequency amplifier from an aerial 67. The anode 62 may be connected to a steady positive potential source or its circuit may include a tuned circuit 70 fed from an exciting oscillator to interrupt periodically the multiplier action and to feed an intermediate frequency amplifier operating at the interrupting frequency. The cathodes 60, 61 are sensitized with caesium and may be plane, with an applied magnetic field 71. In modifications, the cathodes form opposed semi-cylinders, the magnetic field is omitted, and the anode is a central rod connected to and surrounded by a grid to increase its collection of electrons or is a grid surrounding a light-emitting filament energizing the photo-electric surfaces of the cathodes. The multiplier may be self-oscillating at a frequency determined by an inductance in its anode circuit and may then operate as a regenerative or super-regenerative detector. The self-oscillation periodically interrupting the multiplication may be on a negativeresistance part of the multiplier characteristic or at a difference frequency between the signal and the electron oscillations or between the signal and an exciting radio-frequency. The Specification as open to inspection under Sect. 91 comprises also subject-matter described in Specification 471,199. This does not appear in the Specification as accepted. |
