Патент USA US2129037код для вставки
Sept. 6, 1938. K. S'CHLESINGER 2,129,037 DETECTOR Original Filed Nov. 7, 1934 Jake/#0,.” . MW Patented Sept. 6, 1938 2,129,037 UNITED STATES PATENT QFFECE 2,129,037 DETECTOR . >Kurt Schlesinger, Berlin, Germany, assignor to Radioaktiengesellschaft D. S. Loewe, Berlin Steglitz, Germany Original application November 7, 1934, Serial No. 751,927. Divided and this application June 5, 1936, Serial No. 83,704. In Germany Novem ber 10, 1933 3 Claims. (Cl. 250—27) In the recti?cation of carrier waves preferably modulated with a frequency band of large width, good insulating coating, on the surface of which, however, there is provided a conductive layer 24, e. g., as occurring in television, there are» em~ which is common to both grids and may be con nected with a terminal 22. Valves of this char acter have for television purposes, in accordance ployed with advantage grid detector arrange 5 ments, preferably of the push-pull type, as in these recti?ers the carrier wave is removed from the output circuit by compensation, a disturbing grain in the image thus being avoided. In this connection it is necessary, generally speaking, 10 assuming it is desired to avoid an expensive re versing tube, to employ transformers, as already shown by the applicant in his earlier application No. 747,011 and Patent 2,068,769. With trans formers of this nature, however, there is en 15 countered the characteristic difliculty that, gen erally speaking, the secondary potential is in no way symmetrically positive and negative against earth, but always reveals a one-sidedly directed additional potential. 20 The stated methods are of signi?cance only in connection with- freely oscillating coils, the centres of which cannot be earthed in direct fashion. This connection alrises consequently upon use of the push-pull detector without grid 25 condensers as in the patent application No. 747,011. The present invention is an improvement of grid-current detector arrangements preferably of those operated in push-pull connection and is 30 a division of Patent 2,072,315. By the arrange ment according to the present invention it is possible by special construction of therecti?er valve to have in fact a sufficient blocking of the modulation potential against short-circuiting by 35 the high frequency input coil of the detector valve and at the same time good e?icie‘ncy. The present invention is relative to a particlular em bodiment of a grid current detector arrangement, more particularly for television purposes, where 40 in a detector valve is employed having control electrodes comprising at least one grid, which is insulated completely or incompletely from the inner electronic discharge space and is furnished with a conductive layer arranged on the insulat 45 ing coating thereof. In a preferred form of the present invention a double grid detector‘ valve is employed in push-pull fashion in connection with transformer input coupling. In a preferred form of the present invention 50 set forth in the accompanying drawing there is ‘employed as detector a valve l9 having an insu lated grid, or preferably two insulated grids 20, 2|, which are similar and have the same ampli? cation factor and arranged to co-operate with the 65 common cathode 23, and are furnished with a with the invention, the following advantages. A potential produced in the push-pull. trans former coil 4 may be applied directly and un weakened to the grids 20, 2| without grid con densers, which on account of their requisite small 10 size would mean a considerable loss in sensitive ness. Since these grids are insulated against the interior of the Valve, the middle of the trans former 4 may be connected directly with‘ earth. An incoming particular positive half-wave causes 16 the outer coating 24 common to both grids to be charged negatively. This charge is leaked away by a resistance 25, which may either be provided outside of the valve, or alternatively the leak may be provided inside the valve by making the insu 20 lating layer slightly conductive. As will be ap parent, it is possible, particularly in. the latter case, to reduce considerably the capacity of the arrangement, and in consequence to employ a comparatively larger grid leak resistance 25 than 25 in the circuits shown in Patent 2,068,768, so that the sensitiveness of the arrangement may be fur ther increased as compared with the previous ar rangement with the same lack of inertia. Owing to the possibility of earthing the transformer coil 30 4 in direct fashion, the danger of lack of sym metry is practically obviated, so that proper com pensation of the carrier wave is possible. I claim: 1. A push-pull grid-current detector arrange ment, more particularly for television purposes comprising a detector valve having two separate grids connected in push-pull, anda secondary of an input transformer, said two grids being ar-‘ ranged with the same ampli?cation factor op posite a common cathode which is directly earthed and being insulated from the inner electronic dis charge space by an insulating coating and fur nished with a conductive coating arranged on the insulating coating, and common to both grids, 45 the ends of said secondary being earthed in its midpoint and connected directly to the grids, said conductive coating being connected to the oath ode of said valve. 2. A push-pull grid-current detector arrange 50 ment, more particularly for television purposes comprising a detector valve having two separate grids connected in push-pull, and a secondary of an input transformer, said two grids being ar ranged with the same ampli?cation factor oppo 55 2 2,129,037 site a common cathode which is directly earthed and being insulated from the inner electronic dis charge space by an insulating coating and fur nished with a conductive coating arranged on the insulating coating thereof, and common to both grids, the endsofsaidsecondaryearthedinits mid point connected directly to the grids, said conduc tive coating being connected to the cathode via a special leakage resistance, said insulating coating 10 consisting of a complete insulating material. 3. A push-pull grid-current detector arrange ment, more particularly for television purposes comprising a detector valve having two separate grids connected in push-pull, and a secondary of an input transformer, said two grids being ar ranged With the same ampli?cation factor op posite a common cathode which is directly earthed and being insulated from the inner elec tronic discharge space by an insulating coating and furnished with a conductive coating arranged on the insulating coating thereof, and common to both grids, the ends of said secondary earthed in its midpoint connected directly to the grids, said conductive coating being directly connected to the cathode of said valve, said insulating coating consisting of a semi-conductive material. KURT SCHLESINGER.