Abstract: A photoconductive element having a photoconductive layer containing a polycarbonate binder based on di-(monohydroxyaryl) alkane, wherein the polycarbonate contains a branching agent selected from the group consisting of 1,2,4-benzene tricarboxylic acid, 1,3,5-benzene tricarboxylic acid, 1,2,4-benzene tricarboxylic acid chloride and 1,3,5-benzene tricarboxylic acid chloride.

Abstract: The initial emission and the lifetime of oxide cathodes are considerably improved by adding small quantities of rare earth metals (10-500 ppm).

Abstract: A cathode having a short heating time and a long lifetime for an electric discharge tube is provided. The cathode comprises a metal (particularly nickel) support base coated with a layer of potentially electron-emissive material, which support base has a thickness ranging between 20 and 150 .mu.m, while the metal crystallites have a size which does not permit of any further crystallite growth or recrystallization. Particularly, the crystallites of the support base have a size which corresponds to the thickness of the support base. The cathode is obtained by a method in which the recrystallization thermal treatment is effective to prevent additions in the metal of the support base from forming oxides to a depth which is further than 1 micrometer from the surface.

Abstract: The zero-hour emission of oxide cathodes comprising for example BaO.SrO as an emissive material is improved by adding europium oxide or ytterbium oxide. Moreover, addition of lutetium oxide improves the lifetime properties.

Abstract: The emission properties of oxide cathodes, in which yttrium oxide, scandium oxide or a rare earth oxide is added to the electron-emissive material, are improved by using fine-grained yttrium, scandium or rare earth oxide.

Abstract: The lifetime of oxide cathodes comprising, for example BaO and SrO as an emissive material, is improved by adding hafnium oxide or zirconium oxide.

Abstract: Cathode for an electric discharge tube having a short warm-up time and a long lifetime. The cathode comprises a metal (particularly nickel) support base coated with a layer of potentially electron-emissive material, which support base has a thickness ranging between 20 and 150 .mu.m, and metal crystallites having a size which does not permit of any further crystallite growth or recrystallization. Preferably, the crystallites of the support base have a size which corresponds to the thickness of the support base.

Abstract: A camera tube target (9) which is to be scanned on one side by an electron beam (20), comprises a selenium-containing vitreous layer (21) also containing tellurium and arsenic. In order to improve various target characteristics and properties in accordance with the invention, the concentration of at least one of the elements tellurium and arsenic in a first sub-layer (25) of the selenium-containing layer (21), on the side to be scanned, increases toward the side to be scanned to a value at which the sum of the concentrations of tellurium and arsenic is at most 30 at. %. The arsenic concentration everywhere in the layer (21) exceeds 1.5 at. %. In a second sub-layer (26) adjoining the first sub-layer (25) the concentration of at least one of the elements arsenic and tellurium is smaller than its concentration an adjoining third sub-layer (27). A fourth sub-layer (28) may also be present between the third sub-layer (27) and the signal electrode (22).

Abstract: A camera tube having an electron source and a target to be scanned on one side by an electron beam emanating from said source. Radiation forming the image to be detected is incident on the other side of the target. The target comprises a signal electrode and a selenium-containing vitreous layer containing arsenic. The arsenic concentration in the selenium-containing layer increases continuously from the radiation-receiving side of the layer to the side which is scanned by the electron beam. The signal electrode is on the radiation-receiving side of the layer and thus on the radiation-receiving side of the target.

Abstract: A camera tube having an electron source and a target to be scanned on one side by an electron beam emanating from the source. The target comprises a signal electrode and a selenium-containing vitreous layer containing tellurium, in a concentration which varies in the direction of the thickness of the selenium-containing layer, and arsenic. The selenium-containing layer is on the side of the target to be scanned by the electron beam, the signal electrode is on the side of the target to receive radiation. The tellurium concentration in the selenium-containing layer increases from the radiation-receiving side of the layer to the side which is scanned by the electron beam in such manner that over a distance of at most 0.3 microns from the radiation-receiving side, the concentration reaches a value of at least 41/2 atomic % and the arsenic concentration uniformly exceeds 11/2 atomic %.