| 摘要 |
707,125. Electrode materials and processing. RADIO CORPORATION OF AMERICA. May 16, 1952 [June 1, 1951; June 1, 1951], No. 12487/52. Class 39(1) [Also in Group XXXVI] The light-sensitive element for an electric discharge tube comprises a layer of red antimony trisulphide evaporated on to a supporting member. A transparent signal layer underlies the photoconductive layer. Apparatus for preparing the photo conductive target comprises a glass bell jar 13 on a flat base 15 with an evacuating pump assembly 21, 60. The red antimony tri-sulphide is contained in a crucible 35 formed by twisting tungsten wire into a conical spiral and coating it with aluminium oxide. Insulating sleeves enclose the leads and a shield 39 directs the material on to the end wall 31 of the tube 29 or a separate transparent member thereon. An auxiliary heating coil 41 is located outside and close to the end face 31, which as a preliminary step has received an internal layer 43 of transparent conducting material, such as a tin compound, followed by baking. This layer 43 is connected to a conducting ring 45 passing through the tube wall. The heater 41 preheats the end wall for cleaning purposes and maintains the processing temperature measured by a thermocouple 32 held to the tube wall by a clamping ring 34. The heater is switched off during evaporation which continues for about half an hour, the thickness of the coating being determined by evaporation time, by counting interference fringes or by photometric comparison with a standard target thickness. Further processing of the tube includes mounting screen electrodes and an electron gun therein with consequential degassing and baking. The temperature should not exceed 225‹C to prevent formation of the undesirable black form of antimony trisulphide. Air-blast cooling may be used. |
