| 摘要 |
770,333. Cathode-ray storage tubes. HUGHES AIRCRAFT CO. Sept. 28, 1954 [Oct. 23, 1953], No. 28000/54. Class 39(1). A direct-viewing storage tube has a matrix mask provided with apertures corresponding to information characters designed to shape the writing electron beam. The matrix mask 20 is shown in Fig. 2. The writing beam is generated by electron gun 18 and is directed by deflection plates 48, 49 suitably energized from control circuits so that it passes through the desired character on the mask 20. The beam then traverses an electron lens, either magnetic or electrostatic but preferably the latter to avoid image rotation. The electrostatic lens comprises electrodes 59, 60, 61 so designed that the matrix is in focus on the storage screen 12 and the beam cross-overs are at the centres of deflection of further deflecting means 26 which direct the beam to the appropriate part of the storage screen 12. The latter comprises a contrast control grid 110 in a frame 116 and covered with storage dielectric material 114 e.g. talc which has a high specific resistance. A collector grid 112 has adjacent the surface 114 with its mesh wires at an angle to the grid wires 110. Behind the storage grid are the fluorescent screen 122 and a thin transparent conducting layer 120 e.g. of stannous oxide respectively. The flooding gun 16 comprises a cathode 90, intensity grid 91 and annular electrodes 92, 93 and in conjunction with wall anodes 95, 96 it produces a broad beam of electrons over the entire area of storage screen 12. The unity beam shaped successively by the characters of matrix mask 20 lays down on the storage screen 12 a pattern of letters or a symbol. With the control grid 110 at an appropriate potential, electrons are liberated by the high speed writing beam, imparting a positive potential to the impacted surface and the flood beam liberates a further excess of electrons to increase the charge contrast. To view the image, the contrast control grid is made sufficiently negative to cause the flood electrons to be repelled except at the apertures where the charge is positive, which apertures they penetrate to be accelerated onto the viewing screen. To erase the characters on the screen the potential of the grid 112 is momentarily lowered to less than the critical potential of the storage material, clearing the storage surface to return to the potential of the flood gun cathode. Specification 758,677 is referred to.
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