The design and performance of picture tubes having 8????????-in screens, 90 deg deflection angle, and using permanent-magnet quadrupole scan magnifying lenses is described. These tubes require only a thirtieth or less of the line scanning power of a conventional tube having the same final anode voltage and deflection angle. Field scanning power is also slightly reduced. Descriptions of both magnetic and electrostatic focusing systems are given. The magnetically focused tube suffers from the disadvantages that it requires an extremely stable e.h.t. supply and a large number of focusing adjustments. The electrostatically focused tube requires no more stabilization of e.h.t. than is usually provided for conventional tubes, and reduces the number of focusing adjustments considerably. However, the increased length of the tube (40% greater than conventional tubes) and increased complexity of manufacture and adjustment compared with conventional tubes, coupled with the need for a separate e.h.t. and video h.t. supply generator, has led the author to the conclusion that this technique has little to offer at the present stage of picture tube development.
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