GB462243A - Improvements in or relating to cathode ray tubes - Google Patents

Abstract

462,243. Cathode-ray tubes. BARASCH, H. P. Sept. 2, 1935, No. 24444. [Class 39 (i)] In cathode-ray tubes with a cathode c having a flat surface at right angles to the axis of an electrode system which includes an apertured electrode g adjacent the cathode c, the cathode or the system is rotatably mounted about an axis parallel to, and spaced from, the axis of the system so that the operative part of the cathode surface can be changed. As shown, an insulating body i carrying the cathode c and containing a heater therefor is rotatably carried in an extension g<3> of the fixed electrode g serving as control electrode. Clamps p<1>, p2 with interposed insulation j<1> . . . j<3> hold the parts g, g<3> and a first anode a together and are mounted on rods m<1>, m<2>. A second anode b is arranged at the top of the anode a. The cathode c is rotated from outside the tube by means of magnetic pieces w<1>, w<2> on arms kl, k2 or by shaking, a single arm with a weight at its end being then provided, or by means of a ground joint in the wall or foot s of the tube. Instead of coating the cathode uniformly with oxide, separate oxide spots may be provided and brought into operation successively. These spots may be of different size or material and may be applied after assembly of the system through the apertures in the electrodes a, g. Small recesses may be provided in the cathode surface to receive the oxide. The pieces w<1>, w<2> may carry getter evaporated by highfrequency heating. In a modification, the circular groove f in the body i engaged by a finger on the part g<3> is replaced by a spiral groove so that rotation of the cathode also adjusts its distance from the electrode g. In other modifications, the part g<3> is insulated from the electrode g and receives the cathode c which contains or is surrounded by an insulated heater.