GB684580A - Improvements in electron beam tubes - Google Patents

Abstract

684,580. Electron beam apparatus. PHILIPS ELECTRICAL INDUSTRIES, Ltd. April 6, 1950 [April 9, 1949], No. 8762/50. Class 39(i) An electron beam tube, suitable for use in a circuit arrangement in which the beam is held in determined positions by current distribution between at least two collecting electrodes and in which the variation of current to one collecting electrode with deflection voltage has a number of maxima and minima, is characterised in that one collecting electrode 15 has a number of apertures provided side by side in the direction of deflection of the beam, the width of the apertures being less than the width of the beam. The apertures are preferably slit shaped and this width is preferably progressively decreased from the largest 9, to the smallest 3; since it may be impracticable to make apertures 1 and 2 narrower than aperture 3 this length may be made smaller. At each end of the row there may be wide apertures 0 and 10, and behind the aperture 10 there may be a separate collecting electrode for use with a "fly-back" circuit. Additional apertures 19, 20 may be provided above and below the row and the larger aperture 20 may be in fact covered with metal gauze 21. A suppressor grid 18 may be provided and its wires are preferably aligned with the upper and lower sides of the apertures 19, 20. With this arrangement the anode current 1 may be made to increase progressively with the deflection, as shown in Fig. 2, there being a large maximum at each end; the peak at the left is used for the fly-back and may be made narrower by providing a narrow collecting fly-back electrode behind the aperture 10 or by arranging the fly-back electrode partly behind the electrode 15. Specification 684,552, [Group XL(c)], is referred to.