GB542488A - Improvements in or relating to electron discharge devices - Google Patents

Abstract

542,488. Cathode-ray tubes. McGEE, J. D., MILLER, H., and FREEMAN, G. S. P. May 2, 1940, No. 7892. [Class 39 (i)] In a cathode-ray tube wherein the ray is subjected to a uniform longitudinal magnetic field as described in Specification 530,409, the ray is modulated by subjecting it to the action of an electrostatic field between deflecting electrodes, so that the deflected ray emerges substantially parallel to its original direction and is then interrupted by an electrode through an aperture in which it passes by an extent depending on the amount of deflection. Fig. 1 shows an arrangement in which the plate 10 has a wedge-shaped aperture 9 as shown in Fig. 2 and the ray is directed towards the apex of the wedge by the deflection produced by plates 7, 8. 5, 6 are plates for producing scanning deflection. The electrode 4, which acts as a stop for defining the ray, and the electrode 10 are preferably arranged as described in Specification 542,496. After the ray has passed through the aperture 19 it may be restored to its original line by a second pair of plates carrying potentials equal and opposite to those of the plates 7, 8. The ray may be centred between the electrodes 5, 6 by the means described in Specification 542,497. Fig. 7 shows an arrangement in which the ray is caused to be compacted to a greater or less extent into the plane of the lower edges of the plates 14 and more or less interrupted accordingly by an electrode with an aperture 16 through which the ray passages. Plates 17 diminish the fringing effect at the edges of the plates 14.