Method and device for measuring convergence in a color picture tube

摘要

A method and a device are specified for measuring the position of an electron beam in a multi-beam colour cathode ray tube with respect to the field of view of an image converter whose electron beam produces a bright-up pattern (brightness pattern) on the screen of the tube, the screen having fluorescent strips for different colours, and a shadow mask being provided in front of it which has elongated slots in the direction of the fluorescent strips. On the basis of known methods, in the case of which an electron distribution pattern is produced and is converted into a charge pattern, with the aid of an image converter, for subsequent evaluation, the invention specifies that the electron distribution pattern which is produced has dimensions of a few millimetres and at least one edge of it is inclined with respect to the longitudinal direction of the mask slots, and that the bright-up pattern is imaged on the image converter such that it completely fits the image converter's field of view. The inclined pattern edges ensure that sudden changes in measured values (measurements) are avoided. IMAGE