Method of determining a display parameter of a raster scan picture display tube, and method of treating such a tube for improving picture display

摘要

A method of determining display parameters for a picture tube. An image pattern having a modulation frequency is displayed on the display screen. The fundamental wave of the image pattern is determined, information about the sharpness of the focus can be derived from the modulation depth of the fundamental wave, the position of the electron beam can be determined from the phase of the fundamental wave.