Abstract: A cathode ray tube may utilize a focus mask color-selection structure. The focus mask structure is susceptible to localized, transient short circuit events, or breakdown events. These events may be caused by conductive particulates that become free within the cathode ray tube and provide a short circuit between first and second layers of the focus mask. The breakdown events are undesirable because they may result in cross-strand currents causing mask strand magnetization that can interfere with a video image on the screen of the cathode ray tube. A rapid degaussing operation is initiated during the next subsequent vertical blanking period following detection of the breakdown event.

Abstract: A color tube of the automatic convergence kind comprises three coplanar electron beams, with magnetic coma defect correction elements situated to the rear of the deflector unit. For the case where these defects are of small size, of the order of 1 mm or less in each direction, and of opposite sense in the horizontal and vertical directions, the correcting elements are formed by four plates of rectangular shape and whose plane is perpendicular to the axis of the tube. The plates are situated above and below each of the lateral beams and one dimension of each of the plates affects the amplitude of the correction in one direction, and the other dimension affects the coma correction in the other direction.

Abstract: The present invention relates to a process and a device for adjusting a deflection unit without utilizing a test tube whereby a measuring head is employed that samples the field along the length of the axis of the deflection unit in at least two zones, and the signals issuing from the measuring head represent the fields generated by the line and raster windings. These signals are connected to a computer that simulates the mechanical adjusting operations such that the error signal supplied to a servo-device may control the displacement motors of the raster with respect to the center line of the deflection unit.