Abstract: A cathode ray tube (CRT) having a glass envelope is disclosed. The glass envelope is formed of a rectangular faceplate panel and a tubular neck connected thereto by a funnel. An electron gun is positioned in the neck for directing electron beams toward the faceplate panel. A yoke is positioned in the neighborhood of the funnel-to-neck junction. The yoke has windings configured to apply a horizontal deflection yoke field and a vertical deflection yoke field to the beams. At least one magnetic field sensor is located near the glass envelope for sensing an ambient magnetic field environment of the CRT. A controller receives a signal from the magnetic field sensor. Register correction coils are mounted in the vicinity of the neck and are dynamically controlled by the controller to shift the beams.

Abstract: The CRT (10) according to the invention has an envelop (11) including a panel (12) attached to a funnel (15), the funnel having a neck (14) and an electron gun (26) for generating at least one electron beam (28) contained in the neck. A mask (25) is contained in the envelop near the panel. A region of the mask has columns (30) of apertures (31) of predetermined heights and predetermined pitches. The at least one electron beam has a spot size range and spot shape selected such that the moiré transformation function for the CRT in the region is less than about 0.02, wherein the moiré transformation function is a quotient having a numerator being the difference between a maximum value and a minimum value of mask transmission and a denominator being the sum of the maximum and the minimum values.

Abstract: A first magnetic field producing member has its poles oriented for producing an initial predetermined movement of the two outside ones of three in-line beams of a cathode ray tube. Second and third field producing members are adjustable for producing variable strength and direction of magnetic fields for moving the two outside beams in opposite and the same directions, respectively, for converging the three beams.