SU1281184A3 - Three-colour picture cathode-ray tube - Google Patents

Abstract

1385745 Colour television tubes RCA CORPORATION 1 May 1972 [14 Jan 1972] 20047/72 Heading H1D A colour television tube of the shadow mask type using three co-planar beams, is provided with a deflection yoke adapted to produce a pin cushion shaped horizontal deflecting field which causes under convergence at extreme horizontal deflection, and a barrel-shaped vertical deflecting field which causes over-convergence at extreme vertical deflection; and the electron gun is adapted to produce a spacing between the beams at the centre of the deflection yoke not greater than 0À2 inch. Dynamic convergence arrangements are then unnecessary but may be provided for larger tubes. The electron gun may comprise three individual cathodes and common G1 to G4 electrodes provided with apertures for the beams; the outer apertures of the final electrode may be surrounded by magnetically permeable material such as nickel iron to partly screen the outer beams from the deflection fields and thereby equalize the raster sizes for the three colours. The deflection yoke is as described in Specification 1385747 and is preferaby toroidal but saddle coils may be used. The shadow mask may be provided with elongate apertures, and the fluorescent screen may comprise stripes of different colours.

Description

The invention relates to television, namely to a cathode ray tube for reproducing a color television image.

The purpose of the invention is to increase the linearity of the raster over the entire screen of the cathode ray tube.

FIG. 1 shows a three-color receiving electron beam tube, a longitudinal section; in fig. 2 - electronic searchlight assembly of a three-color receiving cathode ray tube.

The three-color electron beam receiver tube contains a vacuum flask 1, a deflecting system 2, an assembly of 3 electronic projectors, a phosphor layer 4, a shadow mask 5, control electrodes 6 and a cylindrical electrode 7 ..

Tricolor receiving electron tube works as follows.

Node 3 electronic spotlights located in a vacuum flask 1, forms three electron beams. The electrons emitted by the cathodes converge at the center of the front glass in the absence of a deflection sweep system. In large color kinescopes, it may be necessary to provide a coma correction, for correcting which a cylindrical electrode 7 is placed around electrodes 6. As a result, the field deflection effect is aligned with three beams, resulting in three equal-sized rasters. The distance between adjacent rays in the plane passing through point C is denoted by the letter S (Fig. 1). The letter c indicates the deflection plane of the deflecting system. S is measured in the deflection plane remote from the node 3 of the electronic projectors, which provides the required distance measured in the plane located half way along the length of the deflecting system 2. The ratio .S and the spacing intervals of the beam-forming electrodes of the node of electronic projecters 3 can be determined trigonometrically by measuring the distance between the holes of the electronic spotlight assembly 3 and the center distance of the deflecting sietem 2 from the holes along the path to the screen of the cathode ray tube where the rays converge. The plane of deflection C was usually in the plane which halves the path along the longitudinal axis of the deflecting system at a right angle to it. At a distance S not exceeding 0.2 inches, there is no need to introduce a correction for coma, if the diagonal of the CRT screen is not larger than 1A inches. If a CRT with a large screen size is used, the coma effect becomes proportionally larger and is eliminated when using node 5 of electron spotlights, in which the spotlights are arranged horizontally (Fig. 2). In this case, the rays are arranged in a row. And the vertical orientation of the beam is not critical, since the phosphor elements extend in the vertical direction on the CRT screen, and there is no need to control the permissible deviations in the vertical direction of the rays, as they always fall on the desired color in the vertical direction. direction. The elongated slit diaphragms in the shadow mask 5 provide higher bandwidth and increase the output optical radiation of the kinescope, resulting in a very small distance S luii, which is used for complete convergence of the rays.

The electron beam tube assembly of 3 electronic spotlights located in a row, in combination with the shadow mask 5 with elongated diaphragms located in front of alternating phosphor elements, does not require dynamic convergence and, therefore, there is no ungrouping of three beams, i.e. magnifications between the three rays when they deviate from the center of the raster.

Claims (1)

Invention Formula A three-color electron tube receiver tube containing a vacuum flask, on the outer side of the neck of which a deflection system is located, and inside the neck of a vacuum assembly of electronic spotlights, which are arranged in a horizontal plane, while on the screen of the vacuum bulb on the inner side are sequentially arranged. of successively repeating triads of phosphor elements of three different colors, and a shadow mask with openings matching 3112 with phosphor elements, In front of the corresponding groups of phosphor elements of three different colors, the deflecting system is located between the shadow mask and the assembly of electronic projectors, on the outputs of which the control electrodes are sequentially arranged, in order to increase the linearity of the raster across the screen -beam tube control electrodes contain at least one common cylindrical 44 electrode with three holes to form and reduce three electron beams, and the distance is m waiting for projections of electron beams onto a plane located at half the distance between the ends of the deflecting system should not exceed 0.2 inch (0.508 cm), while the deflection windings are designed to create vertical positive isotropic astigmatism and horizontal negative isotropic astigmatism .