Abstract: A cathode ray tube has an electron gun oriented along an axis (Z), comprising a quadrupolar device which comprises three electrodes (5, 6, 7). Each electrode possesses a central aperture, a right lateral aperture and a left lateral aperture all three substantially rectangular. The centers (c5.1, c7.1) of the central apertures of the three electrodes are aligned along the axis (Z) of the gun. The centers (c6.1, c6.3) of the left and right lateral apertures of the second electrode (6) are situated along respectively a first axis (z1) and a second axis (z3) that are parallel to the axis (Z) of the gun. The centers (c5.1, c7.1) of the left and right lateral apertures (5.1, 5.3, 7.1, 7.3) of the first and/or of the third electrode (5,7) are offset with respect to the axes (z1, z3) passing through the centers of the apertures of the second electrode. Such an arrangement makes it possible to correct the MODEC defects.

Abstract: A cathode-ray tube has an electron gun with a main focusing lens, wherein each electrode comprises a rectangular aperture whose large dimension is along the horizontal axis (Ox) and terminating at its two ends in two identical semi-ellipses of order n that are symmetric with respect to the axis of the gun (Z).

Abstract: The invention relates to an electron gun for cathode ray tubes comprising a cathode emitting an electron beam according to a determined propagation axis, and, aligned in series according to this axis, successively a first electrode, a second electrode. The first electrode comprises a first plate featuring rectangular apertures, the edges of which have a constant thickness. The second electrode comprises a second plate featuring circular apertures of diameter ? greater than the largest dimensions of the rectangular apertures. They will preferably be: 0.7 mm?W?0.9 mm 0.5 mm?H?0.7 mm 0.5 mm???0.9 mm and the distance d between the first and second electrodes such that: 3.34 mm?d?0.45 mm Applications: Electron gun for cathode ray tube.

Abstract: Electron gun for cathode ray tube comprising aligned in series along an axis XX? an electron-emitting cathode K, electrodes G1 and G2 for the formation of an electron beam, a prefocusing electron lens G3, G4, G5, a first quadripolar device G7, G8 electrically controlled in a dynamic manner in synchronism with the screen scan so as to correct beam focusing defects at the screen edge, a main electron lens G8–G9 making it possible to focus the electron beam onto a screen. It also comprises a second quadripolar device G5, G6, G7situated between the prefocusing electron lens G3, G4 and the first quadripolar device and comprising electrodes G5, G6, G7exhibiting rectangular apertures. Those of G5 and G7 are parallel and those of G6 are orthogonal to those of G5 and G7. The electrodes G5 and G7 are placed at a fixed polarization potential, and the electrode G6 is at a polarization potential varying in synchronism with the screen scan.

Abstract: The invention relates to a cathode-ray tube having an electron gun with a main focusing lens, in which the aperture of each electrode comprises a rectangular aperture whose large dimension is along the horizontal axis (Ox) and terminating at its two ends in two identical semi-ellipses of order n that are symmetric with respect to the axis of the gun (Z) and of formula: ( x a ) 2 n + ( y b ) 2 n = 1 in which x=a cosn ?; y=b sinn ?, the parameter n has a value different from 1, a is half the width of the ellipses of order n along the horizontal axis (Ox) and b being half the height of the ellipses of order n along the vertical axis (Oy), x represents the abscissa of a point lying on the ellipse of order n and y is the ordinate of a point lying on the ellipses of order n, ? is an angle which varies in one quadrant between 0° and 90°.

Abstract: The invention relates to a main electron lens for an in-line electron gun, comprising a first, focusing electrode and a second, accelerating electrode which are equipped with optical plates, each provided with a central hole and with two outer holes. The first optical plate is placed at a first distance from the aperture of the first electrode and the second optical plate is placed at a second distance from the aperture of the second electrode. The ratio of the first and second distances is determined by the formula: L1/L2=A11(?Vd)2+A1?Vd+A0+C0×Bias in which: A11, A1, A0 and C0 are constants; ?Vd is the variation in the focus voltage that it is desired for the system to have; and Bias is the bias that it is desired for the system to have.

Abstract: The invention relates to a cathode ray tube having an electron gun oriented along an axis (Z), comprising a quadrupolar device which comprises three electrodes (5, 6, 7). Each electrode possesses a central aperture, a right lateral aperture and a left lateral aperture all three substantially rectangular. The centres (c5.1, c7.1) of the central apertures of the three electrodes are aligned along the axis (Z) of the gun. The centres (c6.1, c6.3) of the left and right lateral apertures of the second electrode (6) are situated along respectively a first axis (z1) and a second axis (z3) that are parallel to the axis (Z) of the gun. The centres (c5.1, c7.1) of the left and right lateral apertures (5.1, 5.3, 7.1, 7.3) of the first and/or of the third electrode (5,7) are offset with respect to the axes (z1, z3) passing through the centres of the apertures of the second electrode. Such an arrangement makes it possible to correct the MODEC defects.

Abstract: Electron gun for cathode ray tube comprising aligned in series along an axis XX′ an electron-emitting cathode K, electrodes G1 and G2 for the formation of an electron beam, a prefocusing electron lens G3, G4, G5, a first quadripolar device G7, G8 electrically controlled in a dynamic manner in synchronism with the screen scan so as to correct beam focusing defects at the screen edge, a main electron lens G8-G9 making it possible to focus the electron beam onto a screen.