Abstract: Iron/nickel alloy having a low coefficient of expansion, the chemical composition of which comprises iron, nickel, manganese, silicon, calcium, magnesium, less than 0.005% of aluminum, less than 0.001% of sulfur, less than 0.01% of oxygen, less than 0.005% of nitrogen, and less than 0.

Abstract: An iron-nickel alloy useful for the manufacture of a stretched shadow mask, the chemical composition of the iron-nickel alloy containing by weight: 69%.ltoreq.Ni.ltoreq.83%, 0%.ltoreq.Mo.ltoreq.7%, 0%.ltoreq.Cu.ltoreq.8%, 0%.ltoreq.Co.ltoreq.1.5%, 0%.ltoreq.W.ltoreq.7%, 0%.ltoreq.Nb.ltoreq.7%, 0%.ltoreq.V.ltoreq.7%, 0%.ltoreq.Cr.ltoreq.7%, 0%.ltoreq.Ta.ltoreq.7%, 0%.ltoreq.C.ltoreq.0.1%, 0%.ltoreq.Mn.ltoreq.1%, 0%.ltoreq.Si.ltoreq.1%, 0%.ltoreq.Ti.ltoreq.1.2%, 0%.ltoreq.Al.ltoreq.1.2%, 0%.ltoreq.Zr.ltoreq.1.2%, 0%.ltoreq.Hf.ltoreq.1.2%, S.ltoreq.0.010% the balance being iron and impurities resulting from smelting, the chemical composition furthermore satisfying the relationships:Co+ni+1.5.times.Cu.gtoreq.79.5%; 3.times.(Co+Ni)-2.times.Cu.gtoreq.206%; Co+Ni+7.times.Cu.ltoreq.130%; 7.times.(Co+Ni)+2.times.Cu.ltoreq.581%; Mo+W+Nb+V+Cr+Ta.ltoreq.7%; Ti+al+Zr+Hf.ltoreq.1.2%; C+Mn+Si.ltoreq.1%; 80.5.ltoreq.Co+Ni+0.80.times.Cu.ltoreq.81.7%.

Abstract: Shadow mask and process for manufacturing a shadow mask made of an iron/nickel alloy in which: a foil perforated with holes is provided, the foil is subjected to a heat treatment in order to obtain grains whose size, as defined by the ASTM standard, is greater than or equal to ASTM 7, the foil is formed in order to give it the shape of a shadow mask.

Abstract: To avoid the deflection phenomenon of the red and blue spots of a trichromatic tube with in line cathodes, as a function of a variation of the focusing voltage, the holes corresponding to these two colors are enlarged over a distance of about 0.1 to 0.2 mm.

Abstract: Electron gun for cathode ray tube, the electrostatic lenses of which comprise an electrode that remains at a high voltage after shut-down of the power supply of the tube, wherein in order to reduce the effect, apparent through an interference glimmer upon the screen on the K cathode of the high voltage remaining on the electrode after shutdown of the power supply, means for masking this voltage are provided that form part of an electron gun electrode of intermediary position between the first high voltage electrode and the cathode, and wherein preferably, the intermediary electrode has an elongated form according to the axis of the gun with two end walls, of which that turned towards the cathode has a greater thickness than the thickness of the opposite wall.

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.