On the use of getters in TV cathode-ray tubes

Abstract

Since some years, to increase the pictures brightness, the Kinescopes have been aluminized. But the unavoidable heavy aluminium thickness in the centre of the screen is visible, as dark centre, at low ultor voltage. For this reason, the minimum operating voltage is indicated on each type data. It is however easy for the Kinescopes manufacturer to remain in the allowed limits taking account that the Getter Baryum layer, which has a higher atomic mass, is more opacious than the aluminium film and can increase the defect occasioned by the bad uniformity of this one, affecting the colour uniformity of the screen at low ultor voltage. It appears convenient to direct, during the getter flash the Baryum molecules, in order to see they deposit out of the screen area. A good solution has been found by the S.A.E.S. who supply a ring getter with very efficient deflector. The rational use of this getter introduces special cautions, otherwise the new getter type will be worse than the old one. During this communication, some test results will be given illustrating perfectly this theory.