GB457757A - Television cathode ray tube - Google Patents

Abstract

457,757. Television cathode-ray tubes. RADIOAKT.-GES. D. S. LOEWE, 10, Wiesenweg, Steglitz, Berlin. March 4, 1935, No. 6688. Convention date, March 3, 1934. [Classes 39 (i) and 40 (iii)] In a television tube highly evacuated or filled with gas at less than 5À10<-5> mm. pressure and comprising deflecting plates 13 .. 16 axially spaced from the electrodes of an electrostatic electron lens, the electrode 12 next to the plates in the direction away from the picture screen 8 acts as an anode accelerating the ray and forming part of the lens and comprises a disc 12<1> having an aperture provided with a tubular extension 12<2> towards the screen 8, the electrode 12 preferably terminating in a further disc 12<3>. The electrode 12 is coaxial with and spaced from a tubular electrode 9 with internal diaphragm 10 as described in Specification 457,846. The cross-section of the electrode 12 is sufficient to pass the ray without obstruction and the extension 12<2> is so long that the lens field is screened from the deflecting plates and that the electrons are uniformly accelerated to the anode voltage, the ratio of this length to the shortest distance apart of the deflecting plates 13, 14 being greater than 1, for example, 1À5. The disturbance of the lens field by the varying deflecting voltages and trapezoidal deformation of the picture are reduced by arranging and operating the deflecting plates as described in Specification 452,650 and by associating with the edges of the deflecting plates auxiliary electrodes 13<1> as described in Specifications 449,245 and 457,848. An earthed metal coating 19 and iron armour 34 are provided. The deflecting plates of each pair are mutually inclined and are mounted and centred by end plates. The diaphragm 6 is connected to the anode 12 and the electrode 9 is at a lower potential. The Specification as open to inspection under Sect. 91 comprises also the subjectmatter of Specifications 456,717 and 456,331, auxiliary electrodes associated with the aperture in the electrode 12 as described in Specification 457,848, and an electron lens in which an apertured disc is spaced from a tubular electrode by a distance at least equal to, and preferably twice, the diameter of the tubular electrode. This subject-matter does not appear in the Specification as accepted.