ELECTRIC DISCHARGE TUBE HAVING A GLASS- SEALED ELECTRIC LEADTHROUGH AND METHOD OF MANUFACTURING SUCH AN ELECTRIC LEADTHROUGH

摘要

An electric discharge tube, in particular a television camera tube, is provided with a hermetically sealed electric leadthrough which connects a thin-film electrode provided on the inner wall of the tube envelope electrically to an electrically conductive layer provided on the outer wall of the envelope. The leadthrough consists of an aperture in the envelope having a conductive layer provided on the wall of the aperture. The aperture is hermetically sealed by means of a plug of thermally devitrified glass which is provided in the form of a suspension of a devitrifiable glass powder in an organic binder. For the manufacture of the leadthrough the envelope of the tube is subjected to a temperature treatment in which in a first temperature range the binder is fired from the suspension while maintaining an oxygen-containing atmosphere and in a second temperature range the devitrifiable glass is devitrified while maintaining a non-oxidizing atmosphere. This method results in a hermetically sealed leadthrough without excessive oxidation of the thin-film electrode occurring, while the occurrence of deformations of the glass envelope at the area of the leadthrough is avoided.