Cathode-ray tube maintaining accurate focusing - has layer on inner surface of hollow tube shielded from getter arrangement to prevent unwanted deposition

摘要

The cathode-ray tube (1) has an envelope comprising on the one side a luminescing screen and on the other side a neck portion (2). An electron gun (3) is positioned in the neck portion (2) and includes a beam-forming portion and a focusing structure (10). The focusing structure (10) includes an open-end hollow tube (12) of an electrically insulating material, having an inner surface on which a layer (14) of a material having a high electrical resistance is deposited and a getter arrangement (44) provided in the envelope. The layer (14) on the inner surface of the hollow tube (12) is shielded from the getter arrangement (44). At that end of the hollow tube (12) that faces the luminescing screen an open-ended auxiliary tube (45) is arranged whose axis is located in the extension of the axis of the hollow tube.