GB1306155A - - Google Patents

Abstract

1306155 Image pick-up tubes GENERAL ELECTRIC CO 29 May 1970 [11 June 1969] 25981/70 Heading H1D A camera tube (e.g. a Vidicon tube) comprises a cylindrical glass envelope 4, metallic field mesh 20 adjacent electron beam target 10 and between the target and electron beam generating means, the mesh being secured to and spanning first metal ring 30 sealed in peripheral engagement with an open end of the envelope, second metal ring 60 with glass faceplate 6 peripherally sealed, and ceramic spacer 50 between the rings having metallized faces bonded to the rings (e.g. by solder, such as a Ag-Cu alloy). The field mesh may be decelerating electrode and ensures orthogonal landing of the beam on the target, the above structure ensuring a parallel configuration at a separation determined by the ceramic spacer 50. Mesh 20 may be 1000 lines/inch and welded for example, to metal flange 24 with portion 26 welded to ring 30 or portion 26 may be integral with ring 30. Ceramic spacer 50 may be forsterite, zircon, steatite or alumina, high strength alumina with >85% aluminium oxide content being preferred. Faceplate 6 may be a conducting glass or may support a conducting layer contacting ring 60 and electrode connections may be applied to terminal ring 60. Deflecting electrodes (14), (Fig. 1, not shown), inside or on the envelope control the scan over photoconducting target (10) the above construction enabling accurate placement of the deflecting electrodes. When magnetic deflection is used, the inner wall of envelope 4 may be coated with a continuous metal layer, and mixed B or E focus and deflection fields may also be used.