GB1280952A - Image converter tube - Google Patents

Abstract

1280952 Image converter tube PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 10 March 1970 [13 March 1969] 11438/70 Heading H1D An image converter tube (light and X-ray inputs) comprises a cylindrical glass envelope 5, spherical glass window 6 with photocathode 1, the latter in combination with a phosphor layer for X-radiation input, phosphor screen 2, and an electron optical focusing system including electrode 4 with a first part provided as a coating on the inner envelope surface and a second part comprising a cylinder extending from the window end of the first part towards the window, the second part having a smaller outside diameter than both the first part and the inside diameter of the seal and electrically insulated from the latter. Ring 19 of glass or other heat resistant insulating material may be provided and increases the insulation, the ring being sealed to the glass envelope, or in the right hand of the figure, to the lower part of the two part 17, 18, metal ring, by means of a vitreous material, e.g. glass enamel, of lower m.p. than ring 19. The material 20 covers also the seal between the envelope and ring. The conductive coating may be provided by vapour deposition of metal particles with the exception of annular end 21 and the photocathode formed prior to the sealing together of the two tube portions. In Fig. 2 (not shown), one part of the metal ring may have a channel shaped section, one limb being coated with vitreous material 20, covering the ring-envelope seal in addition. Alternatively, the envelope may be interrupted with a second metal ring (25) (Fig. 3, not shown) joined to metal sleeve (23) forming a prolongation, the conductive coating terminating at the second ring and the sealing ring may be at cathode potential. Anode 3 includes conical portion 12 with spherical portion 13. A thin Al coating 16 reflects emitted light to the viewer.