GB1067754A - Cathode ray tube - Google Patents

Abstract

1,067,754. Cathode-ray tubes. EGYESULT IZZOLAMPA ES VILLAMOSSAGI RESZVENYTARSASAG. Oct. 17, 1963 [Nov. 19, 1962], No. 41108/63. Heading H1D. A post - deflection acceleration cathoderay tube, having two pairs of deflection plates, includes a postdeflection acceleration electrode in the form of a conductive helix 10 extending over only a fraction of the distance from the second pair of deflection plates 9 to the screen 8; a plane screening electrode 22 arranged in front of the deflection plates 9 and in the space surrounded by the electrode 10, to screen the deflection system from the accelerating field; and a further post-deflection acceleration electrode which extends between the first electrode and the screen, and which may be in the form either of an uninterrupted coating 4 on the inner surface of the tube, or of a second helical electrode (26, Fig. 3(b), not shown) having its ends connected to external leads (27, 29), which may be connected together in one mode of operation. The helix 10 extends over only 10% to 30% of the distance from the deflection plates to the screen, and in the embodiment of Fig. 3(b) (not shown) the second helix is of larger pitch and of smaller resistance, whereby in either embodiment, the main post-deflection acceleration takes place over a restricted portion of the electron path. The arrangement permits the use of an increased post-deflection acceleration ratio, and reduces the dependence of deflection sensitivity on post-deflection acceleration potential: the action of the tube is discussed in terms of mutually compensating electron lens action, and dimensional and operating parameters are given. The screen electrode 22 may be a mesh, or an electrontransmitting metal foil.