GB841373A - Improvements in cathode ray tubes - Google Patents

Abstract

841,373. Cathode ray tubes. RADIO CORPORATION OF AMERICA. Aug. 29, 1957 [Sept. 17, 1956; Dec. 24, 1956], No. 27303/57. Class 39(1). A cathode ray tube comprises a cathode 24, a grid electrode 30 having a centrally apertured plate 32 adjacent thereto, a first accelerating electrode 36 with a centrally apertured plate 38, a second accelerating electrode comprising a tubular member 41 terminating rearwardly in a reduced tubular neck 46 with a completely open end, the interior diameter of the tubular neck 46 being from one to five times the diameter of the aperture 40 in the plate 38, the rearward end of the neck 46 being spaced from the plate 38 by a distance of 40 mils per five kilovolt potential difference between the electrodes 41, 36 and a principal focussing field forming means for the electron beam adjacent the forward end of the tubular member 41. Preferably the reduced tubular neck 46 has a length, free from projecting lips or plates, equal to its diameter. As shown the plate 32 is formed by the bottom portion of a cup-like structure 30 facing rearwardly in which is insulatingly supported the cathode 24, and the plate 38 is formed by the bottom portion of a cup-like structure 36 facing forwardly into which projects the neck portion 46. The principal focusing field forming means comprises a pair of apertured elements 48, 54 positioned at the opposite ends of a third apertured element 50, the elements 48, 54 being insulatingly supported for receiving a high potential with respect to the element 50. The electrodes 30, 36 and 41 are supported from glass rods 60 and the electrodes 43, 50 and 52 are supported from similar rods 58, the electrode 43 being telescoped into tight fitting engagement with the tubular member 41. In another embodiment, the length of the gun is shortened by slotting the electrode 43 through which pass studs 56 joining the member 41 to its supporting rod 60.