GB833999A - Improvements in or relating to cathode ray tubes - Google Patents

Abstract

833,999. Cathode-ray tubes. NATIONAL RESEARCH DEVELOPMENT CORPORATION. April 27, 1956, No. 13054/56. Class 39(1). In a cathode-ray tube for displaying information in polar co-ordinates, e.g. for use in radar, the beam 12, Fig. 2, is directed towards the centre of a screen 22, is deflected into a path lying in a plane parallel to the screen and is deflected at progressively varying points along this path into impact with the screen, the beam being meanwhile rotated about its initial axis. The beam is deflected on to the screen by annular transparent strip electrodes 34 to which negative potentials are sequentially applied. The strips are secured to a transparent insulating plate 30. The beam is deflected from its original path by electrodes 40, 42 shaped as shown or, in modifications, shaped as hemispheres 60, 64, Fig. 3, or as coaxial conical frusta 70, 72, Fig. 4. The beam is rotated by pairs of deflecting plates 7, 9. In Fig. 5, the beam is both deflected and rotated by a cylinder 80 which comprises a pair of curved electrodes 84, 86 and is rotated by means of the bar magnets 94, 96. The electrodes 84, 86 are energized through slip rings 88, 89. In a further modification the beam is initially projected in a path parallel to the plane of the screen and is deflected through 90 degrees to pass between the electrodes 84 and 86. The positions of the screen 22 and annular deflection electrodes 3 may be interchanged in each of the embodiments and the screen and annular deflection electrodes and also the tube envelope may be of segmental shape instead of extending through a small circle.