GB856018A - Electronic apparatus utilizing a cathode ray tube - Google Patents

Abstract

856,018. Cathode-ray tubes. RYDBECK, O. E. H., and STENHARDT, C. M. E. April 29, 1957 [May 2, 1956], No. 13550/57. Class 39(1). In a cathode-ray tube apparatus for obtaining frequency addition or subtraction the beam is deflected in a closed preferably circular path at frequency f, and auxiliary radial deflecting fields are superposed on the closed path by electrodes Hnm and an electrode S 8 , the electrodes Hnm being divided into interleaved groups each with n electrodes a source of multiphase energy, such as a second cathode-ray tube, of frequency f 2 and m phases each phase being connected to a different group of deflection electrodes Hnm to produce the auxiliary radial deflecting fields having m phases and n polepairs, the auxiliary deflection field rotating at a frequency of f 2 /n the output frequency being nf 1 Π# 2 , depending on the relative directions of the beam sweep and rotating field. In Fig. 2 the target comprises a plate S 8 and a plurality of plates Hnm arranged in annular formation which are energised by a six phase supply to produce a rotating electric field which deflects the beam locally on and off the plates S 8 and Hnm. The beam thus oscillates radially, e.g. under the control of 3 volts D.C. and a superposed 3 volts A.C., so that it strikes S 8 or passes through to collector S 10 but does not strike plates Hnm at all. The multiphase waveform applied to plates Hnm is generated by an auxiliary cathode-ray tube 151 in which the beam rotates over target sectors P 1 . . . Pm equal in number to the number of phases to be generated, and is applied to the electrodes Hnm of tube 150 via amplifiers F and condensers C 21 , C 22 , while the D.C. bias is applied to plates Hnm via resistances Rm from source 55-56. A reversing switch Sw enables the direction of rotation of the beam to be reversed. w 2 /2#n = frequency of rotation of multiphase field in tube 150, and the beam rotates at a frequency w 1 /2# in main tube 150, then if w 2 /2#n nequals w 1 /2# and beam and field rotate in same direction there is anly a constant D.C. output. If they are not equal then the output has a frequency n(f 1 Πf 2 /n) according as to whether the directions of rotation are opposite or the same. The device of Fig. 2 can be regarded as a device for shifting the output carrier frequency nf 1 of a conventional frequency multiplier tube to nf 1 Πf 2 according to the position of switch Sw.