Patent GB-873321-A (GB)
Title: Improvements in or relating to apparatus for generating a simulated flight display
Inventor: BOWLES DONALD CLIVE
IPC: G09B9/30
Filed: 1958-12-05
Abstract: 873,321. Cathode-ray tube circuits. AVIATION, MINISTER OF, and BUSH & RANK CINTEL Ltd. Dec. 7, 1959 [Dec. 5, 1958], No. 39275/58. Class 40(7) [Also in Group XXXIII] Apparatus for generating a simulated flight display comprises means for generating a first set of cyclically repetitive control signals to control the deflexion and intensity of a cathode-ray tube (C.R.T.) beam to develop on its screen a horizon line of effectively infinite length of which the position and attitude respectively represent the pitch and roll of the aircraft and means for generating a second set of repetitive control signals to control beam deflexion and intensity to develop a display comprising a series of track lines each parallel to the horizon line and their lengths and positions in the display suggesting the altitude and yaw of the aircraft and which vary from one repetition of the display to the next to suggest aircraft speed. The apparatus may include means for causing the beam to trace characters at the zenith or nadir positions when in view. Fig. 1A illustrates the form of display when the aircraft is flying level and with no yaw; the display produced at each repetition differs in that the track lines are displaced downwards and lengthened, to give the effect of a ladder moving towards the observer from the horizon; the apparent rate of movement is arranged to be related to aircraft ground speed. Further figures illustrate the forms of display when flying nose down, left wing banked down, at low and high altitudes, and yawed to the right, Figs. 1B-1F (none shown). Timer 1 causes horizon line generator 2 and a track lines generator 3 to operate alternately, the latter including potentiometers 4, 5 for setting in altitude and ground speed information respectively. The generator outputs are combined in unit 6 and fed to amplifier 7 which sets in the yaw information from potentiometer 9 and the amplifier output is fed to sine/cosine resolver 8 which is adjusted in accordance with roll and the outputs from which are fed to horizontal and vertical deflection amplifiers 13, 16 which receive additionally pitch information from potentiometer 11 via sine/cosine resolver 12. C.R.T. beam intensity modulation is controlled by circuit 17 having inputs from the timer and the track lines generator. The track lines display may be formed by deflecting the beam along spaced lines extending completely across the tube screen and brightening appropriate portions thereof by signals from the track lines generator; in the detailed embodiment described with reference to Figs. 3 and 4 (neither shown) the magnitude of beam deflexion is controlled and the time of line traverse is arranged to be independent of line length. For rotation of the display to simulate aircraft roll the resolvers may be replaced by rotation of the deflexion coil assembly. The detailed embodiment includes arrangements for displaying a symbol + to represent zenith and nadir (when in the field of the pilot's view), a pulse being applied in the latter case to the C.R.T. focus electrode to defocus the spot at the centre of the symbol.