GB1153891A - Improvements in or relating to Visual Display Apparatus - Google Patents

Abstract

1,153,891. Cathode-ray tube displays. ELECTRONIC & X-RAY APPLICATIONS Ltd. 21 Oct., 1966 [24 July, 1965], No. 31656/65. Heading H4T. In a cathode-ray tube display variations of the magnitudes of some input signals are displayed against a time base scale, e.g. traces 65, 66 (Fig. 4), whilst the magnitudes of other signals are displayed as traces 63, 70 against fixed scales 62, 69. The traces 65, 66 may be produced by the outputs of different electro-cardiographs and traces 63, 70 may indicate the heart rate of the respective patients but signals indicative of other factors may alternatively be displayed. The display is produced by the arrangement of Fig. 1, which utilizes switching circuits 11 ... 18, each comprising a pair of switches simultaneously operated by pulses from a source 30 which switches on the circuits 11 ... 18 successively and cyclically each for a period of 140 Ás at 60 Ás intervals. The outputs of the left-hand switch of each pair, e.g. T3, are connected via conductor 8 and amplifier 4 to the horizontal deflection plates 2 of the display tube and the right-hand outputs, e.g. T4, are connected via conductor 9 and amplifier 5 to the vertical deflection plates 3, 10 so that as source 30 cycles through its switching sequence the horizontal and vertical positions of the beam of tube 1 are determined respectively by the inputs to the left and right-hand switches, e.g. T1, T2. In the case of circuits 11 and 15 the left-hand switch inputs comprise the output of a time base 32 and the right-hand switch inputs comprise the outputs of electro-cardiograph amplifiers 47 and 48 respectively, the output of 48 including a fixed bias so that the respective vertically spaced traces 65, 66 are produced. For circuits 12 and 16 the left-hand switch inputs are derived from potentiometers 41, 44 the - V potential source to which includes a small A.C. component so that a, horizontally elongated trace such as 63 is produced with a similar trace if desired on the right-hand side of the display instead of the display shown. The vertical position of line(s) 63 is then determined by cardiotachometers 49, 50 which supply the inputs of the right-hand switches in 12 and 16. Circuits 13, 14 and 17, 18 are utilized to produce upper and lower limit markers such as 68, 67 the left-hand switch inputs from potentiometers 42, 43 and 45, 46 determining the horizontal position of the traces and the right-hand switch inputs from potentiometers 51, 52 and 53, 54 determining the vertical positions. If desired, one of the latter displays may take the form shown at the right-hand side of Fig. 4 in which the heart rate output of the tachometer is indicated by the length of a vertical line 71 with a desired rate value indicated by horizontal trace 70. A circuit which operates an alarm when the heart rate departs from pre-set maximum or minimum values and which rates may be displayed is described with reference to Fig. 5 (not shown).