Patent GB-911843-A (GB)
Title: Display means for visual monitoring of a plurality of sensed conditions
IPC: G08B26/00
Filed: 1959-04-20
Abstract: 911,843. Cathode-ray oscilloscopes. AVIEN Inc. April 20, 1959 [April 21, 1958], No. 13422/59. Class 40 (7). A plurality of signal voltages corresponding to a plurality of physical conditions and an adjustable reference voltage are applied sequentially to the Y plates of a cathode-ray oscilloscope by means of a commutator 27 synchronized with the X timebase. As described, the physical conditions are the temperatures at different points of a number of aero engines but they may comprise vibration, fuel consumption, r.p.m. pressure, humidity or pH concentration. As shown, the input signal voltages from thermocouples 12 ... 26 are applied to segments 12A ... 26A of the commutator 27 and the reference voltage from a calibrated potentiometer 32 is applied to a larger segment 28. The sequential signals from the segments 12A ... 26A are applied to the Y plates of the C.R.T. 44 through a compensating thermocouple 31 and an amplifier 40 and the output from the segment 28 is applied to the input of the amplifier 40. Alternatively the compensating thermocouple 31 and its oven 31A may be replaced by other compensating means such as disclosed in U.S.A. Specification 2,877,650. A triangular timebase voltage, Fig. 2 (not shown), is produced by a circular potentiometer 54 and the commutator 27 and potentiometer 54 are driven by a motor 39 so that the reference voltage is applied to the C.R.T. during the backstroke of the timebase to produce a continuous calibration trace whose vertical position is controlled by the potentiometer 32. Each input signal produces a short horizontal trace which is brighter than the calibration trace and during the intervals between adjacent signal traces the input to the vertical amplifier 40 is earthed by means of a commutator 48 having segments 50 corresponding to the spaces between the segments 12A ... 26A of the commutator 27. Any particular group of signal traces may be enlarged, Fig. 6 (not shown), by adjusting the X and Y shift and amplitude controls. In order to indicate the average value of a group of signal voltages, e.g. those from thermocouples 12-18, the leads from said thermocouples are connected together by a relay 53 controlled by a manual switch 55 and the average value will then be indicated by a broken horizontal trace, Fig. 4 (not shown). If a more elaborate averaging circuit of known form is required, additional switches are provided, Fig. 5 (not shown), to connect the signal inputs to the averaging circuit and to connect the output from the averaging circuit to each of the signal segments of the commutator 27; in this case the reference voltage is applied to the averaging circuit during the timebase back-stroke period. In a modification, Fig. 7 (not shown), the timebase is generated by integrating the output from a bistable multivibrator which is triggered on and off by pulses produced by an additional commutator and in a further modification, Fig. 8 (not shown), the input signals are applied to one set of alternate commutator segments and the reference voltage is applied to the other set of alternate segments which are connected together so that a broken reference trace is produced during the forward stroke of the timebase.