Patent GB-1010346-A (GB)
Title: Control apparatus for lamp bank displays
IPC: G04G9/00
Filed: 1964-03-11
Abstract: 1,010,346. Control circuits for lamp bank displays; electric selective signalling. AMERICAN SIGN & INDICATOR CORPORATION. March 11, 1964 [March 22, 1963], No. 10392/64. Headings G4H and G5C. [Also in Division G3] Individual groups of electric lamps forming parts of an array of lamps are selectively energized through gate signal controlled electronic switch means, a diode matrix interconnecting the groups ensuring that only groups required are illuminated at any one time to display characters etc. Particular embodiments are an arrangement involving an electronic clock and a temperature responsive servo-mechanism, whose indications are alternately displayed on an array indicating three characters or digits at once, and a traffic sign displaying a number representing a speed limit and variable. An arrangement for varying intensity of illumination of the lamps in response to ambient light conditions is described. Diode matrix.-Fig. 4 shows three lamp banks comprising lamp groups 109, 103, 97 each wired in series with an S.C.R. (silicon controlled rectifier) 108, 102, 96 across a pulsating D.C. supply 13. Lamps are illuminated in response to gate signals applied to S.C.R's 108 &c., the S.C.R's acting as thyratrons. For example a trigger pulse signal, comprising a regular series of pulses, is received on one of ten inputs 92 and transmitted by diodes 94 and resistances 95 to one or more of S.C.R's 96 thereby triggering them and illuminating certain lamp groups 97 to delineate say a numeral representing the minutes digit of the time. Diodes 94 prevent the signal being fed from one input 92 into another via the connections to resistance 95, thereby preventing all lamp groups 97 being lit for a signal on any input 92. Intensity control.-Ambient light conditions are monitored by a photo-cell (Fig. 2, not shown) which controls the phase of an oscillator and hence the phase of a pulse signal produced by an S.C.R. and fed via either an electronic clock or temperature responsive servo-mechanism to the appropriate input 104, 98, 92 (or 135, 132, Fig. 4) to trigger the appropriate S.C.R's in the lamp supply circuits (Fig. 4). The pulses in supply 13 are of sufficient amplitude to cut off S.C.R's 108, 102, 96 every pulse cycle and depending on the relative phases of these and the trigger pulse signal the lamp groups are illuminated for a variable part of each supply cycle and their intensity thereby controlled. Electronic clock.-A timing motor controls a switch which produces one pulse every minute by charging and discharging a condenser (Fig. 2, not shown). The pulse is fed into line 59 (Fig. 3) to amplifier 69. A minute ring counter 23 comprises ten flip-flop circuits 70 (only three shown) and these are triggered in turn by successive pulses. Every ten minutes, a pulse is transmitted from the end circuit 70 to amplifier 75 which is connected to a tenminute ring counter 22 comprising six flip-flop circuits 76. Similarly an hour ring counter 21 may comprise twelve or twenty-four flip-flop circuits 82. The various gate transistors 73, 79, 86 are arranged to pass the trigger pulse signal described above from line 39 to one of output lines 89, 90, 91 when their particular flip-flops are conducting. The lines 89, 90, 91 supply inputs 92, 98, 104 (Fig. 4) respectively; so as long as line 39 supplies a pulsating trigger signal to the clock the hours, ten-minutes and minutes will be displayed as numerals on three adjacent lamp banks. Fig. 2, not shown, illustrates an emergency battery supply to the clock, and means whereby pulses may be propulses may be produced manually, by discharging a condenser through switches, and fed to any of lines 64, 67, 59 to re-set the three digits displayed on the lamp banks. Temperature-responsive servo-mechanism.-A switch is supplied (Fig. 2, not shown) whereby the trigger pulse signal triggering S.C.R's 108, 102, 96 to energize selected lamp groups (Fig. 4) is fed for alternate periods either to the electronic clock or to a mechanism (Fig. 5) whereby the lamp banks display either time or temperature. A temperature sensor 25 (Fig. 5) feeds a self-balancing bridge 110-113 whose motor 112 controls, via gears and lost-motion devices (Figs. 6-9, not shown), two rotary switches 114, 115 which turn respectively one step for every degree and for every ten degrees. The trigger pulse signal is fed from line 38 to the rotor 116 of switch 115. If the temperature is above 0‹ F., the signal passes to the contact 119 leading to the appropriate input 135 (Fig. 4) for displaying the ten degree number on the lamp groups 109, and also via a strip 121 and line 122 to a point 123 on rotor 124 engaging contacts 125. A temperature below zero, would place rotor 116 so that the signal would pass through contacts 120 and thence to lamp groups 109 and also via a strip 126, leading to a line 137, which controls an S.C.R. 138 (Fig. 4) illuminating lamps 139 to delineate a minus sign, and to point 128 on rotor 124 engaging an inside row of contacts 129, interconnected with contacts 125 for displaying negative temperatures. An arrangement of two switches mounted to engage a wheel on the rotor 124 ensures that the rotor turns to always engage one of contacts 125, 129. The degree sign is displayed by right-hand lamp groups 97. Modifications.-Figs. 10-13 (not shown) show a road sign displaying a variable speed limit and an alternative switching circuit for lamp groups in which each lamp groups is placed in series with diodes in a matrix, S.C.R's switching power to the diodes appropriate to the required display.