Patent GB-1368146-A (GB)
Title: Illuminated display system
IPC: G09B29/10
Filed: 1971-12-03
Abstract: 1368146 Route indicator P SIMON 3 Dec 1971 [3 Dec 1970 15 Nov 1971] 56343/71 Heading G4H An illuminated route indicator comprises a generator assembly 5-7, Fig. 1, for repeatedly supplying consecutive signals 5a, 5b, 5c to lines 1a, 1b, 1c, a destination indicating board 2 having scanning and destination lamps 20, 21, a control 19 for scanning the board by the sequential actuation of lamps 20 in response to the output from assembly 5-7, a display 23 having route-indicating lamps 22 each connected (77, Fig. 2) to a particular lamp pair 20, 21 and a blocking circuit 17 for controlling the illumination of lamps 21, 22. A destination is sought on board 2 by rotating a knob 6 to rotate an apertured disc (Figs. 3, 4, not shown) located between a light source and three photo-cells which provide the pulses 5a, 5b, 5c (with a period of overlap at each changeover between successive lines) ; these are fed to a wave-shaper 7 comprising SCR's 30 and capacitors 34, 36 and 40 to produce pulses 7a-7c which are fed to a relay control circuit 10. This comprises transistors 41-54 which are turned on by the pulses so as to turn off transistor 57 in blocking circuit 17 (so that lamps 21, 22 cannot be lit) and to operate a relay 9 which closes switches 8. The pulses can then be transmitted via 1a-1c to a series of SCR's 68 each of which controls a lamp 20; gate 69a of the first SCR is connected to the positive D.C. terminal 14 (via 13, 67, 66, 64) so that it can be fired by pulse 1a. The first lamp 20 lights, making junction 63 positive to turn on a transistor 59; the positive potential is thereby removed from 69a so that 68 will not be fired again after it has been turned off. The first SCR is connected to the gate of the second SCR; the gate of the latter therefore goes positive and it is fired by pulse 1b, thereby turning off the first SCR. The succeeding SCR's are fired in their turn while the disc is rotating; when rotation ceases so do the pulses, 41-46 then being switched off and 57 being switched on so as to allow the lighting (via terminal 18 and D.C. terminal 15) of that lamp 21 connected to the lamp 20 lit when rotation ceases. The required destination is thereby illuminated on board 2; lamp 21 is connected via 77 to the gate of an SCR 80 controlling the lamp 22 associated therewith: the gate goes positive so that this SCR is fired (A.C. source 81, 82) and the lamp 22 is lit. This lamp is connected to the gate of an adjacent SCR which is fired in turn to light the next lamp; the process continues until all the lamps have been lit as far as a "present position" lamp 4 so as to illuminate the desired route. The generator assembly may incorporate a unijunction transistor pulse generator 212, Fig. 5 (not shown), operated by a bi-stable device (202) to generate pulses upon cessation of rotation of knob 6. A dynamic route indication may be provided by replacing terminals 81, 82 by a transformer 224, Fig. 6 (not shown), fed from a pulse generator (230); the SCR's are grouped in fours and are fed in turn by pulses from (224) output over one of four lines in turn, the output from (230) consecutively firing SCR's 225 to change the tapping on the transformer secondary. A series arrangement of lamps 22 is also described (Fig. 7, not shown).