Patent GB-1063048-A (GB)
Title: Traffic actuated road signal control system
IPC: G08G1/08
Filed: 1964-05-26
Abstract: 1,063,048. Road traffic signals; electronic counters. LABORATORY FOR ELECTRONICS Inc. May 26, 1964 [May 29, 1963; Jan. 2, 1964], No. 21760/64. Headings G4A and G4Q. [Also in Division H3] A traffic controller of the type using a cyclic switch to determine the various phases is characterized in that the cyclic switch comprises a solid state electronic counter. In Fig. 1 the counter 20 provides a positive potential output on leads 1-8 in turn as it is stepped by an input on lead 52. In positions 7, 8 and 1 the main road green light AG is energized, in position 2 the main road yellow AY, and so on as shown; if switch 155 is moved to its other position, periods 3 and 7 become all red intervals. The intervals are timed by circuit 125 which comprises a capacitor 161 charged through an individual resistance from the current output of the counter 20, and normally connected to a trigger unit 132 which, when fired, re-sets the timing circuit and advances the counter 20 to its next stage. In position 5 (the extendible green period of the cross road B) the timing circuit 125 is re-set by unit 163 each time a demand is registered by contacts 102, and a second timing circuit 107 times a maximum period -starting from the beginning of period 4. (The inhibiting circuit 133 prevents timer 107 being re-set at the beginning of period 5).During other intervals a vehicle demand is stored by memory 104 (which also stores a re-call signal if period 5 is terminated by the maximum timer 107) the output of which is inverted and fed to AND gate 119. Thus, if there is no demand, there is an output from gate 119 during period 1 which inhibits gates 123 and 196 thereby preventing the operation of the timing circiuts so that the controller rests in position 1. The controller can also be brought to rest in this position by an external signal supplied to line 118. Pedestrian control.- A pedestrian-operated switch 112 stores a call in memory 113 which, during periods 2 or 3, causes capacitor 152 to charge and trigger circuit 153 which steps on a four position counter 40 from its rest position 11 to position 12. During periods 4 and 5 (B' road green period) the capacitor 152 charges through AND gate 148 to time a WALK period, after which the counter 40 steps to position 13 and a flashing DON'T WALK period is timed; the counter 40 is then stepped to a skip position 14 and rest position 11 when the steady DON'T WALK sign is displayed. Alternative controllers.-In the controller of Fig. 4 (not shown), the 8-step counter 20 is replaced by a 9-step counter (263) and the 4-step switch 40 is replaced by a 3-step switch (262). A pedestrian walking signal (AWK) is displayed automatically in one direction during intervals 8 and 9 (part of the A street green period) in addition to the pedestrian controlled signal (BWK) which may be displayed on demand in the other direction during interval 4 (part of the B street green period). Another controller, Fig. 7 (not shown), can operate in one of five modes, giving variable degrees of vehicle and pedestrian control, according to the settings of 24 switches (S1- S24). Some or all of the switches may be jumper connections which may be in printed circuit form, and controller functions may be added or eliminated by substituting one printed circuit board for another. Ternary electronic counter. Fig. 5. At a given time, one of the three transistors 358- 360 of the first stage 356 is non-conducting and the other twoconducting. Application of a negative pulse on line 355 from input circuit ST advances the counter one step, and the final transistor 360 is coupled to the next stage 356<SP>1</SP> of the counter. Output circuits 420-428 provide a positive potential on the line corresponding to the state of the counter. A transistor 430 ensures that the counter is set to state 2 when first switched on, and an input line 279 allows the counter to be set to state 6 at any time.