TRAFFIC SIGNAL CONTROL SYSTEM
First Claim
1. In a traffic control system for turning lights at a plurality of intersections on and off in response to command signals from a master controller, the combination comprising, means at the master controller for generating and transmitting data signal trains, each train including an intersection address set of signals and the same intersection command signals, a local controller at each intersection, each local controller including means for detecting the address set for that intersection and producing an address signal, means for storing the command signals in a signal train addressed to the intersection and producing a valid message signal, switching means for controlling ac line power to the intersection lights, means for detecting the zero crossing of the ac line power and producing an ac zero crossing signal and means for controlling said switching means in response to said address signal, said valid message signal, said stored command signals and said ac zero crossing signal, whereby the lights are energized by ac line power only following storage of valid command signals addressed to the intersection and said energization commences and terminates only at zero crossings of the ac line power, tending to eliminate current surges in the ac power line when the lights are switched on or off.
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Accused Products
Abstract
An automobile traffic signal control system controls traffic signals (lights) at a plurality of traffic intersections by way of a master controller which communicates with a local controller at each intersection and transmits pulse trains in sequence to the receivers at all the intersections, whereupon the intersection to which a specific pulse train is addressed stores the pulse train and uses each specific pulse in the train to control a specific light or signal at that intersection. In this manner, all lights and signals at all intersections are specifically each controlled by a specific pulse in a specific pulse train transmitted by the master controller to the local controllers at the intersections.
15 Citations
1 Claim
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1. In a traffic control system for turning lights at a plurality of intersections on and off in response to command signals from a master controller, the combination comprising, means at the master controller for generating and transmitting data signal trains, each train including an intersection address set of signals and the same intersection command signals, a local controller at each intersection, each local controller including means for detecting the address set for that intersection and producing an address signal, means for storing the command signals in a signal train addressed to the intersection and producing a valid message signal, switching means for controlling ac line power to the intersection lights, means for detecting the zero crossing of the ac line power and producing an ac zero crossing signal and means for controlling said switching means in response to said address signal, said valid message signal, said stored command signals and said ac zero crossing signal, whereby the lights are energized by ac line power only following storage of valid command signals addressed to the intersection and said energization commences and terminates only at zero crossings of the ac line power, tending to eliminate current surges in the ac power line when the lights are switched on or off.
Specification
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- Resources
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Current AssigneeJohn Francis Ward, Kenneth H. Molloy, Mark Benson
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Original AssigneeJohn Francis Ward, Kenneth H. Molloy, Mark Benson
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InventorsMolloy, Kenneth H., Ward, John P., Benson, Mark
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Primary Examiner(s)Borchelt, Archie R.
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Assistant Examiner(s)Nussbaum, Marvin
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Application NumberUS05/268,614Time in Patent Office708 DaysField of Search315/287,247 307/232,252UA 340/40US Class Current340/909CPC Class CodesG08G 1/081 Plural intersections under ...
