Patent Application
20070103337
The present invention generally relates to traffic control devices and more specifically to backup traffic control devices.
In the aftermath of major storms, traffic control devices often do not operate because of the loss of electric power to the traffic control devices. This causes confusions on the roadway, adding to the dangers during and after a storm. Often, drivers that approach an intersection with a non-functioning traffic control device are unaware of laws that require the driver to stop at the intersection and treat the non-functioning traffic control device as an all-way stop sign. The resulting confusion can lead to traffic accidents.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the specification, there is a need in the art for backup traffic control systems and methods.
The Embodiments of the present invention provide methods and systems for backup traffic control systems and methods and will be understood by reading and studying the following specification.
In one embodiment, a traffic control device is provided. The device comprises a sensing circuit adapted to sense a voltage level of power received from a primary power source and output a low power signal when the voltage level drops below a threshold value; a rechargeable backup power supply adapted to store electrical power; at least one lamp coupled to receive power from the rechargeable backup power supply; at least one switch coupled to switch power between the rechargeable backup power supply and the at least one lamp; and a timer adapted to receive the low power signal and generate a cyclical voltage output based on the low power signal, wherein the at least one switch is adapted to receive the cyclical voltage output and cycle the power between the rechargeable backup power supply and the at least one lamp on and off based on the cyclical voltage output.
In another embodiment, a method for controlling traffic at an intersection of two or more roadways is provided. The method comprises sensing a power received from an external power source; when the power received is lower than a threshold value, periodically cycling power from a backup power source to one or more lamps; illuminating the one or more lamps; and controlling traffic based on the one or more lamps.
In yet another embodiment, a system for controlling traffic at an intersection of two or more roadways. The system comprises means for storing electric power; means for charging the means for storing electric power; means for sensing a power received from an external power source; means for illumination, the means for illumination powered from the means for storing electric power; means for cycling the means for illumination on and off, the means for cycling responsive to the means for sensing.
Embodiments of the present invention can be more easily understood and further advantages and uses thereof more readily apparent, when considered in view of the description of the preferred embodiments and the following figures in which:
In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize features relevant to the present invention. Reference characters denote like elements throughout figures and text.
In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of specific illustrative embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical, mechanical and electrical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense.
Embodiments of the present invention provide systems and methods to notify drivers to stop at intersections where the traffic control device has failed due to a loss of electric power. Embodiments of the present invention provide a backup power source and circuitry to implement a blinking red light in one or more directions of an intersection, upon loss of a primary power supply to the traffic control devices.
In one embodiment, during normal operations (i.e. when power is available from primary power source 105), lamp 122 receives electric power supplied by primary power source 105 and is controlled by traffic controller 130. In one embodiment during normal operations, when lamp 122 is a red lamp, traffic controller 130 additionally controls one or more of a green lamp 133 and a yellow lamp 132 in order to control the flow of traffic. In one embodiment, traffic controller 130 includes all the necessary circuitry, including passing of power from primary power source 105, for the normal operation of lamp 122, green lamp 133 and yellow lamp 132 to control traffic. In one embodiment, traffic controller 130 is one of any number of systems for controlling standard traffic light signals, as would be appreciated by one skilled in the art upon reading this specification.
In one embodiment, sensing circuit 112 monitors the power received by traffic control device 110 from primary power source 105. In one embodiment, when the voltage of electric power supplied by primary power source 105 drops below a predefined threshold, sensing circuit 112 outputs a low power signal to timer 118. In one embodiment, sensing circuit 112 comprises a voltage sensing relay, a voltage comparator, or similar power sensing device. Upon receiving the lower power signal, timer 118 cycles switch 120 periodically on and off, allowing current from battery 117 of rechargeable backup power source 115 to periodically flow to lamp 122. Thus, lamp 122 will appear to drivers as a flashing light. In one embodiment, when lamp 122 is a red lamp, the flashing of lamp 122 notifies drivers approaching the intersection to stop before proceeding. In one embodiment, traffic control device 110 further comprises one or more additional lamps 126 each of which flash on and off as directed by timer 118. In one embodiment, timer 118 further cycles one or more additional switches 124 on and off, allowing current from battery 117 of rechargeable backup power source 115 to periodically flow and illuminate additional lamps 126. In an alternate embodiment, additional lamps 126 receive power from rechargeable backup power source 115 via switch 120.
Although this specification uses the term “lamp” to describe lamp 122 and additional lamps 126, one skilled in the art would readily appreciate that “lamp” is not limited to an incandescent bulb, and encompasses any number of light emitting means now existing or developed in the future. For example, in one embodiment, one or both of lamp 122 and additional lamps 126 comprise one or more of, but not limited to, a neon light and an array of light emitting diodes. In one embodiment, solar panel 114 powers battery charger 115 to maintain the charge of battery 117 while traffic control device 110 operates during a loss of primary power source 105. In one embodiment, during normal operation, (i.e. when power from of primary power source 105 is available), solar panel 114 powers battery charger 115 to maintain a trickle charge to the rechargeable battery in order to assure proper operation during a power outage.
As would be appreciated by one skilled in the art upon reading this specification, there are numerous means to realize timer 118 and switch 120, of which this specification provides just an example.
In operation, in one embodiment, when timing device 310 receives the low power signal from sensing circuit 112, timing device 310 outputs a cyclical voltage signal to gate 354 of transistor 350. In one embodiment, the low power signal comprises a logical high signal from sensing circuit 112. As the voltage at gate 354 rises, transistor 350 turns on and allows current to flow from battery 117 to one or both of lamp 120 and additional lamps 126, allowing them to illuminate. As the voltage at gate 354 falls, transistor 350 turns off and interrupts the current flow from battery 117 to one or both of lamp 120 and additional lamps 126, causing them to darken.
In one embodiment one or both of lamp 120 and additional lamps 126 comprise red lamps allowing traffic control device 110 to stop traffic in two or more directions. For example, in one embodiment, when traffic control device 110 controls traffic at a four-way intersection, lamp 120 comprises a red lamp and additional lamps 126 comprise three red lamps so that, upon a loss of primary power source 105, traffic control device 110 flashes red lamps in all four directions of the intersection. In one embodiment, one or more of lamp 122 and additional lamps 126 comprise at least one yellow lamp. For example, one embodiment, when traffic control device 110 controls traffic at a four-way intersection, upon a loss of primary power source 105, traffic control device 110 flashes two red lamps in to stop traffic flowing on a first roadway before entering the intersection, and flashes two yellow lamps to caution divers approaching the intersection on a second, intersecting roadway.
As would be appreciated by one skilled in the art, the threshold value can be any arbitrary value less than a nominal power level usually provided by the external power source, which would indicate a fault or other instability affecting the supply of power from the external power source. In one embodiment, the threshold value is based on one or both of the voltage and frequency of the power received from the external power source.
With the one or more lamps flashing, the flow of traffic approaching the intersection is controlled (470) by alerting drivers of the need to stop before entering the intersection. In one embodiment, the flashing lamps include at least one red lamp flashing in the direction of traffic on a roadway approaching an intersection to notify drivers to stop before entering the intersection. In one embodiment, the flashing lamps include at least one yellow lamp flashing in the direction of traffic on a roadway approaching an intersection to notify drivers to proceed thought the intersection with caution.
As previously discussed above in this specification, there are a number of ways to cycle power from the backup power source to one or more lamps. In one embodiment, cycling power from the backup power source to one or more lamps further comprises generating a cyclical voltage output with a timer. In one embodiment, the timer may be optionally powered from the backup power source. The method then switches power from the backup power source to one or more lamps on and off based on the cyclical voltage output.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
