2-Wire push button station control system for a traffic light controlled intersection

• US 20060028357A1
• Filed: 08/05/2004
• Published: 02/09/2006
• Est. Priority Date: 08/05/2004
• Status: Active Grant

• Current Assignee: Polara Enterprises, LLC
• Original Assignee: Polara Engineering Incorporated
• Inventors: Beckwith, Leslie A., Cruz, Randy V.
• Granted Patent: US 7,145,476 B2
• Time in Patent Office: Days
• US Class Current: 340/944
• CPC Class Codes: G08G 1/07 Controlling traffic signals

Abstract

A 2-wire control system which communicates with a plurality of pole mounted push button stations of the kind that are found at a traffic light controlled intersection via existing pairs of underground wires over which power and data signals are transmitted so as to enable a visually impaired pedestrian to receive both audible and tactile signals regarding the flow of vehicular traffic through the intersection. The 2-wire control system includes a central control unit that is located at a traffic light control cabinet and is connected to a standard traffic signal light controller. The control unit includes a plurality of 2-wire output ports that are connected to respective pairs of the plurality of push button stations. The central control unit also includes a corresponding plurality of on/off controls and data interfaces by which each of the 2-wire output ports thereof is provided with the power and data signals to be transmitted to respective pairs of push button stations depending upon the entry of a pedestrian request and the illumination of a WALK or DON'"'"'T WALK message.

Claims

1. A control system by which accessible signals are provided to pedestrians regarding the status of vehicular traffic at a traffic light controlled intersection, said control system comprising:

at least one push button station located at the traffic light controlled intersection to be crossed by pedestrians, said push button station including a push button head that is depressed by the pedestrians and message generating means by which to provide at least one accessible message to advise a visually impaired pedestrian when vehicular traffic through the intersection has been halted; and

a control unit that is responsive to the depression of the push button head of said push button station to transmit to the push button station both power and digital data signals over a single line by which to power and control the operation of said message generating means.

2. The control system recited in claim 1, wherein said at least one push button station also includes a microcontroller to receive the power and digital data signals from said control unit, said microcontroller providing output signals to control the operation of said message generating means.

3. The control system recited in claim 2, wherein said message generating means of said at least one push button station includes a vibration driver connected to said microcontroller to cause said push button head to vibrate and thereby provide a tactile indication to the visually impaired pedestrian when vehicular traffic through the intersection has been halted.

4. The control system recited in claim 2, wherein said message generating means of said at least one push button station includes a sound chip in which prerecorded messages are stored and from which an audible indication is provided to the visually impaired pedestrian whether to enter the intersection depending upon the flow of vehicular traffic therethrough.

5. The control system recited in claim 1, wherein said message generating means of said at least one push button station also includes:

a microphone connected to the microcontroller and responsive to the ambient noise in the vicinity of the push button station;

a speaker through which the prerecorded messages stored in said sound chip are emitted to pedestrians; and

an attenuation chip connected to the microcontroller and adapted to vary the volume of the prerecorded messages that are stored in said sound chip and emitted by said speaker depending upon the ambient noise detected by said microphone.

6. The central control system recited in claim 1, wherein said control unit includes a 2-wire output port to which a pair of wires is connected from said at least one push button station, said power and digital data signals being transmitted from said control unit to said push button station over a first of said pair of wires, and the second of said pair of wires being connected to ground.

7. The control system recited in claim 6, wherein said control unit includes a power supply, an electronic switch that is closed to connect said power supply to said 2-wire output port to provide power signals to said at least one push button station over the first of said pair of wires connected to said 2-wire output port, and fault detection means by which to cause said electronic switch to open and said power supply to be disconnected from said 2-wire output port in the event said fault detecting means detects a fault condition in the operation of said control unit.

8. The control system recited in claim 7, wherein said fault detection means includes a microcontroller and current and voltage monitoring means connected to said microcontroller and responsive to the output of said power supply, said microcontroller causing said electronic switch to open in the event that the output voltage or current of said power supply exceeds predetermined limits.

9. The control system recited in claim 8, wherein said control unit also includes a data interface including a driver and a transformer connected between said driver and said 2-wire output port, said driver generating said digital data signals through said transformer to said 2-wire output port to be transmitted from said control unit to said at least one push button station over the first of said pair of wires connected to said 2-wire output port.

10. The control system recited in claim 9, wherein the data interface of said control unit also includes a receiver connected to said transformer to monitor the digital data signals generated by said driver, said receiver communicating to said microcontroller an indication of the magnitude of the digital data signals generated by said driver, and said microcontroller controlling the digital data signals generated by said driver to said transformer in response to the indication provided by said receiver.

11. A control system by which accessible signals are provided to pedestrians regarding the status of vehicular traffic at a traffic light controlled intersection, said system comprising:

a source of power;

at least one push button station located at the traffic light controlled intersection to be crossed by pedestrians, said push button station including a push button head that is depressed by the pedestrians and message generating means by which to provide at least one accessible message to advise a pedestrian when vehicular traffic through the intersection has been halted; and

a control unit connected to said source of power to receive an input signal provided thereby, said control unit being responsive to the depression of the push button head of said push button station to control the operation of said message generating means, said control unit including an on/off control and a data interface,

the on/off control of said control unit having means by which to monitor the input signal provided by said source of power, said on/off control connecting said push button station to said source of power to energize said message generating means provided that said input signal is above a predetermined level, and said on/off control disconnecting said push button station from said source of power to disable said message generating means provided that said input signal is below the predetermined level,

the data interface of said control unit providing data signals to said push button station to initiate said message generating means.

12. The control system recited in claim 11, wherein each of the on/off control and the data interface of said control unit is connected to said push button station by way of the same electrical conductor.

13. The control system recited in claim 11, wherein said control unit includes a 2-wire output port, said control system further comprising a pair of wires connected between said 2-wire output port and said push button station, the on/off control and the data interface of said control unit connected from said 2-wire output port to said push button station via a first of said pair of wires, and the second of said pair of wires connected to ground.

14. The control system recited in claim 11, wherein the on/off control of said control unit includes an electronic switch connected between said source of power and said push button station, said control unit including a microcontroller adapted to generate control signals to cause said electronic switch to open and close depending upon the level of the input signal provided by said source of power and monitored by said on/off control.

15. The control system recited in claim 14, wherein the input signal monitoring means of said on/off control includes a current shunting resistor connected in electrical series with said electronic switch and a switch control responsive to the current flowing through said current shunting resistor, said switch control causing said electronic switch to open in the event that the current flowing through said current shunting resistor exceeds a predetermined current.

16. The control system recited in claim 15, wherein the input signal monitoring means of said on/off control also includes a voltage monitor connected to said microcontroller and responsive to the voltage of said input signal, said microprocessor generating one of the control signals for causing said electronic switch to open in the event that the voltage to which said voltage monitor is responsive is below a predetermined voltage.

17. The control system recited in claim 14, wherein the data interface of said control unit includes a driver and a transformer, said driver generating said data signals to be provided to said push button station through said transformer.

18. The control system recited in claim 17, wherein said data interface also includes a receiver connected to said transformer and responsive to the data signals generated by said driver through said transformer, said receiver communicating to said microcontroller an indication of the magnitude of said data signals, and said microcontroller controlling the data signals generated by said driver in response to the indication provided by said receiver.

19. The control system recited in claim 11, wherein said push button station includes a microcontroller coupled to each of said on/off control and said data interface of said control unit by which to power said message generating means and initiate said message generating means a certain time after the depression of said push button head.

20. The control system recited in claim 19, wherein the message generating means of said push button station includes a vibration driver connected to said microcontroller to cause said push button head to vibrate and thereby provide a tactile indication to a pedestrian when vehicular traffic through the intersection has been halted.