Traffic control system

• US 4,401,969 A
• Filed: 10/08/1981
• Issued: 08/30/1983
• Est. Priority Date: 11/13/1979
• Status: Expired due to Fees

• Current Assignee: Gordon J. Green, Robert J. Debruyn
• Original Assignee: Gordon J. Green, Robert J. Debruyn
• Inventors: Green, Gordon J., deBruyn, Robert J.
• Primary Examiner(s): Groody, James J.
• Application Number:
  US06/309,735
• Time in Patent Office: 691 Days
• Field of Search: 340/32, 340/46, 340/636, 340/35, 340/41 R, 340/40, 340/37, 340/664, 340/638, 340/641, 340/645, 340/642, 340/653, 340/825.69, 340/825.57, 340/825.72, 340/696 , 340/41 A, 455/99, 455/95
• US Class Current: 340/914
• CPC Class Codes: G08G 1/07 Controlling traffic signals
• CPC Class Codes: G08G 1/097 Supervising of traffic control systems, e.g. by giving an alarm if two crossing streets have green light simultaneously

Abstract

In a portable traffic control system in which receivers are controlled from a central transmitter the carrier signal employed is modulated by two different modulation signals in order to command a green light to be shown, reducing the possibility of this happening accidentally. The receipt of a carrier signal with only a single pilot modulation causes production of a red signal. An amber caution light if present is lit automatically upon turning off green, and flashing amber is produced by switching on green and then turning it off before the green can be lit. A drop in battery voltage below a predetermined level will cause a flashing red signal to warn and conserve the battery power. A non-resettable link in circuit with the green light is broken upon existence of a malfunction condition whereby another light is lit while green is alight, so that the green can no longer be lit until the unit is serviced to remove the malfunction.

Claims

1. A traffic control system comprising:

(A) a transmitter unit including;

(1) circuit means for transmitting a carrier signal

(2) circuit means for selectively modulating the carrier signal with a first modulation signal at a first frequency, and

(3) circuit means for selectively modulating the carrier signal with a second modulation signal at a second frequency different from the first frequency, and

(B) a receiver unit for receiving the transmitted carrier signal and any modulation thereof by said first and second modulation signals and adapted to produce in response to receipt of the carrier signal modulated by both modulation signals and in cyclic sequence display of green, amber and red visual traffic signals, the receiver including;

(1) a first detector detecting the said first modulation signal and producing a corresponding first control signal,

(2) a second detector detecting the said second modulation signal and producing a corresponding second control signal, and

(3) receiver circuit means requiring receipt of both said first and second control signals, for longer than a predetermined period and responsive to such receipt to cause display of the green visual traffic signal,

(C) wherein the transmitter includes circuit means for generating a pulse of the said carrier modulated by said first and second modulation signals, which pulse is of a period shorter than the said predetermined period required for the said display of the green visual signal, and

wherein the receiver circuit means is responsive to receipt of both said first and second control signals for a period longer than the said pulse to cause the said display of the green visual signal, is responsive to cessation of receipt of at least one of said control signals to cause display of the amber visual signal, and is responsive to receipt of the said pulse to cause display of the amber visual signal without prior display of the green visual signal.

2. A traffic control system as claimed in claim 1, wherein the said receiver circuit means is responsive to receipt of only either said first or said second modulation signal to cause display of the red visual traffic signal.

3. A traffic control system as claimed in claim 2, wherein said receiver circuit means is operative upon receipt of only said second control signal to cause display of a steady red visual traffic signal, and is operative upon receipt of only said first control signal to cause display of a flashing red visual traffic signal.

4. A traffic control system as claimed in claim 1, wherein the said receiver circuit means includes delay means to which at least one of the first and second control signals are fed to initiate display of the green visual signal, the said delay means delaying the application of the respective signal and thereby delaying display of the green visual signal for a period of time longer than the said pulse.

5. A traffic control system as claimed in claim 1, wherein the receiver circuit means includes a timer initiated in a timing cycle by cessation of said receipt of at least one of the said control signals to control the length of time of display of the amber visual signal.

6. A traffic control system as claimed in claim 1, wherein the receiver circuit means is responsive to cessation of the first control signal to terminate display of the amber visual signal.

7. A traffic control system as claimed in claim 1, wherein the receiver circuit means includes,

a green control circuit portion producing a green enabling signal for display of the green visual signal, and

a red control circuit portion producing a red enabling signal for display of the red visual signal, and

wherein the green enabling signal is fed to the red control circuit portion to prevent the display of the red visual signal, until the green visual signal is no longer displayed.

8. A traffic control system as claimed in claim 1, wherein the receiver circuit means includes,

a green control circuit portion producing a green enabling signal for display of the green visual signal,

an amber control circuit portion producing an amber enabling signal for display of the amber visual signal, and

a red control circuit portion producing a red enabling signal for display of the red visual signal, and

wherein the green and amber enabling signals are fed to the red control circuit portion to prevent display of the red visual signal until the green and amber visual signals are no longer displayed.

9. A traffic control system as claimed in claim 1, wherein the receiver circuit means includes,

a green control circuit portion producing a green enabling signal for display of the green visual signal, and a green off signal as the green visual signal is no longer displayed,

an amber control circuit portion producing an amber enabling signal for display of the amber visual signal, and

a red control circuit portion producing a red enabling signal for display of the red visual signal, and

wherein the green off signal is fed to the red control circuit portion to prevent display of the red visual signal for a period after the green visual signal is no longer displayed and during which period the amber visual signal is displayed in a flashing operation.

10. A traffic control system as claimed in claim 1, wherein the receiver unit includes:

a non-resettable circuit operating member electrically connected in series with the green visual signal for passage therethrough of the current required to display the green visual signal,

circuit means connected to the non-resettable member and responsive to display of the red visual signal while the green visual signal is displayed to apply to the member an additional current sufficient to activate the non-resettable member to open the circuit including the green visual signal so that the green visual signal can no longer be displayed.

11. A traffic control system as claimed in claim 10, wherein said non-resettable member is a fusible link, and said circuit means connected to the member comprise an SCR device having an electrode thereof connected to the fusible link in parallel with the green visual signal, and having its gate electrode supplied with control current while the red visual signal is displayed.

12. A traffic control system as claimed in claim 1, wherein the receiver unit includes,

a non-resettable circuit member electrically connected in series with the green visual signal for passage therethrough of the current required to display the green visual signal,

circuit means connected to the non-resettable member and responsive to cessation of the said first control signal to apply to the member after a predetermined interval an additional current sufficient to actuate the member to open the circuit including the green visual signal if the green visual signal is still displayed so that the green visual signal can no longer be displayed.

13. A traffic control system as claimed in claim 1, wherein said receiver unit includes,

a green control circuit portion causing a green enabling signal for display of the green visual signal,

a red control circuit portion causing a red enabling signal for display of the red visual signal, and

a generator operating at a predetermined frequency to feed a control signal to the red control circuit portion to display the red visual signal and flash it at said predetermined frequency, and to feed an inhibit signal to the green control circuit portion to ensure that the green visual signal is not displayed.

14. A traffic control system as claimed in claim 13, wherein said receiver unit includes circuit means for detecting the voltage of a power supply for the receiver, said circuit means being responsive to reduction of said voltage below a predetermined value to actuate the said generator and flash the red visual signal.

15. A traffic control system comprising:

(A) a transmitter transmitting a control signal for control in a receiver of the display by the receiver in cyclic sequence of green, amber and red visual traffic signals, and

(B) at least one said receiver receiving the said control signal and responsive thereto to cause the said dispaly;

(C) the transmitter including circuit means for generating and transmitting a green form of said control signal adapted to cause display by each said receiver receiving the said green form control signal of said green visual signal, and for generating and transmitting a pulse of said green form of the control signal of period considerably shorter than that required for said cyclic display of the green visual signal;

(D) each said receiver including circuit means responsive to receipt of said green form of the control signal for a period longer than the said pulse to cause the said cyclic display of the green visual signal, responsive to cessation of said green form of the control signal to cause display of the amber visual signal, and responsive to receipt of said pulse to cause display of the amber visual signal without prior display of the green visual signal.

16. A traffic control system as claimed in claim 15, wherein each said receiver circuit means includes delay means to which the said green form of the control signal is fed to initiate display of the green visual signal, the said delay means delaying the display of the green visual signal for a period of time longer than the said pulse.

17. A traffic control system as claimed in claim 15, wherein each said receiver circuit means includes a timer initiated in a timing cycle by cessation of receipt of said green form of the control signal to control the length of time of display of the amber visual signal.

18. A traffic control system as claimed in claim 15, wherein each said receiver circuit means includes,

a green control circuit portion producing a green enabling signal for display of the green visual signal, and

a red control circuit portion producing a red enabling signal for display of the red visual signal, and

wherein the green enabling signal is fed to the red control circuit portion to prevent the dispaly of the red visual signal until the green visual signal is no longer displayed.

19. A traffic control system as claimed in claim 15, wherein each said receiver circuit means includes,

a green control circuit portion producing a green enabling signal for display of the green visual signal,

an amber control circuit portion producing an amber enabling signal for display of the amber visual signal, and

a red control circuit portion producing a red enabling signal for display of the red visual signal, and

wherein the green and amber enabling signals are fed to the red control circuit portion to prevent display of the red visual signal until the green and amber visual signals are no longer displayed.

20. A traffic control system as claimed in claim 15, wherein each said receiver circuit means includes,

a green control circuit portion producing a green enabling signal for display of the green visual signal,

and a green off signal as the green visual signal is no longer displayed, an amber control circuit portion producing an amber enabling signal for display of the amber visual signal, and

a red control circuit portion producing a red enabling signal for display of the red visual signal, and

wherein the green off signal is fed to the red control circuit portion to prevent display of the red visual signal for a period after the green visual signal is no longer displayed and during which period the amber visual signal is displayed in a flashing operation.

21. A traffic control system as claimed in claim 15, wherein each said receiver unit includes,

a non-resettable circuit operating member electrically connected in series with circuit means of the green visual signal for passage therethrough of the current required to display the green visual signal,

circuit means connected to the non-resettable member and responsive to display of the red visual signal while the green visual signal is displayed to apply to the member an additional current sufficient to activate the member to open the circuit means of the green visual signal so that the green visual signal can no longer be displayed.

22. A traffic control system as claimed in claim 15, wherein each said receiver unit includes,

a non-resettable circuit member electrically connected in series with circuit means of the green visual signal for passage therethrough of the current required to display the green visual signal,

circuit means connected to the non-resettable member and responsive to cessation of the green form of the said control signal to apply to the member after a predetermined interval an additional current sufficient to actuate the member to open the circuit means of the green visual signal if the green visual signal is still displayed so that the green visual signal can no longer be displayed.

23. A traffic control system as claimed in claim 15, wherein each said receiver unit includes,

a green control circuit portion causing a green enabling signal for display of the green visual signal,

a red control circuit portion causing a red enabling signal for display of the red visual signal, and

a generator operating at a predetermined frequency to feed a control signal to the red control circuit portion to display the red visual signal and flash it at said predetermined frequency, and to feed an inhibit signal to the green control circuit portion to ensure that the green visual signal is not displayed.

24. A traffic control system as claimed in claim 15, wherein each said receiver unit includes circuit means for detecting the voltage of a power supply for the receiver, said circuit means being responsive to reduction of said voltage below a predetermined value to actuate the said generator and flash the red visual signal.