Traffic signal light having ambient light detection

• US 20050030203A1
• Filed: 08/20/2004
• Published: 02/10/2005
• Est. Priority Date: 08/29/2000
• Status: Active Grant

• Current Assignee: Light Vision Systems Incorporated
• Original Assignee: Light Vision Systems Incorporated
• Inventors: Zalta, Michael J., Heald, Arthur D., Sharp, Frank M.
• Granted Patent: US 7,088,261 B2
• Time in Patent Office: Days
• US Class Current: 340/907
• CPC Class Codes: G08G 1/095 Traffic lights
• CPC Class Codes: H05B 45/12 using optical feedback
• CPC Class Codes: H05B 45/325 Pulse-width modulation [PWM]
• CPC Class Codes: H05B 45/58 involving end of life detection of LEDs
• CPC Class Codes: H05B 47/11 by determining the brightness or colour temperature of ambient light
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A traffic signal (310) having a reflector (322, 400) having a plurality of reflective surfaces (330, 402) directing incident ambient light received from the signal lens (318) to a photodetector (322). The reflector is disposed proximate and about a plurality of LEDs (324, 406) which are pulse width modulated by an integrated controller (360) to generate light which is also transmitted through the lens. The photodetector senses the incoming ambient light when the LEDs are in the “off” mode. Incident ambient light is focused by a lens to overfill the reflector and LEDs, and the photodetector is positioned within the redirected incident ambient light from the lens.

Claims

1. A traffic light, comprising:

a lens;

a solid state light source adapted to generate a lightbeam through the lens;

at least one photodetector adapted to receive incident ambient light directed through and focused by the lens; and

a reflector adapted to direct the incident ambient light to the photodetector.

2. The traffic light as specified in claim 1, wherein the reflector has a plurality of angled reflective surfaces.

3. The traffic light as specified in claim 2, wherein the reflective surfaces are substantially parallel to one another.

4. The traffic light as specified in claim 2, wherein the reflector is serrated to define the plurality of reflective surfaces.

5. The traffic light as specified in claim 1, wherein the focused ambient light overfills the reflector.

6. The traffic light as specified in claim 1, wherein the focused ambient light is completely focused on the reflector.

7. The traffic light as specified in claim 1, wherein focused ambient light is reflected by the reflector in 2 directions with respect to a normal of the reflector.

8. The traffic light as specified in claim 1, wherein the traffic light further comprises a housing having a first surface and a second surface, the first surface supporting the reflector and the second surface supporting the photodetector.

9. The traffic light as specified in claim 8, wherein the first surface is a bottom surface, and the second surface is a sidewall.

10. The traffic light as specified in claim 1, wherein the solid state light source is disposed proximate the reflector.

11. The traffic light as specified in claim 10 wherein the reflector encompasses the solid state light source.

12. The traffic light as specified in claim 10, wherein the lens directs the incident ambient light to proximate the light source.

13. The traffic light as specified in claim 1 further comprising an integrated controller selectively controlling the light source, wherein the integrated controller responds to the photodetector when the light source is off.

14. The traffic light as specified in claim 13, wherein the integrated controller adjusts the lightbeam intensity as a function of the photodetector sensing the incident ambient light.

15. The traffic light as specified in claim 13, wherein the integrated controller pulse width modulates (PWM) the light source.

16. A method of operating a traffic light, comprising the steps of:

generating a lightbeam using a solid state light source and a lens transmitting the lightbeam;

focusing and reflecting incident ambient light transmitted through the lens to a photodetector; and

establishing the intensity of the generated lightbeam as a function of the reflected incident ambient light sensed by the photodetector.

17. The method as specified in claim 16 further comprising the step of directing the focused ambient light to proximate the light source.

18. The method as specified in claim 16 further comprising the step of the photodetector sensing the incident ambient light when the solid state light is selectively not generating the lightbeam.

19. The method as specified in claim 16 further comprising the step of using a reflector to direct the incident ambient light to the photodetector.

20. The traffic light as specified in claim 19, wherein the reflector has a plurality of angled reflective surfaces.

21. The traffic light as specified in claim 20, wherein the reflective surfaces are substantially parallel to one another.

22. The traffic light as specified in claim 20, wherein the reflector is serrated to define the plurality of surfaces.

23. The traffic light as specified in claim 19, wherein the focused ambient light overfills the reflector.

24. The traffic light as specified in claim 19, wherein the focused ambient light is completely focused on the reflector.

25. The traffic light as specified in claim 18, wherein focused ambient light is reflected by the reflector in 2 directions with respect to a normal of the reflector.

26. The traffic light as specified in claim 19, wherein the traffic light further comprises a housing having a first surface and a second surface, the first surface supporting the reflector and the second surface supporting the photodetector.

27. The traffic light as specified in claim 26, wherein the first surface is a bottom surface, and the second surface is a sidewall.

28. The traffic light as specified in claim 19, wherein the solid state light source is disposed proximate the reflector.

29. The traffic light as specified in claim 19, wherein the reflector encompasses the solid state light source.

30. The traffic light as specified in claim 19, wherein the lens directs the incident ambient light to proximate the light source.

31. The traffic light as specified in claim 16 further comprising the step of using an integrated controller to selectively control the light source, wherein the integrated controller responds to the photodetector when the light source is off.

32. The traffic light as specified in claim 31, further comprising the step of the integrated controller adjusting the lightbeam intensity as a function of the photodetector sensing the incident ambient light.

33. The traffic light as specified in claim 31, wherein the integrated controller pulse width modulates (PWM) the light source.