CONTROL NETWORK FOR LED-BASED LIGHTING SYSTEM IN A TRANSIT VEHICLE

• US 20090021955A1
• Filed: 09/05/2007
• Published: 01/22/2009
• Est. Priority Date: 07/17/2007
• Status: Active Grant

• Current Assignee: I/O Controls Corporation
• Original Assignee: I/O Controls Corporation
• Inventors: Lin, Jerry, Khor, Chin Seong, Kuang, Baixiong, Wang, Yongchang
• Granted Patent: US 8,400,061 B2
• Time in Patent Office: Days
• US Class Current: 362/479
• CPC Class Codes: B60Q 3/47 Circuits; Control arrangements
• CPC Class Codes: B60Q 3/80 Circuits; Control arrangements for dashboards B60Q3/16; for mass transit vehicles B60Q3/47
• CPC Class Codes: F21V 15/01 Housings, e.g. material or assembling of housing parts F21V15/02 takes precedence housings forming signs or letters G09F13/04
• CPC Class Codes: F21V 17/12 by screwing
• CPC Class Codes: F21V 17/16 by deformation of parts; Snap action mounting
• CPC Class Codes: F21V 3/00 Globes; Bowls; Cover glasses with refracting properties F21V5/00; with reflecting properties F21V7/00; characterised by cooling arrangements F21V29/506
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H05B 45/12 using optical feedback
• CPC Class Codes: H05B 45/18 using temperature feedback
• CPC Class Codes: H05B 45/325 Pulse-width modulation [PWM]
• CPC Class Codes: H05B 45/395 Linear regulators
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices
• CPC Class Codes: H05B 45/56 involving measures to prevent abnormal temperature of the LEDs
• CPC Class Codes: H05B 47/11 by determining the brightness or colour temperature of ambient light
• CPC Class Codes: H05B 47/18 via data-bus transmission
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A transit vehicle lighting system has a plurality of LED-based lighting fixtures for providing interior illumination. A control network comprises a plurality of slave nodes for controlling the LED-based lighting fixtures, and a master node for controlling the slave nodes. The master node may be connected to the slave nodes by a combined power/communication bus in a daisy chain fashion. The slave node may include a power regulator and a controller for providing a target current command to the power regulator, and may adjust the target current based upon temperature measurements or a recorded age of the LEDs. An optical sensor may provide automatic dimming. A reduced number of LEDs may be used in an emergency mode. The lighting fixture may include a ceiling panel fixture and a riser panel attachable by way of a hinge mechanism.

Claims

1. A lighting system for a transit vehicle, comprising:

a plurality of LED-based lighting fixtures, each of said LED-based lighting fixtures comprising a plurality of light-emitting diodes (LEDs) collectively providing area lighting, and a plurality of slave nodes for controlling operation of the LEDs;

a master node for controlling said slave nodes and thereby controlling the operation of said LED-based lighting fixtures;

a power bus interconnecting said master node and slave nodes; and

a communication bus interconnecting said master node and slave nodes.

2. The lighting system of claim 1, wherein said LED-based lighting fixtures comprise an input connector and an output connector, and wherein the power bus comprises power cable segments connecting the LED-based lighting fixtures in a daisy chain.

3. The lighting system of claim 2, wherein said communication bus is integrated with said power cable segments, whereby the communication bus is connected to said LED-based lighting fixtures in a daisy chain.

4. The lighting system of claim 1, wherein said LEDs of an LED-based lighting fixture are groupwise controllable via the slave node.

5. The lighting system of claim 1, wherein said master node responds to a dimming control input by conveying commands over the communication bus to selectively dim LEDs at the LED-based lighting fixtures.

6. The lighting system of claim 5, wherein said dimming control input is provided from a manual dimming control operable by a transit vehicle driver.

7. The lighting system of claim 5, wherein said dimming control input is provided from an emergency lighting command.

8. The lighting system of claim 1, wherein said master node further comprises a voltage regulator for providing low voltage power to digital electronics including a master node micro-controller.

9. The lighting system of claim 1, wherein each of said slave nodes further comprises a voltage regulator for providing low voltage power to digital electronics including a slave node micro-controller.

10. The lighting system of claim 9, wherein said voltage regulator converts power from said power bus for use by the LED-based lighting fixture controlled by the slave node.

11. The lighting system of claim 9, wherein said slave node sets a target LED current level based upon a recorded age of the LEDs, and wherein said voltage regulator adjusts the amount of current supplied to the LEDs of the LED-based lighting fixture according to the target current level.

12. The lighting system of claim 11, wherein voltage regulator adjusts a duty cycle of pulse width modulation in order to adjust the amount of current supplied to the LEDs of the LED-based lighting fixture to the target current level.

13. The lighting system of claim 12, wherein said LEDs are dimmed by reducing the duty cycle of pulse width modulation.

14. The lighting system of claim 11, wherein said LED-based lighting fixture further comprises a temperature sensor, whereby said voltage regulator adjusts the amount of current supplied to the LED-based lighting fixture according to a reading from said temperature sensor.

15. The lighting system of claim 14, wherein the slave node periodically reads an output of said temperature sensor, and commands said voltage regulator to adjust the amount of power supplied to the LED-based lighting fixture in response thereto.

16. The lighting system of claim 1, further comprising an optical sensor for sensing a level of ambient illumination, whereby the LEDs are automatically dimmed if the level of ambient illumination surpasses a dimming command threshold.

17. The lighting system of claim 1, wherein said LEDs are high output.

18. A distributed control network for a transit vehicle lighting system, comprising:

a plurality of LED-based lighting fixtures, each of said LED-based lighting fixtures comprising a plurality of light-emitting diodes (LEDs) for illuminating an area of a transit vehicle;

a plurality of slave nodes for controlling the LED-based lighting fixtures;

a master node in communication with said slave nodes; and

a digital communications bus for communicating among the master node and the slave nodes.

19. The distributed control network of claim 18, further comprising a power bus interconnecting said master node and slave nodes.

20. The distributed control network of claim 19, wherein said power bus is intergrated with the digital communications bus in a plurality of power/data cable segments, and wherein said master node is communicatively coupled to said slave nodes by connecting said slave nodes in a daisy chain using with said power/data cable segments.

21. The distributed control network of claim 18, wherein each of said slave nodes is configured to control an LED current based upon one or both of a recorded age of the LEDs and a measured temperature of at least one of the LEDs.

22. The distributed control network of claim 21, wherein the recorded age of the LEDs is stored in a lifetime counter.

23. The distributed control network of claim 21, wherein the LED current is adjusted by varying a duty cycle of an input power signal across the LEDs.

24. The distributed control network of claim 18, further comprising an optical sensor, whereby said master node operates according to a plurality of brightness modes and automatically commands said slave nodes to dim the LEDs in conditions of brighter ambient illumination.

25. The distributed control network of claim 18, further comprising an emergency lighting mode wherein a reduced number of LEDs are activated by one or more slave nodes.

26. The distributed control network of claim 25, further comprising a battery connected to one of more of said LED-based lighting fixtures to provide energy as a backup power supply.

27. An LED-based lighting fixture for a transit vehicle, comprising:

a plurality of light-emitting diodes (LEDs) for illuminating an area of a transit vehicle;

a power regulator receiving an input power supply signal;

a temperature sensor for measuring a temperature of one or more of said LEDs; and

a controller for providing a target current command to said power regulator, said controller receiving temperature measurements from said temperature sensor and adjusting the target current command in response thereto.

28. The LED-based lighting fixture of claim 27, wherein said controller sets the target current command based at least in part upon a recorded age of the LEDs.

29. The LED-based lighting fixture of claim 27, wherein said power regulator adjusts a duty cycle of pulse width modulation in order to adjust the amount of current supplied to the LEDs to the level indicated by the target current command.

30. The LED-based lighting fixture of claim 29, wherein said LEDs are dimmable by reducing the duty cycle of pulse width modulation.

31. The LED-based lighting fixture of claim 30, further comprising an optical sensor for sensing a level of ambient illumination, whereby the LEDs are automatically dimmed if the level of ambient illumination surpasses a predefined threshold.

32. The LED-based lighting fixture of claim 27, wherein said controller is responsive to commands from a remote master node located in the transit vehicle.

33. The LED-based lighting fixture of claim 32, further comprising a combined power/data bus for communicating between said controller and the master node and for carrying power from a remote on-board power supply to the LED-based lighting fixture in order to provide said input power supply signal.

34. The LED-based lighting fixture of claim 27, further comprising a ceiling panel adapted to abut a transit vehicle interior sidewall, an LED lighting mount on which said LEDs are disposed, and a riser panel adapted to abut a transit vehicle ceiling or interior top mounting surface.

35. The LED-based lighting fixture of claim 34, wherein said riser panel includes a locking mechanism for securing the riser panel to the transit vehicle ceiling or interior top mounting surface, and a detachable hinge for releasably attaching to said LED lighting mount, whereby the riser panel may be fully removed from and reattached in position by releasing said locking mechanism.

36. The LED-based lighting fixture of claim 34, wherein said riser panel includes a locking mechanism for securing the riser panel to the transit vehicle ceiling or interior top mounting surface, and a hinge for attaching the riser panel to said LED lighting mount, whereby the riser panel may be rotationally swung open by releasing said locking mechanism.

37. The LED-based lighting fixture of claim 34, wherein said lighting mount forms a conduit in which said LEDs are disposed.

38. The LED-based lighting fixture of claim 37, wherein said conduit is covered by a contiguous opaque lens which partially diffuses the LED illumination.

39. The LED-based lighting fixture of claim 34, wherein said LEDs are disposed on a front side of said conduit, and further comprising a housing disposed on a back side of said lighting mount for housing control electronics including said power regulator and said controller, and for receiving power and data signals.

40. The LED-based lighting fixture of claim 27, further comprising a battery power supply.

41. The LED-based lighting fixture of claim 27, wherein said controller responds to an emergency lighting mode by causing a reduced number of LEDs to be illuminated.

42. The LED-based lighting fixture of claim 41, wherein said reduced number of LEDs are capable of drawing power from a backup battery power supply when in said emergency lighting mode.

43. An LED-based lighting fixture for a transit vehicle, comprising:

a plurality of light-emitting diodes (LEDs) for illuminating an area of a transit vehicle;

a ceiling panel fixture including a ceiling panel adapted to abut a transit vehicle interior sidewall and an LED lighting mount on which said LEDs are disposed, said LED lighting mount having a plurality of metallic heat dissipating fins for dissipating heat generated by said LEDs; and

a riser panel attached to said ceiling panel fixture and adapted to abut a transit vehicle ceiling or interior top mounting surface;

wherein said riser panel includes a locking mechanism for securing the riser panel to the transit vehicle ceiling or interior top mounting surface.

44. The LED-based lighting fixture of claim 43, further comprising a local voltage regulator for receiving a power supply signal and providing a regulated power output to said LEDs.

45. The LED-based lighting fixture of claim 44, further comprising a controller for adjusting a target current level for said LEDs based upon at least one of a monitored LED temperature and a recorded age of said LEDs.

46. The LED-based lighting fixture of claim 45, wherein said controller adjusts the illumination intensity of said LEDs by adjusting a duty cycle associated with said local power regulator.

47. The LED-based lighting fixture of claim 43, wherein said LED lighting mount comprises an open-ended transverse conduit in which said LEDs are mounted, such that when a second LED-based lighting fixture is adjacently positioned the conduits of each LED-based lighting fixture line up to form a single continuous conduit.

48. The LED-based lighting fixture of claim 43, wherein said riser panel comprises a detachable hinge for releasably attaching to said ceiling panel fixture, whereby the riser panel may be fully removed from and reattached in position by releasing said locking mechanism.