Headlamp LED lighting apparatus and vehicle headlamp lighting system

• US 8,575,839 B2
• Filed: 09/10/2009
• Issued: 11/05/2013
• Est. Priority Date: 09/10/2009
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Inoue, Yu, Ohsawa, Takashi
• Primary Examiner(s): Hammond, Crystal L
• Application Number:
  US13/381,876
• Publication Number:
  US 20120098430A1
• Time in Patent Office: 1,517 Days
• Field of Search: None
• US Class Current: 315/82
• CPC Class Codes: H05B 45/58 involving end of life detection of LEDs

Abstract

A headlamp LED lighting apparatus, which lights an LED block 2 having a plurality of LEDs connected in series, samples the output voltage of the headlamp LED lighting apparatus, calculates the average voltage during every prescribed interval, and has a storage unit for storing the average voltage during every prescribed interval calculated. A control circuit 8 compares the voltage variation in the average voltage during every prescribed interval read out of the storage unit with a prescribed threshold, and decides an LED failure of the LED block 2 from a result of the comparison.

Claims

1. A headlamp LED lighting apparatus for lighting a headlamp which employs as its light source an LED block having a plurality of LEDs connected in series, the headlamp LED lighting apparatus including a control unit for supplying lighting power to the LED block, the control unit comprising:

an average processing unit for calculating an average voltage during every prescribed interval by sampling an output voltage for lighting the LED block; and

a storage unit for storing the average voltage during every prescribed interval calculated by the average processing unit, wherein

the control unit has a function of making a decision of an LED failure of the LED block in accordance with a result of comparing a prescribed threshold with a voltage variation in the average voltage during every prescribed interval read out of the storage unit.

2. The headlamp LED lighting apparatus according to claim 1, wherein

the average processing unit does not use for calculating the average voltage the output voltage sampled in a prescribed interval immediately after turning on the LED block.

3. The headlamp LED lighting apparatus according to claim 1, wherein

the control unit does not use, when the voltage variation between an immediately preceding average voltage and an immediately following average voltage among the average voltages during the prescribed intervals is greater than a prescribed threshold, these two average voltages for the decision.

4. The headlamp LED lighting apparatus according to claim 1, wherein

the control unit captures a measured value of an ambient temperature of the LEDs, corrects the average voltage to a value corresponding to the ambient temperature at the present point in time in accordance with relations between the lighting voltage of the LEDs and the ambient temperature, and decides an LED failure of the LED block in accordance with a result of comparing a voltage variation between the corrected average voltage and a previous average voltage read out of the storage unit with the prescribed threshold.

5. The headlamp LED lighting apparatus according to claim 1, wherein the control unit:

comprises a nonvolatile storage unit for storing failure information indicating an occurrence of an LED failure; and

decides whether to light the LED block or not in accordance with the failure information readout of the nonvolatile storage unit, when the LED block is switched off because a power supply is turned off and when a lighting manipulation is carried out after the switch-off.

6. The headlamp LED lighting apparatus according to claim 5, wherein

the control unit erases the failure information stored in the nonvolatile storage unit in response to an input signal of a prescribed signal.

7. The headlamp LED lighting apparatus according to claim 1, wherein

the control unit supplies onboard equipment with a signal equivalent to failure information during a prescribed interval immediately after turning on a power supply.

8. The headlamp LED lighting apparatus according to claim 1, wherein

a storage element the storage unit comprises for storing the average voltage and failure information indicating an occurrence of the LED failure is nonvolatile.

9. A headlamp LED lighting apparatus to be mounted on a first side of right and left of a vehicle for lighting a headlamp that employs as its light source an LED block having a plurality of LEDs connected in series, a control unit the headlamp LED lighting apparatus includes comprising:

a communication unit for exchanging information about an LED failure defined in at least claim 1 with a second headlamp LED lighting apparatus mounted on a second side of the vehicle.

10. The headlamp LED lighting apparatus according to claim 9, wherein

the control unit exchanges information about an occurrence of the LED failure with the second headlamp LED lighting apparatus mounted on the vehicle via the communication unit, does not stop, even if an LED failure occurs in both LED blocks of the first and second headlamp LED lighting apparatuses, supplying lighting power to at least one of the LED blocks capable of being lit, and continues lighting the LED block capable of being lit.

11. The headlamp LED lighting apparatus according to claim 9, wherein

when a voltage variation in an average voltage of output voltage of the second headlamp LED lighting apparatus, the voltage variation being received by the first headlamp LED lighting apparatus by exchanging information indicating the output voltage with the second headlamp LED lighting apparatus mounted on the vehicle via the communication unit, is approximately equal to a voltage variation in an average voltage of output voltage to be supplied to the LED block of the first headlamp LED lighting apparatus, the control unit does not use for other control, information that the LED failure occurs in the LED block, even if the control unit decides its LED failure.

12. The headlamp LED lighting apparatus according to claim 9, wherein

the control unit exchanges via the communication unit, information indicating output voltage with the second headlamp LED lighting apparatus mounted on the vehicle, calculates an average voltage during every prescribed interval of the second headlamp LED lighting apparatus, decides an LED failure of the second in accordance with a voltage variation in the average voltage during every prescribed interval calculated, and supplies a result of the decision to the second headlamp LED lighting apparatus by communication;

and wherein

the control unit receives its own LED failure information from the second headlamp LED lighting apparatus, the LED failure information being decided by the second headlamp LED lighting apparatus from a voltage variation in an average voltage of the output voltage of the first headlamp LED lighting apparatus, compares the LED failure information with LED failure information about its own LED block as to which the control unit makes a decision by itself, and makes a final decision that an LED failure occurs in its LED block if the two items of the LED failure information have the same content.

13. A vehicle headlamp lighting system comprising:

the headlamp LED lighting apparatus as defined in claim 9; and

a failure information presentation unit mounted on onboard equipment for showing an occurrence of a failure by receiving failure information from the headlamp LED lighting apparatus.

14. A headlamp LED lighting apparatus including a control unit for lighting a headlamp which employs as its light source an LED block having a plurality of LEDs connected in series, wherein the control unit:

comprises a function of deciding an LED failure of the LED block; and

stops supplying lighting power to the LED block when deciding that the LED failure occurs in the LED block.

15. The headlamp LED lighting apparatus according to claim 14, wherein

the control unit, even if it decides that the LED failure occurs in the LED block, maintains lighting until a switch-off operation of the LED block is carried out owing to turning off of a power supply, and does not supply the lighting power to the LED block even if a lighting manipulation is performed after the switch-off following the switch-off operation.

16. The headlamp LED lighting apparatus according to claim 14, wherein

the control unit captures vehicle-speed information about a vehicle thereof, and does not stop supplying the lighting power to the LED block until the vehicle stops even if it decides that the LED failure occurs in the LED block.