Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/20—Controlling the colour of the light
  • H05B45/28—Controlling the colour of the light using temperature feedback
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/10—Controlling the intensity of the light
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/10—Controlling the intensity of the light
  • H05B45/18—Controlling the intensity of the light using temperature feedback
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
  • H05B45/56—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits involving measures to prevent abnormal temperature of the LEDs

Definitions

• the present invention relates, in general, to a headlight of a motor vehicle, and relates, in particular to a headlamp with light-emitting diode for a motor vehicle.
• the invention relates to a method for managing the power of a light-emitting diode headlamp optical module for a motor vehicle.
• a light emitting diode projector generally comprises, on the one hand, one or more optical modules, that is to say a light source, comprising one or more light emitting diodes and a reflector, and, on the other hand, a means of management of the power of the optical module.
• a light-emitting diode is formed by the junction of two semiconductors, one doped "P”, the other doped “N”.
• a temperature at the heart of the LED called junction temperature T, can be determined.
• Each light-emitting diode is further characterized by a maximum junction temperature T max , that is to say a maximum operating temperature admissible by the diode, not to be exceeded so as not to alter it and thus guarantee its duration of life. This temperature is generally specified by the manufacturer.
• a light emitting diode Under electrical excitation, a light emitting diode emits photons and heat which represents, respectively, approximately 20% and 80% of its dissipated power. When in operation, a light emitting diode therefore tends to heat up.
• the power management means applies a nominal current to the optical module so that each light-emitting diode can operate correctly, under normal conditions.
• the temperature of the light-emitting diode headlamps can quickly approach the maximum permissible junction temperature T max , in particular for headlamps located at the front of the vehicle, near the engine.
• Such power management thus makes it possible to optimize the operation of the projector at high ambient temperatures while guaranteeing the integrity of the light-emitting diode.
• the optical module receives a nominal current and the efficiency of each light-emitting diode is below its optimal capacities.
• the present invention relates to a method for managing the power of the optical module of a projector making it possible to adapt and optimize the operation of light-emitting diodes when the ambient temperature is low.
• a method for managing the power of an optical module of a light-emitting diode headlamp for a motor vehicle comprising: the application of a nominal current to the optical module; and reducing the current applied to the optical module when the temperature in the optical module is greater than or equal to a first threshold.
• the current applied to the optical module is increased when the temperature in the optical module is less than or equal to a second threshold, the temperature of the second threshold being less than the temperature of the first threshold.
• the value of the temperature of the first threshold and the value of the temperature of the second threshold are chosen as a function of a maximum admissible junction temperature of the light-emitting diode.
• the temperature of the second threshold can be equal to 0 ° C.
• the current applied to the optical module can be increased by a value equal to or greater than 50% of the nominal current.
• the temperature of the first threshold is equal to 50 ° C.
• the invention also relates to a headlight for a motor vehicle comprising: a light-emitting diode optical module comprising a temperature sensor; and an optical module power management means able to control the value of the current applied to the optical module, said management means being configured to apply a nominal current to the optical module, and configured to reduce the current applied to the optical module when the temperature in the optical module is greater than or equal to a first threshold.
• the management means is configured to increase the current applied to the optical module when the temperature in the optical module is less than or equal to a second threshold, the temperature of the second threshold being less than the temperature of the first threshold.
• the management means is configured to increase the current applied to the optical module when the temperature in the optical module is less than or equal to 0 ° C.
• the management means can be configured to increase the current applied to the optical module by a value equal to or greater than 50% of the nominal current.
• the management means is configured to reduce the current applied to the optical module when the temperature in the optical module is greater than or equal to 50 ° C.
• FIG. 2 illustrates a method of managing the power of an optical module with light emitting diode for a motor vehicle according to the invention, when the temperature in the optical modules is between a first threshold and a second threshold;
• FIG. 3 illustrates a method of managing the power of an optical module with light emitting diode for a motor vehicle according to the invention, when the temperature in the optical modules is greater than or equal to the first threshold;
• FIG. 4 illustrates a method of managing the power of an optical module with light emitting diode for a motor vehicle according to the invention, when the temperature in the optical modules is less than or equal to the second threshold;
• FIG. 5 is a graph illustrating the current and the junction temperature of the light emitting diodes as a function of the ambient temperature.
• a headlamp 1 with light-emitting diode for a motor vehicle comprises at least one optical module 2 with light-emitting diode.
• the optical module 2 can include one or more light-emitting diodes.
• the headlamp 1 with light-emitting diode advantageously comprises three optical modules 2.
• Each optical module 2 comprises a temperature sensor 3 configured to determine the temperature within the optical module with which it is associated.
• the projector 1 also comprises a means for managing the power 4 of the optical modules 2, and therefore light-emitting diodes, capable of controlling the value of the current applied to the optical modules 2.
• the power management means 4 of the optical modules 2 comprises a microcontroller.
• the power management means 4 is configured to apply a nominal current to the optical modules 2.
• the power management means 4 is configured to reduce the current applied to the optical modules 2 when the temperature T in the optical modules 2, determined by the temperature sensor 3, is greater than or equal to a first threshold Ti.
• the power management means 4 is configured to increase the current applied to the optical modules 2 when the temperature T in the optical modules 2 is less than or equal to a second threshold T 2 .
• the temperature of the second threshold T 2 is lower than the temperature of the first threshold Ti.
• the value of the temperature of the first threshold T i and the value of the temperature of the second threshold T 2 are chosen as a function of the maximum admissible junction temperature T max of the light-emitting diode, so that the light-emitting diode does not exceed this maximum junction temperature T max .
• FIGS. 2, 3 and 4 illustrate a method for managing the power of an optical module with a light-emitting diode for a motor vehicle.
• the management method includes the application of a nominal current to the optical modules 2.
• the current applied to the optical modules 2 is reduced.
• the current applied to the optical modules 2 is increased.
• the temperature of the second threshold T 2 is lower than the first threshold Ti.
• the resulting power of the light-emitting diode, and therefore the power dissipated in the form of heat, is less.
• the junction temperature T of the light-emitting diode is then lower than the maximum admissible junction temperature T max and the risk of impairing the operation of the diode is eliminated.
• the junction temperature T of the light-emitting diode is very far from the maximum junction temperature T max admissible by the diode.
• the value of the temperature of the first threshold, the value of the temperature of the second threshold as well as the proportion of increase and the proportion of decrease of the current applied to the optical modules 2, are then chosen as a function of the maximum junction temperature.
• the power of the light-emitting diode is optimized while maintaining a temperature in the optical modules 2 lower than the maximum junction temperature T max admissible by the diode so as not to alter the latter.
• FIG. 5 is a graph representing, in solid lines, the evolution of the current I as a function of the ambient temperature T and, in dotted lines, the evolution of the junction temperature T of the light-emitting diodes as a function of the ambient temperature T.
• the maximum permissible junction temperature T max of the light-emitting diodes of the optical modules 2 is l 50 ° C.
• the headlamp 1 illustrated is configured so that, when the ambient temperature T is greater than Ti, the current I is reduced, and more particularly, the more the ambient temperature T above the first threshold Ti increases, the more the current is increased.
• the current I applied to the optical modules 2 is increased and, advantageously, the lower the ambient temperature T is below the second threshold T 2 , the greater the current applied. Since the more the current I increases, the greater the light flux of the light-emitting diodes, when the ambient temperature T is below the second threshold T 2 , the more the temperature decreases, the greater the light flux of the projector 1 and therefore its great lighting capacity.
• the management means 4 illustrated is advantageously configured to increase the current applied to the optical modules 2 when the temperature T in the optical modules is less than or equal to 0 ° C., ie the second temperature threshold T 2 is equal at 0 ° C.
• the management means is advantageously configured to increase the current applied to the optical modules 2 by a value equal to 50% of the nominal current.
• the management means 4 is preferably configured to reduce the current applied to the optical modules 2 when the temperature in the optical modules 2 is greater than or equal to 50 ° C, ie the first temperature threshold Ti is equal to 50 ° vs.

Landscapes

• Non-Portable Lighting Devices Or Systems Thereof (AREA)
• Lighting Device Outwards From Vehicle And Optical Signal (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=63896314

Family Applications (1)

Country Status (3)

Families Citing this family (4)

Family Cites Families (4)

• 2018
  • 2018-06-29 FR FR1855962A patent/FR3083340B1/fr active Active
• 2019
  • 2019-06-24 EP EP19731769.6A patent/EP3815467A1/de not_active Withdrawn
  • 2019-06-24 WO PCT/EP2019/066714 patent/WO2020002264A1/fr active Application Filing

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