Device and method for detecting a short-circuited light-emitting diode in a light device of a motor vehicle
First Claim
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1. A light device for a motor vehicle, said light device comprising;
- driving means for powering a plurality of light-emitting diodes, LEDs, mounted in series, each of said LEDs being characterized by the same forward voltage Vf dependent on its junction temperature;
first means for measuring said junction temperature of said LEDs;
second means for measuring an electrical voltage at the terminals of an assembly; and
processing means for detecting a failure of at least one of said LEDs of said assembly;
wherein said processing means are configured to;
compare said electrical voltage at said terminals of said assembly measured at a first given instant to said electrical voltage at said terminals of said assembly measured at a second given instant, said comparison being conditional on the identity of said junction temperature of said LEDs measured at said first and second instants; and
detect a failure of at least one of said LEDs of said assembly as a function of said comparison.
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Abstract
A light device that makes it possible to detect a short-circuited light-emitting diode in a series assembly of a plurality of such diodes. By taking into account the junction temperature of the diodes, the device and the method associated therewith make it possible to avoid false positive short-circuit detections. The device is also capable of learning the operating parameters necessary to the detection independently and dynamically, which makes it particularly adaptive.
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Citations
20 Claims
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1. A light device for a motor vehicle, said light device comprising;
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driving means for powering a plurality of light-emitting diodes, LEDs, mounted in series, each of said LEDs being characterized by the same forward voltage Vf dependent on its junction temperature; first means for measuring said junction temperature of said LEDs; second means for measuring an electrical voltage at the terminals of an assembly; and processing means for detecting a failure of at least one of said LEDs of said assembly; wherein said processing means are configured to; compare said electrical voltage at said terminals of said assembly measured at a first given instant to said electrical voltage at said terminals of said assembly measured at a second given instant, said comparison being conditional on the identity of said junction temperature of said LEDs measured at said first and second instants; and detect a failure of at least one of said LEDs of said assembly as a function of said comparison. - View Dependent Claims (2, 3, 4, 5, 6, 17, 18, 19, 20)
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7. A method for detecting a short-circuited light-emitting diode, LED, in a light device for a motor vehicle, said light device comprising:
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driving means for powering a plurality of light-emitting diodes, LED, mounted in series, each of said LEDs being characterized by the same forward voltage Vf dependent on its junction temperature; first means for measuring said junction temperature of said LEDs; second means for measuring an electrical voltage at the terminals of an assembly; processing means for detecting a failure of at least one of said LEDs of said assembly, wherein said method comprises the following steps; comparing said electrical voltage at said terminals of said assembly measured at a first given instant to said electrical voltage at said terminals of said assembly measured at a second given instant, said comparison being conditional on the identity of said junction temperature of said LEDs measured at said first and second instants; and detecting a failure of at least one of said LEDs of said assembly as a function of said comparison. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification