Light Emitting Diode Failure Detection System for a Vehicle
First Claim
1. A light failure detection system for use in a vehicle having a plurality of light emitting diode lighting devices, said light failure detection system comprising:
- a circuit board;
a plurality of lighting circuits, each lighting circuit being coupled to the circuit board by an input wire;
a plurality of voltage level monitoring circuits on said circuit board, each one of said plurality of voltage level monitoring circuits connected to one of said lighting circuits and adapted to measure the voltage of the one of said light circuits;
a plurality of current monitoring circuits on said circuit board, each one of said plurality of current monitoring circuits connected to one of said lighting circuits and adapted to measure a current draw of the one of said light circuits;
a voltage drop circuit for enabling the plurality of voltage level monitoring circuits and the plurality of current monitoring circuits to measure current and voltage at an adjusted input voltage;
a temperature sensor;
a learn mode switch for placing the light failure detection system into a learn mode wherein said lighting circuits are monitored with the plurality of voltage level monitoring circuits and the plurality of current monitoring circuits to determine threshold voltage and current levels for the lighting circuits;
a microcontroller coupled to the circuit board for storing the threshold voltage and current levels and the temperature sensed by the temperature sensor, said microcontroller being adapted to calculate an adjusted threshold current based on a voltage sensitivity and the sensed temperature; and
a fault indicator for indicating a status of the light failure detection system is a measured current is above or below the adjusted threshold current by a predetermined value.
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Accused Products
Abstract
A light failure detection system for use in a vehicle having a plurality of light emitting diode lighting devices includes a plurality of voltage level monitoring circuits and plurality of current monitoring circuits for measuring the voltage and current draw of a plurality of lighting circuits. A voltage drop circuit enabling the plurality of voltage level monitoring circuits and the plurality of current monitoring circuits to measure current and voltage at an adjusted input voltage is also provided. The system a learn mode for monitoring the lighting circuits with the plurality of voltage level monitoring circuits and the plurality of current monitoring circuits to determine threshold voltage and current levels for the lighting circuits. An adjusted threshold current, based on a voltage sensitivity and a sensed temperature, is calculated and a fault is indicated when a measured current is above or below the adjusted threshold current by a predetermined value.
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Citations
13 Claims
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1. A light failure detection system for use in a vehicle having a plurality of light emitting diode lighting devices, said light failure detection system comprising:
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a circuit board; a plurality of lighting circuits, each lighting circuit being coupled to the circuit board by an input wire; a plurality of voltage level monitoring circuits on said circuit board, each one of said plurality of voltage level monitoring circuits connected to one of said lighting circuits and adapted to measure the voltage of the one of said light circuits; a plurality of current monitoring circuits on said circuit board, each one of said plurality of current monitoring circuits connected to one of said lighting circuits and adapted to measure a current draw of the one of said light circuits; a voltage drop circuit for enabling the plurality of voltage level monitoring circuits and the plurality of current monitoring circuits to measure current and voltage at an adjusted input voltage; a temperature sensor; a learn mode switch for placing the light failure detection system into a learn mode wherein said lighting circuits are monitored with the plurality of voltage level monitoring circuits and the plurality of current monitoring circuits to determine threshold voltage and current levels for the lighting circuits; a microcontroller coupled to the circuit board for storing the threshold voltage and current levels and the temperature sensed by the temperature sensor, said microcontroller being adapted to calculate an adjusted threshold current based on a voltage sensitivity and the sensed temperature; and a fault indicator for indicating a status of the light failure detection system is a measured current is above or below the adjusted threshold current by a predetermined value. - View Dependent Claims (2, 3, 4, 5)
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6. A method of detecting a failure of a light emitting diode lighting device in a vehicle having a failure detection system, said method comprising:
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activating a learn mode; measuring a current (C_ref) and a voltage (V_ref) of a plurality of lighting circuits at an input voltage; measuring a system temperature (T_ref); deactivating said learn mode; measuring at least one light drive input current (C_now) and voltage (V_now) in a normal mode; measuring the system temperature in a normal mode; calculating an adjusted threshold current value based on a voltage sensitivity and system temperature; determining if the measured light drive input current is below or above the adjusted threshold current value by a predetermined value; and displaying an indication of light failure if the measured current is below or above the adjusted threshold current value by said predetermined value. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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Specification