Matrix Light Source Open-Circuit Fault Detection
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Solution Overview
Problem
Voltage-driven matrix light sources face challenges in diagnosing open-circuit faults with elementary electroluminescent light sources, which is crucial for ensuring compliance with regulatory brightness standards in motor vehicle lighting systems.
Innovation Solution
Integration of an open-circuit fault detection circuit within the integrated circuit of the matrix light source, utilizing a switching device and a load connected in parallel to detect faults by measuring leakage current, allowing for selective connection of elementary light sources to the voltage source based on control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a voltage-driven matrix light source uses a MOSFET transistor with low voltage drop for selective connection, then the switching efficiency is improved, but the ability to diagnose open-circuit faults deteriorates
Solution Approach 1:
A detection circuit is introduced as an intermediary component between the MOSFET transistor and the elementary light source. This detection circuit includes a detection transistor and associated circuitry that can measure the electrical state of the elementary light source when the MOSFET is in the off state, enabling fault detection without requiring the MOSFET to have a measurable voltage drop.
Solution Approach 2:
The detection circuit performs preliminary measurement of the electrical state of the elementary light source before the MOSFET transistor is activated. By checking the electrical state in advance when the MOSFET is off, the system can identify open-circuit faults before attempting to switch the light source, thus enabling diagnosis without relying on voltage drop during switching.
2Use of energy by moving object
If elementary light sources are selectively connected using low voltage drop switching, then the power efficiency is improved, but the diagnostic capability for open-circuit faults worsens
Solution Approach 1:
The detection circuit acts as an intermediary that enables reliable fault diagnosis without compromising the power efficiency of the MOSFET transistor. The detection circuit measures the electrical state through the off-state MOSFET using its inherent leakage current characteristics, allowing fault detection while maintaining the low power consumption of the voltage-driven architecture.
Solution Approach 2:
The patent replaces traditional diagnostic methods that might require mechanical intervention or additional power-consuming components with an electrical measurement approach. The detection circuit uses electrical measurements of leakage current and voltage to diagnose faults, substituting mechanical or invasive diagnostic methods with non-intrusive electrical sensing that maintains system efficiency.
Data Source
AI summary
A matrix light source intended to be supplied with a voltage and having a plurality of electroluminescent semiconductor element-based elementary light sources and a common substrate in contact with an integrated circuit. The integrated circuit includes, for each elementary light source, a switching device for selectively connecting it to a voltage source on the basis of a first control signal. The substrate includes, for at least one of the elementary light sources, an open-circuit fault detection circuit for detecting an open-circuit fault with the elementary light source.