Pixelated Vehicle Lighting System with Current Sensor Feedback
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Solution Overview
Problem
Existing motor vehicle lighting systems with pixelated light sources controlled by controlled current sources suffer from significant electric power losses, increased reaction time, and higher silicon surface area and cost, while being unstable due to unregulated power delivery and impedance losses in long cable harnesses.
Innovation Solution
A lighting system where each elementary light source is controlled by a dedicated switch, with a voltage-controlled power converter and an electric current sensor measuring the current delivered to the pixelated light source, allowing the controller to regulate power and compensate for temperature variations and impedance losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If controlled current sources are used to control each elementary light emitter, then the pixelated light source can be activated selectively, but significant electric power losses occur in the integrated circuit
Solution Approach 1:
The system separates the control function from the power delivery function. Each elementary light emitter is controlled by a dedicated switch for selective activation, while a single voltage-controlled power converter delivers power to all emitters collectively. This segmentation eliminates the need for multiple controlled current sources, reducing power losses in the integrated circuit while maintaining selective activation capability.
2Measurement precision
If controlled current sources are used for each elementary light emitter, then precise current control is achieved, but the reaction time of the pixelated light-emitting diode increases
Solution Approach 1:
The control architecture is segmented into fast-switching elements (dedicated switches for each emitter) and a slower power delivery component (voltage-controlled power converter). The switches can toggle individual emitters rapidly, while the power converter provides stable voltage supply. This segmentation enables fast response times for pixel activation/deactivation while maintaining adequate current control through the combination of switch timing and voltage regulation.
3Adaptability or versatility
If controlled current sources are integrated into the same integrated circuit, then all elementary emitters can be controlled, but the surface area of silicon necessary increases
Solution Approach 1:
The system segments the control architecture so that only simple switching elements (minimal silicon area) are integrated into the pixelated light-emitting diode circuit, while the complex power conversion functionality is implemented externally. This reduces the silicon surface area required in the integrated circuit while maintaining the ability to control all elementary emitters through the combination of external power converter control and integrated switches.
4Device complexity
If a voltage-controlled power converter is used without current measurement, then power delivery is simplified, but the system becomes unstable due to unregulated power delivery
Solution Approach 1:
An electric current sensor measures the actual current delivered by the voltage-controlled power converter to the pixelated light source. This current measurement is fed back to the controller, which adjusts the power converter's output to maintain stable and regulated power delivery. The feedback loop compensates for variations in LED forward voltage, temperature effects, and impedance changes, ensuring system stability while keeping the overall device complexity manageable.
5Adaptability or versatility
If the pixelated light source is remote from the power converter, then system layout flexibility is improved, but impedance losses in the cable harness increase
Solution Approach 1:
The electric current sensor provides real-time measurement of current delivery to the remote pixelated light source. The controller uses this feedback information to compensate for impedance losses in the cable harness by adjusting the power converter output accordingly. This feedback mechanism enables the system to maintain efficient power delivery even when the light source is remotely located, preserving layout flexibility while minimizing energy losses.
Data Source
AI summary
A lighting system for a motor vehicle with a pixelated light source having a plurality of selectively activatable elementary light sources is described. The activation of each elementary light source being controlled exclusively by a switch assigned to the elementary light source. A power converter designed to supply an electrical power to the pixelated light source and a controller designed to control the voltage supplied by the power converter and to control the switches controlling the activation of the elementary light sources. The lighting system also includes an electrical current sensor designed to measure the electrical current supplied by the power converter to the pixelated light source and to transmit information relating to said measured current to the controller.