LED Headlight Defect Detection via Segmented Test Bus
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Solution Overview
Problem
Existing headlight systems with multiple LEDs arranged in series face challenges in detecting and identifying defective diodes, particularly high-impedance ones, leading to lighting errors and color inaccuracies, due to complex identification processes and accidental detection methods.
Innovation Solution
The solution involves tapping test signals at electrical connections of serially consecutive LEDs, evaluating these signals digitally using an evaluation device with analog/digital converters, and routing them via test signal lines to a common bus line, with feedback barriers to prevent strand interference, allowing for efficient detection and identification of defective diodes with minimal power loss and effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple LEDs are arranged in series strands to achieve desired lighting output, then lighting performance is improved, but detection and identification of defective diodes becomes more complex
Solution Approach 1:
The patent divides the headlight system into multiple electrically independent strands, each with its own controllable power source. This segmentation allows individual testing of each strand by activating only one strand at a time, simplifying the identification of defective LEDs within the larger system while maintaining overall lighting performance.
Solution Approach 2:
The patent implements preliminary testing procedures where test signals are applied to each strand before full operation to detect defective LEDs. By performing detection in advance during manufacturing or installation, the complex identification problem is resolved before the system enters normal operation, avoiding later troubleshooting complexity.
2Area of stationary object
If individual LEDs are closely combined into small groups distributed over area to achieve wash light effect, then lighting distribution is improved, but detection of defective diodes becomes more difficult
Solution Approach 1:
By organizing LEDs into discrete strands with electrical isolation, the patent enables systematic testing of each segment. Even though LEDs are closely combined for area coverage, the electrical segmentation allows test signals to be applied individually to each strand, making defective diodes detectable despite their close physical proximity.
Solution Approach 2:
The patent introduces test signal lines as intermediary pathways that connect to electrical connections between serially consecutive LEDs. These intermediaries provide access points for injecting test signals and measuring responses, enabling detection of defective diodes without disrupting the close physical arrangement needed for wash light effects.
3Measurement precision
If test signals are tapped at electrical connections of serially consecutive LEDs to enable defect detection, then detection capability is improved, but power loss increases
Solution Approach 1:
The patent implements periodic testing where test signals are applied intermittently rather than continuously. During normal operation, LEDs function normally with minimal power loss. At scheduled intervals or during manufacturing testing, test signals are applied to detect defective diodes, achieving high detection precision without continuous energy loss.
Solution Approach 2:
The patent applies test signals only to specific strands or specific electrical connections when needed, rather than applying power continuously to all LEDs. This partial action approach enables precise defect detection at critical measurement points while avoiding excessive power consumption across the entire system.
4Measurement precision
If feedback barriers are inserted into test signal lines to prevent mutual influencing of strands, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent introduces feedback barriers as intermediary components in test signal lines. These barriers act as electrical isolators that prevent test signals from one strand from interfering with measurements on other strands. The added complexity is localized to specific test points rather than the entire system, maintaining overall measurement precision.
Solution Approach 2:
The patent applies feedback barriers only at specific locations where test signal lines intersect or where mutual interference is likely to occur. Rather than making the entire system complex, the solution introduces localized complexity only where measurement precision requires isolation, keeping the rest of the system simple.
Data Source
Figure 1~2
AI summary
The invention relates to a headlight comprising a plurality of light-emitting diodes as light sources. The aim of the invention is to rapidly detect and identify a defective diode between light-emitting diodes connected in series in line sections. Said aim is achieved by tapping test signals at taps, by checking said signals in an analysis device for deviations from target values, or by simply visually identifying a defective diode. In order to reduce the effort for wiring the test signals, several test signal lines leading away from individual taps are advantageously guided to buses via rectifier diodes as feedback preventers and are fed to the analysis device via said buses. During a test cycle, only one line section out of all the line sections having test signals leading to a common bus is activated respectively for obtaining the test signals associated with said line section, and the activation is successively advanced across all line sections.