Fault-Protected Current Source for LED Reliability Testing

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Solution Overview

Problem

Existing current sources for LED reliability testing are inadequate in detecting and responding to faults, leading to incorrect stress levels, potential over-stressing, and secondary failures, which compromises the accuracy of reliability test results.

Innovation Solution

A fault-protected current source with a DC-DC converter, overcurrent detection module, and processor that adjusts output voltage and current levels to prevent damaging spikes, ensuring accurate and safe operation of LEDs during testing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the current source delivers excessive current in response to faults, then the fault protection is strong, but the LEDs are over-stressed and their life is reduced

Engineering Contradiction:

Improvefault protection capabilityVSAvoidLED lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The current source incorporates feedback mechanisms that continuously monitor LED operating conditions and automatically adjust current delivery based on real-time status. When faults are detected, the feedback loop reduces current to safe levels, preventing over-stressing while maintaining protection capability.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The current source dynamically adapts its output characteristics based on fault conditions. Rather than delivering fixed excessive current for protection, the system modulates current levels in real-time, transitioning from normal operating levels to reduced protective levels when faults are detected, thereby protecting both the circuit and extending LED life.

Inventive Principle:

Principle #15Dynamics

2Speed

If the current source responds quickly to faults, then the protection is effective, but current transients can damage the LED

Engineering Contradiction:

Improvefault response speedVSAvoidcurrent transient damage

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The current source implements beforehand cushioning by preparing protective measures before faults occur. The system maintains ready-state protection circuits and pre-configured current limiting mechanisms that activate smoothly upon fault detection, cushioning the transition and preventing damaging transients while ensuring rapid protective response.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If LEDs are arranged in series circuits to minimize current sources, then the system complexity is reduced, but a single fault can affect the entire circuit

Engineering Contradiction:

Improvenumber of current sourcesVSAvoidcircuit fault isolation

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The current source implements functional segmentation by dividing protection and monitoring functions into separate modules within the single current source. This allows the system to maintain series LED configuration for simplicity while enabling independent fault detection and isolation capabilities, so that a single LED fault does not necessarily compromise the entire circuit.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentEP2559323B1Fault protected current source for lighting element testing

Publication Date: 2018.05.23 VEKTREX ELECTRONICS SYST

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AI summary

A fault protected current source is provided that can be used to safely drive LEDs in reliability test systems. The current source is includes circuits and processes that detect the common faults found in LED reliability test systems. After a fault is detected, the current source shuts down drive before destructive spikes are produced. Because only true LED failures are counted, this fault protected current source can be used to construct reliability test systems that produce more accurate reliability test data.