Knowledge-Based LED Driver for Lumen Maintenance

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Solution Overview

Problem

Solid-state light sources experience lumen output depreciation over time, and existing solutions that use optical feedback to maintain constant illumination are costly and prone to accuracy issues due to mechanical location dependencies.

Innovation Solution

A driver apparatus with a controller that uses lumens per amp and volts per amp performance characterizations stored in memory to adjust the drive current based on voltage feedback, eliminating the need for external optical sensing and providing fault and end-of-life adaptation without increasing system size or cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If direct optical feedback using a photosensor is used to detect light output and modify drive current, then constant lumen output can be maintained, but package size increases and system cost increases

Engineering Contradiction:

Improvelumen output stabilityVSAvoidpackage size

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/optical feedback system (photosensor detecting light output) with an electrical measurement system. The controller measures electrical parameters (voltage, current) and uses stored L/A and V/A performance characterizations to determine light output and adjust drive current, eliminating the need for physical photosensors and optical paths.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces electrical measurements (voltage and current) as intermediaries to indirectly determine light output. Instead of directly measuring light with a photosensor, the system measures electrical parameters and uses pre-stored performance characterizations (L/A and V/A tables) to calculate lumen output, serving as an intermediary measurement approach.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If direct optical feedback using a photosensor is used to detect light output, then constant lumen output can be maintained, but system cost increases

Engineering Contradiction:

Improvelumen output stabilityVSAvoidsystem cost

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive optical components (photosensors, optical paths, mechanical assemblies) with electrical measurement circuits and memory-based lookup tables. This substitution dramatically reduces component costs while maintaining the ability to maintain constant lumen output through electrical parameter monitoring and control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses inexpensive electrical measurement components and memory storage (lookup tables) instead of expensive optical sensors. The performance characterizations are stored as data in memory, which is a low-cost, easily replaceable component compared to precision optical sensors and their mechanical assemblies.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If a photosensor is used to detect light output, then constant lumen output can be maintained, but mechanical location of the sensor is critical to avoid stray light and measurement errors

Engineering Contradiction:

Improvelight output measurement accuracyVSAvoidsensor location precision

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent eliminates the mechanical positioning problem by replacing the photosensor with electrical measurements. Since electrical measurements are taken at the driver circuit level rather than optically near the light source, there is no mechanical location precision requirement for sensors, and stray light issues are completely avoided.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses electrical measurements as intermediaries to determine light output without requiring physical proximity to the light source. The voltage and current measurements are taken at the driver circuit, and light output is calculated using stored performance characterizations, eliminating the need for precise mechanical sensor placement near the LED.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8072163B2Knowledge-based driver apparatus for high lumen maintenance and end-of-life adaptation

Publication Date: 2011.12.06 GE LIGHTING SOLUTIONS LLC

AI summary

A knowledge-based driver is provided for powering a solid-state light source with a constant current, including a memory that stores lumens per amp and volts per amp performance characterizations of the light source over time, and a controller that operates in a test mode to estimate the light source degradation based on voltage feedback obtained at a predetermined test current value, and to adjust the drive current in normal operating mode according to the estimated device degradation to implement constant lumens control without external optical feedback components.