LED Drive Circuit Loop-Back Compensation for Flicker Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional LED lighting devices using sequential driving type AC circuits suffer from severe flicker due to non-luminous intervals, leading to uneven light output and user discomfort, and existing DC driving methods are inefficient with high manufacturing costs and reduced lifespan.

Innovation Solution

An LED drive circuit with a loop-back compensation unit that supplies a second drive voltage during non-luminous intervals, controlling LED drive current based on the number of LEDs turned on in each operation interval to maintain constant light output and improve flicker performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If AC driving is used to eliminate power converters, then manufacturing cost is reduced and lifespan is extended, but flicker performance deteriorates due to non-luminous intervals

Engineering Contradiction:

Improvemanufacturing costVSAvoidflicker

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The capacitor is charged in advance during the non-luminous interval before the LED group needs to emit light. This preliminary energy storage ensures that when the switching element turns on, the capacitor can immediately supply current to the LED group, eliminating the non-luminous interval and preventing flicker while maintaining AC driving benefits

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The capacitor acts as an intermediary energy storage element between the rectified voltage source and the LED group. It bridges the gap during voltage transitions, providing continuous current supply to the LED group and eliminating flicker caused by non-luminous intervals in AC driving

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If sequential driving is used to control LED groups, then power factor is improved, but light output uniformity deteriorates due to non-luminous intervals

Engineering Contradiction:

Improvepower factorVSAvoidlight output uniformity

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The capacitor is charged in advance during intervals when the LED group is not actively driven, ensuring energy is ready before the next luminous interval begins. This eliminates gaps in light output and maintains uniformity while preserving sequential driving's power factor benefits

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The capacitor ensures continuous light emission from the LED group by providing current during transition intervals between sequential driving stages. This eliminates non-luminous intervals and maintains continuous useful light output while preserving the power factor improvements from sequential driving

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS10321529B2LED drive circuit with improved flicker performance, and LED lighting device comprising same

Publication Date: 2019.06.11 SEOUL SEMICONDUCTOR

AI summary

An alternating current sequential drive type LED lighting device having improved flicker performance and being capable of reducing the light output deviation of the LED lighting device generated during operation intervals by removing nonluminous intervals of the LED lighting device by means of a loop-back compensation unit.