LED String Current Diversion for AC Flickering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing solid-state lighting systems driven by rectified AC waveforms often result in visible flickering, lower power factor, and increased resistive loss due to LEDs requiring a minimum forward voltage, and previous solutions like anti-parallel configurations require twice as many LEDs to produce the same luminous flux.
Innovation Solution
A lighting apparatus featuring a string of serially connected LED sets with current diversion circuits that are selectively enabled and disabled responsive to bias state transitions, using transistors and resistors to control current paths and bypass LED sets as the rectified AC voltage varies, eliminating the need for complex comparator circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LEDs are driven using a rectified AC waveform, then the system can operate from AC power sources, but visible flickering occurs because LEDs turn on for only part of the waveform
Solution Approach 1:
The LED string is divided into multiple series-connected LED sets, each with its own current diversion circuit. This segmentation allows different portions of the LED string to be activated at different times during the AC cycle, enabling continuous operation without flickering while maintaining AC power compatibility.
Solution Approach 2:
The patent implements dynamic control of current paths through bias-state-sensitive circuits that automatically adjust which LED sets are active based on the instantaneous voltage level. This dynamic switching eliminates the static on/off behavior that causes flickering, while the circuits remain adaptable to AC power sources.
2Reliability
If LEDs require a minimum forward voltage to turn on, then LED operation is controlled, but power factor decreases and resistive loss increases
Solution Approach 1:
The patent introduces current diversion circuits as intermediary elements between the power source and LED sets. These circuits act as smart switches that redirect current away from LED sets that cannot yet conduct, eliminating the need for resistive voltage division and reducing energy loss while maintaining reliable operation control.
Solution Approach 2:
The system dynamically changes the operational parameters (which LED sets are active) based on the instantaneous voltage level. As voltage increases, different LED sets are sequentially activated, optimizing the use of available power and reducing resistive losses compared to fixed voltage division schemes.
3Duration of action of stationary object
If anti-parallel LED configuration is used to drive LEDs with AC waveform, then continuous operation is achieved, but twice as many LEDs are required to produce the same luminous flux
Solution Approach 1:
Instead of using anti-parallel pairs, the patent segments the LED string into series-connected sets with independent control. This allows all LEDs to contribute to luminous flux during their active periods, eliminating the 50% inefficiency of anti-parallel configurations where only half the LEDs are active at any given time.
Solution Approach 2:
The patent merges multiple LED sets into a single series string with intelligent current diversion, allowing sequential activation of all sets throughout the AC cycle. This combines the advantages of continuous operation with efficient use of all LEDs, reducing the total quantity needed compared to anti-parallel arrangements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively eliminates flickering and reduces resistive loss by incrementally activating and deactivating LED sets in response to voltage changes, maintaining efficient power usage and luminous output with fewer LEDs.
Implementation Method 1
The first one of the current diversion circuits may be configured to conduct current responsive to a forward biasing of the first one of the LED sets
Implementation Method 2
A solid-state light emitting device generates light through the recombination of electronic carriers, i.e. electrons and holes, in a light emitting layer or region
Data Source
AI summary
A lighting apparatus includes a string of light emitting diode (LED) sets coupled in series, each set including at least one LED. The apparatus further includes a plurality of current diversion circuits, respective ones of which are coupled to respective nodes of the string and configured to operate responsive to bias state transitions of respective ones of the LED sets. In some embodiments, a first one of the current diversion circuits is configured to conduct current via a first one of the LED sets and is configured to be turned off responsive to current through a second one of the LED sets. The first one of the current diversion circuits may be configured to conduct current responsive to a forward biasing of the first one of the LED sets and the second one of the current diversion circuit may be configured to conduct current responsive to a forward biasing of a second one of the LED sets.