AC-Driven LED Lighting with Dynamic Switching Circuitry
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Solution Overview
Problem
Commercial solid state lighting systems face inefficiencies and increased costs due to the need for power converters to convert AC power to DC for LEDs, leading to visible flickering and reduced power factor, and existing AC-driven solutions require more LEDs to maintain luminous flux.
Innovation Solution
A lighting apparatus with a switching circuit and current control circuit that dynamically adjusts the number of conducting LEDs and their connections in response to varying AC voltage, using a rectifier circuit and shunt switches to bypass LEDs and maintain efficient power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a power converter is used to convert AC power to DC power for LEDs, then the lighting source can be powered by AC power, but the cost and efficiency are reduced
Solution Approach 1:
The patent extracts the power converter from the system by designing LEDs that can be directly driven by AC power without requiring conversion to DC. This eliminates the power converter component and its associated energy losses while maintaining AC power compatibility.
Solution Approach 2:
Instead of converting AC to DC as in conventional systems, the patent inverts the approach by using AC power directly to drive the LEDs through a different circuit configuration, thereby eliminating the need for conversion and improving efficiency.
2Adaptability or versatility
If rectified AC waveform is used to drive LEDs, then AC power can be utilized, but visible flickering occurs due to minimum forward voltage requirement
Solution Approach 1:
The patent segments the LED array into multiple strings with different forward voltage requirements. This allows different segments to be activated at different portions of the AC waveform, ensuring continuous illumination without flickering while maintaining AC power utilization.
Solution Approach 2:
The patent employs dynamic switching circuitry that adapts the LED string configuration in real-time based on the instantaneous AC voltage level. This dynamic adjustment ensures that LEDs are always operated above their forward voltage threshold, eliminating flickering while utilizing AC power.
3Duration of action of stationary object
If LEDs are placed in anti-parallel configuration for AC driving, then continuous operation is achieved, but twice as many LEDs are required for same luminous flux
Solution Approach 1:
The patent segments the LED array into multiple strings connected in series, where each string contains LEDs oriented in the same direction. This segmentation allows continuous operation through switching control while using fewer LEDs compared to anti-parallel configuration, as LEDs are not duplicated for reverse polarity protection.
Solution Approach 2:
The patent makes a single LED string serve multiple functions by using switching circuitry to control current direction and magnitude. The same LED string provides continuous illumination without requiring duplicate LEDs for reverse polarity protection, reducing the total LED count while maintaining continuous operation.
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
The solution reduces flickering, maintains efficient power factor, and allows for the same luminous flux with fewer LEDs, thereby lowering costs and improving system efficiency.
Implementation Method 1
Some attempts at providing solid state lighting sources have involved driving an LED or string or group of LEDs using a rectified AC waveform.
Implementation Method 2
Typically, 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 first substrate including a switching circuit, the switching circuit including a first port, a second port and a current control circuit configured to generate a current at the second port of the current control circuit responsive to a varying voltage at the first port. The apparatus further includes a second substrate mounted on the first substrate and including at least two LEDs electrically coupled to the second port of the current control circuit of the first substrate.