Solid State Lighting Flicker Reduction via Passive Resonant Circuit
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Solution Overview
Problem
Existing solid state lighting systems using switch-mode power supplies generate electromagnetic interference (EMI) and switching noise, and direct connection to AC power sources can result in visually and physiologically perceivable flicker, which affects user satisfaction and may lead to regulatory restrictions.
Innovation Solution
A solid state lighting system employing a light source ballast with passive signal conditioning circuitry that includes a passive alternating current conditioner and a resonating circuit to increase the frequency of flicker, making it less perceivable and reducing EMI and switching noise, using a combination of inductors and capacitors to multiply the frequency of the output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a switch-mode power supply is used to convert AC to DC, then power conversion efficiency is improved, but electromagnetic interference and switching noise are generated
Solution Approach 1:
The patent removes the switch-mode power supply component entirely from the system, extracting the harmful EMI and switching noise generation source while maintaining power conversion functionality through alternative means (direct AC connection with frequency multiplication circuitry)
Solution Approach 2:
The patent replaces the electronic switching mechanism (MOSFET-based switch-mode power supply) with a passive frequency multiplication approach using resonant circuits and rectifiers, eliminating the mechanical/electronic switching actions that generate EMI and noise
2Object-generated harmful factors
If solid state light source is connected directly to AC line voltage, then EMI and switching noise are reduced, but visually and physiologically perceivable flicker is generated
Solution Approach 1:
The patent employs periodic rectification and frequency multiplication to transform the AC waveform into a higher frequency periodic signal (e.g., converting 60Hz AC to 360Hz or higher), creating a periodic light output that exceeds the human visual system's flicker fusion threshold
Solution Approach 2:
The patent changes the frequency parameter of the power signal from the original AC frequency (e.g., 60Hz) to a multiplied frequency (e.g., 360Hz or higher) through resonant circuits and rectification, thereby transforming the harmful low-frequency flicker into imperceptible high-frequency operation
3Loss of energy
If flicker frequency is kept at AC line frequency (60Hz or 50Hz), then power consumption is minimized, but health side effects are induced
Solution Approach 1:
The patent uses periodic rectification and resonant frequency multiplication to increase the operating frequency from 60Hz or 50Hz to 360Hz or higher, creating a high-frequency periodic signal that eliminates health side effects while maintaining energy efficiency through passive circuitry
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 effectively reduces the detectability of flicker by humans and minimizes EMI and switching noise, improving user satisfaction and potentially avoiding regulatory restrictions by ensuring the flicker frequency exceeds the threshold that is no longer perceived as unhealthy.
Implementation Method 1
a passive resonating circuit coupled to the passive alternating current, or rectified alternating current, conditioner, to multiply the second frequency of the output signal to a multiplied frequency
Data Source
AI summary
An apparatus and method for reducing the perception of flicker of solid state light sources. An alternating current (AC) signal is passed through an AC conditioning circuit and a passive resonating circuit before being supplied to a string of solid state light sources, such as light emitting diodes.