Segmented LED Driver Circuit With Valley-Fill Flicker Control
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Solution Overview
Problem
LED linear power supplies suffer from low efficiency and flickering issues due to current blind areas and inconstant light intensity, particularly in segmented LED loading, and existing solutions like single-stage energy storage capacitors, such as electrolytic capacitors, are large in size and have a low life cycle.
Innovation Solution
A LED driving circuit with an adaptive voltage regulating circuit and LED segment control module that uses a multi-stage valley fill circuit with capacitors and switches to maintain a stable input voltage above the minimum required for LED segments, preventing flickering and ensuring constant light intensity by adjusting the number of active LED segments and current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-stage energy storage capacitor is added to solve current blind area, then the flickering problem is improved, but the circuit size increases and life cycle decreases due to using large electrolytic capacitors
Solution Approach 1:
The patent divides the single-stage energy storage capacitor into multiple smaller capacitors arranged in a bridge circuit configuration. This segmentation allows the system to achieve the required energy storage capacity without using a single large electrolytic capacitor, thereby reducing circuit size while maintaining reliability and eliminating flickering.
Solution Approach 2:
The patent employs a composite capacitor structure combining multiple capacitors (including film capacitors and other types) in a bridge circuit arrangement. This composite approach replaces the traditional single electrolytic capacitor, achieving both compact size and long life cycle while solving the flickering issue.
2Loss of energy
If segmented LED loading is used to improve efficiency, then energy efficiency is improved, but flickering becomes severe due to instant light intensity changes
Solution Approach 1:
The bridge circuit capacitors perform preliminary energy storage and voltage regulation before power is supplied to the segmented LED loading. This preliminary action ensures stable voltage and current supply to each LED segment, preventing instant light intensity changes and flickering while maintaining the efficiency benefits of segmented loading.
Solution Approach 2:
The patent incorporates control circuits that monitor the voltage and current supplied to segmented LED loading and adjust the bridge circuit capacitor discharge accordingly. This feedback mechanism ensures constant light intensity by compensating for any fluctuations, thereby eliminating flickering while preserving energy efficiency.
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 prevents flickering and maintains consistent light intensity while reducing circuit size and extending the life cycle by eliminating the need for large electrolytic capacitors, thus enhancing efficiency and reliability.
Implementation Method 1
a rectifying circuit for converting an alternating current voltage into a direct current voltage
Implementation Method 2
an adaptive voltage regulating circuit for regulating the direct current voltage into an input voltage higher than a lowest voltage used for lighting at least one LED segment
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
In driving a segmented LED loading, an alternating current (AC) voltage is rectified into a direct current (DC) voltage; the DC voltage is regulated into an input voltage and the input voltage is maintained higher than a lowest voltage used for lighting at least one LED segment of the segmented LED loading; the input voltage and a current flowing through the segmented LED loading is detected to generate a switch control signal and a current control signal; respective operation states of each of a plurality of switches of a LED segment switch module are controlled by the switch control signal to control each LED segment of the segmented LED loading as power-supply state or no-power-supply state; and the current of the segmented LED loading is regulated based on the current control signal.