LED Driver Circuit Reducing Flicker Without Large Capacitors
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Solution Overview
Problem
LED lighting devices experience flicker due to current ripples from AC power supplies, which can cause eye fatigue and limit their application in environments requiring comfortable movement recognition, and existing solutions require large numbers and capacities of electrolytic capacitors, affecting aesthetic quality and increasing failure rates.
Innovation Solution
The LED lighting device incorporates a rectifying unit, light-emitting units with constant-current adjusting units, and a series-type switching unit with transistors to control current flow, reducing flicker without increasing the number or capacity of electrolytic capacitors by adjusting constant currents and using diodes and field-effect transistors to manage charge and discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the number and capacity of electrolytic capacitors are increased to reduce current ripples, then flicker is reduced, but aesthetic quality deteriorates and failure rate increases
Solution Approach 1:
The patent changes the operating parameters of the LED driver circuit by introducing a discharge resistance that activates during specific phases of the AC cycle. This resistance parameter modification allows the circuit to reduce current ripples without requiring additional electrolytic capacitors, thereby reducing flicker while avoiding the reliability issues associated with increased capacitor capacity
Solution Approach 2:
The discharge resistance acts as an intermediary element between the power supply and LED load. It mediates the current flow during specific time intervals, providing a controlled discharge path that reduces ripple current without requiring the large capacitor banks that would otherwise be needed to suppress flicker
2Object-affected harmful factors
If the number and capacity of electrolytic capacitors are increased to reduce current ripples, then flicker is reduced, but aesthetic quality deteriorates
Solution Approach 1:
The patent extracts the flicker suppression function from the traditional capacitor-based approach and implements it through a resistance-based discharge mechanism. By removing the need for large electrolytic capacitors, the design eliminates the aesthetic drawbacks of bulky capacitor components while maintaining flicker reduction effectiveness
3Object-affected harmful factors
If constant current is adjusted in light-emitting units, then current ripples are reduced, but device complexity increases
Solution Approach 1:
The patent segments the AC cycle into different time intervals and applies different circuit configurations to each segment. During specific phases, the discharge resistance is activated while maintaining the constant current through the LED. This temporal segmentation allows ripple reduction without requiring complex continuous control circuits
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 reduces flicker, improves illuminance, and decreases the failure rate of electrolytic capacitors, allowing wider LED lighting adoption in various settings while meeting energy efficiency standards, such as ENERGY STAR certification.
Implementation Method 1
a rectifying unit configured to be supplied with an AC voltage from an AC power supply, configured to rectify the same and configured to output a direct current
Implementation Method 2
the current supplied to the first light-emitting unit is supplied by passing through a first diode and the current supplied to the second light-emitting unit is supplied by passing through a second diode
Implementation Method 3
a series-type switching unit supplied with the remaining part of the direct current, the remaining part of the adjusted first constant current and the adjusted second constant current and configured to control delivery of the remaining part of the direct current, the remaining part of the adjusted first constant current and the adjusted second constant current on the basis of opening and closing of a plurality of transistors built into the series-type switching unit
Implementation Method 4
a first LED array to emit light; and a second LED array to emit light
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention presents an LED lighting device for preventing flickering. The device comprises: a rectification unit receiving an alternating current voltage applied from an alternating current power source and rectifying the same so as to output a direct current; a first light-emitting unit receiving the direct current applied thereto and adjusting a first constant current so as to make a first LED array emit light; a second light-emitting unit receiving the adjusted first constant current applied thereto and adjusting a second constant current so as to make a second LED array emit light; and a serial switching unit receiving the direct current and the adjusted first and second constant currents applied thereto so as to control current transmission according to the opening/closing of a plurality of embedded transistors, wherein the direct current and the first constant current, which are to be applied, are applied by passing through first and second diodes, respectively.