Ripple Removing Circuit for LED Control via Regulation Tube
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Solution Overview
Problem
Existing LED driving circuits with power factor correction functions suffer from significant output ripples, which are costly to filter and have low response speed, leading to eye strain and inefficient ripple removal.
Innovation Solution
A ripple removing circuit structure comprising a regulation tube, a capacitor, a current source, and a current generating circuit that converts input current ripples into voltage ripples, allowing for rapid response and effective ripple elimination by regulating the current flowing through the LED load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If large electrolytic capacitors are adopted to filter sine ripples, then ripple filtering capability is improved, but cost increases and circuit integration becomes difficult
Solution Approach 1:
The patent introduces a ripple removing circuit as an intermediary component between the LED driving circuit and the LED load. This circuit includes a regulation tube, capacitor, current source, and current generating circuit that work together to eliminate ripples without requiring large electrolytic capacitors in the traditional filtering position, thus improving ripple filtering capability while maintaining circuit integration
Solution Approach 2:
The patent replaces the traditional mechanical/electrical filtering approach using large capacitors with an active control system that uses a regulation tube and current generating circuit. This substitution transforms the passive filtering mechanism into an active ripple removal process, achieving better filtering results with smaller components and improved integration
2Device complexity
If fixed current charge-discharge mode is used for filter capacitor, then circuit simplicity is improved, but response speed decreases and ripple proportion increases when average current is small
Solution Approach 1:
The patent implements a dynamic current generating circuit that adjusts its output current based on the voltage difference between the input end (connected to the first end of the regulation tube) and output end (connected to the first capacitor). This dynamic adjustment allows the circuit to respond rapidly to changing conditions and adapt to different average current levels, solving the response speed and ripple proportion problems of fixed current modes
Solution Approach 2:
The current generating circuit operates with feedback control, where the current output is regulated according to the voltage difference across the regulation tube. This feedback mechanism enables the circuit to automatically adjust its behavior based on real-time conditions, improving response speed and maintaining low ripple proportions across varying operating conditions
Data Source
AI summary
A ripple removing circuit and an LED control circuit applying the same are described herein. The LED control circuit receives alternating current input, converts the input into direct current with ripples and supplies power for an LED load. The direct current with ripples is connected to a positive end of the LED load, a negative end of the load is connected to a first end of a regulation tube, and a second end of the regulation tube is grounded. A first capacitor is connected between a control end of the regulation tube and the ground, and the time constant of the filter circuit formed by the first capacitor, a current generating circuit and a current source is far greater than a power frequency period. The current flowing across the regulation tube is approximately a direct current free of ripples, thereby decreasing the current ripples going across the LED load.