LED Circuit Topology Eliminates Smoothing Capacitor
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Solution Overview
Problem
Existing LED circuit drives are inefficient as they require a smoothing capacitor, which shortens the lifespan of LED lighting devices and cannot drive all LEDs at a predetermined voltage or less, especially when using rectified AC voltage.
Innovation Solution
An LED circuit with a control unit that adjusts the connection of light emitting units in parallel, series, or series/parallel configurations based on input voltage levels, eliminating the need for a smoothing capacitor by using a rectifying unit and strategically placed switches to manage the flow of current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a smoothing capacitor is used in the LED driving circuit, then the circuit can operate with rectified AC voltage, but the lifespan of the LED lighting device is shortened
Solution Approach 1:
The patent removes the smoothing capacitor from the LED driving circuit by using a bridge rectifier to convert AC voltage directly into pulsating DC voltage that can drive LEDs. This extraction of the harmful capacitor component eliminates the lifespan issue while maintaining operation with rectified AC voltage through the bridge rectifier configuration.
Solution Approach 2:
Instead of using a capacitor to smooth the rectified voltage, the patent inverts the approach by using the pulsating nature of rectified voltage directly and controlling LED groups through switching elements. The circuit embraces the pulsating characteristic rather than trying to eliminate it, turning a potential problem into a workable solution.
2Duration of action of stationary object
If only rectified waveform is used to drive LEDs, then smoothing capacitor is eliminated, but not all LEDs can be driven at predetermined voltage or less
Solution Approach 1:
The patent divides the LED array into multiple groups (first LED group, second LED group, third LED group) that can be independently controlled through switching elements. This segmentation allows different subsets of LEDs to be activated based on the input voltage level, enabling full utilization of LEDs across a wide voltage range without requiring a smoothing capacitor.
Solution Approach 2:
The patent employs switching elements that dynamically reconfigure the LED groups based on the instantaneous voltage level of the rectified AC waveform. This dynamic control allows the circuit to adapt to varying voltage conditions in real-time, ensuring optimal LED operation across the entire voltage cycle without needing voltage smoothing.
3Use of energy by moving object
If converter such as flyback converter is used to supply constant current, then LEDs can be driven efficiently, but circuit complexity increases
Solution Approach 1:
The patent extracts and removes the complex flyback converter and smoothing capacitor from the circuit, replacing them with a simpler bridge rectifier and switching element configuration. This extraction maintains energy efficiency by directly controlling LED groups during different portions of the AC cycle while dramatically reducing circuit complexity and component count.
Solution Approach 2:
The patent allows the rectified AC voltage waveform itself to provide the necessary voltage regulation through the strategic switching of LED groups. The circuit uses the inherent characteristics of the rectified waveform rather than requiring an active converter to regulate voltage, achieving energy efficiency through passive, voltage-adaptive switching control.
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 enables efficient driving of LEDs with rectified commercial AC voltage, prolongs the lifespan of the LED circuit, and reduces costs by eliminating the need for a smoothing capacitor, ensuring light emission in most voltage periods.
Implementation Method 1
a circuit for driving the existing light emitting diode mainly uses a scheme in which commercial AC voltage is rectified
Implementation Method 2
A light emitting diode (LED) is a semiconductor device that is configured as a p-n junction structure and emits light by the recombination of electrons and holes
Data Source
AI summary
There is provided an LED circuit. The LED circuit may include 2N+2 light emitting units connected between a 2K−1-th node and a 2K-th node among 4N+4 (N is a natural number) nodes including a first node supplied with input voltage (K is all natural numbers equal to or smaller than 2N+2); 2N+2 switches connected between a 2K-th node and a ground (K is all natural numbers equal to or smaller than 2N+2); 2N+1 switches connected between a 2L−1-th node and a 2L+1-th node and 2N+1 switches connected between a 2L-th node and a 2L+1-th node (L is all natural numbers equal to or smaller than 2N+1); and N switches connected between the first node and a 4M+1-th node (M is all natural numbers equal to or smaller than N).