AC LED Lamp with Selectively Shortable LED Sections
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Solution Overview
Problem
Existing AC LED lamp circuits face inefficiencies due to power loss from current-limiting resistors and reliance on electrolytic capacitors, which lead to reduced reliability and increased heat dissipation, especially under varying line voltages.
Innovation Solution
An AC LED lamp design incorporating a rectifier, an integrated circuit with power switches that selectively short out sections of the LED string, allowing current flow through varying numbers of LEDs to match voltage changes, thereby regulating current and voltage efficiently without electrolytic capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current-limiting resistors are used to control LED current, then current regulation is achieved, but power loss increases and efficiency decreases
Solution Approach 1:
The patent changes the operating parameters by using variable resistance (through capacitor coupling) instead of fixed resistance, allowing the circuit to adapt to voltage variations while maintaining efficient operation. The capacitor value and coupling configuration enable dynamic current control without the continuous power dissipation of resistive elements.
Solution Approach 2:
The patent replaces the mechanical/resistive current control system with an electromagnetic field-based system using capacitive coupling. This substitution eliminates the need for power-dissipating resistors while achieving current regulation through reactive impedance control.
2Stability of the object's composition
If electrolytic capacitors are used in AC LED circuits, then voltage smoothing and stability are improved, but reliability decreases due to capacitor failures
Solution Approach 1:
The patent replaces expensive, failure-prone electrolytic capacitors with simpler, more reliable solid-state switching elements and resistive dividers. These alternative components have longer operational lifetimes and higher reliability while achieving the same voltage stabilization function through different mechanisms.
Solution Approach 2:
The patent extracts and removes electrolytic capacitors from the circuit design, eliminating the reliability issues they cause. The voltage smoothing function is achieved alternatively through RC time constants and switching control without requiring energy-storing capacitive elements.
3Power
If high line voltage is supplied to LED strings, then power output increases, but power loss across resistances increases significantly
Solution Approach 1:
The patent implements dynamic control where the circuit automatically adjusts its operating parameters based on the supplied voltage level. Through voltage detection and switching control, the system optimizes the LED string configuration and current distribution to maximize power output while minimizing resistive losses at any given voltage level.
Solution Approach 2:
The patent divides the LED string into multiple parallel strings with different numbers of LEDs. This segmentation allows selective activation of appropriate string combinations based on input voltage level, enabling efficient power utilization across varying voltage conditions while reducing the burden on current-limiting resistors.
4Adaptability or versatility
If line voltage varies, then adaptability is affected, but using resistors to compensate increases heat dissipation
Solution Approach 1:
The patent incorporates voltage detection and feedback control mechanisms that monitor line voltage variations and automatically adjust circuit operation accordingly. This feedback system enables wide voltage adaptability while maintaining optimal operating conditions and minimizing heat generation through intelligent control rather than passive resistive compensation.
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 achieves high efficiency, reliability, and reduced heat dissipation by dynamically controlling the number of LEDs in the current path, minimizing power loss and extending the lamp's mean time to failure while avoiding high-frequency power switching and electrolytic capacitor failures.
Implementation Method 1
Each power switch is coupled so that it can separately and selectably short out a corresponding one of several groups of LEDs in the LED string
Implementation Method 2
The AC LED lamp receives and is powered by an incoming AC signal such that a rectified version of the signal is present across the LED string
Data Source
AI summary
An LED lamp includes a rectifier, an integrated circuit and a string of series-connected LEDs. The lamp receives an incoming AC signal such that a rectified version of the signal is present across the LED string. The integrated circuit includes a plurality of power switches. Each power switch is coupled so that it can separately and selectably short out a corresponding one of several groups of LEDs in the string. As the voltage across the string increases the integrated circuit controls the power switches such that the number of LEDs through which current flows increases, whereas as the voltage across the string decreases the integrated circuit controls the power switches such that the number of LEDs through which current flows decreases. LED string current flow is controlled and regulated to provide superior efficiency, reliability, anti-flicker, regulation against line voltage variations, power factor correction, and lamp over-voltage, over-current, and over-temperature protection.