Half-Wave Rectification Circuit for LED Light Strings
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Solution Overview
Problem
Conventional LED strings connected to household AC power sources experience shortened lifetimes due to negative voltage application and generate flicker, while using AC to DC converters is expensive.
Innovation Solution
A half-wave rectification and low-pass filter circuit with a resistor, diode, and capacitor is used to provide a nearly constant DC voltage to the LED string, eliminating flicker and extending LED lifespan without the need for expensive converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If LEDs are connected directly to household AC power source, then the circuit is simple and inexpensive, but the LED lifetime is shortened due to negative voltage application and flicker is generated
Solution Approach 1:
The patent segments the AC power source connection into two separate paths: a positive half-wave path through the diode to the LED string, and a negative half-wave path through the capacitor to ground. This segmentation allows the LED to receive only positive voltage pulses, eliminating the harmful negative voltage application while maintaining circuit simplicity.
Solution Approach 2:
The diode acts as an intermediary component that selectively allows only positive half-waves to pass to the LED string while blocking negative half-waves. The capacitor serves as an intermediary that provides a path to ground for the negative half-waves, preventing them from reaching the LED. These intermediary components enable the LED to operate with a simplified circuit while protecting it from harmful voltage conditions.
2Device complexity
If LEDs are connected directly to household AC power source, then the circuit is simple and inexpensive, but 60 Hz flicker is generated because LEDs only work under positive half-waves
Solution Approach 1:
The patent extracts the harmful negative half-wave component from the AC power source by providing a separate capacitor path to ground. This extraction removes the cause of flicker (negative voltage application) while maintaining the simple circuit structure, as the capacitor path is straightforward and does not require complex control circuitry.
3Reliability
If AC to DC converters are used with each LED light string, then flicker is eliminated and LED lifetime is extended, but the cost becomes substantially more expensive
Solution Approach 1:
The patent employs inexpensive, simple components (diode and capacitor) that are much cheaper than full AC to DC converters. These components are designed to be disposable or replaceable, providing sufficient protection for LED operation without requiring expensive, complex converter circuitry. The diode and capacitor are standard, low-cost electronic components that can be easily manufactured and assembled.
4Reliability
If AC to DC converters are used with each LED light string, then flicker is eliminated and LED lifetime is extended, but the device complexity increases
Solution Approach 1:
The patent extracts only the essential function needed for LED protection (blocking negative half-waves) by using simple diode and capacitor components, rather than implementing a complete AC to DC conversion system. This extraction approach maintains reliability while significantly reducing circuit complexity, as only the necessary components are included rather than a full converter architecture.
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 effectively extends the lifetime of LEDs and eliminates flicker by providing a stable DC voltage, using low-cost components and reducing the cost of AC to DC conversion.
Implementation Method 1
a diode connected in series with the resistor
Implementation Method 2
a capacitor connected between an output node of the diode and a second lead of the alternating current power source
Data Source
AI summary
Disclosed is a low cost LED string circuit design that uses an inexpensive half-wave rectification and low-pass filter circuit that is designed to produce minimal flicker in the LED string that is connected to the circuit. The components of the half-wave rectification and low-pass filter circuit are selected in accordance with design principles that prevent glittering and flickering of the LED string. The circuit components of the half-wave rectification and low-pass filter circuit can be embedded in an outlet plug or as a separate independent unit between an AC power plug and the LED string.