Solid State Lighting Apparatus with Integrated AC Rectifier Circuit
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Solution Overview
Problem
Solid state lighting systems face challenges with the use of ac power, as existing solutions often require costly power converters, reduce efficiency, and result in visible flickering or increased resistive loss due to the need for rectified ac waveforms or increased LED usage in anti-parallel configurations.
Innovation Solution
A solid state lighting apparatus that includes a substrate with a rectifier circuit, current source circuit, and current diversion circuits, allowing direct ac voltage input without an onboard switched mode power supply, using chip-on-board LEDs in series with current diversion and limiter circuits to manage rectified ac voltage and reduce flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power converter is used to convert ac power into dc power for solid state lighting, then the lighting source can operate with stable current, but the cost of the lighting source and overall installation increases
Solution Approach 1:
The patent extracts the power conversion function from a separate onboard power supply and integrates it into the driver circuitry that directly interfaces with AC mains. The driver circuit performs rectification and current regulation functions without requiring a traditional switched-mode power supply, thereby reducing component count and cost while maintaining stable LED current operation
Solution Approach 2:
The driver circuit is designed to perform multiple functions: rectifying AC voltage, regulating current, and protecting against voltage spikes. This multi-functional approach eliminates the need for separate power conversion components, reducing overall system complexity and cost while ensuring reliable LED operation
2Device complexity
If LEDs are driven using a rectified ac waveform, then the lighting source can operate without a power converter, but the LEDs may turn on for only part of the waveform resulting in visible flickering and increased resistive loss
Solution Approach 1:
The driver circuit ensures continuous current flow through the LEDs by implementing full-wave rectification and smoothing capacitance, maintaining LED operation throughout the entire AC cycle rather than allowing intermittent conduction. This eliminates flickering and reduces resistive losses by maintaining steady current flow
Solution Approach 2:
The driver circuit transforms the rectified AC waveform parameters through voltage regulation and current limiting, converting the pulsating DC into a stable current source that maintains constant LED operation. This parameter transformation eliminates the harmful effects of direct rectified AC driving while keeping the system simple
3Device complexity
If LEDs are placed in an anti-parallel configuration to be driven by ac waveform, then the lighting source can operate without a power converter, but twice as many LEDs are required to produce the same luminous flux
Solution Approach 1:
Instead of using anti-parallel LED configurations that require twice as many LEDs, the patent inverts the approach by using a single series string of LEDs with a driver circuit that handles the AC rectification and current regulation. This inversion reduces the LED count by half while maintaining converter-free operation
Solution Approach 2:
The driver circuit acts as an intermediary between the AC mains and the LED string, performing rectification and current regulation functions that would otherwise require complex anti-parallel LED configurations. This intermediary component enables efficient single-string operation without doubling the LED count
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 enables efficient, flicker-free operation with high power factors and lumens per watt efficacy, reducing costs and complexity by eliminating the need for additional power conversion and minimizing LED count.
Implementation Method 1
Typically, a solid state light emitting device generates light through the recombination of electronic carriers, i.e. electrons and holes, in a light emitting layer or region
Implementation Method 2
a rectifier circuit, mounted on a surface of a substrate housed in the solid state lighting apparatus, coupled to an ac voltage source configured to provide a rectified ac voltage to the substrate
Data Source
AI summary
A solid state lighting apparatus can include a substrate having first and second opposing surfaces, where at least one of the opposing surfaces is configured to mount devices thereon. A string of chip-on-board light emitting diode (LED) sets, can be on the first surface of the substrate and coupled in series with one another. An ac voltage source input, from outside the solid state lighting apparatus, can be coupled to the first or second surface of the substrate.