Variable Voltage Boost Current Sources for LED Panels
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Solution Overview
Problem
Solid state lighting panels, particularly those used in large-scale applications, face challenges in providing a high color rendering index and uniform lighting due to limited spectral energy, leading to unnatural color representation and potential overheating issues from heat generation.
Innovation Solution
A lighting system with a string of solid state lighting devices and a current supply circuit configured for continuous conduction mode, utilizing a variable voltage boost current supply circuit with a charging inductor, output capacitor, and digital control system for pulse width modulation, ensuring efficient power conversion and independent current control for red, green, and blue LED strings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple solid state lighting devices are connected in series to increase voltage output, then the lighting panel can achieve high color rendering index and uniform light output, but the heat generation increases leading to overheating issues
Solution Approach 1:
The lighting panel is divided into multiple independent LED strings (red, green, blue) that can be controlled separately. Each string is driven by its own current supply circuit, allowing the total light output to be achieved through parallel combination of multiple lower-power strings rather than forcing a single high-power configuration, thereby distributing heat generation across multiple segments
Solution Approach 2:
The patent implements dynamic control of LED strings through pulse width modulation (PWM) and adjustable current sources. The brightness and color temperature can be dynamically adjusted by varying the drive current to each LED string, allowing the system to optimize between color rendering quality and heat generation based on operational requirements
2Illumination intensity
If a high voltage current supply circuit is used to drive multiple LED strings in series, then uniform light output is achieved, but the circuit complexity and power loss increase
Solution Approach 1:
Instead of using a single high-voltage current supply for all LEDs, the patent segments the power supply into multiple independent current sources, each dedicated to a specific LED string. This segmentation allows each current source to operate at optimized voltage and current levels, reducing power loss from high-voltage transmission while maintaining uniform light output through independent control of each string
Solution Approach 2:
The patent employs variable voltage boost current sources that can dynamically adjust their output parameters (voltage, current) based on the specific requirements of each LED string. This parameter adjustment capability allows the system to achieve uniform light output without the excessive power losses associated with fixed high-voltage supply circuits
3Illumination intensity
If independent current control circuits are provided for each LED string to achieve high color rendering index, then color accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent employs a controller that serves multiple functions: it generates PWM signals for dimming control, regulates the variable voltage boost current sources for each LED string, and manages the overall lighting logic. This multi-functional controller reduces the need for separate dedicated circuits for each function, thereby managing device complexity while maintaining independent current control capability for high color rendering index
4Loss of energy
If efficient power conversion is implemented to reduce heat dissipation, then energy efficiency is improved, but the manufacturing cost and device complexity increase
Solution Approach 1:
The patent uses variable voltage boost current sources that can adapt their operating parameters to match the specific requirements of different LED strings and operating conditions. This parameter adaptability enables highly efficient power conversion by operating each current source in its optimal efficiency range, reducing overall heat dissipation while using standardized components that balance manufacturing cost and performance
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 achieves high color rendering index and uniform lighting by efficiently converting at least 85% of input power into output power, reducing heat dissipation and enabling smaller, lighter, and more cost-effective lighting systems with improved thermal performance.
Implementation Method 1
a charging inductor coupled to the voltage input terminal
Implementation Method 2
an output capacitor coupled to the first output terminal
Implementation Method 3
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
Data Source
AI summary
A lighting system includes a lighting panel having a string of solid state lighting devices and a current supply circuit having a voltage input terminal, a control input terminal, and first and second output terminals coupled to the string of solid state lighting devices. The current supply circuit is configured to supply an on-state drive current to the string of solid state lighting devices in response to a control signal. The current supply circuit includes a charging inductor coupled to the voltage input terminal and an output capacitor coupled to the first output terminal. The current supply circuit is configured to operate in continuous conduction mode in which current continuously flows through the charging inductor while the on-state drive current is supplied to the string of solid state light emitting devices.