Magnetic Amplifier LED Current Sink Voltage Regulation
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Solution Overview
Problem
Existing power circuits for LED backlighting in LCD devices face inefficiencies due to the need for regulated current sinks and varying voltage drops across LED strings, leading to increased power loss and complexity, especially when providing independent anode voltages to each string.
Innovation Solution
A power circuit utilizing magnetic amplifiers, reset current sources, and control circuits to drive each LED string with equal current and independently regulate voltage, minimizing power loss by measuring voltage drops and adjusting reset control currents supplied to the magnetic amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common anode voltage is provided to all LED strings with linear current sinks, then circuit complexity is reduced, but power loss increases due to voltage drop differences across LED strings
Solution Approach 1:
The patent divides the power supply system into separate segments, providing an independent boost converter for each LED string. This segmentation allows each string to receive a tailored anode voltage that matches its specific voltage drop characteristics, eliminating the power loss caused by voltage mismatches in common anode configurations while maintaining manageable circuit complexity through modular design.
Solution Approach 2:
The patent applies local quality by allowing each LED string to have its own customized anode voltage level determined by its specific voltage drop characteristics. Instead of using a uniform voltage for all strings, each string's power supply is locally optimized to match its requirements, thereby minimizing power loss in the current sink transistors while keeping the overall system complexity acceptable through standardized modular components.
2Loss of energy
If independent anode voltage is provided to each LED string, then power loss is minimized, but circuit complexity and cost increase
Solution Approach 1:
The patent employs universal modular boost converter designs that can be replicated for each LED string. Each converter module performs multiple functions: voltage regulation, current control, and protection. This multi-functionality allows the system to achieve minimized power loss through independent voltage regulation while controlling complexity through standardized, interchangeable modules that simplify design, manufacturing, and maintenance.
Solution Approach 2:
The patent implements dynamic voltage regulation where each LED string's anode voltage is automatically adjusted based on its real-time voltage drop characteristics. The boost converters continuously monitor and adapt their output to match the specific requirements of each LED string, ensuring optimal power efficiency while using standardized dynamic control circuits that prevent exponential growth in system complexity.
3Temperature
If LED strings are connected in series, then voltage requirements are met, but current sharing becomes difficult to control
Solution Approach 1:
The patent segments the LED lighting system into multiple independent parallel strings rather than using a single series connection. Each string is equipped with its own boost converter and control circuitry, allowing independent current regulation. This segmentation enables precise control of current in each string while maintaining the necessary voltage levels, avoiding the current sharing problems inherent in series configurations.
Solution Approach 2:
The patent implements feedback control in each LED string's power supply circuit. The boost converters continuously monitor the current and voltage conditions of their respective LED strings and adjust their output accordingly. This feedback mechanism ensures accurate current control in each string while maintaining system stability, eliminating the need for complex inter-string current balancing that would be required in series configurations.
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 maximizes efficiency by ensuring uniform current through each LED string while minimizing power loss and reducing circuit complexity, as magnetic amplifiers effectively regulate voltage and current, optimizing power delivery.
Implementation Method 1
A magnetic amplifier and control circuit are coupled to the LED string. The magnetic amplifier is configured to pass a power current to the LED string while in a saturated state and delay passage of the power current to the LED string when the magnetic amplifier is in a non-saturated state.
Implementation Method 2
A magnetic amplifier assisted LED constant current sink overhead voltage regulation
Data Source
AI summary
A power circuit includes a plurality of LED strings, each LED string having multiple LEDs connected in series. A plurality of magnetic amplifiers, reset current sources, and a control circuit are used to drive each LED string with equal current and to independently regulate the amount of voltage supplied to each LED to maximize efficiency. One magnetic amplifier, one reset current source, and one current sink are dedicated to each LED string. The control circuit measures the voltage drop across each LED string and determines an amount of reset control current in response to the measured voltage drop. The reset control current is supplied by the reset current source to the magnetic amplifier dedicated to the regulated LED string. The amount of reset control current supplied to the magnetic amplifier dictates the amount of voltage supplied to the LED string.