LED Current Control via Single Converter and Duty Cycle Adjustment
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Solution Overview
Problem
Conventional LED control systems are costly and inefficient when controlling multiple channels, as they require multiple boost or buck converters and current regulators, leading to increased expenses and power wastage due to the need for dedicated circuits for each LED string.
Innovation Solution
Implementing a single boost or buck converter with an average current balance element that uses pulsed control signals and ON-OFF switches to regulate multiple LED channels, reducing the need for multiple regulators and optimizing power consumption by adjusting the duty cycle based on current sense inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple dedicated drive circuits (boost/buck converters and current regulators) are used for each LED string, then precise current regulation and reliability are improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent merges multiple dedicated drive circuits into a single shared boost/buck converter that serves multiple LED strings. The converter output is distributed to multiple strings through current regulator circuits that share common components. This consolidation reduces the total number of converters while maintaining current regulation precision through shared control mechanisms and current sensing.
Solution Approach 2:
The single boost/buck converter is designed to serve multiple LED strings simultaneously, making it a multi-functional component. The converter output can be distributed to various strings, and the current regulator circuits are configured to regulate current across multiple channels using shared reference voltages and control signals, thereby reducing overall system complexity.
2Measurement precision
If multiple dedicated drive circuits are used for each LED string, then current control precision is improved, but power consumption increases due to multiple regulators
Solution Approach 1:
Multiple current regulator circuits are merged into a shared architecture where common components (reference voltages, control signals, sensing mechanisms) serve multiple LED strings. This reduces the total number of active regulatory elements while maintaining precise current control through shared control logic and coordinated regulation across channels.
Solution Approach 2:
The patent implements current recycling mechanisms where excess current or energy from one LED string can be recovered and redirected to other strings. The current regulator circuits are configured to manage current distribution efficiently, allowing current to be redirected or recycled between channels rather than being wasted, thereby reducing overall power consumption while maintaining control precision.
3Device complexity
If resistor biased drive solutions are used, then circuit simplicity is improved, but ability to meet dimming requirements and regulate light output over temperature and lifetime is worsened
Solution Approach 1:
The patent replaces static resistor-biased drive circuits with dynamic current regulator circuits that can actively adjust their operation. These regulators use control signals and feedback mechanisms to dynamically adapt to dimming requirements and compensate for temperature variations and LED aging effects, providing both simplicity and adaptability through active control rather than passive components.
Solution Approach 2:
The current regulator circuits incorporate feedback mechanisms that monitor LED current, temperature, and other parameters to automatically adjust regulation. This feedback enables the system to maintain precise current control across varying conditions (temperature, lifetime, dimming levels) while keeping the overall circuit architecture relatively simple through intelligent control rather than complex passive networks.
Data Source
AI summary
Parallel light emitting diode channels may be controlled using a pulsed control signal input characterized by an input duty cycle and one or more current sense input signals. Each of the one or more current sense input signals is indicative of a current through a corresponding load channel of one or more load channels. One or more pulsed channel current control signals are provided to one or more corresponding dimming controls correspondingly coupled to the one or more load channels. Each of the dimming controls is configured to provide an output signal to a corresponding ON-OFF switch, each of which is coupled in series with a corresponding the load channels. The channel duty cycle of each channel current control signal is adjusted relative to the input duty cycle in response to the current sense input signals.