LED Driver Circuit Clock Synchronization for Light Uniformity
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Solution Overview
Problem
Conventional LED driving methods for larger scale LCDs face challenges with limited light uniformity, low driving efficiency, and high costs, particularly due to non-uniform light intensity caused by AC driving apparatuses using phase and time span differences.
Innovation Solution
A light source driving apparatus that employs a clock synchronization unit, control unit, switch unit, and feedback unit to adjust the pulse width of the driver current based on a clock synchronization signal and feedback signals, ensuring uniform light intensity and efficiency by modulating the AC voltage applied to LED light source modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If AC driving apparatus uses phase and time span differences to drive LEDs, then driving efficiency is improved, but light uniformity deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the microcontroller monitors the actual light output of LEDs and adjusts the pulse width modulation (PWM) signals dynamically. The feedback unit detects the light intensity and feeds this information back to the microcontroller, which then modifies the driving parameters to achieve uniform light distribution across all LEDs while maintaining high driving efficiency through AC power utilization.
Solution Approach 2:
The system dynamically adjusts the pulse width of PWM signals based on real-time feedback from light sensors. The microcontroller continuously modifies the duty cycle and timing parameters of AC-driven LED pulses to compensate for variations in light output, ensuring uniform illumination while maintaining efficient AC power utilization throughout operation.
2Illumination intensity
If DC driving units are used to improve light uniformity and conversion efficiency, then light uniformity and conversion efficiency are improved, but device complexity and cost increase
Solution Approach 1:
The patent changes the fundamental operating parameter from DC to AC power supply, eliminating the need for complex DC-AC converter circuits and associated control hardware. By utilizing AC power directly with PWM modulation, the system achieves comparable or superior light uniformity through software-based control while significantly reducing circuit complexity and component costs.
Solution Approach 2:
The patent replaces the mechanical/electrical DC power conversion system with an AC-based PWM control system. Instead of using complex DC driving circuits with multiple conversion stages, the invention directly modulates AC power to LED strings using microcontroller-based PWM, thereby simplifying the overall driving unit architecture while maintaining or improving light uniformity.
3Productivity
If over-current detectors with preset values are used to adjust current to LEDs, then driving efficiency is improved, but light uniformity deteriorates due to phase and driving time differences
Solution Approach 1:
The patent employs periodic PWM signaling synchronized with the AC power cycle to drive LED strings. By using uniform periodic pulse patterns across all LED strings rather than different time spans, the system maintains consistent current delivery to each LED while preserving AC power efficiency. The periodic action ensures that all LEDs receive equivalent driving conditions over each AC cycle, eliminating the light uniformity problems caused by asymmetric time span driving.
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 improves light uniformity and driving efficiency of LED light source modules, reducing costs and complexity by dynamically adjusting the LED driver current to achieve desired brightness levels, suitable for larger scale LCD applications.
Implementation Method 1
Light emitting diodes (LEDs) are commonly used as visual functionality indicators for electronic devices
Implementation Method 2
When the switch unit determines AC voltage is applied, and the driver current signal is applied from the control unit, current is applied to the LED light source module
Data Source
AI summary
A light source driving apparatus to drive at least one light source module includes a switch unit for coupling in series with an AC power source and the light source module; a clock synchronization unit for coupling to the AC power source and to provide a clock synchronization signal in accordance with an AC voltage of the AC power source; a control unit coupled to receive the clock synchronization signal and to provide to the switch unit an adjusting signal according to a timing of the clock synchronization signal; and a feedback unit coupled to the control unit and to detect a load state of the light source module, the feedback unit configured to provide to the control unit a feedback signal having a value representative of the detected load state of the light source module. The control unit is configured to modulate a pulse width of the adjusting signal according to the feedback signal and a preset brightness value of the light source module, the switch unit responsive to the adjusting signal to open and close to apply the AC voltage to the light source module in accordance with the modulated pulse width.