Backlight Driving Control via Phase-Shifted PWM Signals
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Solution Overview
Problem
Existing backlight driving systems experience interference from electromagnetic fields and noise due to sharp changes in inductive current, particularly when multiple LED channels are active simultaneously.
Innovation Solution
A method and system that control multiple LED strings with a predetermined phase difference in their pulse-width modulating signals, ensuring they are turned on in a time-sharing manner, thereby reducing sharp current changes and electromagnetic interference. This involves outputting pulse-width modulating signals with specific phase differences across channels, and adjusting the backlight driving voltage based on current sampling data to maintain consistent current levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple LED channels are activated simultaneously to improve backlight illumination coverage, then the illumination area is improved, but electromagnetic field interference and noise increase due to sharp current changes
Solution Approach 1:
The patent applies periodic action by implementing time-division multiplexing control where LED channels are activated in sequential phases rather than simultaneously. Each channel receives pulse-width modulating signals with different phase shifts, creating a periodic activation pattern that reduces current surge and electromagnetic interference while maintaining overall illumination coverage.
Solution Approach 2:
The patent segments the backlight driving system into multiple independently controlled LED channels, each receiving modulating signals with different phase characteristics. This segmentation allows the system to control activation timing of individual channels, preventing simultaneous current surges that cause electromagnetic interference while maintaining comprehensive illumination through coordinated phase distribution.
2Stability of the object's composition
If pulse-width modulating signals are applied to multiple LED channels simultaneously to improve illumination uniformity, then illumination quality is improved, but current variation increases causing electromagnetic noise
Solution Approach 1:
The patent implements periodic action through phase-shifted pulse-width modulating signals applied to different LED channels. Each channel receives signals with specific phase relationships, creating a periodic activation pattern that distributes current demand over time. This approach maintains illumination uniformity through coordinated control while reducing peak current variations that generate electromagnetic noise.
Solution Approach 2:
The patent applies dynamics by implementing dynamic phase shifting of modulating signals across LED channels. The system dynamically adjusts the timing and phase of signal application to each channel, creating a moving pattern of activation that smooths current transitions. This dynamic control maintains uniform illumination while minimizing abrupt current changes that cause electromagnetic interference.
Data Source
AI summary
The present disclosure proposes a method and a system of controlling backlight driving. The method includes receiving an initial-pulse-width modulating signal and outputting a corresponding pulse-width modulating signal according to the initial-pulse-width modulating signal. The pulse-width modulating signal is used to control a corresponding LED string to illuminate. A cycle of each of the pulse-width modulating signals is the same with a predetermined phase difference.