Phase-Shift PWM Circuit for Quiet Multi-Channel Backlight Dimming
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing backlight units generate noise and wave noise during dimming control due to the simultaneous or overlapping phase control signals provided to multiple channels.
Innovation Solution
A phase shift circuit comprising a frequency multiplier, a frequency synchronizer, and a PWM module that outputs phase-shifted multi-channel control signals, preventing noise and wave noise by synchronizing and shifting the phase of control signals across channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If control signals with the same phase are provided to multiple channels simultaneously, then the circuit structure is simple, but noise and wave noise are generated during dimming control
Solution Approach 1:
The patent applies periodic action by sequentially activating different channels in alternating phases rather than simultaneously. The control signals are divided into first and second phases where odd channels are activated in the first phase and even channels in the second phase, creating a periodic switching pattern that eliminates overlapping current changes and reduces noise generation during dimming control
Solution Approach 2:
The patent segments the control signals into separate phases for different channel groups. By dividing channels into odd and even groups with distinct activation phases, the control waveform is segmented in time, preventing simultaneous switching of all channels and thereby reducing the harmful noise effects while maintaining overall system functionality
2Object-generated harmful factors
If control signals with different phases are provided to multiple channels sequentially, then noise and wave noise are reduced, but the control signal timing becomes complex
Solution Approach 1:
The patent implements periodic action through alternating phase control where the controller sequentially activates odd channels during first phases and even channels during second phases. This periodic switching pattern creates a regular, predictable timing structure that reduces noise while the phase alternation mechanism manages the timing complexity in a systematic way
Solution Approach 2:
The patent applies preliminary action by pre-organizing channels into odd and even groups with predetermined activation phases. This preliminary structuring of control signals allows the system to automatically manage timing complexity through the established phase alternation pattern, reducing noise without requiring complex real-time decision-making
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 phase shift circuit effectively prevents noise and wave noise during dimming control by synchronizing and shifting the phase of control signals, ensuring reliable and noise-free operation of backlight units.
Implementation Method 1
a frequency multiplier outputting a square wave signal by frequency-multiplying a reference signal
Implementation Method 2
a frequency synchronizer receiving the square wave signal to output a triangle wave signal
Data Source
AI summary
Disclosed is a phase shift circuit. The phase shift circuit comprises a frequency multiplier outputting a square wave signal by frequency-multiplying a reference signal, a frequency synchronizer receiving the square wave signal to output a triangle wave signal, and a PWM nodule receiving the triangle wave signal to output a phase-shifted multi-channel control signal.