Source Driver Chopping Controller Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing source drivers in display devices suffer from noise generation in data lines due to the operation of chopping circuits, which can degrade image quality and affect adjacent components.
Innovation Solution
A source driver is designed with a chopping controller that generates a chopping control signal to periodically change the polarity of the amplifier's offset, incorporating a digital-to-analog converter, gamma voltage generator, and output buffer unit, along with switches and a parasitic capacitor to manage noise by varying the slew rate of the chopping control signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a chopping circuit is used to correct amplifier offset, then image quality is improved, but noise is generated in the data lines
Solution Approach 1:
The chopping circuit periodically switches the polarity of the amplifier offset at a specific frequency (e.g., 1/20 of the frame rate) to move the noise to a frequency range less sensitive to human perception, thereby reducing the perceived noise while maintaining offset correction functionality
Solution Approach 2:
The patent changes the operating parameters of the chopping circuit, specifically the switching frequency and duty cycle of the control signal, to optimize the trade-off between offset correction effectiveness and noise generation, making the noise less perceptible
2Manufacturing precision
If the chopping circuit operates at high frequency to reduce noise perception, then image quality improves, but electromagnetic interference increases
Solution Approach 1:
The chopping circuit uses periodic switching at an optimized frequency that balances noise reduction with minimizing electromagnetic interference, selecting a frequency that is high enough to reduce perceptible noise but low enough to avoid excessive EMI
Solution Approach 2:
The patent introduces control signals and circuit elements that act as intermediaries to manage the chopping operation, allowing precise control over the switching timing and duration to minimize electromagnetic radiation while maintaining the noise reduction benefit
Data Source
AI summary
A source driver includes a gamma voltage generator to generate gamma voltages having mutually different voltage levels, a digital-to-analog converter to generate a data voltage corresponding to a grayscale value using the gamma voltages, an output buffer unit to output the data voltage, and a chopping controller to generate a chopping control signal, and to provide the chopping control signal to the output buffer unit. The output buffer unit includes an amplifier connected to an output terminal of the digital-to-analog converter, and a chopping circuit to periodically change a polarity of an offset of the amplifier in response to the chopping control signal. The chopping controller is to change a slew rate of the chopping control signal.