Chopper Op Amp Gamma Voltage Supply for Display Band Mura Elimination
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Solution Overview
Problem
Existing data driving systems for displays, such as liquid crystal panels, suffer from 'band mura' due to inherent polarity offsets in operational amplifiers, resulting in distinct luminance or color differences between vertical band regions driven by different modules.
Innovation Solution
The implementation of chopper operational amplifiers in the gamma voltage supply, which periodically switch between positive and negative offsets in space and time, eliminating the polarity offset in driving voltages by alternating the operational states of switches and initial states within the amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional operational amplifiers are used in the gamma voltage supply, then the circuit structure is simple, but polarity offset occurs in the driving voltages causing band mura
Solution Approach 1:
The patent applies dynamics by making the operational amplifier's offset polarity dynamic rather than static. The chopper operational amplifier periodically switches between positive and negative offset polarities at a specific frequency, transforming the amplifier from a static component to a dynamic one. This dynamic switching eliminates the persistent polarity offset that causes band mura, while maintaining the relatively simple circuit structure of conventional amplifiers.
Solution Approach 2:
The patent implements periodic action through the chopper operational amplifier that alternates between two operational states at a predetermined frequency. In the first state, the amplifier produces output with positive polarity offset; in the second state, it produces output with negative polarity offset. This periodic switching of offset polarity prevents the accumulation of luminance error in specific vertical band regions, thereby eliminating band mura while keeping the circuit design straightforward.
2Manufacturing precision
If chopper operational amplifiers are used to eliminate polarity offset, then luminance uniformity is improved, but device complexity increases
Solution Approach 1:
The chopper operational amplifier introduces dynamic element (switching mechanism) that periodically alternates between positive and negative offset states. This dynamic approach eliminates the need for complex calibration circuits or multiple amplifiers, achieving luminance uniformity improvement through a relatively simple switching-based architecture.
Solution Approach 2:
By implementing periodic switching between two operational states at a predetermined frequency, the chopper operational amplifier achieves offset elimination through time-averaging effect. This periodic action approach is more circuit-efficient than static compensation methods, as it uses simple switching elements rather than complex feedback or calibration circuits.
Data Source
AI summary
The present invention relates to a data driving system and method for driving a panel. The data driving system comprises: a gamma voltage supply and a D/A converter. The gamma voltage supply produces a plurality of gamma voltages. The D/A converter receives the gamma voltages, a first pixel value and a second pixel value, and converts the first pixel value and the second pixel value to a corresponding gamma voltage in the gamma voltages. When the D/A converter converts the first pixel value, the gamma voltages have a first polarity offset. When the D/A converter converts the second pixel value, the gamma voltages have a second polarity offset. Because the data driving system of the invention periodically switches the first polarity offset and the second polarity offset of the gamma voltage supply, an offset in the driving voltage is eliminated by the first polarity (positive) offset and the second polarity (negative) offset in space and time. Therefore, there is no band mura in the panel.