Data Line Driving Circuit for LCD Brightness Uniformity
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Solution Overview
Problem
In large-scale and high-definition liquid crystal display apparatuses, the increased parasitic capacitance and resistance of data lines lead to waveform dullness of driving voltage signals, causing brightness deviations between pixels near and distant from the data line driving circuit.
Innovation Solution
A data line driving circuit is configured with two sections, each generating alternating positive and negative voltage signals, and these sections cyclically drive data lines over a 4-frame cycle, ensuring equal voltage summation across pixels and reducing brightness deviations by averaging charge accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the display panel is scaled up and definition is increased, then the display quality is improved, but the parasitic capacitance and resistance of data lines increase causing waveform dullness and brightness deviation
Solution Approach 1:
The data line driving circuit is divided into multiple independent driving circuits (first data line driving circuit, second data line driving circuit, etc.), each responsible for driving specific data lines. This segmentation allows each driving circuit to be positioned closer to its driven data lines, reducing the impact of parasitic capacitance and resistance on signal waveform, thereby eliminating brightness deviation while maintaining high definition display quality
Solution Approach 2:
Different data lines are driven by different data line driving circuits according to their specific positions and characteristics. Each driving circuit is optimized for its local data lines, compensating for the varying parasitic effects that occur at different locations in large-scale display panels, thus achieving uniform brightness across the entire display area
2Manufacturing precision
If data line driving circuits are provided on upper and lower sides of panel and switched by setting two frames as one cycle, then signal voltages are averaged reducing brightness deviation, but the device complexity increases
Solution Approach 1:
The patent employs periodic switching of data line driving circuits in a cyclic manner. Multiple data line driving circuits are alternately activated in a periodic sequence, with each circuit driving data lines for a specific duration. This periodic operation enables time-averaging of signal voltages, effectively compensating for brightness deviations caused by parasitic effects while managing circuit complexity through systematic time-multiplexed control
Data Source
AI summary
A liquid crystal display apparatus includes a plurality of data lines; a plurality of scan lines which intersect the plurality of data lines; pixels arranged at intersections of the plurality of data lines and the plurality of scanning lines; and a data line driving circuit configured to drive the plurality of data lines, and comprising a first data line driving section and a second data line driving section. 4×n (n: an optional natural number) frames are set as one cycle, and each of the plurality of data lines is circularly driven by one of the first data line driving section and the second data line driving section during one cycle.