Source Output Enable Signal Generator for LCD Charge Uniformity
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Solution Overview
Problem
Liquid crystal display panels with shared data lines experience non-uniform charge characteristics due to differences in voltage charging between odd and even columns, leading to vertical stripe artifacts on the display.
Innovation Solution
A liquid crystal display device with a source output enable signal generator that alternately generates delayed source output enable signals to control the timing of data voltage supply to liquid crystal cells, ensuring that odd and even columns charge data voltages of different or same polarity during specific periods, thereby compensating for polarity-based pre-charging time differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single data line is shared between adjacent liquid crystal cells to reduce the number of data lines, then the number of data lines is reduced by half, but non-uniform charge characteristics occur between odd and even columns causing vertical stripe artifacts
Solution Approach 1:
The patent applies preliminary action by pre-charging liquid crystal cells before displaying actual image data. Specifically, during vertical blanking periods, the system alternately pre-charges odd and even column cells with opposite polarity voltages through the shared data lines. This preliminary charging compensates for the inherent non-uniform charge characteristics, ensuring that when actual image data is displayed, both odd and even columns achieve uniform charge levels despite sharing the same data lines.
Solution Approach 2:
The patent implements periodic action by alternating the pre-charging operation between odd and even columns in successive vertical blanking periods. In one vertical blanking period, odd columns are pre-charged with positive polarity while even columns are pre-charged with negative polarity. In the next vertical blanking period, the polarity assignment is reversed. This periodic alternation ensures that both column types experience equivalent charge conditions over time, eliminating vertical stripe artifacts while maintaining the shared data line structure.
2Device complexity
If data voltages are supplied simultaneously to all liquid crystal cells during the same time period, then the driving circuit is simplified, but polarity-based pre-charging time differences cause non-uniform charge characteristics
Solution Approach 1:
The patent applies segmentation by dividing the liquid crystal display into odd and even column groups, and further dividing the vertical blanking period into separate time slots for each group. Instead of treating all cells uniformly, the system segments the pre-charging operation so that odd columns receive pre-charge voltages during one time slot while even columns receive pre-charge voltages during another time slot. This segmented approach allows the system to address the different charge characteristics of odd and even columns independently, achieving uniform charge distribution without requiring complex per-cell control circuits.
Data Source
AI summary
A liquid crystal display and a driving method for preventing a phenomenon causing a non-uniform charge characteristic between liquid crystal cells are disclosed. The liquid crystal display includes a picture display part having a plurality of gate lines and a plurality of data lines and having liquid crystal cells sharing a data line. A gate driver sequentially supplies a scanning pulse to the gate lines. A source output enable signal generator alternately generates a first source output enable signal having a first horizontal period and a second source output enable signal delayed from the first source output enable signal by a time longer than a half of the first horizontal period and shorter than the first horizontal period. A data driver supplies data voltages to the data lines in response to the first and second source output enable signals.