LCD Panel Drive Stabilizing VCOM Fluctuations
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Solution Overview
Problem
The compatibility issues between time division driving and dot inversion driving schemes in LCD devices, particularly when the number of data lines is even, lead to fluctuations in the common potential VCOM, affecting image quality and flexibility in LCD design.
Innovation Solution
A method that involves time-divisionally selecting data lines from even-numbered data line sets with opposite polarities to stabilize the common electrode potential, ensuring that data signals written into pixels have opposite polarities between different data line sets, thereby reducing fluctuations in the common potential VCOM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If time division driving is implemented with an even number of data lines, then the number of output amplifiers is reduced, but the common potential VCOM fluctuates causing image quality degradation
Solution Approach 1:
The data lines are divided into two separate sets: odd-numbered data lines (D1, D3, D5, D7) and even-numbered data lines (D2, D4, D6, D8). Each set is driven independently with opposite polarities, allowing the system to maintain VCOM stability while using time division driving with an even number of total data lines. This segmentation resolves the contradiction by enabling reduced amplifier usage while preventing common potential fluctuations.
Solution Approach 2:
The patent applies inversion driving by alternating the polarity of data signals between odd and even data line sets. When odd-numbered data lines receive positive polarity signals, even-numbered data lines receive negative polarity signals, and vice versa in subsequent cycles. This inversion approach compensates for the inherent VCOM instability that would otherwise occur with even-numbered time-divisional data lines, thus resolving the contradiction between reduced device complexity and maintained reliability.
2Reliability
If dot inversion driving is applied to improve VCOM stability, then flicker is reduced, but compatibility with time division driving fails when data lines are even in number
Solution Approach 1:
The patent segments data lines into odd and even sets that can be independently controlled. This segmentation allows dot inversion driving to be applied within each segment while maintaining compatibility with time division driving across the entire even-numbered data line configuration. The segmentation enables both inversion driving benefits and time division driving compatibility to coexist.
Solution Approach 2:
Different inversion patterns are applied to different segments of data lines. Odd-numbered data lines follow one inversion pattern while even-numbered data lines follow the opposite inversion pattern. This local differentiation of quality (inversion behavior) allows the system to maintain VCOM stability through dot inversion while remaining compatible with time division driving for even-numbered data line configurations.
3Quantity of substance
If the number of data lines is increased to accommodate more pixels, then display resolution is improved, but the number of wire lines and EMI increases
Solution Approach 1:
The patent implements a multi-functional data line structure where each physical data line can be selectively connected to different input terminals through switch circuits. Data lines can be time-divisionally shared between multiple input terminals, reducing the total number of wire lines required. This universal usage of data lines allows increased pixel count without proportionally increasing wire line count and associated EMI.
Solution Approach 2:
The patent introduces a time dimension to the data line configuration by implementing time division driving. Instead of requiring one dedicated wire line per pixel column, the system reuses data lines across different time periods. This temporal multiplexing reduces the spatial dimension of wire line requirements, thereby reducing EMI while supporting higher pixel counts.
Data Source
AI summary
A method is provided for driving a liquid crystal display panel including first and second data line sets each including an even number of arrayed data lines, and a plurality of pixels sharing a common electrode having a constant potential. The method is composed of: time-divisionally selecting data lines from each of the first and second data line sets; and providing data signals on the selected data lines to write the data signals into the pixels therethrough. An order of selecting the data lines from each of the first and second data lines and polarities of the data signals written into the pixels are determined so that polarities of the data signals on the data lines selected from the first data line set are opposite to those of the data lines selected from the second data line set.