LCD Panel Overvoltage Driving Table for Signal Delay Compensation
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Solution Overview
Problem
In liquid crystal displays (LCDs), signal delay due to increasing impedance in data lines leads to undercharging of pixels, causing color shifts during gray level changes, especially noticeable in two-color mixing scenarios.
Innovation Solution
The implementation of an overvoltage driving unit with multiple tables (original, first, and second overvoltage driving tables) that adjust voltages based on gray level differences between sub-pixels, coupled with a data analysis unit and storage, to manage voltage differences and prevent overcharging, thereby reducing color shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of output channels of the data driving unit increases, then the data driving unit can drive more pixels, but the impedance of the data lines increases and signal delay increases causing undercharge of pixels
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the voltage level of data signals based on the gray level values of adjacent sub-pixels. When a large gray level difference is detected between adjacent sub-pixels, the system increases the voltage amplitude to compensate for signal delay and prevent undercharge, thus maintaining signal accuracy while driving more pixels
2Quantity of substance
If the impedance of data lines increases, then more pixels can be driven, but the degree of delay of data signal increases causing undercharge of pixel
Solution Approach 1:
The patent implements preliminary anti-action by detecting the gray level difference between adjacent sub-pixels before signal transmission and proactively adjusting the voltage amplitude accordingly. This preemptive adjustment compensates for the anticipated signal delay caused by high impedance, ensuring that pixels receive the correct charge despite the time loss in transmission
3Productivity
If voltage change of pixel electrode becomes slow due to signal delay, then more pixels can be addressed, but the charge of pixel sharply reduces causing color shift
Solution Approach 1:
The patent changes the voltage parameter dynamically based on detected gray level differences. When adjacent sub-pixels have significantly different gray levels, the system increases voltage amplitude to ensure the pixel electrode reaches the correct voltage level despite slow charging, thereby maintaining gray level accuracy while addressing more pixels
4Reliability
If overvoltage is applied to compensate for signal delay, then pixel charging is improved, but next sub-pixel may be overcharged causing color shift
Solution Approach 1:
The patent applies local quality by making the voltage amplitude adjustment localized to specific sub-pixels based on their individual gray level differences with adjacent sub-pixels. Each sub-pixel receives a customized voltage level tailored to its specific charging needs, preventing overcharge of subsequent sub-pixels while ensuring adequate charge for pixels that require it
Data Source
AI summary
A liquid crystal display (LCD) panel includes a plurality of pixels, scan lines, data lines crisscrossing with the scan lines, a data driving unit that drives the data lines, an overvoltage driving unit coupled to the data driving unit, a data analysis unit coupled to the overvoltage driving unit and reading gray level of each of sub-pixels, an original overvoltage driving table, and a first overvoltage driving table. Each of the pixels belonging to a same column receives data of a same data line, and each of the pixels includes three sub-pixels controlled by three adjacent scan lines one by one. The original overvoltage driving table and the first overvoltage driving table are coupled to the data analysis unit. When an input signal driving the first overvoltage driving table is same as an input signal driving the original overvoltage driving table, partial voltages driving the data lines and corresponding to the first overvoltage driving table is greater than voltage driving the data lines and corresponding to the original overvoltage driving table. In a same frame image, when gray level of a current sub-pixel is greater than gray level of a previous sub-pixel of a same data line with the current sub-pixel, and gray level difference between the two sub-pixels is greater than a first threshold value, the overvoltage driving unit drives the current sub-pixel according to the first overvoltage driving table.