LCD Subpixel Charging via Extended Signal Duration
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Solution Overview
Problem
In liquid crystal displays (LCDs), the last sub-pixel in a sequence often experiences insufficient charging due to RC time constant limitations, leading to inadequate charging or discharging, as it receives charge for a shorter duration than preceding sub-pixels when using a shared data line and time multiplexing.
Innovation Solution
The LCD design includes a controller that ensures the last sub-pixel receives its data signal level for a longer period during the charging time, with a demultiplexer and gate driver configuration that extends the charge transfer time for the last sub-pixel, ensuring all sub-pixels are charged uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If time multiplexing is used to share data lines among multiple sub-pixels, then the number of data driving chips is reduced, but the last sub-pixel in the sequence experiences insufficient charging due to shorter charging time
Solution Approach 1:
The patent applies preliminary action by extending the charging time for the last sub-pixel in advance. The data signal level is maintained for an extended period specifically for the last sub-pixel to ensure sufficient charging before the gate signal is deactivated. This preliminary extension of charging time prevents insufficient charging of the last sub-pixel while maintaining time multiplexing benefits.
2Productivity
If data signal levels are sequentially applied to all sub-pixels within one gate-on time, then all sub-pixels can be driven simultaneously, but the last sub-pixel does not have sufficient time to receive charge due to RC time constant limitations
Solution Approach 1:
The patent applies local quality by providing differentiated charging time to different sub-pixels based on their position in the sequence. The last sub-pixel receives an extended charging period specifically tailored to its needs, while other sub-pixels maintain their original charging duration. This localized adjustment ensures adequate charging for the last sub-pixel without compromising the overall driving speed.
Solution Approach 2:
The patent changes the time parameter dynamically based on the sub-pixel position in the sequence. The data signal level duration is extended specifically for the last sub-pixel to compensate for RC time constant limitations. This parameter change allows the system to maintain high productivity while ensuring sufficient charging time for the last sub-pixel.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration ensures that all sub-pixels in a main pixel group are charged sufficiently and uniformly, improving the display's image quality by ensuring the last sub-pixel receives its data signal for a sufficient period, thereby addressing the charging inefficiencies in traditional LCDs.
Implementation Method 1
a liquid crystal display (LCD) generates an electric field in a liquid crystal layer disposed between two display substrates. The LCD adjusts the intensity of an electric field in each of plural pixel areas to regulate the transmittance of light passing through the liquid crystal layer
Implementation Method 2
a pixel-electrode of the pixel unit is charged with a voltage corresponding to the data signal and a desired electric field is then formed between the pixel-electrode and an opposed common electrode
Data Source
AI summary
A demultiplexer is provided within a liquid crystal display (LCD) to transfer respective data levels of a time multiplexed data signal to respective sub-pixels within a pixel group. The last of sequentially activated switches in the demultiplexer is activated for the longest time so as to provide sufficient time for charge to transfer from the demultiplexer to a subsidiary data line (SDL) of the last supplied sub-pixel and from that last SDL through a respective TFT of the last sub-pixel to the last supplied sub-pixel.