Source Driver Segmentation for Dot Inversion Power Reduction
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Solution Overview
Problem
Conventional source drivers using the dot inversion driving method in TFT-LCDs face high power consumption due to the need for swing voltages twice that of the common voltage, and they require larger and more expensive CMOS transistors to handle both positive and negative voltages.
Innovation Solution
A source driver design with N latches, N+2 DACs of alternating NMOS and PMOS types, and N+1 output buffers, where switch units manage data paths to output voltages continuously in positive or negative polarity, reducing swing voltages and allowing for smaller, cheaper PMOS and NMOS designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dot inversion driving method is used to avoid liquid crystal polarization, then display quality is improved, but power consumption increases due to swing voltages being twice that of common voltage
Solution Approach 1:
The patent segments the voltage output function by dividing the data lines into two groups: even-numbered data lines (DL0, DL2, DL4) that output only positive voltages and odd-numbered data lines (DL1, DL3, DL5) that output only negative voltages. This segmentation allows each data line to maintain a single polarity, eliminating the need for large swing voltages while preserving the dot inversion driving method's display quality benefits.
2Adaptability or versatility
If DAC outputs both positive and negative voltages to handle dot inversion, then driving capability is improved, but transistor size increases and cost rises due to requirement for CMOS transistors
Solution Approach 1:
The patent segments the voltage generation function across different data lines, assigning positive voltage output to even-numbered data lines and negative voltage output to odd-numbered data lines. This allows the use of simpler PMOS transistors for positive voltage output and NMOS transistors for negative voltage output, eliminating the need for larger and more expensive CMOS transistors that can handle both polarities.
Data Source
AI summary
A source driver and an internal data transmission method are provided. The present invention employs specially designed switch units and creates specially designed data paths in a source driver, which matches with the driving method for dot invesion and the specially designed pixel array. When the dot inversion driving method is used on a pixel array of a specific design, each output buffer and digital-to-analog converter inside the source driver continuously output voltages of positive polarity and voltages of negative polarity, instead of switching between positive and negative polarities. Consequently, the swing voltages that the source driver outputs can be lowered, the power consumption can also be reduced accordingly, a smaller area is occupied, and the costs are reduced.