Flat Panel Data Driver Charge Sharing Circuit
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Solution Overview
Problem
Conventional data drivers for flat panel displays face challenges with high power consumption and increased circuit area due to static current in R-strings and image quality deterioration from non-uniform transistor threshold voltages and mobility, especially when implementing higher gray scale bits and using system on panel (SOP) processes.
Innovation Solution
The data driver utilizes parasitic capacitance components in data lines and capacitance components in pixels and dummy pixels as sampling and holding capacitors to generate gray scale voltages through charge sharing, reducing circuit area and power consumption, and eliminating the need for an analog buffer amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If R-strings with large resistance values are used to reduce static current, then power consumption is reduced, but image quality deteriorates due to output voltage difference between channels
Solution Approach 1:
The invention extracts and eliminates the R-strings (resistance strings) from the DAC structure entirely. Instead of using R-strings to generate gray scale voltages, the patent uses a switch array that directly connects reference voltages to data lines, removing the source of static current consumption while maintaining voltage accuracy across channels
Solution Approach 2:
The patent uses multiple identical switch arrays (one for each color channel: R, G, B) that replicate the same switching mechanism. Each switch array independently controls its color channel without sharing R-strings, ensuring uniform threshold voltages and mobility across channels while eliminating the need for large resistance values
2Measurement precision
If 6-64 switches are built in respective channels to implement 6-bit gray scale, then gray scale precision is improved, but circuit area is greatly increased
Solution Approach 1:
The patent segments the gray scale generation into two independent parts: (1) a single 6-64 switch array that generates all gray scale voltages, and (2) three simple switch arrays (one per color channel) that select and apply the appropriate gray scale voltage. This segmentation reduces the number of switches in each color channel from 6-64 to just 6 switches, dramatically reducing circuit area while maintaining 6-bit gray scale precision
Solution Approach 2:
The single 6-64 switch array serves all three color channels (R, G, B) universally. It generates all 64 gray scale voltages that are then shared across all color channels through the simpler per-channel switch arrays, eliminating the need for separate 6-64 switch arrays in each channel and reducing total circuit area
3Stability of the object's composition
If analog buffer is used as amplifier in respective channels, then output voltage uniformity is improved, but device complexity increases due to threshold voltage and mobility variations
Solution Approach 1:
The patent replaces the complex analog buffer amplifiers with simple switch arrays that directly connect reference voltages to data lines. These simple switches, while having short conduction periods during the horizontal period, are sufficient for the application and eliminate the need for complex analog buffering circuitry, reducing device complexity while maintaining output uniformity through precise switching control
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 approach significantly reduces power consumption and circuit area while maintaining image quality by using charge sharing to generate gray scale voltages, effectively addressing the limitations of conventional data drivers and SOP processes.
Implementation Method 1
the data driver uses parasitic capacitance components existing in at least two data lines of a plurality of data lines on a panel of the display device and capacitance components in pixels and dummy pixels connected to the respective data lines as a sampling capacitor and a holding capacitor
Implementation Method 2
to generate the gray scale voltages through charge sharing between the data lines
Data Source
AI summary
A flat panel display device including: a display region including pixels connected to scan lines and data lines; a dummy display region including dummy pixels connected to at least two dummy scan lines and the data lines; a scan driver for providing scan signals and dummy scan signals to the scan lines and the dummy scan lines; a data driver for generating gray scale voltages corresponding to input digital data and providing them to corresponding pixels through the data lines; and a timing controller for controlling the scan driver and the data driver, wherein the data driver uses parasitic capacitance components existing in at least two data lines and capacitance components in the pixels and the dummy pixels connected to the at least two data lines, as a sampling capacitor and a holding capacitor to generate the gray scale voltages through charge sharing between the at least two data lines.