Charge-Sharing DAC for Flat Panel Gray Scale Generation
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Solution Overview
Problem
Conventional digital-analog converters (DACs) in flat panel display devices face issues with high power consumption and increased circuit area due to static current in R-strings and the need for analog buffers, which also lead to image quality deterioration and inefficient use of space, especially in systems on panel (SOP) processes.
Innovation Solution
The proposed solution involves a DAC that generates gray scale voltages through charge sharing between data lines and dummy data lines, eliminating the need for R-strings, decoders, and analog buffers, using parasitic capacitance components as sampling and holding capacitors to reduce power consumption and circuit area while improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional DAC with R-strings and analog buffers is used, then gray scale voltages can be generated, but power consumption increases and circuit area increases
Solution Approach 1:
The patent extracts and removes the R-strings and analog buffers from the conventional DAC structure. By eliminating these components that consume static power and occupy circuit area, the invention achieves lower power consumption and reduced circuit area while maintaining the gray scale voltage generation function through an alternative charge sharing mechanism.
Solution Approach 2:
The patent employs the parasitic capacitance inherently present in the data lines as holding capacitors, rather than requiring separate dedicated capacitor components. This self-service approach utilizes the existing electrical characteristics of the data lines to perform the capacitance function, thereby reducing additional circuit area and component count.
2Device complexity
If conventional DAC with R-strings is used, then gray scale voltages can be generated, but circuit area increases
Solution Approach 1:
The patent extracts and removes the R-strings and analog buffers from the conventional DAC structure. By eliminating these components that consume static power and occupy circuit area, the invention achieves lower power consumption and reduced circuit area while maintaining the gray scale voltage generation function through an alternative charge sharing mechanism.
Solution Approach 2:
The data lines serve multiple functions: they transmit digital data signals and simultaneously function as holding capacitors for the DAC operation due to their inherent parasitic capacitance. This multi-functionality eliminates the need for separate dedicated capacitor components, reducing circuit area while maintaining power efficiency.
3Reliability
If analog buffers are used in DAC, then voltage amplification is achieved, but image quality deteriorates due to output voltage difference between channels
Solution Approach 1:
The patent extracts and removes the analog buffers from the conventional DAC structure. By eliminating these components, the invention eliminates the source of output voltage differences between channels that cause image quality deterioration, while achieving voltage amplification through the charge sharing mechanism between data lines and dummy data lines.
Solution Approach 2:
The patent merges the voltage amplification function into the charge sharing process itself, rather than requiring a separate analog buffer stage. The charge sharing between data lines and dummy data lines inherently provides the necessary voltage amplification, eliminating the need for additional buffer circuits and ensuring uniform output across all channels.
4Loss of energy
If R-strings with large resistance values are used, then static current is reduced, but image quality deteriorates due to output voltage difference
Solution Approach 1:
The patent extracts and removes the R-strings from the conventional DAC structure entirely. By eliminating this component, the invention achieves zero static current consumption from R-strings while avoiding the image quality deterioration that occurs with large resistance values, as the charge sharing mechanism does not rely on resistive voltage division.
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 minimizes power consumption and circuit area, enhances image quality by eliminating voltage differences between channels, and optimizes space usage, even in SOP processes, by leveraging charge sharing between data and dummy data lines.
Implementation Method 1
a gray scale generator for generating gray scale voltages corresponding to digital data input through charge sharing between a plurality of data lines and a plurality of dummy data lines
Implementation Method 2
using parasitic capacitance components as sampling and holding capacitors
Data Source
AI summary
A digital-analog converter (DAC) including: a gray scale generator for generating gray scale voltages corresponding to digital data input through charge sharing between a plurality of data lines and a plurality of dummy data lines; a switching signal generator for providing operation control signals for a plurality of switches of the gray scale generator; and a reference voltage generator for generating reference voltages and for providing the reference voltages to the gray scale generator. According to the present invention, the digital-analog converter uses capacitance components existing in the respective data lines and the dummy data lines as a sampling capacitor and a holding capacitor to generate desired gray scale voltages through charge sharing between the data lines and the dummy data lines, thereby reducing area and power consumption over an existing R-string type of DAC.