LCD DAC Decoder Architecture for Accurate Pixel Voltage Interpolation
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Solution Overview
Problem
Conventional digital-to-analog converters for liquid crystal displays face challenges with larger circuit area, higher cost, and increased errors in pixel voltage due to interpolation, which affect display quality.
Innovation Solution
A digital-to-analog converter design incorporating a decoder apparatus with first and second decoder units and an operational amplifier, which selects corresponding voltages from border voltages based on gray level values to generate pixel voltages through interpolation, reducing circuit area and error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the gray level has more bits and the grade of Gamma voltage resistor string increases to improve display quality, then the display quality is improved, but the circuit area becomes large and cost increases
Solution Approach 1:
The patent segments the gray level range into multiple sub-ranges, with each sub-range having its own dedicated decoder unit. This allows the system to handle high-bit gray levels without requiring a full high-grade Gamma voltage resistor string across the entire range, thereby reducing circuit area while maintaining display quality in each segment.
Solution Approach 2:
The patent introduces a new dimension by adding a second decoder unit that operates in parallel with the first decoder unit. This multi-dimensional approach allows the system to select from multiple voltage sets based on the gray level value, achieving high precision without requiring a single large-scale resistor string.
2Ease of manufacture
If interpolation of each digital code is performed to reduce the cost of the D/A converter, then the cost is reduced, but the error in pixel voltage increases and display quality decreases
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing voltage values in lookup tables for different gray level ranges. The decoder units directly retrieve these pre-computed values rather than performing real-time interpolation, which reduces both computational error and manufacturing complexity while maintaining voltage accuracy.
3Manufacturing precision
If a high-grade Gamma voltage resistor string is used to improve pixel voltage accuracy, then the pixel voltage accuracy is improved, but the circuit area and cost increase
Solution Approach 1:
The patent divides the high-grade Gamma voltage resistor string requirement into multiple lower-grade segments, each handled by dedicated decoder units for specific gray level ranges. This segmentation maintains pixel voltage accuracy within each range while reducing overall circuit complexity and area requirements.
Solution Approach 2:
The patent applies local quality by providing different levels of voltage precision tailored to different gray level ranges. Each decoder unit is optimized for its specific range, using appropriate voltage sets and interpolation strategies locally, rather than applying uniform high precision across all ranges, thereby reducing overall device complexity.
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
The solution achieves a smaller circuit area, lower cost, reduced pixel voltage errors, and improved display quality by effectively interpolating digital codes and managing the non-linear relationship between pixel voltage and gray level.
Implementation Method 1
The operational amplifier generates a pixel voltage whose level ranges between the first and the second voltage accordingly
Data Source
AI summary
A digital-to-analog (D/A) converter comprises a decoder apparatus and an operational amplifier. The decoder apparatus comprises first and second decoder unit. The first decoder unit selects a voltage of first voltage set as first and second voltage in response to a value of first gray level set. The second decoder unit selects first border voltage of second voltage set as the first and the second voltages and second border voltage of that as the first and the second voltages in response to the maximum and the minimum value of second gray level set respectively. The second decoder unit further selects the first and the second boarder voltage as the first and the second voltage respectively in response to an intermediate value of the second gray level set. The operational amplifier generates a pixel voltage having level between the first and the second voltage accordingly.