Gamma-Reference Voltage Circuit Thermal Compensation for LCD Kickback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid crystal display (LCD) devices suffer from image sticking due to variations in kickback voltage across different gradations, particularly exacerbated by temperature changes, which affect the capacitance of the liquid crystal layer and lead to display quality degradation.
Innovation Solution
A gamma-reference-voltage generating circuit with thermal compensation features, utilizing resistor strings and thermistors to adjust gamma-reference-voltages based on temperature, reducing the kickback voltage deviation between white and black gradations by decreasing gamma-reference-voltages for white gradations and maintaining them for black gradations as temperature increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gamma-reference-voltages are maintained constant across temperature variations, then circuit simplicity is preserved, but kickback voltage deviations increase causing image sticking
Solution Approach 1:
The patent changes the resistance values of thermistors based on temperature variations to dynamically adjust gamma-reference-voltages. Specifically, the first thermistor (Rp) increases resistance with temperature while the second thermistor (Rn) decreases resistance, thereby compensating for kickback voltage deviations caused by temperature changes without requiring complex control circuits
Solution Approach 2:
The patent introduces thermistors as intermediary components between the voltage sources and the liquid crystal capacitor. These thermistors act as passive temperature-sensitive elements that automatically adjust voltage distribution according to temperature, eliminating the need for active temperature sensing and control circuits
2Temperature
If thermal compensation components are added to compensate for temperature variations, then display quality is improved, but device complexity increases
Solution Approach 1:
The patent utilizes the temperature-dependent resistance characteristics of thermistors to automatically compensate for temperature variations. The first thermistor Rp has positive temperature coefficient while the second thermistor Rn has negative temperature coefficient, creating complementary effects that stabilize display performance across temperature ranges
Solution Approach 2:
The patent converts the harmful effect of temperature variations into a beneficial compensation mechanism by exploiting the natural temperature-dependent resistance changes of thermistors. Instead of fighting against temperature effects through active control, the circuit uses passive thermal response to automatically adjust voltages in the desired direction
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 solution improves display quality by reducing kickback voltage deviations across gradations, thereby minimizing image sticking and maintaining display characteristics even at varying temperatures.
Implementation Method 1
The first thermal compensation section exhibits a resistance value that increases as a function of an increase of temperature
Implementation Method 2
The second thermal compensation section exhibits a resistance value that decreases as a function of an increase of temperature
Implementation Method 3
the capacitance of the liquid crystal capacitor depends on the voltage across the liquid crystal capacitor due to the dielectric anisotropy of the liquid crystal
Data Source
AI summary
A first resistor string provides a plurality of first polarity gamma-reference-voltages. A second resistor string provides a plurality of second polarity gamma-reference-voltages. A first main-thermal compensation section exhibits a resistance value that increases with an increase of temperature. A second main-thermal compensation section has a resistance value that is decreases with an increase of temperature. Thus, gamma-reference-voltages corresponding to white gradation are decreased and gamma-reference-voltages corresponding to black gradation are maintained, so that a deviation of kickback voltage corresponding to the white gradation is decreased.