Common Voltage Adjusting Circuit for TFT-LCD Flicker Control
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Solution Overview
Problem
The existing common voltage adjusting circuits for TFT-LCDs face challenges in accurately controlling the common voltage due to variations in environmental temperatures, leading to inaccurate voltage generation and potential flicker issues.
Innovation Solution
A common voltage adjusting circuit incorporating a delta adder, sigma adder, sigma latch, quantization circuit, low-pass filter, diodes, and a buffer, which receives binary signals to accurately control voltages provided to the common electrode, independent of temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional common voltage adjusting circuit is used, then the circuit structure is simple, but the voltage control precision deteriorates due to temperature variations
Solution Approach 1:
The patent replaces the conventional resistor-based voltage division mechanism with a digital-to-analog conversion approach using a code generator and capacitor array. This substitution eliminates the temperature-sensitive resistor parameters while achieving precise voltage control through digital code manipulation, thereby improving voltage control precision without significantly increasing overall circuit complexity.
Solution Approach 2:
The patent changes the control parameter from analog resistor ratios to digital code values. By using a code generator that converts digital codes into corresponding voltage levels through capacitor charging/discharging control, the system achieves temperature-independent voltage precision. The parameter transformation from continuous analog resistance to discrete digital codes eliminates thermal drift effects.
2Stability of the object's composition
If the common voltage varies with temperature, then the adaptability to environmental conditions improves, but the stability of voltage levels deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the code generator continuously monitors and adjusts the common voltage based on temperature conditions. The system uses temperature compensation logic that detects environmental changes and automatically adjusts the capacitor charging/discharging characteristics to maintain stable voltage levels, thereby achieving both stability and adaptability.
Solution Approach 2:
The patent dynamically changes the electrical parameters of the capacitor array based on temperature conditions. By adjusting the charging/discharging rates and voltage levels according to temperature sensors or environmental detection, the system maintains voltage stability across different temperature ranges, achieving adaptability without sacrificing stability.
3Reliability
If the inversion drive method is used, then the liquid crystal material deterioration is prevented, but the flicker problem worsens due to voltage variations
Solution Approach 1:
The patent uses feedback control to compensate for voltage variations that cause flicker. The code generator continuously adjusts the common voltage based on detected conditions, ensuring that the voltage remains within the optimal range for the inversion drive method. This feedback mechanism eliminates flicker while maintaining the benefits of inversion drive for liquid crystal material protection.
Solution Approach 2:
The patent dynamically adjusts the voltage parameters during inversion drive operation. By changing the common voltage levels and transition rates according to the specific inversion drive requirements and environmental conditions, the system prevents flicker while maintaining material reliability. The parameter adjustment ensures smooth transitions and stable operation throughout the inversion cycle.
Data Source
AI summary
A common voltage adjusting circuit (200) includes a delta adder (21), a sigma adder (22), a sigma latch (23), and a quantization circuit (24). The delta adder includes a first input terminal configured for receiving a binary signal, a second input terminal, and an output terminal. The sigma adder includes a first input terminal connected to the output terminal of the delta adder, a second input terminal, and an output terminal. The sigma latch includes a first input terminal connected to the output terminal of the sigma adder, and an output terminal connected to the second input terminal of the delta adder and the second input terminal of the sigma adder. The quantization circuit includes a first input terminal connected to the output of the sigma latch, and an output terminal connected to a common electrode of a TFT-LCD.