Voltage Detection Circuit for LCD Image Sticking Elimination
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Solution Overview
Problem
In liquid crystal display devices, the inconsistent timing of common voltage and data signals during power-on and power-off leads to voltage differences between pixel and common electrodes, causing image sticking and flicker, which affect display quality and reduce component lifespan.
Innovation Solution
A circuit and method that synchronize the timing of signals on the data line and common voltage signal terminal by using a voltage detecting module and a common signal writing module to equalize voltages during power transitions, employing a switch and timing controller to ensure voltage equality between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the common voltage signal VCOM and data signal VDATA are applied at different timings during power-on and power-off, then the display device can operate with standard timing sequences, but voltage differences occur between pixel electrode and common electrode causing image sticking and flicker
Solution Approach 1:
The patent applies preliminary action by detecting voltage levels before standard signal application and pre-adjusting the data signal timing. During power-on, the data signal is advanced to match the common voltage signal timing when voltage is below threshold. During power-off, the data signal is delayed until voltage drops below threshold. This preliminary voltage checking and timing adjustment prevents voltage differences before they cause image sticking or flicker, resolving the contradiction between standard operation timing and display quality stability.
2Reliability
If the timing of common voltage signal VCOM and data signal VDATA is synchronized during power-on and power-off, then image sticking and flicker are eliminated, but additional voltage detection and timing control circuits are required
Solution Approach 1:
The patent uses an intermediary approach by introducing a voltage detecting module that monitors the operating voltage and generates control signals based on threshold comparisons. This voltage detector acts as an intermediary between the power management system and the signal timing control, automatically adjusting data signal timing without requiring complex direct coordination between all signal generators. The intermediary voltage detection mechanism simplifies the overall control architecture while achieving reliable synchronization to eliminate image sticking and flicker.
3Object-affected harmful factors
If voltage equalization is performed during power transitions, then liquid crystal molecule polarization is prevented, but the timing control complexity increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the timing parameter of the data signal based on the voltage parameter detected during power transitions. When voltage exceeds thresholds during power-on or drops below thresholds during power-off, the timing controller modifies the data signal timing parameter to achieve voltage equalization. This parameter-based control approach prevents liquid crystal polarization by ensuring voltage equality without requiring complex mechanical or structural changes, using simple temporal parameter adjustment instead.
Data Source
AI summary
A circuit and method for eliminating image sticking during power-on and power-off, the circuit for eliminating image sticking during power-on and power-off includes a voltage detecting module and a common signal writing module; the voltage detecting module detects whether an operating voltage is lower than a first threshold voltage during power-on, and detects whether the operating voltage is lower than a second threshold voltage during power-off; and the common signal writing module writes, when the operating voltage is lower than the first threshold voltage during power-on or the operating voltage is lower than the second threshold voltage during power-off, a signal with a voltage equal to a voltage at a common voltage signal terminal at the same timing, to a data line.