Display Driving Circuit Pre-Charging for LCD Stability
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Solution Overview
Problem
In liquid crystal display (LCD) panels, particularly in TFT-LCDs, the insufficient charging time leads to voltage switching issues between positive and negative polarities, causing liquid crystal polarization and display abnormalities due to large voltage differences across pixel electrodes.
Innovation Solution
A driving circuit with signal processing and controlled switching circuits is introduced, where each sub-pixel has a display switching circuit and a reference switching circuit, allowing for controlled voltage switching between positive and negative polarities to prevent polarization, ensuring efficient charging by alternating the display and reference voltage connections based on control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage on the pixel electrode is directly switched from positive polarity to negative polarity, then the display can avoid liquid crystal polarization, but the charging time is insufficient and the voltage cannot be switched to the target voltage within the limited charging time
Solution Approach 1:
The patent applies preliminary action by introducing a reference voltage terminal that pre-charges pixel electrodes to a reference voltage before the actual display voltage is applied. This pre-charging step ensures that when the display voltage is switched, the voltage difference is reduced and sufficient charging time is available within the limited display frame period, preventing display abnormalities while maintaining timely voltage switching
Solution Approach 2:
The reference voltage terminal acts as an intermediary between the positive and negative polarity voltages. Instead of directly switching between extreme voltage values, the pixel electrode first charges to the reference voltage (an intermediate state), which reduces the voltage difference and allows proper charging within the limited time, thereby solving the contradiction between avoiding polarization and having sufficient charging time
2Reliability
If the voltage on the pixel electrode is directly switched between positive and negative polarity, then liquid crystal polarization can be avoided, but the large voltage difference causes insufficient charging
Solution Approach 1:
The reference voltage terminal performs preliminary charging of the pixel electrode before the display voltage is applied. This pre-charging action reduces the subsequent voltage difference that needs to be charged, thereby improving charging efficiency while still preventing liquid crystal polarization through proper voltage switching
Solution Approach 2:
The reference voltage serves as an intermediary state that improves charging efficiency. By first charging to the reference voltage and then to the final display voltage, the charging process is divided into two stages with smaller voltage differences, significantly improving overall charging efficiency compared to direct switching between extreme polarities
Data Source
AI summary
Provided are a driving circuit and a display driving device, comprising: when a signal processing module acts on any control signal, only the path of the display signal outputting to the sources of transistors in a portion of the corresponding sub-pixels is turned on, enabling this portion to complete the display of sub-pixels. At the same time, the reference voltage is connected to the reference voltage terminal of the other portion of the corresponding sub-pixels, so that the pixel electrode of the other portion is charged to the reference voltage. On such basis, before each control signal is inverted, a portion of the sub-pixels is in operation, and the other portion is precharged to the reference voltage, thereby improving the charging efficiency of the pixel electrodes, and ensuring that the voltage on the pixel electrodes can be switched to a target voltage.