Source Drive Circuit VCOM Compensation for Residual Image Reduction
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Solution Overview
Problem
In liquid crystal display panels, especially in HADS mode, the large capacitance between the common voltage line and data line causes difficulties in recovering the common voltage, leading to errors in charging voltage, resulting in residual charges and residual images due to the increased change in common voltage VCOM.
Innovation Solution
A source drive circuit with a detection circuit to calculate the change value of the common voltage and a compensation circuit to generate a compensation data signal based on this change, which is then output to the pixel electrode, counteracting the voltage change and ensuring accurate charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the capacitance between the common voltage line and data line is large (as in HADS mode), then the display mode performance is improved, but the common voltage VCOM becomes more difficult to recover and residual images occur
Solution Approach 1:
The patent implements a feedback mechanism by detecting the common voltage VCOM at a detection point on the common voltage line and using this feedback signal to calculate and compensate for voltage changes. The detection circuit monitors the actual common voltage, and the compensation circuit adjusts the output signal based on the detected voltage change, creating a closed-loop control system that maintains voltage stability despite large capacitance effects in HADS mode.
Solution Approach 2:
The patent changes the parameter of the output signal by adding a compensation voltage component based on the detected common voltage change. The compensation circuit modifies the output signal parameters (voltage level) dynamically according to the detected common voltage variations, allowing the system to adapt to the large capacitance effects and maintain accurate pixel charging.
2Productivity
If the common voltage VCOM is pulled due to capacitance between common voltage line and data line, then the data signal transmission is enabled, but the charging voltage accuracy deteriorates and residual charges are caused
Solution Approach 1:
The patent applies preliminary anti-action by calculating the common voltage change based on the detected common voltage and then adding a compensation component to the output signal before it is applied to the pixel. This preemptive compensation counteracts the voltage pull effect caused by capacitance, ensuring that the pixel receives the correct charging voltage despite the anticipated voltage disturbance during data signal transmission.
3Manufacturing precision
If a detection circuit and compensation circuit are added to stabilize common voltage, then the charging voltage accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent merges the detection function and compensation function into an integrated circuit structure where the detection circuit and compensation circuit work together as a unified system. The detection circuit detects the common voltage, and the compensation circuit immediately processes this information to generate the compensated output signal, combining multiple functions into a cohesive design that minimizes additional complexity while achieving voltage stabilization.
Data Source
AI summary
A source drive circuit and a display device. The source drive circuit includes: a detection circuit, configure to detect a change value of a common voltage; and a compensation circuit, configured to obtain a compensation data signal based on a data signal and the change value of the common voltage, and output the compensation data signal to a pixel electrode of a display panel.