FFS LCD Pixel Circuit Voltage Stabilization
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Solution Overview
Problem
In fringe-field switching (FFS) LCD pixel circuits, the storage capacitor and liquid crystal capacitor are coupled to the same electrode, leading to interference between data signals and AC voltages, which prevents proper control of the voltage difference between the liquid crystal capacitor nodes.
Innovation Solution
The implementation of a pixel circuit design that includes a first switch, a storage circuit, a second switch, and a liquid crystal capacitor, where the first switch receives a data signal and the second switch receives a boost signal, both configured to control the liquid crystal capacitor, with opposite voltage polarities applied to adjacent pixel circuits to achieve polarity inversion and stabilize the voltage difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the storage capacitor and liquid crystal capacitor are coupled to the same electrode in FFS LCD pixel circuits, then the device complexity is reduced, but the data signal and AC voltage interfere with each other due to capacitor coupling effect
Solution Approach 1:
The pixel circuit is divided into two separate circuits located in adjacent columns. Each pixel circuit includes its own first switch, storage circuit, second switch, and liquid crystal capacitor. By segmenting the pixel circuits and applying opposite voltage polarities to adjacent circuits, the patent eliminates the capacitor coupling interference while maintaining structural efficiency
Solution Approach 2:
Adjacent pixel circuits are configured with opposite voltage polarities for their common voltages. When one pixel circuit applies a positive common voltage, the adjacent pixel circuit applies a negative common voltage. This inversion approach ensures that the AC voltages from adjacent circuits do not interfere with each other through the shared electrode, effectively resolving the signal interference problem
2Object-generated harmful factors
If the storage capacitor and liquid crystal capacitor are coupled to different electrodes, then the data signal and AC voltage do not interfere with each other, but the device complexity increases
Solution Approach 1:
The patent merges the storage capacitor and liquid crystal capacitor into a single integrated capacitor structure within each pixel circuit. The storage circuit is coupled with the liquid crystal capacitor through the first node point, allowing both functions to be achieved with a unified component rather than separate capacitors connected to different electrodes
Solution Approach 2:
The liquid crystal capacitor serves dual functions: it acts as both the storage capacitor for maintaining voltage and the liquid crystal capacitor for display operation. The same capacitor structure is used for both purposes, eliminating the need for separate capacitors and reducing overall device complexity while preventing signal interference
Data Source
AI summary
A pixel circuit includes a first switch, a storage circuit, a second switch, and a liquid crystal capacitor. The first node of the first switch is configured to receive a data signal, and the second node of the first switch is coupled with a first node point. The storage circuit is coupled with the first node point, and configured to receive a common voltage. The first node of the second switch is coupled with the storage circuit, and the second node of the second switch is configured to receive a boost signal. The liquid crystal capacitor is coupled between the first node point and the storage circuit. In response to the first switch is conducted, the second switch is conducted, or in response to the second switch is conducted, the first switch is conducted.