Array Substrate Electrode Layout for Uniform LCD Pixel Brightness
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Solution Overview
Problem
In large-size liquid crystal display panels, the resistance of ITO materials leads to voltage attenuation along the ITO slit, resulting in differences in electric fields at the near and far ends of the pixel, causing uneven display brightness across the same pixel.
Innovation Solution
The array substrate design includes a first and second metal layer, a first and second transparent conductive layer, with pixel electrode branches extending along data lines and connected to TFT drains, allowing for improved electric signal transmission and uniformity by dividing each pixel region into sub-pixels with separate electrode branches and a bridging portion to reduce signal attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If ITO materials are used for pixel electrodes and common electrodes to allow backlight transmission, then transmittance is improved, but voltage attenuation occurs along the ITO slit resulting in non-uniform electric fields and uneven display brightness
Solution Approach 1:
The pixel electrode is divided into multiple segments (first pixel electrode and second pixel electrode) separated by the common electrode. Each segment is independently connected to the TFT, creating separate electrical pathways that reduce the length of individual ITO conductors and minimize voltage attenuation, thereby improving electric field uniformity while maintaining high transmittance
Solution Approach 2:
The common electrode serves as an intermediary structure that both blocks light (forming black matrix regions) and provides electrical connection pathways. By using the common electrode as both a light-blocking element and an electrical conductor, the patent reduces the need for long ITO transmission paths while maintaining optical performance
2Area of stationary object
If the ITO slit length in the longitudinal direction is increased for large-size products with large pixels, then pixel area is improved, but resistance increases causing greater voltage attenuation and brighter non-uniformity
Solution Approach 1:
The pixel electrode is segmented into multiple parts (first pixel electrode and second pixel electrode) that are spatially separated by the common electrode. This segmentation allows large pixel areas to be achieved while keeping the electrical connection paths short, as each segment connects to the TFT through a separate, shorter ITO conductor rather than one long conductor spanning the entire pixel
Solution Approach 2:
The patent introduces a new spatial dimension by placing the common electrode between the first and second pixel electrodes in the vertical direction. This dimensional arrangement allows the pixel to achieve large area in the horizontal direction while maintaining short vertical connection paths to the TFT, effectively decoupling pixel area from conductor length
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the uniformity of display brightness across the pixel by reducing signal attenuation and improving the transmission path, ensuring consistent brightness from one end of the pixel to the other.
Implementation Method 1
Under external electric fields, arrangement directions of liquid crystal molecules will change to different degrees, such that different grayscale brightness may be controlled by controlling the amount of light passing through the liquid crystal. Generally, when an external electric field has a certain intensity, an orientation change of liquid crystal molecules will be occurred. The orientation change of liquid crystal molecules is called a fredericksz transition.
Data Source
AI summary
Some embodiments of the present disclosure provide an array substrate and a display pane. Multiple pixel electrode branches in a corresponding one of the pixel regions are divided into a first pixel electrode branch and a second pixel electrode branch by a corresponding one of the metal common electrodes. The first pixel electrode branch and the second pixel electrode branch, which are located in different pixel regions and which are adjacent to each other, are respectively connected to different drains of the same TFT. In each pixel region, an end of the first pixel electrode branch close to a corresponding one of the scan lines is connected to a corresponding one of the TFTs, and an end of the second pixel electrode branch close to another corresponding one of the scan lines is connected to another corresponding one of the TFTs.