Fringe Field Switching LCD Array Substrate Test Pixel Design
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Solution Overview
Problem
The existing array substrate for fringe field switching mode liquid crystal displays (LCDs) cannot measure the properties of thin film transistors in the display area due to the structural configuration, where the common electrodes cover the pixel electrodes, preventing the application of gate and data signal voltages necessary for testing.
Innovation Solution
An array substrate design with non-display areas surrounding the display area, including test pixel areas with test thin film transistors and test electrodes, allows for the testing of thin film transistors by applying signal voltages through test electrodes, enabling the measurement of transistor properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If common electrodes are formed over the entire display area including pixel electrodes, then the fringe field switching mode LCD can be implemented with improved viewing angle, but the properties of thin film transistors cannot be measured due to lack of access for applying gate and data signal voltages
Solution Approach 1:
The display area is segmented into regular pixel areas and test pixel areas. The test pixel areas are specifically designed to provide access to thin film transistor terminals for measurement purposes, while regular pixel areas maintain the standard configuration for display functionality. This segmentation allows simultaneous achievement of both viewing angle improvement and transistor property measurement capability.
Solution Approach 2:
Test electrodes are introduced as intermediary elements in the test pixel areas. These test electrodes serve as mediators to apply gate and data signal voltages to the thin film transistors for measurement purposes, without interfering with the normal operation of the display. The test electrodes enable voltage application while the common electrode structure remains intact for fringe field switching operation.
2Difficulty of detecting and measuring
If test pixel areas are added around the display area, then thin film transistor properties can be measured, but the device structure becomes more complex
Solution Approach 1:
The test pixel areas are merged with the existing array substrate structure, sharing common elements such as the substrate, common electrode, and surrounding structures. The test pixel areas use the same thin film transistor configuration and materials as regular pixel areas, differing only in the provision of accessible test electrodes. This merging approach minimizes additional complexity while enabling measurement functionality.
Solution Approach 2:
The test pixel areas serve multiple functions: they provide measurement capability for thin film transistor properties, verify manufacturing quality, and maintain consistency with the regular pixel structure for fringe field switching operation. The same basic structure serves both display and testing purposes, reducing overall system complexity.
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
Enables the detection of defects and measurement of thin film transistor properties, improving the quality and manufacturing process of fringe field switching mode LCDs by allowing for the testing of switching transistors and ensuring proper functionality.
Implementation Method 1
a liquid crystal layer 11 is inserted between the upper and lower substrates 9 and 10... the liquid crystal layer 11 is driven by a horizontal electric field L formed by the common electrode 17 and the pixel electrode 30
Implementation Method 2
when an electric field is applied to the liquid crystals, the molecular arrangement direction of the liquid crystals is changed
Data Source
AI summary
An array substrate for a fringe field switching mode liquid crystal display, and the display are discussed. According to an embodiment, the array substrate includes a display area including pixel areas defined gate lines and data lines crossing the gate lines, each pixel area including a switching thin film transistor and a plate-shaped pixel electrode connected to the switching thin film transistor, the display area of the display further including a common electrode having openings in correspondence with the pixel electrodes, the common electrode being formed over the pixel electrodes throughout an entire area of the display area; and first through fourth non-display areas surrounding the display area and including pixel areas surrounding the display area, wherein each test pixel area includes a test thin film transistor and a test electrode connected to the corresponding test thin film transistor.