Liquid Crystal Display Pixel Electrode Contact Hole Design
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Solution Overview
Problem
Semi-transmissive liquid crystal display devices using in-plane switching (IPS) technology face challenges in maintaining high aperture ratio due to increased non-display sections and reduced transmissivity caused by contact holes for drive voltage application, leading to contrast inversion between transmission and reflection sections.
Innovation Solution
The design incorporates a shared pixel electrode for both transmission and reflection sections with independent counter electrodes and a comb-shaped electrode structure, where the pixel electrode is electrically coupled to the active element through strategically formed contact holes, minimizing inefficient display areas and optimizing the electric field control between counter electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact holes are formed in the counter electrode to apply drive voltage to the pixel electrode, then the pixel electrode can be electrically coupled to the active element, but non-display sections are increased and transmissivity is reduced
Solution Approach 1:
The patent moves the contact hole formation from the counter electrode (traditional approach) to the pixel electrode, changing the spatial dimension and location where the electrical connection is established. This dimensional shift allows the contact holes to be positioned in regions that do not compromise the display area, thereby maintaining transmissivity while achieving reliable electrical coupling between the pixel electrode and active element
Solution Approach 2:
The patent segments the electrode structure by separating the functions of the pixel electrode and counter electrode more distinctly. The pixel electrode is designed with integrated contact holes for voltage application, while the counter electrode focuses on generating the electric field. This segmentation allows optimization of each component's function without compromising overall performance
2Reliability
If a hole is made in the counter electrode to form a contact hole for applying drive voltage, then electrical connection is achieved, but the aperture ratio is reduced due to increased non-display sections
Solution Approach 1:
The patent relocates the contact hole formation to the pixel electrode rather than the counter electrode, changing the spatial dimension and functional location of the electrical connection. This allows contact holes to be positioned in non-critical areas that do not reduce the display aperture, thereby maintaining high aperture ratio while ensuring reliable electrical connection
Solution Approach 2:
The patent applies the contact hole concept to the pixel electrode structure, creating a copy of the electrical connection mechanism at a different location in the device architecture. This copied approach at the pixel electrode level achieves the same electrical coupling function without the negative effects of counter electrode contact holes
3Adaptability or versatility
If the transmission section is placed in normally white mode and the reflection section is placed in normally black mode, then the display modes are established, but contrast inversion occurs between the transmission and reflection sections
Solution Approach 1:
The patent inverts the traditional approach by making both the transmission and reflection sections operate in normally black mode rather than using normally white for transmission and normally black for reflection. This inversion of the display mode configuration eliminates the contrast inversion problem while maintaining the ability to support both transmission and reflection display functions
Solution Approach 2:
The patent applies homogeneous display mode configuration to both transmission and reflection sections, setting them both to normally black mode. This homogenization of operating modes across different display sections ensures consistent contrast characteristics and eliminates the contrast inversion issue that arises from mixed mode configurations
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 configuration enhances the aperture ratio by reducing light leakage and improving liquid crystal drive efficiency, effectively preventing contrast inversion and maintaining optimal image quality between transmission and reflection sections.
Implementation Method 1
apply an electric field between each pixel electrode PIX and counter electrode CT to rotate the liquid crystal in the substrate plane
Implementation Method 2
rotate the liquid crystal in the substrate plane in order to control the contrast
Implementation Method 3
a hole is made in a counter electrode CT to form a contact hole so that a drive voltage is applied to the pixel electrode PIX via the contact hole
Data Source
AI summary
A liquid crystal display device having a liquid crystal display panel includes a first substrate, a second substrate, and liquid crystal interposed between the first and second substrates. The first substrate includes an active element, a first insulating film formed on the active element, a plurality of first electrodes disposed on the first insulating film, a second insulating film disposed on the first electrodes, and a pixel electrode disposed on the second insulating film. The pixel electrode is electrically coupled to the active element via a portion defining a contact hole formed in a portion defining a clearance between the plurality of first electrodes.