Reflective Electrode Segmentation for Transflective LCD Brightness
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Solution Overview
Problem
Reflective and transflective liquid crystal display devices face challenges in improving light utilization factor and brightness in reflective mode, with conventional designs having low transmittance and unstable liquid crystal alignment between pixels, leading to display faults.
Innovation Solution
The design includes a vertical alignment-type liquid crystal display device with a first substrate having a backplane circuit, interlayer insulating layers, reflective electrodes with concaved and convexed surface structures, and a pixel electrode formed of transparent conductive material, where the pixel electrode is located in both transmissive and reflective regions, and a second reflective electrode overlaps contact holes to enhance diffused reflection and alignment stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective liquid crystal display device uses a conventional single reflective electrode structure, then the device structure is simple, but the reflectance is low and display brightness is insufficient
Solution Approach 1:
The reflective electrode is divided into multiple separate reflective electrodes (first reflective electrode and second reflective electrode) positioned at different depths within the interlayer insulating layers. This segmentation allows each electrode to contribute independently to light reflection, increasing overall reflectance while maintaining manageable structural complexity through modular design
Solution Approach 2:
The patent introduces a vertical dimension to the electrode structure by placing reflective electrodes at different depths (first interlayer insulating layer and second interlayer insulating layer). This multi-layer vertical arrangement creates additional reflection interfaces, enhancing reflectance without significantly increasing horizontal structural complexity
2Reliability
If the pixel electrode is positioned only in the transmissive region, then the transmissive mode performance is optimized, but the reflective region has unstable liquid crystal alignment and low reflectance
Solution Approach 1:
The pixel electrode is designed to serve dual functions by being positioned in both the transmissive region and the reflective region. This multi-functional positioning allows the single electrode structure to contribute to both transmissive mode operation (when light passes through) and reflective mode operation (when light reflects), ensuring stable liquid crystal alignment and enhancing reflectance simultaneously
Solution Approach 2:
The patent merges the functions of separate electrodes for transmissive and reflective regions into a single pixel electrode structure that spans both regions. This consolidation simplifies the electrode system while ensuring uniform liquid crystal alignment across the entire pixel area, improving both alignment stability and reflective performance
3Productivity
If the contact holes are left empty without overlapping reflective electrodes, then the manufacturing process is simpler, but the reflective numerical aperture is reduced and display brightness is lowered
Solution Approach 1:
The second reflective electrode is preliminarily positioned to overlap the contact holes during the layer formation process. This preliminary placement ensures that the contact hole regions, which would otherwise be dead zones reducing reflective aperture, are converted into additional reflective areas. The overlapping structure is built in during normal manufacturing sequence, maintaining productivity while increasing reflective numerical aperture
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 improves reflective numerical aperture, increases reflectance, and enhances display brightness by ensuring stable liquid crystal alignment and full contribution of all display regions to both transmissive and reflective modes, reducing display faults and increasing contrast ratio.
Implementation Method 1
a vertical alignment-type liquid crystal layer provided between the first substrate and the second substrate
Implementation Method 2
a first reflective electrode provided on the first interlayer insulating layer, the first reflective electrode including a first region located in each of the plurality of pixels and a second region located between any two pixels adjacent to each other among the plurality of pixels... the first reflective electrode has a concaved and convexed surface structure
Implementation Method 3
a pixel electrode formed of a transparent conductive material, the pixel electrode being provided on the second interlayer insulating layer in each of the plurality of pixels
Implementation Method 4
a second reflective electrode provided on the second interlayer insulating layer so as to overlap the first contact hole as seen in a direction normal to a display surface
Data Source
AI summary
A liquid crystal display device includes a first substrate; a second substrate; and a vertical alignment-type liquid crystal layer. The first substrate includes a backplane circuit, a first interlayer insulating layer covering the backplane circuit, a first reflective electrode provided on the first interlayer insulating layer and including a first region located in each of pixels and a second region located between any two adjacent pixels, a second interlayer insulating layer covering the first reflective electrode, and a pixel electrode provided on the second interlayer insulating layer in each pixel. The pixel electrode is electrically connected with the backplane circuit in first and second contact holes formed in the first and second interlayer insulating layers. The first substrate further includes a second reflective electrode provided on the second interlayer insulating layer so as to overlap the first contact hole as seen in a direction normal to a display surface.