Reflective Electrode Segmentation for LCD Brightness and Burn-in
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Solution Overview
Problem
Reflective and transflective liquid crystal display devices face challenges in achieving efficient light usage and brightness in reflection mode, with existing configurations resulting in suboptimal reflectance and display quality.
Innovation Solution
A liquid crystal display device design featuring a reflective electrode with a concave-convex surface structure, a transparent insulating layer, and a pixel electrode formed from transparent conductive material, where the reflective electrode is in an electrically floating state or at ground potential, and the pixel electrode is partially located in both reflective and transmissive regions, allowing for improved light scattering and alignment of liquid crystal molecules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective electrode is used in reflective and transflective liquid crystal display devices, then light reflection efficiency is improved, but display brightness and reflectance remain suboptimal
Solution Approach 1:
The reflective electrode is divided into multiple regions (first region within each pixel, second region between adjacent pixels, third region overlapping pixel electrodes). This segmentation allows different portions of the reflective electrode to serve different functions, optimizing both light reflection efficiency and display brightness across the entire display surface.
Solution Approach 2:
Different regions of the reflective electrode are assigned different functions: the first region provides local reflection within pixels, the second region provides inter-pixel reflection, and the third region provides overlapping reflection. This local differentiation optimizes the overall light utilization efficiency and display quality.
2Reliability
If voltage polarity is inverted in adjacent pixels, then liquid crystal alignment is improved, but voltage asymmetry causes burn-in in reflective regions
Solution Approach 1:
The reflective electrode is configured to maintain substantially the same time-averaged voltage in both maximum and minimum gray scale display states. This equipotential approach prevents voltage asymmetry that would otherwise cause burn-in, while still allowing liquid crystal alignment to be maintained through proper voltage application.
Solution Approach 2:
The voltage parameters of the reflective electrode are specifically controlled to achieve substantially equal time-averaged voltages in different gray scale states. This parameter optimization eliminates burn-in while maintaining proper liquid crystal alignment and display quality.
3Adaptability or versatility
If the reflective electrode is made transparent to allow transmission mode, then dual-mode display is achieved, but reflectance in reflection mode decreases
Solution Approach 1:
The reflective electrode is designed to serve multiple functions: it provides reflection in reflection mode while also allowing transmission in transmission mode. The electrode's specific configuration enables it to function effectively in both display modes without requiring separate electrode structures for each mode.
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 reflectance and achieves brighter displays in reflection mode while minimizing burn-in and improving transmittance in transmission mode, allowing for stable and efficient operation across various display modes.
Implementation Method 1
a vertical alignment liquid crystal layer provided between the first substrate and the second substrate
Implementation Method 2
a time average of voltage applied between the pixel electrode and the reflective electrode is substantially the same between a maximum gray scale display state and a minimum gray scale display state
Implementation Method 3
a reflective electrode including a first region located within each of the plurality of pixels and a second region located between any two pixels, of the plurality of pixels, adjacent to each other
Implementation Method 4
a transparent insulating layer provided to cover the reflective electrode
Data Source
AI summary
A liquid crystal display device includes a first substrate, a second substrate, a vertical alignment liquid crystal layer, and a plurality of pixels. Each of the pixels includes a reflective region for performing display in a reflection mode. The first substrate includes a reflective electrode including a first region located within each of the plurality of pixels and a second region located between any two pixels, of the plurality of pixels, adjacent to each other, a transparent insulating layer provided to cover the reflective electrode, and a pixel electrode formed from a transparent conductive material and provided on the transparent insulating layer in each of the plurality of pixels. The second substrate includes a counter electrode. Voltage of the same polarity is applied to the liquid crystal layer of any two pixels, of the plurality of pixels, adjacent to each other along a row direction, any two pixels, of the plurality of pixels, adjacent to each other along a column direction, or all of the plurality of pixels. A time average of voltage applied between the pixel electrode and the reflective electrode is substantially the same between a maximum gray scale display state and a minimum gray scale display state.