Transflective VA LCD With Common Electrode Ribs For Viewing Angle
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Solution Overview
Problem
Conventional liquid crystal display (LCD) devices face issues with narrow viewing angles, low contrast ratios, high power consumption, and reduced luminance due to limitations in transmissive, reflective, and transflective modes, particularly in achieving a balance between wide viewing angles and high luminance.
Innovation Solution
A transflective VA mode LCD device is designed with first and second substrates having transmissive and reflective areas, featuring multiple domains generated by electric field distorting units, including rib structures on the common electrode to improve viewing angles and aperture ratios, while minimizing disclination areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transmissive type LCD device with backlight assembly is used, then high luminance can be achieved, but power consumption increases significantly
Solution Approach 1:
The pixel electrode is segmented into transmissive and reflective regions, allowing different areas to serve different functions. The transmissive region allows backlight to pass through for high luminance display, while the reflective region reflects ambient light to reduce backlight dependency, thereby lowering power consumption while maintaining acceptable luminance levels.
Solution Approach 2:
Different regions of the pixel electrode are assigned different optical properties (transmissive vs. reflective). The transmissive region uses transparent ITO for high light transmission, while the reflective region uses reflective material for ambient light reflection. This local differentiation allows the device to optimize both luminance and power consumption by utilizing available ambient light in reflective mode.
2Use of energy by moving object
If a reflective type LCD device is used, then power consumption is reduced, but luminance decreases and image display is impossible in dark environments
Solution Approach 1:
The pixel electrode is divided into transmissive and reflective regions. The transmissive region ensures sufficient luminance output by allowing backlight to pass through, while the reflective region reduces power consumption by utilizing ambient light. This segmentation allows the device to maintain acceptable luminance levels even in dark environments while still achieving power savings in ambient light conditions.
Solution Approach 2:
The pixel electrode structure serves multiple functions: it acts as both a transmissive electrode (using ITO) and a reflective electrode (using reflective material) within the same device. This multi-functionality allows the LCD to operate effectively in both transmissive mode (high luminance) and reflective mode (low power consumption), adapting to different environmental lighting conditions.
3Adaptability or versatility
If pixel electrode ribs or common electrode ribs are added to create multiple domains, then viewing angle is improved, but aperture ratio and luminance decrease due to occupied area
Solution Approach 1:
The invention extracts the electric field distorting function from the pixel electrode ribs and relocates it to the common electrode ribs only. By removing the ribs from the pixel electrode and keeping them only on the common electrode, the aperture ratio is improved while still achieving multiple domain formation for wide viewing angle. The common electrode ribs generate oblique electric fields that create multiple domains without the additional area occupation of pixel electrode ribs.
4Adaptability or versatility
If multiple domains are created to improve viewing angle, then viewing angle widens, but disclination areas increase and further reduce luminance
Solution Approach 1:
By removing pixel electrode ribs and keeping only common electrode ribs, the number of domain boundaries is reduced. The common electrode ribs alone are sufficient to generate the necessary oblique electric fields for multiple domain formation. This reduction in rib structures minimizes disclination areas between domains, thereby reducing light scattering and improving overall luminance while maintaining wide viewing angle.
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
The solution enhances viewing angles and aperture ratios by creating multiple domains in the liquid crystal layer, optimizing luminance and power efficiency across different modes, with the transflective VA mode achieving wide viewing angles and improved optical effects.
Implementation Method 1
The liquid crystal molecules for a LCD device have orientation characteristics of arrangement resulting from their thin and long shape. An arrangement direction of the liquid crystal molecules can be controlled by applying an electrical field to them.
Implementation Method 2
The LCD device displays images using a variation of transmittance of the liquid crystal molecules by controlling magnitudes of the electric field.
Implementation Method 3
the electric field 50 between the pixel and common electrodes 12 and 24 is distorted by the pixel electrode rib 12a and the common electrode rib 24a such that first and second oblique electric field 50a and 50b are induced. Thus, the liquid crystal layer 30 has two domains
Implementation Method 4
The reflective electrode reflects outside light or artificial light.
Implementation Method 5
a transflective type LCD device having advantages of the transmissive type LCD device and the reflective type LCD device is suggested. The transflective type LCD device includes a transmissive area and a reflective area in the pixel region to convert between the transmissive mode and the reflective mode depending on the surroundings.
Data Source
AI summary
A liquid crystal display device comprises first and second substrates facing each other and including a plurality of pixel regions, each of the plurality of pixel regions including transmissive and reflective areas; a plurality of first electric field distorting units repeatedly arranged in the transmissive area, wherein each of the plurality of first electric field distorting units generates a first domain structure; a plurality of second electric field distorting units repeatedly arranged in the reflective area, wherein each of the plurality of second electric field distorting units generates a second domain structure having less domains than the first domain structure; and a liquid crystal layer interposed between the first and second substrates.