Transflective LCD Pixel Segmentation for Bright Environment Contrast
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Solution Overview
Problem
Transflective liquid crystal display devices face challenges in maintaining high image quality in display mode while switching to mirror mode, particularly in bright environments, due to issues with contrast and visibility, and suffer from lower saturation when displaying colors.
Innovation Solution
A liquid crystal display device with a transmission section and a mirror section in each pixel, controlled by a control unit, allowing independent switching between image display and black display states, and mirror and non-mirror states, respectively, to ensure high image quality and practicality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transflective liquid crystal display device uses a single pixel structure for both transmission and reflection functions, then the device can switch between display mode and mirror mode, but the image quality and contrast in display mode deteriorate in bright environments
Solution Approach 1:
The patent divides each pixel into two independent sub-pixels: a transmission sub-pixel for displaying images and a reflection sub-pixel for mirror functionality. This segmentation allows each sub-pixel to be optimized for its specific function, resolving the contradiction between versatility and image quality in bright environments.
Solution Approach 2:
The transmission sub-pixel and reflection sub-pixel are assigned different functional properties within the same pixel structure. The transmission sub-pixel uses coloring layers and liquid crystal alignment for image display, while the reflection sub-pixel uses reflective layers for mirror mode, allowing each region to have the quality needed for its specific function.
2Quantity of substance
If the device displays colors using coloring layers in transmission mode, then color saturation is achieved, but the reflected light in mirror mode reduces color saturation
Solution Approach 1:
By separating the pixel into transmission and reflection sub-pixels, the coloring layers are confined to only the transmission sub-pixel. This prevents reflected light from passing through coloring layers and reducing color saturation, while maintaining full color saturation in transmission mode.
Solution Approach 2:
The coloring layers are extracted from the reflection path by placing them only in the transmission sub-pixel. This removes the harmful effect of reflected light interacting with coloring layers, preserving color saturation when the device is used in mirror mode.
3Illumination intensity
If the liquid crystal layer is oriented in twisted alignment for display mode, then light transmission is achieved, but the contrast ratio decreases in bright environments
Solution Approach 1:
The liquid crystal layer is segmented into two regions with different orientations: the transmission sub-pixel uses twisted alignment for light transmission, while the reflection sub-pixel uses vertical alignment to block light. This segmentation allows the transmission sub-pixel to maintain good contrast ratio by preventing reflected light from reaching the viewer.
Solution Approach 2:
Different liquid crystal alignment characteristics are assigned to different sub-pixels. The transmission sub-pixel has twisted alignment optimized for light transmission, while the reflection sub-pixel has vertical alignment optimized for blocking light, allowing each region to have the local quality needed for its function.
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 enables high visibility and image quality in display mode, even in bright environments, and allows for a seamless transition to mirror mode without degrading image quality, while maintaining the ability to use the device as a mirror, thus enhancing both functionality and aesthetics.
Implementation Method 1
When no voltage is applied between common electrode 942 and electrode 944, liquid crystal layer 943 is oriented in twisted alignment where liquid crystal molecules sequentially twist by 90 degrees between substrates 930 and 950, causing the direction of linearly polarized light, which is transmitted through liquid crystal layer 943, to rotate by 90 degrees.
Implementation Method 2
In the mirror mode, external light incident on the liquid crystal display device from above polarizer plate 910 is reflected by reflector plate 945, and the reflected light is emitted upward from polarizer plate 910.
Implementation Method 3
Coloring layer 941a is a layer which colors light irradiated from back light 970 in one of red (R), green (G), and blue (B) by allowing the light to be transmitted through coloring layer 941a upward from blow.
Data Source
AI summary
A liquid crystal display device comprises a liquid crystal panel including sub-pixels and a back light for irradiating light to the back surface of liquid crystal panel. A transmission sub-pixel can be switched into an image display state which can allow irradiated light to exit, and a black display state which does not allow irradiated light to exit. A mirror sub-pixel can be switched between a mirror state which can allow reflected light to exit and a non-mirror state which does not allow reflected light to exit, independently of the transmission sub-pixel. A control unit places each transmission sub-pixel into the image display state or black display state, and places each mirror sub-pixel into the mirror state or non-mirror state.