Transflective LCD Dichroic Substrates Bright Light Color Saturation
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Solution Overview
Problem
Transflective LCD panels face challenges in maintaining optimal optical properties under varying ambient light conditions, with de-saturated colors in bright light due to the dominance of reflective sub-pixel colors, and existing solutions do not effectively address this issue.
Innovation Solution
The use of dichroic color substrates that act as both filters and mirrors, depending on ambient light levels, and a pixel array structure with primary and secondary color sub-pixels, allowing for dynamic control of backlight and color production to enhance color saturation and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the reflective portion of the sub-pixel is used in bright ambient light conditions, then the display is visible, but the color produced is de-saturated and optical properties are diminished
Solution Approach 1:
Each sub-pixel is divided into two distinct regions: a reflective portion with a mirror for visibility in bright ambient light, and a transmissive portion with a color filter for producing saturated colors. This segmentation allows each region to optimize its function independently, resolving the contradiction between visibility and color saturation.
Solution Approach 2:
Different portions of the sub-pixel are assigned different optical properties: the reflective portion uses a mirror with high reflectivity for ambient light conditions, while the transmissive portion uses a color filter with specific spectral transmission characteristics for saturated color production. This local differentiation of properties enables the display to maintain both visibility and color quality.
2Manufacturing precision
If the transmissive portion of the sub-pixel is used, then fully saturated color is produced, but visibility is reduced in bright ambient light conditions
Solution Approach 1:
The sub-pixel is segmented into transmissive and reflective portions, allowing the transmissive portion to specialize in color saturation while the reflective portion handles visibility in bright conditions. This functional segmentation resolves the trade-off between color quality and visibility.
Solution Approach 2:
The sub-pixel structure is designed to perform multiple functions: the reflective portion provides visibility in bright ambient light, while the transmissive portion produces saturated colors. Together, they create a multi-functional sub-pixel that adapts to different viewing conditions, maintaining both visibility and color quality.
3Manufacturing precision
If an additional color-less sub-pixel is added to increase optical properties, then color saturation improves, but device complexity increases
Solution Approach 1:
The patent merges the reflective and transmissive functions within the existing sub-pixel structure by creating distinct portions rather than adding separate sub-pixels. This integration achieves improved color saturation and optical properties without increasing device complexity, as the dual-function sub-pixel replaces what would otherwise require additional components.
Solution Approach 2:
The sub-pixel is designed as a multi-functional element that combines both reflective and transmissive capabilities in a single structure. This universal design eliminates the need for additional color-less sub-pixels, maintaining device simplicity while achieving improved optical properties through the coordinated action of its dual portions.
4Manufacturing precision
If dichroic color substrates are used to act as both filters and mirrors, then color accuracy improves, but manufacturing complexity increases
Solution Approach 1:
The color substrate is designed with local quality variations: certain regions are configured as dichroic filters with specific transmission properties, while other regions are configured as mirrors with specific reflection properties. This localized differentiation enables precise color accuracy control without requiring complex manufacturing across the entire substrate.
Solution Approach 2:
The patent utilizes parameter changes in the optical properties of the color substrate to achieve dual functionality. By adjusting the spectral transmission and reflection parameters of different portions of the substrate, the design achieves both filter and mirror functions with standard manufacturing techniques, avoiding excessive complexity while maintaining color accuracy.
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 solution enables improved color saturation and accuracy across different lighting conditions by dynamically adjusting the LCD's operation to balance reflective and transmissive modes, resulting in better optical properties and reduced color inversion.
Implementation Method 1
a first liquid crystal layer comprising a first plurality of liquid crystal cells arranged in an array pattern, each liquid crystal cell having a twist angle of about 90 degrees
Implementation Method 2
a first color substrate associated with the first liquid crystal layer, the first color substrate comprising a first array of color filter elements arranged in correspondence to the array of sub-pixels
Implementation Method 3
a mirror arranged between the second color substrate and the second liquid crystal layer
Data Source
Figure 1
Figure 2a~2b
Figure 3~4
AI summary
A pixel of a transflective liquid crystal display panel having a controllable backlight comprises an array of sub-pixels and a color substrate with an array of colors corresponding to the array of sub-pixels, the array of colors comprising transmissive colors and reflective colors. The color substrate transmits at least one wavelength of light corresponding to the transmissive colors in the array of colors when the controllable backlight emits a first predetermined light level and, from substantially the same area in the color substrate, reflects at least one wavelength of light corresponding to the reflective colors in the array of colors when the controllable backlight emits a second predetermined light level. The transmissive colors may be primary or secondary colors, and the reflective colors may be primary or secondary colors. The primary colors may form the top row of the array of sub-pixels and the secondary colors may form the bottom row of the array of sub-pixels, or at least one of the primary colors and at least one of the secondary colors may form the top row of the array of sub-pixels, and at least one of the primary colors and at least one of the secondary colors may form the bottom row of the array of sub-pixels.