Transmissive Reflective Subpixel Display for Bright Outdoor Visibility
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Solution Overview
Problem
Current liquid crystal display technologies, such as LCDs and AMOLEDs, face limitations in brightness and contrast when used outdoors in bright conditions due to inherent reflectivity and limited electrical energy storage, leading to washed-out images and reduced battery life, especially with high pixel densities.
Innovation Solution
A display system with transmissive and reflective subpixels that modulate light independently, allowing for optimized voltage control and reduced circuitry blockage, enabling improved brightness and contrast without the need for constant backlight usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If emissive displays (LCD/AMOLED) are used to provide readability in low to moderate light conditions, then visibility is improved, but battery life is reduced due to limited electrical energy storage and finite conversion efficiency
Solution Approach 1:
The display is segmented into transmissive subpixels (for backlight transmission) and reflective subpixels (for ambient light reflection), each with independent control. This allows the device to use reflective mode for low-power always-on display and transmissive mode for full brightness when needed, resolving the contradiction between brightness and energy consumption
Solution Approach 2:
The display dynamically switches between reflective and transmissive modes based on ambient light conditions and user interaction. In adequate lighting, reflective subpixels provide low-power display; in low light or for full brightness, transmissive subpixels with backlight are activated, optimizing the balance between illumination intensity and energy use
2Use of energy by moving object
If transflective displays are used to provide both reflective and transmissive portions, then energy efficiency is improved, but display contrast is reduced due to distorted liquid crystal regions from corrugated surfaces
Solution Approach 1:
Instead of using a corrugated surface that creates distorted regions, the display is segmented into separate transmissive and reflective subpixel regions with flat surfaces. Each subpixel type has uniform liquid crystal depth, eliminating distortion while maintaining energy efficiency through the transflective architecture
Solution Approach 2:
Different regions of the display have different optical properties: transmissive subpixels are optimized for backlight transmission with uniform liquid crystal depth, while reflective subpixels are optimized for ambient light reflection. This local optimization maintains high contrast in both modes without requiring corrugated surfaces
3Manufacturing precision
If very high pixel densities (greater than 300 ppi) are implemented, then display resolution is improved, but contrast is further reduced due to increased relative size of distorted regions
Solution Approach 1:
The display is segmented into separate transmissive and reflective subpixel regions, eliminating the need for corrugated surfaces that create distorted regions. This segmentation allows high pixel density to be achieved without the contrast-penalyting distortion effects that plague transflective displays
Solution Approach 2:
Each subpixel region (transmissive or reflective) has uniformly optimized liquid crystal depth and optical properties for its specific function. This local quality control ensures that even at very high pixel densities, each subpixel maintains optimal contrast without being affected by distorted regions from corrugation
4Illumination intensity
If constant backlight usage is employed to maintain display visibility, then visibility is improved, but battery life is reduced
Solution Approach 1:
The display dynamically adjusts its operational mode based on ambient light conditions. In adequate lighting, reflective subpixels provide visibility without backlight consumption. In low light conditions or when full brightness is needed, transmissive subpixels with backlight are activated. This dynamic adaptation resolves the contradiction between constant visibility and battery conservation
Solution Approach 2:
The reflective subpixels enable the display to serve itself by reflecting ambient light, eliminating the need for constant backlight power consumption. The display automatically adapts to environmental lighting conditions, providing visibility when needed without continuous energy expenditure
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
Enhances display visibility in bright outdoor conditions while conserving battery life by allowing the device to function as an always-on display in adequately lit environments without constant backlight usage, maintaining high pixel density and contrast.
Implementation Method 1
electric voltages are used to alter the configuration (e.g., the molecular long axis orientation) of the liquid crystals in the display to modulate the passage of light through the display
Implementation Method 2
In the reflective portion, light traverses the liquid crystal twice-once going in and once going out after reflection
Data Source
Figure 1~2
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AI summary
A device (100) includes a display (102, 800) that is suitable for use under widely ranging lighting conditions. The display includes separately operable transmissive light modulator subpixels (402, 404, 406, 502, 504, 506, 602, 604, 606, 702, 704, 706, 808, 810, 812, 1036, 1136, 1204, 1304, 1404, 1504, 1716, 1916) that can be provided in at least three colors to provide a full color display but also includes separately operable reflective light modulator subpixels (408, 508, 608, 708, 814, 1038, 1138, 1202, 1302, 1402, 1502, 1714, 1914) that provide basic readability when light levels are so high (e.g., bright summer day) that the image presented by the transmissive light modulators would be difficult to discern. The reflective light modulators may be provided with in-pixel memory (526) so as to reduce the energy cost of providing always-on functioning for displaying certain time sensitive information.