Transparent Display Device Using Cholesteric Liquid Crystal and Electrochromic Layer
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Solution Overview
Problem
The development of transparent display devices that can both transmit light and output full colors by reflecting various wavelengths is challenging due to the difficulty in implementing such devices that show objects behind them while maintaining color accuracy.
Innovation Solution
A display device structure comprising a first substrate, a second substrate, a third substrate, a color display layer with cholesteric liquid crystal, and a color conversion layer, where the cholesteric liquid crystal is divided into cells displaying primary colors, and the color conversion layer is made of electrochromic materials or electrophoretic displays, allowing for electric field control to achieve transparent, black, or ash color states, preventing parallax and enabling light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transparent display device uses traditional display technologies, then it can display colors by reflecting various wavelengths, but it cannot effectively transmit light to show objects behind it
Solution Approach 1:
The display device is divided into multiple functional layers including a first substrate, color display layer, third substrate, color conversion layer, and second substrate. Each layer performs a specific function: the color display layer (with cholesteric liquid crystal) handles color reflection, while the color conversion layer (with electrochromic or electrophoretic materials) controls light transmission. This segmentation allows the device to simultaneously achieve both color display and light transmission capabilities that cannot be achieved with traditional single-layer display structures.
Solution Approach 2:
The patent employs composite material structures where cholesteric liquid crystal is combined with electrochromic or electrophoretic materials in different layers. The cholesteric liquid crystal provides selective wavelength reflection for color display, while the electrochromic/electrophoretic materials in the color conversion layer provide transparent, black, or ash color states for light control. This composite approach enables the device to overcome the limitations of traditional single-material display technologies.
2Strength
If the third substrate is made thick to provide structural support, then mechanical strength is improved, but parallax occurs and display quality deteriorates
Solution Approach 1:
The patent specifies that the third substrate thickness should be equal to or less than about 20% of the width of the color display layer or color conversion layer of one pixel. By controlling the thickness parameter within this range, the device maintains sufficient mechanical strength while minimizing parallax effects. This parameter optimization allows the thin third substrate to provide adequate structural support without compromising display quality, resolving the contradiction between strength and precision.
3Adaptability or versatility
If electrochromic or electrophoretic materials are used in the color conversion layer, then light transmission and color state control are improved, but device complexity increases
Solution Approach 1:
The color conversion layer uses electrochromic or electrophoretic materials that can display multiple states (transparent, black, and ash color) within a single layer structure. This multi-functional material approach allows the layer to perform both light transmission control and color state adjustment without requiring separate layers for each function. The electrochromic/electrophoretic materials respond to electrical signals to switch between different optical states, providing versatility while maintaining relatively simple device architecture.
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 allows for the simultaneous display of all colors and transmission of light, preventing parallax and improving display quality by using cholesteric liquid crystals and electrochromic or electrophoretic materials to control color states, effectively addressing the challenges of traditional transparent display devices.
Implementation Method 1
a color display layer formed between the first substrate and the third substrate, and including a cholesteric liquid crystal
Implementation Method 2
outputting full colors by reflecting various wavelength
Implementation Method 3
the color conversion layer may include one of an electrochromic organic material, an electrochromic inorganic material
Implementation Method 4
a reverse emulsion based on an electrophoretic display
Data Source
AI summary
A display device includes; a first substrate, a second substrate disposed substantially opposite to the first substrate, a third substrate disposed between the first substrate and the second substrate, a color display layer disposed between the first substrate and the third substrate, the color display layer comprising a cholesteric liquid crystal, a first electrode and a second electrode electrically connected to the color display layer, a color conversion layer disposed between the third substrate and the second substrate, and a third electrode and a fourth electrode electrically connected to the color conversion layer.