Transparent Display Unit Using H-PDLC Layer
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Solution Overview
Problem
Existing transparent display units suffer from reduced transmittance due to the presence of polarization sheets, which hinder the visibility of both displayed information and objects behind the display when no voltage is applied.
Innovation Solution
A transparent display unit is designed with an upper and lower substrate, each containing a transparent electrode and alignment film, and a colorful holographic polymer dispersed liquid crystal (H-PDLC) layer in between, where the alignment films control the orientation of negative liquid crystals to match or mismatch refractive indices with polymers, enabling a transparent state without polarization sheets and allowing for voltage-controlled color display and grey scale adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polarization sheets are used to control light polarization in transparent display units, then display visibility is improved, but transmittance is greatly decreased
Solution Approach 1:
The patent removes the polarization sheets from the display structure entirely. Instead of using polarization sheets to control light, the invention uses H-PDLC layers that can switch between transparent and reflective states based on voltage, eliminating the need for polarization filtering and thereby improving overall transmittance while maintaining display visibility.
Solution Approach 2:
The patent changes the operating parameter from polarization control to voltage-controlled refractive index modulation. By applying voltage to the H-PDLC layer, the refractive index changes, switching the layer between transparent (low voltage) and reflective (high voltage) states, which replaces the polarization-based control mechanism and improves transmittance.
2Adaptability or versatility
If liquid crystal molecules are used to change polarization direction to form grey scales, then display control is improved, but transmittance is greatly decreased
Solution Approach 1:
The patent uses voltage-controlled refractive index changes in H-PDLC layers to achieve grey scale control instead of polarization rotation. By varying the voltage applied to the H-PDLC layer, the refractive index is modulated, controlling the amount of light reflected or transmitted, thereby achieving grey scales without the transmittance loss associated with polarization control.
Solution Approach 2:
The patent employs holographic polymer dispersed liquid crystal (H-PDLC) composite material that combines polymers, liquid crystals, and dichroic dyes. This composite material enables voltage-controlled switching between transparent and reflective states with grey scale modulation, replacing the polarization-based liquid crystal display mechanism and improving overall transmittance.
3Reliability
If polarization sheets are incorporated in the display structure, then display function is achieved, but device complexity increases
Solution Approach 1:
The patent eliminates the polarization sheets from the display structure, reducing the number of components. The display function is maintained through voltage-controlled H-PDLC layers that can switch between transparent and reflective states, simplifying the overall device structure while preserving display functionality.
Solution Approach 2:
The H-PDLC layer serves multiple functions simultaneously: it acts as the display medium, the light control element, and the grey scale generator. By combining these functions into a single voltage-controlled layer, the patent reduces structural complexity compared to separate polarization sheets and liquid crystal alignment layers.
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 design enhances transmittance and allows for clear visibility of both displayed information and objects behind the display, improving the display's performance by eliminating the need for polarization sheets and enabling effective grey scale and color control through voltage manipulation.
Implementation Method 1
the alignment films control the orientation of negative liquid crystals to match or mismatch refractive indices with polymers
Implementation Method 2
make the refractive index of the negative liquid crystal match with the refractive index of the polymers
Implementation Method 3
when the transmissive type colorful H-PDLC is applied with a voltage, the negative liquid crystal contained in the transmissive type colorful H-PDLC is parallel to the surface of the upper substrate, such that the refractive index of the negative liquid crystal does not match with the refractive index of the first polymers so as to cause diffraction of the incident light
Implementation Method 4
the colorful H-PDLC layer comprises dichroic dye, negative liquid crystal and polymers
Data Source
AI summary
An embodiment of the present invention discloses a transparent display unit with improved transmittance. The transparent display unit comprises: an upper substrate comprising an upper transparent electrode and an upper alignment film in sequence from top to bottom; a lower substrate comprising a lower transparent electrode and a lower alignment film in sequence from bottom to top; and at least a colorful holographic polymer dispersed liquid crystal (H-PDLC) layer located between the upper substrate and the lower substrate.