Blue Phase LCD Double-Sided Electric Field Design
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Solution Overview
Problem
Conventional liquid crystal display devices using polymer stabilized positive blue phase liquid crystals suffer from light leakage in the dark state due to incomplete optical isotropy, resulting in a low contrast ratio.
Innovation Solution
The implementation of a double-sided electrode design that generates both horizontal and vertical electric fields within the liquid crystal cell, where the horizontal electric field enhances light transmittance and the vertical electric field compensates for optical isotropy, reducing light leakage and improving contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If polymer stabilized positive blue phase liquid crystal is used to achieve wide temperature range and fast response, then response time is improved and temperature range is expanded, but optical isotropy is incomplete causing light leakage in dark state
Solution Approach 1:
The patent segments the electric field into two independent components: horizontal electric field (for switching control) and vertical electric field (for optical isotropy compensation). This is achieved by dividing the electrode structure into pixel electrodes and counter electrodes with specific patterns, allowing each electrode pair to independently control different aspects of liquid crystal behavior without interfering with each other
Solution Approach 2:
The patent introduces a vertical electric field dimension in addition to the conventional horizontal electric field. This dimensional addition allows simultaneous control of light transmittance (horizontal field) and optical isotropy (vertical field), resolving the contradiction between fast response and reduced light leakage by operating in multiple field dimensions
2Use of energy by moving object
If conventional single horizontal electric field is applied to drive the liquid crystal, then light transmittance control is achieved, but optical isotropy is not compensated resulting in low contrast ratio
Solution Approach 1:
The patent segments the electrode system into functionally distinct horizontal electrode pairs (for transmittance control) and vertical electrode pairs (for isotropy compensation). This segmentation allows independent optimization of each function without compromising the other, achieving both energy efficiency and high contrast ratio
Solution Approach 2:
The patent creates a multi-functional electrode system where each electrode pair can serve multiple purposes: the horizontal electrodes control light transmittance while the vertical electrodes compensate optical isotropy. This universal design allows a single device structure to simultaneously achieve multiple performance goals that were previously conflicting
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 effectively reduces light leakage in the dark state, increasing the contrast ratio from 23 to 302, and maintains the advantages of fast response time and wide operational temperature range of blue phase liquid crystals.
Implementation Method 1
The first pixel electrode and the first counter electrode provide a horizontal electric field parallel to the first substrate and the second substrate
Implementation Method 2
The second vertical electrode and the first vertical electrode have different electrical potentials thus form a vertical electric field perpendicular to the first substrate and the second substrate
Data Source
AI summary
A liquid crystal display device includes a first substrate, a second substrate, a first vertical electrode, a second vertical electrode, a first pixel electrode, a first counter electrode, and a liquid crystal layer. The second substrate is disposed to be opposite to the first substrate, the liquid crystal layer is interposed between the first and second substrates. The liquid crystal layer includes polymer stabilized positive blue phase liquid crystal. The first vertical electrode is at an inner side of the first substrate, and faces the second substrate. The second vertical electrode is at an inner side surface of the second substrate and faces the first vertical electrode. The second vertical electrode and the first vertical electrode have different electrical potentials thus form a vertical electric field perpendicular to the first substrate and the second substrate. The first pixel electrode is at the inner side of the first substrate and faces the second substrate. The first counter electrode is at an inner side of the first substrate. The first pixel electrode and the first counter electrode have different electrical potentials. The first pixel electrode and the first counter electrode provide a horizontal electric field parallel to the first substrate and the second substrate.