Electro-optical Device Circularly Polarized Light Control
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Solution Overview
Problem
Existing liquid crystal devices using blue phase materials face issues with increased driving voltage and contrast degradation due to excessive chiral agent deposition and temperature-induced wavelength shifts, which affect display characteristics.
Innovation Solution
An electro-optical device design that includes a polarizing device to prevent selective reflection of circularly polarized light, allowing it to pass through without being reflected by the electrooptic material layer, thereby reducing the need for excessive chiral agents and maintaining contrast across temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of additive chiral agent is increased to set the selectively reflected wavelengths to a shorter wavelength side, then the selectively reflected wavelengths are shifted to shorter wavelengths, but the chiral agent is deposited and the saturation voltage is shifted to a high voltage side
Solution Approach 1:
The patent changes the parameter of circularly polarized light rotation direction to match the helix turning direction of the liquid crystal material. By setting the light's rotation direction to be the same as the helix direction, selective reflection is prevented without requiring excessive chiral agent, thus avoiding deposition issues while maintaining wavelength control
2Quantity of substance
If the amount of additive chiral agent is increased to set the selectively reflected wavelengths to a shorter wavelength side, then the selectively reflected wavelengths are shifted to shorter wavelengths, but an electric field of a higher magnitude is required to drive the cholesteric blue phase
Solution Approach 1:
The patent changes the parameter of circularly polarized light rotation direction to match the helix turning direction of the liquid crystal material. This parameter change prevents selective reflection without requiring excessive chiral agent, thereby avoiding the shift of saturation voltage to high voltage side and maintaining lower driving voltage requirements
3Quantity of substance
If the selectively reflected wavelengths are set to a shorter wavelength side with respect to the visible light range, then the selectively reflected wavelengths may be shifted into the visible light range because of a change in temperature, but the contrast decreases
Solution Approach 1:
The patent changes the parameter of circularly polarized light rotation direction to match the helix turning direction of the liquid crystal material. This parameter change prevents selective reflection regardless of temperature-induced wavelength shifts, thereby maintaining stable contrast across temperature variations without requiring excessive chiral agent
Solution Approach 2:
The patent applies preliminary anti-action by pre-configuring the circularly polarized light rotation direction to match the helix turning direction before temperature changes occur. This pre-configured matching prevents selective reflection from occurring even when temperature shifts cause wavelength changes, thereby preemptively maintaining contrast stability
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 lowers the driving voltage and prevents contrast degradation by ensuring that the light entering the electrooptic material layer is not selectively reflected, regardless of temperature-induced wavelength shifts, thus improving display characteristics without excessive chiral agent deposition.
Implementation Method 1
An electro-optical device that uses electronic polarization due to Kerr effect is known. The Kerr effect is a phenomenon that, when an electric field is applied, exhibits optical anisotropy which has an axis in the direction of the electric field and of which the degree is proportional to the square of the magnitude of the electric field.
Implementation Method 2
The liquid crystal material that exhibits a blue phase selectively reflects (selective reflection) circularly polarized light that advances toward the liquid crystal layer and that has the same rotation direction as the turning direction of the helix of the liquid crystal material.
Implementation Method 3
Light that passes through the polarizing device is a second circularly polarized light that has a second rotation direction reverse to the first rotation direction of the first circularly polarized light.
Data Source
AI summary
An electro-optical device includes, a first substrate, a second substrate, an electrooptic material layer, an illuminating device, and a polarizing device. The electrooptic material layer is held between the first substrate and the second substrate. The illuminating device irradiates illumination light to an outer surface of the first substrate. The polarizing device is provided on the outer surface of the first substrate. The electrooptic material layer exhibits optical isotropy when no electric field is applied, and, when an electric field is applied, exhibits optical anisotropy corresponding to the magnitude of the electric field. The electrooptic material layer further has a characteristic to selectively reflect a first circularly polarized light having a first rotation direction. Light that passes through the polarizing device is a second circularly polarized light that has a second rotation direction reverse to the first rotation direction of the first circularly polarized light.