Liquid Crystal Optical Element for Thin Pattern Projection
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Solution Overview
Problem
Existing small-sized light irradiation devices face challenges in reducing thickness while maintaining effective optical pattern projection, due to complex configurations and large lens thickness, which hinders the miniaturization of mobile electronic devices.
Innovation Solution
A light irradiation device incorporating a liquid crystal optical element with an optically anisotropic layer featuring a liquid crystal alignment pattern where the orientation of the optical axis continuously changes rotationally, combined with a lens array and diffractive optical element, to refract and diverge light beams, reducing device thickness and enhancing projection capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a light guide with reflection surfaces arranged at 45° angles is used to reduce device thickness, then the device thickness is reduced, but the device configuration becomes complicated
Solution Approach 1:
The patent replaces the mechanical reflection system (multiple reflection surfaces at 45° angles) with an optical system using a liquid crystal optical element that controls light direction through optical anisotropy. This substitution simplifies the mechanical structure while achieving the same light guiding function, thereby reducing device complexity while maintaining reduced thickness.
Solution Approach 2:
The patent changes the optical parameters of the light guide by incorporating a liquid crystal optical element that modifies the refractive index and optical axis orientation. This allows control of light propagation direction through optical parameter adjustment rather than mechanical reflection geometry, simplifying the overall device configuration.
2Illumination intensity
If a thick lens is used to distribute light in different directions, then effective optical pattern projection is achieved, but the device thickness increases
Solution Approach 1:
The patent replaces the thick conventional lens with a liquid crystal optical element that achieves light distribution through optical anisotropy and controlled refraction. This substitution maintains effective optical pattern projection while dramatically reducing the thickness required for light distribution functionality.
Solution Approach 2:
The patent transitions from controlling light distribution primarily in the vertical dimension (through lens thickness) to controlling it through optical axis orientation in the lateral dimension. The liquid crystal optical element achieves directional light control through in-plane optical axis arrangement, enabling thin-profile design without sacrificing projection effectiveness.
3Manufacturing precision
If the liquid crystal optical element has regions with different period lengths in the liquid crystal alignment pattern, then beam divergence is reduced and projection resolution is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by creating regions with different period lengths in the liquid crystal alignment pattern at specific locations. This allows optimization of beam divergence and projection resolution in different areas of the optical element, achieving high manufacturing precision through spatially varying optical properties.
Solution Approach 2:
The patent utilizes the dynamic reconfigurability of liquid crystal materials to achieve different optical effects. The liquid crystal optical element can dynamically adjust its optical axis orientation and period structure, enabling precise beam control without requiring complex static manufacturing processes for each region.
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 results in a thinner light irradiation device capable of projecting optical patterns with improved resolution and coverage, simplifying the device configuration and reducing beam divergence, thus addressing the thickness and miniaturization challenges of mobile electronic devices.
Implementation Method 1
a liquid crystal optical element, in which the liquid crystal optical element has an optically anisotropic layer formed using a liquid crystal composition containing a liquid crystal compound, the optically anisotropic layer has a liquid crystal alignment pattern in which orientation of an optical axis derived from the liquid crystal compound continuously changes rotationally
Implementation Method 2
the liquid crystal optical element has an optically anisotropic layer formed using a liquid crystal composition containing a liquid crystal compound
Implementation Method 3
By duplicating the formed optical pattern in different directions using a diffractive optical element
Data Source
AI summary
An object of the present invention is to provide a light irradiation device which is thin and is capable of projecting an optical pattern, and a sensor which uses the light irradiation device. The object is achieved by a light irradiation device including a light emitting element which includes a plurality of light emitting units in a plane; and a liquid crystal optical element, in which the liquid crystal optical element has an optically anisotropic layer formed using a liquid crystal composition containing a liquid crystal compound, the optically anisotropic layer has a liquid crystal alignment pattern in which orientation of an optical axis derived from the liquid crystal compound continuously changes rotationally along at least one in-plane direction and has regions with different lengths of periods in a case where a length over which the orientation of the optical axis derived from the liquid crystal compound rotates by 180° in the plane is denoted by a single period.