Illumination Device Phase Difference Layers Luminance Uniformity
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Solution Overview
Problem
Existing illumination devices for liquid crystal display devices, such as head-up displays, face challenges in achieving uniform luminance, which affects image quality and requires additional polarizers for linearly polarized light.
Innovation Solution
The illumination device incorporates a light source, first and second liquid crystal elements, phase difference layers, and a diffusion layer to diffract and convert circularly polarized light into linearly polarized light with a uniform polarization direction, eliminating the need for a polarizer and enhancing luminance uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional illumination devices use simple light sources without phase difference layers, then the device structure is simple, but the luminance uniformity is poor and additional polarizers are required
Solution Approach 1:
The illumination device is divided into multiple functional layers: first liquid crystal element, first phase difference layer, second liquid crystal element, second phase difference layer, and diffusion layer. Each layer performs a specific function in converting unpolarized light to uniformly polarized light, resolving the contradiction by achieving high luminance uniformity through structured segmentation rather than simple components
Solution Approach 2:
Phase difference layers are introduced as intermediary components between the light source and the liquid crystal display panel. These intermediary layers convert circularly polarized light to linearly polarized light with uniform polarization direction, eliminating the need for additional polarizers while achieving uniform luminance distribution
2Ease of operation
If additional polarizers are added to achieve linearly polarized light, then the polarization direction is controlled, but the device complexity increases and luminance uniformity deteriorates
Solution Approach 1:
The illumination device uses liquid crystal elements with specific alignment directions that automatically convert incident light into circularly polarized light, which is then converted to uniformly polarized light by the phase difference layers. This self-service mechanism eliminates the need for additional polarizers while maintaining polarization control, reducing device complexity
Solution Approach 2:
The patent changes the alignment directions of liquid crystal molecules in different regions (first region aligned in first direction, second region aligned in second direction) to control the polarization state of light. By changing alignment parameters rather than adding components, the device achieves polarization control with reduced complexity
3Ease of manufacture
If the alignment direction of liquid crystal molecules is fixed in one direction, then the manufacturing process is simple, but the polarization uniformity across different regions is poor
Solution Approach 1:
Different regions of the liquid crystal elements have different alignment directions: the first liquid crystal element has molecules aligned in a first direction, while the second liquid crystal element has molecules aligned in a second direction. This local quality differentiation ensures that each region contributes to uniform polarization, achieving high polarization uniformity while maintaining manufacturing simplicity through standardized alignment processes
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 configuration generates illumination light with a uniform polarization direction, reducing non-uniformity in luminance and allowing for efficient illumination of liquid crystal panels without additional polarizers, thereby improving image quality.
Implementation Method 1
the first liquid crystal element diffracts first circularly polarized light out of emitted light from the light source toward the first region, and diffracts second circularly polarized light rotating reversely to the first circularly polarized light toward the second region
Implementation Method 2
in the first region, the second liquid crystal element converts first circularly polarized light into second circularly polarized light and diffracts the second circularly polarized light toward the first phase difference layer, and in the second region, the second liquid crystal element converts second circularly polarized light into first circularly polarized light and diffracts the first circularly polarized light toward the second phase difference layer
Implementation Method 3
the first phase difference layer converts second circularly polarized light into linearly polarized light, the second phase difference layer converts first circularly polarized light into linearly polarized light
Implementation Method 4
a diffusion layer opposed to the first phase difference layer and the second phase difference layer
Data Source
AI summary
According to one embodiment, an illumination device includes a first liquid crystal element opposed to a light emitting region, a second liquid crystal element including a first main surface and a second main surface, a first phase difference layer disposed on the second main surface, a second phase difference layer disposed on the second main surface and adjacent to the first phase difference layer, and a diffusion layer opposed to the first phase difference layer and the second phase difference layer. Each of the first liquid crystal element and the second liquid crystal element has a plurality of liquid crystal molecules, and is cured in a state in which an alignment direction of the liquid crystal molecules has continuously changed in plane.