Multilayer Optical Element for Asymmetric Oblique Light Shielding
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Solution Overview
Problem
Existing display devices suffer from light leakage and color distortion in oblique directions, leading to reduced contrast and asymmetric visibility when viewed from different angles, particularly in applications like in-vehicle displays.
Innovation Solution
An optical element comprising a specific configuration of polarizers and retardation layers with varying tilt angles and orientations, including a negative C plate, to create a vertically asymmetric light shielding region that curbs light leakage and color distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional optical elements are used to improve visibility, then front visibility is improved, but light leakage occurs in oblique directions and contrast is reduced
Solution Approach 1:
The patent implements vertical asymmetry in the light shielding characteristics by configuring multiple retardation layers with different tilt angle variations. The first and second retardation layers have tilt angles increasing from polarizer side toward negative C plate side, while the third and fourth retardation layers have tilt angles decreasing from polarizer side toward opposite retardation layer side. This asymmetric configuration creates different light shielding performance for upward and downward oblique directions, effectively reducing light leakage while maintaining front visibility.
Solution Approach 2:
The patent transitions from conventional single-layer or symmetric multi-layer configurations to a four-layer asymmetric structure with controlled tilt angle variations in each layer. By manipulating the tilt angle profiles across multiple layers (increasing in first two layers, decreasing in last two layers), the invention adds dimensional control over the light shielding characteristics in the vertical azimuthal direction, enabling suppression of oblique light leakage without compromising front visibility.
2Illumination intensity
If optical elements are added to improve visibility, then luminance is improved, but coloring occurs in oblique directions
Solution Approach 1:
The patent applies different tilt angle variation characteristics to different retardation layers to address specific optical issues at different locations in the vertical stack. The first and second retardation layers use increasing tilt angles from polarizer side toward negative C plate side to control one aspect of oblique light behavior, while the third and fourth retardation layers use decreasing tilt angles to control another aspect. This local differentiation in tilt angle profiles enables independent optimization of luminance and color characteristics in oblique directions.
Solution Approach 2:
The patent combines multiple retardation layers with distinct tilt angle characteristics and a negative C plate to create a composite optical structure. Each layer contributes different optical properties through its specific tilt angle variation pattern, and the combination of these layers with the negative C plate produces a synergistic effect that maintains accurate color reproduction in oblique directions while preserving high luminance.
3Ease of manufacture
If symmetric light shielding is used, then manufacturing is simplified, but asymmetric visibility is required for in-vehicle displays
Solution Approach 1:
The patent deliberately introduces vertical asymmetry into the optical element by configuring the tilt angle variations differently in the upper and lower halves of the multi-layer structure. The first and second retardation layers (upper half) have tilt angles increasing from polarizer side, while the third and fourth retardation layers (lower half) have tilt angles decreasing from polarizer side. This asymmetric configuration provides enhanced visibility and reduced light leakage specifically in the upward direction, which is particularly beneficial for in-vehicle display applications where drivers typically view the display from below.
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
Enhances light shielding in oblique directions, improves luminance and contrast, and achieves asymmetric visibility based on viewing angle, reducing unwanted light leakage and color issues.
Implementation Method 1
a first retardation layer including first anisotropic molecules... tilt angles of the first anisotropic molecules increase from the first polarizer side of the first retardation layer toward the negative C plate side
Implementation Method 2
a second retardation layer including second anisotropic molecules... tilt angles of the second anisotropic molecules increase from the second polarizer side of the second retardation layer toward the negative C plate side
Implementation Method 3
a third retardation layer including third anisotropic molecules... tilt angles of the third anisotropic molecules decrease from the second polarizer side of the third retardation layer toward the fourth retardation layer side
Implementation Method 4
a fourth retardation layer including fourth anisotropic molecules... tilt angles of the fourth anisotropic molecules decrease from the third polarizer side of the fourth retardation layer toward the third retardation layer side
Implementation Method 5
an absorption axis or a reflection axis of the first polarizer, an absorption axis or a reflection axis of the second polarizer, and an absorption axis or a reflection axis of the third polarizer are parallel to each other
Data Source
AI summary
An optical element includes a first polarizer, a first retardation layer including first anisotropic molecules, a negative C plate, a second retardation layer including second anisotropic molecules, a second polarizer, a third retardation layer including third anisotropic molecules, a fourth retardation layer including fourth anisotropic molecules, and a third polarizer. Tilt angles of the third anisotropic molecules decrease from the second polarizer side of the third retardation layer toward the fourth retardation layer side of the third retardation layer. Tilt angles of the fourth anisotropic molecules decrease from the third polarizer side of the fourth retardation layer toward the third retardation layer side of the fourth retardation layer. An angle formed by the slow axis of the third retardation layer and the slow axis of the fourth retardation layer is 10° or greater and 20° or smaller.