Diffractive Optical Element Viewing Angle Compensation
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Solution Overview
Problem
Conventional TN LCDs suffer from limited viewing angles, resulting in issues such as low contrast, gray level inversion, and color shift, especially when viewed obliquely, due to their twisted nematic structure and lack of effective compensation mechanisms.
Innovation Solution
Incorporating a diffractive optical element with a diffraction grating disposed between the polarizers and the liquid crystal layer, which diffracts light to improve image quality across a wider viewing angle range by converting the normal viewing image into a side viewing image, thereby enhancing brightness, chroma, and gamma curve consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a TN LCD structure is used, then the response speed is high and cost is low, but the viewing angle is limited and image quality deteriorates at oblique angles
Solution Approach 1:
The patent introduces a diffractive optical element that operates in the optical dimension to redirect light paths. By using diffraction gratings with specific periods and orientations, the system converts normally emitted light into obliquely directed light, effectively adding a dimensional transformation to the light propagation path without changing the underlying TN LCD structure.
Solution Approach 2:
The diffractive optical element serves as an intermediary component between the TN LCD and the viewer. This intermediate layer with periodic structures modifies the optical characteristics of transmitted light, enabling the TN LCD to achieve wide viewing angle performance while maintaining its original fast response characteristics.
2Adaptability or versatility
If compensation films are added to improve viewing angle, then image quality at oblique angles improves, but device complexity and cost increase
Solution Approach 1:
The diffractive optical element performs multiple functions simultaneously: it acts as a viewing angle compensator, a light guide, and an optical modifier. This single component replaces what would traditionally require multiple separate compensation films and optical layers, thereby reducing overall device complexity while achieving wide viewing angle performance.
Solution Approach 2:
The patent modifies optical parameters by introducing periodic structures with specific grating periods, depths, and orientations. By changing the physical parameters of the diffractive element, the system achieves different diffraction patterns that compensate for viewing angle dependencies without requiring complex multi-layer compensation film structures.
3Adaptability or versatility
If the diffractive optical element is optimized for wide viewing angle, then image quality uniformity improves, but light efficiency may be reduced
Solution Approach 1:
The diffractive optical element employs different grating structures in different regions or orientations to optimize performance for specific viewing directions. By localizing different diffraction characteristics to different areas, the system achieves uniform image quality across wide viewing angles while minimizing unnecessary diffraction that would reduce light efficiency.
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 significantly improves image quality uniformity across various viewing angles, increasing the half-height width of contrast and reducing gray level inversion and color shift, making the display more suitable for wide viewing angle applications while maintaining lower costs and higher response speed.
Implementation Method 1
The diffractive optical element is disposed in the lighting direction of the display to diffract the light constructing the first observable image to the second viewing angle range
Data Source
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AI summary
A display device is disclosed. The display device includes a display and a diffractive optical element (DOE). The display is used to show an image. When a user looks at the image within a first viewing angle range, he can see a first observed image, and when he looks at the image within a second viewing angle range, he can see a second observed image. The diffractive optical element is disposed in the lighting direction of the display to diffract the light constructing the first observed image to the second viewing angle range, thereby converting the first observed image into a third observed image and converting the second observed image into a fourth observed image at the same time.