Backlight Unit Uniformity Changing Element Banding Reduction
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Solution Overview
Problem
Holographic display systems face image quality deterioration due to banding patterns caused by light emitted from the light guide plate in backlight units, which affects the coherence and resolution of the displayed three-dimensional images.
Innovation Solution
A backlight unit incorporating a uniformity changing element, such as a birefringent material or a liquid crystal layer, that adjusts light paths and refractive indices in response to electrical signals, combined with a polarization conversion element to ensure uniform light output and reduce banding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a light guide plate is used to maintain light coherence in a holographic display, then the coherence of light is improved, but banding patterns are generated that deteriorate image quality
Solution Approach 1:
The patent applies local quality by varying the thickness of the light guide plate across different regions. The thickness is non-uniform, with different portions having different thickness values, which creates spatially varying optical path differences that randomize the interference patterns and eliminate banding while preserving overall light coherence for holographic display
Solution Approach 2:
The patent changes the physical parameter of the light guide plate thickness to resolve the banding issue. By adjusting the thickness parameter across different regions of the light guide plate, the optical path length is modified, which changes the interference conditions and eliminates the harmful banding patterns while maintaining the necessary light coherence
2Stability of the object's composition
If a grating is used to maintain light coherence, then the coherence is improved, but the device complexity increases
Solution Approach 1:
The patent extracts and removes the separate grating component from the optical system. Instead of using a dedicated grating structure to create interference patterns, the invention integrates the interference-generating function directly into the light guide plate itself through thickness variations, thereby eliminating the need for a separate grating and reducing device complexity
Solution Approach 2:
The patent merges the functions of the light guide plate and the grating into a single integrated component. The light guide plate simultaneously performs light guidance and interference pattern generation through its non-uniform thickness profile, combining multiple optical functions into one element and simplifying the overall device structure
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 effectively minimizes image banding, enhancing the coherence and uniformity of light output, thereby improving the overall quality of three-dimensional images in holographic displays.
Implementation Method 1
A backlight unit is provided, which includes a light guide plate and a uniformity changing element. The uniformity changing element may comprise a birefringent material.
Implementation Method 2
The uniformity changing element may comprise: at least one liquid crystal layer; first electrodes spaced apart from each other and arranged on a first side of the at least one liquid crystal layer; and second electrodes arranged on a second side of the at least one liquid crystal layer and respectively facing the first electrodes, wherein the at least one liquid crystal layer is between the first electrodes and the second electrodes, and wherein the liquid crystal layer may comprise liquid crystals whose refractive index changes according to an electrical signal applied to the corresponding first and second electrodes
Implementation Method 3
the light emitted from the light guide plate may cause a banding pattern
Implementation Method 4
a light guide plate and a uniformity changing element configured to change the uniformity of light incident from the light guide plate
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A backlight unit and a holographic display apparatus including the same are provided. The backlight unit includes a light guide plate and a uniformity changing element. The uniformity changing element has a light-incident surface and a light-exiting surface facing the light-incident surface, and the uniformity changing element receives the light output from the light guide plate through the light-incident surface, changes uniformity of the received light from the light guide plate and outputs the received light with the change in the uniformity of the received light through the light-exiting surface.