Switchable Coupling-In Hologram for Head-Up Display Contrast
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Solution Overview
Problem
Current head-up displays based on optical fibers suffer from suboptimal contrast behavior due to uncontrolled coupling and decoupling of scattered light, which affects the quality of the virtual image displayed.
Innovation Solution
The implementation of a switchable coupling-in hologram combined with an electrode array allows precise control over light coupling into the optical waveguide, minimizing scattered light by defining inactive areas where no light is coupled, thereby improving contrast behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a switchable coupling-in hologram with electrode array is implemented to control light coupling, then contrast behavior is improved, but device complexity increases
Solution Approach 1:
The electrode array is segmented into multiple independently controllable electrodes that can selectively couple or decouple light in different spatial regions. This segmentation allows precise control over scattered light coupling while maintaining the ability to display image content, resolving the contradiction between improving contrast behavior and increasing device complexity.
Solution Approach 2:
The coupling-in hologram is made dynamically switchable through the electrode array, allowing real-time adjustment of light coupling based on whether scattered light or image content should be coupled. This dynamic control enables the system to adapt its behavior to optimize contrast while managing complexity through intelligent control strategies.
2Illumination intensity
If scattered light is minimized by defining inactive areas, then contrast behavior is improved, but light coupling efficiency for image content may be reduced
Solution Approach 1:
Different regions of the coupling-in hologram are assigned different functional qualities: active areas are optimized for coupling image content while inactive areas are optimized for minimizing scattered light coupling. This local differentiation allows the system to improve contrast in specific regions without compromising overall light coupling efficiency for image content.
Solution Approach 2:
The system maintains continuous useful action by dynamically switching between coupling and decoupling modes across different spatial regions and time periods. Active areas continuously couple image content while inactive areas continuously reject scattered light, ensuring both contrast improvement and maintained coupling efficiency through coordinated operation.
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 solution enhances the contrast behavior of head-up displays, particularly beneficial in environments requiring high contrast, such as motor vehicles, by reducing unwanted light coupling and maintaining image quality.
Implementation Method 1
The light coupled into the optical fiber, which carries the image information, undergoes total internal reflection at its interfaces and is thus guided within the optical fiber
Implementation Method 2
a first light-incident-side diffraction grating that diffracts incident light to cause the diffracted light to enter the optical waveguide
Implementation Method 3
A typical application is the area-wide switching on and off of the liquid crystal layer to synchronize the coupling in of multiple colors, corresponding to a sequentially operating light source
Implementation Method 4
An interference pattern is then generated in the cell by superimposing two laser beams. In the bright areas of the interference pattern, the monomers polymerize faster than in the dark areas
Implementation Method 5
An interference pattern is then generated in the cell by superimposing two laser beams
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to an optical waveguide (5) for a display device and to a method for controlling an optical waveguide of this type. The optical waveguide (5) has a switchable in-coupling hologram (53) and an electrode for switching the switchable in-coupling hologram (53). The electrode is designed as an electrode array (70) having a pixel matrix (71). The pixels (72) of the pixel matrix (71) can be switched individually. For this purpose, the pixels (72) can be connected to a voltage source (73). The pixels (72) are controlled by a control unit (74).