Head-Up Display Optical Waveguide Alignment for Reduced Color Shift
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Solution Overview
Problem
Existing head-up displays face challenges in precisely aligning multiple optical fibers for different colors, leading to distortions and color shifts, which hinder the utilization of optical compensation options for varying windshield curvatures.
Innovation Solution
Introduce markings during the exposure process to create grating structures on optical fibers, allowing precise alignment through camera recognition and detection, ensuring that the markings align perfectly with the holograms, enabling accurate positioning of superimposed optical fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple optical fibers are aligned manually or using conventional methods, then the alignment process is simple, but the alignment precision is insufficient leading to distortions and color shifts
Solution Approach 1:
The patent introduces markings as intermediary elements that are written into the optical waveguides during the exposure process. These markings serve as reference features that mediate between the alignment system and the optical fibers, enabling precise alignment through camera detection of the markings' positions and orientations.
Solution Approach 2:
The markings are written into the optical waveguides during the exposure process itself, before the alignment and assembly steps. This preliminary action ensures that the reference features are already in place and precisely positioned within the waveguide structure, eliminating the need for subsequent marking or alignment adjustments.
2Measurement precision
If markings are illuminated to detect alignment patterns, then alignment detection is enabled, but the light beam path becomes complex requiring precise focal length coordination
Solution Approach 1:
The patent carefully selects and coordinates the focal lengths of the markings' lenses as a critical parameter. By optimizing the focal length values and their relationships, the system achieves precise alignment detection while managing the complexity of the optical path. The focal lengths are chosen so that light from a single point source forms focused spots at specific detection planes, enabling accurate position and orientation measurement.
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
Achieves precise alignment of optical fibers, allowing full utilization of optical compensation options for compensating windshield curvatures, reducing distortions and color shifts, and enhancing the display's optical performance.
Implementation Method 1
the markings have a lens function whose associated focal lengths are selected such that a correct pattern only appears during illumination if the distance between the individual optical waveguides also assumes a predetermined value
Implementation Method 2
the markings of the individual optical waveguides are grating structures or holograms which influence the light used during illumination
Data Source
Figure 1
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Figure 5~6
AI summary
The invention relates to a method for exactly aligning at least two holograms (52, 52R, 52G, 52B, 53, 53R, 53G, 53B) with respect to one another, said holograms being disposed in optical waveguides (5, 5R, 5G, 5B). The method includes: - writing (S1) a first hologram (51R, 52R, 53R) and a first marking (71R, 72R, 721R) in a first optical waveguide (5R), - writing (S2) a second hologram (51G, 52G, 53G) and a second marking (71G, 72G, 721G) in a second optical waveguide (5G), - positioning (S4) the first optical waveguide (5R) and the second optical waveguide (5G) with respect to one another, - illuminating (S5) the first marking (71R, 72R, 721R) and the second marking (71G, 72G, 721G), - detecting (S6) a pattern (M) occurring during the illumination (S5) after passing the first marking (71R, 72R, 721R) and the second marking (71G, 72G, 721D), - modifying (S7) the position of one of the optical waveguides (5R, 5G, 5B) until the detected pattern (M) corresponds to the target pattern.