Head-Up Display Prism Layout for Low Distortion and Stray Light
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Solution Overview
Problem
Existing head-up displays face challenges in size reduction and effectively reducing stray light generated by external light, leading to distortion and aberration issues.
Innovation Solution
The implementation of a head-up display with a projection optical system that includes a free-form surface prism with inclined incident and emitting surfaces, which refracts and reflects light to correct aberration and reduce stray light, while integrating two mirrors to form an intermediate image without separate mirror elements, thereby shortening the optical system length and achieving size reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional optical system with separate mirrors and lenses is used, then the optical path can be established, but the system size becomes large and complex
Solution Approach 1:
The patent combines multiple optical elements (prism, mirrors, lenses) into an integrated optical system where the free-form surface prism serves as both a light redirecting element and an aberration correction element, eliminating the need for separate correction lenses and reducing overall system complexity
Solution Approach 2:
The patent employs free-form surfaces with complex curvatures on the prism and optical elements to correct aberrations, replacing what would traditionally require multiple separate spherical or cylindrical elements, thereby reducing system size while maintaining optical performance
2Reliability
If traditional optical elements are used without inclination, then the structure is simpler, but stray light from external light causes distortion and aberration
Solution Approach 1:
The patent introduces asymmetric inclination angles for the incident surface and emitting surface of the free-form surface prism, creating an asymmetric optical path that redirects external stray light away from the observer's viewpoint while maintaining the desired image projection, thereby improving image quality without requiring additional light blocking elements
3Length of moving object
If the optical system length is reduced, then the device becomes more compact, but distortion and aberration increase
Solution Approach 1:
The patent uses free-form surfaces with specifically designed curvatures on the prism and optical elements to correct aberrations within a compact configuration, allowing the system to maintain high image precision despite reduced optical path length
Solution Approach 2:
The patent optimizes various optical parameters including inclination angles, curvature radii, and surface profiles of the free-form surfaces to achieve the best balance between compact size and image quality, demonstrating that precise parameter control can maintain precision in reduced-size systems
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 results in a head-up display with reduced distortion, improved optical characteristics, and effective reduction of stray light, allowing for a more compact design while maintaining clear virtual image projection.
Implementation Method 1
a free-form surface prism 123 with sequentially disposed incident surface 123a, reflection surface 123b, and emitting surface 123c in a light path from the display device 110, wherein at least the emitting surface 123c is inclined with respect to a reference light Lc
Implementation Method 2
a free-form surface prism 123 with sequentially disposed incident surface 123a, reflection surface 123b, and emitting surface 123c in a light path from the display device 110
Data Source
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AI summary
The present disclosure provides a head-up display presenting a virtual image with less distortion, and achieving size reduction and effectively reducing stray light generated by external light. A head-up display of the present disclosure is a head-up display that projects a display image on a transparent reflecting member to present a visually recognizable virtual image. The head-up display includes: a display device that displays the display image; and a projection optical system that projects the display image displayed on the display device as a virtual image for an observer. On an assumption that light reaching a center of a viewpoint region of the observer and corresponding to a center of the virtual image is reference light, the projection optical system includes a prism element that has an incident surface, a reflection surface, and an emitting surface sequentially in an optical path from the display device. At least either the incident surface or the emitting surface is inclined to the reference light.