Head-Up Display Optics for Compact Stray-Light Suppression
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Solution Overview
Problem
Existing head-up displays are large in size and susceptible to stray light interference from outside sources.
Innovation Solution
A head-up display configuration with a projection optical system that includes a first lens inclined with respect to a reference beam, a first optical element to diffuse light, and a telephoto arrangement of lenses to reduce size and inhibit stray light, using free-form surface lenses to correct distortions and adjust optical path lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional head-up display configuration is used, then the display can project images on the windshield, but the device becomes large in size
Solution Approach 1:
The first lens is inclined with respect to the reference beam, creating an asymmetric optical path that redirects stray light away from the observer's viewpoint. This asymmetric configuration allows the lens to serve dual functions: condensing useful light while deflecting harmful stray light, thereby reducing the overall device size without compromising reliability
Solution Approach 2:
The first optical element acts as an intermediary between the first lens and the observer, specifically designed to diffuse stray light. This intermediate component mediates the interaction between condensed light and the observer's eye, allowing the system to maintain a compact form factor while effectively blocking stray light interference
2Object-affected harmful factors
If the first lens is inclined with respect to the reference beam, then stray light is inhibited, but the optical path becomes more complex
Solution Approach 1:
Only the first lens is inclined with respect to the reference beam, while other optical elements maintain their conventional orientations. This localized asymmetry approach inhibits stray light through the inclined lens without requiring complex reconfiguration of the entire optical path, thereby managing device complexity effectively
Solution Approach 2:
The inclination of the first lens introduces a dimensional change in the optical path arrangement, allowing stray light inhibition through spatial reconfiguration rather than through complex multi-element designs. This dimensional approach simplifies the overall optical complexity while achieving the desired stray light rejection
3Manufacturing precision
If free-form surface lenses are used, then image distortion is corrected, but manufacturing difficulty increases
Solution Approach 1:
The free-form surface lens is designed with specific functional zones: one region for condensing light and another region for deflecting stray light. This segmentation of functional areas within a single lens element allows for optimized distortion correction in critical areas while simplifying manufacturing in less critical regions, balancing manufacturing precision with ease of manufacture
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 configuration provides a smaller head-up display that effectively reduces stray light interference while maintaining clear, undistorted virtual images for the observer.
Implementation Method 1
a first lens configured to condense light
Implementation Method 2
a first optical element configured to diffuse light
Implementation Method 3
The first lens is inclined with respect to a reference beam which is defined as a beam reaching a center of a viewpoint region of the observer
Data Source
AI summary
A head-up display is configured to project an image on a transparent reflection member to cause an observer to visually recognize a virtual image, and includes a display device configured to display the image, and a projection optical system configured to project the image displayed by the display device as the virtual image for the observer. The projection optical system is configured to form an image as an intermediate image, and includes a first lens configured to condense light, and a first optical element configured to diffuse light. The first lens and the first optical element are disposed in this order along an optical path from the display device. The first lens is inclined with respect to a reference beam which is defined as a beam reaching a center of a viewpoint region of the observer and corresponding to a center of the virtual image.