Head-Up Display Optical Layout for Compact, Low-Distortion Projection
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Solution Overview
Problem
Existing head-up displays face challenges in reducing size while maintaining image quality and preventing stray light from outside sources, which affects the clarity and distortion of the virtual image projected for the observer.
Innovation Solution
The head-up display incorporates a projection optical system with a first lens and a first optical element, such as a mirror, disposed in a specific order along the optical path to condense and diffuse light, and are inclined with respect to a reference beam to form an intermediate image that is larger than the original image, allowing for a smaller display size and effective inhibition of stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the head-up display uses a conventional optical system configuration, then the image can be projected clearly, but the overall device size becomes large
Solution Approach 1:
The patent implements a nested optical system where the first optical system (forming intermediate image) is integrated within the second optical system (projecting to windshield). The intermediate image is formed in space between the two optical systems, allowing compact arrangement of multiple optical functions in a nested configuration that reduces overall device volume while maintaining image quality.
Solution Approach 2:
The patent introduces an intermediate image dimension in space, creating a three-stage optical path (display surface → intermediate image → windshield) that allows compact folding of the optical system. This dimensional approach enables the optical components to be arranged more efficiently in space, reducing the overall footprint of the head-up display.
2Volume of moving object
If the head-up display uses a compact optical system, then the device size is reduced, but stray light from outside sources increases
Solution Approach 1:
The patent introduces an intermediate image as a mediator between the display surface and the final projected image on the windshield. This intermediate stage allows for better control of light paths and enables the optical systems to more effectively manage stray light while maintaining compact dimensions.
Solution Approach 2:
The patent extracts and separates the light condensing function into a dedicated first optical system that forms the intermediate image, distinct from the second optical system that projects to the windshield. This separation allows each system to be optimized independently for their specific functions, improving stray light rejection while maintaining compact size.
3Area of moving object
If the head-up display enlarges the image significantly, then the virtual image appears larger, but distortion increases
Solution Approach 1:
The patent divides the magnification function into two separate optical systems: the first optical system provides initial magnification to form the intermediate image, and the second optical system provides additional magnification for the final projected image. This segmentation of magnification stages allows for better control and correction of distortion at each stage, enabling large virtual image size with reduced overall distortion.
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 configuration reduces the size of the head-up display while providing a less distorted virtual image and effectively inhibiting stray light, enhancing the observer's visual experience by maintaining image quality and clarity.
Implementation Method 1
a first lens configured to condense light
Implementation Method 2
a first optical element configured to diffuse light
Implementation Method 3
project an image on a transparent reflection member to cause an observer to visually recognize a virtual image
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.