Compact Head-Up Display Optics With Single Concave Mirror
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Solution Overview
Problem
Conventional head-up display (HUD) apparatuses face limitations in size reduction due to the need for two mirrors in the optical path, which restricts the layout and increases the housing size.
Innovation Solution
The HUD apparatus employs a direct optical system using only a concave mirror to project images onto a windshield, combined with a distortion correcting lens to reduce distortion and aberration, and a specially designed housing to minimize size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two mirrors are installed between the observer and display apparatus to achieve image projection, then the virtual image can be displayed, but the apparatus size and housing capacity increase
Solution Approach 1:
The patent removes one mirror from the traditional two-mirror optical system, extracting only the essential reflective element (single mirror) needed to achieve the virtual image projection function. This simplification directly reduces the apparatus size while maintaining the core functionality of displaying information on the windshield.
Solution Approach 2:
The patent segments the optical system into distinct functional components: a single mirror for reflection, a combiner for image superposition, and a display apparatus. This segmentation allows for optimized spatial arrangement and reduced overall size compared to the integrated two-mirror system.
2Volume of stationary object
If two mirrors are closely disposed to reduce size, then the apparatus capacity decreases, but the reflected light flux may be shielded
Solution Approach 1:
The patent introduces a combiner as an intermediary optical element between the mirror and the observer. The combiner transmits the reflected light flux from the single mirror to the observer's eye, preventing shielded light flux while enabling compact arrangement of optical components. This intermediary component ensures reliable light transmission in the reduced-size configuration.
3Volume of stationary object
If a single mirror is used instead of two mirrors, then the apparatus size is reduced, but distortion and aberration may increase
Solution Approach 1:
The patent employs a composite optical system combining a mirror (reflective element) with a combiner (transmissive element with specific optical properties). This composite configuration allows the single-mirror system to achieve both size reduction and maintained image quality, as the combiner is designed to correct distortions while transmitting light.
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 allows for a further reduction in the size of the HUD apparatus while maintaining effective image projection and correction, enhancing visual confirmation and reducing the apparatus's bulkiness.
Implementation Method 1
a virtual image optical system configured to reflect the light emitted from the image display apparatus onto a windshield
Implementation Method 2
by designing a relationship among an incident angle in an image long axis direction in the first mirror, an incident angle in an image short axis direction in the first mirror
Data Source
AI summary
An object of the present invention is to provide a head-up display apparatus further reduced in size, the head-up display apparatus having: an image display apparatus including a light source and a display element; and a virtual image optical system in which light emitted from the image display apparatus is reflected by a windshield or a combiner of the vehicle so that a virtual image is displayed in front of the vehicle, wherein the virtual image optical system has a concave mirror and a distortion correcting lens, and the distortion correcting lens is disposed between the image display apparatus and the concave mirror, the concave mirror is disposed in a housing including an outer case along a shape of an effective light path area of the image light from the image display apparatus, and the image display apparatus is attached to part of an outer periphery of the housing.