Head-Up Display Projection Optical System with Variable Mirror Power
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Solution Overview
Problem
Existing head-up display devices for large vehicles face challenges in reducing size while maintaining performance and correcting optical aberration, and in minimizing driver eye movement and eyestrain by optimizing the focal position and optical path length.
Innovation Solution
A head-up display device with a projection optical system comprising a first mirror with negative power and a second mirror with positive power, where the power ratios of these mirrors and their combined optical system are optimized to satisfy specific conditional expressions, allowing for a longer optical path and reduced size, along with a variable angle of luminous flux adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the optical path length between the image display surface and the reflective optical surface is increased to make the focal position distant, then driver eye movement is reduced and eyestrain is prevented, but the device size increases
Solution Approach 1:
The projection optical system is divided into multiple reflective optical elements (first mirror, second mirror, and reflective optical surface) that work together to achieve the required optical path length. This segmentation allows the system to extend the optical path while keeping the physical device compact, as each mirror contributes to the overall light deflection without requiring a proportionally large device volume.
Solution Approach 2:
The patent utilizes multi-dimensional spatial arrangement of mirrors to extend the optical path. By configuring mirrors at different positions and angles in three-dimensional space, the system achieves a long effective optical path between the image display surface and the reflective optical surface without increasing the device's footprint or volume proportionally.
2Adaptability or versatility
If the device size is reduced to increase arrangement freedom in large vehicles, then adaptability is improved, but optical aberration correction becomes more difficult
Solution Approach 1:
The patent employs specific power ratio parameters for the mirrors to achieve optimal optical performance in a compact configuration. By carefully selecting and adjusting the power parameters of the first and second mirrors according to the conditional expressions, the system corrects optical aberrations while maintaining a reduced device size suitable for various vehicle arrangements.
Solution Approach 2:
The projection optical system uses a composite configuration of multiple mirrors with different power characteristics (positive and negative power mirrors) to achieve both compact size and effective aberration correction. This composite optical design allows the system to leverage the complementary properties of different mirror elements to correct various types of optical aberrations within a small form factor.
3Reliability
If mirrors with specific power ratios are used to correct optical aberration and reduce size, then device performance is improved, but the design complexity increases
Solution Approach 1:
The patent defines specific parameter ranges for mirror powers through conditional expressions to achieve optimal optical performance. By establishing these parameter relationships, the design process is guided toward solutions that simultaneously correct optical aberrations and maintain compact size, reducing the complexity of finding suitable design configurations.
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 enhances performance by reducing size, correcting optical aberration, and minimizing driver eye movement, thereby improving safety and reducing eyestrain by maintaining a longer focal position and adjustable luminous flux.
Implementation Method 1
a projection optical system that projects an image displayed on an image display surface to a reflective optical surface
Data Source
AI summary
A head-up display device is improved in performance by a reduction in size and the satisfactory correction of optical aberration. A head-up display device includes a projection optical system that projects an image displayed on an image display surface to a reflective optical surface disposed at a position facing an predetermined observation position of an observer and allows the observer to visually recognize the enlarged image as a virtual image. In a case in which an optical path, which extends from a center of the image display surface and reaches a center of an eye box, is referred to as an optical axis, the projection optical system includes a first mirror having negative power near the optical axis and a second mirror having positive power near the optical axis in this order from the image display surface and Conditional Expressions (1) and (2) are satisfied.