Head-Up Display Eyepiece Optical System for Wide Viewing Angle
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Solution Overview
Problem
Existing head-up display systems face limitations in providing a wide viewing angle while maintaining a compact size, leading to cramped in-vehicle space and longer recognition times due to the need for larger combiners and restricted eye relief.
Innovation Solution
A projection optical system incorporating an eyepiece optical system with a negative refractive power lens, a positive refractive power lens, and a concave reflecting mirror, arranged to increase the viewing angle by reflecting image light on the windshield, allowing for a wider field of view without increasing the apparatus size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a combiner-type head-up display is used to increase viewing angle, then the viewing angle increases, but the apparatus size increases causing cramped in-vehicle space
Solution Approach 1:
The patent transitions from a combiner-type configuration to a windshield-type configuration, utilizing the windshield surface as the projection medium. This dimensional change allows the virtual image to be formed on the windshield rather than requiring a separate combiner component, thereby increasing the viewing angle while avoiding the space consumption of a dedicated combiner assembly.
Solution Approach 2:
The windshield serves multiple functions: it acts as both the vehicle's protective barrier and the projection screen for the head-up display. By utilizing the existing windshield structure for image projection, the system eliminates the need for a separate combiner component, thus achieving a wider viewing angle without increasing the overall apparatus size.
2Volume of moving object
If a combiner is placed near the observer to reduce apparatus size, then the apparatus size is reduced, but the observer experiences cramped space feeling and longer recognition time
Solution Approach 1:
The windshield serves as the projection medium, positioned far from the observer's eyes. This allows the virtual image to be formed at a distance that does not interfere with the observer's forward view, eliminating the cramped space feeling and reducing the time required to recognize image information while maintaining a compact apparatus design.
3Volume of moving object
If a windshield-type display with small display panel is used, then the apparatus size is reduced, but the viewing angle becomes too narrow to display sufficient image information
Solution Approach 1:
The patent employs aspheric lens surfaces in the projection optical system to correct optical aberrations and expand the effective viewing angle. The curved aspheric surfaces enable wider angular coverage while maintaining image quality, allowing a compact display panel to project sufficient image information across a broader viewing angle.
Solution Approach 2:
The system utilizes optical parameter optimization in the projection lens design, including focal length, aperture, and aspheric coefficients, to maximize the viewing angle achieved from a compact display panel. By carefully adjusting these optical parameters, the system achieves an expanded viewing angle without increasing the physical size of the display apparatus.
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 enables a head-up display apparatus with a significantly wider viewing angle of up to 11.6 degrees horizontally and 1.8 degrees vertically, while maintaining a longer eye relief, thus improving image quality and reducing spatial constraints within the vehicle.
Implementation Method 1
an eyepiece optical system that causes a virtual image to be displayed by reflecting light emitted from an image formation unit forming image information
Data Source
AI summary
A head-up display apparatus is provided which enables a wide viewing angle in spite of being a type that reflects image light on a windshield. Accordingly, a head-up display apparatus (110) includes an image formation unit (10) that displays image information, and a projection optical system that includes an eyepiece optical system 5 reflecting light emitted from the image formation unit (10) for display of a virtual image. The eyepiece optical system (5) includes a first optical element (51) having a negative refractive power, a second optical element (52) having a positive refractive power, and a concave reflecting mirror (54), and is configured to arrange the first optical element (51), the second optical element (52) and the reflecting mirror (53) in this order from the image formation unit.