Free-Form Reflecting Members for Head-Up Display Distortion Correction
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Solution Overview
Problem
Existing display technologies face challenges in projecting high-quality virtual images onto a light transmissive display member, such as windshields, due to field curvature and distortion issues, which affect the user's ability to perceive a clear and undistorted image.
Innovation Solution
A display apparatus with a projection optical system that includes a first reflecting member with a convex free-form surface and a second reflecting member with a concave free-form surface, positioned to project images onto a light transmissive display member, allowing for correction of screen distortion and downsizing of the display unit while maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional projection optical system is used, then the display unit can project images to the display member, but field curvature and screen distortion occur affecting image quality
Solution Approach 1:
The first reflecting member is configured with a convex free-form surface and the second reflecting member with a concave free-form surface. These curved surfaces are specifically designed to correct field curvature and screen distortion, transforming the optical path to eliminate image quality degradation while maintaining a compact display unit structure.
2Volume of moving object
If the display unit is downsized, then the housing becomes more compact, but it becomes difficult to correct screen distortion and maintain image quality
Solution Approach 1:
By implementing free-form curved surfaces on the reflecting members, the patent achieves effective correction of screen distortion within a compact housing. The curved surfaces enable sophisticated light path control that would normally require larger optical systems, thus maintaining image quality while reducing overall display unit size.
Solution Approach 2:
The projection optical system is integrated within a compact housing structure where the first and second reflecting members are positioned in sequence. The optical components are nested within the housing boundaries, with the convex and concave surfaces working together in a confined space to achieve distortion correction without requiring excessive volume.
3Manufacturing precision
If the convex and concave free-form surfaces are used, then screen distortion is corrected, but the device complexity increases
Solution Approach 1:
The patent combines the functions of field curvature correction and screen distortion correction into a single projection optical system using two reflecting members with complementary free-form surfaces. This merged approach achieves multiple correction objectives simultaneously, reducing the need for separate correction components and thereby limiting the increase in device complexity.
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 effectively corrects screen distortion and allows for a larger virtual image to be perceived by the user within a smaller display unit, enhancing image quality and user experience by ensuring the image is clear and undistorted across the entire visually recognizable region.
Implementation Method 1
a reflection surface of the first reflecting member that reflects the image displayed on the display device has a convex shape of a free-form surface
Implementation Method 2
a reflection surface of the second reflecting member that projects the image to the display member has a concave shape of a free-form surface
Data Source
AI summary
A display apparatus includes a display unit that projects an image to a light transmissive display member. The display unit is configured to accommodate a display device and a projection optical system that projects the image displayed on the display device to the display member in a housing including an opening through which projected light is output. The projection optical system includes a first reflecting member disposed on a display device side and a second reflecting member disposed on an opening side in an optical path extending from the display device to the opening. A reflection surface of the first reflecting member that reflects the image displayed on the display device has a convex shape of a free-form surface, and a reflection surface of the second reflecting member that projects the image to the display member has a concave shape of a free-form surface.