Head-Up Display Projection Distance Control Using Segmented Optical Paths
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Solution Overview
Problem
Conventional head-up displays face challenges in maintaining display quality when projecting images onto multiple screens at different distances, as increasing the curvature of projection distance changing units can lead to image distortion.
Innovation Solution
A display device with a projector emitting light to two screens at different distances, using a negative refractive power unit to extend the projection distance for the first screen and a positive refractive power unit to shorten it for the second screen, ensuring the optical path of the first image is shorter than the second, thereby preventing distortion and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the curvature of the projection distance changing unit is increased to extend the projection distance, then the projection distance can be extended, but the image may be distorted
Solution Approach 1:
The patent divides the projection optical path into two separate paths: one for the first screen (using a projection distance extending unit with negative refractive power) and one for the second screen (using a projection distance shortening unit with positive refractive power). This segmentation allows each optical path to be optimized independently, preventing image distortion while achieving different projection distances.
Solution Approach 2:
The patent applies opposite refractive power approaches for the two projection paths: using negative refractive power (concave lens or convex mirror) for extending the projection distance to the first screen, and positive refractive power (convex lens or concave mirror) for shortening the projection distance to the second screen. This inversion of optical approaches resolves the contradiction by allowing distance adjustment without excessive curvature.
2Device complexity
If a single projector is used to project images onto two screens at different distances, then the device complexity is reduced, but the projection distance control for each screen becomes difficult
Solution Approach 1:
The patent segments the projection light from a single projector into two separate optical paths using beam splitting or spatial separation. Each path has its own projection distance control unit (extending unit for the first screen, shortening unit for the second screen), enabling independent distance control while using only one projector.
Solution Approach 2:
The patent applies different optical characteristics to different parts of the projection system: the first projection path uses components with negative refractive power for distance extension, while the second path uses components with positive refractive power for distance shortening. This local differentiation enables precise control of projection distances for each screen.
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 the display of multiple images at different distances without reducing image quality, ensuring the viewer recognizes virtual images clearly and accurately.
Implementation Method 1
a projection distance extending unit disposed on a path of the first projection light between the projector and the first screen, having negative refractive power (optical power), and configured to extend a projection distance of the first projection light
Implementation Method 2
a projection distance shortening unit disposed on a path of the second projection light between the projector and the second screen, having positive refractive power (optical power), and configured to shorten a projection distance of the second projection light
Data Source
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AI summary
The present invention displays multiple images at different locations in the depth direction, while suppressing a decline in display quality, using projected light emitted from a single projector. A projector 20 emits first projection light L1 and second projection light L2 that have a first projection distance P1. A projection distance lengthening unit 251 having a negative refractive power is positioned along the path of the first projection light L1 between the projector 20 and a first screen 23, and causes an image to be formed on the first screen 23 by lengthening the projection distance P of the first projection light L1. A projection distance shortening unit 252 having a positive refractive power is positioned along the path of the second projection light L2 between the projector 20 and a second screen 24, and causes an image to be formed on the second screen 24 by lengthening the projection distance P of the second projection light L2.