Folded Projection Optical System for Compact Ultra-Wide-Angle Displays
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Solution Overview
Problem
Current projectors compatible with ultra-wide-angles face challenges in miniaturization and performance enhancement, necessitating a technology that can efficiently manage optical path length and environmental changes while maintaining imaging quality.
Innovation Solution
The image display apparatus incorporates a projection optical system with a first lens system, a first reflective optical system, and a second lens system, along with a second reflective optical system, where the image light is folded back and reflected by each of the first and second reflection surfaces, ensuring a sufficient optical path length without increasing system size, and the linear expansion coefficients of the optical parts are defined within specific ranges to suppress environmental influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical path length is increased to ensure sufficient image quality, then the imaging performance is improved, but the size of the projection optical system increases
Solution Approach 1:
The patent employs multiple reflection surfaces (first reflection surface, second reflection surface, and concave reflection surface) to fold the optical path, transforming a linear optical path into a multi-dimensional folded structure. This allows the optical path length to be extended without increasing the overall system size in any single dimension, effectively resolving the contradiction between imaging performance and system compactness
Solution Approach 2:
The optical components are arranged in a nested configuration where the first lens system, first reflective optical system, second lens system, and second reflective optical system are positioned sequentially along a folded optical path. This nesting allows multiple optical elements to occupy overlapping spatial volumes, maximizing the optical path length within a compact footprint
2Ease of manufacture
If the linear expansion coefficient of optical parts is increased to reduce manufacturing costs, then the manufacturing cost is reduced, but the influence of environmental changes on imaging quality increases
Solution Approach 1:
The patent specifies precise ranges for the linear expansion coefficients (α1 for first optical part, α2 for second optical part) and conditional expressions involving these coefficients. By controlling these thermal expansion parameters within specific ranges, the patent achieves a balance between using cost-effective materials and maintaining stable imaging performance under environmental variations
Solution Approach 2:
Different optical parts (first optical part with first reflection surface, second optical part with second reflection surface) are assigned different linear expansion coefficient requirements tailored to their specific positions and functions in the optical path. This localized optimization allows each component to be manufactured with appropriate material properties, balancing cost and environmental stability
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 enables the miniaturization of the projector while maintaining high performance and stability across varying environmental conditions, allowing for ultra-wide-angle projections even in limited spaces with improved assembly accuracy and reduced material costs.
Implementation Method 1
The first lens system has a positive refractive power as a whole and refracts the generated image light
Implementation Method 2
the first reflection surface folding back and reflecting the image light refracted by the first lens system
Implementation Method 3
the second reflection surface folding back and reflecting the image light reflected by the first reflection surface
Implementation Method 4
The second lens system has a positive refractive power as a whole and refracts the image light reflected by the second reflection surface
Implementation Method 5
The second reflective system has a concave reflection surface reflecting the image light refracted by the second lens system toward an object to be projected
Data Source
Figure 1~2
Figure 3
Figure 4A~4C
AI summary
The present image display apparatus includes: a light source; an image generation unit; and a projection optical system. The image generation unit generates image light on the basis of light from the light source. The projection optical system includes a first lens system, a first reflective optical system, a second lens system, and a second reflective optical system. The first lens system refracts the generated image light. The first reflective optical system has first and second reflection surfaces that fold back and reflect the image light refracted by the first lens system. The second lens system refracts the image light reflected by the second reflection surface. The second reflective system has a recessed reflection surface for reflecting the image light refracted by the second lens system toward an object to be projected. Further, the image display apparatus is configured to satisfy the following relationship: 5×10-7<α1<3×10-5 where α1 represents a linear expansion coefficient of a first optical part on which the first reflection surface is formed.