Compact Wide-Angle Imaging Optics With Dust-Protection Window
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Solution Overview
Problem
Existing imaging optical systems for projection type display devices and imaging apparatuses face challenges in preventing dust penetration while maintaining a compact size and achieving wide-angle views without distortion.
Innovation Solution
An imaging optical system comprising an optical window, a reflective optical system with specific reflecting surfaces, and a refractive optical system, configured to form intermediate images and ensure the optical window is positioned to prevent dust penetration, with conditional expressions defining the angles and positions of optical elements to achieve a compact and wide-angle design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an optical window is added to prevent dust penetration, then reliability is improved, but device size increases
Solution Approach 1:
The optical window is integrated within the existing optical path structure, nesting it among the lenses and reflective surfaces. The window is positioned to be incident to by principal rays without requiring additional external space, effectively embedding the dust-prevention function within the compact optical assembly.
Solution Approach 2:
The optical window is tilted at a specific angle (45 degrees or more) relative to the optical axis, utilizing angular positioning in another dimension to achieve both dust prevention and compact size. This tilt allows the window to intercept dust particles while maintaining compatibility with the existing optical path geometry.
2Adaptability or versatility
If a reflective optical system is used to achieve wide-angle view, then field of view is improved, but optical path complexity increases
Solution Approach 1:
The patent extracts and isolates the wide-angle functionality into a dedicated reflective optical system with specific reflecting surfaces (first, second, and third reflecting surfaces with defined powers and angles). This separation allows the reflective components to handle the wide-angle requirement independently, simplifying the overall design by clearly dividing functions between reflective and refractive elements.
Solution Approach 2:
The patent employs specific parameter configurations for the reflecting surfaces, including precise power values and angular orientations (e.g., the first reflecting surface at 45 degrees or more). By optimizing these parameters, the system achieves wide-angle capability while controlling the complexity through mathematical constraints and defined geometric relationships.
3Reliability
If the optical window is positioned to prevent dust penetration, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The optical window is pre-positioned at a specific tilt angle (45 degrees or more) relative to the optical axis during manufacturing. This preliminary angular orientation ensures that the window will effectively intercept dust particles while providing a clear optical path for principal rays. The pre-established geometric relationship simplifies subsequent assembly and reduces the need for high-precision adjustment.
Solution Approach 2:
The tilted optical window acts as an intermediary element that mediates between the external environment (dust particles) and the internal optical path. Its specific angular positioning creates a geometric buffer that naturally directs dust particles away from the optical axis while allowing light to pass through, thereby reducing the stringency of precision requirements for other components.
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 system effectively prevents dust penetration and reduces size while enabling wide-angle views without distortion, enhancing the performance and reliability of projection type display devices and imaging apparatuses.
Implementation Method 1
an optical window W, a reflective optical system GR, and a refractive optical system GL including a plurality of lenses along an optical path
Implementation Method 2
the reflective optical system includes a first reflecting surface having a positive power, a second reflecting surface having a power, and a third reflecting surface having a positive power along the optical path
Implementation Method 3
a refractive optical system GL including a plurality of lenses along an optical path in order from an enlargement side to a reduction side
Data Source
AI summary
The imaging optical system is capable of forming an enlarged image on an enlargement-side imaging plane by enlarging an image on a reduction-side imaging plane, the imaging optical system consisting of an optical window, a reflective optical system, and a refractive optical system including a plurality of lenses along an optical path in order from an enlargement side to a reduction side, in which at least two intermediate images are formed. The reflective optical system includes a first reflecting surface having a positive power, a second reflecting surface having a power, and a third reflecting surface having a positive power along the optical path in order from the enlargement side to the reduction side. A center of the enlarged image is at a position shifted from an optical axis of the refractive optical system in a direction perpendicular to the optical axis. The imaging optical system satisfies predetermined conditional expressions.