Projection Lens Position Adjustment with Intersecting Rotation Axes
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Solution Overview
Problem
Existing projection systems face challenges in achieving precise Scheimpflug adjustments without affecting the back focal length and image focus, particularly when using facetted or curved screens, due to issues with friction-based solutions and the need for iterative adjustments.
Innovation Solution
A position adjustment system for the projection lens with intersecting and perpendicular axes of rotation near the nodal point, allowing independent Scheimpflug adjustments with a low-friction mechanism and secure locking, minimizing the impact on image focus and position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If friction-based spherical joints are used for Scheimpflug adjustment, then the lens can be tilted and positioned, but the adjustment becomes difficult due to stick-slip effects and locking becomes problematic
Solution Approach 1:
The patent replaces the friction-based spherical joint mechanism with a pivotable mounting system that uses defined rotation axes with minimal friction. This substitution eliminates the stick-slip effects inherent in spherical joints while maintaining the ability to tilt and position the lens, and provides reliable positioning through the pivotable connection.
Solution Approach 2:
The patent changes the mechanical parameters of the adjustment system by specifying precise rotation axes that are perpendicular to the optical axis and positioned at specific locations. This parameter optimization reduces friction and eliminates the problematic stick-slip effects while maintaining adjustment capability and position stability.
2Ease of operation
If the projection lens is tilted for Scheimpflug adjustment, then focus correction is achieved, but the back focal length changes requiring iterative refocusing
Solution Approach 1:
The patent performs preliminary action by carefully positioning the rotation axes perpendicular to the optical axis and near the nodal point before adjustment begins. This preliminary configuration ensures that tilting the lens for Scheimpflug correction produces minimal change in back focal length, thereby reducing or eliminating the need for iterative refocusing adjustments.
Solution Approach 2:
The patent uses the nodal point as an intermediary reference for positioning the rotation axes. By locating the axes near the nodal point and orienting them perpendicular to the optical axis, the system mediates between the need for tilt adjustment and the need to maintain focus, allowing Scheimpflug correction with minimal impact on back focal length.
3Ease of operation
If spherical joints with smooth curved surfaces are used, then lens positioning is achieved, but the system becomes expensive and unsuitable for heavy lenses
Solution Approach 1:
The patent adopts a simpler, more cost-effective pivotable mounting system instead of expensive spherical joints with precision curved surfaces. This simpler mechanism achieves the required lens positioning capability without the high manufacturing costs associated with smooth curved surfaces, making it suitable for heavy projection lenses while maintaining functionality.
Data Source
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AI summary
A lens position adjustment system (10) permits adjustment of the position of a projection lens (5) relative to a projector (100) for making a Scheimpflug adjustment. The projection lens (5) has an optical axis (6). The system (10) comprises: a first support part (20) for fitting to, or forming part of, the projector (100); a second support part (40) for fitting to, or forming part of, the projection lens (5); and a connecting part (30). The connecting part (30) is pivotally connected to the first support part (20) and pivotally connected to the second support part (40) and configured to permit independent adjustment of the second support part (40) relative to the first support part (20) about two axes of rotation (7, 8) which intersect, and are perpendicular to, the optical axis (6) of the projection lens (5). A locking mechanism (28, 29, 51-58) is provided for securing a position of the second support part (40) relative to the first support part (20).