Microprojector Optical System Fixation for Light Axis Stability
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Solution Overview
Problem
Microprojectors face challenges in achieving a compact configuration and maintaining display performance due to light axis misalignment caused by temperature variations, weight distribution, and structural deformation of the frame, especially in short-focus types where the projection optical system has a smaller throw ratio.
Innovation Solution
The illumination optical system and projection optical system are assembled integrally, with only the heavier system fixed to the frame, reducing the likelihood of light axis misalignment and allowing for a more compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If both the illumination optical system and the projection optical system are fixed to the frame, then the structural stability is improved, but the overall size and weight of the microprojector increases
Solution Approach 1:
The patent divides the fixation system into two parts: the frame and the optical systems. Instead of fixing both optical systems directly to the frame, only the projection optical system is fixed to the frame, while the illumination optical system is fixed to the projection optical system. This segmentation reduces the number of fixation points and the overall structural weight while maintaining stability.
Solution Approach 2:
The projection optical system serves as an intermediary between the frame and the illumination optical system. By fixing the illumination optical system to the projection optical system rather than directly to the frame, the patent creates a cascaded fixation structure that reduces the overall weight and complexity of the mounting structure while maintaining structural stability.
2Reliability
If the frame is structurally reinforced to support both systems, then the light axis misalignment is reduced, but the size and weight of the microprojector increases
Solution Approach 1:
The patent segments the fixation structure so that the projection optical system is fixed to the frame, and the illumination optical system is fixed to the projection optical system. This segmentation allows for a thinner, lighter frame while maintaining light axis alignment through proper fixation of the heavier projection optical system to the frame.
Solution Approach 2:
The patent replaces the need for a thick, heavily reinforced frame with a lighter fixation structure. By strategically fixing only the projection optical system (which has a larger weight) to the frame, the patent achieves light axis alignment without requiring excessive frame thickness, thus substituting mechanical reinforcement with a more efficient fixation strategy.
3Length of moving object
If the microprojector is designed for ultra-short focus (throw ratio ≤ 0.38), then the projection distance is reduced, but the light axis misalignment due to frame deformation increases
Solution Approach 1:
The patent segments the fixation structure into two levels: the projection optical system fixed to the frame, and the illumination optical system fixed to the projection optical system. This segmentation provides a stable reference frame for the projection system while allowing the illumination system to be positioned relative to it, thereby maintaining light axis alignment even in ultra-short focus configurations where frame deformation is more likely.
Data Source
AI summary
An image projection apparatus includes: an illumination optical system; a projection optical system assembled integrally with the illumination optical system; and a frame fixed to only one system, that has a larger weight, of the illumination optical system and the projection optical system.