Lens Shift Mechanism Rattle Reduction via Opposing Elastic Bias
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Solution Overview
Problem
Existing lens shift mechanisms in projection display apparatuses suffer from rattling issues due to clearance in the lens shift apparatus, which affects the stability of the projection image position, and existing solutions either require high frictional forces or increase the load on the drive mechanism.
Innovation Solution
A lens shift mechanism that incorporates a pair of main and countershafts extending perpendicular to the optical axis, combined with elastic bodies having opposite biasing directions, to reduce rattling and improve stability without increasing the load on the drive mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If clearance is provided in the lens shift apparatus for operating the projection lens, then the lens can move freely to adjust image position, but rattling occurs which reduces projection image position stability
Solution Approach 1:
The elastic bodies are pre-loaded to apply biasing forces before the lens shift operation begins. This preliminary action creates initial contact pressure between the lens holder and the support structure, eliminating clearance-induced rattling before any movement occurs, while still allowing the lens to be shifted when force is applied.
Solution Approach 2:
The elastic bodies act as cushioning elements that absorb and dampen vibrations and rattling forces. By placing these elastic bodies between the lens holder and support structure, they provide beforehand cushioning that prevents rattling from propagating during lens operation, maintaining projection stability while preserving movement capability.
2Device complexity
If a single elastic body is used to eliminate rattling, then the structure is simple, but the load on the drive mechanism increases
Solution Approach 1:
The single elastic body is segmented into multiple elastic bodies arranged in parallel. Each elastic body carries a portion of the rattle-prevention function, distributing the force requirements. This segmentation reduces the load on the drive mechanism while maintaining the same level of rattling elimination effectiveness.
Solution Approach 2:
The multiple elastic bodies are configured with biasing directions that oppose each other, creating a balanced force system. This counterbalancing arrangement reduces the net force required from the drive mechanism to operate the lens, as the opposing biasing forces cancel out during normal operation while still maintaining contact pressure to eliminate rattling.
3Reliability
If frictional force is increased to remove rattling, then projection image stability improves, but the load on the drive mechanism increases
Solution Approach 1:
The elastic bodies are configured with opposite biasing directions that create a balanced force system. During lens movement, the opposing biasing forces cancel each other out, reducing the net force the drive mechanism must overcome. This allows sufficient frictional force to be generated for rattling elimination without proportionally increasing the drive load.
Solution Approach 2:
The elastic bodies are designed with specific biasing force parameters that optimize the balance between friction generation and drive load. By carefully selecting the elasticity and pre-load parameters, the system generates just enough friction to eliminate rattling while minimizing the force requirement for the drive mechanism.
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 mechanism effectively reduces rattling and enhances the stability of the projection image position by utilizing the opposing biasing forces of the elastic bodies, allowing for precise movement of the projection lens without burdening the support or drive mechanisms.
Implementation Method 1
generate a frictional force to remove rattling
Implementation Method 2
a pair of elastic bodies parallel to the same one axial direction and having biasing directions opposite to each other
Data Source
Figure 1
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AI summary
A lens shift mechanism of one embodiment of the present disclosure includes: a projection lens; a cylindrical housing that holds the projection lens; and an operating unit that moves the cylindrical housing in one axial direction perpendicular to an optical axis of the projection lens. The operating unit includes a pair of a main shaft and a countershaft extending in the one axial direction and disposed to be opposed to each other across the cylindrical housing, and a pair of elastic bodies provided respectively for the main shaft and the countershaft. The pair of elastic bodies are parallel to the one axial direction, and have biasing directions opposite to each other.