Movable Aperture with Swollen Portion for Stray Light Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In projector systems, increasing the opening size to enhance image brightness leads to increased stray light entry, deteriorating image contrast due to expanded beam diameters of ON-state, OFF-state, and stray light, which affects the sharpness and brightness of projected images.
Innovation Solution
A projection lens with a movable aperture that moves along the optical axis, featuring a circular opening with a swollen portion on its circumferential edge, positioned to project towards the center of stray light, effectively cutting off stray light and allowing more ON-state light to pass through, thereby maintaining image sharpness and brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the opening size in the illumination side optical system or projection side optical system is increased to enhance image brightness, then the brightness of the projected image is improved, but the diameters of ON-state light beam, OFF-state light beam and stray light beam are expanded, increasing the chance of stray light entering the projection lens and deteriorating image contrast
Solution Approach 1:
The aperture is designed with non-uniform structure, featuring a swollen portion that protrudes into the aperture from the circumferential edge. This creates different local properties within the same aperture: the swollen portion blocks stray light while the rest of the aperture maintains large opening for brightness. The aperture thus has differentiated functionality within its structure, allowing simultaneous optimization of brightness and stray light rejection.
Solution Approach 2:
The aperture breaks the traditional symmetric circular design by introducing a swollen portion at a specific location on the circumferential edge. This asymmetric structure is positioned to specifically intercept stray light beams while minimizing impact on the main optical path. The asymmetric design allows targeted stray light blocking without uniformly reducing the aperture opening, thus maintaining brightness while improving contrast.
2Quantity of substance
If the opening size is increased to enhance image brightness, then more light passes through the system, but stray light also enters the projection lens more easily, resulting in deteriorated image contrast and sharpness
Solution Approach 1:
The aperture structure incorporates a swollen portion that creates localized light blocking capability. This allows the aperture to simultaneously perform two functions: maintaining a large overall opening for high light transmission quantity, and providing localized obstruction to prevent stray light from reaching the projection lens. The local quality modification thus preserves brightness while protecting image sharpness.
3Ease of manufacture
If a traditional circular aperture is used, then the structure is simple and manufacturing is easy, but stray light cannot be effectively blocked and image contrast deteriorates
Solution Approach 1:
The aperture design introduces a swollen portion that modifies the traditional circular shape. While this adds some manufacturing complexity, the modification is localized and can be achieved through standard molding or machining processes. The benefit is substantial: the swollen portion effectively blocks stray light without requiring complete redesign of the entire aperture, thus maintaining relative manufacturing simplicity while dramatically improving stray light rejection capability.
Solution Approach 2:
The asymmetric swollen portion is strategically positioned on the circumferential edge of the circular aperture. This asymmetric feature is designed to intercept stray light beams that enter at specific angles, providing effective stray light blocking with minimal structural modification. The asymmetric design achieves superior optical performance without requiring complete redesign of the aperture geometry.
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 solution effectively reduces stray light entry, enhancing image contrast and brightness while maintaining sharpness, even at varying zoom settings, by strategically positioning the movable aperture to absorb stray light and increase the aperture size for ON-state light transmission.
Implementation Method 1
the swollen portion projects towards the opening from a circumferential edge portion which is in a direction of a center of a beam of stray light... effectively cutting off stray light
Data Source
AI summary
There is provided a projection lens for a projector which utilizes a reflection type display device, comprising a movable aperture 70 which is movable as a movable lens components moves, wherein an opening 75 in the movable aperture 70 is formed into a circular shape which is centered at the center of an optical axis 69 of the projection lens and has a swollen portion 73 on part of the opening 75 in such a manner as to project from a circumferential portion in a direction of the center of a beam of stray light into the interior of the opening 75.