Projection Device Light Shielding Member Stray Light Reduction
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Solution Overview
Problem
Existing projection devices face challenges in reducing stray light while maintaining a compact device size, as conventional solutions often require larger optical systems or complex light shielding mechanisms that increase device size and complexity.
Innovation Solution
A projection device with a light shielding member positioned within the air space to shield stray light, featuring a light shielding region outside the effective luminous flux paths and a light transmission region that allows the passage of effective flux, with specific area ratios and positional relationships between the light shielding member and the display element to optimize stray light reduction without increasing device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light shielding member is added to reduce stray light, then stray light reduction is improved, but device size increases
Solution Approach 1:
The light shielding member is positioned within the air space of the projection optical system, nesting the shielding function inside the existing optical path. The light shielding region is configured to be positioned outside optical paths of all effective luminous fluxes while allowing the light transmission region to surround it, creating a nested structure that reduces stray light without significantly increasing device volume
Solution Approach 2:
The light shielding member is designed with specific area ratios where the light transmission region area STr and light shielding region area SH are optimized relative to the display region area SD. By controlling the ratio STr/SD and SH/STr, the member provides localized light shielding exactly where needed (outside effective luminous flux paths) while maintaining compact dimensions
2Object-affected harmful factors
If the light shielding member area is increased to reduce stray light, then stray light reduction is improved, but device complexity increases
Solution Approach 1:
The invention optimizes the geometric parameters of the light shielding member, specifically the area ratios STr/SD and SH/STr, and the positional parameter D/IM (distance from paraxial image-forming position divided by image circle diameter). By adjusting these parameters within specified ranges, the system achieves effective stray light reduction with minimal mechanical complexity
Solution Approach 2:
The light shielding member serves multiple functions simultaneously: it shields stray light, maintains compact device size through optimized area ratios, and can be positioned at specific locations within the air space. The single member structure handles both the shielding function and the spatial constraint, reducing overall system complexity
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
Effectively reduces stray light while maintaining a compact device size by optimizing the position and area of the light shielding member relative to the display element and projection optical system, enhancing image quality and reducing mechanical complexity.
Implementation Method 1
a light shielding member that is disposed within the air space, in which the light shielding member includes a light shielding region which is positioned outside optical paths of all effective luminous fluxes emitted from the display element and used to form the projected image, and a light transmission region which is surrounded by the light shielding region and through which the effective luminous flux is transmitted
Data Source
AI summary
The projection device includes a display element that displays an image, a projection optical system that forms an intermediate image of the image within an air space and projects the intermediate image to form a projected image, and a light shielding member that is disposed within the air space. The light shielding member includes a light shielding region which is positioned outside optical paths of all effective luminous fluxes emitted from the display element and used to form the projected image. The projection device satisfies a predetermined conditional expression.