Projection Housing Microstructure for Stray Light Suppression
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Solution Overview
Problem
Image projection devices suffer from the formation of unnecessary images in the peripheral area due to stray light generated by light reflection on the housing inner surface and sunlight entering the vehicle cabin, which can interfere with the display image.
Innovation Solution
The device incorporates a housing with a plurality of columnar protrusions on its inner surface, including a second protrusion of lower height, to reflect light multiple times and reduce stray light intensity without the need for anti-reflection coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a smooth housing inner surface is used, then manufacturing is simple and cost is low, but stray light is generated causing unnecessary images in the peripheral area
Solution Approach 1:
The housing inner surface is designed with locally differentiated structures: columnar protrusions are positioned in regions where reflected light could reach the image display board, while other areas maintain smooth surfaces. This localized modification suppresses stray light generation only where necessary, without requiring complex processing of the entire housing surface.
2Object-generated harmful factors
If anti-reflection coating is applied to the housing inner surface, then stray light is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The patent replaces the chemical/optical approach of anti-reflection coatings with a mechanical structural solution: columnar protrusions are formed directly on the housing inner surface through molding or machining. This mechanical structure physically redirects light paths to prevent stray light, eliminating the need for additional coating materials and complex multi-step manufacturing processes.
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
This configuration effectively suppresses the formation of unnecessary images by significantly reducing the proportion of light that exits as stray light, thereby enhancing image clarity and reducing production costs.
Implementation Method 1
the light that has reached the inner surface can be reflected multiple times between the plurality of the columnar protrusions and between the plurality of the columnar protrusions and the second columnar protrusions, which can effectively attenuate intensity of the light
Data Source
AI summary
An image projection device is configured to project a display image on an image display board, formation of an unnecessary image in a peripheral area of the display image due to generation of stray light is effectively suppressed. A plurality of columnar protrusions is formed on an inner surface of a housing in which an image generation unit that generates the display image is housed, and a second columnar protrusion having a lower height than each of the plurality of the columnar protrusions is formed. That is, even when a part of emitted light from the image generation unit, sunlight, etc. reach the inner surface of the housing, the light that has reached the inner surface is reflected multiple times between the plurality of the columnar protrusions and between the plurality of the columnar protrusions and the second columnar protrusions, which can effectively attenuate intensity of the light.