Light Tunnel Cross-Section for Rotatable DMD Illumination
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Solution Overview
Problem
Conventional image projection apparatuses face issues with uneven illuminance and vignetting when the relative position between the light modulation element and the light tunnel changes, leading to parts of the light modulation element being excluded from the illumination area.
Innovation Solution
The design incorporates a light tunnel with a cross-sectional shape that is either square or circular, ensuring its inner surface area is sufficient to cover the entire surface of the rotatable Digital Micromirror Device (DMD), allowing for uniform illumination and preventing vignetting even when the DMD is rotated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the light tunnel is designed with a rectangular cross-section matching the 4:3 aspect ratio of the projection image, then the illumination is optimized for the standard projection format, but the light modulation element cannot be rotated or repositioned without causing vignetting and uneven illuminance
Solution Approach 1:
The light tunnel is designed with a circular cross-section instead of a rectangular one. This circular geometry allows the light modulation element to be rotated by any angle while remaining fully within the illumination area, as the circular boundary provides continuous coverage in all directions. This resolves the contradiction by enabling rotational adaptability without compromising illumination uniformity.
2Adaptability or versatility
If the light tunnel cross-section is enlarged to accommodate rotational movement of the light modulation element, then rotational adaptability is achieved, but the device complexity and size increase
Solution Approach 1:
The circular cross-section of the light tunnel provides a simple yet effective geometric solution that accommodates rotational movement without requiring complex adjustment mechanisms or multiple components. The circular geometry inherently provides the necessary clearance for rotation, achieving adaptability through elegant simplicity rather than structural 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
This configuration ensures that the entire surface of the DMD remains within the illumination area regardless of its rotational position, enabling continuous and efficient image generation without the need for adjustments in the apparatus's setup, allowing for flexible orientation of the projection image.
Implementation Method 1
The light tunnel makes uniform the intensity of light to be projected
Data Source
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AI summary
An image projection apparatus that generates an image based on image data and projects the image, comprises: an image generation element (31) that uses light emitted from a light source to generate an image; a holding unit (61) that rotatably holds the image generation element (31); and an illumination optical unit (20) that includes one or more optical systems (23, 24, 25) and a light tunnel (22) that is a tubular member surrounding part of a light path from the light source to the image generation element (31) and reflects the light by an inner surface thereof, and that projects the light passing through the light tunnel (22) toward an entire area of a rotatable range of the image generation element (31).