Multi-Channel Optics for Anisotropic Projection Depth of Field
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Solution Overview
Problem
Projection displays face challenges in achieving high projection brightness while maintaining a direction-dependent depth of field that aligns with image features, particularly in applications where the projection surface is inclined or curved, leading to blurring issues due to varying distances within the image.
Innovation Solution
A projection display system with multi-channel optics is designed, where channels are arranged in an elongate array to match elongated image features, allowing for anisotropic blurring behavior. This system adjusts the aperture based on image content, providing a larger aperture along image features and a smaller aperture orthogonally, ensuring high brightness and sufficient depth of field without sacrificing sharpness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a higher f-number is used to achieve a larger depth of field, then the depth of field is improved, but the light intensity decreases
Solution Approach 1:
The projection system is divided into multiple optical channels, each with its own aperture and imaging structure. This segmentation allows the system to achieve a larger effective depth of field by combining the depth of field contributions from multiple channels, while each channel can maintain a lower f-number for better light intensity.
Solution Approach 2:
Each optical channel is assigned a specific spatial frequency range and angular range, allowing different parts of the system to have different aperture characteristics optimized for their specific function. The aperture distribution across channels is non-uniform, with each channel having an aperture size matched to its spatial frequency bandwidth requirements.
2Illumination intensity
If the aperture is increased to improve projection brightness, then the light intensity is improved, but the depth of field decreases
Solution Approach 1:
The total aperture is segmented across multiple optical channels rather than using a single large aperture. This allows the system to achieve high projection brightness by combining light from multiple channels while maintaining a large effective depth of field through the multi-channel architecture.
Solution Approach 2:
The system transitions from a single-aperture approach to a multi-channel aperture distribution in spatial frequency space. By distributing the aperture across multiple channels with different spatial frequency assignments, the system achieves both high brightness and large depth of field simultaneously.
3Length of moving object
If regularly arranged optical channels are used for miniaturization, then the construction height is reduced, but the depth of field becomes symmetrically designed and cannot be optimized for specific image features
Solution Approach 1:
The optical channels are arranged in an asymmetric, elongate configuration rather than a symmetric regular array. This asymmetric arrangement allows the depth of field to be optimized for specific image feature orientations (e.g., elongated features) while maintaining miniaturization benefits.
Solution Approach 2:
Different regions of the optical channel array are optimized for different functions: some channels handle higher spatial frequencies with smaller apertures, while others handle lower frequencies with larger apertures. This local optimization allows adaptation to specific image content requirements while maintaining compact dimensions.
4Adaptability or versatility
If the projection surface is inclined or curved, then the adaptability to different surfaces is improved, but the distance variation causes blurring beyond the depth of field tolerance
Solution Approach 1:
The projection system uses multiple optical channels, each projecting a portion of the overall image. This segmentation allows different regions of the image to be optimized for different distances and angles, compensating for inclined or curved projection surfaces and maintaining sharpness across the entire image area.
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 combines high projection brightness with directional depth of field, maintaining image sharpness even with significant variations in projection distance, particularly useful for inclined or curved surfaces, by aligning the anisotropic aperture with image features, thus minimizing blurring effects.
Implementation Method 1
The multi-channel optics are configured to image an associated sub-area of the imaging device through a separate optical channel for each channel, in such a way that the images of the individual images combine to form an overall image on a projection surface
Data Source
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Figure 2A~2C
Figure 3A~3C
AI summary
The invention relates to a projection display equipped with an image generator (30), which is designed to generate individual pictures in a distribution of sub-areas (33-1 to 33-7) of an image generation plane of the image generator (30). The projection display also comprises a multi-channel optical system (40), which is configured to image one associated sub-area (33-1 to 33-7) of the image generator (30) per channel (44-1 to 44-7) in such a way that the images of the individual pictures on a projection surface are joined to form a whole picture (5). At least some channels of the multi-channel optical system (40) are arranged along at least one curve, which is similar to at least one elongated picture feature of the whole picture (5), so that a two-dimensional anisotropic blurring behavior of each pixel is achieved. In this way, a large range of depth of field can be combined with relatively high projection brightness without having to accept losses regarding the focused display of picture features that should be projected with sufficient sharpness.