Compact Optical Projection Apparatus Using Folded In-Line Architecture
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Solution Overview
Problem
Existing compact optical projection systems for portable devices, such as smartphones, face challenges in reducing size and power consumption while maintaining image quality and brightness, due to the large number of components and space requirements in the illumination and projection paths.
Innovation Solution
The implementation of an in-line optical architecture that folds the light path twice, using a cover prism with a total internal reflection surface and an asymmetric reflector, along with a reverse total internal reflection (RTIR) prism, to align illumination and projection light paths, reducing the number of components and space needed, and incorporating a field lens to minimize the projection path length and height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional projection architecture with separate illumination and projection paths is used, then image projection function is achieved, but device volume and component count increase
Solution Approach 1:
The patent combines the illumination path and projection path into a single integrated optical system. The illumination source, spatial light modulator, and projection lens are arranged in an in-line configuration where the illumination path and projection path share common optical components and space, eliminating the need for separate illumination and projection optical trains.
Solution Approach 2:
Optical components in the in-line architecture serve multiple functions. For example, the projection lens also acts as a field lens for the illumination path, and the spatial light modulator serves both as an image modulator and a beam steering element. This multi-functionality reduces the total number of components needed.
2Length of stationary object
If compact optical components are used to reduce size, then device thickness is reduced, but light path alignment and optical performance become more difficult to maintain
Solution Approach 1:
The patent employs a folded in-line optical architecture where the light path is folded back on itself within the compact device thickness. By utilizing the third dimension (depth) through folding the optical path, the system achieves compact thickness while maintaining sufficient optical path length and alignment margins through precise angular control of the folded paths.
Solution Approach 2:
The illumination path and projection path are arranged asymmetrically within the in-line configuration, with optimized angular relationships between components. This asymmetric arrangement allows compact packaging while maintaining proper optical alignment and separation of light paths where needed.
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 solution achieves a more compact optical projection system with improved brightness efficiency and reduced volume, allowing for the integration of optical projectors in small form factor devices like smartphones, with a total volume of 2.1 cubic centimeters and geometric efficiency of 67-69% for LED illumination sources.
Implementation Method 1
a cover prism including a curved surface positioned to receive illumination light rays and a total internal reflection surface positioned to internally reflect the light rays
Implementation Method 2
the asymmetric reflector surface is configured to reflect the received light rays out of the cover prism at an emitter side of the cover prism
Implementation Method 3
A reverse total internal reflection (RTIR) prism is positioned between the spatial light modulator and the emitter side of the cover prism. A total internal reflection surface is configured to totally internally reflect the image light rays out of the RTIR prism into a light projection device
Data Source
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AI summary
A compact optical projection apparatus. An apparatus for light projection includes at least one illumination device; a cover prism including a curved surface positioned to receive illumination light rays and a total internal reflection surface positioned to internally reflect the light rays towards an asymmetric reflector surface positioned opposite the total internal reflection surface, the asymmetric reflector surface configured to reflect the received light rays out of the cover prism at an emitter side of the cover prism; a spatial light modulating the illumination light rays with image data to form image light rays; a reverse total internal reflection (RTIR) prism positioned between the spatial light modulator and the emitter side of the cover prism and further comprising a total internal reflection surface configured to totally internally reflect the image light rays out of the RTIR prism into a light projection device. Additional apparatus are disclosed.