Ultra-Short Throw Projector Optical Path Design
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Solution Overview
Problem
Conventional beam projectors face challenges in projecting images at ultra-short distances while maintaining image quality, correcting astigmatism and chromatic aberration, and avoiding light non-uniformity.
Innovation Solution
The design of an ultra-short throw beam projector with a panel unit, projection optical system, and reflection unit is optimized, featuring a specific arrangement of components to achieve improved imaging magnification and correction of astigmatism and chromatic aberration, along with a reflection surface configuration that minimizes light non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the projection distance is reduced to achieve ultra-short throw projection, then the device can be placed closer to the screen, but image quality deteriorates due to increased astigmatism and chromatic aberration
Solution Approach 1:
The projection optical system is divided into multiple lens groups (first, second, third lens groups) with different functions. The first lens group handles initial refraction, the second corrects aberrations, and the third provides final focusing. This segmentation allows each group to be optimized for specific tasks, enabling ultra-short throw projection while maintaining image quality by distributing the optical correction burden across multiple specialized components.
Solution Approach 2:
A reflection unit (mirror) is introduced as an intermediary component between the projection optical system and the screen. This reflection unit redirects light rays at specific angles, allowing the optical path to be folded and enabling ultra-short throw geometry while maintaining proper focal relationships. The reflection surface is specifically designed to correct astigmatism by compensating for asymmetric light path differences.
2Length of moving object
If the projection distance is reduced, then the device size can be minimized, but imaging magnification decreases
Solution Approach 1:
The projection optical system is designed with adjustable lens groups that can move along the optical axis. This dynamic adjustment capability allows the system to maintain optimal imaging magnification across varying projection distances. By dynamically repositioning the lens groups, the system compensates for the reduced projection distance and maintains adequate magnification levels.
Solution Approach 2:
The system utilizes variable focal length lenses and adjustable optical parameters to maintain imaging magnification at ultra-short distances. By changing the focal length parameters of the lens groups and adjusting the spacing between them, the system can achieve both ultra-short throw projection and adequate image magnification simultaneously.
3Length of moving object
If the projection optical system is optimized for ultra-short throw, then projection distance is reduced, but light non-uniformity increases
Solution Approach 1:
The reflection unit is designed with spatially varying surface properties to compensate for light non-uniformity. Different regions of the reflection surface have different reflective characteristics, with the central region and peripheral regions optimized for their specific light path requirements. This local optimization ensures uniform light distribution across the screen even at ultra-short projection distances where light paths are highly asymmetric.
4Manufacturing precision
If astigmatism and chromatic aberration are corrected through optical design, then image quality improves, but device complexity increases
Solution Approach 1:
Each lens group in the projection optical system is designed to perform multiple functions simultaneously. The first lens group not only refracts light but also begins aberration correction. The second lens group provides both focusing and chromatic aberration correction. The third lens group handles final focusing while contributing to astigmatism correction. This multi-functionality reduces the need for additional dedicated correction elements, thereby limiting the increase in device complexity.
Solution Approach 2:
The optical system employs asymmetric lens designs and asymmetric spacing between lens groups to efficiently correct astigmatism. Rather than using symmetric configurations that would require additional elements for correction, the asymmetric design inherently compensates for astigmatism by matching the asymmetric light paths created by the ultra-short throw geometry. The reflection unit also uses asymmetric surface profiles to provide targeted astigmatism correction.
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 enables effective image projection at short distances with enhanced imaging magnification, corrected astigmatism and chromatic aberration, and reduced light non-uniformity, providing improved user experience.
Implementation Method 1
a projection optical system configured to receive the light rays emitted from the panel unit and to refract the light rays
Implementation Method 2
a reflection unit having a reflection surface for receiving the light rays refracted by the projection optical system and reflecting the light rays
Data Source
AI summary
An image projection device includes: a panel unit configured to emit light rays; a projection optical system configured to receive the light rays emitted from the panel unit and to refract the light rays; a reflection unit having a reflection surface for receiving the light rays refracted by the projection optical system and reflecting the light rays; and a screen unit configured to display an image upon receiving the light rays reflected from the reflection surface. The panel unit, the projection optical system, the reflection unit, and the screen unit are arranged such that a distance of a shortest path among paths extending from the panel unit to the reflection unit through the projection optical system along a predetermined linear axis is longer than a distance of a longest path among paths extending from the reflection unit to the screen unit along the predetermined linear axis.