Projection Lens with Aspheric Groups for Distortion Control
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Solution Overview
Problem
Wide-angle projection lenses suffer from aberrations such as distortion and field curvature, leading to poor image quality in projection devices, which existing methods have not adequately addressed.
Innovation Solution
A projection lens configuration comprising a first lens group with spherical and aspheric lenses forming an intermediate image, followed by a second lens group with spherical and aspheric lenses for correction and magnification, and a planar reflector for projecting the image onto a screen, ensuring minimal distortion and high image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a wide-angle projection lens is used to shorten the projection distance and obtain a large-size image, then the projection distance is reduced and image size is increased, but various aberrations such as distortion and field curvature occur, leading to poor image quality
Solution Approach 1:
The projection lens is divided into multiple lens groups (first lens group with positive refractive power and second lens group with negative refractive power) and aspheric lenses, allowing each segment to correct specific aberrations while maintaining the overall wide-angle function. This segmentation enables independent optimization of distortion correction and field curvature correction.
Solution Approach 2:
Aspheric lenses are introduced into the projection lens system to replace traditional spherical lenses. The aspheric surfaces provide additional degrees of freedom for correcting aberrations, particularly distortion and field curvature, while maintaining the wide-angle field of view and short projection distance capability.
2Length of moving object
If multiple reflectors are used to shorten the projection distance, then the projection distance is reduced, but the device complexity increases
Solution Approach 1:
The patent replaces the mechanical reflector-based light path folding system with an all-transmission optical system using lens groups. This substitution eliminates the complexity of multiple reflector alignments and mechanical adjustments while achieving the same projection distance reduction through the optical power distribution in the lens groups.
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 achieves a pincushion-like light spot with distortion less than 1.5%, resulting in almost no distorted images with improved imaging quality, allowing for a shorter projection distance while maintaining a large-size image.
Implementation Method 1
The image beam passes through the first lens group to form an intermediate image
Implementation Method 2
the planar reflector is configured for reflecting the image beam from the second lens group
Data Source
AI summary
A projection lens provided is for projecting an image beam. The projection lens is disposed on a transmission path of the image beam and includes a first group of lenses and a second group of lenses. The first group of lenses includes a first spherical lens and a first aspheric lens. After the image beam passes through the first group of lenses, an intermediate image is formed between the first group of lenses and the second group of lenses, in which the first aspheric lens is the lens in the first group of lenses closest to the second group of lenses. A projection device using the projection lens is also provided. The projection device further includes a planar reflector on the transmission path of the image beam.