Projection Lens Wavelength Filter for Color Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional projection lens units, especially wide-angle ones, impair color uniformity in projected images due to incident angle-dependent antireflection coatings, causing chromaticity differences from the center to the periphery.
Innovation Solution
A projection lens unit with a plurality of lenses coated with a first antireflection coating and a wavelength selection filter having distinct transmittance regions, where the transmittance of first light is lower in the second region than in the first region, or vice versa, to mitigate chromaticity variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a wide-angle lens group is used as a projection lens unit, then the projection angle and coverage area are improved, but color uniformity from center to periphery deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the optical properties of different regions in the projection system. Specifically, the first and second antireflection coatings are designed with different spectral characteristics - the first coating optimized for blue light and the second for red light. This allows each region of the optical path to be optimized for its specific wavelength requirements, thereby maintaining color uniformity across the entire projection area while preserving the wide-angle coverage capability.
2Use of energy by moving object
If antireflection coatings are applied to lenses, then light transmission efficiency is improved, but chromaticity variation from center to periphery increases
Solution Approach 1:
The patent employs parameter changes by varying the optical properties of the antireflection coatings across different wavelengths. The first antireflection coating is designed with specific refractive index and thickness parameters optimized for blue light transmission, while the second coating has different parameters optimized for red light. This wavelength-dependent parameter optimization ensures high light transmission efficiency for both color channels while compensating for chromaticity variations that would otherwise occur across the projection field.
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 enhances color uniformity of projected images by adjusting the transmittance of different wavelength bands, reducing the impact of incident angle on chromaticity and maintaining image brightness.
Implementation Method 1
a plurality of lenses coated with a first antireflection coating
Implementation Method 2
a wavelength selection filter having a first region in a center of the wavelength selection filter through which an optical axis passes and a second region around the first region
Data Source
AI summary
A projection lens unit of the present disclosure is a projection lens unit that enlarges and projects image light output from an image forming unit onto a projection target, the image light including first light and second light having a longer wavelength band than the first light. The projection lens unit includes a plurality of lenses coated with a first antireflection coating, and a wavelength selection filter having a first region in a center of the wavelength selection filter through which an optical axis passes and a second region around the first region. In the wavelength selection filter, a transmittance of the first light in the second region is lower than a transmittance of the first light in the first region.