Split NVIS Filter Layout for Lower-Layer Aviation Displays
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Solution Overview
Problem
Conventional NVIS filters for aviation displays are complex and expensive due to their multi-layered structure, which impairs pilot vision and increases the cost of avionic systems.
Innovation Solution
A split NVIS filter design is implemented, comprising a first and second interference filter positioned before and after a diffuser, respectively, to reduce near-infrared and infrared wavelengths, thereby simplifying the filter structure and maintaining superior performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional NVIS filter with more than 80 coating layers is used, then infrared and near-infrared wavelengths are effectively blocked, but the filter becomes complex and expensive to manufacture
Solution Approach 1:
The patent divides the conventional single NVIS filter into two separate interference filters with fewer layers each. The first filter has a first cutoff wavelength and a second cutoff wavelength, while the second filter has a first cutoff wavelength between the first and second cutoff wavelengths of the first filter. This segmentation reduces the total number of coating layers needed in each individual filter while maintaining the overall infrared and near-infrared blocking performance.
2Object-affected harmful factors
If a conventional NVIS filter with more than 80 coating layers is used, then infrared and near-infrared wavelengths are effectively blocked, but manufacturing costs increase significantly
Solution Approach 1:
The patent divides the conventional single NVIS filter into two separate interference filters with fewer layers each. The first filter has a first cutoff wavelength and a second cutoff wavelength, while the second filter has a first cutoff wavelength between the first and second cutoff wavelengths of the first filter. This segmentation reduces the total number of coating layers needed in each individual filter while maintaining the overall infrared and near-infrared blocking performance.
3Object-affected harmful factors
If broadband emissions are present, then NVIS goggles emit bright light causing bloom effect, but the display must maintain color visibility
Solution Approach 1:
The patent applies different filtering characteristics to different wavelength ranges using two specialized interference filters. The first interference filter targets specific infrared wavelengths with its first and second cutoff wavelengths, while the second interference filter addresses near-infrared wavelengths with its first cutoff wavelength positioned between the first and second cutoff wavelengths of the first filter. This localized filtering approach selectively blocks harmful wavelengths while preserving the visible color spectrum for display.
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 split NVIS filter design achieves improved black NVIS performance with reduced material costs and maintains color accuracy across different viewing angles, meeting NVIS compliance standards while reducing complexity and cost.
Implementation Method 1
The first interference filter comprises a first cutoff wavelength and a second cutoff wavelength
Implementation Method 2
The second interference filter comprises a first cutoff wavelength. The first cutoff wavelength of the second interference filter is between the first cutoff wavelength of the first interference filter and the second cutoff wavelength of the first interference filter
Data Source
AI summary
A display includes a split night visions imaging system (NVIS) filter, including a first and second interference filter. The first interference filter is disposed between a backlight and a diffuser of the display. The second interference filter is disposed between the diffuser and an LCD stack of the display. A cutoff wavelength of the second interference filter is between cutoff wavelengths of the first interference filter.