LED Detection via Optical Bandpass Filtering

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Solution Overview

Problem

Conventional enhanced vision systems, such as those using forward looking infrared (FLIR), are ineffective in detecting light emitting diodes (LEDs) as they do not generate an IR spectrum component, making it difficult to navigate in inclement weather or low visibility conditions where LEDs are used, such as in aviation.

Innovation Solution

A camera system employing optical bandpass filters and a processor to process images, generating a visible image of LEDs by reducing background clutter and enhancing their visibility, even through turbid media, by leveraging the visible spectrum and using a combination of ultraviolet, visible, and infrared filters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional forward looking infrared (FLIR) systems are used to detect light sources, then infrared spectrum detection is achieved, but detection of LED light sources is ineffective

Engineering Contradiction:
Improvedetection capabilityVSAvoidspectrum coverage
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The system segments the electromagnetic spectrum detection into multiple specialized sensors: one for infrared spectrum and another for visible spectrum. This allows each sensor to be optimized for its specific wavelength range, enabling simultaneous detection of both IR-emitting sources and LED sources that only emit in the visible range.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The enhanced vision system achieves multi-functionality by integrating multiple sensor types (infrared and visible spectrum sensors) and multiple detection modes. The system can detect various light sources including conventional IR-emitting sources, LED sources, and combinations thereof, making it universally applicable to different lighting conditions and source types.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If conventional enhanced vision systems detect only IR component, then thermal imaging is effective, but visible range light sources like LEDs remain undetected

Engineering Contradiction:
Improvethermal detection reliabilityVSAvoidvisible light information
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The system separates the detection functions into distinct sensor modules: one dedicated to infrared/thermal detection and another to visible spectrum detection. This segmentation ensures that thermal detection reliability is maintained while simultaneously capturing visible light information that would otherwise be lost.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system merges the outputs of infrared sensors and visible spectrum sensors into a unified enhanced vision display. This combination allows the system to present both thermal and visible light information simultaneously, providing comprehensive situational awareness without losing information from either detection modality.

Inventive Principle:
Principle #5Merging (Combining)

3Use of energy by moving object

If LEDs are used for lighting purposes, then efficiency and longevity are improved, but IR spectrum component is not generated

Engineering Contradiction:
Improveenergy efficiencyVSAvoidIR radiation absence
Core Design Contradiction:
Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The system converts the limitation of LEDs (not emitting IR radiation) into a beneficial detection opportunity by using visible spectrum sensors specifically tuned to detect LED emission wavelengths. This allows the system to effectively detect LED sources that would be invisible to conventional IR-only systems, turning the spectral difference into a detection advantage.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system changes the detection parameter from infrared wavelength to visible spectrum wavelength. By adjusting the sensor's operational wavelength to match LED emission characteristics, the system can detect LED sources efficiently, complementing the energy efficiency benefits of LED lighting with corresponding detection capabilities.

Inventive Principle:
Principle #35Parameter changes

4Measurement precision

If visible spectrum detection is added to enhance LED detection, then LED visibility is improved, but system complexity increases

Engineering Contradiction:
ImproveLED detection precisionVSAvoidmulti-sensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system segments detection functions into separate specialized sensors, which simplifies the design and processing for each individual sensor while achieving comprehensive detection capability when combined. Each sensor can be optimized independently for its specific wavelength range, reducing overall system complexity through functional separation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system adds a new detection dimension (visible spectrum) alongside the existing infrared detection dimension. This dimensional expansion allows simultaneous detection of different light source types without requiring complex modifications to existing IR sensors, maintaining relative system simplicity while enhancing detection capabilities.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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

Enables the detection and enhancement of LEDs in adverse weather conditions, allowing pilots to navigate safely by overlaying the detected LEDs on a heads-up display, even when they are not visible to the naked eye or through conventional image processing.

Implementation Method 1

A camera system employing optical bandpass filters and a processor to process images, generating a visible image of LEDs by reducing background clutter and enhancing their visibility

Methodology Applied
Scientific EffectOptical bandpass filtering: Filter (optical)

Implementation Method 2

A camera system employing optical bandpass filters and a processor to process images, generating a visible image of LEDs

Methodology Applied
Scientific EffectPhotoelectric detection: Photoelectric Effect

Data Source

PatentEP3350986B1Systems and methods for detecting light sources
Publication Date: 2021.06.16 ELBIT SYSTEMS OF AMERICA LLC
  • EP3350986B1 patent drawingFigure 1~2
  • EP3350986B1 patent drawingFigure 3~4
  • EP3350986B1 patent drawingFigure 5

AI summary

A method for detecting light sources. The method includes capturing an image including a sub-infrared light emitter, applying a filter to a pixel of the captured image to isolate a signal strength of a range of frequencies, and comparing the signal strength of the filtered pixel to an expected signal strength of a background spectra for the range of frequencies. As a result of a difference between the signal strength of the filtered pixel and the expected signal strength exceeding a predetermined threshold, the method includes identifying the pixel as corresponding to a light emitter. As a result of the difference between the signal strength of the filtered pixel and the expected signal strength not a predetermined threshold, the method includes identifying the pixel as not corresponding to a light emitter.