NVG-Compatible LED Lighting Device With Filtered Diode Housing

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Solution Overview

Problem

Existing NVG-compatible lighting devices for flat display screens face challenges in maintaining daytime luminous efficiency and compact size due to the need for filtering red-emitting diodes, which increases the size of LEDs and reduces the number of diodes that can be used, leading to reduced light output and inefficiencies in luminous flux injection.

Innovation Solution

A lighting device with a flexible printed electronic circuit carrying first light-emitting diodes and a second filtered light-emitting diode with an optical filter, where the filter is housed in a hollow mechanism that does not exceed the height of the first diodes, ensuring efficient NVG compatibility without additional constraints on daytime lighting, and a light guide is used to illuminate the edge of the backlighting system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If NVG filters are placed on red-emitting diodes to achieve night vision compatibility, then NVG compatibility is improved, but the size of LEDs increases and the number of diodes that can be used decreases

Engineering Contradiction:
ImproveNVG compatibilityVSAvoidnumber of diodes
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies local quality by selectively placing NVG filters only on specific red-emitting diodes that would otherwise saturate night vision binoculars, while leaving other diodes unfiltered. This localized filtering approach ensures NVG compatibility where needed while preserving the total number of functional diodes in the lighting device.

Inventive Principle:
Principle #3Local quality

2Reliability

If NVG filters are placed on red-emitting diodes to achieve night vision compatibility, then NVG compatibility is improved, but the size of the lighting device increases

Engineering Contradiction:
ImproveNVG compatibilityVSAvoidsize of lighting device
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The patent implements nesting by integrating the NVG filters directly onto the diode structure, where the filter is positioned within or adjacent to the diode housing. This nested arrangement eliminates the need for separate filter components and mounting structures, thereby maintaining a compact overall device size while achieving NVG compatibility.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Volume of moving object

If the number of filtered diodes is reduced to maintain compact size, then device size is improved, but the light output of daytime backlighting decreases

Engineering Contradiction:
Improvesize of lighting deviceVSAvoidlight output
Core Design Contradiction:
Volume of moving objectVSIllumination intensity

Solution Approach 1:

The patent applies local quality by selectively filtering only the specific diodes that emit in the wavelength range that saturates night vision binoculars, while leaving other diodes unfiltered to contribute fully to daytime light output. This selective approach minimizes the impact on overall illumination intensity while achieving NVG compatibility.

Inventive Principle:
Principle #3Local quality

4Reliability

If absorbing elements are added around filtered diodes to prevent light leakage, then NVG compatibility is improved, but the spacing between diodes increases and light output decreases

Engineering Contradiction:
ImproveNVG compatibilityVSAvoidlight output
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The patent implements nesting by integrating the absorbing function directly into the diode housing or mounting structure, where the housing itself serves as the light-tight enclosure. This eliminates the need for separate absorbing elements and maintains compact diode spacing, thereby preserving light output while ensuring NVG compatibility.

Inventive Principle:
Principle #7Nested doll (Nesting)

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

This solution maintains daytime luminous efficiency and compact size by allowing for a higher number of unfiltered diodes while ensuring NVG compatibility, with the filtered diodes being fewer in number but sufficient for night lighting, thus optimizing both daytime and night vision performance.

Implementation Method 1

a second light-emitting diode (14) having an optical filter (15) thereabove, the optical filter having a spectral transmission such that the light coming from the second filtered light-emitting diode (14) is compatible with the use of night vision binoculars

Methodology Applied
Scientific EffectOptical filtering: Filter (optical)

Implementation Method 2

a light guide (10) substantially of parallelepipedic or prismatic shape, of small thickness, placed under the liquid crystal matrix (20) to be illuminated

Methodology Applied
Scientific EffectLight transmission: Optical Fibre

Data Source

PatentEP3186674B1Light-emitting diode lighting device comprising a light guide and a light compatible with the use of night vision binoculars
Publication Date: 2021.02.24 THALES SA
  • EP3186674B1 patent drawingFigure 1~3
  • EP3186674B1 patent drawingFigure 4~5

AI summary

The general field of the invention is that of lighting devices compatible with the use of night vision binoculars, said lighting device (1) comprising: a row of first light-emitting diodes (11) carried and powered by an electronic circuit (12), a mechanical part (13) on which the electronic circuit is attached; a second light-emitting diode (14) surmounted by an optical filter (15), said optical filter having spectral transmission such that the light from the second diode filtered by said filter is compatible with the use of said night vision binoculars. In the lighting device according to the invention, the mechanical part comprises at least one hollow housing (16) in which the second filtered light-emitting diode is attached, the depth of the housing being sufficient for the top part of the optical filter not to protrude beyond the top part of the first light-emitting diodes.