OLED NVIS Display Red Light Suppression

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Solution Overview

Problem

Current Night Vision Imaging System (NVIS) devices using LCDs with LED backlights face challenges in achieving dual mode lighting systems, particularly in reducing red color emission for NVIS mode, due to size constraints and issues with uniformity and backlight bleeding, which affects image quality and accuracy in military operations.

Innovation Solution

The development of OLED-based displays that utilize a combination of green and blue OLEDs with peak wavelengths in specific ranges, along with microcavities and red-blocking filters, to minimize red light emission and achieve the NVIS white spectrum, enhancing image quality and allowing for thinner dual mode backlights.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If LCDs with LED backlights are used for NVIS devices, then dual mode lighting can be achieved, but red color emission cannot be sufficiently reduced and backlight bleeding occurs

Engineering Contradiction:

Improvedual mode lighting capabilityVSAvoidred color emission

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent divides the backlight system into multiple independent OLED modules with different peak wavelengths (e.g., 450nm blue, 530nm green, 610nm red). Each module can be independently controlled to emit or not emit light, enabling dual mode operation while precisely controlling red emission levels to meet NVIS requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different characteristics to different parts of the display system by using OLEDs with specifically tuned peak wavelengths for different color regions. The red OLEDs are optimized with peak wavelengths between 610-650nm to provide necessary red content for daylight mode while naturally reducing emission in the problematic 650nm+ range, achieving local spectral optimization.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If LCDs with LED backlights are used, then dual mode lighting is possible, but image quality and accuracy are degraded due to backlight bleeding

Engineering Contradiction:

Improvedual mode lighting capabilityVSAvoidimage quality and accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

By segmenting the backlight into independent OLED modules, the patent eliminates the backlight bleeding problem inherent in LCDs. Each OLED module is self-emissive and can be precisely controlled, ensuring that light is emitted only from intended pixel locations without spreading to adjacent areas, thereby improving image quality and accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces the mechanical/optical system of LCDs (which rely on liquid crystal modulation of backlight) with a direct emissive OLED system. This substitution eliminates the need for liquid crystal layers and associated optical components that cause backlight bleeding, directly improving image precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Object-generated harmful factors

If red light emission is reduced for NVIS mode, then NVIS image quality improves, but daylight mode color saturation may be compromised

Engineering Contradiction:

Improvered color emissionVSAvoidcolor saturation

Core Design Contradiction:

Object-generated harmful factorsVSIllumination intensity

Solution Approach 1:

The patent implements dynamic control of red OLED emission intensity based on operating mode. In NVIS mode, red OLEDs are driven at reduced intensity or turned off to minimize 650nm+ emission. In daylight mode, red OLEDs operate at full intensity to provide saturated colors. This dynamic adjustment allows the system to optimize for either NVIS compatibility or color saturation as needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameters of the red OLEDs depending on mode requirements. By adjusting drive current, pulse width modulation duty cycle, or activation state of red OLED modules, the system can control the amount of red light emitted to match either NVIS specifications or full-color display requirements, maintaining color saturation in daylight mode while reducing harmful emission in NVIS mode.

Inventive Principle:

Principle #35Parameter changes

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 OLED-based displays significantly improve NVIS image quality by reducing red color output, enabling crisper and more precise images, especially in military applications, and allow for thinner dual mode backlights, enhancing operational efficiency.

Implementation Method 1

OLEDs make use of thin organic films that emit light when voltage is applied across the device

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

One application for phosphorescent emissive molecules is a full color display

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS9165984B2OLEDs for use in NVIS capable devices

Publication Date: 2015.10.20 UNIVERSAL DISPLAY CORP

AI summary

A device is provided with a first OLED having a peak wavelength in the range 500-600 nm and a second OLED having a peak wavelength in the range 400-500 nm. Less than 2% of the light emitted by the first OLED has a wavelength of 650 nm or longer and less than 2% of the light emitted by the second OLED has a wavelength of 650 nm or longer.