White LED Filtering Layer for Color Gamut

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Solution Overview

Problem

White light emitting diodes (WLEDs) using phosphors have an inadequate color gamut due to undesired wavelengths in the emitted light, which can be improved by effectively removing these wavelengths, thereby enhancing the backlight effect in display devices without the need for expensive quantum dots.

Innovation Solution

A white light emitting diode with a light filtering layer, specifically a dual-band notch filtering layer or a triple-mode bandpass filtering layer, is used to filter out undesired wavelengths from the phosphor layer, improving the color gamut and backlight effect in display devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If phosphors are used as the light emitting layer in white light emitting diodes, then the manufacturing cost is reduced, but the color gamut is insufficient due to undesired wavelengths

Engineering Contradiction:

Improvemanufacturing costVSAvoidcolor gamut

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention segments the light filtering function by introducing a dual-band notch filtering layer that selectively removes specific wavelength ranges (blue and green bands) from the phosphor-emitted spectrum. This segmentation approach allows the phosphor layer to maintain its cost advantage while the filtering layer compensates for the color gamut deficiency by eliminating unwanted wavelengths and enhancing the red, green, and blue color components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dual-band notch filtering layer acts as an intermediary between the phosphor layer and the display device. It mediates the light output by selectively absorbing unwanted wavelengths and transmitting desirable ones, thereby improving the color gamut without requiring expensive quantum dot materials. The filtering layer transforms the broad-spectrum phosphor emission into a more spectrally refined output suitable for high-quality displays.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If quantum dots are used as the light emitting layer to improve color gamut, then the backlight effect is enhanced, but the manufacturing cost increases

Engineering Contradiction:

Improvecolor gamutVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention creates a functional copy of the quantum dot effect using a different approach. Instead of using quantum dots directly, it employs a dual-band notch filtering layer that replicates the spectral filtering function of quantum dots by removing unwanted wavelengths and enhancing color purity. This copying approach achieves similar color gamut performance without the high manufacturing cost associated with quantum dot materials.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The invention changes the physical and chemical parameters of the light filtering layer to achieve quantum dot-like performance. By carefully selecting the absorption characteristics, bandpass ranges, and optical properties of the filtering layer materials, the system reproduces the spectral output characteristics of quantum dots while using more cost-effective materials and manufacturing processes.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If a dual-band notch filtering layer is used to remove undesired wavelengths, then the color gamut is improved, but the device structure becomes more complex

Engineering Contradiction:

Improvecolor gamutVSAvoiddevice structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention merges the filtering function directly into the light emitting diode structure by integrating the dual-band notch filtering layer with the phosphor layer. This combined structure eliminates the need for separate filtering components in the display device assembly, thereby improving color gamut without proportionally increasing overall device complexity. The filtering layer becomes an intrinsic part of the backlight unit rather than an add-on component.

Inventive Principle:

Principle #5Merging (Combining)

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 implementation of a light filtering layer in the white light emitting diode effectively enhances the color gamut, providing a wide color gamut backlight and improved display quality, comparable to using quantum dots, while reducing manufacturing costs.

Implementation Method 1

a light filtering layer disposed on the phosphor layer, wherein the light filtering layer is a dual-band notch filtering layer or a triple-mode bandpass filtering layer

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 2

a phosphor layer disposed on the second surface of the light emitting diode chip

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS11256138B2White light emitting diode with filtering layer and backlight module and display device comprising the same

Publication Date: 2022.02.22 SUZHOU DONIS TECHNOLOGY CO LTD

AI summary

A white light emitting diode includes: a light emitting diode chip including a first surface and a second surface opposite to the first surface; an electrode disposed on the first surface of the light emitting diode; a phosphor layer disposed on the second surface of the light emitting diode; and a filtering layer disposed on the phosphor layer, wherein the filtering layer is a dual-band notch filtering layer or a triple-mode bandpass filtering layer. In addition, a backlight module and a display device using the aforementioned white light emitting diode are also disclosed.