Micro-LED Display Unit with Quantum Dot Wavelength Conversion

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Solution Overview

Problem

Current projection devices using micro-LEDs face challenges in size reduction and image quality due to complex light alignment and stray light issues, particularly when the distance between micro-LEDs is less than 5 microns, leading to difficulties in manufacturing small-size full-color panels and compromising image contrast.

Innovation Solution

A display unit comprising a first display panel, a wavelength conversion element with quantum dot material, and a second display panel, along with a light combining element, which eliminates the need for an X prism light combining system, allowing for a simpler structure, reduced stray light, and enhanced image quality by converting and combining color lights effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If an X prism light combining system is used to combine light from multiple micro-LED display panels, then color light combination is achieved, but the structure becomes complex and stray light increases, affecting image contrast

Engineering Contradiction:
Improvelight combining system structureVSAvoidstray light
Core Design Contradiction:
Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the wavelength conversion function from the complex X-prism light combining system. By placing a wavelength conversion element (quantum dot film) directly on the micro-LED display panel, the conversion of blue light to green light is achieved at the source, eliminating the need for separate green light paths and reducing the overall system complexity and potential stray light paths.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the light combining and wavelength conversion functions into a single integrated structure. The wavelength conversion element is positioned on the display panel surface, combining the functions of color conversion and light guidance, thereby simplifying the optical system and reducing the number of separate optical components that could generate stray light.

Inventive Principle:
Principle #5Merging (Combining)

2Volume of moving object

If the distance between micro-LEDs is reduced to less than 5 microns to achieve small-size panels, then device size is reduced, but manufacturing complexity increases significantly

Engineering Contradiction:
Improveprojection device sizeVSAvoidmicro-LED chip transfer and bonding
Core Design Contradiction:
Volume of moving objectVSEase of manufacture

Solution Approach 1:

The patent introduces a wavelength conversion element (quantum dot film) as an intermediary layer on the micro-LED display panel. This intermediary serves multiple functions: converting blue light to green light, filling gaps between closely spaced micro-LEDs, and simplifying the manufacturing process by enabling full-color display with fewer direct LED chips, thereby making small-size manufacturing more feasible.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If micro lenses or reflectors are used to reduce the light emitting angle of micro-LED beams, then light direction is improved, but the minimum light emitting half angle remains about 20 degrees, causing total reflection in the X prism system

Engineering Contradiction:
Improvelight beam direction controlVSAvoidoptical system alignment
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent addresses the light emitting angle problem by adding a wavelength conversion dimension rather than relying solely on optical shaping. The quantum dot conversion layer converts blue light to green light, effectively creating a new optical path dimension that bypasses the need for precise angular control of green light, thereby simplifying alignment requirements.

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

The solution enables a small-size projection device with improved image quality and reduced stray light, simplifying the structure and alignment of color lights, thereby enhancing contrast and overall image performance.

Implementation Method 1

A quantum dot conversion material is disposed on the conversion region. Part of the first color light is converted into a third color light after passing through the conversion region

Methodology Applied
Scientific EffectQuantum dot wavelength conversion: Photoluminescence

Data Source

PatentEP3985434B1Display unit and projection device
Publication Date: 2025.01.08 CORETRONIC CORPORATION
  • EP3985434B1 patent drawingFigure 1~2B
  • EP3985434B1 patent drawingFigure 2C~3

AI summary

The disclosure provides a display unit and a projection device. The display unit includes a first display panel having first light emitting elements configured to provide a first color light, a wavelength conversion element located on a transmission path of the first color light and having a conversion region and a non-conversion region, a second display panel having second light emitting elements configured to provide a second color light, and a light combining element. A quantum dot conversion material is disposed on the conversion region. Part of the first color light is converted into a third color light after passing through the conversion region, and another part of the first color light passes through the non-conversion region. The light combining element is located on transmission paths of the first color light, the second color light and the third color light and is configured to form an image beam.