Light Emitting Device Fluorescent Layer Optical Reflection Body
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Solution Overview
Problem
Existing light emitting devices face issues with low emission efficiency and display quality due to isotropic light emission from fluorescent layers, leading to blurriness and increased power consumption, as reflected light is not efficiently output and results in reduced luminance.
Innovation Solution
A light emitting device with a fluorescent layer excited by an excitation light source, featuring a low-refractive-index material layer and an optical reflection body to control light output, along with a wavelength-selective layer to enhance emission efficiency and reduce blurriness, utilizing a structure that includes a light-absorbing layer and a scattering layer for improved light management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a shadow mask deposition method is used to form red, green, and blue pixels, then full-color display is achieved, but processing accuracy of mask and alignment accuracy between mask and substrate deteriorate, and mask size increases
Solution Approach 1:
The patent extracts the color generation function from the shadow mask deposition process and relocates it to a fluorescent layer that is deposited uniformly across the substrate. The shadow mask is replaced by a color filter layer, separating the pixel definition function (performed by TFTs) from the color emission function (performed by the fluorescent layer excited by blue EL). This eliminates the need for large, precision-critical shadow masks while maintaining full-color display capability.
Solution Approach 2:
The patent introduces a fluorescent layer as an intermediary between the blue light-emitting EL layer and the color filter layer. This fluorescent layer converts blue light into red, green, and blue light through photoluminescence, serving as a mediator that enables color generation without requiring precision shadow mask deposition. The fluorescent layer is deposited uniformly and then patterned through the color filter, simplifying the manufacturing process.
2Area of stationary object
If mask size is increased to cover large-size substrates, then full substrate coverage is achieved, but mask production and processing difficulty increases due to thin metal film structure
Solution Approach 1:
The patent removes the shadow mask from the manufacturing process entirely and replaces it with a color filter layer deposited after uniform fluorescent material deposition. This eliminates the need to manufacture and process large-size shadow masks, transferring the patterning function to the color filter deposition process which can be performed more easily on large substrates.
Solution Approach 2:
Instead of depositing different colored materials through a shadow mask in a sequential process, the patent inverts the approach by first depositing a uniform fluorescent layer and then using a color filter to define the pixel colors. This reverse sequence simplifies the manufacturing process for large substrates by eliminating the need for large, complex shadow masks.
3Manufacturing precision
If insulating layer width is increased to prevent light mixing between pixels, then color mixture is prevented, but pixel area for light emission decreases
Solution Approach 1:
The patent replaces the mechanical approach of using wide insulating layers to prevent light mixing with an optical approach using a color filter layer. The color filter layer selectively transmits and blocks specific wavelengths, achieving color separation through optical properties rather than physical distance. This allows for narrower insulating layers while maintaining color purity, thereby increasing the light-emitting area and luminance.
4Ease of manufacture
If deposition is performed from lower position toward upper position, then organic layer formation is achieved, but mask flection occurs in central portion when substrate and mask sizes are increased
Solution Approach 1:
The patent removes the shadow mask from the deposition process and replaces it with a color filter layer deposited after uniform fluorescent material deposition. This eliminates the mask flection problem entirely, as the color filter is deposited after the fluorescent layer in a process that does not require large, suspended masks. The patterning is achieved through the color filter deposition rather than through shadow mask blocking during deposition.
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 significantly increases the output luminance and reduces power consumption by efficiently directing fluorescence to the outside while minimizing blurriness, achieving higher emission efficiency and improved display quality.
Implementation Method 1
a fluorescent layer that emits fluorescence by using excitation light
Data Source
AI summary
A light emitting device includes an excitation light source element that emits excitation light; a substrate that faces the excitation light source element; a fluorescent layer located on the substrate, the fluorescent layer being excited by the excitation light to emit fluorescence; an optical reflection body disposed on a side surface of the fluorescent layer, the side surface extending in a direction parallel to a stacking direction of the substrate and the fluorescent layer; and a low-refractive-index material layer disposed between the fluorescent layer and the substrate, the low-refractive-index material layer having a refractive index lower than that of the substrate.