Image Display Module White Point Stability via Color Filter Transmittance Control
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Solution Overview
Problem
Existing image display devices face challenges in maintaining stable white point display due to unreliable combinations of white-light-emitting devices and color filters, particularly in achieving high white brightness and color purity.
Innovation Solution
An image display module comprising a nitride semiconductor light-emitting element with specific fluorescent materials and a color filter having blue pixels with controlled transmittance, stabilizing the chromaticity coordinates of the white point and enhancing white brightness and color purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional white-light-emitting devices and color filters are combined, then device complexity is reduced, but white point stability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the emission peak wavelength (430-450nm) and half bandwidth (30nm or less) of the blue LED, along with specific transmittance characteristics of the color filter in the 420-460nm range. These parameter specifications ensure stable white point chromaticity coordinates while maintaining a relatively simple LED-based structure.
Solution Approach 2:
The patent uses composite materials by combining a nitride semiconductor blue light-emitting element with specific fluorescent materials (yellow YAG fluorescent material and red fluorescent material) to create a white-light-emitting device with stable spectral characteristics. This composite approach ensures consistent white point stability while keeping the overall device structure manageable.
2Device complexity
If blue LED emission spectrum is broadened, then device complexity is reduced, but color purity deteriorates
Solution Approach 1:
The patent specifies precise parameter ranges: blue LED emission peak wavelength of 430-450nm with half bandwidth of 30nm or less, and color filter transmittance difference of 4% or less in the 420-460nm range. These controlled parameters achieve high color purity for blue pixels while maintaining a simple LED-based light source structure.
3Ease of manufacture
If color filter transmittance varies widely, then ease of manufacture is improved, but white brightness deteriorates
Solution Approach 1:
The patent controls the color filter's transmittance characteristics in the blue wavelength range (420-460nm) with a difference of 4% or less between maximum and minimum values. This precise parameter control optimizes white brightness by ensuring efficient blue light transmission while still allowing for practical manufacturing processes.
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 provides a stable display of white point with high white brightness and color purity by using a nitride semiconductor light-emitting element in conjunction with an Mn4+-activated red fluorescent material and a green fluorescent material, combined with a color filter that ensures minimal transmittance variation across specific wavelengths.
Implementation Method 1
a nitride semiconductor light-emitting element, as a light source, having an emission peak wavelength in a wavelength range of 240 nm to 560 nm
Implementation Method 2
an Mn4+-activated red fluorescent material having a maximum excitation wavelength in the wavelength range, an emission peak wavelength of 610 nm to 670 nm
Implementation Method 3
a green fluorescent material having an emission peak wavelength in a wavelength range of 510 nm to 550 nm
Implementation Method 4
a color filter having blue pixels in which a difference between a maximum value and a minimum value of transmittance at a wavelength range of 420 nm to 460 nm of spectral transmittance curve is 4% or less
Data Source
AI summary
An image display module includes a light emitting device including a nitride semiconductor light-emitting element, as a light source, having an emission peak wavelength in a wavelength range of 240 nm to 560 nm, an Mn4+-activated red fluorescent material having a maximum excitation wavelength in the wavelength range, an emission peak wavelength of 610 nm to 670 nm, and a half bandwidth of the emission spectrum of 30 nm or less, and a green fluorescent material having an emission peak wavelength in a wavelength range of 510 nm to 550 nm; and a color filter having a blue pixel wherein the difference between the maximum and the minimum value of transmittance at a wavelength range of 420 nm to 460 nm of the spectral transmittance curve is 4% or less.