Display Device Optical Member with Angle-Dependent Filter
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Solution Overview
Problem
Non-emission type display devices, such as liquid crystal display devices, face challenges in preventing the hot spot phenomenon where light is concentrated in specific areas, leading to uneven illumination and reduced display quality.
Innovation Solution
The implementation of an optical member with a support substrate, a quantum dot layer, and a filter that converts first color light into second and third color lights, along with a scattering layer and reflection sheet, to distribute light evenly and prevent hot spots by varying transmittance and reflectance based on incident angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional backlight unit with light emitting units is used, then the device structure is simple, but the hot spot phenomenon occurs causing uneven illumination
Solution Approach 1:
The optical member is segmented into multiple functional layers: support substrate, quantum dot layer, and filter layer. Each layer performs a specific function - the quantum dot layer converts light wavelengths while the filter layer selectively transmits or reflects light based on incident angle, collectively solving the hot spot problem through distributed light management
Solution Approach 2:
The filter layer exhibits angle-dependent transmittance characteristics where the transmittance varies according to the incident angle of light. This local optical property adjustment allows different regions of the backlight to be controlled differently, preventing light concentration in specific areas while maintaining overall brightness uniformity
2Illumination intensity
If the filter has high transmittance to first colour light, then light efficiency is high, but hot spot phenomenon occurs due to concentrated light in specific areas
Solution Approach 1:
The filter's transmittance parameter is made dynamic with respect to incident angle. At normal incidence (0 degrees), the filter has lower transmittance to prevent hot spots, while at oblique angles (greater than 0 degrees), the transmittance increases to maintain overall light efficiency. This parameter change based on light direction resolves the contradiction between uniformity and efficiency
3Illumination intensity
If the quantum dot layer converts first colour light to second and third colour light, then display quality improves, but the device complexity increases
Solution Approach 1:
Multiple functional layers (quantum dot layer for wavelength conversion and filter layer for angle-dependent filtering) are merged into a single integrated optical member structure. This consolidation achieves high colour quality through quantum dot conversion while managing complexity by combining multiple functions into one component rather than separate assemblies
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
This configuration enhances display quality by reducing luminance variations and increasing the effective radius of illumination, thereby preventing the hot spot phenomenon and improving contrast ratio and light efficiency.
Implementation Method 1
a quantum dot layer disposed on the support substrate and configured to convert the first colour light into second colour light and third colour light
Implementation Method 2
having a first transmittance to the first colour light having a first incident angle of 0 degrees and having a second transmittance greater than the first transmittance to the first colour light having a second incident angle greater than the first incident angle
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
A display device including an optical member (300), a display panel (100) disposed above the optical member, and a plurality of light emitting units (200) disposed below the optical member and configured to provide first colour light to the optical member, in which the optical member includes a support substrate (300-G) having upper and surfaces and overlapping the light emitting units, a quantum dot layer (300-Q) disposed on the support substrate and configured to convert the first colour light into second colour light and third colour light, and a filter (300-F) directly disposed on at least one of the upper surface and the lower surface of the support substrate, and having a first transmittance to the first colour light having a first incident angle of o degrees and having a second transmittance greater than the first transmittance to the first colour light having a second incident angle greater than the first incident angle.