Edge-Lit BLU with Quantum Dot Films for Wide-Gamut VR-LCDs
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Solution Overview
Problem
Conventional edge-lit BLUs in high-resolution LCD panels for near-eye displays suffer from low efficiency and limited color gamut, particularly with white LED-based systems, necessitating improved brightness and color saturation.
Innovation Solution
Incorporation of quantum dot films and optical efficiency enhancement films, including prisms and pyramids, to modify the angular beam profile and convert blue light into red and green light, combined with brightness enhancement films to enhance on-axis display efficiency and achieve a wider color gamut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional white LED-based edge-lit BLU is used, then device complexity is reduced, but color gamut is limited and on-axis efficiency is low
Solution Approach 1:
The patent employs a composite BLU structure integrating multiple functional layers: quantum dot film (for wavelength conversion), optical efficiency enhancement film with microlens array (for light collimation), and brightness enhancement film (for directional control). This composite approach achieves 12% on-axis efficiency improvement while maintaining manageable device complexity through systematic layer integration.
Solution Approach 2:
The patent modifies key optical parameters of the BLU system by introducing microlenses with specific focal lengths and densities, adjusting the quantum dot film thickness and composition, and optimizing the angular response characteristics. These parameter changes enable precise control over light distribution and efficiency without requiring complete system redesign.
2Adaptability or versatility
If conventional white LED-based BLU is used, then manufacturing is simpler, but color gamut is limited
Solution Approach 1:
The quantum dot film serves as an intermediary layer that converts blue LED light into broad-spectrum white light with enhanced color rendering. This intermediary approach enables wide color gamut (DCI-P3 coverage) while avoiding the need for complex multi-LED architectures, thus maintaining relative manufacturing simplicity.
Solution Approach 2:
The BLU is segmented into distinct functional layers: blue LED array, light guide plate, quantum dot film, optical efficiency enhancement film, and brightness enhancement film. This segmentation allows independent optimization of each layer's properties and simplifies the manufacturing process by enabling modular assembly and testing.
3Productivity
If quantum dot film and optical efficiency enhancement film are added, then color gamut and on-axis efficiency improve, but device complexity increases
Solution Approach 1:
The optical efficiency enhancement film performs multiple functions simultaneously: it acts as a collimating element via microlenses, serves as an adhesive layer bonding quantum dot and brightness enhancement films, and provides structural support. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity despite adding functional capabilities.
Solution Approach 2:
The patent merges the optical efficiency enhancement function with the adhesive bonding function into a single integrated film layer. The microlens array is formed directly on the adhesive layer, combining light collimation and structural adhesion functions. This merging approach achieves 12% on-axis efficiency gain while avoiding the need for additional separate components.
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 results in a 12% on-axis efficiency gain with a DCI-P3 color gamut, surpassing conventional white LED-based systems, and enables high-resolution LCD panels to achieve a color gamut equivalent to OLED displays.
Implementation Method 1
a light guide plate configured to receive blue light from the array of blue LEDs, guide the blue light through total internal reflection, and couple portions of the blue light guided by the light guide plate out of the light guide plate
Implementation Method 2
a quantum dot film including quantum dots configured to absorb blue light and emit red and green light
Implementation Method 3
a brightness enhancement film configured to transmit incident light within an angular range and reflect incident light outside of the angular range
Implementation Method 4
an optical efficiency enhancement film between the quantum dot film and the brightness enhancement film, the optical efficiency enhancement film configured to modify an angular beam profile of light from the quantum dot film such that the light transmitted by the brightness enhancement film has a peak intensity in a direction perpendicular to the LC panel
Data Source
AI summary
A liquid crystal display panel for near-eye display comprises a liquid crystal (LC) panel and a backlight unit (BLU). The BLU includes an array of blue light-emitting diodes (LEDs); a light guide plate configured to guide the blue light from the array of blue LEDs through total internal reflection, and couple portions of the blue light guided by the light guide plate out of the light guide plate; a quantum dot film including quantum dots configured to absorb blue light and emit red and green light; a brightness enhancement film configured to transmit incident light within an angular range and reflect incident light outside of the angular range; and an optical efficiency enhancement film configured to modify an angular beam profile of light from the quantum dot film such that the light transmitted by the brightness enhancement film has a peak intensity in a direction perpendicular to the LC panel.