Wavelength Conversion Sheet Structure for Mini-LED Light Leakage Control
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Solution Overview
Problem
Existing backlight devices with mini-LEDs suffer from reduced brightness and contrast due to light leakage from non-driven segment regions during local dimming driving, leading to brightness deterioration and unevenness.
Innovation Solution
A lighting device featuring a wavelength conversion sheet with a transparent base material and protrusions containing wavelength conversion material on its surface, which suppresses light propagation along the principal surface direction, preventing light leakage and maintaining brightness and contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat plate-shaped wavelength conversion unit is used, then the structure is simple and easy to manufacture, but light leaks from non-driving segment regions causing brightness deterioration and contrast reduction
Solution Approach 1:
The wavelength conversion unit is divided into multiple independent wavelength conversion elements, each corresponding to a segment region. This segmentation prevents light from spreading between adjacent segments, eliminating light leakage while maintaining manufacturing simplicity through modular assembly.
Solution Approach 2:
Each wavelength conversion element is designed with specific local optical properties that control light propagation within its corresponding segment region. The local structure ensures that converted light is directed only to the intended display area, preventing cross-contamination between segments and maintaining high brightness contrast.
2Illumination intensity
If minute holes are formed in the wavelength conversion unit to inhibit light propagation, then light leakage is reduced, but unevenness in brightness occurs and wavelength conversion function is reduced
Solution Approach 1:
The wavelength conversion elements are designed with curved or spherical surfaces instead of flat surfaces with holes. This curvature naturally controls light propagation paths through geometric optics, directing light appropriately without creating the brightness unevenness and chromaticity shifts that occur with hole-based approaches.
3Object-affected harmful factors
If the wavelength conversion unit space is reduced to form holes, then light propagation is inhibited, but the wavelength conversion function is reduced causing chromaticity changes
Solution Approach 1:
Instead of controlling light propagation by reducing space in the planar dimension (creating holes), the invention controls light paths by utilizing the third dimension through curved surfaces and layered structures. This approach inhibits unwanted light propagation while preserving the full volume and quantity of wavelength conversion material needed for proper chromaticity.
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 effectively inhibits light leakage between dimming regions, maintaining brightness and contrast during partial lighting, while allowing for high-precision brightness adjustment and low power consumption.
Implementation Method 1
a wavelength conversion layer in which a plurality of protrusions containing a wavelength conversion material and having a spherical surface are arranged side by side without gaps
Data Source
AI summary
A lighting device includes a plurality of light sources arranged side by side in a plane and a wavelength conversion sheet arranged to face a light emitting surface of each of the light sources and converting a wavelength of light from the light sources, in which the wavelength conversion sheet includes a base material having transparency, and a wavelength conversion layer in which a plurality of protrusions containing a wavelength conversion material and having a spherical surface are arranged side by side without gaps on a principal surface of the base material opposite to the light sources.