Angle-Dependent Diffusion Member for Uniform LED Backlight
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Solution Overview
Problem
Conventional downlight type system LED backlights face challenges in achieving uniform luminance and reducing thickness simultaneously, as the placement of diffusion plates and LED elements requires significant distance, leading to luminance unevenness and increased thickness, especially when the number of LED elements is reduced for cost and power efficiency.
Innovation Solution
A diffusion member comprising a first layer with light transmissivity and diffusivity, and a second layer with incident angle-dependent reflectance and transmittance, combined with a sealing material sheet containing a thermoplastic resin, is used to improve in-plane uniformity of luminance while reducing the thickness of the LED backlight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the diffusion plate is placed apart from the LED element to suppress luminance unevenness, then luminance uniformity is improved, but the thickness of the displaying apparatus increases
Solution Approach 1:
A transmission reflector is introduced as an intermediary component between the LED element and the diffusion plate. This reflector includes a reflective portion that reflects light directly above the LED element and a transmission portion that allows light to pass through, enabling the diffusion plate to be placed closer to the LED element while maintaining luminance uniformity. The reflector mediates the light path, allowing for reduced spacing without sacrificing uniformity.
Solution Approach 2:
The transmission reflector utilizes a patterned structure with reflective and transmission portions arranged in specific geometries. By designing the reflector with a pattern that matches the LED element arrangement, the system achieves luminance uniformity through spatial distribution of light paths rather than relying solely on increased vertical spacing. This dimensional approach allows closer placement of components.
2Quantity of substance
If the number of LED elements is reduced to reduce cost and power consumption, then cost and power consumption are reduced, but luminance unevenness occurs
Solution Approach 1:
The transmission reflector acts as a mediator that compensates for the increased spacing between fewer LED elements and the diffusion plate. By reflecting light from directly above the LED elements and distributing it through the transmission portion, the reflector maintains luminance uniformity even when the number of LED elements is reduced, allowing for lower cost and power consumption.
Solution Approach 2:
The transmission reflector changes the optical parameters of the system by introducing a patterned reflective and transmission structure. This structure modifies the light distribution characteristics, enabling uniform luminance to be maintained with fewer LED elements by optimizing the light paths and distribution patterns.
3Illumination intensity
If a transmission reflector is added to improve in-plane uniformity of luminance, then luminance uniformity is improved, but the thickness increases and alignment complexity increases
Solution Approach 1:
The transmission reflector is designed with a pattern that is complementary to the LED element arrangement. The reflective portion and transmission portion are configured to work together with the LED elements and diffusion plate in a multi-functional manner, improving luminance uniformity while the patterned design inherently provides alignment guidance, reducing the complexity of precise alignment during assembly.
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 enhances luminance uniformity and reduces the thickness of the LED backlight, allowing for the use of fewer LED elements and lower power consumption while maintaining high-quality display performance.
Implementation Method 1
the first layer has a light transmissivity and a light diffusivity
Implementation Method 2
in the second layer, a reflectance of light increases as an absolute value of an incident angle with respect to a first layer side surface of the second layer decreases
Implementation Method 3
a transmittance of light increases as an absolute value of an incident angle with respect to a first layer side surface of the second layer increases
Data Source
AI summary
A diffusion member includes a first layer and a second layer, in this order, wherein the first layer has a light transmissivity and a light diffusivity, in the second layer, a reflectance of light increases as an absolute value of an incident angle with respect to a first layer side surface of the second layer decreases, and a transmittance of light increases as an absolute value of an incident angle with respect to a first layer side surface of the second layer increases.