Diffusing Member With Dielectric Multilayer Film for Thin Planar Lighting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing planar light source devices experience uneven brightness distribution, particularly in thinner designs, due to the layout of light sources, which is not adequately addressed by current technologies.
Innovation Solution
A diffusing member comprising a light diffusing portion with light transmissivity and diffusivity, and a light reflecting portion with specific reflectance and transmittance properties, including a microlens array and dielectric multilayer film, is used to uniformly distribute light across the plane while maintaining device thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a direct-type planar light source device is used with a light source confronting a diffusing member, then the device structure is simple and compact, but unevenness in brightness occurs due to the light source layout
Solution Approach 1:
The diffusing member is divided into multiple diffusing regions with different diffusing properties corresponding to different light source positions. Each region has optimized light diffusing characteristics to compensate for the specific layout pattern of the light sources, thereby achieving uniform overall brightness while maintaining the simple direct-type structure.
Solution Approach 2:
Different portions of the diffusing member are assigned different optical properties (diffusing coefficients, thickness variations) according to the local light source distribution. Regions receiving concentrated light from specific LED positions have enhanced diffusing capabilities, while other regions have standard properties, creating local optimization that results in global uniformity.
2Length of stationary object
If the planar light source device is made thinner, then the device compactness is improved, but the unevenness in brightness becomes more pronounced
Solution Approach 1:
The diffusing member is segmented into multiple functional layers including a light diffusing layer, a light reflecting layer, and a brightness uniformity layer. Each layer has a specific thickness and optical property optimized for its function, allowing the overall device to achieve uniform brightness with reduced total thickness compared to single-layer designs.
Solution Approach 2:
The diffusing member employs composite structure combining materials with different optical properties - transparent resin materials with specific refractive indices, diffusing particles, and reflective coatings. This composite approach enables thin-section uniform light distribution by leveraging the complementary optical effects of different materials in a multi-layer configuration.
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 resolves brightness unevenness by uniformly distributing light, ensuring consistent illuminance across the light-emitting surface, even in thinner designs, by combining light diffusivity and reflectivity properties.
Implementation Method 1
a light diffusing portion (50) that has light transmissivity and light diffusivity
Implementation Method 2
a light reflecting portion (70), of which reflectance with respect to light of a particular wavelength entering at an angle of incidence of 0° is 80% or higher
Implementation Method 3
The unit optical elements may include element faces of which a normal direction is inclined with respect to the stacking direction
Implementation Method 4
A first dielectric multilayer film (1710) according to the present disclosure is a dielectric multilayer film used in combination with at least one of a diffractive optical element and a microlens array
Data Source
AI summary
A planar light source device includes a light diffusing portion and a light reflecting portion in this order. The light diffusing portion has light transmissivity and light diffusivity. Reflectance of the light reflecting portion with respect to light of a particular wavelength entering at an angle of incidence of 0° is 80% or higher. The reflectance of the light reflecting portion with respect to at least part of light of the particular wavelength entering at an angle of incidence of which an absolute value is greater than 45° is less than 50%.