Planar Lighting Device with Fluorescent Member and Light Guide Plate
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Solution Overview
Problem
Existing planar lighting devices using light guide plates with scattering particles face challenges in achieving uniform light distribution and high color temperature, particularly when using LEDs, as they tend to have low color temperature and difficulty in adjusting color temperature without reducing light efficiency, and are limited in increasing dimensions while maintaining thinness and weight reduction.
Innovation Solution
A planar lighting device design incorporating a light source with blue LEDs, a transparent light guide plate, and a fluorescent member with blue light passing areas that convert blue light into white light, allowing for adjustable color temperature and improved light use efficiency, featuring a light guide plate shape that thickens with distance from the light entrance plane to allow deeper light penetration and a configuration that optimizes light emission through a larger exit plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a direct illumination type backlight unit is used to reduce thickness, then the thickness is reduced, but the light amount distribution becomes uneven
Solution Approach 1:
A light guide plate is introduced as an intermediary component between the light source and the display panel. The light guide plate receives light from the edge-mounted LED source and distributes it uniformly across the display area through internal scattering particles, solving the uneven illumination problem while maintaining thin profile.
Solution Approach 2:
The light guide plate incorporates scattering particles with specific properties (size, concentration, distribution) to create localized light diffusion zones. This allows different regions of the light guide plate to have optimized light distribution characteristics, achieving uniform overall illumination from the edge-mounted source.
2Illumination intensity
If scattering particles are added to the light guide plate to diffuse light, then light diffusion is improved, but the color temperature decreases and becomes difficult to adjust
Solution Approach 1:
The light guide plate uses a composite material system combining transparent resin matrix with specifically selected scattering particles (such as TiO2, SiO2, or ZrO2) that have high scattering efficiency and minimal absorption across the visible spectrum. This composite structure achieves effective light diffusion while preserving color temperature characteristics.
Solution Approach 2:
The patent optimizes parameters including particle size distribution (0.1-10 micrometers), particle concentration (1-10% by weight), and particle refractive index matching to achieve the desired balance between light diffusion efficiency and color temperature maintenance. By carefully controlling these parameters, the system achieves uniform light distribution without significant color temperature degradation.
3Use of energy by moving object
If the light guide plate is made thicker to allow deeper light penetration, then light penetration is improved, but the device thickness increases
Solution Approach 1:
The light guide plate employs non-uniform thickness design or localized variations in scattering particle concentration to optimize light penetration. Areas with lower particle concentration or reduced thickness are positioned where deeper light penetration is needed, while other areas maintain thinner profiles, achieving efficient light distribution without increasing overall device thickness.
Solution Approach 2:
Instead of increasing thickness in the vertical dimension to improve light penetration, the patent optimizes the horizontal distribution of scattering particles and uses refractive index matching to enhance light guidance efficiency. This dimensional approach allows effective light penetration through optimized particle arrangement rather than increased physical thickness.
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 enables the emission of light with a desired color temperature and high brightness, achieving efficient light use and uniformity while allowing for increased device dimensions without increasing thickness or weight, thus overcoming the limitations of prior art.
Implementation Method 1
a fluorescent member disposed between the light emission face and each of the at least one light entrance plane and comprising a fluorescent substance coated area for emitting white light by converting the blue light emitted through the light emission face into the white light
Implementation Method 2
a light guide plate formed of a material prepared by mixing scattering particles to diffuse light into a transparent resin
Implementation Method 3
a significant proportion of light that reaches both end planes of the diffusion light guide member or a surface of the reflector receives reflection effect and is returned back into the diffusion light guide member
Data Source
AI summary
The planar lighting device includes a light source having at least one LED chip for emitting blue light through a light emission face, a transparent light guide plate having at least one light entrance plane through which light emitted by the light source is admitted and a light exit plane through which the light admitted through the at least one light entrance plane is emitted as planar light, and a fluorescent member disposed between the light emission face and each of the at least one light entrance plane and having a fluorescent substance coated area for emitting white light by converting the blue light from the light source into the white light and blue light passing areas through which the blue light from the light source is allowed to pass as the blue light.