LED Lighting Panel Prism Structures Optical Coupling
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Solution Overview
Problem
Existing LED-based lighting systems face issues with low optical efficiency, bulkiness, and short operating lifetimes due to high optical coupling losses, unstable materials, and wide beam angles, making them unsuitable for applications requiring specific beam angles and long-term performance.
Innovation Solution
The integration of LEDs within a lighting panel with transparent prism structures and a guide layer, along with a reflector and coating, to enhance optical coupling, reduce thickness, and control light output angles, achieving high optical efficiency and extended lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If LEDs are edge-coupled into a planar light guide to create a thin luminaire panel, then the system thickness is reduced and large area diffuse lighting is achieved, but optical coupling losses increase and optical efficiency drops to around 50%
Solution Approach 1:
A transparent adhesive layer with refractive index between 1.40 and 1.60 is introduced as an intermediary between the LED and light guide. This adhesive layer optimizes optical coupling by matching refractive indices, reducing reflection losses and improving light transfer efficiency while maintaining the thin profile of the system.
Solution Approach 2:
The patent optimizes the thickness of the light guide and adhesive layer within specific ranges (light guide: 0.5-5mm, adhesive: 10-100 micrometers). By carefully controlling these dimensional parameters, the system achieves both thin profile and high optical efficiency, resolving the contradiction between thickness reduction and coupling loss minimization.
2Illumination intensity
If acrylic (PMMA) is used as the transparent light-guide plate material due to its high optical transparency, then light transmission is maximized, but the material becomes unstable at high temperatures and high light power levels, leading to discoloration and reduced transmission over time
Solution Approach 1:
The patent employs a composite structure consisting of the light guide material combined with a transparent adhesive layer having specific refractive index properties (1.40-1.60). This composite approach allows optimization of both optical transmission and thermal stability, as the adhesive layer can be formulated to resist discoloration at high temperatures while maintaining optical clarity.
Solution Approach 2:
The patent specifies precise refractive index ranges for the adhesive layer (1.40-1.60) to optimize optical coupling and reduce stress on the light guide material. By controlling this material parameter, the system achieves high light transmission while the adhesive layer provides thermal buffering that protects against temperature-induced degradation.
3Device complexity
If the lighting panel uses a simple light guide structure without prism structures, then the device complexity is reduced, but the beam angle becomes too wide (lambertian 120° FWHM) and external beam control films are required
Solution Approach 1:
The transparent adhesive layer serves multiple functions simultaneously: it optimizes optical coupling between LED and light guide, controls the beam angle distribution, and eliminates the need for separate external beam control films. This multi-functionality reduces overall device complexity while achieving precise beam control.
Solution Approach 2:
The adhesive layer acts as an optical intermediary that modifies beam characteristics as light passes from the LED through the light guide. By selecting appropriate refractive indices (1.40-1.60), the adhesive layer naturally controls the beam angle without requiring additional optical elements, thus maintaining simplicity while achieving beam control.
4Area of stationary object
If the light guide has large average optical path lengths to achieve diffuse lighting coverage, then the illuminated area is increased, but optical losses increase due to absorption in the transparent polymer
Solution Approach 1:
The transparent adhesive layer with optimized refractive index (1.40-1.60) reduces reflection losses at interfaces, thereby minimizing optical absorption within the light guide material. This allows light to travel longer path lengths through the light guide with reduced losses, enabling large area illumination while maintaining high optical efficiency.
Solution Approach 2:
The patent optimizes the thickness of the light guide (0.5-5mm) and adhesive layer (10-100 micrometers) to balance light propagation distance with minimization of absorption losses. These controlled dimensional parameters enable sufficient light distribution across large areas while keeping optical losses acceptably low.
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
This configuration significantly improves optical efficiency, reduces system thickness, and extends the operating life of LED lighting panels by compressing light beams into narrower angles, eliminating the need for external beam control films and stabilizing the material under high temperatures.
Implementation Method 1
transparent prism structures and a guide layer, along with a reflector and coating, to enhance optical coupling
Implementation Method 2
The light 10 generated by the light source 8 then propagates within the planar light guide 9 due to the effects of total internal reflection
Implementation Method 3
a reflector and coating, to enhance optical coupling
Data Source
Figure 1~2
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AI summary
A lighting panel that provide an alternative means for producing a "spot light" like illumination from an LED is described. The lighting panel comprising a transparent substrate upon a first surface of which are mounted a plurality of transparent prism structures and upon a second surface of which is mounted a light emitting diode (LED). A transparent guide layer is arranged so as to encapsulate the light emitting diode upon the second surface such that the transparent base substrate and the transparent guide light form a composite structure for guiding light emitted from the LED. The transparent prism structures are configured to extract a first and a second light output from the lighting panel, the first and second light outputs having output angles and beam widths determined by the structure of the plurality of transparent prism structures. The lighting panels exhibit high optical efficiencies and long operating lifetimes.