Diffractive Surface Relief Structure for Light Outcoupling Efficiency
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Solution Overview
Problem
Existing light outcoupling systems using diffractive gratings suffer from non-uniform and non-directional light output, with solitary blazed grating grooves being inefficient for a wide range of incidence angles, leading to inferior lighting effects and low light coupling efficiency.
Innovation Solution
A diffractive surface relief structure comprising a carrier element with a plurality of consecutive diffractive surface relief forms, including blazed or slanted grating grooves, arranged to interact and enhance light directivity, allowing a wider range of incidence angles to be outcoupled to a narrower range of outcoupling angles, thereby improving coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solitary blazed grating grooves are used for light outcoupling, then the structure is simple and easy to manufacture, but the light coupling efficiency is low and the lighting effect is inferior
Solution Approach 1:
The patent combines multiple blazed grating grooves into a single integrated structure with a specific cross-sectional profile featuring multiple facets. This merging of multiple grooves into one compound structure enables simultaneous interaction with multiple incident light rays, significantly improving light coupling efficiency while maintaining manufacturing simplicity through single-step fabrication processes.
Solution Approach 2:
The invention transitions from considering individual groove profiles in two dimensions to a three-dimensional structure where multiple grooves are stacked or arranged to form a composite element. This dimensional expansion allows the structure to handle a broader range of incident angles and improve overall light outcoupling performance.
2Device complexity
If solitary blazed grating grooves are used, then the device complexity is low, but the light output is non-uniform and non-directional
Solution Approach 1:
By merging multiple grating grooves into a single integrated structure with controlled spacing and alignment, the patent achieves uniform and directional light output. The combined structure ensures that multiple incident rays interact with different facets simultaneously, producing consistent outcoupling characteristics across the light guide surface.
Solution Approach 2:
The patent applies different facet angles and orientations to different regions of the compound groove structure, optimizing light interaction locally. Each facet within the composite structure is designed with specific geometric properties to control the directionality and uniformity of outcoupled light, achieving superior illumination quality without excessive complexity.
3Illumination intensity
If blazed grating grooves are used for light outcoupling, then some light directionality is achieved, but the incidence angle selectivity is too high and most light passes through without being outcoupled
Solution Approach 1:
The compound groove structure merges multiple individual grooves with different orientations and facet angles into a single integrated element. This combination enables the structure to simultaneously capture and redirect light rays incident at various angles, broadening the effective incidence angle range while maintaining good light directivity through the coordinated action of multiple facets.
Solution Approach 2:
The patent segments the incident light spectrum and angular range into multiple interaction zones within the compound groove structure. Each segment or facet is optimized to handle specific angular ranges, and the collective action of all segments provides broad angular acceptance with maintained directionality.
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 achieves higher light outcoupling efficiency and directivity, reducing leakage and enhancing control over light distribution, suitable for various optical applications including display lighting and opto-electronic devices, with improved performance compared to solitary groove solutions.
Implementation Method 1
Light rays that pass through or reflect from such surfaces are bent as a result of diffraction. The diffraction angle depends on the light wave length λ and so-called groove 'spacing' or groove 'period' d
Implementation Method 2
Total internal reflection may occur when light arriving from material with higher refractive index with respect to the second material meets a medium boundary at an angle larger than the critical angle with respect to the normal to the surface
Implementation Method 3
When the waveguide is placed in an environment with lower refractive index the guide advantageously carries the waves according to the principles of total internal reflection
Implementation Method 4
n's and v's refer to refractive indexes of first and second media and the speed of the light in said media, respectively
Data Source
Figure 1a~1b
Figure 2~3
Figure 4a~4b
AI summary
A diffractive light outcoupling unit (404, 602, 604) for forming a part of a directive light outcoupling system comprising a plurality of diffractive outcoupling units, wherein said diffractive light outcoupling unit comprises a carrier element (401) for accommodating a diffractive surface relief pattern and transporting light, and a diffractive surface relief pattern (406, 416, 502, 504, 506, 508, 510, 702, 704, 706) comprising a plurality of consecutive diffractive surface relief forms defined on a predetermined surface of the carrier element, the diffractive surface relief pattern being arranged to couple light incident thereon via interaction involving at least two surface relief forms of said plurality of consecutive diffractive surface relief forms of said diffractive surface relief pattern so as to enhance the directivity of the light to be out-coupled through collimation, wherein a number of light rays of the incident light to be diffracted penetrate through at least the first surface relief form of said diffractive surface relief pattern comprising said plurality of consecutive diffractive surface relief forms during said interaction.