Volume Grating Optical Component for Uniform Backlight Luminance
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Solution Overview
Problem
Existing display devices using LEDs face challenges in achieving light uniformity and luminance due to high light loss through geometrical optics films, which are also limited in thickness and cost by their design.
Innovation Solution
An optical component featuring volume gratings with specific diffraction element spacings and refractive indices, arranged in rectangular arrays, to diffract monochromatic light and enhance light uniformity and luminance without the need for diffusers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If geometrical optics films (diffusers) are used to achieve light uniformity, then light uniformity is improved, but light loss increases and device thickness increases
Solution Approach 1:
The patent replaces geometrical optics films (diffusers) with volume gratings that utilize diffraction optics principles. Instead of relying on light scattering through thick diffuser materials, the invention uses periodic refractive index modulations in volume gratings to achieve light uniformity through diffraction, thereby reducing light loss and eliminating the need for thick geometrical optics films
Solution Approach 2:
The patent changes the optical mechanism from geometrical optics (scattering) to physical optics (diffraction). By introducing volume gratings with specific spacing parameters (d1 and d2) and refractive index modulations, the system achieves light uniformity through constructive and destructive interference patterns, fundamentally altering how light is manipulated to reduce losses
2Illumination intensity
If geometrical optics films (diffusers) are used to achieve light uniformity, then light uniformity is improved, but device thickness increases
Solution Approach 1:
The patent substitutes thick geometrical optics diffusers with thin film volume gratings. The volume gratings achieve light uniformity through diffraction effects within a much thinner profile, eliminating the need for multiple thick optical layers and reducing overall device thickness
Solution Approach 2:
The patent transitions from using thick layers (z-dimension) to achieve light uniformity to using periodic structures in the x-y plane with sub-wavelength spacing. The volume gratings create optical effects through in-plane periodicity rather than through-thickness propagation, enabling thin-film integration
3Illumination intensity
If LEDs are used as light sources with diffusers, then light uniformity is achieved through scattering, but light loss is large
Solution Approach 1:
The patent replaces the scattering mechanism of diffusers with the diffraction mechanism of volume gratings. The volume gratings redirect light more efficiently by utilizing interference effects, maintaining light uniformity while improving luminance efficiency and reducing overall light loss in the optical path
Solution Approach 2:
The volume gratings act as intermediary structures between the LED light source and the display panel. These gratings with specific spacing parameters (d1≈λ, d2>λ) serve as optical mediators that redistribute light intensity more efficiently than diffusers, improving the coupling between light source and display while reducing losses
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 optical component achieves improved light uniformity (up to 89.7%) and luminance (up to 9243 nit) by diffraction, reducing material and thickness while eliminating the need for diffusers, thus lowering costs.
Implementation Method 1
the first volume grating is disposed on the transparent substrate and includes a plurality of first diffraction elements which are arranged in rectangular array
Implementation Method 2
a monochromatic light having a wavelength λ ranging from 380 nm to 780 nm enters the first volume grating having a refractive index n1 and a thickness T1. The spacing between two of the plurality of first diffraction elements adjacent to each other which is defined as d1 satisfies the inequality:
Implementation Method 3
The second volume grating is disposed on the transparent substrate which is located between the first volume grating and the second volume grating. The second volume grating includes a plurality of second diffraction elements which are spaced from each other and arranged in rectangular array
Implementation Method 4
The spacing between two of the plurality of second diffraction elements adjacent to each other is larger than the spacing between two of the plurality of first diffraction elements adjacent to each other
Data Source
AI summary
An optical component includes a transparent substrate, a first volume grating and a second volume grating disposed on the transparent substrate. The transparent substrate is located between the first volume grating and the second volume grating. The first volume grating has a plurality of first diffraction elements arranged in rectangular array, while the second volume grating has a plurality of second diffraction elements arranged in rectangular array. In addition, the spacing between two adjacent first diffraction elements is larger than the spacing between two adjacent second diffraction elements.