Uneven Surface Microstructures for High Directivity Diffracted Light
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Solution Overview
Problem
Current displays used to prevent counterfeiting, such as those on securities and identification documents, face challenges in achieving high brightness and directivity of diffracted light, especially under low light conditions, which affects their visibility and effectiveness in distinguishing from printed objects.
Innovation Solution
The display features an uneven surface with alternating protrusion and depression surfaces that taper in the thickness direction, arranged at specific periods to limit reflection and enhance diffracted light emission in the oblique view direction, increasing the directivity and brightness of the diffracted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If microstructures are arranged at regular intervals in both first and second directions, then the diffracted light can be emitted in multiple directions, but the directivity of the diffracted light decreases and brightness is reduced
Solution Approach 1:
The invention segments the microstructure arrangement into two distinct directional components: the first direction (Y-direction) controls the emission angle through periodic spacing, while the second direction (X-direction) uses continuous extension to maintain brightness. This segmentation allows independent optimization of directivity and emission range.
Solution Approach 2:
The invention transitions from a two-dimensional periodic grid to a one-dimensional periodic structure extended in another dimension. By arranging microstructures periodically only in the first direction and continuously extending them in the second direction, the patent achieves directional control without sacrificing brightness.
2Illumination intensity
If the amount of incident light is small, then the display can show black color in front-view direction, but the iridescent color in oblique view direction becomes less perceptible
Solution Approach 1:
The invention applies different structural characteristics to different spatial locations: in the front-view direction, the continuous extended surfaces create strong light absorption for black color display, while in the oblique view direction, the periodic microstructures generate diffracted light with enhanced brightness. This local quality differentiation resolves the contradiction between black color display and iridescent color visibility.
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 results in a display that effectively emits diffracted light with increased brightness and directivity, improving its visibility and ability to differentiate from printed objects even under low light conditions, thus enhancing counterfeiting prevention and decorative qualities.
Implementation Method 1
diffracts the light incident on the uneven surface to emit diffracted light in an oblique view direction of the uneven surface
Implementation Method 2
The uneven structure has a property of absorbing light incident on the uneven structure
Data Source
AI summary
Each protrusion surface has a shape of a strip extending in an extension direction perpendicular to the arrangement direction. Each protrusion surface tapers toward a top section in a thickness direction of an uneven structure. Each depression surface has a shape of a strip extending in the extension direction. Each depression surface tapers toward a bottom section in the thickness direction of the uneven structure. The protrusion surfaces and the depression surfaces are arranged at a period that limits reflection of light that is incident on the uneven surface in a front-view direction of the uneven surface and diffracts the light incident on the uneven surface to emit diffracted light in an oblique view direction of the uneven surface. The uneven structure has a property of absorbing light incident on the uneven structure.