Laminate, personal authentication medium, and method for manufacturing laminate
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Solution Overview
Problem
Hologram layers in personal verification media have limited configurational freedom due to their asperity-based image display, restricting the variety of images that can be displayed, which is a common issue in both personal verification media and diffraction layers used in other applications.
Innovation Solution
A laminate comprising an optically transmissive diffraction layer with repetitive diffraction units and an optically transmissive absorption layer, where the absorption parts overlap with diffraction elements, allowing for enhanced image configuration by controlling light absorption and emission, resulting in higher chroma levels and sharper images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a hologram layer is configured to display images based on asperities, then the image display function is achieved, but the degree of freedom in image configuration is limited
Solution Approach 1:
The invention divides the hologram layer into multiple diffraction units, each containing multiple diffraction elements. This segmentation allows independent configuration of each unit, enabling complex overall images while maintaining simplicity in individual unit design. The segmented structure provides freedom to arrange different image elements without redesigning the entire layer.
Solution Approach 2:
The invention transitions from traditional two-dimensional asperity-based hologram configuration to a three-dimensional layered structure with diffraction units arranged in both lateral and vertical dimensions. This dimensional expansion allows images to be constructed by stacking and arranging diffraction units, significantly increasing configurational freedom while maintaining manufacturing simplicity.
2Illumination intensity
If light passes through diffraction elements without absorption control, then the diffraction effect is achieved, but light mixing reduces chroma level
Solution Approach 1:
The invention extracts and removes unwanted light components by introducing absorption parts that selectively absorb light from adjacent diffraction elements. This extraction process isolates the desired diffracted light from each element, preventing color mixing and maintaining high chroma levels in the displayed image.
Solution Approach 2:
The absorption parts serve as intermediary elements positioned between diffraction units. These intermediaries selectively absorb stray light while allowing desired diffracted light to pass, thereby mediating between adjacent diffraction elements to prevent light mixing and preserve color purity.
3Manufacturing precision
If absorption parts are positioned without precise alignment to diffraction elements, then manufacturing is simplified, but positional accuracy decreases
Solution Approach 1:
The invention implements preliminary positioning by providing reference marks on the support layer before forming absorption parts. This preliminary action establishes precise alignment references that guide the subsequent formation of absorption parts, ensuring high positional accuracy without requiring complex real-time alignment procedures during manufacturing.
Solution Approach 2:
The invention uses the pattern of diffraction units as a template or copy reference for positioning absorption parts. By replicating the spatial arrangement of diffraction units in the absorption layer through the reference marks, the system achieves precise alignment automatically, simplifying the manufacturing process while maintaining high positional accuracy.
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 laminate enhances the degree of freedom in image configuration relative to the diffraction layer, achieving higher chroma levels and sharper image display, while also improving positional accuracy of absorption parts, making it difficult to counterfeit.
Implementation Method 1
a diffraction layer that is optically transmissive and includes a diffraction part configured by a plurality of diffraction units, the plurality of diffraction units being repetition of a diffraction unit in a direction of extending the diffraction layer, each diffraction unit including at least one diffraction element configured by a reflective diffraction grating
Implementation Method 2
an absorption layer that is optically transmissive and includes a plurality of absorption parts that absorb at least part of visible light
Data Source
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AI summary
A laminate includes: a diffraction layer that is optically transmissive and includes a diffraction part configured by a plurality of diffraction units, the plurality of diffraction units being repetition of a diffraction unit in a direction of extending the diffraction layer, each diffraction unit including at least one diffraction element configured by a reflective diffraction grating; and an absorption layer that is optically transmissive and includes a plurality of absorption parts that absorb at least part of visible light, the absorption layer facing the diffraction layer in a state where light passes between the diffraction layer and the absorption layer. In the laminate, the laminate has an observation side that is opposite to a side where the diffraction layer faces the absorption layer; the diffraction layer has a surface serving as a front surface on a side opposite to the surface facing the absorption layer; and in plan view perpendicular to the front surface of the diffraction layer, each of the absorption parts aligns with corresponding one of the diffraction elements.