Optical Anti-Counterfeiting Coating for Two-Sided Color Shift
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Solution Overview
Problem
Traditional optically variable films allow color observation only from one side due to the presence of a reflective layer, limiting the observation mode and color change.
Innovation Solution
An optical anti-counterfeiting element with a substrate having a first and second surface, where a first and second transflective coating are deposited with differing refractive index to extinction coefficient ratios, allowing for different colors and color changes when observed from each side and when tilted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a reflective layer is used in the optically variable film structure, then the color change effect is achieved, but the observation is limited to one side only
Solution Approach 1:
The reflective layer is segmented into two separate transflective coatings (first and second) positioned on opposite sides of the dielectric layer. This segmentation allows each coating to contribute to the optical effect from its respective side, enabling observation from both sides while maintaining the color change functionality through the interference principle.
Solution Approach 2:
The structure employs a nested configuration where the first transflective coating, dielectric layer, and second transflective coating are sequentially deposited to form an integrated optically variable coating system. This nested arrangement allows the light to interact with multiple layers in sequence, creating the desired optical effects from both sides.
2Adaptability or versatility
If a traditional optically variable film structure is used, then the color change along with observation angle is achieved, but the white color of the reflective layer can only be observed from one side
Solution Approach 1:
Different transflective coatings with specifically tailored optical properties are applied to different sides of the dielectric layer. The first and second transflective coatings have different refractive index to extinction coefficient ratios, allowing each side to display optimized color characteristics and brightness when observed from its respective side, thereby preventing loss of color information.
3Adaptability or versatility
If the ratio of refractive index to extinction coefficient of the transflective coatings is made different, then distinct colors from each side are achieved, but the manufacturing precision requirement increases
Solution Approach 1:
The invention specifies different ratios of refractive index to extinction coefficient for the first and second transflective coatings as a key parameter change. This parameter differentiation enables the distinct color display from each side. The patent provides guidance on selecting appropriate materials and thicknesses to achieve the desired optical effects while managing manufacturing complexity.
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
Enables two-sided observation with distinct colors and color changes, enhancing anti-counterfeiting features by providing a dynamic and stereoscopic effect.
Implementation Method 1
a first transflective coating, a dielectric layer and a second transflective coating which are sequentially deposited on the first surface
Implementation Method 2
a ratio of a refractive index of the first transflective coating to an extinction coefficient of the first transflective coating is different from a ratio of a refractive index of the second transflective coating to an extinction coefficient of the second transflective coating
Implementation Method 3
the principle of a 'Fabry-Perot' interferometer
Implementation Method 4
the principle of a 'Fabry-Perot' interferometer and a structure of an 'absorbing layer/a dielectric layer/a reflective layer' are used, so as to form an optically variable coating with a color changing along with the change of an observation angle
Data Source
AI summary
The disclosure provides an optical anti-counterfeiting element (1) and an optical anti-counterfeiting product (0), which belong to the technical field of optical anti-counterfeiting. The optical anti-counterfeiting element includes: a substrate (2) having a first surface (21) and a second surface (22) opposite each other, at least a partial region of the substrate is transparent; and a first transflective coating (31), a dielectric layer (32) and a second transflective coating (33) which are sequentially deposited on the first surface, wherein a ratio of a refractive index to an extinction coefficient of the first transflective coating is different from a ratio of a refractive index to an extinction coefficient of the second transflective coating. When observed from the first surface, the optical anti-counterfeiting element appears in a relatively bright first color; when observed from the second surface, the optical anti-counterfeiting element appears in a relatively bright second color.