Laser-Induced Color Flip Image via Microstructure Focusing
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Solution Overview
Problem
Existing methods for producing security elements with tilting images are complex and require multiple process steps, such as applying and removing metallization layers, which are inefficient and limited to producing only monochrome images.
Innovation Solution
A method involving a substrate with laser radiation-sensitive dye and microstructures that focus radiation to create a tilting image, where parallel laser beams are controlled for fluence and duration to generate a color effect visible within a specific viewing angle range, allowing for the production of color or gray-scale images without the need for metal layer removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a metallization layer is applied and removed through microlenses to create a tilting image, then a tilting image can be produced, but the production process becomes complex and time-consuming
Solution Approach 1:
The invention extracts and eliminates the metallization layer application and removal steps from the production process. Instead of applying metal layers and selectively removing them through microlenses, the patent uses direct laser writing on the substrate to create the tilting image, completely removing the metallization layer steps and simplifying the overall production process
Solution Approach 2:
The invention replaces the mechanical/chemical process of applying and removing metallization layers with a direct optical process. Laser beams are used to directly modify the substrate material at microlens locations, substituting the multi-step mechanical metallization process with a single optical writing step
2Manufacturing precision
If a metallization layer is removed to create a tilting image, then the image structure can be formed, but only monochrome images can be produced
Solution Approach 1:
The invention changes the fundamental parameter of image creation from removing material (metallization layer) to adding or modifying material properties directly. By using laser-induced chemical or physical changes in the substrate material, the patent enables full-color and gray-scale image production, as different laser parameters can create different color effects in the substrate
3Ease of manufacture
If parallel laser beams are used to irradiate microstructures, then color effects can be generated, but precise control of fluence and irradiation duration is required
Solution Approach 1:
The invention introduces dynamic control of laser parameters, where the fluence and irradiation duration of parallel laser beams are individually adjustable. This dynamic control allows the system to create different color effects and image structures by varying laser parameters in real-time, providing flexibility in image production while maintaining a relatively simple overall device architecture
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 method simplifies the production of security elements by reducing process steps, enabling the creation of colorful or true-color tilting images that are only visible within a predetermined viewing angle range, enhancing security features against counterfeiting.
Implementation Method 1
forming a plurality of microstructures on the substrate, the microstructures each being configured to focus radiation incident on a front surface of the substrate into the region
Implementation Method 2
the substance having a laser radiation-sensitive dye, which changes its color when irradiated with specific laser radiation
Data Source
Figure 1a~2
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AI summary
The invention relates to a method for producing a security element (12) comprising a flip image, the method comprising the following steps: providing a substrate (14) having a region with a dye that is sensitive to laser radiation. forming a plurality of microstructures (26) on the substrate (14), each microstructure (26) being formed such that it focuses radiation incident on a front face of the substrate (14) onto said region; and irradiating the microstructures (26) with a set (28) of parallel laser beams at a first angle to the substrate (14), the individual laser beams of the set (28) being arranged such that a structure of a first flip image (18) is created, which image can be discernible from the front face at a viewing angle associated with the first angle (α); wherein the dye that is sensitive to laser radiation changes its colour by irradiation with a specific laser radiation; and wherein the first flip image (18) displays a colour effect caused by the colour change.