Optical anti-fake element and production method thereof

Abstract

The invention provides an optical anti-fake element and a production method thereof, aiming to overcome defects that processes in the prior art are complicated and it's difficult to realize color matching due to difficulty in accurately controlling thickness of coating layers of two types of coating structures in the prior art. The optical anti-fake element comprises a substrate (1) consisting of a first surface (31) and a second surface (32). Part of the first surface (31) is of a sub-wavelength micro-relief structure while another part thereof is of a flat surface structure; a first medium layer, a second medium layer and a third medium layer are sequentially superposed on the sub-wavelength micro-relief structure and the flat surface structure; colors of the sub-wavelength micro-relief structure and the flat surface structure are the same when observed in specific viewing angle, and are different when observed in other angles.

Description

technical field [0001] The invention relates to the field of optical anti-counterfeiting, in particular to an optical anti-counterfeiting element and a preparation method thereof. Background technique [0002] Because the optically variable coating can present different colors under different viewing angles, it is easy to describe, easy to identify by the public, and cannot be imitated or copied by electronic equipment such as cameras, scanners, printers, etc., so the optically variable coating has high anti-counterfeiting ability. It is widely used in the public anti-counterfeiting of high anti-counterfeiting securities such as banknotes. [0003] In order to improve the anti-counterfeiting capability of the optically variable coating, the prior art mostly combines two optically variable coatings to achieve two optically variable effects. For example, US5766738, US6114018 and US7729026 propose interference optically variable anti-counterfeiting elements that can achieve op...

AI Technical Summary

Problems solved by technology

However, in actual production, it is usually difficult to precisely control the coating thickness of the above-mentioned interferometric optically variable anti-counterfeiting elements to meet the requirements of color matching, resulting in obvious differences in color at the designed matching angle, which affects the anti-counterfeiting effect

In addition, the two coatings cannot be obtained in one evaporation process, so it is necessary to increase the precise positioning of printing protective glue, demetallization, and secondary evaporation of optically variable coatings, which increases the complexity and cost of the process.

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