Focusing micro reflection element array optical anti-counterfeiting element and valuable article

Abstract

The invention discloses a focusing micro reflection element array optical anti-counterfeiting element and a valuable article. The optical anti-counterfeiting element comprises a transparent base layer, a micropattern array composed of micropattern units and a focusing micro reflection element array composed of focusing micro reflection element units, the micropattern array at least partially covers a first surface of the transparent base layer, the focusing micro reflection element array at least partially covers a second surface of the transparent base layer, and the distance between the focal plane of the micropattern units and the focal plane of the focusing micro reflection element units are smaller than half of the focal length of the focusing micro reflection element units; the periodicity tL of the focusing micro reflection element array and the periodicity tw of the micropattern array meet a formula (please see the formula in the specification), and / or the included angle theta between the focusing micro reflection element array and the micropattern array meets the formula -5 degrees <= theta<=5 degrees, wherein n is a positive integer. Focusing micro reflection elements with the large diameter are adopted for the optical anti-counterfeiting element, the array periodicity and the technical tolerance are large, manufacturing is easy, and the yield can be increased substantially.

Description

technical field [0001] The invention relates to the security field, in particular to an optical anti-counterfeit element of a focusing micro-reflection element array and a valuable item. Background technique [0002] Optical anti-counterfeiting elements containing microlens arrays have been widely used in the field of anti-counterfeiting of valuable items, especially in banknotes. The structure of the optical anti-counterfeiting element containing the microlens array is that the microlens array is arranged on the upper surface of the transparent base layer, and the corresponding micropattern array is arranged on the lower surface of the transparent base layer. The micropattern array is located at or near the focal plane of the microlens array. The arrangement of the pattern array and the microlens array is roughly the same, and the Moiré magnification effect of the microlens array on the micropattern array is used to realize a pattern with a certain depth of field and a uniq...

AI Technical Summary

Problems solved by technology

Since the window security thread only has adhesive glue on the back side, but no glue on the front side (the surface where the microlens array is located), the bond between the window security thread and the paper is poor, and it is easy to fall off during the circulation of banknotes

During the circulation of banknotes, pollution such as sweat stains and oil stains will change the optical characteristics of the microlens array, reducing its optical effect and losing its anti-counterfeiting function

The pattern magnification of the window security line is very sensitive to the period difference and angle between the lens array and the micro-pattern array, which requires extremely high manufacturing precision and low yield

In addition, due to the small period of the microlens array, the period of the micropattern array is also small, which limits the size of the microtext unit. The size limitation of the microtext unit directly determines the limited design of the micropattern structure.

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