Safety paper with optical invisible watermarks

A safety paper, invisible technology, applied in papermaking, textile and papermaking, fiber raw material processing and other directions, can solve problems such as incompatibility, achieve good safety characteristics, good invisible effect, and easy identification.

Active Publication Date: 2012-04-18
SUZHOU UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For packaging and printing products, the image seen is reflective and there will be no see-through backlight. Th

Method used

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  • Safety paper with optical invisible watermarks
  • Safety paper with optical invisible watermarks
  • Safety paper with optical invisible watermarks

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach 1

[0065] This embodiment discusses the case when the host image is a holographic image. See Figure 5 , Figure 5 It is a schematic diagram of the surface structure of the safety paper according to the first embodiment of the present invention. The surface of the security paper includes a host image 10 and a watermark image 11. In the present invention, the so-called host image refers to the main image that the human eye sees at the general incident light angle when observing the surface of the security paper; the so-called watermark image refers to the human eye when observing the surface of the security paper, An image that cannot be seen under the general incident light angle, but needs to pass glancing light, and can only be seen at a special observation angle. The pixel 101 constituting the host image 10 is an O-shaped grating with a period of 1 μm, and the orientation angle of the grating line of the O-shaped grating in a pixel 101 is Pixels 101 formed by the O-shaped gra...

Embodiment approach 2

[0073] The second embodiment discusses the situation when the host image is a diffracted light-varying image. In this embodiment, the pixels of the host image are also O-shaped gratings, that is, a grating with a grating period between 800 nm and 10 um. The arrangement rule of the O-shaped grating is as follows: the pixel dots formed by the O-shaped grating are continuous in each row, and there is an interval between the rows, and the width of the interval is the same as the width of a pixel, which is 20 μm-80 μm. The O-shaped grating in each pixel is an orthogonal grating formed by two exposures. The gratings in all pixels are the same, that is, the grating period and the orientation angle are the same. The host image with this kind of grating as the pixel point has a rainbow effect on the surface.

[0074] The characteristics of the watermark image in this embodiment and the embedding relationship between the watermark image and the host image are the same as those in the first...

Embodiment approach 3

[0076] The third embodiment discusses the situation when the host image is another diffracted light-variable image. In this embodiment, the pixels of the host image are also O-shaped gratings, that is, a grating with a grating period between 800 nm and 10 um. The arrangement rule of the O-shaped grating is as follows: the pixel dots formed by the O-shaped grating are continuous in each row, and there is an interval between the rows, and the width of the interval is the same as the width of a pixel, which is 20 μm-80 μm. The period of the O-shaped grating in each pixel is randomly distributed, and the O-shaped grating contained in the pixel points in each row has a fixed orientation angle The orientation angle of the O-shaped grating in the row and the row has a fixed angle difference, from 0→180 degrees, and then from 180→0 to cyclically accumulate the assignment. For example, the orientation angle of the O-shaped grating of all pixels in the first row is 1 degree, then the se...

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Abstract

The invention relates to safety paper with optical invisible watermarks. According to the safety paper, sub-wavelength gratings are adopted as pixels of a watermark image. Therefore, the image can only be observed in a special glancing angle when glancing lights incidence exists. According to the invention, reflective optical watermarks are realized, the production requirements of optical watermarks are improved, the difficulty of watermark image imitation is greatly increased, and the observability of the watermarks is simplified. The watermark can be observed under a common light source without an additional special tool. Therefore, the safety paper with the optical invisible watermark has a wide application field.

Description

Technical field [0001] The invention relates to the field of optical anti-counterfeiting, in particular to a security paper with optically invisible watermark formed. Background technique [0002] Watermark manufacturing technology is an ancient technology. It uses special technology to make the paper fiber uneven density and form different thicknesses in the papermaking process. The light can show patterns and graphics with scattered light and dark and distinct levels. Watermarks are widely used on banknote paper, including fixed watermarks, semi-fixed watermarks and full-page watermarks. A full-page watermark is to cover the entire banknote paper with watermark patterns. Fixed watermark is to set a watermark pattern on a fixed part of the banknote. The semi-fixed watermark is a track where the fixed watermark is continuously shifted and displayed in a certain area of ​​the banknote, thereby resulting in a continuous multi-shot effect. There are many types of watermark patter...

Claims

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Application Information

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IPC IPC(8): D21H21/48
Inventor 陈林森温源周小红魏国军浦东林胡进朱鹏飞刘晓宁杨颖申溯
Owner SUZHOU UNIV
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