PL70179Y1 - Printed document - Google Patents

Abstract

The printed document consisting of a base sheet on which there is a printing layer in the shape of an amplitude raster is characterized in that the printing layer between the elements of the amplitude raster (21) is in the shape of a matrix code (22), which is a matrix of 25 x 25 dots, with the size (D2) of the matrix code points (22) is equal to the size (D1) of the points of the amplitude raster elements (21).

Description

Pattern description

The subject of a utility model is a printed document. In printing technologies (such as offset, digital and other technologies), multi-image images are screened prior to printing.

Halftone is the simulation of a multi-tone image with a single-tone image in the form of a fine pattern. When viewed from a normal distance, the halftone pattern is invisible and gives the appearance of halftones. The brightness of the achieved halftones depends on the area occupied by the raster elements to the surface of the unprinted printing substrate surrounding them. The tonal value of a raster is defined as the ratio of the area covered by the raster elements to the total area. Various types of raster are known, the main of which are amplitude raster (AM screen) and frequency raster (FM screen). In an amplitude raster (AM), the centers of the raster elements are equally spaced apart on a raster grid pattern, defined by the raster frequency, usually given in Ipi (lines per inch). The individual elements of the screen vary in size, depending on the tonal value in a given area. The individual elements of the raster are made of dots, the size of which is the reciprocal of the printing resolution, usually given in dpi units (dots per inch). In printing machines, their documents are printed in such a way that a multi-tone image, defined as a matrix of dots with a certain brightness level, is converted into a raster image. Specialist raster image processors (RIP) are used for this. In standard printing systems, generating the raster image is the last element of image data processing, and the generated raster image is passed directly to the printing machine.

Various types of document security techniques are known, which make it difficult to copy documents. One of the techniques is microprinting, that is, the printing of small inscriptions in which the font height is usually around 1 mm or even several hundred micrometers. Such microscopic prints become blurred during copying, which makes it easier to distinguish the original from the copy. Microprint is, however, amenable to copying by manually modifying a copy of a document and manually generating a microscopic string before printing the copy.

Various types of graphic symbols for identifying documents are known. One of this type of symbols are matrix codes, also called 2D codes. The graphic representation of the matrix code is a matrix of symbols (usually points, squares) of different colors (usually black and white). For example, QR matrix codes (defined by the ISO / IEC 18004: 2015 standard) are known. From the publication of the international patent application WO2014014468A1 a method for generating a code such as a matrix code is known, in which the code is written in the form of a series of points, some of which are reference points and some of which are coded points. The printed dots are on the order of 10 micrometers, so microscopic print is difficult to detect and copy.

It would be desirable to develop a printed document with an alternative structure which would make the printed document difficult to copy by standard techniques.

The utility model-printed document is composed of a base sheet on which there is an amplitude screen-shaped printing layer and is characterized in that the printing layer between the amplitude screen elements has the shape of a matrix code, which is a 25x25 dot matrix, the dot size of the matrix code is equal to the point size of the amplitude raster elements.

The subject of the utility model is presented in the example in the drawing, where:

Fig. 1 shows schematically (not to scale) a side view of a document printed according to a utility model;

Fig. 2 shows an enlarged top view of a portion of a document printed according to a utility model.

A document printed according to a utility model consists of a base sheet 10 on which there is a print layer 20, for example made with ink.

Print layer 20 represents a multi-tone image by an amplitude screen 21 with a predetermined lineage, for example 180 Ipi (lines per inch) and a printing resolution, for example 2540 dpi (dots per inch). The size of the individual elements of the amplitude screen 21 depends on the tonal value of the multitone image represented by the screen at a given location. The individual elements of the amplitude screen 21 are made up of points of size D1 (conventionally measured as the diameter of the point or the length of the side of the square representing this point) equal to the inverse of the print resolution. For example, for a resolution of 2540 dpi, the size D1 of a single point is approximately 10 micrometers.

In the portion of the document shown in Fig. 2 between the elements of the amplitude screen 21, the printing layer 20 has the shape of a matrix code 22 which includes a matrix of 25x25 points, for example a QR code as specified in the ISO / IEC 18004: 2015 standard. The size D2 of the individual points of the QR code 22 (measured in the same way as the point size of the raster elements) is equal to the size of the single point forming the elements of the amplitude raster 21.

An overprint with such a structure and shape is an effective protection of the printed document. When you try to copy a document directly using standard copying devices, the scanned resolution of which (e.g. 600 dpi) is usually lower than the resolution of printing machines (e.g. 2540 dpi), the dots of the screen are blurred, and therefore the matrix code printing will be distorted on the copy of the document. Conversely, trying to make a copy by scanning the document on a high-resolution scanner and then manually editing the matrix code will be time consuming. For example, if a document has a print size of 100 x 100 mm and the size of the printed matrix code is 250 x 250 micrometers, such a document can accommodate 100 / 0.25 x 100 / 0.25 = 160,000 matrix codes. Detecting the position of the matrix code would therefore require analyzing 160,000 points of the image to identify the area in which the code is located.

In addition, scanning a document would require very high mechanical precision of document positioning, because a slight shift of the black and white dot grid printing (for example, by 5 micrometers for the print resolution and the 2540 dpi scanner) will cause the scanned image to have gray dots instead of black and white dots because there will be half the white point and half the black point for each scan point.

Claims (2)

Protective disclaimer 1. A printed document composed of a base sheet on which there is an amplitude screen-shaped printing layer, characterized in that the printing layer (20) between the elements of the amplitude screen (21) has the shape of a matrix code (22), which is a 25x25 dot matrix, the point size (D2) of the matrix code (22) being equal to the point size (D1) of the amplitude screen elements (21).