LT5868B - Method of technical protection for printed products against copying - Google Patents

Abstract

The invention relates to printing technology and can be used for protection of printed products against copying. Object of the invention is pattern formation technology and patterns, printed in protected carrier. Hidden images reveal in a copy during copying. Each of the sequentially generated pictures is unique and allows for an experimental verification of the authenticity.

Description

The invention relates to processes for printing, copying, labeling or copying and printing of securities.

State of the art

There are known methods of producing a printed output that ensure that hidden images appear in the copy when such output is copied. GB8514158, GB8818431, EP0710574, DE19635761 describe drawings consisting mainly of lines with a variable angle and period of formation, which results in the appearance of a hidden image during copying. Many modern duplicators are capable of making copies that are minimally different from the original, and in such copies the sensitive images are poorly distinguished. However, the security features of this principle are present in all securities, including money notes. Many computer security programs allow you to create a "hidden image" effect, but in many cases the protective effect turns out to be quite weak. This result is due to the fact that the user, many times changing the settings of the drawing, chooses more beautiful, but does not understand what the protective effect is.

The object of the invention

Set a list of effects that cause the hidden image to appear in the copy. Describe the optimum variation of graphical drawings resulting in the sharpest hidden image in the copy. Ensure that the original can be distinguished from the copy made by a qualified technician.

Description of the Invention

For encoding hidden video, the background is subdivided into zones of different micro-images. Copying will inevitably result in changes to the elements of the micro drawing. It is necessary to ensure that these changes are different, resulting in a hidden image.

Simple shapes like circles change less in shape than complex shapes like stars or thin lines. It follows that one of the zones must be filled with round dots. The raster with dot liner should be such that the raster is reproduced, at least in part, by simple copying techniques such as fax. On the contrary, the second zone must be filled with thin and intersecting lines. The thin line is the figure that has the highest perimeter to area ratio. Thin line intersections determine the concentration of paint in the resulting corners.

Another important effect is the moiré. The use of a zero raster angle is not recommended due to the possible occurrence of a moiré, but the likelihood of such a moiré in the copy is even greater, so the use of a zero raster angle is justified. Various copiers also clarify other angles that highlight the moiré. If the print vectors are rotated in a 180 degree arc, this defect will appear in individual fragments of such an arc.

For maximum protection, the thickness of thin lines must be within the technical capabilities of the printing equipment. In offset-printed documents, the thickness of the thin lines is usually 0.05 mm.

The drawing must have an irregular structure to provide a higher degree of protection against counterfeiting. An irregular structure is formed using the random variable generator function to create a drawing. For example, if a drawing element of 0.16 mm size can be rotated randomly in four different directions, then the probability of randomly overlapping 50mm x 50mm fragments will be I / 100'000. Magnifying glass or contact microscope should be used for expert level authentication. It is necessary to compare the sample drawing and the original benchmark in several selected locations. To increase the security level, the document is printed in two colors. For example, a unique drawing with a hidden image is printed in blue and the text above is printed in black. The counterfeiter cannot distinguish the pattern beneath the black letters, and if the pattern is not under the letters at a later printing time, the letters will have a glow. This ensures professional-level copy protection in addition to the hidden video effect.

Description of illustration Fig. is an enlarged fragment of a microprint that causes the hidden image to appear during copying. There are areas filled with round dots and areas filled with folded and merging thin lines rotated randomly.

Claims (1)

Definition 1. A technical protection method for protecting printed matter from copying, comprising forming a graphic design of elements of various shapes, characterized in that one part of the design is filled with round dots and the other with thinly curved and tangent lines that are rotated randomly.