Copy protected security print

Details Copy protected security print Copy protected security print

1999-02-19

2001-04-03

Gerrity, Stephen F. (Department: 3721)

Printed matter

Having revealable concealed information, fraud preventer or...

C283S091000, C283S902000, C380S054000

Reexamination Certificate

active

06209922

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a copy-protected security print having a substantially regular background pattern of lines, dots, screen structures or the like.
2. Description of the Prior Art
It is well known to print documents to be protected from forgery with fine patterns constituting a background for other printed information. This background consists for example of families of lines, guilloches, dot patterns, screen structures and the like. Information, for example texts, logos or numerals, is then printed on this more or less regular background pattern.
Such a security print can be monochrome or colored. A colored security print is preferable to a black-and-white print because it is more difficult to copy. However, highly developed color copiers exist today which are capable of making remarkably good copies even of colored security prints. There are numerous measures for preventing or complicating the forgery of printed documents.
SUMMARY OF THE INVENTION
The problem of the present invention is to provide a security print, and a method for producing such a security print, which cannot be copied by a commercial photocopier without the copy being immediately recognizable.
This problem is solved according to the invention by a copy-protected security print wherein at least one object, for example letters, numerals or the like, is worked into a substantially regular background pattern of lines, dots, screen structures or the like by the components of the background pattern being split at the places occupied by the object, i.e. a line being split into a plurality of partial lines or a solid circle into a ring.
The background formed for example by a plurality of parallel fine lines is mostly perceived only as “gray” at a superficial glance. The individual lines of the background pattern are recognizable as such only upon closer inspection. The same holds for other background patterns, for example a pattern of dots, rectangles, rhombuses or a combination of such background pattern components.
According to the invention these background pattern components are “split” at the places where the “object” is worked in. The term “object” here means any sign or combination of signs, for example individual letters, texts, numerals, logos and the like.
The term “split” means that a continuous printed area, for example a line, is divided up in such a way that the continuous area becomes at least two partial areas, i.e. a continuous line is replaced by two, three or more partial lines. The total width of a group of two or more partial lines is not essentially greater than the continuous line replaced by the partial lines.
The objects worked into the background pattern according to an aspect of the invention are already practically imperceptible with the naked eye at a feature size, for example line width, of less than 150 microns, preferably less than 100 microns. When such a print is copied with a commercial copying machine one can clearly see the thin lines, dots and the like of the background pattern on the copy, but the copy is deficient at the places where the background pattern components are split, i.e. where the object is. Depending on the quality and mode of operation of the copying machine, the object appears much lighter than the rest of the background pattern and at some places the partial lines, partial dots and the like have not been copied at all. That is to say, at these places the object appears completely white, considering for example a black-and-white security print and its copy. In practice one will naturally work such “objects” into the background pattern so that the viewer immediately detects the copy and does not assume the “object” belongs to the original print. For example it is useful to work the word “Copy” or “Forgery” or the like into the background pattern as an “object”. This word will then be immediately recognizable on the copy.
With background patterns consisting of lines, families of lines, groups of lines and the like, or containing such lines, it has proven expedient and sufficient for copy protection to split the individual lines into two partial lines at the places occupied by the object, the width of each partial line preferably corresponding to about half the line width of the original line. If there are two partial lines per line, the width of each partial line is preferably about 40 to 45% of the original line width, and the distance between the paired partial lines is between one third and two thirds of the original line width.
Rather than lines, the background pattern can have dots, that is to say solid circles, alone or in combination with lines, rectangles and other background pattern components. Dots, that is to say solid circles, in the background pattern are split in such a way that the solid circle is replaced by a ring, the area of the ring corresponding to about 50 to 150% of the area of the circle, preferably between 85 and 115%. The thickness of the ring, that is to say the difference between outside radius and inside radius of the ring, corresponds to about half the diameter of the solid circle.
These standard values can also be transferred to other types of background patterns, for example squares. A solid square can be replaced by an angular ring or frame, its line width being selected so that the area of the frame corresponds approximately to that of the solid square. Other possible patterns are rhombuses, ellipses and the like. These patterns can also be combined in almost any desired way.
It has turned out that the exposure of the “object” hardly recognizable with the naked eye by copying the security print depends on the type of copier as well as the orientation of the background pattern with respect to the scanning direction of the security print on the copier. If one experiments with an inventive security print and a commercial copying machine, rotating the security print somewhat on the document glass plate for each copying process, one sees that the “object” does not appear with equal clarity at each copying process.
To optimize the copy protection for the inventive security print, in particular in conjunction with a background pattern in linear form, one preferably varies the orientation of the background pattern continuously or in steps between 0° and 360°. With such a security print some objects or partial areas of an object might appear less clearly and others more clearly. In any case the copy will be immediately recognized as such.
The invention relates furthermore to a method for producing a security print comprising the following steps:
a) supplying print information for the background pattern;
b) supplying positional information for the object to be worked in;
c) supplying modified print information which is capable of replacing the print information for the background pattern in certain places, and replaces the continuous background pattern components by split components; and
d) combining the information according to a), b) and c) in such a way that the print information for the background pattern is replaced by the modified print information at the places where the object is located.
With this method one can produce a composition pattern for an inventive security print using a laser engraving machine for example. The composition pattern can also be prepared by producing a film with the help of an image setter and then transferring the film information. The original information about the background pattern for the entire surface of a security print is stored in a memory. In a further memory the print information about the object is stored, for example the word “FORGERY” to be worked in at a certain place or a plurality of places in the security print. The memory contents are then superimposed in such a way that the print information for the background pattern is replaced at the places of the object by modified print information according to which continuous lines are replaced by paired parallel partial lines for example. After the object has thus been worked into th

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