EP0490457B1
Expired / Lapsed
EP
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Support provided with a security element
Assignee: Enschede Joh En Zonen Grafische Inrichting BV
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Filing: 1991-12-11
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Granted: 1996-04-17
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Expires: 2011-12-11
Abstract
Abstract A support is provided with a machine-detectable security element, particularly a copying-security element. The security element comprises a first image perceptible to the human visual system, said first image incorporating a second image that is substantially imperceptible to the human visual system. <IMAGE>
Inventors
- 👤 Sijbrand Spannenburg
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 07:36
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/00838; H04N1/00856; H04N1/00875; B; B42; B42D; B42D25/00; B42D25/20; B42D25/29; H04N1/0084; H04N1/00843; H04N1/00846; H04N1/00859; H04N2201/00; H04N2201/32; H04N2201/3201; H04N2201/3269; H04N2201/327; Y; Y10; Y10S; Y10S283/00; Y10S283/901; Y10S283/902
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
114 words
An image support carrying a first image perceptible to the human visual system, and a machine-detectable security element, particularly a copying-security element, said first image being composed of line segments arranged in a regular raster pattern, characterized in that line segments have different angular orientations in a plane of the support, said first image incorporates a second image that is substantially imperceptible to the human visual system, said second image being formed by the difference in angular orientation of the line segments, said angular orientation of the line segments being a function of a gradation value of the security element, said first and second images being perceptible to the human visual system after copying.
Claim 2
Dependent Claim
56 words
An image support according to claim 1, characterized in that the function of the gradation value is a continuous function of the gradation value of a security element forming an area identical to the area formed by the first image, said first image and said security element being perceptible to the human visual system after copying.
Claim 3
Dependent Claim
93 words
An image support according to claim 2, characterized in that said function is: φ i = (d(x,y) - d min ) (d max - d min ) π + φ 0 wherein φ i is the angle formed by line segment i having coordinates (x,y) within the area of the raster pattern, d (x,y) is the gradation value of the security element at the point (x,y) within the area of the security element, d min is the minimum gradation value, d max is the maximum gradation value, and φ₀ is an initial angle.
Claim 4
Dependent Claim
120 words
Method of producing a regular raster pattern for printing a first image perceptible to the human visual system on an image support, and a machine-detectable security element, particularly a copying-security element, said regular raster pattern consisting of raster picture elements each consisting of a line segment, said method being characterized in that line segments are given different angular orientations in a plane of the support, in that a second image is incorporated into the first image by forming said angular orientations of line segments as a function of a gradation value of the security element, said second image being substantially imperceptible to the human visual system, said first and second images being perceptible to the human visual system after copying.
Claim 5
Dependent Claim
53 words
Method according to claim 4, characterized in that as said function a continuous function of the gradation value of the security element forming an area identical to the area formed by of the raster pattern is chosen, said first image and said security element being perceptible by the human visual system after copying.
Claim 6
Dependent Claim
91 words
Method according to claim 5, characterized in that said function is: φ i = (d(x,y) - d min ) (d max - d min ) π + φ 0 wherein φ i is the angle formed by line segment i having coordinates (x,y) within the area of the raster pattern, d (x,y) is the gradation value of the security element at the point (x,y) within the area of the security element, d min is the minimum gradation value, d max is the maximum gradation value, and φ₀ is an initial angle.
References Cited (Backward Citations)
WO1992006854A2
Cited
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