Support provided with a machine detectable copying security element
First Claim
Patent Images
1. A support provided with a machine-detectable copying security element comprising a first image perceptible to the human visual system and comprising multi-tone portions formed by image elements, said first image incorporating a second image detectable by a copying machine but substantially imperceptible to the human visual system and being formed by a deformation of at least a number of said image elements forming said first image.
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Abstract
A support 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.
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Citations
20 Claims
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1. A support provided with a machine-detectable copying security element comprising a first image perceptible to the human visual system and comprising multi-tone portions formed by image elements, said first image incorporating a second image detectable by a copying machine but substantially imperceptible to the human visual system and being formed by a deformation of at least a number of said image elements forming said first image.
- 2. A support provided with a machine-detectable copying security element comprising a first image, perceptible to the human eye at a normal distance of assessment, composed of image elements, at least a number of the image elements having a deformation in relation to a rounded dot, wherein this deformation is not perceptible to the human visual system at a normal distance of assessment, but is detectable by a copying machine.
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14. A support provided with a machine detectable copying security element comprising a first image perceptible to the human visual system and formed by image elements, said first image incorporating a second image that is substantially imperceptible to the human visual system, hence forming no portion of said perceived first image, said second image being formed by a deformation of at least a number of said image elements, said second image being detectable by a copying machine.
- 15. An image support carrying an image perceptible to the human visual system, said support having an image support axis, said image being composed of line segments arranged in a regular raster pattern, each line segment forming an angle with respect to the image support axis, at least one of the line segments forming a maximum angle, at least another of the line segments forming a minimum angle, the angles formed by the other line segments varying continuously between the minimum and maximum angles, the angular orientations of said line segments being substantially imperceptible to the human visual system, and said image being reproducible by copying.
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18. A method of producing a regular raster pattern for printing an image perceptible to the human visual system on an image support, said regular raster pattern having a raster axis, said regular raster pattern consisting of raster picture elements each consisting of a line segment, the method comprising providing each line segment with an individual angular orientation with respect to the raster axis, at least one of the line segments forming a maximum angle with respect to the raster axis, at least another of the line segments forming a minimum angle with respect to the raster axis, the angles formed by the remaining line segments varying continuously between the minimum and maximum angles, said angular orientations of said line segments being substantially imperceptible to the human visual system.
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19. A method of producing a regular raster pattern for printing an image perceptible to the human visual system on an image support, said regular raster pattern having a raster axis, said regular pattern consisting of raster picture elements each consisting of a line segment, the method comprising providing each line segment with an individual angular orientation with respect to the raster axis, at least one of the line segments forming a maximum angle with respect to the raster axis, at least another of the line segments forming a minimum angle with respect to the raster axis, the angles formed by the remaining line segments varying continuously between the minimum and maximum angles, said continuously varying angles of the line segments within an area of the raster pattern being a continuous function of a gradation value of a security element forming an area identical to said area of the raster pattern, said angular orientations of said line segments being substantially imperceptible to the human visual system, said image and said security element being reproducible by copying.
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20. A method of producing a regular raster pattern for printing an image perceptible to the human visual system on an image support, said regular raster pattern having a raster axis, said regular pattern consisting of raster picture elements each consisting of a line segment, the method comprising providing each line segment with an individual angular orientation with respect to the raster axis, at least one of the line segments forming a maximum angle with respect to the raster axis, at least another of the line segments forming a minimum angle with respect to the raster axis, the angles formed by the remaining line segments varying continuously between the minimum and maximum angles, said continuously varying angles of the line segments within an area of the raster pattern being a continuous function of a gradation value of a security element forming an area identical to said area of the raster pattern, said function being defined by the expression:
- ##EQU4## wherein Φ
i is the angle formed by the 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, dmin is the minimum gradation value, dmax is the maximum gradation value, and Φ
O is an initial angle, said angular orientations of said line segments being substantially imperceptible to the human visual system, said image and said security element being reproducible by copying.
- ##EQU4## wherein Φ
Specification