Support provided with a machine detectable copying security element

• US 5,374,976 A
• Filed: 08/12/1993
• Issued: 12/20/1994
• Est. Priority Date: 12/13/1990
• Status: Expired due to Term

• Current Assignee: JOH Enschede EN Zonen Grafische Inrichting BV
• Original Assignee: JOH Enschede EN Zonen Grafische Inrichting BV
• Inventors: Spannenburg, Sijbrand
• Primary Examiner(s): Grimley, A. T.
• Assistant Examiner(s): Brase, Sandra L.
• Application Number:
  US08/105,783
• Time in Patent Office: 495 Days
• Field of Search: 355/200, 355/201, 380/54, 380/55, 356/71, 283/72, 283/73, 283/74, 283/94, 283/901, 283/902
• US Class Current: 399/366
• CPC Class Codes: B42D 25/29 Securities; Bank notes
• CPC Class Codes: H04N 1/00846 based on detection of a dedicated indication, e.g. marks or the like
• CPC Class Codes: H04N 1/00859 Issuing an alarm or the like
• CPC Class Codes: H04N 1/00875 Inhibiting reproduction, e.g. by disabling reading or reproduction apparatus
• CPC Class Codes: H04N 2201/327 which are undetectable to the naked eye, e.g. embedded codes
• CPC Class Codes: Y10S 283/901 Concealed data
• CPC Class Codes: Y10S 283/902 Anti-photocopy

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.

Claims

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.

3. A support according to claim 2, wherein the image elements are divided according to a raster pattern.

4. A support according to claim 3, wherein each deformed image element has an angular orientation in a plane of the support.

5. A support according to claim 4, wherein the angular orientation corresponds to a degree of deformation.

6. A support according to claim 2, wherein the deformed image elements consist of line segments.

7. A support according to claim 2, wherein the deformed image elements define a latent image reproducible by a copying machine as a visible addition to the first image.

8. A support according to claim 7, wherein said latent image is superposed on said first image.

9. A support according to claim 8, wherein the degree of deformation of each of the deformed image elements is a function of the gradation value of a corresponding image element of the first image.

10. A support according to claim 9 wherein the function is a binary function.

11. A support according to claim 8, wherein the raster pattern is essentially regular, and the first image is defined by variations in the surface area of individual image elements of the first image.

12. A support according to claim 7, wherein the latent image comprises a bar code.

13. A support according to claim 2, wherein the density of the deformed image elements is beyond the discerning capacity of the human visual system at a predetermined distance of assessment, so that the latent image is perceived by humans as a single tone image.

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.

16. An image support according to claim 15, wherein the continuous variation of the angles of the line segments within an area of the image is a continuous function of the gradation value of a security element forming an area identical to said area of the image, said image and said security element being reproducible by copying.

17. An image support according to claim 16, wherein said function is:

##EQU3## wherein is Φ

i 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 minimum gradation value, and Φ

_O is an initial angle.

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.

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.

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, d_min is the minimum gradation value, d_max 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.