DYNAMIC APPEARANCE-CHANGING OPTICAL DEVICES (DACOD) PRINTED IN A SHAPED MAGNETIC FIELD INCLUDING PRINTABLE FRESNEL STRUCTURES

• US 20060198998A1
• Filed: 04/04/2006
• Published: 09/07/2006
• Est. Priority Date: 07/15/2002
• Status: Active Grant

• Current Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Original Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Inventors: Raksha, Vladimir P., Phillips, Roger W., Coombs, Paul G., Markantes, Charles T., Argoitia, Alberto
• Granted Patent: US 8,343,615 B2
• Time in Patent Office: Days
• US Class Current: 428/323
• CPC Class Codes: B05D 3/207 post-treatment by magnetic fields
• CPC Class Codes: B41M 3/148 Transitory images, i.e. images only visible from certain viewing angles
• CPC Class Codes: B42D 2033/16 Magnetic or magnetisable material
• CPC Class Codes: B42D 2035/20 Optical effects
• CPC Class Codes: B42D 25/29 Securities; Bank notes
• CPC Class Codes: B42D 25/369 Magnetised or magnetisable materials
• CPC Class Codes: G02B 26/026 based on the rotation of particles under the influence of an external field, e.g. gyricons, twisting ball displays based on orientable dipolar particles G02F1/172; based on electrophoresis G02F1/167
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 5/09 Multifaceted or polygonal mirrors , e.g. polygonal scanning mirrors; Fresnel mirrors
• CPC Class Codes: G09F 3/0376 using a special technique to detect tampering, e.g. by ultrasonic or optical means
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles

Abstract

A printed image is disclosed wherein the image may be in the form of an array of magnetically aligned platelets or flakes that may by uniform in shape and size and wherein the flakes are arranged in a particularly manner to form optically illusive images useful as security devices, or useful in beam steering applications. In one embodiment of this invention printed array is disclosed a plurality of concentric rings of magnetically aligned platelets disposed upon a substrate in the form of a Fresnel structure, preferably a Fresnel reflector. Advantageously, since the magnetic field can be controlled with respect to strength and direction, one can easily design a field that will correct for spherical aberration that would otherwise be present in a typical Fresnel reflector. In other embodiments of the invention optically illusive images of funnels, domes and cones are printed.

Claims

1. A security device comprising an image having a first plurality of at least n magnetically alignable flakes resting upon a substrate in a first pattern so as to define a ring or curve, wherein the flakes are tilted at the same first angle with respect to the substrate, wherein n>

1000.

2. A security device as defined in claim 1 wherein planes extending from surfaces of the flakes intersect with one another.

3. A security device as defined in claim 2, wherein the first plurality of magnetically alignable flakes define a plurality of concentric rings of flakes, and wherein the rings of flakes populate a circular-like region and wherein the flakes defining the rings form an increasing or decreasing angle with respect to the substrate from the outermost ring to the inner most ring.

4. A security device as defined in claim 1 comprising a second plurality of magnetically alignable flakes resting upon the substrate in a corresponding pattern to the first pattern and wherein the flakes are tilted at a same second angle with respect to the substrate, wherein the second angle is different than the first angle and wherein planes extending from along surfaces of the second plurality of flakes intersect with each other.

5. A security device as defined in claim 4, wherein the plurality of magnetically alignable flakes are distributed substantially throughout an entire closed region and oriented in a predetermined pattern therein, wherein at least more than 50% of the flakes are oriented such that lines normal to their reflecting surfaces converge along a line or to a point.

6. A security device as defined in claim 1 comprising n groups of magnetically alignable flakes resting upon the substrate in n patterns and wherein the flakes within each group of the n groups are tilted at a same angle with respect to the substrate and wherein each of the n groups of flakes are tilted at a different angle with respect to the substrate, and wherein the planes of each group of the n groups of flakes intersect with each other.

7. A security device as defined in claim 6 wherein n>

10,000.

13. The security device as defined in claim 3, wherein the image forms a Fresnel structure.

14. The security device as defined in claim 3, wherein the image forms a part of a receiving or reflecting antenna and wherein the flakes are absorbing or reflecting, respectively.

15. The security device as defined in claim 3 wherein the flakes have a surface area between 100 μ

m² to 1 mm² and wherein the flakes are within a range of thickness between 100 nm and 100 μ

m.

16. The security device as defined in claim 3 wherein the magnetically alignable flakes are aligned with a magnetic field that is present entirely throughout a circular region.

17. The security device as defined in claim 3 wherein the flakes blanket an entire circular region.

18. The security device as defined in claim 3 wherein at least some of the flakes having gratings therein or thereon, and wherein the frequency and depth of the grating is sufficiently low so as to not have diffractive effects that can be seen by the naked human eye, and wherein the flakes having gratings are aligned along lines of the respective grating.

19. The security device as defined in claim 3 wherein at least some of the flakes having gratings therein or thereon, and wherein the frequency of the gratings is less than 200 ln/mm and wherein the depth of the grating is less than 100 microns.

20. The security device as defined in claim 3, wherein the image is an image of one of a cone, a sphere, a hemisphere, and a funnel.

21. The security device as defined in claim 3, wherein the image forms a printed array of reflecting elements in the form of a Fresnel structure.

22. The security device as defined in claim 3, wherein the flakes are uniform in shape.

23. The security device as defined in claim 3 wherein a plurality of the flakes are hexagonal in shape.

24. The security device as defined in claim 3 wherein a plurality of the flakes have a diffractive structure therein or thereon.

8. An optically illusive image comprising a substrate having a region of flakes coating a surface thereof, wherein the flakes are distributed throughout substantially the entire region and oriented in a predetermined pattern therein, wherein the flakes are oriented such that lines normal to their reflecting surfaces converge along a line or to a point.

9. A label or security device comprising an optically illusive image having flakes covering and distributed throughout an entire region and oriented in a predetermined pattern, the flakes having reflecting surfaces, wherein the orientation of the flakes forming the predetermined pattern is such that lines normal to the reflecting surfaces of the flakes converge along a line or at a point, wherein the predetermined pattern has an axis of revolution.

10. An optical element comprising a plurality of concentric rings of magnetically aligned platelets disposed upon a substrate in the form of a Fresnel structure.

11. The optical element as defined in claim 10, wherein the Fresnel structure is a Fresnel reflector.

12. An optical element, comprising a plurality of magnetically aligned flakes oriented in a pattern defining a Fresnel concave or convex shaped structure.

25. An optical element as defined in claim 12, wherein the Fresnel structure is absent spherical aberration.