Method and apparatus for orienting magnetic flakes
View Patent ↗Apparatus and related methods align magnetic flakes in a carrier, such as an ink vehicle or a paint vehicle to create optically variable images in a high-speed, linear printing operation. Images can provide security features on high-value documents, such as bank notes. Magnetic flakes in the ink are aligned using magnets in a linear printing operation. Selected orientation of the magnetic pigment flakes can achieve a variety of illusive optical effects that are useful for decorative or security applications.
1. An image printed on a substrate, the image comprising:
a first image portion having magnetic flakes and a second image portion having magnetic flakes, adjacent to the first image portion, having a distinct border therebetween;
wherein the magnetic flakes in the first image portion are tilted in a first direction, parallel to each other, and the magnetic flakes in the second image portion are tilted in a second direction, parallel to each other, the first and second directions forming a “V”-shape, so as to provide the first image portion appearing lighter than the second image portion when viewed from a first viewing direction and the first image portion appearing darker than the second image portion when viewed from a second viewing direction.
2. The image according to claim 1 wherein the magnetic flakes are colored.
3. The image according to claim 1 wherein the magnetic flakes comprise an optical interference structure.
4. The image according to claim 1 wherein the magnetic flakes are dispersed in a tinted carrier.
5. The image according to claim 1 wherein at least some of the magnetic flakes have one or more diffractive structures therein, or thereon.
6. A document comprising:
an illusive image providing a security feature, the illusive image including a first image portion having magnetic flakes and a second image portion having magnetic flakes, adjacent to the first image portion, having a visually distinct border therebetween,
wherein the magnetic flakes in the first image portion are tilted in a first direction, parallel to each other, and the magnetic flakes in the second image portion are tilted in a second direction, parallel to each other, the first and second directions forming a “V”-shape, so as to provide the first image portion appearing lighter than the second image portion when viewed from a first viewing direction and the first image portion appearing darker than the second image portion when viewed from a second viewing direction.
7. The document according to claim 6 wherein the document is a bank note.
8. A document as defined in claim 6 wherein at least some of the magnetic flakes are diffractive.
9. A document as defined in claim 8 , wherein the diffractive flakes have diffractive structures therein or thereon.
10. A document as defined in claim 6 wherein the first image portion is directly adjacent the second image portion.
11. A document as defined in claim 10 wherein the first image portion and the second image portion form a “flip-flop” so that when the image is tilted back and forth along a line through the first and second image or the direction of a light source incident upon the image is changed from a non-normal direction incident upon the first image portion to a non-normal direction incident upon the second image portion the first image portion and the second image portion appear to have a switching optical effect.
12. A document as defined in claim 10 , wherein the first image portion and the second image portion together form a character.