Marking device, method and apparatus for the production thereof and a method for reading a marking device of this type
View Patent ↗A marking device for the identification of an object includes laterally offset regions formed directly on the object with different magnetic characteristics. The different regions can have histeresis loops shifted differently to one another.
1. A marking device for the identification of an object and formed on the object with laterally offset regions with different magnetic characteristics, wherein the laterally offset regions being adjacent magnetic regions which are so magnetically biased or manufacture that hysteresis loops thereof are shifted differently to each other on a field strength axis (H) relative to a symmetrical pattern on a magnetization axis (M).
2. The marking device according to claim 1 wherein regions with magnetic bias are spaced apart.
3. The marking device as defined in claim 2 wherein between regions with magnetic bias regions are disposed that are not magnetically biased.
4. The marking device according to claim 1 wherein regions with different magnetic bias border one another.
5. The marking device according to claim 1 wherein regions with magnetic bias comprise a layer system having at least one antiferromagnetic layer and at least one ferromagnetic or ferromagnetic or soft magnetic second layer.
6. The marking device according to claim 5 wherein the ferromagnetic or ferromagnetic layer also extends over regions not magnetic biased.
7. The marking device according to claim 5 wherein the antiferromagnetic layer is so assembled from super-imposed ferromagnetic or ferromagnetic and/or nonmagnetic partial layers that they couple in a nonparallel or antiparallel manner.
8. The marking device according to claim 5 wherein regions of the antiferromagnetic layer are built up so that they couple with the ferromagnetic or ferromagnetic layer in at least two different directions.
9. The marking device according to claim 5 wherein the layer system comprising the antiferromagnet layer and the ferromagnetic or ferromagnetic layer is covered with a protective layer.
10. The marking device according to claim 5 wherein the layer system comprising the antiferromagnetic layer and/or the ferromagnetic or ferromagnetic layer is disposed on a smooth or structured carrier consisting of nonmagnetic material.
11. The marking device according to claim 5 wherein the degree of bias is adjustable by disposition of an additional layer at least partly covering said layer system.
12. A method of reading a marking device according to claim 1 with the aid of a magnetic field sensor wherein the marking device is subject to at least two reading processes, wherein one reading process is carried out in a zero field and another reading process is carried out in an external magnetic field or wherein the reading processes are carried out in different external magnetic fields.
13. A marking device for the identification of an object and formed on the object, said marking device having laterally offset regions with different magnetic characteristics, the laterally offset regions being magnetic regions which are so magnetically biased or manufactured that hysteresis loops thereof are shifted differently to each other on a field strength axis (H).