SENSOR ELEMENT FOR STORING ROTATION OR POSITION INFORMATION AND STORAGE SYSTEM WITH A SENSOR ELEMENT

Description

AREA OF TECHNOLOGY

[0001] The invention relates to a sensor element for storing rotation or position information, for example for an angle or length measuring device according to claim 1, and a storage system with a sensor element.

[0002] Angle measuring devices are used, for example, as rotary encoders to determine the angular position of two machine parts that can rotate relative to each other. Often, so-called multi-turn angle measuring devices are used for this purpose, enabling absolute position determination over many revolutions.

[0003] Furthermore, length measuring devices are known in which a linear displacement of two machine parts that can be moved relative to each other is measured. Particularly in length measuring devices with a comparatively large measuring length, several linear scales or identical scales are often arranged in a row. With such length measuring devices, an absolute position determination should be possible over as much of the measuring length as possible.

[0004] Such measuring devices or measuring instruments for electric drives are frequently used to determine the relative movement or position of corresponding machine parts. In this case, the generated position values ​​are fed to downstream electronics for controlling the drives via a suitable interface arrangement.

[0005] For many applications of position measuring devices, especially angle measuring or length measuring devices, it is important to store at least the number of revolutions or rough positions in a non-volatile manner. STATE OF THE ART

[0006] EP 1 740 909 B1 describes a sensor element for a revolution counter in which domain walls are formed, and the sensor element has a special spiral shape.

[0007] Patent application US 2010 / 0301842 A1 discloses a revolution counter featuring domain wall conductors. These conductors have loops with tapered protrusions pointing inwards. A desired domain configuration can be inscribed by means of an additional current conductor.

[0008] Patent US 4,157,591 discloses a storage device in which information can be stored in domain conductor structures using a rotating magnetic field. SUMMARY OF THE INVENTION

[0009] The invention is based on the objective of creating a sensor element that includes a domain wall conductor and that enables initialization or a reset in an economical design.

[0010] This problem is solved according to the invention by the features of claim 1.

[0011] The invention relates to a sensor element for the active storage of rotation or position information. The sensor element comprises a domain wall conductor arranged on a substrate, the path of which is designed to be free of intersections. The domain wall conductor, or its path, also has a first region with a positive curvature and a second region with a negative curvature. Furthermore, the sensor element comprises an electrically conductive layer applied to the substrate, which is arranged overlapping the domain wall conductor and electrically insulated from it. The electrically conductive layer has four contact points. These are arranged such that applying an electrical voltage to two contact points causes an electric current to flow in a first current direction, so that domain walls can be generated in the domain wall conductor by its magnetic field.The four contact points are arranged such that an electrical voltage can be applied to two pairs of contact points, allowing the electric current to flow either in the first current direction or in a second current direction. According to an advantageously simple arrangement, the first current direction corresponds to the direction of a connecting line between the first and second contact points. The second current direction can correspond to the direction of a connecting line between the third and fourth contact points. According to the invention, the first current direction is oriented orthogonally to the second current direction.

[0012] The electrically conductive layer is electrically insulated and positioned orthogonally to the plane of the substrate relative to the domain wall conductor. The electrically conductive layer thus covers the domain wall conductor completely or only partially, with electrical insulation. In particular, the domain wall conductor can be applied to an insulating layer, with the electrically conductive layer covering the entire surface of the opposite side of the insulating layer.

[0013] The term active storage refers to storage for which the sensor element in question does not require any auxiliary electrical energy.

[0014] Advantageously, the path of the domain wall conductor is designed to be axially symmetrical with respect to an axis. The axis can be inclined at an angle relative to the first current direction, or the current direction can run at an angle to the axis. In particular, the angle between the first current direction and the axis is greater than 10° and less than 60° (10° < β < 60°), and advantageously greater than 15° and less than 50° (15° < β < 50°). Thus, the axis and the first current direction in the electrically conductive position, for example, enclose an angle between 10° and 60°, where the smaller of the two is meant.

[0015] Domain wall conductors, in the context of the present invention, are in particular conductor tracks or nanowires made of a magnetizable material. Information can be stored in the domain wall conductors in the form of oppositely magnetized regions (domains). The domains are separated by so-called domain walls, which can be displaced by magnetic fields, thereby changing the positions of the domains. Readout elements are arranged to determine their position; the domains or domain walls are shifted past these elements. Functionally, domain wall conductors can therefore also be considered a type of shift register.

[0016] Advantageously, the domain wall conductor has a closed, continuous path. Alternatively, the domain wall conductor can also have a continuous path.

[0017] The domain wall conductor forms a continuous curve and exhibits neither a jump nor a peak, kink, or any other point of discontinuity. The term "continuous curve" therefore refers to a domain wall conductor that is uniform and free of abrupt changes in direction. Mathematically speaking, the domain wall conductor is continuous and, in particular, differentiable along its entire length, meaning that a unique tangent can be generated at every point along its path. Specifically, the domain wall conductor exhibits radii of curvature greater than 0.005 mm, preferably greater than 0.02 mm, and ideally greater than 0.03 mm, along its entire path.

[0018] The term "crossing-free course of the domain wall conductor" means in particular that the domain wall conductor does not cross itself in its course, but also is not arranged in different positions crossing over each other.

[0019] Curvature refers to the change in direction along the path of the domain wall conductor on the substrate, which is typically planar. For a straight path, the curvature is zero because the direction of travel does not change. If the curvature is not zero, it can be defined as having a sign relative to the orientation of the normal bundle of the path's curve. The curvature is positive if it curves in the direction of the unit normal vector field and negative if it curves in the opposite direction. For example, the first region with positive curvature can be described as convex, while the second region with negative curvature can be described as concave. Mathematically speaking, the path of the domain wall conductor therefore has at least one inflection point.

[0020] According to an advantageous embodiment, the sensor element further comprises readout elements by which the local magnetization state of the domain wall conductor can be determined (at the respective position of the readout elements). Thus, a magnetization state of the domain wall conductor can be determined by means of the readout elements. The readout elements are arranged in a fixed position relative to the domain wall conductor.

[0021] In a further embodiment of the invention, the domain wall conductor is arranged in a layer between at least one of the selection elements and the substrate. Alternatively or additionally, at least one of the selection elements is arranged in a layer between the substrate and the domain wall conductor.

[0022] It is advantageous for the readout elements to be designed as GMR or TMR sensors.

[0023] The sensor element can have multiple domain wall conductors. In this case, the multiple domain wall conductors have different numbers of first regions or different numbers of second regions. For example, the sensor element can have a first domain wall conductor and a second domain wall conductor, where the first domain wall conductor has a first number of first regions and the second domain wall conductor has a second number of first regions.

[0024] Advantageously, the different numbers—that is, the number of first regions of the first domain wall conductor and the number of first regions of the second domain wall conductor—are coprime. As is well known, coprime means that for the numbers in question (natural numbers), there exists no natural number other than one that divides both numbers.

[0025] According to a further aspect, the invention comprises a storage system comprising a sensor element, a component, and a support magnet. The component includes a magnet arrangement and is designed to be movable in a first direction relative to the domain wall conductor. The support magnet is arranged to be fixed relative to the sensor element, in particular such that the sensor element is located between the magnet arrangement and the support magnet. Alternatively, the support magnet is arranged to be movable relative to the sensor element next to the magnet arrangement on the component with respect to the first direction. Furthermore, the support magnet is configured such that the domain wall conductor can be initialized by the magnetic field of the support magnet in superposition with the induced magnetic field of the electrically conductive layer.

[0026] The component can be designed, for example, as a drum with an angular scale or as a length scale.

[0027] The movement of the magnet arrangement in the first direction relative to the domain wall conductor causes a displacement of magnetic domains or domain walls.

[0028] Advantageously, the supporting magnet is arranged such that a connecting line between its north pole and its south pole is oriented in a second direction, the second direction being oriented such that it has a component orthogonal to the first direction. In particular, the connecting line runs in a plane or surface parallel to the substrate.

[0029] Both the magnets of the magnet arrangement and the support magnet are specifically designed as permanent magnets.

[0030] Advantageously, the sensor element comprises a particularly flat substrate and the domain wall conductor is designed as a conductor track on the substrate.

[0031] In a further embodiment of the invention, the width of the domain wall conductor is less than 1000 nm, in particular less than 500 nm, advantageously less than 300 nm.

[0032] The thickness or layer thickness of the domain wall conductor is advantageously less than 200 nm, in particular less than 150 nm, and in particular less than 60 nm.

[0033] The substrate advantageously has a glass layer and / or a silicon layer. In particular, if the substrate has a silicon layer, the sensor element can be integrated as part of a CMOS chip.

[0034] It is advantageous for the sensor element and the support magnet to be arranged in a common housing.

[0035] Advantageously, the magnetic field generated by the magnet arrangement is asymmetrical with respect to an axis parallel to the first direction. This applies to any imaginary axis parallel to the first direction.

[0036] Advantageously, in a further embodiment of the invention, the magnetic field generated by the magnetic arrangement is symmetrical with respect to an axis that runs parallel to a second direction. The second direction is oriented orthogonally to the first direction.

[0037] The axis that runs parallel to the first direction and the axis that runs parallel to a second direction lie in a plane that is oriented parallel to the substrate.

[0038] In a further embodiment of the storage system, the magnet arrangement is designed as a magnet array, which has magnets whose poles are arranged offset from each other in the first direction.

[0039] The path of the domain wall conductor is advantageously designed to be axially symmetrical. In particular, the relevant axis of symmetry can run parallel to or in the second direction.

[0040] The domain wall conductor has an extent in the first direction, and two magnetic poles have a center-to-center distance, where the extent is smaller than the center-to-center distance. Here, the maximum extent of the domain wall conductor in the first direction is particularly important. The center-to-center distance can be, in particular, the distance between the effective centers of the magnets. For example, in the case of cylindrical bar magnets, the center-to-center distance can be seen as the distance between the longitudinal axes of the cylindrical bar magnets.

[0041] The storage system is designed to have at least two domain walls, although configurations with four or more domain walls can also be used.

[0042] The storage system can be used in conjunction with an angle measuring device, where, in particular, the number of revolutions is stored. Alternatively, the storage system or the sensor element can be used in conjunction with a linear scale. The scale can, in particular, comprise a first scale segment and a second scale segment. The first and second scale segments can be arranged in a line along the first direction, allowing for a comparatively long measuring length. In practice, more than two scale segments can also be arranged in a line. Magnet arrangements are then provided, offset from each other along the first direction. The sensor element makes it possible to store corresponding position information, so that it can be determined which of the scale segments is currently being scanned.

[0043] Advantageous embodiments of the invention can be found in the dependent claims.

[0044] Further details and advantages of the sensor according to the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The show Figure 1a a top view of a sensor element, Figure 1b a side view of a sensor element, Figure 2 a detail view of a domain wall conductor, Figure 3 a magnet of a magnet arrangement, Figure 4 a top view of the magnet arrangement according to a first embodiment, Figure 5 a side view of a component with the magnet arrangement, Figure 6 a top view of the component and the sensor element, Figure 7 a schematic view of the domain wall conductor, a support magnet and the magnet arrangement in a first relative position to each other, Figure 8 a schematic view of the domain wall conductor, the support magnet and the magnet arrangement in a second relative position to each other, Figure 9 a schematic view of the domain wall conductor, the support magnet and the magnet arrangement in a third relative position to each other, Figure 10 a schematic view of the domain wall conductor, the support magnet and the magnet arrangement in a fourth relative position to each other,Figure 11 shows a schematic view of the domain wall conductor, the support magnet, and the magnet arrangement in a fifth relative position to each other. Figure 12 shows a schematic view of the domain wall conductor, the support magnet, and the magnet arrangement in a sixth relative position to each other. Figure 13 shows a schematic view of the domain wall conductor, the support magnet, and the magnet arrangement in a seventh relative position to each other. Figure 14 shows a schematic view of the domain wall conductor, the support magnet, and the magnet arrangement in an eighth relative position to each other. Figure 15 shows a schematic view of the domain wall conductor, the support magnet, and the magnet arrangement in a ninth relative position to each other.Figure 16: A schematic view of the sensor element with a further domain wall conductor and the magnet arrangement according to a second embodiment. Figure 17: A schematic view of the domain wall conductor in a first phase of an initialization or reset process. Figure 18: A schematic view of the domain wall conductor in a second phase of the initialization or reset process. Figure 19: A schematic view of the domain wall conductor in a third phase of the initialization or reset process. Figure 20: A top view of the magnet arrangement according to a third embodiment. Figure 21: A schematic view of the domain wall conductor, the support magnet, and the magnet arrangement according to the third embodiment in a first relative position to each other. Figure 22: A schematic view of the domain wall conductor in a further phase of an initialization or reset process.Figure 23 shows a schematic view of the domain wall conductor after the next phase of an initialization or reset process; Figure 24 shows a side view of a component with the magnet arrangement and a support magnet according to a fourth embodiment. DESCRIPTION OF THE EXECUTION FORMS

[0046] In the Figure 1a Figure 1 shows a sensor element comprising a domain wall conductor 1.1 and a substrate 1.2. In the presented embodiment, the substrate 1.2 has a mechanically load-bearing glass layer and is planar. Alternatively, the substrate 1.2 can have a silicon layer, in which case the sensor element 1 can be configured as part of a CMOS chip. The sensor element 1 has a layered structure that can be simplified and described below (see also the Figure 1bOn the substrate 1.2, an electrically conductive layer 1.7 is applied, which here is designed as a copper layer only a few µm thick. This electrically conductive layer 1.7 has a first contact point 1.71, a second contact point 1.72, a third contact point 1.73 and a fourth contact point 1.74.

[0047] An electrically insulating layer 1.8 is located on the conductive layer 1.7. In the presented embodiment, the conductive layer 1.7 completely covers the electrically insulating layer 1.8 on the side facing away from the domain wall conductor 1.1. The domain wall conductor 1.1, in the form of a conductor track, is applied to the insulating layer 1.8. The electrically conductive layer 1.7 is arranged completely beneath the domain wall conductor 1.1, so that the electrically conductive layer 1.7 overlaps the domain wall conductor 1.1. The term "overlapping" expresses that, with respect to a third direction z ( Figure 1b The electrically conductive layer 1.7 and the domain wall conductor 1.1 are stacked on top of each other, although separated by the thin insulating layer 1.8. The insulating layer 1.8 electrically insulates the domain wall conductor 1.1 from the conductive layer 1.7.

[0048] Alternatively, the layer structure can be inverted, meaning that the domain wall conductor 1.1 is applied to the substrate 1.2 and the insulating layer 1.8 is on the domain wall conductor 1.1, and on that, in turn, the electrically conductive layer 1.7.

[0049] The domain wall conductor 1.1 comprises a soft magnetic material, for example, a Ni-Fe alloy. The domain wall conductor 1.1 includes a first section 1.11, in which it runs in relatively tight loops, and a second section 1.12, in which it runs in an arc with a relatively large radius. The first section 1.11 and the second section 1.12 are directly adjacent to each other, so that the domain wall conductor 1.1 forms a closed loop. The domain wall conductor 1.1 is symmetrical with respect to an axis C that is oriented perpendicular to a first direction x and parallel to a second direction y. The domain wall conductor 1.1 has a width X1 in the first direction x.

[0050] In the Figure 2Figure 1 shows a section of the domain wall conductor 1.1. It clearly shows that the domain wall conductor 1.1 has a first region A with a positive curvature and a second region B with a negative curvature. In other words, following the path of the domain wall conductor 1.1, one would encounter both a section with a rightward curvature and a section with a leftward curvature. In the first section 1.11, a first region A with a positive curvature is followed by a second region B with a negative curvature, and then another first region A, and so on. In the presented embodiment, the domain wall conductor 1.1 has a straight path between the first regions A and the second regions B. In the second section 1.12, the sign of the curvature does not change.In the presented embodiment, the curvature or radius of curvature is kept constant.

[0051] In a layered structure on substrate 1.2, the following are located near the domain wall conductor 1.1 according to the Figure 1 Readout elements 3, which can be, for example, GMR sensors or TMR sensors, with which the magnetization state of the adjacent domain wall conductor 1.1 can be determined.

[0052] When a magnetic field moving relative to the domain wall conductor 1.1 is suitably applied to the domain wall conductor 1.1, domain walls W1, W2 shift within the domain wall conductor 1.1 and along the domain wall conductor 1.1, respectively. A magnet arrangement 1.3 is used to generate a suitable magnetic field ( Figure 4 ) used, which in the presented embodiment is designed as a magnet array consisting of several (permanent) magnets 1.31 to 1.33.

[0053] A first magnet 1.31 of the magnet arrangement 1.3 is arranged such that its magnetization is parallel to the second direction y, or rather, the north pole of the first magnet 1.31 is offset from its south pole with respect to the second direction y. A second magnet 1.32 of the magnet arrangement 1.3 is arranged in the first direction x at a distance of ½·X² from the first magnet 1.31. A third magnet 1.33 is positioned opposite the first magnet 1.31 in the first direction x, offset from it. In the presented embodiment, the second magnet 1.32 and the third magnet 1.33 are identical. Accordingly, the magnets 1.32 and 1.33 are designed as cylindrical bodies, with the magnetic poles arranged along the longest axis of symmetry in the manner of a bar magnet. The second magnet 1.32 and the third magnet 1.33 are illustrated in the following example: Figure 3 The second magnet is shown at 1.32.

[0054] The domain wall conductor 1.1 exhibits according to the Figure 1 In the first direction x, an extent X1 is created. The distance X2 between the centers of the first magnet 1.31 and the second magnet 1.32 is dimensioned such that the extent X1 is smaller than the distance X2, X1 <X2 (bezogen auf den Mittenabstand der ersten und des zweiten Magneten 1.31, 1.32).

[0055] The magnet arrangement 1.3 is typically fixed to a component 2 or to a scale. According to the exemplary embodiment, the component 2 has a substantially annular drum 2.1 (see Figures 5, 6). The magnet arrangement 1.3, consisting of the first, second, and third magnets 1.31, 1.32, 1.33, is mounted on its outer circumference. In the second direction y, i.e., offset axially to it, a fine scale 2.12 is applied circumferentially to the drum 2.1 in the presented exemplary embodiment. Alternatively, the magnet arrangement 1.3 can also be arranged on the inner circumference of a drum or a hollow shaft. In addition to the second magnet 1.32 and the third magnet 1.33, further magnets can be placed to homogenize the overall magnetic field.This measure reduces the susceptibility of the storage system to interference from external magnetic fields and allows for larger distance tolerances between component 2 and sensor element 1.

[0056] According to the Figure 6 The sensor element 1, i.e., the domain wall conductor 1.1 with the substrate 1.2, is located within a housing 1.5 with a radial air gap opposite the drum 2.1, in particular the magnet arrangement 1.3. In the presented embodiment, the housing 1.5 is stationary, while the component 2 with the magnet arrangement 1.3 is rotatably mounted, so that when the component 2 rotates in the first direction x (or opposite direction), the magnet arrangement 1.3 moves relative to the sensor element 1. The scale 2.12 can be decoded, for example, by an optical scanner, which is also housed in the housing 1.5.

[0057] Furthermore, according to the first embodiment, a support magnet 1.6 is located in the housing 1.5 and is arranged immovably relative to the sensor element 1. The sensor element 1 is arranged directly opposite the movable magnet arrangement 1.3, and the support magnet 1.6 is located behind the sensor element 1, so that the sensor element 1 is positioned between the magnet arrangement 1.3 and the support magnet 1.6. The first magnet 1.31 is magnetized such that the line connecting its north pole and its south pole is oriented parallel to the second direction y, or parallel to the axis C. The support magnet 1.6 is arranged such that its magnetization is antiparallel to the magnetization of the first magnet 1.31. Accordingly, the line connecting the north pole and the south pole of the support magnet 1.6 also runs parallel to the second direction y, but the pole orientations are opposite (in the figures, the north pole of the first magnet 1.31 is shown).31 above and the north pole of the support magnet 1.6 below).

[0058] In the Figure 7 The diagram shows the magnet arrangement 1.3 and the domain wall conductor 1.1 with the supporting magnet 1.6 behind it in a first position relative to each other. The magnetic field is represented by numerous arrows. In the first position, the domain walls W1 and W2 are in the positions shown in the diagram. Figure 7 , where (as represented by the symbols) the first domain wall W1 is a so-called head-to-head domain wall and the second domain wall W2 is a so-called tail-to-tail domain wall.

[0059] The magnetic field generated by the magnet arrangement 1.3 is oriented with respect to an axis Ax ( Figures 4 and 7The magnetic field 1.3 generated by the magnetic arrangement is asymmetrical with respect to an axis Ay that runs parallel to a second direction y. The second direction is orthogonal to the first direction.

[0060] If the magnet arrangement 1.3 now aligns itself in the first direction x according to the arrow in the Figure 7 As the domain wall conductor 1.1 is moved relative to the domain wall conductor 1.1 (and thus also relative to the substrate 1.2 and the support magnet 1.6), a quasi-rotating magnetic field acts on the domain wall conductor 1.1. As a result, the positions of the domain walls W1 and W2 shift. This displacement field is generated by moving the magnet arrangement 1.3 past the domain wall conductor 1.1, whereby the magnetic field of the magnet arrangement 1.3 is superimposed on the magnetic field of the support magnet 1.6.

[0061] In the Figure 8The domain wall conductor 1.1 is shown in another position, where the magnetic field is shifted in the first direction x compared to the first position. Accordingly, the domain walls W1 and W2 have changed their positions.

[0062] Similarly, as a result of a further displacement of the magnet arrangement 1.3 relative to the domain wall conductor 1.1 along the first direction x ( Figures 9, 10 , 11 The positions of the domain walls W1 and W2 were further shifted. The positions of the domain walls W1 and W2 according to the Figure 11 This includes, for example, the information that the drum 2.1 or component 2, compared to the arrangement of the Figure 7has been moved so far that the magnet arrangement 1.3 has completely passed the domain wall conductor 1.1, which is the case, for example, after the completion of a first revolution. In particular, the magnetic fields of the first and second magnets 1.32, 1.33 cause the domain walls W1, W2 to be displaced over the second section 1.12, in which the domain wall conductor 1.1 runs in an arc with a relatively large radius.

[0063] If component 2 is moved or rotated further in the same direction, the positions of the domain walls W1, W2 do not change initially because the domain wall conductor 1.1 is always under the influence of the magnetic field of the support magnet 1.6, whereby the support magnet 1.6 is arranged immovably relative to the sensor element 1.

[0064] In the presented embodiment, the drum 2.1 or component 2 is to continue rotating in the same direction (first direction x); accordingly, in the Figures 12 to 15 Depending on the positioning of the magnet arrangement 1.3 relative to the domain wall conductor 1.1 or to the sensor element 1, different positions of the domain walls W1, W2 are shown.

[0065] After each passage of the magnet arrangement 1.3 past the sensor element 1, or after each rotation of the component 2, the domain wall W1 has moved to an adjacent first region A of the domain wall conductor 1.1. Similarly, after each rotation, the domain wall W2 has moved from a second region B to an adjacent second region B of the domain wall conductor 1.1, or it is located in the second section 1.12, where the domain wall conductor 1.1 runs in an arc with a relatively large radius. If the starting point is on the arc with the relatively large radius, the domain wall W2 is moved into an arc in the second region B. In an arrangement according to the Figure 1 This would result in five consecutive passes or revolutions in one direction being countable.

[0066] The magnetization directions within sections of the domain wall conductor 1.1, and thus the approximate positions of the domain walls W1 and W2, can be detected by the readout elements 3. This allows for counting revolutions or storing the revolution information in an angle measuring device, even without auxiliary power. This is important, for example, if a shaft is moved by a weight load during a power failure. Furthermore, the domain walls W1 and W2 are shifted depending on the direction of rotation, so that the sensor element 1 can be reliably used in applications that allow both directions of rotation.

[0067] For the function of the storage system, it is important that a magnetic field acts on the domain wall conductor 1.1 as the magnet arrangement 1.3 passes along the first direction x, the direction of which changes depending on the x-position. In particular, quasi-rotating magnetic field lines or directions are present here. Magnetic field lines on one side of the axis Ay ( Figure 7 The magnetic field lines on the opposite side of axis Ay have an opposite direction of rotation. Specifically, the magnetic field lines covering areas A and those covering areas B have opposite directions of rotation.

[0068] According to a second embodiment according to Figure 16A sensor element 1' can comprise several domain wall conductors 1.1, 1.1' to increase the number of countable rotations, wherein the domain wall conductors 1.1, 1.1' each have, for example, a first domain wall W1, W1' and a second domain wall W2, W2'. In this case, it is advantageous if the several domain wall conductors 1.1, 1.1' have different numbers of first sections 1.11, 1.11', in particular different numbers of first areas A or different numbers of second areas B. When using several domain wall conductors 1.1, 1.1', it is advantageous if the number of first areas A of the respective domain wall conductors 1.1, 1.1' are coprime. The several domain wall conductors 1.1, 1.1' can be arranged offset from each other in the first direction x or nested within each other. Figure 16The domain wall conductors 1.1, 1.1' are designed such that they have four and five first areas A, wherein in the Figure 16 For clarity, domain wall conductors 1.1, 1.1' with comparatively small numbers of first sections A are shown. In practice, it is advisable to use domain wall conductors with more than four first sections A. For example, four domain wall conductors can be used with 7, 9, 11, and 13 first sections A, resulting in 9009 (7 x 9 x 11 x 13) countable revolutions.

[0069] Before commissioning, i.e., during initialization of the storage system or during a reset, a predetermined number of domain walls are to be brought into defined positions on the domain wall conductor 1.1, 1.1'. The initialization or reset process is carried out in a position where the sensor element 1 is outside the influence area of ​​the magnet arrangement 1.3. In a first process step, an electrical voltage or potential difference is applied to the first contact point 1.71 and the second contact point 1.72. For example, a charged capacitor can be connected for this purpose, so that its discharge current then flows through the first contact point 1.71 and the second contact point 1.72. Consequently, current flows in the electrically conductive position 1.7 of the sensor element 1, an electric current in a first current direction ξ, which here corresponds to the direction of a connecting line between the first contact point 1.71 and the second contact point 1.72. As can be seen from the . Figure 1a As can be seen, the axis C is inclined at an angle β relative to the first current direction ξ. In the presented embodiment, the angle β is 25°. Thus, the magnetic field induced by the electric current in the electrically conductive layer 1.7 generates a plurality of domain walls W1, W2 in the domain wall conductor 1.1 ( Figure 17The strength of the induced magnetic field is significantly greater than the required nucleation magnetic field for generating domain walls W1, W2. Even though the sensor element 1 is permanently located within the magnetic field of the support magnet 1.6, the magnetic field induced by the electric current is dominant during current flow due to its high field strength. Accordingly, the current flow, or current intensity, in the electrically conductive layer 1.7 must be chosen to be large. Moreover, only very short time periods are required for this process. It is sufficient for the magnetic field induced by the electric current to be present for less than 1 µs, thus preventing overheating due to the heat capacity of the sensor element 1, particularly the substrate 1.2, in conjunction with transient heat conduction, even if comparatively high currents flow briefly. The seven large arrows in the Figure 17are intended to represent the total magnetic field resulting from a superposition of the magnetic field of the support magnet 1.6 and the magnetic field generated by the electric current in the electrically conductive position 1.7.

[0070] In the next step, the current flow in the electrically conductive layer 1.7 is blocked or interrupted, so that the domain wall conductor 1.1 is oriented according to the arrows in the Figure 18 is only exposed to the magnetic field of the support magnet 1.6. This results in the head-to-head domain walls W1 and the tail-to-tail domain walls W2 migrating towards each other in the straight central areas of the domain wall conductor 1.1 ( Figure 18 ) and eventually annihilate each other ( Figure 19Then the desired defined state is reached, in which the remaining first (head-to-head) domain wall W1 lies in a first region A and the remaining second (tail-to-tail) domain wall W2 lies in a second region B. The initialization or reset of the domain wall conductor 1.1 is now complete. In particular, the support magnet 1.6 is configured such that the domain wall conductor 1.1 can be initialized by the magnetic field of the support magnet 1.6 superimposed on the magnetic field of the electrically conductive layer 1.7.

[0071] In the Figure 20A third embodiment is shown, which is particularly suitable for applications where only a few revolutions or cycles need to be counted. In this case, the magnet arrangement 1.3" can be simplified to include only a first magnet 1.31. However, in this simplified arrangement, the first domain wall W1 cannot be pushed through the second section 1.12 of the domain wall conductor 1.1 using the magnetic field generated by the magnet arrangement 1.3". Thus, in this case, the countable number of revolutions or cycles is limited to the number of first sections 1.11 of the domain wall conductor 1.1. In this embodiment, it is not essential that the domain wall conductor be designed as a closed loop.For example, the area with the large radius of curvature, i.e., the second section of the domain wall conductor, could be omitted, so that the domain wall conductor instead has two ends. To stabilize the magnetization, areas with, for example, antiferromagnetic coupling could then be arranged there.

[0072] To initialize the storage system or to reset the domain wall conductor 1.1 for only a relatively small number of revolutions or passes, the same steps are performed as in the first embodiment. Accordingly, the domain wall conductor 1.1 is in the defined state in which one domain wall W1 is located in a first area A in a first section 1.11 and the second domain wall W2 is located in the second section 1.12, according to the Figure 19. For a sensor element 1, with which only a few revolutions or passes need to be counted, it is advantageous that the first domain wall W1 is located as close as possible to the first area A or first section 1.11 in the middle.

[0073] The following process step is also carried out if the sensor element 1 is outside the influence area of ​​the magnet arrangement 1.3, but within the influence area of ​​the support magnet 1.6. This ensures that the first domain wall W1 moves from the position according to the Figure 19As the sensor element is shifted, an electrical voltage or potential difference is applied at the third contact point 1.73 and the fourth contact point 1.74. This results in an electric current flowing in a second current direction ψ in the electrically conductive layer 1.7 of the sensor element 1. Compared to the previously generated current between the first and second contact points 1.71, 1.72, the now applied current is lower. However, the current flow is now maintained for a longer period (a few µs) than before. Afterwards, the domain walls W1, W2 move into positions according to the Figure 22 to lie. The seven large arrows in the Figure 22 are intended to represent the total magnetic field resulting from a superposition of the magnetic field of the support magnet 1.6 and the magnetic field generated by the electric current in the electrically conductive position 1.7.

[0074] The current flow is then interrupted, so that the domain wall conductor 1.1 is only exposed to the magnetic field of the support magnet 1.6. Under these conditions, the domain walls W1, W2 move into positions according to the Figure 23 .

[0075] These last two process steps can now be repeated until the first domain wall W1 lies in the central first area A and the second domain wall W2 lies in the center of the second section 1.12. In this state, which is not explicitly shown in the figures, the domain walls W1 and W2 then lie on the axis C and the maximum number of revolutions or passes in both directions of movement can now be counted.

[0076] In the embodiments presented so far, the storage system is designed such that the support magnet 1.6 is arranged immovably relative to the sensor element 1, wherein the support magnet 1.6 is arranged such that the sensor element 1 is located between the magnet arrangement 1.3, 1.3" and the support magnet 1.6.

[0077] According to a fourth embodiment, see Figure 24Alternatively, a support magnet 2.11 can be arranged on a component 2‴, the component 2‴ being otherwise designed similarly to the first three embodiments. However, the magnet arrangement 1.3‴ here comprises a magnet array of several (permanent) magnets. Furthermore, the drum 2.1‴ has the support magnet 2.11 in the region of its outer circumference. This can, for example, consist of a layer of magnetizable material. The magnetization is carried out such that the north and south poles are axially offset from each other. In the second direction y, i.e., axially offset from the support magnet 2.11, a fine scale 2.12 is also applied circumferentially to the drum 2.1‴.

Claims

1. Sensor element (1; 1') for storing rotation or position information, wherein the sensor element (1; 1') - comprises a domain wall conductor (1.1; 1.1') which is arranged on a substrate (1.2), wherein the course of the domain wall conductor (1.1; 1.1') is without crossings and the domain wall conductor (1.1; 1.1') has a first region (A) with a positive curvature and a second region (B) with a negative curvature, - comprises an electrically conductive layer (1.7) which is applied to the substrate (1.2) and is arranged in an overlapping manner relative to the domain wall conductor (1.1; 1.1') and so as to be electrically insulated with respect to the latter, wherein the electrically conductive layer (1.7) has four contact points (1.71, 1.72, 1.73, 1.74) which are arranged such that two pairs of contact points (1.71, 1.72, 1.73, 1.74) can have a voltage applied to them, with the result that an electric current flows either in a first current direction (ξ) or in a second current direction (Ψ), the first current direction (ξ) being oriented orthogonally with respect to the second current direction (Ψ), with the result that the magnetic field induced by the current can generate domain walls (W1, W2, W1', W2') in the domain wall conductor (1.1; 1.1').

2. Sensor element (1; 1') according to one of the preceding claims, wherein the course of the domain wall conductor is axially symmetrical with respect to an axis (C).

3. Sensor element (1; 1') according to Claim 2, wherein the axis (C) is aligned so as to be inclined by an angle (β) relative to the first current direction (ξ).

4. Sensor element (1; 1') according to Claim 3, wherein the angle (β) is greater than 10° and less than 60°.

5. Sensor element (1; 1') according to one of the preceding claims, wherein the course of the domain wall conductor (1.1; 1.1') is closed circumferentially.

6. Sensor element (1; 1') according to one of the preceding claims, wherein the course of the domain wall conductor (1.1; 1.1') is continuous.

7. Sensor element (1; 1') according to one of the preceding claims, wherein the sensor element (1; 1') also has read-out elements (3) which can be used to determine the local magnetization state of the domain wall conductor (1.1; 1.1').

8. Sensor element (1; 1') according to Claim 7, wherein the read-out elements (3) are in the form of GMR or TMR sensors.

9. Sensor element (1') according to one of the preceding claims, wherein the sensor element (1') has a plurality of domain wall conductors (1.1; 1.1') having different numbers of first regions (A) or different numbers of second regions (B).

10. Sensor element (1') according to Claim 9, wherein the different numbers of first regions (A) are coprime.

11. Storage system comprising a sensor element (1; 1') according to Claim 1, a component (2) and a supporting magnet (1.6, 2.11), wherein - the component (2) comprises a magnet arrangement (1.3; 1.3"; 1.3‴) which can be moved in a first direction (x) relative to the domain wall conductor (1.1; 1.1'), - the supporting magnet (1.6, 2.11) - is arranged immovably relative to the sensor element (1; 1') or - is arranged beside the magnet arrangement (3) on the component (2) based on the first direction (x), wherein the supporting magnet (1.6, 2.11) is configured such that the domain wall conductor (1.1; 1.1') can be initialized in a manner superimposed with the magnetic field of the electrically conductive layer (1.7) by the magnetic field of the supporting magnet (1.6, 2.11).

12. Storage system according to Claim 11, wherein the sensor element (1; 1') is arranged between the magnet arrangement (1.3; 1.3'') and the supporting magnet (1.6).

13. Storage system according to Claim 11 or 12, wherein the supporting magnet (1.6, 2.11) is arranged such that a connecting line between its north pole and its south pole is oriented in a second direction (y), wherein the latter has a component orthogonal to the first direction (x).