Magnetic system for revolution counting with improved stability against interfering magnetic fields.

Abstract

The present invention relates to a magnetic system for revolution counting with improved stability against interfering magnetic fields. To achieve this, it is necessary to provide a system of this kind that can be used in a significantly higher magnetic field range (B field range) than is normally used in the prior art, with a magnetic window width ΔB as large as possible, i.e., the difference between the lower and upper B limits permitted in use. The system uses an angle sensor for detecting the magnetic field direction of a permanent magnet that captures both the angle sensor and the revolution counter (102), the revolution counter being formed by a GMR or TMR revolution counter of known construction, with both sensors arranged adjacent to each other in a common housing and / or on a common wiring board, and a magnetic damping structure (200) that automatically adjusts the magnetic effect is assigned to the revolution counter (102), which is characterized in that, other than being made of a homogeneous soft magnetic material, the magnetic damping structure has no or only a very small magnetic field of its own when the external magnetic field is zero.

Description

[Background technology]

[0001] Magnetic sensors can detect properties of a magnetic field, for example the magnetic field direction. An example of this is an angle sensor. Other types of magnetic sensors can determine how often a magnetic field has rotated. This type of revolution counter can be formed, for example, by a GMR or TMR revolution counter, which are well known in the prior art. Such sensors usually have a memory function in addition to the sensor function, i.e. they store, for example, how often a permanent magnet has rotated. According to the prior art, the detection of the number of revolutions is usually performed in combination with an angle sensor, which detects the exact direction of the magnetic field. A measuring system for measuring angles in the range of, for example, 0° to 3,600°, consists of an angle sensor for detecting angles between 0° and 180° using an AMR (anisotropic magnetoresistance angle sensor) or an angle sensor for detecting angles between 0° and 360° (using a GMR or TMR angle sensor or a Hall sensor or other angle sensor) and a revolution counter, which makes it possible to detect the number of revolutions (0 to 10 in the above example). Both sensors, i.e. the angle sensor and the revolution counter, are formed as separately manufactured components and are usually arranged next to each other on a wiring board. In addition, as mentioned above, components including evaluation electronics can be arranged on the wiring board, which can evaluate the signals of both sensors, provide a supply voltage and also perform error monitoring, as described for example in European patent application EP 3 387 387 B1. A rotating permanent magnet can be mounted above the angle sensor and the revolution counter, the lateral extent of which is determined such that the stray magnetic field below the permanent magnet sufficiently encompasses both sensors. But also linear arrangements of magnets, which can for example act as a magnetic ruler, generate a rotating magnetic field when the revolution counter moves along it, which can be used to realize distance measurements with the revolution counter.

[0002] The actual arrangement of both components (angle sensor and revolution counter) that are simultaneously exposed to the magnetic field of the permanent magnet is influenced by the properties of both components. In this case, both components can be arranged next to each other on a wiring board, for example. In this geometric arrangement, both components are subjected to the same magnetic flux B, which is generated by the permanent magnet in the plane of the components. As will be explained below, an arrangement is advantageous in which the magnetic flux B at the position of the revolution counter is smaller than the magnetic flux B at the position of the angle sensor. This can be achieved, for example, by arranging both components on opposite sides of a wiring board that is several millimeters thick. This results in an increased distance between the permanent magnet and one of the components by the thickness of the wiring board. If the revolution counter is arranged below the wiring board, the magnetic flux B at the position of the revolution counter will be smaller than the magnetic flux B at the position of the angle sensor, which is exposed to the magnetic field B of the permanent magnet at a closer position due to the increased distance. Another possible arrangement in which the magnetic field B at the position of the revolution counter is smaller than at the position of the angle sensor could be realized by a magnetic shielding layer arranged above the revolution counter. In this case, both sensors could be arranged on the same side of the wiring board. However, in that case the angle sensor and the revolution counter would need to have a larger spacing, since otherwise the shielding layer would undesirably reduce the B-field also at the angle sensor location.

[0003] A magnetic angle sensor achieves its best accuracy when there is a high value (≧100 mT) of the magnetic flux B formed by the permanent magnet at the sensor location. In contrast, a revolution counter can provide error-free detection of the number of revolutions only in a magnetic window that can reach, for example, 15 mT to 30 mT. In order to be able to detect the angle with the angle sensor, for example with an accuracy of better than 0.05°, an encoder magnetic field of at least 100 mT is required. In contrast, for a revolution counter, the encoder magnetic field only needs to be 23% of this optimal value for the angle sensor, i.e. 23 mT, in order to be ideally located in the middle of the B magnetic field range in which the revolution counter operates error-free.

[0004] Due to the different requirements for the magnetic fields acting on both necessary components, the above-mentioned arrangement has the following disadvantage: by arranging both components geometrically adjacent on a wiring board without a shielding layer, a highly accurate detection of the angle is not possible, since the rotation counter usually determines the B-field at the position of the angle sensor to be 23 mT, otherwise the rotation counter would not be able to operate within its defined magnetic window.

[0005] By arranging them on opposite sides of a thick wiring board, both sensors can be operated in their ideal B-field range. However, the thickness of the wiring board must be precisely adjusted to the encoder magnet and must be changed, for example, when using permanent magnets with different geometric conditions (e.g. for compact measurement systems). If such specifications dictate a small size, it is not possible to integrate both sensors in one chip housing.

[0006] The use of a uniform magnetic shielding layer of soft magnetic material above the rotation counter would allow both sensors to be located on the same side of the wiring board, each operating within its optimum B-field range, but integration in a common small chip housing would be impossible due to the need to provide a spacing between the angle sensor and the magnetic shield located above the rotation counter, since such a shield would have to extend laterally by about 60% and, in addition, be spaced from the angle sensor by at least 50% of its lateral extent in order for the effect of the magnetic shield to be substantially limited to the rotation counter and to have little effect on the B-field at the angle sensor.

[0007] In particular, both arrangements without a shielding layer have in common the fact that the influence of external magnetic interference fields acting on the sensor system must be sufficiently reduced by appropriate design measures. Such magnetic interference fields can arise, for example, when high currents are flowing in the vicinity of the sensor system. Another possibility for magnetic interference fields is the use of objects with magnets attached, such as lighting lamps, in the vicinity of the sensor system.

[0008] For all applications, the design of the sensor system must therefore ensure by design measures that the B magnetic field acting on the revolution counter during operation of the sensor system always lies within the specifically specified range of the magnetic window.

[0009] This is illustrated by the example that, under real conditions, the B field of the encoder magnet acts on the revolution counter in the range of 20-25 mT. This range is limited, for example, by the temperature dependence of the magnetization of the encoder magnet and by possible undesired mechanical movements of the permanent magnet during operation, which slightly change the distance between the magnet and the plane on which the revolution counter lies. This means that, with a maximum permissible B field of 30 mT, the structure of the entire system must be designed in such a way that the interfering magnetic fields acting on the entire system are always below 5 mT at the location of the revolution sensor. If this cannot be guaranteed under the conditions of use of the sensor, additional shielding measures must be implemented to achieve this. This generally requires high design and material costs, which entails considerable additional costs.

[0010] The use of a soft magnetic shield at the rotation counter to align the B field with its magnetic window at the rotation counter improves the stability against interfering magnetic fields. For this, a magnetic shield designed, for example, as a soft magnetic disk would have to have a vertical spacing corresponding to approximately 30% of the lateral extent of the sensor. The shield itself would have to have a lateral extent of at least 4 mm and a thickness of 0.5 mm to guarantee the required B field in the area of ​​the rotation counter, assuming a lateral extent of 2 mm. Since the angle sensor must not be covered by the shield to achieve its high measurement accuracy, a minimum spacing of approximately 6 mm is required from the rotation counter, which makes it impossible to arrange both sensors laterally close together or to integrate the angle sensor, the rotation counter and the evaluation electronics on one chip in a common housing of the usual design. At the same time, the permanent magnet must be designed with a lateral expansion in order to bring both sensors into the homogeneous range of the B field. However, a large permanent magnet significantly increases the cost of the entire sensor system. If the angle sensor and the rotation sensor can be placed close to each other, a small permanent magnet can be used, thereby reducing costs. Furthermore, if at least the angle sensor and the rotation counter can be integrated into one housing, the overall price will be lower than if the sensors were in separate housings. Furthermore, the assembly cost will be reduced.

[0011] A rotary counter as described in German patent application DE102008063226A1 contains a magnetic conductor in which the domain walls move. This can be part of a GMR (Giant Magnetoresistance) or TMR (Tunnel Magnetoresistance) stack and can be manufactured in the form of a spiral. Such a spiral magnetic window can be adjusted, for example, by the width of the soft magnetic structures in the stack. A narrower width leads to higher lower and upper limits for the magnetic window. For a rotary counter operating at 100 mT, it would be necessary to reduce the structure width by a factor of four from the previously used structure width of about 350 nm. However, it is difficult to manufacture structures with structure widths of 100 nm or less instead of the hitherto common 350 nm. When using lithography for the structuring, roughness of the magnetic conductor is unavoidable, with a high risk of a significant deterioration in the component yield. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] European Patent Application No. EP3387387B1 [Patent Document 2] German patent application DE102008063226A1 [Patent Document 3] European Patent Application No. EP3066421B1 Summary of the Invention [Problem to be solved by the invention]

[0013] The object of the present invention is to provide a magnetic system for revolution counting which can be used in a significantly higher magnetic field range (B field range) than is normally used according to the prior art, and which has improved stability against interfering magnetic fields. Furthermore, the width ΔB of the magnetic window, i.e. the difference between the lower and upper limits of the B value permitted for use, is as large as possible. [Means for solving the problem]

[0014] This problem is solved by the features stated in the characterizing part of claim 1. The essence of the invention is that the rotary counter is assigned a magnetic damping structure which automatically adjusts its magnetic effect, which, apart from being a structure made of homogeneous soft magnetic material, has no or only a very slight magnetic field of its own in the case of zero external magnetic field. Advantageous embodiments are the subject of the dependent claims.

[0015] The following embodiment examples are used to explain the present invention in detail. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 shows a typical arrangement of an angle sensor and revolution counter according to the prior art. [Diagram 2] FIG. 2 shows a basic design according to the present invention. [Diagram 3] FIG. 3 is a diagram showing an example in which an angle sensor, a rotation counter, and, if necessary, an evaluation electronic circuit are integrated on a single chip. [Figure 4] FIG. 4 shows a first embodiment of a magnetic damping structure for use in accordance with the present invention. [Diagram 5] FIG. 5 shows a second embodiment of a magnetic damping structure for use in accordance with the present invention. [Figure 6] FIG. 6 shows a third embodiment of a magnetic damping structure for use in accordance with the present invention. [Figure 7] FIG. 7 is an exemplary representation showing the effect of a magnetic damping structure according to the present invention. [Figure 8] FIG. 8 shows top and cross-sectional views illustrating two different geometric configurations of the magnetic damping structure. [Figure 9] FIG. 9 is a diagram showing an example in which a damping structure is disposed above a magnetic sensing part of a rotation counter. [Figure 10] FIG. 10 is a diagram showing an example in which a damping structure is disposed below the magnetic sensing part of a rotation counter. [Figure 11]FIG. 11 is a diagram showing an example in which an angle sensor and a rotation counter are arranged on a wiring board together with an evaluation electronic circuit. [Figure 12] FIG. 12 is a diagram showing an example in which an angle sensor and a rotation counter are arranged in a common housing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 1 shows the basic design of a magnetic rotary counter, which is commonly used in the prior art and which is also fundamentally maintained in the present invention. An angle sensor 101, a rotary counter 102, and components carrying an evaluation electronic circuit 103 are exemplarily arranged on a wiring board 105. In this example, the angle sensor 101 and the rotary counter 102 are covered by a permanent magnet 100 which can rotate around an axis XX and uniformly capture both components 101 and 102, and are equally captured by its B magnetic field.

[0018] Fig. 2 shows a basic design according to the invention, where a revolution counter 102 is assigned a smart magnetic damping structure 200 integrated therein, i.e. a magnetic damping structure 200 that automatically adjusts its magnetic action. The position of the damping structure 200 in the revolution counter 102 is shown in a first example in Fig. 2. This revolution counter 102 according to the invention can also be mounted directly next to the angle sensor 101 on the wiring board 105. In this case, both sensors are captured by the magnetic field generated by the permanent magnet 100, as shown in Fig. 1.

[0019] A chip with evaluation electronics 103 can also be placed on the wiring substrate 105. For cost reasons it is very advantageous to integrate the angle sensor, the revolution counter and, if necessary, the evaluation electronics in a chip 104 which contains together all the above mentioned components, as shown diagrammatically in figure 3.

[0020] By the action of the smart magnetic damping structure 200, the magnetic window can be significantly enlarged, for example, from the usual 15 mT to 30 mT (without the damping structure 200 according to the invention) to 60 mT to 120 mT when the damping structure 200 is used. In this example, the width of the magnetic window is enlarged from 15 mT to 60 mT, i.e. by a factor of four. The maximum permissible interfering magnetic field is 30 mT when the sensor is operated at 90 mT, and can therefore be enlarged by a factor of six. This significantly and significantly simplifies the use of the rotation counter, since a separate magnetic shielding (not shown here), which was common in the prior art, is simplified or even completely eliminated. This reduces costs and opens up new fields of use for magnetic rotation counters. An essential advantage of this solution according to the invention is that the novel damping structure 200 makes it possible to integrate the angle sensor 101 with the rotation counter 102 and, if necessary, also with the evaluation electronics 103 on one chip 104. Such an integration possibility makes it possible to use permanent magnets 100 with reduced geometric dimensions. This, together with the reduced assembly costs, provides a cheaper solution than was previously possible with the prior art.

[0021] In the following, a special configuration of the magnetic damping structure 200 according to the invention will be described by means of some concrete examples. According to the invention, for use in the damping structure 200, a magnetic material is used which, due to its inherent properties, generates no or only a very small magnetic B field of its own when the external magnetic field B=0 and which generates no or only a small magnetic loss during remagnetization.

[0022] This can be achieved, as shown in Fig. 4 for a first example and two possible arrangements thereof, when the magnetic damping structure consists of sub-layers 402 stacked one on top of the other, magnetized in-plane and aligned antiparallel, with the thickness of each layer being selected so as to magnetically cancel each other. The antiparallel alignment of the layers 402 occurs when the thin ferromagnetic layers 402 are separated by very thin layers 401, for example of copper or ruthenium (Ru). The antiparallel alignment occurs, for example, when the Ru thickness is between 0.8 nm and 1 nm, or when the Cu thickness is about 1 nm or about 2 nm. The B magnetic field B required for a perfect parallel alignment of the magnetization of the regions 402 is sat depends on the thickness and type of the non-magnetic intermediate layer 401 and the material and thickness of the ferromagnetic layer 402. 90 Fe 10 layer and 0.8 nm of Ru, B of about 900 mT sat If the thickness of each layer is increased by a factor of 10, i.e., to 30 nm, B sat The value of B is reduced by a factor of 10, i.e., about 90 mT. This allows the thickness of each ferromagnetic layer 402 to be selected to reduce the sat The desired value of can be easily set. The total B field that can be generated by such a structure at the location of the soft magnetic conductor (see 201 in FIG. 2), which is a component of the GMR or TMR stack for guiding the magnetic domains, depends on the total thickness and its lateral extent. Therefore, a stack arrangement as exemplarily shown in FIG. 4, which is preferred in the present invention, is used. If the thickness of the magnetic layers 402 is constant throughout the stack of layers, the arrangement shown on the right side of FIG. 4 is obtained. Another possible configuration in the context of this example embodiment is the one shown on the left side of FIG. 4, where the upper and lower ferromagnetic layers 402 have only half the thickness of the other ferromagnetic layers. In both configurations shown in FIG. 4, when B=0, and therefore in a completely antiparallel position of all the individual magnetizations of the layers 402, the B field acting outside these layers is equal to zero.

[0023] Another configuration of a magnetic damping structure 200 according to the invention is shown in FIG. 5. In this example, on the left side, a three-layer stack is shown, consisting of a ferromagnetic layer 502 bounded by two non-ferromagnetic layers 501. If the material of layer 501 consists, for example, of platinum (Pt), palladium (Pd), tantalum (Ta) or magnesium oxide (MgO), then a perpendicular magnetization of layer 502 is energetically favorable. In this case, for reasons of stray field energies, adjacent regions are aligned antiparallel in the direction of the normal n of the layer plane. So that in an external magnetic field with B=0, a layer structure is again formed that does not generate a magnetic field B of its own. A 1.5 nm thick Fe 2 ferromagnetic layer surrounded by MgO is magnetized in a ferromagnetic layer 502. 60 Co 20 B 20 In the case of the layer, the saturation field when the magnetic field acts in the plane of the layer has a maximum value of 500 mT. 60 Co 20 B 20 The B field generated in the layers is usually too small to be of any use, so multiple magnetic layers 502, each separated by a non-ferromagnetic layer 501, must be placed one above the other, as illustrated on the right side of FIG.

[0024] A third embodiment of a magnetic damping structure 200 according to the invention is shown in FIG. 6. Here, a collection of small superparamagnetic particles 602, each with a superparamagnetic moment, is shown in a randomly arranged manner embedded in a non-magnetic matrix 601. Such a layer structure has no net magnetic moment in an external magnetic field of B=0. The particles 602 can be, for example, magnetite particles with a diameter of 10 nm to 20 nm. When a magnetic field B is applied to the layer surface, the net magnetization increases linearly with the magnetic field B in the initial vicinity and increases linearly with the magnetic field B. sat Again, a state is reached where all the grains have the same magnetic alignment in the plane. A typical saturation field at room temperature for such a structure is 250 mT.

[0025] The configurations of magnetically antiparallel or magnetically disordered arranged partial regions according to the above-mentioned embodiment examples have in common that they do not generate their own B field or generate only a very small B field in an external magnetic field of B=0. In order to magnetize all partial magnetic regions of a laterally extending structure, such as that provided for the magnetic damping structure 200, in one direction, for example in a plane, a saturation magnetic field B sat If the damping structure described above is made into a certain geometric shape, for example a disk of thickness d and diameter D (see FIG. 8), when a magnetic field is applied to the disk, it will create a stray magnetic field and have stray magnetic energy. This stray magnetic energy also affects the magnetization and can be described using magnetic shape anisotropy. To overcome this stray magnetic energy, a magnetic field B is required to completely align the disk in the magnetic field direction. SH sat The saturation magnetic field strength B SH sat is determined by the ratio of the lateral extent of the disk to the total thickness of the magnetic layer and the value of the saturation magnetization of the ferromagnetic material.

[0026] When the magnetic layer is made of a layer stack as described in the above embodiment, both of the above effects are additive. This is because in order to align all the magnetic regions (402 or 502 or 602) uniformly in the plane, a larger B field B res This means that the magnetic field required for this is B SH sat and B sat Each value of the formula B res sat =B SH sat +B sat It is obtained by adding according to

[0027] The magnetic damping structure 200 according to the present invention is made of 15 nm CoFe / 0.8 nm Ru / [30 nm CoFe / 0.8 nm Ru] 40 For example, a 20-nm thick, 1000-μm diameter disk consisting of a 15-nm CoFe layer stack is used. SH sat =35mT and Bsat = 90mT. Therefore, B SH sat and B sat B is the sum of res sat is 125mT.

[0028] In the following, the operation of the smart magnetic damping structure 200 formed as a disk, subjected to a uniform B magnetic field, will be described with reference to FIG. min and B max The values ​​of θ and θ are plotted as horizontal lines. If this disk 200 is placed in an external magnetic field so that the B field is aligned parallel to the disk surface, the B field does not change at a position far away from the disk (the dashed line in FIG. 7 indicated by "2"). The B field shown by the thick black line indicated by "1" is obtained directly above or below the disk at the center of the disk. As long as the disk 200 is not magnetically saturated, i.e., the B res sat In the case of , the B field increases linearly at this point, but much slower than the externally applied B field. Therefore, the thick line "1" is the B min "4" and B max The crossing of both lines of "3" occurs only at much larger values ​​of B. As a result, the magnetic window is expanded from the original 20mT-40mT to a magnetic window B of 60mT-120mT. This means that a three times wider window is available for rotation sensor applications. This also improves the stability against external or interfering magnetic fields, which also brings great benefits for applications.

[0029] ​In the case of the circularly configured damping structure 200 described here (corresponding to FIG. 8 on the left), the magnetic behavior of the disk is the same in all directions in the plane. That is to say, the B-field acting above and below the damping structure is the same in terms of magnitude in all directions of the B-field in the plane. This is the desired behavior for a spirally configured rotary counter known from German patent application DE102008063226A1. This is different when using a so-called closed-loop structure, as described, for example, in European patent application EP3066421B1. This geometry uses a spiral whose two ends are connected to each other. This results in a crossing of the magnetic field lines. At the crossing, the width of the magnetic conductor increases by about 45% in the direction of the crossing diagonal. As a result, the magnetic window in the 0° direction is different from the magnetic window in the 45° direction. Such differences can be compensated if the damping structure is no longer circular, but has a shape as shown on the right side of FIG. 8. Therefore, according to the invention, for a damping structure for a rotary counter operating on the basis of a closed loop structure (European patent application EP 3066421 B1), it is proposed that the damping structure is no longer formed circularly, but is varied in a selected direction as shown in the right part of FIG. 8. In this way, the differences in the B field in different directions can be easily accommodated by choosing a geometry of the damping disk whose lateral extent differs depending on the direction. Increasing the diameter of the disk by 20% in one direction reduces the B field in this direction. SH sat The value of decreases by 20%. See for example the dual geometry of the smart damping disk shown on the right side of Figure 8. On the left side of Figure 8, B SH sat is the same in all directions and the magnetic behavior is isotropic. In the geometry shown on the right side of Figure 8, the saturation magnetic field B SH sat is the same in the X and Y directions, but the saturation magnetic field B exists at ±45° SH satThe damping structure 200 is different from the conventional rotary counter. The direct arrangement of the damping structure 200 on the magnetically sensitive part 201 of the rotary counter is exemplarily explained with the aid of the figures 2, 9 and 10. Figure 2 shows a schematic cross-section of a rotary counter chip. The silicon substrate 204 with the functional part of the rotary counter is glued to the base plate of the housing 206 of the rotary counter. The electrical connection of the bond pad structures 205 provided on the silicon substrate 204 of the rotary counter is realized by means of bonding wires 207 connecting the bond pads 205 on the silicon substrate 204 with the bond pads 208 of the housing. Solder contacts 211 are used to solder the chip to the wiring board 105 (see figure 3). The structures provided on the silicon substrate include the functional structure 201 of the rotary counter, the metallization structure 202 and the bond pad structures 205. These structures are at least partially covered with an insulating layer 203. The damping structure 200 according to the invention is provided only in a partial area of ​​the silicon substrate and completely covers, with a slight lateral overhang, the structure 201 associated with the function of the rotation counter, so that its total lateral length can be smaller than the surface of the silicon substrate 204. An insulating layer 209, which also functions as a planarization layer, can be located below the damping layer 200.

[0030] The position of the damping structure 200 can be located above or below the structure 201, as shown in Figures 9 and 10 (circle mark 210 in Figure 2). This is related to the fact that the geometrical distance between these two positions is small compared to the distance to the permanent magnet, so that the B magnetic field generated by the damping structure 200 is almost the same above and below the damping structure 200. The insulating layer, as described below, is generally only a few μm thick, the GMR layer or TMR layer is only about 70 nm, and the distance from 201 to 100 is always a minimum size of 1 mm.

[0031] Based on FIG. 2, it can be seen that the lateral extent of the damping layer is in any case less than the space required for the bond pads. Since the thickness of the insulating intermediate layers 203 and 209 is in the range of only a few μm, the damping structure only needs to extend laterally by a few μm to a few tens of μm beyond the magnetically sensitive structure 201 of the rotation counter in order to sufficiently reduce the influence of effects that occur only at the ends of the damping structure. Generally, in all embodiments according to the invention, in terms of the lateral extent, the damping layer 200 protrudes laterally by no more than 30% relative to the soft magnetic GMR or TMR structure 201 of the rotation counter 102. This shows that the new constructional form does not exceed the conventional constructional form in terms of space required. Moreover, by now encapsulating the angle sensor and the rotation counter together, instead of encapsulating them separately, it is possible to place them even closer together (spacing <200 μm), because, as shown in FIG. 2, the extent of the damping structure 200 is significantly smaller than the rotation counter 102. It is also possible to place the revolution counter close to the angle sensor (spacing <200 μm) without common encapsulation, without losing the advantages mentioned above. As a result, by placing the revolution counter 102 close to the angle sensor 101, the permanent magnet 100 can be made smaller, just like in the case of common encapsulation of both components, which significantly reduces the size of the entire system and also reduces the cost of the permanent magnet.

[0032] The manufacturing technique for the damping layer 200, in the system shown in Figures 4 and 5, can be by a sputtering process and can therefore be carried out in the same manufacturing process as the manufacture of the rotary counter body.

[0033] The proposed damping structure 200 achieves significantly improved stability of the magnetic rotary counter against interfering magnetic fields, thereby reducing the cost of magnetic shielding that would otherwise be required during use, and even making it possible to dispense with the use of magnetic shielding altogether.

[0034] Furthermore, due to the limited lateral extent of the damping layer, as shown in figures 11 and 12, the proposed solution allows the integration of the angle sensor, the revolution counter and possibly the evaluation electronics (shown in figure 3) in a common hermetic housing 213 that contains all the components. The invention allows the determination of a spacing between the angle sensor 101 and the revolution counter 102 in the order of less than 500 μm. For the housing 213, commercially available chip housings can be used. This reduces the design costs of the overall system and allows for a compact solution, which can save considerable costs. The invention also allows the use of smaller permanent magnets 100, which further reduces the overall system costs. Similarly, the invention allows the widening of the magnetic window of the revolution counter 102, which relaxes the tolerance requirements for the permanent magnets 100. [Explanation of symbols]

[0035] 100 Permanent Magnets 101 Angle Sensor 102 Rotation Counter 103 Evaluation Electronic Circuit 104 Chip with angle sensor and rotation counter 105 Wiring board 200 Damping Structure 201 Soft magnetic conductors as components of GMR or TMR stacks for guiding magnetic domains 202 Metallization 203 Insulating Interlayer 204 Silicon Substrate 205 Contact with contact opening 206 Chip base (housing) 207 Bond Wire 208 Contact pads in chip housing 209 Planarization layer 210 yen sign (see Figures 9 and 10) 211 SMD bond pads 212 Soft Magnetic Conductors as Components of GMR or TMR Angle Sensors 213 Housing 401 Non-ferromagnetic thin layer 402 Ferromagnetic thin layer 501 Layer 502 that generates perpendicular magnetic anisotropy 502 Ferromagnetic thin layer 601 Non-magnetic matrix 602 (supernormal) magnetic particles

Claims

1. 1. A magnetic system for revolution counting with improved stability against interfering magnetic fields, comprising an angle sensor (101) for detecting the magnetic field direction of a permanent magnet (100) which captures both an angle sensor (101) and a revolution counter (102), the latter being formed by a GMR or TMR revolution counter of known construction, the angle sensor (101) and the revolution counter (102) being arranged adjacent to one another in a common housing (213) and / or on a common wiring board (105), characterized in that a magnetic damping structure (200) for automatically adjusting the magnetic effect is assigned to the revolution counter (102), the magnetic damping structure (200) being made up of magnetically antiparallel configurations or randomly arranged partial regions, other than a structure made of a homogeneous soft magnetic material, which has no magnetic field of its own or only a very slight magnetic field when the external magnetic field is zero.

2. A magnetic system for revolution counting having improved stability against interfering magnetic fields, comprising an angle sensor (101) for detecting the magnetic field direction of a permanent magnet (100) which captures both an angle sensor (101) and a revolution counter (102) described below, said revolution counter (100) being formed by a GMR or TMR revolution counter of known structure, said angle sensor (101) and said revolution counter (102) being arranged adjacent to each other in a common housing (213) and / or on a common wiring board (105), said revolution counter (102) being assigned a magnetic damping structure (200) which automatically adjusts its magnetic action, said magnetic damping structure (200) being other than a structure made of a homogeneous soft magnetic material and which has no magnetic field of its own or only a very slight magnetic field when the external magnetic field is zero, The magnetic damping structure (200) is formed by a layer stack in which ferromagnetic sublayers (402) are stacked one on top of the other, magnetized in a plane and aligned antiparallel, the thicknesses of the layers being selected so as to magnetically offset each other, and the ferromagnetic sublayers (402) are separated by thin non-ferromagnetic layers (401).

3. A magnetic system for revolution counting having improved stability against interfering magnetic fields, comprising an angle sensor (101) for detecting the magnetic field direction of a permanent magnet (100) which captures both an angle sensor (101) and a revolution counter (102) described below, said revolution counter (100) being formed by a GMR or TMR revolution counter of known structure, said angle sensor (101) and said revolution counter (102) being arranged adjacent to each other in a common housing (213) and / or on a common wiring board (105), said revolution counter (102) being assigned a magnetic damping structure (200) which automatically adjusts its magnetic action, said magnetic damping structure (200) being other than a structure made of a homogeneous soft magnetic material which has no magnetic field of its own or only a very slight magnetic field when the external magnetic field is zero, The magnetic damping structure (200) is formed by a layer stack consisting of at least one ferromagnetic layer (502) covered on both sides by two non-ferromagnetic layers (501), the ferromagnetic layer (502) having a perpendicular magnetization parallel to the normal (n) of the ferromagnetic layer (502), and adjacent magnetic field regions are formed so as to have antiparallel directions.

4. A magnetic system for revolution counting having improved stability against interfering magnetic fields, comprising an angle sensor (101) for detecting the magnetic field direction of a permanent magnet (100) which captures both an angle sensor (101) and a revolution counter (102) described below, said revolution counter (100) being formed by a GMR or TMR revolution counter of known structure, said angle sensor (101) and said revolution counter (102) being arranged adjacent to each other in a common housing (213) and / or on a common wiring board (105), wherein a magnetic damping structure (200) for automatically adjusting the magnetic action is assigned to said revolution counter (102), said magnetic damping structure (200) being other than a structure made of a homogeneous soft magnetic material and which has no magnetic field of its own or only a very slight magnetic field when the external magnetic field is zero, A magnetic system characterized in that the magnetic damping structure (200) is formed by a layer system consisting of a collection of small superparamagnetic particles (602) each having a superparamagnetic moment and embedded in a non-magnetic matrix (601) in a disordered arrangement.

5. A magnetic system according to any one of claims 1 to 4, characterized in that, in terms of lateral extent, the magnetic damping structure (200) protrudes laterally by no more than 30% relative to the soft magnetic GMR or TMR structure (201) of the rotation counter (102).

6. A magnetic system described in any one of claims 1 to 4, characterized in that the magnetic damping structure (200) is arranged above or below the sensitive layer (201) of the rotation counter (102).

7. A magnetic system as described in claim 5, characterized in that the magnetic damping structure (200) is arranged above or below the soft magnetic GMR or TMR structure (201) of the rotation counter (102).

8. A magnetic system described in any one of claims 1 to 7, characterized in that, depending on the type of rotation counter (102) in which the magnetic damping structure (200) is used, it is given a shape that deviates from circular in a planar view to take into account the effects of shape anisotropy.

9. A magnetic system as described in claim 1, characterized in that the spacing between the angle sensor (101) and the rotation counter (102) is determined to be on the order of less than 500 μm, and at least both components are hermetically sealed by the common housing (213).

10. A magnetic system as described in claim 1, characterized in that the spacing between the angle sensor (101) and the rotation counter (102) is determined to be on the order of less than 500 μm, and at least both of these components, together with the evaluation electronic circuit (103), are hermetically sealed in the common housing (213).

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