A magnetic system for counting revolutions with improved resistance to interference magnetic fields.

Abstract

This invention relates to a magnetic system for counting revolutions with improved resistance to interference magnetic fields. The objective is to provide a system that can be used in a magnetic field region (field region B) that significantly exceeds the magnetic field regions typically used according to the prior art, wherein the width ΔB of the magnetic window, i.e., the difference between the lower and upper limits of the allowable magnetic field B, is as large as possible. This objective is achieved by using an angle sensor to determine the field direction of the magnetic field covered by a permanent magnet and a revolution counter (102), wherein the revolution counter is constructed of a known type of GMR or TMR revolution counter, and the two sensors are arranged side-by-side in a common housing and / or on a common circuit board. The revolution counter (102) is characterized by having a magnetically damped structure (200) that automatically adapts to its magnetic action, except for the portion made of a homogeneous soft magnetic material, which has no self-magnetic field or only a negligible self-magnetic field when the external magnetic field is zero.

Description

Background Technology

[0001] Magnetic sensors can detect the characteristics of a magnetic field, such as its direction. One example of a magnetic sensor is an angle sensor. Other types of magnetic sensors can determine how often a magnetic field rotates. This tachometer can be, for example, a GMR tachometer or a TMR tachometer, as is well known in the prior art. In addition to the sensor function, the sensor typically also includes a storage function, that is, it stores, for example, how often a permanent magnet rotates. The determination of the number of rotations is primarily done in conjunction with an angle sensor, which determines the precise direction of the magnetic field, according to the prior art. Therefore, a measurement system for measuring angles, for example, in the range of 0° to 3600°, can include, for example, an angle sensor for determining angles between 0° and 180° (e.g., using an AMR (anisotropic magnetoresistive angle sensor)) or (using a GMR or TMR angle sensor, a Hall sensor, or another angle sensor) between 0° and 360°; and a tachometer that allows the determination of the number of rotations, which in the aforementioned example is 0 to 10. The two sensors, namely the angle sensor and the tachometer, are designed as separately manufactured components and are typically arranged side-by-side on a circuit board. Additionally, as already described, components containing evaluation electronics can be arranged on the circuit board. As described, for example, in EP 3387387 B1, these components can evaluate the signals from the two sensors, provide power supply voltage, and also perform fault monitoring. A rotating permanent magnet can be positioned above the angle sensor and the tachometer, the lateral extension of which is determined such that stray magnetic fields below the permanent magnet sufficiently surround the two sensors mentioned. However, a linear arrangement of magnets, for example, acting as a magnetic ruler, also generates a rotating magnetic field as the tachometer moves past the magnetic ruler; this magnetic field can be used by means of the tachometer to achieve distance measurement.

[0002] The specific arrangement of the two components (angle sensor and tachometer) is influenced by their characteristics, both of which are simultaneously covered by the magnetic field of a permanent magnet. These two components can, for example, be arranged side-by-side on a circuit board. In this geometry, the two components experience the same magnetic flux B, generated by the permanent magnet in the plane of the components.

[0003] As described below, the following arrangement has the advantage that the magnetic flux B at the location of the tachometer is less than the magnetic flux at the location of the angle sensor. This can be achieved, for example, by arranging the two components on opposite sides of a circuit board a few millimeters thick. This increases the thickness of the circuit board by increasing the distance between the permanent magnet and one of the components. If the tachometer is arranged below the circuit board, the magnetic flux B at the location of the tachometer is less than the magnetic flux at the location of the angle sensor due to the increased distance, and the angle sensor experiences the field B of the permanent magnet more closely. Another possible arrangement can be achieved by a magnetic shielding layer, in which the field B at the location of the tachometer is less than the field B at the location of the angle sensor, and the magnetic shielding layer is arranged above the tachometer. The two sensors can then be arranged on the same side of the circuit board. However, the angle sensor and the tachometer must have a larger distance in this case, because otherwise the shielding layer will also reduce the field B at the location of the angle sensor in an undesirable manner.

[0004] The magnetic angle sensor achieves its highest accuracy when a large value (≥100 mT) of magnetic flux B generated by the permanent magnet is present at the sensor's location. In contrast, the tachometer can only provide an error-free determination of the number of revolutions within a magnetic window, which can extend, for example, from 15 mT to 30 mT. To better determine the angle, for example, to 0.05° using an angle sensor, a sensor magnetic field of at least 100 mT is required. The tachometer, however, allows the sensor magnetic field to be only 23% of the optimal value for the angle sensor, i.e., 23 mT, so that it is ideally located at the center of the B magnetic field region, in which the tachometer operates error-free.

[0005] Due to the different requirements for the magnetic fields affecting the two necessary components, the previously envisioned arrangement has the following drawbacks:

[0006] The geometrically adjacent arrangement of two components on an unshielded circuit board cannot determine the angle with high accuracy because the tachometer typically determines the B field at the location of the angle sensor to be 23 mT, otherwise the tachometer cannot operate within its predetermined magnetic window.

[0007] The arrangement on two opposing sides of a thicker circuit board allows the two sensors to operate in the desired B-magnetic field region of the two sensors. However, the thickness of the circuit board must be precisely matched to the sensor magnets and is altered, for example, when using permanent magnets with different geometries (e.g., for smaller measurement systems). Integration of the two sensors into the chip housing is not feasible in the described embodiment with a predetermined small structural size.

[0008] While the use of a magnetic shielding layer made of uniform soft magnetic material above the tachometer enables the arrangement of two sensors on the same side of the circuit board and their respective operation in the optimal B-field region, integration in a common small chip housing is impossible due to the required spacing between the angle sensor and the magnetic shielding layer located above the tachometer. This is because the shielding layer must first extend laterally beyond the tachometer by approximately 60% and must also be laterally separated from the angle sensor by a spacing of at least 50% of the lateral dimension of the magnetic shielding layer. Thus, the shielding layer's effect is essentially limited to the tachometer and only negligibly affects the B-field at the location of the angle sensor.

[0009] In particular, a common feature of the two arrangements that do not use a shielding layer is that the influence of external interfering magnetic fields affecting the sensor system must be sufficiently reduced through appropriate structural measures. Such interfering fields can be generated, for example, when a large current flows near the sensor system. Another possibility for the emergence of interfering fields lies in the use of objects with bonded magnets near the sensor system, such as lighting fixtures.

[0010] Therefore, for all applications, the design of the sensor system must ensure, through the following structural measures, that the B-field acting on the tachometer is always within a specific predetermined area of ​​the magnetic window during the operation of the sensor system.

[0011] This is illustrated in the following example, where, for instance, a B-field in the range of 20-25 mT from the sensor magnet acts on the tachometer under real-world conditions. This range depends, for example, on the temperature dependence of the sensor magnet's magnetization and on possible undesirable mechanical movements of the permanent magnet during operation, which slightly alter the distance between the magnet and the plane containing the tachometer. This means that, in the case of a maximum permissible B-field of 30 mT, the entire system must be designed so that the interfering magnetic field acting on the entire system at the location of the tachometer sensor is always below 5 mT. When this cannot be ensured under the sensor's operating conditions, it must be achieved through additional shielding measures. This typically requires high structural and material costs and is associated with significant additional expenses.

[0012] To improve the thrombopus field immunity of the thrombopus meter, a soft magnetic shielding layer is used at the thrombopus meter location to adjust the B-field at the thrombopus meter's location to the thrombopus field's magnetic window. For this purpose, the magnetic shielding layer, for example implemented as a soft magnetic disk, must have a vertical spacing of approximately 30% of the sensor's lateral extension. The shielding layer itself must have a lateral extension of at least 4 mm and a thickness of 0.5 mm in the case of a 2 mm lateral extension of the thrombopus meter to ensure the B-field within the thrombopus meter's region as required. Because the angle sensor cannot be covered by the shielding layer to achieve its high measurement accuracy, the angle sensor must have a minimum spacing of approximately 6 mm relative to the thrombopus meter. This makes a laterally narrow arrangement of the two sensors, or integration of the angle sensor, thrombopus meter, and evaluation electronics on a chip and in a common housing of typical types, impossible. Simultaneously, the permanent magnet must be implemented with a laterally enlarged size, thereby placing the two sensors in a uniform region of the B-field. However, the large permanent magnet introduces a significant cost share into the entire sensor system. If the angle sensor and thrombopus sensor are positioned very close to each other, a smaller permanent magnet can be used, thereby saving costs. If the angle sensor and tachometer can also be integrated into the housing, the overall price is reduced compared to using the sensors in a separate housing. Furthermore, assembly costs are saved.

[0013] As described in DE 10 2008 063 226 A1, a tachometer comprises a magnetic conductor in which domain walls move. The magnetic conductor may be a portion of a GMR (Giant Magnetoresistance) stack or a TMR (Tunneling Magnetoresistance) stack and is manufactured in a helical shape. The magnetic window of this helix can be adjusted, for example, by the width of the soft magnetic structure within the stack. A narrower width allows for larger lower and upper limits of the magnetic window. For a tachometer intended to operate at 100 mT, the structural width must be reduced to the previously used ~350 nm structural width. 1 / 4. However, the challenge lies in replacing the traditional 350nm fabrication method with structures having widths below 100nm. When using photolithography for structuring, a major risk is that the unavoidable roughness of the magnetic conductor significantly reduces the yield of the components. Summary of the Invention

[0014] The objective of this invention is to provide a magnetic system for counting revolutions with improved resistance to interference magnetic fields, which can be used in a magnetic field region (field region B) that significantly exceeds the magnetic field region typically used in the prior art. Furthermore, the width ΔB of the magnetic window, i.e., the difference between the lower and upper allowable B values, should be as large as possible.

[0015] This task is solved by the distinguishing feature of claim 1. The essence of the invention lies in the fact that the tachometer is configured with a magnetically damped structure that automatically adapts to its magnetic action, except for the portion made of a homogeneous soft magnetic material, which has no self-magnetic field or only a negligible self-magnetic field when the external magnetic field is zero. Advantageous designs are described in the dependent claims. Attached Figure Description

[0016] The following embodiments are used to specifically illustrate the present invention. In the accompanying drawings:

[0017] Figure 1 The arrangement of the angle sensor and tachometer is shown according to the usual arrangement in the prior art;

[0018] Figure 2 A basic embodiment according to the present invention is shown;

[0019] Figure 3 Exemplary integration of an angle sensor, a tachometer, and, if necessary, evaluation electronics within a chip is shown;

[0020] Figure 4 A first implementation possibility of the magnetic damping structure used according to the present invention is shown;

[0021] Figure 5 A second implementation possibility of the magnetic damping structure used according to the present invention is shown;

[0022] Figure 6 This illustrates a third possible implementation of the magnetic damping structure used according to the present invention;

[0023] Figure 7 An exemplary view showing the function of the magnetic damping structure according to the present invention;

[0024] Figure 8 Two different geometric configurations of the magnetic damping structure are illustrated exemplarily in top view and cross-sectional view;

[0025] Figure 9 An exemplary arrangement of the damping structure above the magnetically sensitive portion of the tachometer is shown;

[0026] Figure 10 An exemplary arrangement of the damping structure below the magnetically sensitive portion of the tachometer is shown;

[0027] Figure 11 An exemplary arrangement of the angle sensor and tachometer along with evaluation electronics on a circuit board is shown; and

[0028] Figure 12 An exemplary arrangement of the angle sensor and tachometer in a common housing is shown. Detailed Implementation

[0029] Figure 1 First, a basic embodiment of a magnetic tachometer commonly found in the prior art is shown, and this basic embodiment will also be retained in principle in this invention. An angle sensor 101, a tachometer 102, and components with evaluation electronics 103 are exemplarily arranged on a circuit board 105. In this example, the angle sensor 101 and the tachometer 102 are covered by a permanent magnet 100, which uniformly covers the two components 101 and 102 and is rotatable about the axis XX of the permanent magnet, and the angle sensor and the tachometer are covered in the same manner by the B magnetic field of the permanent magnet.

[0030] Figure 2 A basic embodiment according to the present invention is shown. Here, the tachometer 102 is internally integrated with a magnetic damping structure 200, which is intelligent, that is, automatically adapts to magnetic action. Figure 2 The first example shows the position of the damping structure 200 inside the tachometer 102. The tachometer 102 according to the invention can also be mounted directly on the circuit board 105 next to the angle sensor 101. Thus, the two sensors are positioned as if... Figure 1 As shown in the figure, it is covered by the magnetic field generated by the permanent magnet 100.

[0031] The chip with evaluation electronics 103 can also be arranged on the circuit board 105. It is highly advantageous for cost reasons that the angle sensor, tachometer, and, if necessary, evaluation electronics are integrated into a chip 104 that collectively contains all the aforementioned components, as in... Figure 3 As illustrated schematically.

[0032] The intelligent magnetic damping structure 200 allows for a significant increase in the magnetic window, for example, from the conventional 15-30 mT (without the damping structure 200 according to the invention) to 60-120 mT with the damping structure 200. In this example, the width of the magnetic window is increased from 15 mT to 60 mT, a fourfold increase. When the sensor operates at 90 mT, the maximum permissible interfering magnetic field can be 30 mT, thus increasing by approximately a factor of 6. This significantly simplifies the use of the tachometer, as the previously common separate magnetic shielding layer (not shown) becomes simpler or even entirely redundant. This saves costs and opens up new application areas for magnetic tachometers. A key advantage of this solution according to the invention is that the angle sensor 101, tachometer 102, and, if necessary, evaluation electronics 103 can be integrated into a chip 104 via the novel damping structure 200. This integration capability allows for the use of a permanent magnet 100 with a reduced geometry. This, along with the reduction in assembly costs, results in a more cost-effective solution compared to previous solutions based on existing technologies.

[0033] The following will illustrate a specific design scheme of the magnetic damping structure 200 according to the present invention with the aid of several specific examples. According to the present invention, the damping structure 200 shall use a magnetic material that, based on its inherent properties, does not generate or only generates a very small self-field (B field) when the external magnetic field is B=0, and does not generate magnetic loss or only generates a small magnetic loss when the magnetic material is repeatedly magnetized.

[0034] When the magnetic damping structure is composed of stacked, planar, antiparallel sublayers 402, the thickness of which is chosen such that the sublayers magnetically compensate for each other, this can be achieved as in Figure 4 The implementation is shown in the first example and two subsequent possible arrangements. When the thin ferromagnetic layer 402 is separated by an ultrathin layer 401 of, for example, copper or ruthenium, an antiparallel orientation of layer 402 is produced. For example, an antiparallel orientation is produced when the thickness of Ru is between 0.8 nm and 1 nm, or the thickness of Cu is about 1 nm or about 2 nm. A perfectly parallel orientation for magnetizing region 402 requires a B-field B0. sat This is related to the thickness and type of the non-magnetic intermediate layer 401, as well as the material and thickness of the ferromagnetic layer 402. For a 3nm thick Co... 90 Fe 10 The layer and 0.8nm Ru require ~900mT of B. sat If the thickness of a single layer increases tenfold, i.e., to 30 nm, then B satThe value is reduced to 1 / 10, i.e., ~90mT. B can thus be easily adjusted by selecting the thickness of a single ferromagnetic layer 402. sat The expected value. This structure, which is part of the GMR or TMR stack used to guide magnetic domains, is located at the position of the soft magnetic conductor (see...). Figure 2 The total B-field generated by 201) is related to the total thickness and the lateral extension of the structure. Therefore, according to the present invention, it is preferable to use, as exemplarily shown, in... Figure 4 The stack is arranged in this manner. If the thickness of the magnetic layer 402 is constant throughout the entire layer stack, then the desired effect is achieved. Figure 4 The arrangement shown on the right.

[0035] exist Figure 4 The left side shows another possible arrangement within the framework of this embodiment, in which the upper ferromagnetic layer and the lower ferromagnetic layer 402 have only half the thickness of the other ferromagnetic layer. According to... Figure 4 In both configurations, the outward B field of the layer is equal to zero when B = 0 and thus in the completely antiparallel position of all individually magnetized layers 402.

[0036] exist Figure 5 The diagram illustrates another design of the magnetic damping structure 200 according to the invention. In this example, a three-layer stack is shown on the left, comprising a ferromagnetic layer 502 bounded by two non-ferromagnetic layers 501. If the material of layer 501 is, for example, Pt, Pd, Ta, or MgO, then the perpendicular magnetization of layer 502 is energy-preferred. This is because the magnetic stray field energy causes adjacent regions to be antiparallel in the direction of the normal n to the layer plane. Thus, a layer structure that does not generate its own B field exists when the external magnetic field B = 0. For a 1.5 nm thick Fe encased in MgO... 60 Co 20 B 20 The layer, when subjected to a magnetic field in its plane, exhibits a saturation field of up to 500 mT. A 1.5 nm thick Fe layer oriented in the plane... 60 Co 20 B 20 The B-field generated by the layer is mostly too small for most applications. Therefore, multiple magnetic layers 502 must be arranged in an overlapping manner, with each magnetic layer separated by a non-ferromagnetic layer 501, as exemplarily in... Figure 5 As shown on the right.

[0037] Figure 6A third embodiment of the magnetic damping structure 200 according to the invention is shown. Here, an assembly of small superparamagnetic particles 602 is schematically shown, each superparamagnetic particle possessing its own superparamagnetic moment and randomly oriented and embedded in a nonmagnetic matrix 601. The layer structure has no net magnetic moment when the external magnetic field B = 0. For example, magnetic particles with a diameter of 10 nm to 20 nm can be used as particles 602. With the application of a magnetic field B in the layer plane, the net magnetization increases linearly with the field B in the nearest vicinity and increases further with the field B. sat The structure then reaches a state in which all particles have the same magnetic orientation in the plane. The typical saturation field for this structure is 250 mT at room temperature.

[0038] In other words, the common feature of the configurations according to the preceding embodiments, which consist of magnetically antiparallel or magnetically disordered oriented particle regions, is that these particle regions do not generate or only generate a negligible small self-field (B-field) when the external magnetic field B = 0. To magnetize all the magnetic portions of a structure, for example, provided for the lateral extension of the magnetic damping structure 200, in one direction, for example, in a plane, a saturation magnetic field B is required. sat .

[0039] If the aforementioned damping structure is made into a disc with a defined geometry, such as a disk with a thickness d and a diameter D (see...), then... Figure 8 When a magnetic field is applied, the disk generates a stray magnetic field and possesses stray field energy. This stray field energy, in turn, affects magnetization and can be described by means of magnetic shape anisotropy. A field B is needed to eliminate this stray field energy. SH sat Used for complete orientation in the direction of the magnetic field. Saturation field strength B SH sat It is determined by the ratio of the lateral extension of the disk to the total thickness of the magnetic layer and the value of the saturation magnetization of the ferromagnetic material.

[0040] If the magnetic layer is composed of stacked layers as described in the preceding possibilities, then the two aforementioned effects are additive. This means that a larger B-field must be applied in the plane. res This ensures that all magnetic regions (402, 502, or 602) are uniformly oriented in the plane. According to formula: B res sat =B SH sat +B sat The field required for this is B SH sat The single value and B sat It is obtained by adding the individual values.

[0041] If a circular disk with a thickness of, for example, 20 μm and a diameter of 1000 μm is used for the magnetic damping structure 200 according to the invention, it is composed of 15 nm CoFe / 0.8 nm Ru / [30 nm CoFe / 0.8 nm Ru]. 40 The B layer is composed of 15nm CoFe layers. SH sat =35mT and B sat =90mT. Therefore, B res sat As B SH sat With B sat The total is 125mT.

[0042] The following should be used with the help of Figure 7 The function of the intelligent magnetic damping structure 200, designed as a disk, is described, wherein the magnetic damping structure is subjected to a uniform B-field. The B-field at 102 revolutions is marked on the Y-axis with a horizontal line. min and B max The value of B. If the disk 200 is brought into an external magnetic field such that the B field is oriented parallel to the disk surface, then the B field does not change over a large distance from the disk. Figure 7 (The dotted line marked with "2" in the diagram). Directly above or below the disk at the center, the B field is obtained as shown by the bold black line marked with "1". This is possible as long as the disk's magnetism is not saturated at 200°, i.e., B... res sat The B field increases linearly at this location, but much more slowly than the B field from external forces. Therefore, the bold line "1" differs from the B field measured by the tachometer only at much larger B values. min “4” and B max The two lines of the "3" result in the magnetic window, originally 20mT to 40mT, being increased to a magnetic B window of 60mT to 120mT. This means that a three-fold wider window is provided for the speed sensor in the aforementioned application. This also improves the stability against external or interfering fields, which is extremely advantageous for the application.

[0043] For the circular design scheme of the damping structure 200 described herein (corresponding to...) Figure 8 (On the left), the magnetic properties of the disk are the same in all directions in the plane; that is, the B-field acting above and below the damping structure is numerically the same in all directions in the plane. This is a desirable characteristic for a tachometer with a spiral design as known from DE102008063226.

[0044] ​This is different in the case of using, for example, the so-called ClosedLoop structure described in patent EP 30664218 B1. The geometry uses a spiral, with the two ends of the spiral connected to each other. This results in a crossing of magnetic circuitry. At the crossing, the width of the magnetic conductor increases by approximately 45% in the direction of the diagonal of the crossing. This causes the magnetic window in the 0° direction to differ from the magnetic window in the 45° direction. When the damping structure is no longer circular, but has a shape similar to... Figure 8 When the shape shown on the right is used, this difference can be compensated for. According to the invention, therefore, for a damping structure used in a tachometer operating based on a ClosedLoop structure (EP 30664218 B1), the damping structure is no longer designed in a circular shape but rather as if... Figure 8 As shown on the right, the direction is changed in the selected direction. In this way, the difference in the B-field in different directions can be easily adjusted by selecting the geometry of the damping disc, in which the lateral extension is different in different directions. If the disc increases in diameter by 20% in one direction, then B... SH sat The value decreases by 20% in this direction. As an example, in... Figure 8 The dual geometry of the intelligent damping disc on the right side. Figure 8 Left side of the middle, B SH sat It is the same in all directions; its magnetic properties are isotropic. Figure 8 In the geometry shown on the right, the saturation field B SH sat The same applies in the X and Y directions, however, a saturation field B exists at + / -45°. SH sat They are different.

[0045] The arrangement of the damping structure 200 adjacent to the magnetically sensitive part 201 of the tachometer is exemplarily shown in... Figure 2 , 9 This is explained in section 10. Figure 2 A schematic cross-section of the tachometer chip is shown. The silicon substrate 204, housing the functional parts of the tachometer, is bonded to the base plate of the tachometer housing 206. Electrical connections of the pad structures 205 applied to the Si substrate 204 are achieved via bonding wires 207 that connect the pads 205 on the Si substrate 204 to the pads 208 on the housing. To solder the chip to the circuit board 105 (see...),... Figure 3The structure applied to the Si substrate includes a tachometer functional structure 201, a metallized structure 202, and pads 205. The structure is at least partially covered by an insulating layer 203. According to the invention, the damping layer 200 is applied only to a portion of the Si substrate and completely covers the tachometer-related functional structure 201 with a small lateral overhang. Therefore, the total lateral extension of the damping layer can be less than the area of ​​the Si substrate 204. Similarly, the insulating layer 209, which also serves as a planarization layer, can be located below the damping layer 200.

[0046] The layers of the damping structure 200 can be like in Figure 9 and 10 (from) Figure 2 As shown in the circular segment 210, it is arranged not only above but also below structure 201. This is related to the fact that the B-field generated by the damping structure 200 is almost the same above and below the damping structure 200 because the geometric spacing between these two locations is smaller than the spacing with the permanent magnet. The insulating layer, as given below, is only a few μm thick, the GMR or TMR layer is only about 70 nm, and the spacing between 201 and 100 is always a minimum of 1 mm.

[0047] from Figure 2 As can be seen from the diagram, the damping layer occupies a laterally smaller area than would normally be required for the pads. Because the thicknesses of the insulating layer and intermediate layers 203 and 209 are only a few μm, the damping structure must also extend laterally beyond the magnetic sensing structure 201 of the tachometer by only a few μm to tens of μm to minimize the effects generated only at the ends of the damping structure. Typically, applicable to all embodiments of the invention, the damping layer 200 extends laterally beyond the soft magnetic GMR or TMR structure 201 of the tachometer 102 by no more than 30%. Thus, the new structural form does not exceed the space requirements of the previous structural form, and now, even when the angle sensor and tachometer are not packaged separately, the co-package of the two sensors allows for a closer arrangement (pitch < 200 μm), because... Figure 2 The extension of the damping structure 200 shown is significantly smaller than that of the tachometer 102. Without co-encapsulation, the tachometer can also be arranged closely adjacent to (pitch < 200 μm) the angle sensor without losing the aforementioned advantages. As a result, by placing the tachometer 102 closely adjacent to the angle sensor 101, a smaller permanent magnet 100 can be achieved as if both parts were co-encapsulated in a common housing, which in turn leads to a significantly smaller overall system and a reduced cost for the permanent magnet.

[0048] For Figure 4 and 5 The manufacturing technology of the damping layer 200 of the system shown can be achieved through a cathode sputtering process and can thus be implemented in the same production process as the manufacturing of the tachometer itself.

[0049] The proposed damping structure 200 enables a significantly improved anti-interference field capability for the magnetic tachometer, thereby reducing or even eliminating the cost of the magnetic shielding layer required in use, especially in other situations.

[0050] Additionally, due to the limited lateral extension of the damping layer, the proposed solution achieves, as Figure 11 and 12 The angle sensor and tachometer shown, as well as the evaluation electronics as necessary, are also (as in...) Figure 3 As shown in the diagram, all components are integrated into a common, tightly sealed housing 213. Through this invention, the distance between the angle sensor 101 and the tachometer 102 is determined to be on the order of less than 500 μm. Commercially available chip housings can be used for the housing 213. This reduces the overall system cost, enabling a more compact solution and thus significant cost savings. A smaller permanent magnet 100 can also be used with this invention, further reducing the overall system cost. The wider magnetic window of the tachometer 102, achieved through this invention, also allows for lower tolerance requirements on the permanent magnet 100.

[0051] List of reference numerals

[0052] 100 permanent magnets

[0053] 101 Angle Sensor

[0054] 102 RPM meter

[0055] 103 Evaluate electronic components

[0056] 104 Chips with angle sensor and tachometer

[0057] 105 circuit board

[0058] 200 Damping Structure

[0059] 201 Soft magnetic conductor as a component of GMR or TMR stacks used to guide magnetic domains

[0060] 202 Metallization Department

[0061] 203 Insulating Interlayer

[0062] 204 silicon substrate

[0063] 205 Contact with contact opening

[0064] 206 The lower part of the chip (casing)

[0065] 207 welding wire

[0066] 208 Contact disk in chip housing

[0067] 209 Planarization Layer

[0068] The circle marked 210 (used later in...) Figure 9 and 10 (Description in the text)

[0069] 211 SMD pads

[0070] 212 Soft magnetic conductors as components of GMR or TMR angle sensors

[0071] 213 Outer shell

[0072] 401 Non-ferromagnetic thin layer

[0073] 402 Ferromagnetic Thin Film

[0074] 501 generates a layer with magnetic perpendicular anisotropy of layer 502.

[0075] 502 ferromagnetic thin film

[0076] 601 Non-magnetic matrix

[0077] 602 (super compliant) magnetic particles.

Claims

1. A magnetic system for counting revolutions with improved resistance to interference magnetic fields, comprising an angle sensor (101) for determining the field direction of a magnetic field of a permanent magnet (100) that is jointly covered by the angle sensor and the tachometer (102), wherein, The tachometer is composed of a known type of GMR or TMR tachometer, and the angle sensor (101) and the tachometer (102) are arranged side by side in a common housing (213) and / or on a common circuit board (105). The tachometer (102) is characterized by having a magnetically damping structure (200) that automatically adapts to its magnetic action, except for the portion made of a homogeneous soft magnetic material, which has no self-magnetic field or only a negligible self-magnetic field when the external magnetic field is zero.

2. The magnetic system according to claim 1, characterized in that, The damping structure (200) extends laterally beyond the soft magnetic GMR or TMR structure (201) of the tachometer (102) by no more than 30% as a damping layer.

3. The magnetic system according to claim 2, characterized in that, The damping layer is composed of a stack of layers consisting of stacked, planar, and correspondingly antiparallel ferromagnetic sublayers (402), the thickness of which is chosen such that the sublayers magnetically compensate each other, wherein the sublayers (402) are separated by non-ferromagnetic thin layers (401).

4. The magnetic system according to claim 2, characterized in that, The damping layer is composed of a stack of layers consisting of at least one ferromagnetic layer (502) which is covered on both sides by two non-ferromagnetic layers (501). The ferromagnetic layer (502) has a perpendicular magnetization parallel to the normal of the ferromagnetic layer (502), and adjacent magnetic field regions occupy an antiparallel direction.

5. The magnetic system according to claim 2, characterized in that, The damping layer is composed of a layer system comprising an assembly of small superparamagnetic particles (602), each superparamagnetic particle having its own superparamagnetic moment and being randomly oriented and embedded in a nonmagnetic matrix (601).

6. The magnetic system according to any one of claims 1 to 5, characterized in that, The damping structure (200) is disposed above or below the magnetically sensitive portion of the tachometer (102) which is a soft magnetic GMR or TMR structure (201).

7. The magnetic system according to any one of claims 1 to 5, characterized in that, The type of throttle meter (102) used in the damping structure (200) is given, which is also different from a circle in the top view, to take into account the effect of shape anisotropy.

8. The magnetic system according to claim 1, characterized in that, The distance between the angle sensor (101) and the tachometer (102) is determined to be on the order of less than 500 µm, and at least these two components are tightly sealed by a common housing (213).

9. The magnetic system according to claim 1, characterized in that, The distance between the angle sensor (101) and the tachometer (102) is determined to be on the order of less than 500 µm, and at least these two components, together with the evaluation electronics (103), are tightly sealed within a common housing (213).

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