Sensor and method for evaluating a sensor

Abstract

The invention relates to a sensor with two supply connections, four measuring paths, and two evaluation circuits, wherein the measuring paths comprise anisotropic magnetoresistive resistance elements and are connected in a total of four half-bridges, so that both a pole crossing and a direction of rotation can be detected and functional safety is ensured. The invention further relates to an associated method.

Description

[0001] The invention relates to a sensor and an associated method for evaluating a sensor

[0002] Sensors are used, for example, to determine the movement of a pole wheel or a linear element. A pole wheel can, for example, be used to measure the rotation of a wheel. The pole wheel is typically mounted so that it rotates at the same speed and in the same direction as the wheel. If the speed of rotation of the pole wheel or a signal indicating this and / or a direction of rotation is measured by a sensor, this provides information about the rotation of the wheel. This procedure can be used, for example, to determine the rotational speed and direction of a vehicle wheel. This can be used to determine the speed of a motor vehicle or the need for intervention by driving stability systems.

[0003] It is an object of the invention to provide a sensor that is alternative to or better than known designs. It is also an object of the invention to provide a corresponding method. This is achieved according to the invention by a sensor and a method according to the respective main claims. Advantageous embodiments can be found, for example, in the respective subclaims. The content of the claims is incorporated into the content of the description by express reference.

[0004] The invention relates to a sensor. The sensor has a first supply connection and a second supply connection. The sensor has a first measuring path with a first measuring connection. The sensor has a second measuring path with a second measuring connection. The sensor has a third measuring path with a third measuring connection. The sensor has a fourth measuring path with a fourth measuring connection. The sensor has a first evaluation circuit and a second evaluation circuit. All measuring paths are connected between the first supply connection and the second supply connection. Each measuring path has at least one upper resistance element that is connected between the first supply connection and the measuring connection. Each measuring path has at least one lower resistance element that is connected between the measuring connection and the second supply connection. The resistance elements are in particular anisotropic magnetoresistive.The magnetic orientations of the upper resistance elements are typically different from the magnetic orientations of the lower resistance elements of each measurement path. The second measurement path and the third measurement path are arranged between the first measurement path and the fourth measurement path, as viewed along an x-axis of the sensor. The resistance elements extend, in particular, along a y-axis of the sensor. The first evaluation circuit is connected to the first measurement terminal and the fourth measurement terminal. The second evaluation circuit is connected to the second measurement terminal and the third measurement terminal.

[0005] Such a sensor can advantageously detect the movement of a magnet wheel, whereby both the rotational speed and the direction of rotation can be detected. The claimed embodiment has proven to be particularly robust. The two evaluation circuits can be used in an advantageous manner, in particular, such that one of them, in particular the first evaluation circuit, is used to determine the direction of rotation, and the other evaluation circuit is used to determine the rotational speed. It is also possible to compare the data obtained from both evaluation circuits.

[0006] A sensor is understood here in particular to be a sensor that is capable of detecting the movement of a magnet wheel. A magnet wheel is basically a wheel that has a sequence of magnets with different polarities, so that a structured magnetic field is generated in the environment, which can be detected in particular by the sensor. The magnet wheel typically moves along the x-axis mentioned above. Instead of a magnet wheel, a linear element can also be used. This typically also has a sequence of magnets with different polarities. A magnet wheel can also be designed in a gear-shaped configuration. In particular, protruding teeth can be present, which in particular differently deflect the field lines of a permanent magnet attached to the sensor. Such a structure with protruding teeth is also possible with a linear element.

[0007] A supply connection is understood, in particular, to be a connection for a current or voltage supply to the sensor. In particular, the second supply connection can be a ground connection. The first supply connection can, in particular, be a connection for a positive or negative supply voltage. The first supply connection can also be split in two, so that different measuring paths can be supplied with different supply voltages, for example, to implement a functionality in which only some of the measuring paths are actually used and the others are not supplied with a supply voltage, thus deactivating them. This will be discussed in more detail below.

[0008] A measuring path is typically understood to be a current path that, as mentioned, extends between the two supply terminals and has at least one upper resistance element and at least one lower resistance element, between which a measuring terminal is arranged. The measuring terminal does not necessarily have to be directly visible on the sensor; rather, it is a location along a conductor at which a voltage can be tapped. There can also be any number of such locations between two resistance elements. For example, a connection pad can be provided for a measuring terminal.

[0009] The evaluation circuits are typically designed to generate an output from the two input variables. In particular, this can be a differential amplifier or operational amplifier. In particular, an output signal in the form of a voltage or current can be generated from the difference between the voltages at two measuring terminals. This output signal can then be further processed in an appropriate manner.

[0010] The terms "upper resistance element" and "lower resistance element" serve merely to linguistically differentiate between the two different resistance elements. They refer to a typical design in which, when viewed from above on a vertically oriented paper plane, the upper resistance elements are arranged above the lower resistance elements, at least when the respective measuring path does not have a bend. Depending on the spatial orientation of a sensor, however, any spatial orientation of the upper resistance elements and lower resistance elements can exist. An anisotropic magnetoresistive material, in particular, has a specific magnetic orientation. If an external magnetic field is applied parallel to this magnetic orientation, the anisotropic magnetoresistive material has a particularly low or a particularly high resistance.If the external magnetic field is perpendicular to the magnetic orientation, the electrical resistance changes significantly compared to an external magnetic field orientation parallel to the magnetic orientation. This can be used to detect a magnetic field. By using resistance elements with different magnetic orientations, the effect of an externally applied magnetic field can be detected particularly effectively. For example, a certain external magnetic field can cause an upper resistance element to decrease its resistance while a lower resistance element simultaneously increases its resistance. This amplifies the effect and makes the measured signal more distinct.

[0011] The x-axis is an axis that can be suitably defined for a sensor. For example, in a plan view of the sensor with a vertical paper plane, it can extend horizontally. The y-axis typically extends transversely to the x-axis, preferably exactly perpendicular to it. In a plan view of the sensor with a vertical paper plane, it can typically extend vertically upwards. The x- and y-axes serve here merely to linguistically capture the geometric relationships in the sensor. They are typically not shown in a sensor and can be suitably defined to check whether a sensor falls under the claimed embodiment. The x-axis also defines an x-direction, and the y-axis also defines a y-direction.

[0012] In particular, it can be provided that the second measuring path and the third measuring path cross at a respective point between the upper resistance element and the lower resistance element. This can be understood in particular in electrical and / or geometric terms. In particular, the current flow crosses along the x-axis, although this does not necessarily mean that two conductor tracks overlap at a point. As will be described in more detail below, this can also mean that a suitable cable routing is selected which achieves a crossing of the current flow even without a crossing point between conductor tracks. By crossing the measuring paths, the influence of acting magnetic fields on the second and third measuring paths is evened out. In particular, the extent to which an acting magnetic field covers the second measuring path or the third measuring path should be as little relevant as possible or irrelevant.The influence should be as independent as possible from the exact location.

[0013] In particular, it can be provided that the upper resistance element of the second measuring path has a magnetic orientation which is different from the magnetic orientation of the upper resistance element of the third measuring path and / or is oriented transversely thereto. In particular, it can be provided that the lower resistance element of the second measuring path has a magnetic orientation which is different from the magnetic orientation of the lower resistance element of the third measuring path and / or is oriented transversely thereto. This can in particular achieve that the effect of a magnetic field acting on the second and third measuring paths is reversed in the measuring paths and thus a voltage difference between the second measuring connection and the third measuring connection is increased. This can improve the signal quality.

[0014] In particular, the upper resistance element of the second measuring path and the lower resistance element of the third measuring path can be arranged along a common line, or along a common line parallel to the y-axis. In particular, the upper resistance element of the third measuring path and the lower resistance element of the second measuring path can be arranged along a common line, or along a common line parallel to the y-axis. Such arrangements achieve a crossing of the measuring paths. A magnetic component parallel to the y-axis can reach resistance elements of both the second measuring path and the third measuring path. In particular, such an embodiment can be understood as a crossing of the two measuring paths. In particular, the resistance elements can extend along a respective longitudinal direction, whereby they are typically longer along this longitudinal direction than transverse to this longitudinal direction.In particular, resistance elements can be designed as flat components, for example, with rectangular components on the outer periphery. Accordingly, a longitudinal axis can be defined along a direction along which the resistance element has its greatest extent parallel to the side edges. In particular, a resistance element can be considered a two-dimensional structure.

[0015] The arrangement of two resistance elements along a common axis can, in particular, mean that they have the same extension when viewed transversely to the axis. In particular, the outer edges of the two resistance elements can thus also lie on a common axis.

[0016] According to one embodiment, the first measuring path can have a first upper resistance element and a second upper resistance element connected in series therewith. According to one embodiment, the first measuring path can have a first lower resistance element and a second lower resistance element connected in series therewith. According to one embodiment, the fourth measuring path can have a first upper resistance element and a second upper resistance element connected in series therewith. According to one embodiment, the fourth measuring path can have a first lower resistance element and a second lower resistance element connected in series therewith. In particular, the two resistance elements just mentioned can each be connected together like a single resistance element to other components.By using two resistance elements, a gap can be created between the resistance elements, allowing for higher resolution compared to using only one resistance element. Furthermore, an advantageous geometric arrangement is possible when using two resistance elements as described above, which will be discussed in more detail below.

[0017] In particular, the first upper resistance element and the second upper resistance element of the first measuring path can be arranged along a common line, or along a common line parallel to the y-axis. In particular, the first lower resistance element and the second lower resistance element of the first measuring path can be arranged along a common line, or along a common line parallel to the y-axis. In particular, the first upper resistance element and the second upper resistance element of the fourth measuring path can be arranged along a common line, or along a common line parallel to the y-axis. In particular, the first lower resistance element and the second lower resistance element of the fourth measuring path can be arranged along a common line, or along a common line parallel to the y-axis.This allows for a simple design, which has proven to be advantageous in terms of sensitivity.

[0018] In particular, the first upper resistance element of the first measuring path, the first lower resistance element of the first measuring path, the upper resistance element of the second measuring path, the upper resistance element of the third measuring path, the first upper resistance element of the fourth measuring path, and the first lower resistance element of the fourth measuring path can be arranged on a line or on a line parallel to the x-axis. In particular, the second upper resistance element of the first measuring path, the second lower resistance element of the first measuring path, the lower resistance element of the third measuring path, the lower resistance element of the second measuring path, the second upper resistance element of the fourth measuring path, and the second lower resistance element of the fourth measuring path can be arranged on a line or on a line parallel to the x-axis. Reference is made to the above-mentioned explanations regarding the y-axis.In contrast to the y-axis, however, the resistance elements typically extend along the x-axis by a shorter amount, wherein in an arrangement on a line as described herein, short sides of the resistance elements, which are formed, for example, as a rectangle, are typically aligned parallel to the x-axis.

[0019] In particular, the sensor can have a center point or a center line. A center line can, for example, be perpendicular to the x-axis and / or parallel to the y-axis. A center point can, for example, be located on the center line. The center line can, in particular, have the following properties and / or be defined by them.

[0020] It can be provided that the second measuring path has the same distance from the center point or center line along the x-axis as the third measuring path. It can be provided that the first measuring path has the same distance from the center point or center line along the x-axis as the fourth measuring path. This allows a symmetrical arrangement relative to the center point or center line to be achieved. In particular, it can be provided that the second measuring path and the third measuring path are arranged closer to each other than the first measuring path and the fourth measuring path.

[0021] In particular, it can be provided that the second measuring path and the third measuring path are arranged within a range of at most 300 µm or at most 400 µm along the x-axis. Such small distances have proven advantageous in that the exact position of a magnetic field line intersecting at least one of the measuring paths is irrelevant, so that the effect of the magnetic field on the second and third measuring paths is largely identical.

[0022] In particular, the first measuring path and the second measuring path can be spaced apart along the x-axis by at least 500 µm and / or by at most 700 µm. In particular, the third measuring path and the fourth measuring path can be spaced apart along the x-axis by at least 500 µm and / or by at most 700 µm. Such spacings have proven advantageous. However, depending on the pole wheels used, other spacings can also be used.

[0023] Distances can be measured, for example, between the center points of measurement paths or between the entire outer boundaries of the respective measurement paths. This prevents the measurement paths from interfering with each other or from magnetic field lines influencing too many measurement paths simultaneously.

[0024] In particular, a magnetic orientation of some or all of the upper resistance elements may be orthogonal to a magnetic orientation of some or all of the lower resistance elements of the same measurement path. This may, for example, refer to the respective resistance elements of a measurement path under consideration. It may also refer to further, and in particular, to all of the resistance elements under consideration.

[0025] In particular, it can be provided that the magnetic orientations of some or all resistance elements form an angle of at least 40° and / or of at most 50°, or of 45°, to the y-axis. This allows a uniform arrangement of the magnetic orientations of the resistance elements in question.

[0026] In particular, some or all of the resistance elements can be elongated. A respective central axis can extend, in particular, along the y-axis. An elongated design can be understood, in particular, as a rectangular design, wherein two opposite edges are significantly longer than the other two edges. In particular, these can be at least 10%, at least 200%, at least 300%, at least 500%, or at least 1,000% longer than the other edges. A central axis can, in particular, be an axis of symmetry of the respective resistance element.

[0027] According to an advantageous embodiment, the first supply connection can be divided into a first section and a second section. The first section can in particular be switchable independently of the second section. In particular, it can be provided that the first measuring path and the fourth measuring path are connected to the first section. In particular, it can be provided that the second measuring path and the third measuring path are connected to the second section. As a result, those measuring paths responsible for detecting a rotation can be switched independently of those measuring paths responsible for detecting a direction of rotation. As a result, energy can be saved, for example, by selective switching off. This will be discussed in more detail below with reference to the method described herein.

[0028] In particular, it can be provided that in the second measuring path and / or the third measuring path, the upper resistance elements have a top connection in the y-direction, to which a connection is connected which is connected to a top connection of the lower resistance element in the y-direction, wherein the measuring connection is located in the connection. The concept of a bottom and / or top connection is seen in the y-direction, whereby a zero point can be defined from which the y-direction extends along the y-axis. For example, in a top view of the sensor and a vertical paper plane, the y-direction can point vertically upwards. Accordingly, the concept of a bottom or top connection can be clearly assigned, even if the sensor can have a different orientation in space. It is sufficient that the described configuration exists in at least one possible orientation.Such a design advantageously allows for a crossover between the second and third measurement paths without the need for an actual physical crossing of conductor tracks. This avoids the need to create a crossover using an additional conductive layer.

[0029] In particular, it can be provided that in the second measuring path and / or the third measuring path, the upper resistance elements in the y-direction have a bottom connection connected to a supply connection. In particular, it can be provided that in the second measuring path and / or the third measuring path, the lower resistance elements in the y-direction have a bottom connection connected to a supply connection. This also allows for an advantageous design of a connection of these resistance elements when the measuring paths cross, without the need for an additional plane.

[0030] In particular, the x-axis can be orthogonal or perpendicular to the y-axis. This can, in particular, mean an angle of 90°. However, slight deviations from this, for example, ± 1°, 2°, or 5°, can also be used.

[0031] In particular, the first evaluation circuit can be a differential amplifier. In particular, the second evaluation circuit can be a differential amplifier. Such a differential amplifier can, in particular, generate an output signal such as a voltage or a current that is dependent on, for example, proportional to, a difference between two input-side voltage signals. These input-side voltage signals are the voltages at the respective connected measuring terminals. This allows for direct evaluation of the output signals with regard to the speed of rotation about the direction of rotation.

[0032] In particular, it is advantageous if the resistance elements occupy the entire space, or at least largely the entire space, viewed in the y-direction. In particular, they can occupy the entire extent of the magnet wheel in the y-direction, or at least largely the entire extent, for example, at least 90%.

[0033] In particular, a sensor as described herein may include a supporting magnet that generates a supporting magnetic field. This is typically superimposed on the magnetic field generated by a pole wheel or other unit to be measured.

[0034] The invention further relates to a method for evaluating a sensor, in particular a sensor as described herein. The method comprises the following steps: - reading out a first output signal of the first evaluation circuit and / or a second output signal of the second evaluation circuit, - Detecting a zero crossing in one of the output signals, and - in response to this, detection of a pole passage.

[0035] Such a method allows for advantageous evaluation of a sensor to determine the movement of a neighboring pole wheel. A pole passage can, in particular, mean that one or two poles have passed the sensor. Poles typically alternate on a pole wheel such that one pole always follows an inversely magnetized pole. Typically, only two types of poles are present on a pole wheel. Regarding the sensor used, all embodiments and variants described herein can be used.

[0036] In particular, a pole crossing can be determined independently of the direction of rotation using the first output signal. The second output signal, or its amplitude and / or sign, especially at the same time, can then be used to determine the direction of rotation. However, the reverse procedure is also possible. A zero crossing in one of the output signals typically indicates that the pole wheel has rotated further by a certain angular amount, and therefore the sign of one of the output signals has changed.

[0037] It should be understood that a corresponding procedure using a possibly existing offset, so that no zero crossing but rather a passing of a specific value, in particular an average value of a signal that is different from zero, is detected, is considered equivalent. The offset or average value can, for example, be calculated from upper and lower limits of the signal, for example as the arithmetic mean between these two values. The upper and lower limits can, for example, limit an actually measured signal, or they can limit a range of values. The offset or average value can also be determined from an area integral of the measured signal.

[0038] In particular, it can be provided that, at the zero crossing of one output signal, a direction of rotation is detected based on the sign of the other output signal. The sign of the other output signal thus serves to determine the direction of rotation, while a zero crossing serves to detect a pole crossing. In principle, this can be implemented by using the first output signal to detect the sign and the second output signal to detect the zero crossing, or vice versa.

[0039] In particular, it can be provided that in response to an error condition or a request, a supply to the first measuring path and the fourth measuring path is switched off, or a supply to the second measuring path and the third measuring path is switched off. This creates an opportunity to save energy because, for example, when a vehicle is in normal operation while driving forward, the direction of rotation typically does not change for a long period of time and therefore does not have to be detected again and again. Two measuring paths can therefore be switched off without any relevant information being lost. Such a request can, for example, come from a vehicle control system which detects that the vehicle is in normal operation while driving forward. An error condition can be detected by different units of a motor vehicle.For example, an inconsistency in the generated output data or output signals can be detected. In this case, some of the measurement paths can be disabled, especially those paths where malfunction is expected. This can significantly increase functional safety, since even if an error occurs in one or two measurement paths, the sensor's functionality is still possible.

[0040] In particular, zero crossings of both output signals can be determined. Pole crossings determined using the first output signal and pole crossings determined using the second output signal can be compared against each other. This can mean, for example, that an error is detected if pole crossings detected with different output signals are separated by more than an absolute or relative threshold, or if their repetition rates differ by more than an absolute or relative threshold.

[0041] If three zero crossings of an output signal are detected within a predetermined period of time, a common zero crossing can be formed from these three zero crossings before further processing steps. This can ensure that, in the event that a certain fluctuation in the output signal leads not only to a zero crossing but to three consecutive zero crossings, these are processed correctly. Such a triplet of zero crossings can mean, in particular, that the magnetic excitation field is too strong or that the pole spacing of the pole wheel is too large relative to the dimensions of the sensor. By using a common zero crossing as described herein, further evaluation can advantageously be carried out even in such situations, just as if only one zero point had been detected from the outset.

[0042] Disabling measurement paths can be achieved, in particular, by implementing the sensor with two sections of the first measurement path as described above. Alternatively, the second measurement path can also be divided into two sections.

[0043] According to one embodiment, a zero crossing can be detected when an output signal crosses a predetermined value, or an average value of the signal. The predetermined value can, for example, be permanently stored, in particular, permanently stored for a longer period of time.

[0044] The mean can be, for example, - upper and lower limits of the signal, - from upper and lower maximum values ​​of the signal, and / or - as the effective value of the signal. is determined.

[0045] Upper and lower limits of the signal typically delimit the range of values ​​that the signal actually occupies over a certain period of time. Upper and lower maximum values ​​typically delimit the range that the signal can, in principle, occupy. An RMS value can be determined, for example, from an area integral of the signal over a given period of time.

[0046] The invention further relates to a control device configured to carry out a method as described herein. The invention further relates to a sensor having such a control device. The invention further relates to a non-volatile computer-readable storage medium on which program code is stored, the execution of which causes a processor to carry out a method described herein. With regard to the method described herein, all embodiments and variants described herein may be used.

[0047] The invention further relates to a sensor arrangement comprising a sensor as described herein and a magnet wheel or a linear element with multiple magnetic poles. The sensor can, in particular, be arranged relative to the magnet wheel or the linear element in such a way that it can sense a movement of the magnet wheel or the linear element. With regard to the sensor, all embodiments and variants described herein can be used.

[0048] In particular, the configuration described here is based on a total of four half-bridges. These have different spatial arrangements around a center point. Each measurement path typically contains resistor elements of different types, so that the respective signal is amplified.

[0049] An identical, or at least largely identical, distance between the first measurement path and the fourth measurement path from the center point, as described above as an advantageous embodiment, can, in particular, lead to a very reliable zero crossing of the resulting output signal. The output signal is typically free of any offset, but could also be processed with an offset. Such an offset can occur, for example, when using strong magnetic fields.

[0050] The design described herein enables, in particular, particularly good functional safety. The signal typically used to detect a direction of rotation can also be used for pulse detection or qualification. In this case, the other signal, which is otherwise used for pulse detection, can be used to detect a direction of rotation. This allows for functional cross-checking. During a fault condition, for example, the power consumption can be reduced, e.g., to signal the fault condition. In particular, this can be achieved, as described above, by deactivating two of the measuring paths. Nevertheless, the functionality for detecting pole crossings remains.

[0051] In particular, an interference field can be detected based on the fact that an average value of the second output signal deviates from the zero point by at least a specified value. This can, for example, be forwarded as an error message to other components and / or used as an error condition to control the sensor. The average can, for example, be calculated over a specified number of measured values ​​or over a specified period of time.

[0052] In particular, if three zero crossings are detected in the first output signal within a specified period, an error condition can be detected, particularly regarding an excessively strong excitation magnetic field and / or an excessively large pole spacing. Such an error condition is also referred to as a triplet. It indicates the aforementioned causes of the error. It can, for example, be forwarded to other components as an error message and / or used as an error condition to control the sensor.

[0053] Further features and advantages will become apparent to those skilled in the art from the exemplary embodiments described below with reference to the accompanying drawings. These show: Fig. 1: a sensor according to a first embodiment, Fig. 2: a sensor according to a second embodiment, and Fig. 3: a curve of output signals.

[0054] Fig. Figure 1 shows a purely schematic diagram of a sensor 50 according to a first embodiment of the invention. The sensor 50 has a first supply terminal Vcc and a second supply terminal Vss. The second supply terminal Vss is a ground terminal in this case. The first supply terminal Vcc provides a supply voltage that is positive or negative relative to ground.

[0055] The sensor 50 has a first measuring path 100, a second measuring path 200, a third measuring path 300, and a fourth measuring path 400. As shown, the measuring paths 100, 200, 300, and 400 are each connected between the two supply terminals Vcc and Vss. This allows them to be suitably supplied with the required operating voltage.

[0056] An x-axis and a y-axis are defined in the sensor 50. These are shown in the bottom left corner using a coordinate system. The x-axis is the horizontal direction in the plane of the paper from Fig. 1. The y-axis is the vertical direction in the plane of the paper from Fig. 1. The two axes are perpendicular to each other. A pole wheel or a linear element (not shown) typically moves in the x-direction.

[0057] As shown, the second measuring path 200 and the third measuring path 300 are arranged between the first measuring path 100 and the fourth measuring path 400 along the x-axis.

[0058] The measurement paths 100, 200, 300, and 400 have multiple resistance elements. These are described below. As shown, the resistance elements are rectangular in plan view. The longer sides are all parallel to one another. The shorter sides are also all parallel to one another. The shorter sides extend along the x-axis. The longer sides extend along the y-axis. The resistance elements are made of an anisotropic magnetoresistive material. Each such anisotropic magnetoresistive material has a magnetic orientation. These are shown next to the respective resistance elements. Some of the magnetic orientations are at a 45° angle to the y-axis with a gradient from bottom left to top right, and some magnetic orientations are arranged at a 45° angle to the y-axis with a gradient from top left to bottom right.The magnetic orientations shown in the figures represent preferred embodiments. Each measurement path generally has 100, 200, 300, or 400 resistance elements with both magnetic orientations. These are generally connected in series, thus enhancing the anisotropic magnetoresistive effect.

[0059] The first measuring path 100 has a first measuring connection 130. The second measuring path 200 has a second measuring connection 230. The third measuring path 300 has a third measuring connection 330. The fourth measuring path 400 has a fourth measuring connection 430. Those resistance elements that are connected between the first supply connection Vcc and the respective measuring connection 130, 230, 330, 430 are referred to as upper resistance elements. Those resistance elements that are connected between the respective measuring connection 130, 230, 330, 430 and the second supply connection Vss are referred to as lower resistance elements. This serves only as a linguistic distinction and basically refers to the geometric or circuit arrangement in Fig. 1. However, this does not say anything about the actual orientation in the sensor 50 for any orientation of the sensor 50 in space, since the sensor 50 can in principle be oriented in any way in space.

[0060] The first measuring path 100 has a first upper resistance element 111 and a second upper resistance element 112. It further has a first lower resistance element 121 and a second lower resistance element 122. Correspondingly, the fourth measuring path 400 has a first upper resistance element 411, a second upper resistance element 412, a first lower resistance element 421, and a second lower resistance element 422. Thus, two lower and two upper resistance elements are present, so that the overall effect can be amplified. Furthermore, this allows for more uniform sensing along the y-axis, i.e., the degree of distribution of the effect of an acting magnetic field along the y-axis is less important.

[0061] The second measuring path 200 has an upper resistance element 210 and a lower resistance element 220. The third measuring path 300 has an upper resistance element 310 and a lower resistance element 320. The two upper resistance elements 210, 310 are mirror images of each other in terms of their magnetic orientation. The same applies to the two lower resistance elements 320, 220. The second and third measuring paths 200, 300 are crossed as shown, so that the lower resistance element 320 of the third measuring path 300 is located below the upper resistance element 210 of the second measuring path 200 in the y-direction, and the lower resistance element 220 of the second measuring path 200 is located below the upper resistance element 310 of the third measuring path 300 in the y-direction.

[0062] As shown, the first upper resistance element 111 of the first measuring path 100, the first lower resistance element 121 of the first measuring path 100, the upper resistance element 210 of the second measuring path 200, the upper resistance element 310 of the third measuring path 300, the first upper resistance element 411 of the fourth measuring path 400, and the first lower resistance element 421 of the fourth measuring path 400 are arranged at the same height. This applies in this case to both the upper short edges and the lower short edges of the respective resistance elements mentioned. The same applies to the other resistance elements, i.e.the second upper resistance element 112 of the first measuring path 100, the second lower resistance element 122 of the first measuring path 100, the lower resistance element 320 of the third measuring path 300, the lower resistance element 220 of the second measuring path 200, the second upper resistance element 412 of the fourth measuring path 400, and the second lower resistance element 422 of the fourth measuring path 400.

[0063] The two second and third measuring paths 200, 300 should be as close to each other as possible. A center line 60 is drawn as a reference, from which the two second and third measuring paths 200, 300 have distances a2, a3 of approximately 130 µm each. The first and fourth measuring paths 100, 400 have distances a1, a4 of approximately 660 µm from the second measuring path 200 and the third measuring path 300, respectively. Such dimensions have proven advantageous for typical applications. As shown, the specified distances refer to the center point of the respective measuring path 100, 200, 300, 400 in the x-direction.

[0064] The sensor 50 has a first evaluation circuit AW1 and a second evaluation circuit AW2. These are embodied as differential amplifiers. They each have a positive input (+) and a negative input (-). Their respective output signals indicate the difference between the two input signals. As shown, the first evaluation circuit AW1 is connected to the first measuring terminal 130 and the fourth measuring terminal 430. As a result, the output signal of the first evaluation circuit AW1 is proportional to a difference between the voltages at these two measuring terminals 130, 430. The two outer measuring paths, i.e., the first measuring path 100 and the fourth measuring path 400, can be used to detect the direction of rotation of a magnet wheel moving near the sensor 50, typically in the x-direction.

[0065] The second evaluation circuit AW2 is connected to the second measuring terminal 230 and the third measuring terminal 330. This determines a difference between the voltages at these two measuring terminals 230, 330, which can be further evaluated. A zero crossing of the output signal typically indicates that a pole crossing of the magnet wheel has occurred.

[0066] Fig. Figure 2 shows a sensor 50 according to a second embodiment. The arrangement of the resistance elements is identical to the design of Fig. 1. The wiring, however, is different. In particular, pads are provided for the measuring terminals 130, 230, 330, and 430. These can be contacted using bonding wires. A pad is also provided for the second supply terminal Vss. In contrast to the design of Fig. 1, the first supply connection Vcc is split in two. A first section Vcc1 is provided, which supplies the first measuring path 100 and the fourth measuring path 400. Furthermore, a second section Vcc2 is provided, which supplies the second measuring path 200 and the third measuring path 300. The two sections Vcc1, Vcc2 are not electrically connected to one another in this case. However, a gap is provided at a separation point 70, which would in principle be suitable for connecting the two sections Vcc1, Vcc2 to one another by continuing the electrical connection. The two sections Vcc1, Vcc2 of the first supply connection Vcc also have respective pads for bonding.

[0067] As shown, the wiring is arranged such that the two resistance elements 220, 320 of the second and third measuring paths 200, 300, arranged at the bottom in the y-direction, are contacted from above, with a connection being made to a respective upper side of the other resistance element 210, 310. Such a wiring makes it possible to provide the aforementioned electrical crossover without requiring an additional wiring level. This significantly simplifies the manufacture of the sensor.

[0068] As in Fig. As can be seen in Figure 2, the pad for the second supply connection Vss is located in the center in the x-direction. This achieves a symmetrical ground connection.

[0069] Fig. Figure 3 shows the output signal curve of the evaluation circuits AW1, AW2. These are generally sinusoidal, which is an ideal shape. The basic evaluation procedure is to determine a zero crossing, possibly in the form of a common zero crossing, of the output signal of the second evaluation circuit AW2. This indicates that a pole crossing has occurred, i.e. that the magnet wheel has rotated further by a certain angle. Based on the sign of the output signal of the first evaluation circuit AW1 at this point, the direction of rotation can then be deduced. Depending on whether the sign is negative or positive at this point, the magnet wheel rotates in one direction or the other.

[0070] Alternatively, a zero crossing, possibly in the form of a common zero crossing, could be determined in the output signal of the first evaluation circuit AW1, and the direction of rotation could be determined based on the sign of the output signal of the second evaluation circuit AW2.

[0071] If an error occurs or if energy needs to be saved, this can be particularly helpful when executing Fig.2 a portion of the measuring paths can be switched off, for example to signal an error condition. For example, the first measuring path 100 and the fourth measuring path 400 can be switched off by connecting the first section Vcc1 of the first supply connection Vcc to ground. In this case, only the second measuring path 200 and the third measuring path 300 are still in operation. A pole passage of a magnet wheel can still be determined based on a zero crossing of the determined output signal. Although the direction of rotation can no longer be determined in this case, this is typically no longer necessary if a vehicle only travels forwards during normal operation. Before reversing, the vehicle would first have to come to a standstill, which can be detected, after which, for example, the sensor 50 can be put back into operation with all measuring paths 100, 200, 300, 400.

[0072] For further functional safety requirements, for example, it can detect the presence of a strong, homogeneous magnetic offset. Furthermore, it can detect that the magnetic excitation signal is too strong, or that the pole pitch of the magnet wheel is too large.

[0073] The steps mentioned in the method according to the invention can be carried out in the specified order. However, they can also be carried out in a different order, as long as this is technically reasonable. The method according to the invention can be carried out in one of its embodiments, for example, with a specific combination of steps, in such a way that no further steps are carried out. However, in principle, further steps can also be carried out, even those not mentioned.

[0074] It should be noted that features may be described in combination in the claims and the description, for example, to facilitate understanding, although they may also be used separately. Those skilled in the art will recognize that such features may also be combined independently with other features or combinations of features.

[0075] References in subclaims may indicate preferred combinations of the respective features, but do not exclude other combinations of features. List of reference symbols 50 sensors 60 center line 70 Separation point 100 first measuring path 111 first upper resistance element 112 second upper resistance element 121 first lower resistance element 122 second lower resistance element 130 first measuring connection 200 second measuring path 210 upper resistance element 220 lower resistance element 230 second measuring connection 300 third measuring path 310 upper resistance element 320 lower resistance element 330 third measuring connection 400 fourth measuring path 411 first upper resistance element 412 second upper resistance element 421 first lower resistance element 422 second lower resistance element Vcc first supply connection Vcc1 first section Vcc2 second section Vss second supply connection AW1 first evaluation circuit AW2 second evaluation circuit a distance

Claims

[1] Sensor (50), comprising - a first supply connection (Vcc), - a second supply connection (Vss), - a first measuring path (100) with a first measuring connection (130), - a second measuring path (200) with a second measuring connection (230), - a third measuring path (300) with a third measuring connection (330), - a fourth measuring path (400) with a fourth measuring connection (430), - a first evaluation circuit (AW1), and - a second evaluation circuit (AW2), - wherein all measuring paths (100, 200, 300, 400) are connected between the first supply terminal (Vcc) and the second supply terminal (Vss), - wherein each measuring path (100, 200, 300, 400) has at least one upper resistance element (111, 112, 210, 310, 411, 412) connected between the first supply terminal (Vcc) and the measuring terminal (130, 230, 330, 430), - wherein each measuring path (100, 200, 300, 400) has at least one lower resistance element (121, 122, 220, 320, 421, 422) connected between the measuring terminal (130, 230, 330, 430) and the second supply terminal (Vss), - wherein the resistance elements (111, 112, 121, 122, 210, 220, 310, 320, 411, 412, 421, 422) are anisotropic magnetoresistive, - wherein magnetic orientations of the upper resistance elements (111, 112, 210, 310, 411, 412) are different from the magnetic orientations of the lower resistance elements (121, 122, 220, 320, 421, 422) of each measuring path (100, 200, 300, 400), - wherein the second measuring path (200) and the third measuring path (300) are arranged between the first measuring path (100) and the fourth measuring path (400) as seen along an x-axis of the sensor (50), - wherein the resistance elements (111, 112, 121, 122, 210, 220, 310, 320, 411, 412, 421, 422) extend along a y-axis of the sensor (50), - wherein the first evaluation circuit (AW1) is connected to the first measuring terminal (130) and the fourth measuring terminal (430), and - wherein the second evaluation circuit (AW2) is connected to the second measuring terminal (230) and the third measuring terminal (330). [2] Sensor (50) according to claim 1, - wherein the second measuring path (200) and the third measuring path (300) cross at a respective point between the upper resistance element (210, 310) and the lower resistance element (220, 320). [3] Sensor (50) according to one of the preceding claims, - wherein the upper resistance element (210) of the second measuring path (200) has a magnetic orientation which is different from the magnetic orientation of the upper resistance element (310) of the third measuring path (300) and / or is oriented transversely thereto, and / or - wherein the lower resistance element (220) of the second measuring path (200) has a magnetic orientation which is different from the magnetic orientation of the lower resistance element (320) of the third measuring path (300) and / or is oriented transversely thereto [4] Sensor (50) according to one of the preceding claims, - wherein the upper resistance element (210) of the second measuring path (200) and the lower resistance element (320) of the third measuring path (300) are arranged along a common line, or along a common line parallel to the y-axis, and / or - wherein the upper resistance element (310) of the third measuring path (300) and the lower resistance element (220) of the second measuring path (200) are arranged along a common line, or along a common line parallel to the y-axis. [5] Sensor (50) according to one of the preceding claims, - wherein the first measuring path (100) comprises a first upper resistance element (111) and a second upper resistance element (112) connected in series therewith, and / or - wherein the first measuring path (100) comprises a first lower resistance element (121) and a second lower resistance element (122) connected in series therewith, and / or - wherein the fourth measuring path (400) comprises a first upper resistance element (411) and a second upper resistance element (412) connected in series therewith, and / or - wherein the fourth measuring path (400) comprises a first lower resistance element (421) and a second lower resistance element (422) connected in series therewith. [6] Sensor (50) according to claim 5, - wherein the first upper resistance element (111) and the second upper resistance element (112) of the first measuring path (100) are arranged along a common line, or along a common line parallel to the y-axis, and / or - wherein the first lower resistance element (121) and the second lower resistance element (122) of the first measuring path (100) are arranged along a common line, or along a common line parallel to the y-axis, and / or - wherein the first upper resistance element (411) and the second upper resistance element (412) of the fourth measuring path (400) are arranged along a common line, or along a common line parallel to the y-axis, and / or - wherein the first lower resistance element (421) and the second lower resistance element (422) of the fourth measuring path (400) are arranged along a common line, or along a common line parallel to the y-axis. [7] Sensor (50) according to one of claims 5 to 6, - wherein the first upper resistance element (111) of the first measuring path (100), the first lower resistance element (121) of the first measuring path (100), the upper resistance element (210) of the second measuring path (200), the upper resistance element (310) of the third measuring path (300), the first upper resistance element (411) of the fourth measuring path (400) and the first lower resistance element (421) of the fourth measuring path (400) are arranged on a line, or on a line parallel to the x-axis, and / or - wherein the second upper resistance element (112) of the first measuring path (100), the second lower resistance element (122) of the first measuring path (100), the lower resistance element (320) of the third measuring path (300), the lower resistance element (220) of the second measuring path (200), the second upper resistance element (412) of the fourth measuring path (400) and the second lower resistance element (422) of the fourth measuring path (400) are arranged on a line, or on a line parallel to the x-axis. [8] Sensor (50) according to one of the preceding claims, - wherein the sensor (50) has a center point or a center line (60), - wherein along the x-axis the second measuring path (200) has the same distance from the center or center line (60) as the third measuring path (300), and / or - wherein along the x-axis the first measuring path (100) has the same distance from the center or center line (60) as the fourth measuring path (400). [9] Sensor (50) according to one of the preceding claims, - wherein the second measuring path (200) and the third measuring path (300) are arranged within a range of at most 300 µm or at most 400 µm along the x-axis. [10] Sensor (50) according to one of the preceding claims, - wherein the first measuring path (100) and the second measuring path (200) have a distance along the x-axis of at least 500 µm and / or of at most 700 µm from each other, and / or - wherein the third measuring path (300) and the fourth measuring path (400) have a distance along the x-axis of at least 500 µm and / or of at most 700 µm from each other. [11] Sensor (50) according to one of the preceding claims, - wherein a magnetic orientation of some or all of the upper resistance elements (111, 112, 210, 310, 411, 412) is orthogonal to a magnetic orientation of some or all of the lower resistance elements (121, 122, 220, 320, 421, 422) of the same measuring path (100, 200, 300, 400). [12] Sensor (50) according to one of the preceding claims, - wherein the magnetic orientations of some or all of the resistance elements (111, 112, 121, 122, 210, 220, 310, 320, 411, 412, 421, 422) form an angle of at least 40° and / or of at most 50°, or of 45°, to the y-axis. [13] Sensor (50) according to one of the preceding claims, - wherein some or all of the resistance elements (111, 112, 121, 122, 210, 220, 310, 320, 411, 412, 421, 422) are elongated and a respective central axis extends along the y-axis. [14] Sensor (50) according to one of the preceding claims, - wherein the first supply terminal (Vcc) is divided into a first section (Vcc1) and a second section (Vcc2), - wherein the first section (Vcc1) is switchable independently of the second section (Vcc2), - wherein the first measuring path (100) and the fourth measuring path (400) are connected to the first section (Vcc1), and - wherein the second measuring path (200) and the third measuring path (300) are connected to the second section (Vcc2). [15] Sensor (50) according to one of the preceding claims, - wherein in the second measuring path (200) and / or in the third measuring path (300), the upper resistance elements (210, 310) have a top terminal in the y-direction, to which a connection is connected which is connected to a top terminal in the y-direction of the lower resistance element (220, 320), wherein the measuring terminal (230, 330) is located in the connection. [16] Sensor (50) according to one of the preceding claims, - wherein in the second measuring path (200) and / or in the third measuring path (300), the upper resistance elements (210, 310) have a bottom connection in the y-direction, which is connected to a supply connection (Vcc, Vss), and / or - wherein in the second measuring path (200) and / or in the third measuring path (300) the lower resistance elements (220, 320) have a bottom connection in the y-direction which is connected to a supply connection (Vcc, Vss). [17] Sensor (50) according to one of the preceding claims, wherein the x-axis is orthogonal to the y-axis. [18] Sensor (50) according to one of the preceding claims, - wherein the first evaluation circuit (AW1) is a differential amplifier, and / or - wherein the second evaluation circuit (AW2) is a differential amplifier. [19] Method for evaluating a sensor (50) according to one of the preceding claims, wherein the method comprises the following steps: - reading out a first output signal of the first evaluation circuit (AW1) and / or a second output signal of the second evaluation circuit (AW2), - Detecting a zero crossing in one of the output signals, and - In response to this, detection of a pole passage. [20] Method according to claim 19, - where a direction of rotation is detected at the zero crossing of one output signal based on a sign of the other output signal. [21] Method according to one of claims 19 or 20, - where in response to an error condition or to a request - a supply of the first measuring path (100) and the fourth measuring path (400) is switched off, or - a supply of the second measuring path (200) and the third measuring path (300) is switched off. [22] Method according to one of claims 19 to 21, - where zero crossings of both output signals are determined, and - wherein pole passages determined by means of the first output signal and pole passages determined by means of the second output signal are compared against each other. [23] Method according to one of claims 19 to 22, - where, if three zero crossings of an output signal are detected within a given period of time, a common zero crossing is formed from these three zero crossings before further processing steps. [24] Method according to one of claims 19 to 23, - wherein an interference field is detected in response to a mean value of the second output signal deviating from the zero point by at least a predetermined value for a predetermined period of time. [25] Method according to one of claims 19 to 24, - wherein, in response to three zero crossings being detected in the first output signal within a predetermined period of time, an error condition relating to an excessively strong excitation magnetic field and / or to an excessively large pole spacing is detected. [26] Method according to one of claims 19 to 25, - where a zero crossing is detected when an output signal crosses a predetermined value, or an average value of the signal, - where an average - upper and lower limits of the signal, - from upper and lower maximum values ​​of the signal, and / or - as the effective value of the signal.

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