Position measuring device

Abstract

The invention relates to a position measuring device comprising a first component group (1; 1 ') and a second component group (2), the component group (1; 1 ', 2) are movably arranged relative to each other in the measuring direction (x). The first component group (1; 1 ') has: a first circuit board (1.1), which comprises a detection unit (1.11, 1.12, 1.13, 1.14); and a second circuit board (1.2) comprising a magnetic domain wall conductor (1.211). The first printed circuit board (1.1) is arranged offset in the measurement direction (x) relative to the second printed circuit board (1.2). The second component group (2) comprises scales (2.1, 2.2) and magnets (2.3, 2.4). The scales (2.1, 2.2) are arranged between the magnets (2.3, 2.4) and the second circuit board (1.2). The magnets (2.3, 2.4) are arranged in such a way that, when the magnets (2.3, 2.4) travel, a movement of the domain wall can be generated in the domain wall conductor (1.211) by means of the magnets (2.3, 2.4).

Description

TECHNICAL FIELD

[0001] The invention relates to a position measuring device according to claim 1, having a domain wall memory for storing revolution information or position information, for example for an angle measuring device or a length measuring device. BACKGROUND

[0002] For example, angle measuring devices are used as rotary encoders for determining the angular position of two mechanical components that are rotatable relative to one another. For this purpose, so-called multi-turn angle measuring devices are often used, by means of which an absolute position determination can be made over a plurality of revolutions.

[0003] Furthermore, length measuring devices are known in which linear movements of two mechanical components that are movable relative to one another are measured. In particular in length measuring devices that measure relatively large lengths, a plurality of linear scales or identical scales are often arranged next to one another in the measuring direction. In this type of length measuring device, an absolute position determination should be possible over the entire measuring length, at best.

[0004] In general, measuring devices or measuring devices of this type are used in electric drive devices in order to determine the relative movement or the relative position of the respective mechanical components. In this case, the position values generated are supplied to subsequent electronics via a corresponding interface assembly in order to operate the drive device.

[0005] For a plurality of applications of position measuring devices, in particular angle measuring devices or length measuring devices, it is important to store at least the revolution quantity or the coarse position in a non-volatile manner.

[0006] A position measuring device for measuring an angular position is described in the applicant's EP 4 170 289 A1, which is based on an inductive measuring principle.

[0007] Furthermore, the document EP 3 387 387 B1 discloses a magnetic revolution counter having a domain wall memory. SUMMARY

[0008] It is the task of the present invention to provide a position measuring device having a domain wall memory, which is simple and space-saving to construct and works precisely.

[0009] According to the invention, this task is solved by the features of claim 1.

[0010] Correspondingly, the position measuring device comprises a first component group and a second component group, wherein the component groups are movably arranged relative to one another in a measuring direction. The first component group has a first circuit board, which comprises a detection unit. Furthermore, the first component group has a second circuit board, which comprises a domain wall conductor. The first circuit board is arranged offset in the measuring direction relative to the second circuit board. The second component group comprises a scale and at least one magnet. The scale is arranged between the magnet and the second circuit board. In order to determine the relative position between the scale and the detection unit in the measuring direction, the scale can be scanned by the detection unit. The at least one magnet is constructed and arranged such that, when the magnet travels past, a movement of at least one domain wall in the domain wall conductor can be generated by the magnet.

[0011] The domain wall conductor is made of magnetizable material and is designed as at least one conductor track or conductor line or nanowire in particular in connection with the present application. The domain wall conductor extends on a substrate. In the domain wall conductor, information can be stored in the form of oppositely polarized regions (domains). The domains are separated along the conductor track by so-called domain walls, which can be moved by a magnetic field, wherein the position of the domains changes. A domain wall conductor of this type can be enclosed by a housing comprising electronic connection points, such as pins, leads or solder balls. The housing serves to fasten the domain wall memory on the second circuit board.

[0012] The scale can be applied, for example, on a first side of the substrate, and at an oppositely disposed side of the substrate, at least one magnet can be arranged. Alternatively, the scale can be applied on the at least one magnet, such that the magnet serves as a carrier substrate, which reduces the number of required components of the second component group.

[0013] Advantageously, the domain wall conductor is arranged in a housing, which fits on a first surface of the second circuit board. A first distance between the scale and the detection unit has a first length. A second distance between the first surface and the scale has a second length. It applies that the first length is smaller than or at least equal to the second length. The first distance and the second distance or the first length and the second length extend in a third direction, which is oriented orthogonally to the measuring direction.

[0014] In case the scale or the detection unit should be designed such that it extends along the direction of the first distance, it applies that the first length is the shortest length.

[0015] A further design of the present application, a third distance extending between the domain wall conductor and the scale has a third length. A first length of the first distance between the scale and the detection unit is smaller than or at least equal to the third length.

[0016] The magnetic domain wall memory comprises, inter alia, a planar substrate, and the magnetic domain wall conductor is designed as a conductor track on the substrate. In this case, the plane in which the magnetic domain wall conductor extends is planar. Alternatively, the plane can also be designed in a curved manner, in particular if the magnetic domain wall conductor is arranged opposite a magnet having a curved surface.

[0017] The structural width of the magnetic domain wall conductor is typically less than 500 nm, often less than 300 nm, and the thickness or layer thickness of the magnetic domain wall conductor is less than 60 nm. The magnetic domain wall memory can have a plurality of magnetic domain wall conductors.

[0018] The magnetic domain wall memory furthermore has a reading element by means of which the local magnetization state of the magnetic domain wall conductor can be determined (at the respective position of the reading element). Thus, the magnetization state of the magnetic domain wall conductor can be determined by means of the reading element, respectively. The reading element is arranged fixedly in relation to the position of the magnetic domain wall conductor. As a reading element, for example, a GMR sensor or a TMR sensor can be considered. Thus, the magnetic domain wall memory comprises one or a plurality of magnetic domain wall conductors, a substrate, a reading element and a housing.

[0019] According to a further embodiment of the application, the first circuit board and the second circuit board are embodied in each case in a plurality of layers, such that they comprise a plurality of electrically conductive layers. Here, the layer structure of the first circuit board can differ from the layer structure of the second circuit board. The first circuit board and the second circuit board can in particular have a different number of layers. However, for example, the electrically conductive layer thickness of the first circuit board can also differ from the layer thickness of the second circuit board. Exemplarily, the first circuit board and the second circuit board can also be made of different materials. On the other hand, one of the circuit boards can be equipped on one side, and the other of the circuit boards can be equipped on both sides. In particular, the first circuit board and the second circuit board can be arranged relative to one another such that they have surfaces extending in different geometric planes, wherein the circuit boards are in particular arranged offset relative to one another.

[0020] Advantageously, the position-measuring apparatus is embodied such that the operating principle thereof is based on an inductive measuring principle, wherein the detection unit then has at least one receiving conductor track.

[0021] Alternatively or additionally, a magnetic or optical operating principle can also be used. In the latter case, the detection unit can comprise a photodiode or a photodiode array at the first circuit board. Likewise, a light source, for example an LED, can then be fitted at the first circuit board. In the case of a reflective scanning, the scale then consists of reflective scale regions and non-reflective scale regions. Alternatively, a transmission method can also be used, in which the scale consists of opaque scale regions and transparent scale regions, and the light source is then not fitted at the first circuit board.

[0022] Advantageously, the position-measuring device is designed as an angle-measuring device, such that the measuring direction corresponds to a circumferential direction.

[0023] In another design of the application, the first circuit board is designed in the shape of a ring segment, in particular a horseshoe, and extends over an angle of at least 180°, in particular at least 200°, in particular at least 270°, in the measuring direction.

[0024] The second circuit board can thus also be designed in the shape of a ring segment. The second circuit board extends over an angle of less than 180°, in particular less than 120°, in particular less than 90°, in the measuring direction.

[0025] Advantageously, the material of the at least one magnet comprises a plastic with a magnetizable filler. In particular, at least one of the magnets can be produced by a pressing method or an injection-molding method.

[0026] Advantageously, the first component group and the second component group are arranged rotatably relative to one another about an axis, and the face in which the domain wall conductor extends does not intersect the axis or is not penetrated by the axis.

[0027] The domain wall conductor is thus radially offset relative to the axis, an arrangement which is often also referred to as off-axis.

[0028] In another design of the application, the second component group comprises at least two magnets which are arranged in the measuring direction relative to one another. Advantageously, the second component group comprises two identically designed magnets.

[0029] Advantageously, the magnets which are arranged in the measuring direction relative to one another are magnetized such that their magnetization direction extends with a directional component normal to the face in which the domain wall conductor extends. Furthermore, the magnets are arranged such that they have opposite magnetization directions. Furthermore, the magnets are arranged and designed such that the spacing between the first magnet and the second magnet in the measuring direction is not the same along a second direction which is oriented normal to the measuring direction. The face in which the domain wall conductor extends extends along the measuring direction on the one hand and along the second direction on the other hand. A normal vector of the face is oriented in a third direction. In other words, the measuring direction is oriented normal to the second direction and normal to the third direction.

[0030] There is thus a gap between the first magnet and the second magnet, which extends in the measuring direction and whose length in the measuring direction is not the same along the second direction. The profile of the end of the magnets which is opposite in the measuring direction is in particular designed such that the profile diverges at least in the region which extends in the second direction.

[0031] Advantageously, the magnets are arranged in the measuring direction in such a way that they are aligned with respect to one another such that the magnets do not touch. That is, the smallest distance between the first magnet and the second magnet in the measuring direction is therefore greater than zero.

[0032] Due to the fact that there is a distance between the first magnet and the second magnet in the measuring direction, there is an intermediate space in this region, which is composed of air or is filled by a substantially non-magnetic material.

[0033] The magnetization direction is to be understood as the direction of the connecting line between the north pole and the south pole of the magnet. Preferably, the magnet is magnetized through the thickness.

[0034] In a further design of the application, at least one of the magnets is designed in such a way that it has an asymmetric shape with respect to a line running parallel to the measuring direction and orthogonal to the magnetization direction. This asymmetry can be achieved, inter alia, by designing at least one end of the magnet asymmetrically.

[0035] Advantageously, at least one of the magnets is designed at its end in such a way that the contour of this end runs curvedly.

[0036] In the case where the position-measuring device is designed as an angle-measuring device, the second direction runs in the radial direction or in the axial direction (roller arrangement), and the measuring direction corresponds to the circumferential direction or the tangential direction. In this case, the second direction is always oriented orthogonally to the measuring direction as well. Furthermore, the second direction runs orthogonally to the magnetization direction.

[0037] The geometric considerations described here apply to the spatial region in which the relevant magnet is arranged opposite the domain wall conductor, so to speak, from the "point of view" of the domain wall conductor. For example, even if the magnet is rotated, the magnetization direction runs from the domain wall conductor orthogonally to the face of the domain wall conductor.

[0038] There is a fourth distance between the domain wall conductor and the magnet, which has a fourth length. The fourth length or the fourth distance extends orthogonally to the face in which the domain wall conductor runs, i.e. in the third direction, wherein the smallest distance between the magnets in the measuring direction is less than half the fourth length. In the case where the fourth length is not the same over the entire face of the domain wall conductor, it applies in particular that the smallest distance between the magnets is less than half the shortest fourth length.

[0039] Advantageously, the domain wall conductor is positioned with respect to the second direction such that the domain wall conductor is passed by the magnets in a region of the spacing between the two magnets which is smaller than the maximum spacing. When the magnets travel past the domain wall conductor, the domain wall conductor is in a region of the spacing between the magnets which is relatively small, and is influenced by the magnetic field lines which exist there. In particular, the domain wall conductor is positioned with respect to the second direction such that the domain wall conductor is passed by the magnets in a region of the minimum spacing. Thus, when the magnets travel past the domain wall conductor, the domain wall conductor is in a region of the minimum spacing of the magnets, and is influenced by the magnetic field lines which exist there.

[0040] The position measuring device can be used as an angle measuring device, in which, in particular, a number of revolutions is stored. Alternatively, the position measuring device can be designed as a length measuring device with a linear scale to measure linear movements. The scale can comprise, in particular, a first scale member and a second scale member. The first scale member and the second scale member can be arranged in line with one another along the measurement direction, for example, so that a relatively large measurement length can be achieved. In practice, it is also possible for more than just two scale members to be arranged in line with one another. The magnets are then arranged in such a way that they are offset from one another along the first direction. The respective position information can be stored by the domain wall memory, so that it can be determined which of the scale members is being scanned.

[0041] Advantageous configurations of the application are known from the dependent claims. BRIEF DESCRIPTION OF DRAWINGS

[0042] Further details and advantages of the position measuring device according to the application result from the following description of embodiments according to the drawings.

[0043] wherein:

[0044] Figure 1 a perspective exploded view of a position measuring device according to a first embodiment is shown,

[0045] Figure 2 a top view of a first component group of the position measuring device is shown,

[0046] Figure 3 a top view of a second component group of the position measuring device is shown,

[0047] Figure 4 a top view of two magnets of the second component group is shown,

[0048] Figure 5 a top view of a domain wall conductor is shown,

[0049] Figure 6 a sectional view of a detail of the position measuring device is shown,

[0050] Figure 7A sectional view showing details of a position measuring device according to a second embodiment is shown. DETAILED DESCRIPTION

[0051] In Figure 1 a position measuring device is shown, which comprises a first component group 1 and a second component group 2, wherein the component groups 1, 2 are arranged rotatably relative to one another about an axis A. Position measuring devices of this type are used as angle measuring devices. Figure 1 is a perspective exploded view, such that the spacing between the first component group 1 and the second component group 2 is greater than in the case of an actual operation of the position measuring device.

[0052] The first component group 1 comprises a first circuit board 1.1 having a plurality of layers and electronic components. The first component group 1 also comprises a frame 1.3 as a mechanical support structure.

[0053] As is also shown in Figure 2 , the first circuit board 1.1 has the shape of a circular ring segment, which is designed in a manner that encircles approximately 300° and accordingly has an opening. Arranged externally about the first circuit board 1.1, a closed and substantially ring-shaped frame 1.3 (here made of metal) is fastened, which serves, inter alia, for mechanically reinforcing the first component group 1 and has fastening regions 1.31 in the form of holes here. In the region of the opening of the first circuit board 1.1, a bridge 1.32 of the frame 1.3 extends substantially in radial direction parallel to the end side of the first circuit board 1.1. A further bridge 1.33 of the frame 1.3 extends in a circular segment contour over an angle of approximately 60°.

[0054] According to this embodiment, the second component group 2 has an approximately ring-shaped outer shape (see Figure 1 and Figure 3 ). The second component group comprises a first scale 2.1 and a second scale 2.2 on the end side, wherein the scales 2.1, 2.2 extend in the measurement direction x.

[0055] The scales 2.1, 2.2 are applied here on a substrate 2.5, which is made of a circuit board material in the shown embodiment. The scales 2.1, 2.2 are configured annularly and are arranged on different radii of the substrate 2.5 concentrically with respect to the axis A.

[0056] According to Figure 3The scales 2.1, 2.2 comprise a graduation structure which consists of a periodic sequence of electrically conductive graduation regions 2.11, 2.21 and non-conductive graduation regions 2.12, 2.22, respectively, which are arranged alternately along the measurement direction x or the circumferential direction. The electrically conductive graduation regions 2.11, 2.21 are composed of an electrically conductive material layer, respectively. In the example shown, copper is applied to the substrate 2.5 as the material for the electrically conductive graduation regions 2.11, 2.21. In contrast, in the non-conductive graduation regions 2.12, 2.22, the substrate 2.5 is not coated. By arranging the two scales 2.1, 2.2, respectively, the angular position of the second component group 2 can be determined absolutely. The outer second scale 2.2 has a greater number of the respective graduation regions 2.21, 2.22 along the circumferential direction x, so that a higher resolution with regard to the angular position measurement is achievable by the second scale.

[0057] Furthermore, on the side of the substrate 2.5 which is opposite the scales 2.1, 2.2, a first magnet 2.3 and a second magnet 2.4 are arranged, wherein the magnets 2.3, 2.4 are associated with the second component group 2. The magnets 2.3, 2.4 and the substrate 2.5 are thus fixedly connected to one another and move at the same speed or rotational speed, respectively. The magnets 2.3, 2.4 are arranged in alignment with one another in the measurement direction x, which here corresponds to the circumferential direction, and have a center line L1, L2, respectively, which extends in the measurement direction x (see also Figure 4 ).

[0058] In the proposed embodiment, the magnets 2.3, 2.4 are designed as plastic-bonded magnets. Accordingly, they comprise a plastic with magnetizable filler or magnetic powder. The filler is embedded in the plastic matrix. In particular, the magnets 2.3, 2.4 can be implemented as compression magnets, wherein the magnetizable filler is embedded in a thermosetting plastic matrix, for example, epoxy resin. Alternatively, the magnets 2.3, 2.4 can also be produced in an injection molding process.

[0059] The magnets 2.3, 2.4 are arranged such that they have opposite magnetization directions D1, D2. Furthermore, the magnets 2.3, 2.4 are designed as permanent magnets and are magnetized by thickness, respectively, i.e. such that their magnetization directions D1, D2 are oriented axially here. The magnets 2.3, 2.4 have opposite magnetization directions D1, D2. In the proposed embodiment, the two magnets 2.3, 2.4 are identical, which facilitates assembly and storage.

[0060] The end portions of the magnets 2.3, 2.4 are designed such that they are tapered. Accordingly, the first magnet 2.3 and the second magnet 2.4 are designed such that, when the spacing u, U between the first magnet 2.3 and the second magnet 2.4 extending in the measurement direction x is determined at different points along the second direction y, the spacing changes. In particular, the first magnet 2.3 and the second magnet 2.4 are designed such that the spacing u, U between the first magnet 2.3 and the second magnet 2.4 extending in the measurement direction x changes when the first magnet 2.3 and the second magnet 2.4 are moved relative to one another.Figure 4 In this case, the spacing u, U increases along a second direction y, indicated by an arrow. The second direction y runs orthogonally to the measurement direction x, that is to say, in this case radially to the axis A or in a radial direction. The spacing u, U is thus not the same along the second direction y or as a function of the position along the second direction y. The profile of the ends of the magnets 2.3, 2.4 which are opposite one another is designed mirror-symmetrically about a symmetry axis which is oriented parallel to the second direction y. Furthermore, the ends of the magnets 2.3, 2.4 are designed such that their profile runs asymmetrically about a line which is oriented parallel to the measurement direction x, in particular about the centre line L1, L2. In the region in which the spacing u, U between the magnets 2.3, 2.4 varies in the measurement direction x, the first magnet 2.3 and the second magnet 2.4 or their profile are designed such that the spacing u, U varies continuously along the second direction y, that is to say, the profile is configured here as a smooth curve along the second direction y and without steps.

[0061] In order to determine the angle information, according to Figure 2 The first circuit board 1.1 has a first detection unit 1.11, a second detection unit 1.12, a third detection unit 1.13 and a fourth detection unit 1.14. The detection units 1.11 to 1.14 each have a ring segment-like shape, wherein it applies to all detection units 1.11 to 1.14 that a centre point M of the respective ring segment-like shape lies on the axis A. Correspondingly, the detection units 1.11 to 1.14 are approximately concentrically arranged opposite one another about the centre point M.

[0062] The first detection unit 1.11 comprises a first excitation track 1.111 and a first receiving conductor line 1.112. Likewise, the second detection unit 1.12 comprises a second excitation track 1.121 and a second receiving conductor line 1.122, the third detection unit 1.13 comprises a third excitation track 1.131 and a third receiving conductor line 1.132, and the fourth detection unit 1.14 comprises a fourth excitation track 1.141 and a fourth receiving conductor line 1.142.

[0063] The excitation tracks 1.111, 1.121, 1.131, 1.141 each enclose the respective receiving conductor line 1.112, 1.122, 1.132, 1.142. The excitation tracks 1.111, 1.121, 1.131, 1.141 and the receiving conductor lines 1.112, 1.122, 1.132, 1.142 run along the measurement direction x.

[0064] In the proposed embodiment, each detection unit 1.11, 1.12, 1.13, 1.14 comprises four reception conductor lines 1.112, 1.122, 1.132, 1.142, which are arranged offset in the measurement direction x or circumferential direction, so that they can provide four phase-shifted signals in correspondence with this offset. In the proposed embodiment, adjacent reception conductor lines 1.112, 1.122, 1.132, 1.142 within a detection unit 1.11, 1.12, 1.13, 1.14 are arranged offset from one another by 1 / 8 of a complete sinusoidal period (n / 4 or 45° along the circumferential direction x).

[0065] In Figure 2 In the proposed embodiment, each detection unit 1.11, 1.12, 1.13, 1.14 comprises four reception conductor lines 1.112, 1.122, 1.132, 1.142, which are arranged offset in the measurement direction x or circumferential direction, so that they can provide four phase-shifted signals in correspondence with this offset. In the proposed embodiment, adjacent reception conductor lines 1.112, 1.122, 1.132, 1.142 within a detection unit 1.11, 1.12, 1.13, 1.14 are arranged offset from one another by 1 / 8 of a complete sinusoidal period (n / 4 or 45° along the circumferential direction x).

[0066] The reception conductor lines 1.112, 1.122, 1.132, 1.142 of the detection units 1.11, 1.12, 1.13, 1.14 are electrically interconnected in such a way that they provide 0° and 90° signals on the one hand and 45° and 135° signals on the other hand. From the 0° and 90° signals, a first position signal can be determined, and from the 45° and 135° signals, a second position signal can be determined, which is redundant with respect to the first position signal.

[0067] In addition, the first component group 1 comprises a second circuit board 1.2, which is designed in the manner of a ring segment and, in the proposed embodiment, extends over an angle of approximately 52°. On the second circuit board 1.2, a magnetic domain wall memory 1.21 is fitted. According to Figure 5The domain wall memory 1.21 comprises a domain wall conductor 1.211 and a substrate 1.212, wherein the domain wall conductor 1.211 is applied in the form of a conductor circuit on the substrate 1.212 and extends in (or on) a first face XY. The domain wall conductor 1.211 has a domain wall generator 1.2111 at one end. In the proposed embodiment, the substrate 1.212 has a mechanically supported silicon layer, wherein the substrate 1.212 is designed planarly and the domain wall conductor 1.211 can be part of a CMOS chip. Alternatively, the substrate can have a glass layer. The domain wall conductor 1.211 comprises a soft magnetic material, for example a Ni-Fe alloy. The domain wall conductor 1.211 can be designed as an open spiral as shown in Figure 5 , or can have a closed course.

[0068] In the operation of the position-measuring device, the first component group 1 and the second component group 2 are arranged opposite one another. In the proposed embodiment, the first component group 1 can operate as a stator and the second component group 2 can operate as a rotor. The first circuit board 1.1 serves for scanning the scales 2.1, 2.2. In the proposed embodiment, the electronic components are only assembled on one side of the first circuit board 1.1, namely on the side facing away from the scales 2.1, 2.2. The domain wall memory 1.21 serves for ensuring a multi-turn function, i.e. for counting a number of turns or operating times. The domain wall memory 1.21 is arranged such that the face XY in which the domain wall conductor 1.211 extends (or is arranged) is oriented orthogonally to the magnetization direction D1, D2.

[0069] In Figure 6 , a partial sectional view through the first component group 1 and the second component group 2 is shown (see Figure 2 E-E). Here, the first circuit board 1.1 has a total of six electrically conductive layers. The first circuit board 1.1 can be divided into two halves in such a way that it is divided by an imaginary plane extending in the x, y direction. The electrically conductive layers in the half of the first circuit board 1.1 facing the scales 2.1, 2.2 (in Figure 6 the lower half) are constructed such that they form the detection cells 1.11 to 1.14. In contrast, the other three electrically conductive layers in the upper half of the first circuit board 1.1 in Figure 6 are used for connecting the electronic components of the circuit.

[0070] The second circuit board 1.2 can be constructed more simply and, in the proposed embodiment, has only four electrically conductive layers. These four electrically conductive layers serve to connect the electronic components of the circuit which is ultimately used to count the number of turns or operating cycles. The domain wall memory 1.21 has a housing 1.213 with electrical connection points in which the domain wall conductor 1.211 is arranged together with a substrate 1.212. The housing 1.213 is fitted on the first surface O1.2 of the second circuit board 1.2.

[0071] In order to be able to position the second circuit board 1.2 accurately in a simple manner during the fitting of the first component group 1, the frame 1.3 and the second circuit board 1.2 have suitable guide surfaces.

[0072] There is an air gap between the component groups 1, 2 which extends in the third direction z. A first distance extends in the third direction z between the scale 2.1 and such a layer of the first circuit board 1.1 which is closest to the scale 2.1 and in which at least part of the detection unit 1.11, 1.12, 1.13, 1.14, in particular a section of the reception conductor track 1.112, 1.122, 1.132, 1.142, is arranged. The first distance has a first length S1. A second distance which extends between the scale 2.1 and the first surface O1.2 has a second length S2. Here, the first length S1 is smaller than the second length S2, so that the condition S1 < S2 is met. Furthermore, a third distance which extends between the domain wall conductor 1.211 and the scale 2.1 has a third length S3, wherein here the first length S1 is smaller than the third length S3, so that here too the criterion S1 < S3 is met.

[0073] Thus, in the assembled state, the detection units 1.11, 1.12, 1.13, 1.14 and the scales 2.1, 2.2 are arranged axially spaced or with a gap relative to one another, so that, upon relative rotation between the first component group 1 and the second component group 2, a signal dependent on the respective angular position can be generated in the receiving conductor tracks 1.112, 1.122, 1.132, 1.142 by means of an inductive effect, respectively. A prerequisite for the formation of the respective signal is that the excitation track 1.111, 1.121, 1.131, 1.141 generates a temporally varying electromagnetic excitation field in the region of the respective scanned scale structure. In the embodiment shown, the excitation track 1.111, 1.121, 1.131, 1.141 is configured as a plurality of planar parallel current-carrying individual conductor tracks. The first circuit board 1.1 has an electronic circuit with electronic components which are electrically connected to one another. The electronic circuit can also comprise an ASIC module, for example. The signals generated by the receiving conductor tracks 1.112, 1.122, 1.132, 1.142 are further processed by means of several of the electronic components which form an evaluation circuit. The electronic circuit of the scanning element 1 not only functions as an evaluation element, but also as an excitation control element, under the control of which an excitation current is generated or produced which then flows through the excitation track 1.111, 1.121, 1.131, 1.141. Thus, the excitation track 1.111, 1.121, 1.131, 1.141 is energized by one and the same excitation control element.

[0074] If the excitation track 1.111, 1.121, 1.131, 1.141 is energized, an electromagnetic field of tubular or cylindrical orientation is configured around the excitation track 1.111, 1.121, 1.131, 1.141. The field lines of the generated electromagnetic field extend around the excitation track 1.111, 1.121, 1.131, 1.141, wherein the direction of the field lines depends in a known manner on the current direction in the excitation track 1.111, 1.121, 1.131, 1.141. In the region of the electrically conductive scale region 2.11, 2.21, eddy currents are induced, so that a respective angular position-dependent field modulation is achieved. The relative angular position can be measured by means of the receiving conductor tracks 1.112, 1.122, 1.132, 1.142, respectively, accordingly.

[0075] If the magnetic field moving relative to the magnetic domain wall conductor 1.211 acts on the magnetic domain wall conductor 1.211 in a suitable manner, the magnetic domain wall moves within the magnetic domain wall conductor 1.211 or along the magnetic domain wall conductor 1.211. In order to form an optimum magnetic field, a magnet assembly having magnets 2.3, 2.4 as described above is used, which have a tapering at the respective ends of the magnets 2.3, 2.4 facing each other. It has proven to be extremely advantageous if the respective profile of one end of the magnets 2.3, 2.4 extends curvedly, as in this embodiment, so that the magnets 2.3, 2.4 have a concave section at their ends, respectively. In order to equalize the magnetic field in the transition area from the first magnet 2.3 to the second magnet 2.4, the minimum distance u is here chosen to be greater than zero. Furthermore, the minimum distance u between the first magnet 2.3 and the second magnet 2.4 is dimensioned so that it is smaller than half the length S4 of the fourth distance between the magnetic domain wall conductor 1.211 and the magnets 2.3, 2.4 (u < 1 / 2 * S4).

[0076] The magnetic domain wall conductor 1.211 is positioned with respect to the second direction y so that it is traversed by the magnets 2.3, 2.4 in the region of the minimum distance u. Now, if the magnets 2.3, 2.4 are moved relative to the magnetic domain wall conductor 1.211 in the measuring direction x, a quasi-rotating magnetic field acts on the magnetic domain wall conductor 1.211 in the plane of the magnetic domain wall conductor 1.211, i.e. in the plane XY, at the ends and in particular in the region of the gap between the magnets 2.3, 2.4. As a result, the position of the magnetic domain wall moves, wherein the movement field is generated by the magnets 2.3, 2.4 being guided past the magnetic domain wall conductor 1.211.

[0077] After each passage of the ends of the magnets 2.3, 2.4 past the magnetic domain wall conductor 1.211 or after each half revolution of the second component group 2, the magnetic domain wall or the magnetic domain walls continue to move.

[0078] The magnetization direction within the section of the magnetic domain wall conductor 1.211 and thus the position of the magnetic domain wall can be detected by read elements integrated in the magnetic domain wall memory 1.21. In this way, the number of revolutions can be counted or the revolution information can be stored in an angle measuring device even if no auxiliary energy is available. This is important, for example, if the shaft moves due to a weight load when the current fails. Furthermore, the magnetic domain wall moves depending on the direction of rotation so that the magnetic domain wall memory 1.21 can be reliably used in applications that allow two directions of rotation.

[0079] The relatively accurate determination of the angular position within one revolution is achieved from the scanning of the scale 2.1, 2.2 by the detection units 1.11, 1.12, 1.13, 1.14. In order to determine the angular position absolutely within a plurality of revolutions, the angular position determined with the scanning device 1.12 (fine position) must be synchronized with the revolution information of the domain wall conductor 1.211 (coarse position).

[0080] In Figure 7 a second embodiment is shown. The embodiment differs from the first embodiment essentially in that the first surface O1.2' of the second circuit board 1.2 is now arranged facing the scale 2.1, 2.2.

[0081] The housing 1.213 is fitted on the first surface O1.2' of the second circuit board 1.2. Accordingly, in the second embodiment, the first distance has the length S1 unchanged. In contrast, the second distance extending between the scale 2.1 and the first surface O1.2' has a second length S2', which here is smaller than the second length S2 according to the first embodiment. Nonetheless, it also applies in the second embodiment that the first length S1 is smaller than the second length S2', so that the criterion (S1 < S2') is fulfilled. Furthermore, the third distance extending between the domain wall conductor 1.211 and the scale 2.1 has a third length S3'. It also applies in the second embodiment that the first length S1 is smaller than the third length S3', in general S1 < S3' should apply.

[0082] According to Figure 2 the magnet assembly according to the first embodiment can also be used in the second embodiment. Accordingly, it also applies here that the minimum spacing u between the first magnet 2.3 and the second magnet 2.4 is dimensioned such that it is smaller than half the fourth distance length S4' between the domain wall conductor 1.211 and the magnets 2.3, 2.4 (u < 1 / 2 * S4').

Claims

1. A position measuring device comprising a first component group (1; 1') and a second component group (2), wherein The component groups (1; 1', 2) are movably arranged relative to one another in a measurement direction (x), wherein - the first component group (1; 1') has a first circuit board (1.1) which comprises a detection unit (1.11, 1.12, 1.13, 1.14), and has a second circuit board (1.2) which comprises a domain wall conductor (1.211), wherein the first circuit board (1.1) is arranged offset relative to the second circuit board (1.2) in the measurement direction (x), and - the second component group (2) comprises a scale (2.1, 2.2), and a magnet (2.3, 2.4), wherein the scale (2.1, 2.2) is arranged between the magnet (2.3, 2.4) and the second circuit board (1.2), wherein for determining a relative position in the measurement direction (x), the scale (2.1, 2.2) is scannable by the detection unit (1.11, 1.12, 1.13, 1.14), and the magnet (2.3, 2.4) is constructed and arranged such that, upon the magnet (2.3, 2.4) travelling past, a movement of a domain wall in the domain wall conductor (1.211) is producible by the magnet.

2. The position measuring apparatus of claim 1, wherein, The domain wall conductor (1.211) is arranged in a housing (1.213) which is fitted on a first surface (01.2; 01.2') of the second circuit board (1.2), wherein - a first distance between the scale (2.1, 2.2) and the detection unit (1.11, 1.12, 1.13, 1.14) has a first length (S1), and - a second distance between the first surface (01.2; 01.2') and the scale (2.1, 2.2) has a second length (S2; S2'), wherein it applies that the first length (S1) is smaller than or equal to the second length (S2; S2').

3. The position measuring device according to claim 1 or 2, wherein - a first distance between the scale (2.1, 2.2) and the detection unit (1.11, 1.12, 1.13, 1.14) has a first length (S1), and - a third distance between the domain wall conductor (1.211) and the scale (2.1, 2.2) has a third length (S3; S3'), wherein it applies that the first length (S1) is smaller than or equal to the third length (S3; S3').

4. The position measuring apparatus of any of the preceding claims, wherein, The first circuit board (1.1) and the second circuit board (1.2) are respectively implemented in multiple layers, wherein the layer structure of the first circuit board (1.1) is different from the layer structure of the second circuit board (1.2).

5. The position measuring apparatus of any one of the preceding claims, wherein, The position measuring device is based on an inductive measuring principle, and the detection unit (1.11, 1.12, 1.13, 1.14) has at least one receiving conductor track (1.112, 1.122, 1.132, 1.142).

6. The position measuring apparatus of any one of the preceding claims, wherein, The position measuring device is designed as an angle measuring device.

7. The position measuring apparatus of claim 6, wherein, The first circuit board (1.1) is designed in the form of a ring segment and extends over an angle of at least 180°.

8. The position measuring apparatus of claim 6 or 7, wherein, The second circuit board (1.2) is designed in the form of a ring segment and extends over an angle of less than 180°.

9. The position measuring apparatus of any of the preceding claims, wherein, The material of the magnets (2.3, 2.4) comprises a plastic with a magnetizable filler.

10. The position measuring apparatus of any of the preceding claims, wherein, The component group (1; 1', 2) is arranged rotatably relative to one another about an axis (A), and the plane (XY) in which the domain wall conductor (1.11) extends does not intersect the axis (A).

11. The position measuring apparatus of any of the preceding claims, wherein, The second component group (2) comprises at least two magnets (2.3, 2.4).

12. The position measuring apparatus of claim 11, wherein, The magnets (2.3, 2.4) - are arranged in alignment with one another in a measurement direction (x), - are magnetized such that their magnetization directions (D1, D2; D1', D2') extend with a directional component normal to the plane (XY), - are arranged such that they have opposite magnetization directions (D1, D2), wherein The magnets (2.3, 2.4) are arranged and designed such that the spacing (u, U) between the first magnet (2.3) and the second magnet (2.4) in the measurement direction (x) is not the same along a second direction (y) oriented normal to the measurement direction (x).

13. The position measuring apparatus of claim 11 or 12, wherein, The magnets (2.3, 2.4) are arranged in alignment with one another in a measurement direction (x) such that the magnets do not touch.

14. The position measuring apparatus of claim 11, 12 or 13, wherein, A fourth distance exists between the domain wall conductor (1.11) and the magnets (2.3, 2.4), which fourth distance extends normal to the plane (XY) in which the domain wall conductor (1.11) extends, wherein the fourth distance has a fourth length (S4; S4'), wherein the smallest spacing (u) between the magnets (2.3, 2.4) in the measurement direction (x) is less than half the fourth length (S4; S4').

15. The position measuring apparatus of claims 11 to 14, wherein, At least one of the magnets (2.3, 2.4) is designed at its end such that the contour of the end extends curvedly.

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