Inductive sensor device

Abstract

The invention relates to an inductive sensor device. The device has a scale body with a plurality of electrically conductive conductor loops. The conductor band ring is arranged in at least one scale line in the measurement direction. The sensor unit is movably arranged on the scale body in the measuring direction and has, for each scale row, a coil group comprising a transmitting coil generating a transmitter signal and a receiving coil. Each coil set provides a receiver signal for the evaluation unit to determine an absolute relative position of the sensor unit relative to the scale body in the measurement direction. At least one scale row has a modulation section in which the impedance, in particular the apparent resistance, of the conductor band loop varies in the measurement direction from one end to the other end of the modulation section, whereby the receiver signal is modulated with respect to its phase position relative to the transmitter signal. The modulation is taken into account when the evaluation unit determines the absolute relative position. Therefore, the measuring range for clearly determining the absolute relative position can be expanded. In addition, the position determination is robust for assembly tolerances.

Description

Technical Field

[0001] The invention relates to an inductive sensor device comprising a sensor unit that can be moved along a scale in order to determine the position between the sensor unit and the scale, thereby in particular determining the absolute position between the sensor unit and the scale. Background Art

[0002] For example, such inductive sensor devices are used in measuring devices such as calipers.

[0003] For example, DE 10 2004 026 311 A1 describes an inductive sensor device. Two transmitting coils are arranged in a sensor unit that is movable along a scale, with the transmitting coils surrounded by receiving coils. The scale includes a scale element that can be magnetically coupled to the transmitting and receiving coils, allowing movement of the sensor unit along the scale to be detected.

[0004] Another inductive sensor device is known from DE 102 02 275 B4. The scale element for inductive coupling with the sensor unit comprises two rings connected to each other via a connecting line. To form a vernier scale, these rings are arranged in two rows with different graduations (distances). In this case, the length of the connecting line between the two rings of the common scale element varies. To compensate for the longer length of the connecting line, the conductors of the rings and the width of the connecting line can be modified so that the signal strength (amplitude) is not reduced.

[0005] Furthermore, EP 3 594 629 A1 discloses an inductive sensor device. The scale comprises two rows of scale elements, wherein the scale elements in one row have a first distance between adjacent scale elements, and the scale elements in the other row have a second distance between adjacent scale elements, thereby forming a vernier scale. This allows for an extended measurement range for absolute position measurements between the sensor unit and the scale. Furthermore, the scale elements in one row vary in height, thereby generating an amplitude-modulated signal in the sensor unit during inductive coupling with the scale elements. This allows for an additional extension of the absolute measurement range.

[0006] US Pat. No. 6,335,618 B1 also describes an inductive sensor arrangement according to the vernier principle.

[0007] Among these methods, the use of signal amplitude modulation in the sensor unit is disadvantageous. The amplitude of the signal generated in the sensor unit for position determination is highly dependent on the relative orientation of the sensor unit with respect to the scale. Changing distances and inclinations or tilts lead to changes in the amplitude, which can hinder position determination and increase measurement uncertainty. Furthermore, the amplitude is significantly dependent on the excitation field of the sensor unit's transmitting coil and, therefore, the excitation current flowing through it. Therefore, fluctuations in the excitation current can also negatively impact position determination based on amplitude modulation. Furthermore, temperature deviations can also affect the amplitude, as the resistance of the conductor varies with temperature.

[0008] Amplitude modulation is also disadvantageous because the modulation depth or modulation range is limited. This is because a sufficient signal-to-noise ratio must always be maintained.

[0009] Further inductive sensor devices are described, for example, in EP 0 743 508 A2, EP 3 299 770 A1 and US 2016 / 0146636 A1. Summary of the Invention

[0010] Starting from the prior art, the object of the present invention may be considered to be to provide an economically realizable inductive sensor device which comprises a sufficiently large measuring range for absolute position determination and permits high tolerances for assembly.

[0011] This object is achieved by means of an inductive sensor arrangement having the features of claim 1 .

[0012] The inductive sensor device comprises a scale, a sensor unit, and an evaluation unit. The evaluation unit may be part of the sensor unit. The sensor unit is supported on the scale so as to be movable along a measuring direction. In one embodiment, the scale may extend in a straight line in the measuring direction. Depending on the application (e.g., the configuration of the measuring device in which the inductive sensor device is used), the measuring direction may also have a curved extension, in particular, along a circular arc.

[0013] The scale body comprises a plurality of electrically conductive conductor strip loops. The conductor strip loops are arranged in at least one scale row, preferably in a plurality and in particular in exactly two scale rows. The at least one scale row extends along the measuring direction. If there are multiple scale rows, they are arranged offset relative to one another in a transverse direction. The transverse direction is oriented orthogonally to the measuring direction. It is advantageous if the conductor strip loops are arranged in a common plane, wherein the plane is parallel to the measuring direction and parallel to the transverse direction.

[0014] If there are multiple scale rows, the conductor strip loops in the scale rows are arranged with at least two different graduations, in particular with a first graduation in the first scale row and a second graduation in the second scale row. The first graduation and the second graduation are distinct from one another and preferably form a vernier scale. The graduation in each scale row is preferably constant.

[0015] The graduation is defined by the distance between two reference points in the measuring direction between directly adjacent conductor strip loops in a respective individual graduated row. For example, the reference points can each lie on the center line of the conductor strip loop, wherein the center line extends centrally between the outer edges of each conductor strip of the conductor strip loop.

[0016] If in an embodiment more than two scale rows are present, these additional scale rows can comprise graduations which are distinguishable from the first graduation and the second graduation, wherein, in particular, each scale row present comprises a different graduation.

[0017] The sensor unit has a coil assembly for each provided scale line, wherein the coil assembly includes at least one, and preferably exactly one, transmitter coil and at least one, and preferably two, and in particular exactly two, receiver coils. A transmitter signal can be supplied to the transmitter coil, for example, by means of a transmitter unit of an inductive sensor device. Each receiver coil accordingly supplies a receiver signal to the evaluation unit. The transmitter unit and the evaluation unit can be implemented as separate component assemblies or in a shared control unit. The transmitter unit can be part of the sensor unit, similar to the evaluation unit.

[0018] The evaluation unit is configured to evaluate the receiver signal and thereby determine the absolute relative position between the sensor unit and the scale. Based on this absolute relative position, a measured value can be determined and output, for example, if the inductive sensor device is part of a measuring device.

[0019] When viewed in the measuring direction, the scale row, or at least one of the scale rows, and preferably each scale row, has a modulation segment. The modulation segment is preferably shorter than the total length of the scale row in the measuring direction. Alternatively, in one embodiment, a single modulation segment may extend along the entire scale row in the measuring direction. In each modulation segment, the conductor loops arranged therein have impedances and / or apparent resistances that are distinct from one another. Within the modulation segment, when viewed in the measuring direction, the impedance and / or apparent resistance increase or decrease from one end of the modulation segment to the opposite end of the modulation segment. Preferably, the impedance and / or apparent resistance varies from each conductor loop to the next within the modulation segment. The conductor loop arranged at one end of the modulation segment has the lowest impedance and / or lowest apparent resistance within the modulation segment, while the conductor loop arranged at the opposite end of the modulation segment has the highest impedance and / or highest apparent resistance in the modulation segment.

[0020] Here, apparent resistance is the magnitude of impedance. Impedance has reactance (for example, inductive reactance) and ohmic resistance.

[0021] In the at least one modulation section, the impedance and / or the apparent resistance preferably varies such that the ratio of reactance to ohmic resistance changes.

[0022] Due to the varying impedance and / or apparent resistance in the modulation section, the receiver signal provided by the at least one assigned receiving coil is accordingly influenced and, so to speak, modulated. In this case, an additional parameter is provided that is taken into account during the determination of the absolute relative position.

[0023] Due to the modulation of the receiver signal based on the varying impedance and / or apparent resistance, a robust determination of the absolute relative position can be performed that is insensitive to deviations in the relative orientation of the sensor device's components, in particular, the relative orientation between the sensor unit and the scale. This allows for greater assembly and mounting tolerances and, therefore, economical assembly. Furthermore, the inductive sensor device is insensitive to environmental influences (e.g., varying ambient humidity). If the transmitter signal were an applied transmitter voltage rather than an external transmitter current, the ambient temperature could, in particular, affect the ohmic resistance of the conductor strip loop and / or cause a phase shift in the transmitter signal. However, as will become apparent from the detailed description below, this design can be made insensitive to temperature influences.

[0024] These advantages stem in particular from the fact that the impedance and / or apparent resistance that varies within the modulation section allows for modulation of the phase position of the receiver signal relative to the transmitter signal along the at least one scale line. Phase position here refers to the phase difference between the phase of the at least one receiver signal and the phase of the transmitter signal. Unlike the evaluation of the amplitude in the context of amplitude modulation, this phase position evaluation is much more robust to deviations in the relative orientation between the sensor unit and the scale and is significantly less sensitive to temperature changes or other environmental influences.

[0025] Furthermore, the modulation of the receiver signal according to the invention can be realized using standard components. In particular, no application specific integrated circuit (ASIC) is required in the evaluation unit, but the evaluation unit can be realized by means of a commercially available microcontroller.

[0026] Overall, an economical sensor device can be provided which is robust to assembly errors or assembly deviations (large tolerance range), robust to environmental influences and also allows a long measuring range in the measuring direction for determining the absolute relative position.

[0027] It is advantageous if all conductor strip loops within the at least one modulation section have different impedances and / or apparent resistances. Consequently, the impedance and / or apparent resistance increases or decreases from each conductor strip loop to the immediately adjacent conductor strip loop. In principle, it is also possible to form multiple groups of conductor strip loops within a modulation section, wherein the conductor strip loops of a common group have equal impedances and / or apparent resistances.

[0028] The impedance and / or apparent resistance can vary nonlinearly within the at least one modulation segment along the measurement direction. This means that the change in impedance and / or apparent resistance of the individual conductor strip loops within the modulation segment in the diagram, according to the linearly indicated measurement direction, is not a point on a common straight line, but rather, for example, a point on a curve (nonlinear function).

[0029] The impedance and / or apparent resistance in the at least one modulation segment along the measurement direction can be predefined such that, at a desired operating point, the magnitude of the reactance is equal to the magnitude of the ohmic resistance. When the magnitudes of the reactance and ohmic resistance are equal, small changes in the impedance result in the largest phase change of the receiver signal. Preferably, the operating point is at least substantially the average value of the varying impedance and / or apparent resistance, with the impedance and / or apparent resistance varying upward and downward about this average value by approximately equal amounts.

[0030] It is preferred if the impedance and / or apparent resistance is varied in the at least one modulation section between the conductor strip loops by varying the ratio between reactance and ohmic resistance. Preferably, this variation of the impedance and / or apparent resistance is achieved solely by varying the ohmic resistance, while the reactance of the conductor strip loops remains substantially constant.

[0031] In a preferred embodiment, the impedance and / or apparent resistance between the conductor strip loops within the at least one modulation segment can be varied by varying the conductor strip cross-sections, in particular, the conductor strip widths. Thus, the conductor strip width of the conductor strip loops increases or decreases from one end of the modulation segment to the opposite end of the modulation segment. The conductor strip width is measured perpendicular to its direction of extension, in particular, perpendicular to the outer edges of the conductor strip. Varying the conductor strip width of the conductor strip loops within the modulation segment can be achieved in a very simple manner.

[0032] The change in conductor strip width from one conductor strip loop to another within the modulation section is preferably performed uniformly outward and inward, starting from the center of the conductor strip. Thus, starting from the centerline of the conductor strip, the width increases uniformly on both sides. The greater the conductor strip width, the longer the outer perimeter of the conductor strip loop becomes, and the shorter the inner perimeter of the conductor strip loop becomes. This ensures a constant graduation.

[0033] In a preferred embodiment, the conductor strip loop with the larger conductor strip width has a higher loop height in the lateral direction and / or a larger loop width in the measuring direction.

[0034] To modify the impedance and / or apparent resistance between the conductor strip loops within the at least one modulation section, in addition to or as an alternative to modifying the conductor strip width or conductor strip cross-section, one or more of the following parameters can be modified in any combination: conductor strip thickness, conductor strip cross-sectional shape, conductor strip material. All modifications can be made to the conductor strip as a whole or only locally, at least at one location on the conductor strip.

[0035] The shape of the conductor strip loop can vary. Each conductor strip loop can have at least one straight conductor strip section and / or at least one curved conductor strip section. It is preferred if each conductor strip loop includes two transverse legs extending in a straight line in the transverse direction. These two transverse legs are connected to each other by two longitudinal legs, which are arranged at a distance from each other in the transverse direction. The longitudinal legs can be straight or curved and can extend parallel or obliquely with respect to the measuring direction. In particular, the transverse and longitudinal legs have equal width and define the conductor strip width of the conductor strip loop.

[0036] It is preferred if the conductor strip width within the conductor strip loop does not vary but is instead constant.

[0037] It is advantageous if all conductor tape loops have the same conductor tape thickness. The conductor tape thickness is measured perpendicular to the measuring direction and perpendicular to the transverse direction. If, apart from manufacturing tolerances, all conductor tape loops have the same conductor tape thickness, this facilitates easy and economical production of the conductor tape loops on the scale.

[0038] It is advantageous if at least one of the provided scale rows includes a non-modulated segment or region extending in the measuring direction. Within this non-modulated segment, all conductor loops have substantially equal impedance and / or apparent resistance. For example, a non-modulated segment can be arranged between two modulated segments of a scale row. If one of the scale rows includes a non-modulated segment, at least one other scale row has a modulated segment in this region. If multiple modulated segments are present, they can have equal or different lengths in the measuring direction.

[0039] In the non-modulated sections of the scale row, all conductor strip loops preferably have equal conductor strip width and preferably equal loop height and / or equal loop width.

[0040] It is preferred if the first scale line and the second scale line each have at least one non-modulated section.The non-modulated sections of the first scale line and the second scale line are arranged offset in a non-overlapping manner in the measuring direction.

[0041] Due to the at least one non-modulated segment in one or more scale rows, the measuring range for determining the absolute relative position can be extended.

[0042] The evaluation unit is preferably configured to determine a phase signal from at least one of the receiver signals, wherein the phase signal is, for example, an electrical signal. The phase signal particularly describes a phase shift between a transmitter signal (e.g., the excitation or transmitter coil current through the at least one transmitter coil) and a conductor strip loop current. Due to the transmitter signal applied to the transmitter coil, the conductor strip loop current is induced in one, and in particular, a plurality of, conductor strip loops arranged adjacent to each other in the measuring direction.

[0043] In a preferred embodiment, the evaluation unit is configured to sample at least one, a plurality of or all of the receiver signals once or multiple times in order to determine the phase of the respective receiver signal. Multiple sampling can be performed in a single cycle and / or in multiple cycles for correspondingly determining the respective sampling values of the assigned receiver signal. The sampling time points are offset in phase with respect to the periodic receiver signal, for example by 90°. It is particularly advantageous if the sampling is performed at four sampling time points of the respective receiver signal, which are phase-shifted relative to each other so that four sampling values are provided. Preferably, the sampling is performed at regular phases or time intervals. If, for example, the first sampling time point t1 is offset in phase by a difference q from the zero crossing point of the periodic receiver signal, the additional sampling time points t(1+i) (where i=1, 2, 3, 4, ..., i max) can be offset relative to the zero crossing point by q+i*d+n*360° (where n=0, 1, 2, 3, ...), and where d is a defined phase offset, for example 90°, whereby it is particularly applicable: d=360° / (1+i max ).

[0044] In one embodiment, the sampling may be based on an IQ method.

[0045] Based on the sampled values of the receiver signal, a phase value can be determined by means of the evaluation unit, wherein the phase value characterizes the phase of the receiver signal. Based on these phase values, a phase signal can be formed which is taken into account when determining the absolute relative position.

[0046] If four sampling values E1, E2, E3 and E4 are determined for an assigned receiver signal, the phase value of the phase signal It can be determined as follows:

[0047] E 13 = E1-E3 (1)

[0048] E 24 = E2-E4 (2)

[0049] BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Advantageous embodiments of the invention are derived from the dependent claims, the description and the drawings. In the following, preferred embodiments of the invention are explained in detail based on the drawings. The drawings show:

[0051] Figure 1 is a schematic basic illustration of an exemplary measuring device equipped with a sensor device according to the invention,

[0052] Figure 2 is a basic circuit diagram of an embodiment of a sensor device,

[0053] Figure 3 and Figure 4 are in each case exemplary time-dependent developments of a transmitter signal, of a conductor strip loop current induced in the conductor strip loop of the sensor device due to this transmitter signal, and of a receiver signal,

[0054] Figure 5 is an exemplary schematic diagram of a scale element in two scale rows respectively having two modulation segments,

[0055] Figure 6 is an exemplary basic illustration of a phase signal over the entire absolute measuring range, which phase signal is determined in an evaluation unit of a sensor arrangement for determining an absolute relative position,

[0056] Figure 7 is a basic diagram of the phase difference of a phase signal,

[0057] Figure 8 is a basic illustration of a conductor strip loop of a sensor device in a modulation section,

[0058] Figure 9 is a basic diagram of a measuring coil used to determine the phase of a transmitter signal.

[0059] Figure 10 is a basic illustration of the arrangement of the components of the evaluation unit on the circuit board of the sensor device, and

[0060] Figure 11 is an exemplary phase trace showing the correlation of two phase signals with each other. DETAILED DESCRIPTION

[0061] Figure 1 An exemplary embodiment of a measuring device or measuring instrument 10 in the form of a caliper is shown. The measuring instrument 10 is configured as a digital measuring instrument. In this exemplary embodiment, the measuring instrument 10 is configured to measure distance or length measurements. For this measurement, the measuring instrument 10 includes an inductive sensor device 11 according to the present invention.

[0062] Inductive sensor device 11 includes a scale body 12 extending along a measuring direction M and a sensor unit 13 supported on scale body 12 movably along the measuring direction M. In an embodiment of measuring instrument 10 in the form of a caliper, measuring direction M is a linear direction. In other measuring instruments or applications, measuring direction M of inductive sensor device 11 may also extend in a curved manner, for example, along a circular arc. The functional principle of inductive sensor device 11 according to the present invention can also be applied to devices (e.g., measuring instruments) in which measuring direction M does not extend in a straight direction.

[0063] The scale body 12 includes a plurality of scale elements, which are configured as conductor strip loops 17. According to this example, the conductor strip loops 17 are arranged in multiple rows, in this case a first scale line 18 and a second scale line 19. Alternatively, a single scale line or more than two scale lines may be present. The scale lines 18, 19 extend parallel to one another along the measuring direction M. In a transverse direction Q, which is oriented orthogonally to the measuring direction M, the first scale line 18 and the second scale line 19 are offset from one another and, in particular, are arranged at a distance from one another.

[0064] The conductor strip loops 17 are arranged in a first scale row 18 having a first division d1. The conductor strip loops 17 are arranged in a second scale row 19 having a second division d2. The divisions d1 and d2 are of different sizes and form a vernier scale.

[0065] The conductor strip loops 17 are made of a conductive material such as copper, or at least contain a conductive material. The individual conductor strip loops 17 are electrically insulated from each other. The conductor strip loops 17 are constructed in a ring-shaped closed manner so that the conductor strip loop current IL can flow along the conductor strip loops 17 (see, for example, FIG. Figure 2 By means of a temporally or spatially varying magnetic field in one or more conductor strip loops 17 , a conductor strip loop current IL can be induced in the inductive sensor device 11 .

[0066] In this embodiment, all conductor strip loops 17 are arranged in a common plane, which is parallel to the measuring direction M and extends parallel to the transverse direction Q. The contours of the conductor strip loops 17 can be selected differently. In the embodiment shown here, each conductor strip loop 17 is formed by a conductor strip having two straight transverse legs 20, which are arranged at a distance from each other in the measuring direction M and extend in the transverse direction Q ( Figure 1 、 5 and 8). The two transverse legs 20 are connected by means of two longitudinal legs 21 of the conductor band loop 17 to form a closed loop. The two longitudinal legs 21 are arranged at a distance from one another in the transverse direction Q. In this embodiment, the longitudinal legs 21 are straight and extend in the measuring direction M. In a modified embodiment, the longitudinal legs 21 can also have a curved extension and, for example, can be semicircular.

[0067] The shape of the conductor band loop 17 is based on Figure 8 It is particularly evident there that each conductor strip loop 17 comprises a center line C which extends centrally along the conductor strip of each conductor strip loop. The section of the center line C extending along the transverse leg 20 serves as a reference for defining the first graduation d1 and the second graduation d2, as shown in FIG. Figure 8 As shown in .

[0068] The sensor unit 13 of the inductive sensor device 11 includes a transmitting coil 25 and at least one receiving coil, for example, a first receiving coil 26 and a second receiving coil 27 for each existing scale line, and thus, according to this example, a first receiving coil 26 and a second receiving coil 27 for each first scale line 18 and second scale line 19. The first receiving coil 26 and the second receiving coil 27 assigned to a common scale line 18 or 19 are offset relative to each other in the measuring direction M. For example, the receiving coils 26 and 27 can be implemented as a loop. The coil loop can be formed by two sinusoidally extending conductor strip sections that are offset relative to each other by half the wavelength of the graduation d1, d2 of the corresponding scale line 18 or 19. Due to the offset of the first receiving coil 26 relative to the second receiving coil 27, their receiver signals are out of phase with each other, for example, by 90°.

[0069] The transmitting coil 25 can surround the two receiving coils 26, 27 assigned to the same scale line 18 or 19 and can preferably at least approximately form an envelope around the receiving coils 26, 27. The transmitting coil 25 is formed in particular by a single transmitting coil loop or by a plurality of transmitting coil loops arranged in alignment in the measuring direction M and the transverse direction Q.

[0070] Thus, exactly one transmitting coil 25, exactly one first receiving coil 26 and exactly one second receiving coil 27 each form a common coil group 28 ( Figure 1 ). No additional transmitting and receiving coils are required. In this exemplary embodiment, exactly one coil group 28 of the sensor unit 13 is assigned to each scale line 18 , 19 . Figure 1 The coil assembly 28 is shown schematically in a highly simplified manner.

[0071] Figure 2 The circuit diagram of an embodiment of an inductive sensor device 11 is shown. Transmitter coils 25 are connected in series to one another in a circuit branch 29. Circuit branch 29 connects a first node 30 to a second node 31. In this example, circuit branch 29 is a two-terminal network. It can simply consist of a series connection of components.

[0072] By means of the transmitter circuit 32, a transmitter signal S can be provided to the transmitter coil 25. Figure 2As an alternative to the embodiment of FIG, a separate transmitter circuit can be provided for each transmitting coil. In this embodiment, the transmitter signal S is the transmitting coil current IS. The transmitting coil current IS has a non-constant time profile and can be, for example, a rectangular wave signal, a triangular signal, a sawtooth signal, a sinusoidal signal, or another time-varying signal. Transmitter circuit 32 includes a parallel oscillating circuit 33. An oscillating circuit capacitor 34 and an oscillating circuit inductor 35 are part of parallel oscillating circuit 33. The oscillating circuit capacitor 34 is arranged between the first node 30 and the second node 31. The oscillating circuit inductor 35 is connected in series with the transmitting coils in circuit branch 29. In this embodiment, the oscillating circuit inductor 35 connects the series connection of the transmitting coils 25 to the second node 31. With the aid of the oscillating circuit inductor 35 and the oscillating circuit capacitor 34, a suitable resonant frequency of the parallel oscillating circuit 33 can be set.

[0073] The oscillating circuit capacitance 34 may be implemented by one or more capacitors, for example, a plurality of capacitors connected in parallel. The oscillating circuit inductance 35 may be implemented by one or more coils or windings.

[0074] The first node 30 is connected to a supply DC voltage UDC. The supply DC voltage UDC can be provided by means of a battery in the mobile measuring instrument 10, for example Figure 1 As shown in . The second node 31 is connected to the ground potential GND via a series resistor 36 and a controlled switch 37. The controlled switch 37 has a control input 38. With the aid of a corresponding switching signal SW at the control input 38, the controlled switch 37 can be switched between a conducting state and a blocking state. In the conducting state, an electrical connection is established between the second node 31 and the ground potential GND, while this electrical connection is interrupted in the blocking state of the controlled switch 37. In particular, the controlled switch 37 can be a semiconductor switch, such as a bipolar transistor or a field-effect transistor. In this case, the base or gate of the corresponding transistor serves as the control input 38.

[0075] A transmitter control unit 39, which may be part of a control device 40, is used to control the controlled switch 37. According to this example, the controlled switch 37 is switched by means of a clocked switching signal SW having a clock frequency that corresponds approximately to the resonant frequency of the parallel oscillating circuit 33. If the controlled switch 37 is inductive, the oscillating circuit capacitance 34 is charged; if the controlled switch 37 is blocked, the oscillating circuit capacitance 34 is discharged via the circuit branch 29 and, therefore, via the transmitting coil 25. This generates a transmitter signal S or a transmitting coil current IS, which flows through the transmitting coil 25.

[0076] Due to the series connection in circuit branch 29, the transmitting coil current IS also flows through the oscillating circuit inductor 35. A measuring coil 41 is inductively coupled to this oscillating circuit inductor 35 or is a transformer-type coupled thereto. Measuring coil 41 generates a measurement signal whose phase corresponds to the phase of the transmitting coil current IS. Measuring coil 41 is electrically connected to an evaluation unit 42, which may be part of a control device 40. Measuring coil 41 provides the measurement signal to evaluation unit 42. Therefore, the phase of transmitting coil current IS is known in evaluation unit 42. Ideally, the phase of transmitting coil current IS is also determined by the control of controlled switch 37 and the dimensioning of parallel oscillating circuit 33. However, in practice, deviations may occur due to component tolerances, temperature variations, and / or other external influences. The optional presence of measuring coil 41 ensures that the phase of transmitting coil current IS is determined independently of these influences.

[0077] The receiving coils 26, 27 are connected to an evaluation unit 42 of the sensor device 11 and provide a receiver signal E generated by each receiving coil 26, 27 to the evaluation unit. In this exemplary embodiment, each receiving coil 26, 27 provides a receiving coil voltage UE as a receiver signal E to the evaluation unit 42. Since, according to this example, there are two coil groups 28, each having a first receiving coil 26 and a second receiving coil 27, four receiving coil voltages UE are provided to the evaluation unit 42, namely a first receiving coil voltage UE1, a second receiving coil voltage UE2, a third receiving coil voltage UE3, and a fourth receiving coil voltage UE4.

[0078] In this embodiment, the control device 40 is a conventional microcontroller. No application-specific components are required to realize the sensor device 11. As an alternative to this embodiment, the evaluation unit 42 and the transmitter control unit 39 can also be realized as separate components or component units.

[0079] The transmitter circuit 32, the receiving coils 26, 27 and the control device 40 can be arranged on a common carrier of the sensor unit 13, for example a circuit board 43 ( Figure 9 and Figure 10). The circuit board 43 is preferably a multilayer circuit board. For example, the oscillating circuit inductor 35 can be arranged on the top side 44 of the circuit board 43. The measuring coil 41 can be implemented by a conductor strip that forms a measuring loop 45 on the opposite side of the oscillating circuit inductor 35 on the top side 44. The measuring loop 45 is not completely closed in a ring-like manner, but rather includes a first end point 46 and a second end point 47, which are not directly electrically connected to each other, but only electrically connected via the other measuring loop. The first end point 46 and the second end point 47 of the measuring loop 45 are each electrically connected to each other. In the top view, the conductors connecting the measuring loops 45 cross each other twice, without being electrically connected at the intersection points (for example, the conductors extend in different layers of the circuit board 43). Therefore, the two measuring loops 45 have the shape of an "8", with a central loop 48 arranged between them. At the central loop 48, one of the measuring loops 45 is connected to the evaluation unit 42.

[0080] The ratio of the total area enclosed by the two measuring rings 45 relative to the area enclosed by the central ring 48 is a defined parameter. In particular, this ratio may be equal to 1 or may be greater than 1 (i.e. the total area enclosed by the two measuring rings 45 exceeds the area enclosed by the central ring 48). For example, the ratio may be weighted based on the influence of the oscillating circuit inductance 35 on the far field, wherein the inductance and its ferrite amplify the far field in the central ring 48. This results in a higher magnetic flux density than in at least one of the measuring rings 45. Due to the definition of this ratio as described above, the voltage induced by the magnetic field of the oscillating circuit inductance 35 is amplified and the voltage induced by the far field is weakened or ideally disappears. Due to this construction of the measuring coil 41, electromagnetic far fields are avoided from influencing the measurement. Please note that Figure 9 The rings 45 , 48 are not drawn to scale but are presented schematically only.

[0081] In accordance with Figure 2 In the circuit diagram of FIG. 4 , it is clear that a shield 49 may be provided between the oscillating circuit inductor 35 and the transmitting coil 25. This shield 49 serves in particular to protect the oscillating circuit inductor 35 and the measuring coil 41 from electromagnetic influences of the transmitting coil 25, the receiving coils 26, 27 or the conductor strip loop 17, in order to ensure an accurate determination of the phase of the transmitting coil current IS. For example, the shield 49 may be formed by a conductive layer in the circuit board 43 which is electrically connected to the ground potential GND ( Figure 10 ). The receiving coils 26, 27 and, as an option, additional components of the circuit may be arranged on respective opposite sides of a shield 49 (eg, in a layer of a circuit board), as shown. Figure 10 Schematically illustrated in FIG.

[0082] based on Figure 2As is also apparent from the circuit diagram in FIG, each conductor strip loop 17 can be illustrated as a closed current circuit, in which the inductive reactance XL and the ohmic resistance RL of the conductor strip loop 17 are connected in series. Due to the transmitter signal S or the transmitting coil current IS flowing through the transmitting coil, a conductor strip loop current IL is induced in the conductor strip loop 17 inductively coupled to the transmitting coil 25. The conductor strip loop current IL flows along the conductor strip loop 17 and thus flows through the inductive reactance XL and the ohmic resistance RL of the conductor strip loop 17. The impedance of the conductor strip loop 17 is And / or the apparent resistance Z can be calculated as follows:

[0083]

[0084] The inductive sensor device 11 described so far is configured to determine the absolute relative position xa between the sensor unit 13 and the scale body 12 in the measuring direction M, wherein the position variable in the measuring direction M is denoted by x ( Figure 1 、 Figure 6 and Figure 7 ).

[0085] Due to the transmitting coil current IS, a conductor loop current IL is induced in the plurality of conductor strip loops 17 in the first and second scale rows 18, 19, depending on the absolute relative position xa of the sensor unit 13 relative to the scale 12. The conductor loop current IL flowing through the conductor strip loops 17, in turn, induces a magnetic field, which in turn induces a receiving coil voltage UE in the receiving coils 26, 27 as a receiving coil signal E. If the sensor unit 13 moves along the scale 12 (the absolute relative position xa changes), the receiver signal in each receiving coil varies with a period corresponding to the graduation d1, d2 of the corresponding scale row 18 or 19. Therefore, the exact absolute relative position xa can be determined within one wavelength of the position variable x, which corresponds to the length of the period of the graduation d1 or d2.

[0086] By evaluating the receiver signals E of the two coil assemblies 28 based on different scale lines 18, 19 with different graduations d1, d2, a longer unambiguous range for determining the absolute relative position xa can be achieved based on the Vernier principle (nonius). However, in practice, this measuring range is not long enough, and additional measures are required to unambiguously determine the absolute relative position xa over a sufficiently long measuring path.

[0087] For this purpose, according to the invention, at least one of the scale rows, and in this example both the first scale row 18 and the second scale row 19, respectively, comprises one or more modulation sections xm, within which the apparent resistance Z or the impedance of the conductor strip loop 17 varies. For example, the apparent resistance Z and / or the impedance thus increases or decreases along the measuring direction M from one end of the modulation section xm to the other end of the modulation section xm. Within a modulation section xm, the apparent resistance Z and / or the impedance of all conductor strip loops 17 can have different magnitudes, so that the apparent resistance Z increases or decreases from one conductor strip loop 17 to an adjacent conductor strip loop 17 from one end of the modulation section xm to the opposite end of the modulation section xm.

[0088] Thus, the impedance in one, several or all existing modulation sections xm Or the change of the apparent resistance Z is preferably nonlinear. In other words, the impedance in the common modulation section xm Or the apparent resistance Z does not form a straight line. Instead, they can be points on a nonlinear curve Z(x). Therefore, the impedance Alternatively, the apparent resistance Z does not increase or decrease by the same difference between directly adjacent conductor strip loops 17 along the entire modulation segment xm. In particular, the ohmic resistance varies relative to the reactance. This enhances the determination of the absolute relative position xa and can, in particular, contribute to increased insensitivity to temperature deviations.

[0089] Impedance of each conductor loop The apparent resistance Z according to this example is also influenced by the ohmic resistance RL. In this embodiment, essentially only the ohmic resistance RL of the conductor loop 17 varies within the modulation section xm, while the inductive reactance XL remains essentially constant. The ratio of the inductive reactance XL to the ohmic resistance RL defines the phase shift of the conductor loop current IL of the corresponding conductor loop 17 relative to the transmitting coil current IS. Therefore, the phase shift between the transmitting coil current IS and the conductor loop current IL induced in the conductor loop 17 varies within the modulation section xm, depending on the relative position of the sensor unit 13 and the scale body 12 in the measuring direction M.

[0090] The phase offset between the transmitting coil current IS and the conductor loop current IL defines the phase position of the receiver signal E in the receiving coils 26 and 27 relative to the transmitting coil current IS and, in this example, the phase position of the receiving coil voltages UE (here: UE1, UE2, UE3, UE4) relative to the transmitting coil current IS. Since the phase of the transmitting coil current IS is known in the evaluation unit 42 (based on the measurement signal of the measuring coil 41), the phase position of one or more receiving coil voltages UE relative to the transmitting coil current IS can be determined. Based on the known correlation between the phase position and the relative position between the sensor unit 13 and the scale 12 in the measuring direction M (or along the axis of the position variable x), a coarse position determination of the relative position between the sensor unit 13 and the scale 12 in the measuring direction M (or along the axis of the position variable x) can be performed. Once the coarse position is known, a more precise relative position can be determined within the vernier scale or vernier length, and further within the first graduation d1 or the second graduation d2. Therefore, a phase modulation of the receiver signal E is performed in order to extend the measuring range, within which an unambiguous determination of the absolute relative position xa is possible, beyond a plurality of vernier scales or vernier lengths.

[0091] As an example, Figure 5 A segment of each scale line 18, 19 is schematically shown. In this exemplary embodiment, each scale line 18, 19 has at least one modulation segment xmi (i = a natural number) and optionally at least one non-modulation segment xci (i = a natural number). In each non-modulation segment xci, the impedance or apparent resistance Z of the conductor strip loop 17 does not change. Therefore, in these non-modulation segments xci, no phase modulation of the receiver signal E (in this example, the receive coil voltages UE1 to UE4) is performed.

[0092] exist Figure 6 , a first phase signal P1 based on the modulation of the first scale line 18 and a second phase signal P2 based on the modulation of the second scale line 19 are schematically illustrated as examples. In this embodiment, each scale line 18, 19 includes a plurality of modulation segments xmi, and according to this example, includes two modulation segments: the first scale line 18 has a first modulation segment xm1 and a second modulation segment xm2, and the second scale line 19 has a third modulation segment xm3 and a fourth modulation segment xm4.

[0093] The modulation segments xm1, xm2 or xm3, xm4 of a single scale row 18 or 19 do not directly adjoin one another, but are instead separated by a non-modulation segment xci. In this example, the first scale row 18 includes a first non-modulation segment xc1 and a second non-modulation segment xc2. The first modulation segment xm1 is positioned between these two non-modulation segments xc1 and xc2. The second modulation segment xm2 adjoins the second non-modulation segment xc2. For example, the second scale row 19 includes a third non-modulation segment xc3 and a fourth non-modulation segment xc4. The third non-modulation segment xc3 is positioned between the third modulation segment xm3 and the fourth modulation segment xm4, and the fourth non-modulation segment xc4 adjoins the fourth modulation segment xm4.

[0094] In this case, a first phase signal P1 is generated for the first scale line 18 as a function of the position variable x in the measuring direction M, and a second phase signal P2 is correspondingly generated for the second scale line 19 . Figure 6 Phase signals P1 , P2 as well as modulation sections xm1 to xm4 and non-modulation sections xc1 to xc4 are also schematically indicated in FIG.

[0095] In addition, Figure 6 , it is clear that in the measuring direction M, the non-modulated sections xc1, xc2 of the first scale line 18 do not overlap with the non-modulated sections xc3, xc4 of the second scale line 19. In this case, it is ensured that in each region of the scale lines 18, 19 in the measuring direction M (i.e. in the direction of the position variable x), phase modulation is performed in at least one scale line 18 or 19.

[0096] exist Figure 6 In the example shown in , the locus of the phase signals P1, P2 is a square. Alternatively, P1, P2 may be defined to provide other locus shapes, such as a circle or a diamond.

[0097] The amplitude of phase signals P1, P2 depends accordingly on the ratio of the magnitude of the inductive reactance XL to the magnitude of the ohmic resistance RL. If the magnitude of the ohmic resistance RL increases relative to the magnitude of the inductive reactance XL, the magnitude of the phase shift, and therefore the amplitude of the corresponding phase signals P1, P2, decreases. Therefore, by varying this ratio, the phase signals P1, P2 can be modified, and so to speak, modulated. In this embodiment, for this purpose, the ohmic resistance RL of the conductor strip loop 17 differs from one another in the respective modulation segments xm.

[0098] In this embodiment, the ohmic resistance RL of the conductor strip loop 17 is changed by changing the conductor strip cross section. In particular, the conductor strip thickness perpendicular to the plane of extension of the conductor strip loop 17 remains constant, and conversely, the respective conductor strip width b of the conductor strip loop 17 is increased or decreased compared to adjacent conductor strip loops 17. Figure 8 The variation of the conductor strip width b is schematically illustrated in FIG.

[0099] As an example, Figure 8 Three conductor strip loops 17 within the modulation section xm are shown. The conductor strip width b is determined perpendicularly to the direction of extension of the conductor strip, and in particular, perpendicularly to the inner and / or outer edges of the conductor strip. The conductor strip width b of each conductor strip loop 17 is constant. This means that in this embodiment, the transverse legs 20 and the longitudinal legs 21, which are part of the same conductor strip loop 17, have equal conductor strip widths b. According to this example, the conductor strip width b of the transverse legs 20 is measured in the measuring direction M, and the conductor strip width b of the longitudinal legs 21 is measured in the transverse direction Q.

[0100] Figure 8 The conductor strip width b is shown as an example and schematically only, increasing from conductor strip loop 17 to conductor strip loop 17 from left to right in the illustration. In the illustration, the left conductor strip loop 17 has a first conductor strip width b1, the center conductor strip loop 17 has a second conductor strip width b2, and the right conductor strip loop 17 has a third conductor strip width b3. Thus, the second conductor strip width b2 is greater than the first conductor strip width b1, and the third conductor strip width b3 is greater than the second conductor strip width b2. Obviously, the number of conductor strip loops 17 within the modulation section xm can be significantly greater than 3, and Figure 8 The illustrations in the should be regarded as schematic and basic illustrations only.

[0101] The minimum conductor strip width b is preferably 100 μm. The minimum distance between directly adjacent conductor strip loops 17 is preferably at least 100 μm. The minimum distance between two transverse legs 20 and between two longitudinal legs 21 of a common conductor strip loop 17 is preferably at least 100 μm.

[0102] In this embodiment, the conductor strip width b between the conductor strip loops 17 within the common modulation section xm is modified in such a way that the conductor strip width b increases or decreases inwardly and outwardly relative to the adjacent conductor strip loops 17 starting from the center line C. Therefore, for all conductor strip loops 17 within the common modulation section xm, the center line C has the same size and shape in the measuring direction M and the transverse direction Q. This in turn results in the loop height H and the loop width W of the conductor strip loop 17 also increasing with increasing conductor strip width b within the modulation section. Figure 8 In the example of , this means that the conductor strip loop 17 with the first conductor strip width b1 has a first loop height H1 and a first loop width W1. Similarly, the conductor strip loop 17 with the second conductor strip width b2 has a second loop height H2 and a second loop width W2, and the conductor strip loop 17 with the third conductor strip width b3 has a third loop height H3 and a third loop width W3.

[0103] As an example, Figure 3 and Figure 4 , the temporal progression of the transmitting coil current IS, the conductor strip loop current IL, and the receiving coil voltage UE are correspondingly illustrated in FIG. The phase offset between the transmitting coil current IS and the conductor strip loop current IL results from the impedance of the respective conductor strip loop 17, in particular from the apparent resistance Z. In a preferred embodiment, the phase offset between the receiving coil voltage UE and the conductor strip loop current IL is essentially independent of the electrical properties of the receiving coils 26, 27, since the receiving coils 26, 27 are connected to a relatively high impedance in the evaluation unit 42. Therefore, the phase position of the receiving coil voltage UE relative to the transmitting coil current IS characterizes the phase position of the conductor strip loop current IL relative to the transmitting coil current IS and can therefore be used to determine the phase signals P1, P2.

[0104] In the embodiment described herein, at least one of the receive coil voltages UE of each coil assembly 28 is sampled to generate corresponding phase signals P1, P2. For example, the first receive coil voltage UE1 may be used to determine the first phase signal P1, and the third receive coil voltage UE3 may be used to determine the second phase signal P2.

[0105] In this embodiment, continuous sampling of the receiving coil voltage UE (which can also be expressed as A / D conversion) is performed by means of the evaluation unit 42. Preferably, the receiving coil voltage UE is detected or sampled multiple times during each complete cycle, in this embodiment four times per cycle, i.e. at a first detection time t1, a second detection time t2, a third detection time t3 and a fourth detection time t4 within each cycle, as shown in FIG. Figure 3 and Figure 4 The detection is performed at regular time intervals, wherein the time interval between two directly subsequent detection points in time corresponds to a phase angle of 90° or a quarter of the period T. From the detected receiving coil voltages, the following voltage difference can be calculated by subtraction:

[0106] UE 13 = UE(t1)-UE(t3) (6)

[0107] UE 24 = UE(t2)-UE(t4) (7)

[0108] Based on these differences, the phase value can be calculated

[0109]

[0110] Therefore, the phase value Depending on the impedance or apparent resistance Z, which varies spatially within at least one modulation segment xm (according to this example, four modulation segments) along the measuring direction M, a first phase signal P1 of the first scale line 18 and a second phase signal P2 of the second scale line 19 are thus obtained. This in turn allows a rough assessment of the absolute relative position xa between the sensor units 13 and thus a relatively long measuring range.

[0111] For example, based on the first phase signal P1 and the second phase signal P2, a (rough) value of the absolute relative position xa can be assigned to the phase signals P1, P2 in a table or another assignment stored in the evaluation unit 42. The determined first and second phase signals P1, P2 may change due to external influences, for example due to changes in the ohmic resistance of the scale ring 17 due to temperature changes. The phase trajectory PT ( Figure 11 ) can have different shapes, as explained above. However, the points defining this phase trajectory cannot be precisely defined but may vary depending on external influences, for example due to temperature changes. However, it is possible to determine the average value of the first and second phase signals P1, P2 and / or to determine a range A of expected values along the phase trajectory PT. The progression of the phase trajectory PT can have a closed shape (e.g., a circle, a square, a diamond, etc.). A single, complete rotation around the phase trajectory PT corresponds to a measurement range with a clear (rough) position determination. However, it would also be possible to limit the measurement range to correspond to a continuous segment of the phase trajectory PT.

[0112] A table can be defined which characterizes the correlation of the first and second phase signals P1, P2. The table in particular only contains phase values which allow an unambiguous position determination. This means that coarse vernier ranges can be distinguished from one another. Figure 11 , ranges A of expected values that do not overlap with each other must be selected and used for the table. In this case, the ambiguity is eliminated.

[0113] Preferably, environmental influences (in particular temperature) which may lead to variations of the first and / or second phase signal P1, P2 can be determined and used as additional parameters (reflecting the temperature) in the table containing the values of the first and second phase signal P1, P2. Figure 11 In this case, the size of the range A can be reduced and thus a more reliable coarse position determination is possible.

[0114] Can be based on Figure 7 A modified embodiment of the present invention for determining the rough position of the sensor unit 13 relative to the scale body 12 will be explained. Figure 7The phase difference signal PD according to the position variable x is shown. The phase difference signal PD is formed by calculating the difference between the first phase signal P1 determined based on the first scale line 18 and the second phase signal P2 determined based on the second scale line 19. As a result, the two phase signals P1 and P2 can have the same Figure 6 . Preferably, the first phase signal P1 decreases continuously, while the second phase signal P2 increases continuously, or vice versa (e.g., with increasing position variable x), for determining the phase difference signal PD. This can be achieved, for example, by the following reason: the ohmic resistance RL of the conductor strip loops 17 of the first scale row 18 increases continuously, while the ohmic resistance RL of the conductor strip loops 17 of the second scale row 19 decreases continuously, or vice versa (e.g., with increasing position variable x).

[0115] In a preferred embodiment, segments xc1 and xm1 are used for the first phase signal P1, and segments xm4 and xc4 are used for the second phase signal P2. The resulting phase trajectory PT (trajectory) has two phase trajectory segments extending orthogonally to each other ("L" rotated 180 degrees). In each of these two phase trajectory segments, one of the phase signals P1 and P2 is constant, and the receiver signal is large, which provides good signal quality.

[0116] The present invention relates to an inductive sensor device 11, particularly for a measuring device or measuring instrument 10, preferably a mobile measuring instrument 10 operated by a battery. The inductive sensor device 11 has a scale 12 with a plurality of electrically conductive conductor loops 17. The conductor loops 17 are arranged in at least one scale row along a measuring direction M, preferably in a scale row 18 with a first graduation d1 and a second scale row 19 with a second graduation d2. A sensor unit 13 is arranged on the scale 12 so as to be movable along the measuring direction M. For each existing scale row 18, 19, the sensor unit 13 has a coil assembly 28, for example, comprising a transmitter coil 25 for generating a transmitter signal S and at least one receiver coil 26, 27. Each coil assembly 28 provides at least one receiver signal E to an evaluation unit 42 for determining the absolute relative position xa of the sensor unit 13 relative to the scale 12 in the measuring direction M. At least one of the existing scale lines 18, 19 has at least one modulation segment xm, within which the impedance of the conductor loop 17, in particular the apparent resistance Z, varies in the measuring direction M from one end of the modulation segment xm to the other end thereof. In particular, the apparent resistance Z increases or decreases, thereby modulating the phase position of the at least one receiver signal E relative to the transmitter signal S. This modulation is taken into account when determining the absolute relative position xa in the evaluation unit 42. For example, this allows for an increased measurement range within which the absolute relative position xa can be unambiguously determined. Furthermore, this position determination is robust to assembly tolerances.

[0117] List of reference numerals:

[0118] 10 Measuring instruments

[0119] 11 Sensor device

[0120] 12 scale body

[0121] 13 sensor unit

[0122] 17 Conductor Ring

[0123] 18 First scale line

[0124] 19 Second scale line

[0125] 20 Horizontal Leg

[0126] 21 longitudinal legs

[0127] 25 Transmitter Coil

[0128] 26 First receiving coil

[0129] 27 Second receiving coil

[0130] 28 coil sets

[0131] 29 circuit branches

[0132] 30 First Node

[0133] 31 Second Node

[0134] 32 Transmitter Circuit

[0135] 33 Parallel Oscillation Circuit

[0136] 34 Oscillation circuit capacitor

[0137] 35 Oscillation circuit inductance

[0138] 36 series resistor

[0139] 37 controlled switches

[0140] 38 Control Inputs

[0141] 39 Transmitter Control Unit

[0142] 40 Control Device

[0143] 41 Measuring coil

[0144] 42 evaluation units

[0145] 43 Circuit Board

[0146] 44 Top side of the circuit board

[0147] 45 Measuring ring

[0148] 46 First endpoint of the measuring loop

[0149] 47 Second end point of the measuring loop

[0150] 48 Center Ring

[0151] 49 Shield

[0152] A The range of expected values

[0153] b Conductor strip width

[0154] b1 Width of the first conductor strip

[0155] b2 Second conductor strip width

[0156] b3 Third conductor strip width

[0157] C Centerline

[0158] d1 first division

[0159] d2 second division

[0160] E Receiver signal

[0161] GND ground potential

[0162] H ring height

[0163] H1 Height of the first ring

[0164] H2 Height of the second ring

[0165] H3 Height of the third ring

[0166] IS Transmitting coil current

[0167] IL Conductor loop current

[0168] UE receiving coil voltage

[0169] UE1 first receiving coil voltage

[0170] UE2 Second receiving coil voltage

[0171] UE3 third receiving coil voltage

[0172] UE4 fourth receiving coil voltage

[0173] M Measuring direction

[0174] P1 first phase signal

[0175] P2 second phase signal

[0176] PD phase difference signal

[0177] PT phase trajectory

[0178] Q Horizontal direction

[0179] RL is the ohmic resistance of the conductor loop

[0180] S Transmitter signal

[0181] SW switch signal

[0182] T is the period of the receiving coil voltage

[0183] t time

[0184] t1 First detection time point

[0185] t2 Second detection time point

[0186] t3 The third detection time point

[0187] t4 fourth detection time point

[0188] UDC Power supply DC voltage

[0189] W Ring width

[0190] W1 first ring width

[0191] W2 Second ring width

[0192] W3 Third ring width

[0193] Position variable in the x-measuring direction

[0194] xc non-modulation section

[0195] xc1 first non-modulation section

[0196] xc2 Second non-modulation section

[0197] xc3 The third non-modulation section

[0198] xc4 fourth non-modulation section

[0199] xa absolute relative position

[0200] Inductive reactance of XL conductor with ring

[0201] xm modulation section

[0202] xm1 first modulation section

[0203] xm2 Second modulation section

[0204] xm3 third modulation section

[0205] xm4 fourth modulation section

[0206] Z is the apparent resistance of the conductor ring

Claims

1. An inductive sensor device (11), comprising: a scale body (12) having a plurality of electrically conductive conductor band loops (17) arranged in at least one scale row (18) with correspondingly defined graduations (d1, d2), wherein the at least one scale row (18, 19) extends parallel to the measuring direction (M), a sensor unit (13) which is arranged on the scale body (12) movably in a measuring direction (M) and comprises, for each scale row (18, 19), at least one transmitting coil (25), to which at least one transmitter signal (S) can be applied, and at least one receiving coil (26, 27) for providing a receiver signal (E) in each case, an evaluation unit (42) configured to evaluate the receiver signal (E) and to determine therefrom the absolute relative position (xa) between the sensor unit (13) and the scale body (12), Characterized in that the scale lines (18, 19) or at least one of the existing scale lines (18, 19) has a modulation section (xm) extending in the measuring direction (M), within which the conductor band loops (17) have impedances and / or apparent resistances (Z) that differ from one another, and the evaluation unit (42) is designed to take into account the modulation of the receiver signal (E) caused by the varying impedance and / or apparent resistance (Z) within the modulation section (xm).

2. The inductive sensor device according to claim 1, wherein The conductor band loops (17) are arranged in a first scale row (18) with a first graduation (d1) and in a second scale row (19) with a second graduation (d2), wherein the scale rows (18, 19) are arranged adjacent to each other in a transverse direction (Q).

3. The inductive sensor device according to claim 1 or 2, wherein: One receiving coil (26, 27) or two receiving coils (26, 27) are assigned to each scale line (18, 19).

4. The inductive sensor device according to claim 1 , wherein: All conductor strip loops (17) within the at least one modulation section (xm) have impedances and / or apparent resistances (Z) that are different from one another.

5. The inductive sensor device according to claim 1 , wherein: The impedance and / or apparent resistance (Z) of the conductor loops (17) in the modulation section (xm) differ from one another because the conductor loops (17) have different ratios of reactance (XL) to ohmic resistance (RL).

6. The inductive sensor device according to claim 1, wherein: The change in impedance and / or apparent resistance (Z) between adjacent conductor strip loops (17) along a measuring direction (M) within the at least one modulation section (xm) is nonlinear.

7. The inductive sensor device according to claim 1, wherein: A change in the impedance and / or apparent resistance (Z) between adjacent conductor loops (17) in the measuring direction (M) within the at least one modulation section (xm) is based solely or at least substantially on a change in the ohmic portion of the apparent resistance (Z).

8. The inductive sensor device according to claim 1, wherein: A plurality of or all conductor track loops (17) within the at least one modulation section (xm) have conductor track cross sections that differ from one another and, in particular, conductor track widths (b) that differ from one another.

9. The inductive sensor device according to claim 8, wherein: Each conductor strip loop comprises a loop height (H) in a transverse direction (Q) and a loop width (W) in a measuring direction (M), and wherein two conductor strip loops (17) with different conductor strip widths (b1, b2, b3) comprise loop heights (H1, H2, H3) of different sizes and loop widths (W1, W2, W3) of different sizes.

10. The inductive sensor device according to any one of the preceding claims, wherein Each conductor band loop (17) comprises two transverse legs (20) extending in a straight line in a transverse direction (Q).

11. The inductive sensor device according to claim 1, wherein: Each conductor band loop (17) comprises two longitudinal legs (21) extending in a straight line in the measuring direction (M).

12. An inductive sensor device according to any one of the preceding claims, wherein Each individual conductor strip loop (17) comprises a constant conductor strip width (b).

13. An inductive sensor device according to any one of the preceding claims, wherein The scale rows (18, 19) or at least one of the existing scale rows (18, 19) comprises a non-modulated section (xc) extending in the measuring direction (M), in which non-modulated section (xc) all conductor band loops (17) have equal impedance and / or equal apparent resistance (Z).

14. The inductive sensor device according to claim 13, wherein: All conductor strip loops (17) within the non-modulated section (xc) have an equal conductor strip cross section and, in particular, an equal conductor strip width (b).

15. The inductive sensor device according to claim 2 and claim 13 or 14, wherein: The first scale line (18) and the second scale line (19) each comprise at least one non-modulated section (xc), which are arranged in a non-overlapping manner along the measuring direction (M).

16. An inductive sensor device according to any one of the preceding claims, wherein The evaluation unit (42) is configured to determine a phase signal (P1, P2) from at least one of the receiver signals (E), wherein the phase signal (P1, P2) describes a phase offset between the transmitter signal (S) and a conductor strip loop current (IL) induced in one or more of the conductor strip loops (17) due to the transmitter signal (S).

17. An inductive sensor device according to any one of the preceding claims, wherein The evaluation unit (42) is designed to sample at least one of the receiver signals (E) a plurality of times and to determine a sampling value accordingly.

18. The inductive sensor device according to claims 16 and 17, wherein The evaluation unit (42) is designed to determine a phase value (φ) of the phase signal (P1, P2) from sampled values of the receiver signal (E).

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