Multi-track assembly for length- and angle-measuring systems

Abstract

The invention relates to a device for a length- or angle-measuring system, comprising: a first measuring track with a periodic coding that has a first number of division periods, said first measuring

Description

[0001] The invention relates to a multi-track assembly for measuring systems for position determination, a sensor head for scanning the multi-track assembly, and a corresponding measuring system composed of a multi-track assembly and a sensor head. BACKGROUND

[0002] Various measuring systems for position determination are known from the prior art, in particular Iinear / length measuring systems, angle-measuring systems, or rotary encoders. Linear measuring systems or length measuring systems are configured for determining the position along a route having different end points. In contrast, angel-measuring systems are configured for determining the position along a closed circular path. A measuring system for position determination comprises a scale standard which contains coded position information, and a scanning head having a sensor. Furthermore, the measuring system can comprise a physical evaluation channel and an evaluation circuit. Typically, the position information of the measuring system is forwarded via an interface to a servocontroller for control purposes (for example for controlling position, speed or torque).

[0003] The position measurement takes place by the relative movement of the scanning head and the scale standard. In the process, the sensor measures a physical property, for example a magnetic or electrical measured variable, which is dependent on the coded position information. An item of position information is then calculated from the change in the physical property, by the evaluation circuit. The obtained position information can either be relative, if it is dependent on a starting position, or absolute, if each point of a trajectory is clearly defined by the coded position information of the scale standard. Depending on the measuring system, the scanning head or the scale standard moves. In the case of a circular scale standard, reference is made to rotor and stator.

[0004] For absolute position measurement, what are referred to as Vernier-coded scale standards are known. The scale standard comprises at least two periodically coded measuring tracks, which have different division periods, such that for each position on the scale standard a unique signal combination of the tracks is present.

[0005] Known systems use for example coded measuring tracks, which are arranged in the same plane, in parallel with the scanning surface or with the scanning point of the sensor or the sensor elements. For example, the publication DE 10 2021 205036 A1 discloses a scanning element for a system comprising a plurality of tracks arranged in parallel in the same plane. The publication EP 2329225 B1 discloses an inductive position sensor for a system having a plurality of tracks that are led in parallel in the same plane. The publication EP 0845659 B1 discloses a scanning element for a position measuring means in which a plurality of tracks having different periodicities are arranged in parallel in the same plane.

[0006] Theoretically, such assemblies and systems can be expanded by any number of tracks, in order to increase the measuring accuracy. However, the parallel positioning of two or more Vernier channels in the same plane, as is known from the prior art, results in a series of disadvantages, which will be discussed briefly in the following.

[0007] With every additional parallel measuring track, the width of the assembly increases. In the case of an angle-measuring system, this means that either the inside diameter becomes smaller, which is in particular disadvantageous for systems which require a large through-hole, for example for wiring harnesses, or the outside diameter increases, which in turn leads to an increased space requirement. The disadvantage of an increased space requirement applies in the same way for linear measuring systems.

[0008] The different lengths of the division periods lead to different operating points of the individual sensor elements. The distance between the scale standard and sensor element, also referred to as the air gap, is defined as the operating point. Furthermore, the behavior of the generated signal amplitude of the sensor element is generally not linear.

[0009] The system resolution is essentially defined by the measuring track that has the largest number of division periods, i.e. the smallest division length. The higher the requirement with respect to the system resolution, the higher the number of division periods of said track generally has to be. However, a track having a plurality of division periods dramatically limits the operating region. The larger tracks generally serve for generating the absolute position of the system. However, it is the case that the greater the difference in the division periods of the individual tracks is, the greater the difference in their amplitude curve is.

[0010] For the configuration of the sensor, it is expedient to vary the number of division periods of the individual measuring tracks only minimally, or to define them in the same order of magnitude. In this way, the operating regions of the measuring tracks would not be mutually limiting, and the amplitude curves thereof would deviate only insignificantly from one another. In this case, however, care must be taken that as a result the requirement of accuracy of the measuring channels for determining the absolute position of the system becomes significantly stricter.

[0011] In summary, it can be found that, for a system having higher resolution, which corresponds to a track having a plurality of division periods, it is the case that the larger the result of the multiplication of the number of division periods of the measuring tracks is, the higher the demands that apply with respect to the position acquisition of the individual tracks. In addition, it is the case that the larger the difference of the number of division periods is, the greater the difference is with respect to the operating region of the individual sensor elements. This in turn limits the operating region of the overall system.

[0012] A further disadvantage of tracks of the scale standard configured in parallel in the same plane is the robustness of the system with respect to assembly errors. Assembly errors include in particular vertical tilting, horizontal twisting or horizontal offset of the scanning head or of the sensor and the sensor elements with respect to the tracks of the scale standard.

[0013] The wider a multi-track assembly is, the more significant the effect of tilting is on the operating region or the air gap of the sensor, in particular on the outermost track. These typically include those having the most division periods and thus those having the smallest operating region. The tilting results in a change in the relative phase between the sensor and the scale standard. If this phase error is greater than the maximally permitted error, the absolute position can no longer be correctly determined.

[0014] A horizontal rotation and a horizontal offset of the scanning head relative to the scale standard lead to a change in the relative phase between the position signals of the individual measuring channels and in turn reduces the operating region of the system. If, in combination with the accuracy of the track, the phase change is greater than the maximally permitted positioning error, the absolute position can no longer be correctly determined. It is also the case, here that the influence of the phase shift is more pronounced the wider the system, i.e. the more tracks it has.

[0015] The inventors have addressed the problem of providing a measuring system for position determination which overcomes the above disadvantages, in particular significantly reduces the influence of assembly errors (tilting, twisting, offset, eccentricity, etc.), and at the same time remains particularly compact. SUMMARY

[0016] The stated problem is solved by a device having the features of claim 1, a system having the features of claim 7, and a sensor head having the features of claim 18. Various embodiments and developments of the present invention are described in the dependent claims.

[0017] An assembly is described, which comprises: a first measuring track having a periodic coding which has a first number of division periods, wherein the first measuring track is arranged in a first plane, and at least one second measuring track having a periodic coding which has a second number of division periods, wherein the second measuring track is arranged in a second plane. The first number of division periods and the second number of division periods differ from one another. The first plane and the second plane are in parallel with one another, and the first measuring track and the second measuring track overlap at least in part.

[0018] A system is also described, which comprises: an assembly according to the above paragraph, and a sensor head having a first sensor element which, together with the first measuring track, forms a first measuring channel, and at least one second sensor element which, together with the second measuring track, forms a second measuring channel. The first and second sensor element cover at least one division period of the first and second measuring track, respectively.

[0019] Furthermore, a sensor head for an assembly as set out above is described, comprising the following: a first sensor element which is arranged in a third plane and is configured for forming a first measuring channel, together with the first measuring track; and at least one second sensor element which is arranged in a fourth plane and is configured or forming a second measuring channel, together with the second measuring track. The third plane and the fourth plane are in parallel with one another and spaced apart from one another, wherein the first sensor element and the second sensor element overlap at least in part.

[0020] This makes it possible in particular to create a configuration which minimizes the otherwise differing influence of errors in the configuration or assembly of the multi-track assembly on the respective measuring channels. Errors in the configuration or assembly include in particular tilting, twisting, offset, eccentricity of the measuring tracks and / or sensor elements. Furthermore, such an assembly results in the advantage that a phase error, which may occur, has the same geometric effect on all the measuring channels. Furthermore, such a configuration allows for a compact structure, in particular with respect to the ratio of the outside diameter to the inside diameter in the case of an angle-measuring system. It is likewise made possible to optimize the operating region and to scan the coded information of the measuring tracks in an improved manner. Furthermore, it is possible to reduce the complexity in production and in operation of a multi-track assembly. BRIEF DESCRIPTION OF THE FIGURES

[0021] For improved understanding of the features and advantages of the invention, some embodiments of the invention will be described in more detail in the following with reference to the accompanying Fig. 1 to 19. However, the illustrations of the figures show only some embodiments and are not to be considered limiting, since other, equally effective, embodiments may also exist. It is noted that some of the details and / or features shown in the figures are not reproduced true to scale, for reasons of clarity.

[0022] Fig. 1 is a block diagram of a position measuring system.

[0023] Fig. 2 is a perspective view of a length measuring system according to the prior art.

[0024] Fig. 3 is a perspective view of an angle-measuring system according to the prior art.

[0025] Fig. 4 is a perspective view of a length measuring system comprising a periodically coded scale standard and a periodic sensor element.

[0026] Fig. 5 shows two views from above of an embodiment of a Vernier assembly comprising two parallel tracks having 16 and 3 division periods, respectively, wherein the sensor covers only part of the scale standard (Fig. 5a) or covers the entire surface of the scale standard (Fig. 5b).

[0027] Fig. 6 shows the output signals of a sensor element of a track having 16 division periods, depending on the angle.

[0028] Fig. 7 shows the output signals of a sensor element of a track having 3 division periods, depending on the angle.

[0029] Fig. 8 shows the starting position of the sensor elements compared with the absolute position of the measuring system depending on the angle.

[0030] Fig. 9 is a side view of an embodiment of a scale standard for a linear Vernier coding having 3 tracks.

[0031] Fig. 10 is a graph showing the signal amplitude of an inductive sensor depending on the air gap or operating region for different division lengths.

[0032] Fig. 11 shows views from above of two embodiments of a scale standard for a Vernier coding having two tracks each having different division periods.

[0033] Fig. 12 is a cross-sectional view of a measuring system having an assembly error in the form of tilting.

[0034] Fig. 13 is a view from above of a measuring system having an assembly error in the form of twisting.

[0035] Fig. 14 is a view from above of two overlapping Vernier tracks of a scale standard having 16 and 3 division periods, respectively.

[0036] Fig. 15 is a schematic cross-sectional view of an embodiment of a measuring system comprising two overlapping measuring channels.

[0037] Fig. 16 is a perspective view of a measuring system comprising two parallel Vernier measuring channels in the same plane (Fig. 16a), and of a measuring system having overlapping Vernier measuring channels in different planes (Fig. 16b).

[0038] Fig. 17 is a simplified perspective view of an embodiment of an anglemeasuring system comprising three completely overlapping measuring channels.

[0039] Fig. 18 is a graph showing the signal amplitude of three measuring tracks having 32, 8 and 3 division periods depending on the air gap.

[0040] Fig. 19 shows views from above of a scale standard for an angle-measuring system having (1) a magnetic track, (b) a geometric track, and (c) a combination of a magnetic and a geometric track.

[0041] DETAILED DESCRIPTION

[0042] The following definitions apply for the description of the drawings.

[0043] A scale standard comprises one or more measuring tracks. A measuring track comprises periodically or aperiodically coded information, which can be introduced in a wide variety of forms. In this case, a scale standard or a measuring track of a scale standard can be configured both as a passive and as an active element. The scale standard or the one or more measuring tracks of a scale standard can be scanned by a scanning head or a sensor.

[0044] A multi-track assembly refers to a scale standard which comprises two or more measuring tracks.

[0045] In the case of periodic coding of a measuring track of a scale standard, a division period refers to the period of the coding, i.e. the smallest unit or distance of the coded measuring track according to which the coded information repeats.

[0046] A scanning head comprises a sensor which can comprise one or more sensor elements. A sensor can be based on one or more physical measuring principles, in particular magnetic, inductive, optical, capacitive measuring principles, and / or giant magnetoimpedance (GMI) as a measuring principle. A sensor can scan the entire length or surface or a scale standard as well as only a part or a segment of a scale standard. A sensor element covers at least one division period of the measuring track. During scanning, the sensor generates one or more analogue signals which are influenced by the coded information which the scale standard or the one or more measuring tracks comprise.

[0047] In particular, a sensor or a sensor element can comprise an emitter coil and a receiver. An emitter coil can emit an electromagnetic emitter signal having a predefined emitter signal frequency, which can induce a signal in the receiver coil. Depending on the conductivity or permeability of a region of the measuring track to be scanned, the induced signal is amplified or reduced. The signal amplitude, which refers to the amplitude of the induced sensor signal, depends in particular on the operating region or operating point of the sensor or sensor element.

[0048] A measuring channel refers to the combination of a measuring track of a scale standard with a sensor element associated with the measuring track, which is arranged in a manner suitable for scanning the measuring track, for position determination, completely or in part.

[0049] A physical evaluation channel refers to a physical channel via which the one or more analogue signals generated during scanning are forwarded to an evaluation electronics.

[0050] An evaluation electronics converts analogue sensor signals, by suitable methods, into digital or analogue position information, and can in particular comprise a switching circuit, controller or microcontroller.

[0051] Overlapping of measuring tracks refers to the geometric overlapping of the measuring tracks in the direction of the sensor scanning them or the sensor elements scanning them. Overlapping of sensor elements refers to the geometric overlapping of the sensor elements in the direction of the measuring tracks scanned thereby.

[0052] In the case of a multi-track assembly for a linear or length measuring system, fully or completely overlapping means that the edges of the smallest squares in each case, which in each case comprise one of two adjacently overlapping measuring tracks or one of two adjacently overlapping sensor elements orthogonally to the overlap direction, are substantially, i.e. over at least 95% of the surface enclosed by them in each case, congruent in the overlap direction.

[0053] In the case of a multi-track assembly for an angle-measuring system, fully or completely overlapping means that the rings or partial rings, which are formed of the respectively largest inner complete or partial circle or the inner complete or partial ellipse and the respectively smallest outer complete or partial circle or outer complete or partial ellipse, which in each case delimit one of two adjacently overlapping measuring tracks or one of two adjacently overlapping sensor elements orthogonally to the overlap direction, are substantially, i.e. over at least 95% of the surface located between their inner and outer boundary in each case, congruent in the overlap direction.

[0054] In contrast, a partial overlap exists if a track does not extend over the entire angle or over the entire length of the other track(s), such that the overlap is less than 95%, or if for example in an assembly having four tracks, in each case two completely overlapping tracks can be configured in parallel.

[0055] A mechanical change refers to a change, in particular change in the shape, surface and / or structure of an object, by the action of a force. Geometric modulation refers to the change in the shape of an object by the action of a force.

[0056] Magnetic measured variables include for example the field strength, the flux density, the reluctance, the permeability, the saturation magnetization, the dipole moment, and the polarization.

[0057] Electrical measured variables include for example the current, the voltage, the charge, the capacitance, the energy, the power, the resistance, and the conductivity.

[0058] Fig. 1 is a general block diagram of a position measuring system, in the present case a length measuring system. The measuring system comprises a scale standard 1 and a scanning head 2 (sensor head). The position information of the measuring system is forwarded via an interface 4 to a servocontroller 3 for regulating for example the position, the speed and / or the torque, or for control.

[0059] The scale standard 1 contains coded information, which can be introduced in a wide variety of forms. In this case, the scale standard 1 can be configured both as a passive and as an active element. Examples of active elements for the scale standard are angular position sensors (resolvers) and rotary encoders, which have a meandering structure which is supplied with an alternating current signal.

[0060] The scanning head 2 comprises a sensor 2.1. The sensor 2.1 can be based on various physical measuring principles, for example on a magnetic, inductive, optical, capacitive, or the “giant magnetic impedance” (GMI) measuring principle. In this case, the sensor 2.1 can scan (acquire) the entire length or surface or the scale standard 1 or also only a part or a segment thereof. During scanning, the sensor 2.1 generates one or more analogue signals.

[0061] The scanning head 2 furthermore comprises an electronics circuit having evaluation electronics 2.2 (sensor circuit), which converts the analogue sensor signals, by suitable methods, into digital or analogue position information. The sensor circuit 2.2 can comprise an evaluation circuit having a multiplexer, wherein the multiplexer is connected to the sensor elements and is configured to provide measuring signals via a single physical evaluation channel.

[0062] The position measuring system can be a linear measuring system or a length measuring system. Fig. 2 shows a linear or length measuring system. The scale standard 1 is configured as a linear, strip-shaped element which extends along a length direction x which also represents the measuring direction. It has a linear coding which also extends in the measuring direction x. The sensor head 2 is arranged above the scale standard 1 and can move along the measuring direction x in order to detect the scale standard 1.

[0063] Fig. 3, in contrast, shows an angle-measuring system having an annular scale standard 1 and a corresponding, also annular, sensor head 2. The scale standard 1 has a circular coding along a radial direction, which corresponds to the measuring direction. In the example shown, the sensor head 2 is arranged in parallel with and spaced apart from the scale standard 1. Furthermore, both elements have the same axis, which is arranged perpendicularly to the planes in which the scale standard 1 and the sensor head 2 each extend and which passes through a center of the scale standard or of the sensor head. During measuring, the sensor head can rotate about the axial axis and thus serve as the rotor, while the scale standard remains fixed and serves as the stator. Alternatively, the scale standard can rotate about the axis and the sensor head can remain fixed.

[0064] Typically, the scale standard 1 and the sensor head 2 are spaced apart by a substantially constant distance in a direction that extends perpendicularly to the plane in which the scale standard 1 extends, as shown in Fig. 1 to 3. Thus, both optical and also magnetic, capacitive or inductive measurements can be carried out.

[0065] Fig. 4 is a schematic view of a linear measuring system according to the prior art, which is based on an inductive measuring principle. In this case, the coded information is introduced into the scale standard 1 (standard) through different regions having different permeabilities p (reluctances) and / or different conductivities o. In the example shown, the linear scale standard 1 extends along a measuring direction x, wherein two adjacent regions in the measuring direction have a different permeability or conductivity. The coding is periodic, wherein a period has a sequence of a first region having a permeability po or conductivity oo, and a second region having a permeability pi or conductivity 01, and a division period X. An incremental position measurement proceeding from a starting position of the sensor head can be carried out by relative movement of the scale standard 1 and a sensor head.

[0066] In principle, the scale standard 1 comprises one or more periodically or aperiodically coded measuring tracks. In the case of periodic coding, the division period A corresponds to one period of the coding. The scale standard 1 is scanned (sensed) by a sensor 2.1. Thus, the scanning is not sampling, but rather a detection of the scale standard. It is the case that the sensor 2.1 contains a sensor element 2.1.1 for each track of the scale standard. A sensor element 2.1.1 is formed of at least one emitter coil 2.1.1.1 and one or more receiver coils 2.1.1.2. It is the case that a sensor element 2.1.1 can have one or more emitter coils 2.1.1.1 and an emitter coil 2.1.1.1 can be used both by just one sensor element 2.1.1 and by a plurality of sensor elements 2.1.1 together.

[0067] The sensor element 2.1.1 covers at least one division period A of the measuring track. The sensor element can also cover a plurality of division periods n A (where n g N), wherein n denotes the number of division periods. Thus, possibly occurring errors can be averaged, which reduces the general measuring error. The emitter coils 2.1.1.1 and the receiver coils 2.1.1.2 can for example be implemented as conductor tracks in the form of a meandering structure (pancake coils) in or on a rigid or flexible substrate (e.g. a printed circuit board). In the example shown, the sensor element 2.1.1 comprises a single emitter coil 2.1.1.1 which has the form of a cuboid, and two meander-shaped, offset receiver coils 2.1.1.2 which are arranged within the emitter coil 2.1.1.1.

[0068] A measuring track of the scale standard 1 in combination with the sensor element 2.1.1 forms a measuring channel. The electronic circuit 2.2 feeds an alternating current into the emitter coil(s) 2.1.1.1 of the sensor element 2.1.1, for example at a frequency in the range of a few kHz to 100 MHz. Owing to the inductive coupling (mutual induction) between the emitter 2.1.1.1 and receiver coils 2.1.1.2, an alternating current of the same frequency is induced in the receiver coils 2.1.1.2. In this case, the mutual induction is modulated in the case of a relative movement of the scale standard 1 with respect to the scanning head 2 (the sensor structure).

[0069] In the case of different permeabilities p, those regions of the scale standard 1 having higher magnetic permeability (pi >po) will amplify the mutual induction or the alternating current induced in the receiver coils 2.1.1.2.

[0070] In the case of different conductivities o, those regions of the scale standard 1 having higher conductivity (01 >uo) will reduce the mutual induction or the alternating current induced in the receiver coils 2.1.1.2.

[0071] The alternating currents induced in the receiver coils 2.1.1.2 or the measured signals are demodulated by the evaluation electronics 2.2 and converted into position information. The position information thus obtained is forwarded via an interface 4 to a servocontroller 3 for various control purposes. In one example, the interface is a synchronous serial interface (SSI) and comprises a power amplifier (line driver), e.g. of the type RS485, as well as a cable and a connector.

[0072] As described above, for position measuring the sensor head can move along the measuring direction above the surface of the scale standard, and in the process detect changes of one or more physical variables, such as the inductance or the magnetic field strength, wherein the evaluation circuit calculates position information from the sensor signals. Alternatively, the sensor head can be fixed, while the scale standard itself moves, for example rotates.

[0073] A distinction is made between incremental and absolute measuring systems.

[0074] The position information of an incremental measuring system contains only information relating to the relative offset with respect to the starting position “0” when the system starts. An extension can contain a defined system zero point in the form of a reference mark (reference index Ri or reference mark Rm). However, this information is available only when the sensor scans these corresponding marks on the scale standard, after activation.

[0075] The position information of an absolute measuring system contains the absolute offset between the scanning head and the scale standard immediately after activation. There are various possibilities for coding and detecting an absolute position.

[0076] For example, the scale standard can be coded by means of a pseudo random code (PRC). A PRC is a digital code (coded with N bits). In this case, the scale standard typically comprises just one measuring track to be scanned. In this case, a corresponding sensor detects a particular length or segment of said track. In this case, every detected partial surface of the coding, which corresponds to a combination of “ones” and “zeros”, may appear exactly once over the entire length or the entire angle. As a result, an absolute position can be obtained using corresponding evaluation electronics.

[0077] The implementation by means of pseudo random code (PRC) is particularly suitable for long measuring distances, but requires very complicated sensor structures and evaluation electronics, in order to decode the plurality of the code (N bits). Advantages of implementation by means of PRC can be considered to be the fact that theoretically and mathematically any desired system length can be coded and thus made possible. Furthermore, only one measuring track is required. Disadvantages can be considered to be the fact that a complex sensor structure and evaluation electronics are required, and this complexity increases with the measuring length.

[0078] Alternatively, the scale standard can be configured as a Vernier-coded scale standard. In this case, the scale standard comprises two or more periodically coded tracks, having different periodicities or division periods, which are also referred to as incremental tracks. In general, these tracks are guided in parallel with the scanning surface or the scanning point. A division period is the smallest unit of the coded scale standard, and in this case specifies the distance after which the coded pattern repeats.

[0079] Here, it is the case that the greatest common divisor (GCD) of the number of division periods of at least two measuring tracks of a Vernier-coded scale standard, which are consulted for obtaining the absolute position, must be equal to 1. This ensures that each combination of the measuring tracks within the scanning regions of the sensor exists only once over the entire scale standard, in particular length and / or angle, of a corresponding sensor. Thus, again, an absolute position can be obtained using corresponding evaluation electronics.

[0080] For a Vernier embodiment, a comparatively simple sensor structure and evaluation electronics is required, but the measuring length is limited. Therefore, this embodiment is particularly well suited for angle measurements, because in the case of these the maximum length, the arc length, is predefined. The fundamentally very compact physical implementation can be considered a further advantage. The maximum length, which is often limited in practice, can be considered a disadvantage. A further disadvantage can be considered the fact that a compromise between measuring length and accuracy is often required. The higher the accuracy requirements in the case of long stretches, the more complex a Vernier implementation becomes.

[0081] A simplified, absolute Vernier-coded angle-measuring system comprising a multi-track assembly is shown schematically in Fig. 5. The system is composed as follows.

[0082] The scale standard 1 consists of two parallel (or concentric) tracks 1.1 and 1.2 having different division periods in an XY plane. In the example of Fig. 5, the first track 1.1 contains sixteen division periods Ai (number of the division periods of the first track m = 16), and the second track 1.2 contains three division periods A2 (number of the division periods of the second track n2 = 3). In this case, the condition GCD (m, n2) = 1 is fulfilled (GCD = greatest common divisor). The sensor 2.1 consists of two sensor elements 2.1.1 and 2.1.2 arranged side-by-side (and above the associated tracks), which each have the same division periods as the associated tracks 1.1 and 1.2, respectively, also in theXY plane. In this case, the sensor 2.1 can cover both only a part of the scale standard 1, as shown in Fig. 5a, and the entire surface, as shown in Fig. 5b.

[0083] This principle can be expanded by any number of measuring tracks and the associated sensor elements, in that additional tracks, which are also parallel and concentric, are added. For the sake of simplicity and for clear illustration, in the example of Fig. 5 a system having just two tracks is shown.

[0084] In Fig. 6 and Fig. 7, the respective output signals of the sensor elements 2.1.1 and 2.1.2 of Fig. 5 are shown by way of example. Fig. 6 shows the output signal of the sensor element 2.1.1, and Fig. 7 shows that of the sensor element 2.1.2. In this case, in this example the two sensor elements 2.1.1 and 2.1.2 each generate two sinusoidal signals, which are offset by 90° relative to one another, i.e. a sine and a cosine signal. For a complete rotation of the scale standard 1 about 360° the sensor element 2.1.1 generates sixteen sine and cosine periods, which correspond to the number of division periods of the first track 1.1. According to the division periods of the track 1.2, the sensor element 2.1.2 generates three sine and cosine periods.

[0085] All the output signals generated by the sensor elements 2.1.1 und 2.1.2 pass through an evaluation electronics or circuit 2.2. Position information, in particular angle and length information, is obtained from the output signals by various mathematical operations (e.g. demodulation). The absolute position is determined by combining the position information generated on the output signals of the sensor elements 2.1.1 and 2.1.2. This is shown in Fig. 8. The absolute position is specified in Fig. 8 in radians (in the interval ±tt rad corresponds to ±180°). On account of the uniqueness of the pairs of the starting positions of the sensor element 2.1.1, shown as a solid line, and the starting position of the sensor element 2.1.2, shown as a dashed line, the absolute position, which is shown as a dot-dash line, is obtained over the entire mechanical position of 360°.

[0086] An example for a linear Vernier coding having three parallel tracks is shown in Fig. 9. Fig. 9 is a schematic view of a scale standard of an absolute length measuring system. The scale standard comprises three periodic measuring tracks 1.1, 1.2 and 1.3 having a periodicity Ao, Ai and A2, respectively, and a long a measuring direction x. The measuring tracks 1.1, 1.2 and 1.3 are arranged in parallel with one another and side-by-side in a direction that extends perpendicularly to the measuring direction. The lengths Ao, Ai and A2 of the divisions are different and the number of division periods m, n2 and ns of the tracks is also different, for the same length. The measuring track 1.1 of the scale standard 1 has m = 7, the measuring track 1.2 02 = 5, and the measuring track 1.3 has ns = 3 division periods. Here, the following relationship applies between the period length and the number of division periods of the respective measuring track: Ai= 1 / ni, wherein 1 stands for the total length of the scale standard.

[0087] The relationship GCD (ni, nj, nk, ...) = 1 (the indices i, j, k denote the tracks) must apply only for each of the tracks that are consulted for obtaining the absolute position. Typically, for this purpose, those measuring tracks are used which have the smallest number of division periods. In the example of Fig. 9, the three tracks fulfil the condition GCD (m, n2, ns) = 1. The coding is therefore unique.

[0088] Fig. 10 is a graph showing the signal amplitude (in volts) of an inductive sensor depending on the air gap (in millimeters) for different division lengths A = 0.25; 0.5; 1; 2; and 4 mm. The air gap is the distance between the scale standard and the sensor element in a direction which is perpendicular to the measuring direction and to the plane of the scale standard. It is also referred to as the operating point. It is desirable for the signals from the different tracks to have a sufficient amplitude in order to minimize measuring errors as far as possible. However, it is clear from Fig. 10 that the different lengths of the division periods lead to different operating points, and that the behavior of the generated signal amplitude of the sensor element is nonlinear. Furthermore, the system resolution is essentially defined by the measuring track that has the largest number of division periods, i.e. the smallest division length. However, as can be seen in Fig. 7, a track having a plurality of division periods, for example a track having the division length A = 0.25 mm, dramatically limits the operating region. It can furthermore be seen that the greater the difference in the division periods of the individual tracks is, the greater the difference in their amplitude curve is.

[0089] For the configuration of the sensor, it is therefore expedient to vary the number of division periods of the individual measuring tracks only minimally, or to define them in the same order of magnitude. In this way, the operating regions of the measuring tracks would not be mutually limiting, and the amplitude curves thereof would deviate only insignificantly from one another. In this case, however, care must be taken that the requirement of accuracy of the individual measuring channels for determining the absolute position of the system becomes significantly stricter.

[0090] This is visible in Fig. 11, which shows to examples of a scale standard for an angle-measuring system. The system in Fig. 11a has two measuring channels, one having a first measuring track 1.1 that has a partial length Ai = 360716, and having a corresponding sensor element, and one having a second measuring track, which has a second partial length A2 = 360715 and having the associated sensor element. The maximally permitted error e for the first measuring channel relative to the second measuring channel over an entire rotation of 360° is calculated as follows: e = angle / ( Ai ■ A2) = 3607(16 • 15) = 1.50° (1)

[0091] If both measuring channels exceed this error, the measuring system can no longer generate a unique, and thus valid, absolute position with this Vernier coding. In comparison with this, of. the system in Fig. 10b. This has a first measuring track 1.1 having a division length Ai = 360° / 16 and a second measuring track 1.2 having a division length A2 = 36073. The maximally permitted error is calculated analogously to above for e = 360° I (16-3) = 7.50°. In this case, the permitted error range is substantially greater, but there is the disadvantage that the operating points of the individual sensor elements differ more significantly.

[0092] It is therefore clear that for a high-resolution system, which comprises at least one track having a high number of division periods, the requirements with respect to the position detection of the individual tracks are particularly high. Furthermore, a large difference in the number of division periods between the different tracks leads to a correspondingly large difference with respect to the operating region of the individual sensor elements, which in turn limits the operating region of the overall system (air gap).

[0093] A further point to be considered is the robustness of the system with respect to assembly errors. Fig. 12 is a schematic view of an angle-measuring system having an assembly error in the form of tilting. Specifically the sensor head 2, which should ideally be arranged in parallel with the scale standard 2, is inclined with respect to the scale standard 1 by an angle alpha with respect to an axis A, which extends perpendicularly to the plane of the scale standard 1.

[0094] It can be seen that the larger or wider a system is, the more significant the effect of tilting is on the operating region (= air gap) of the sensor. In this case, the outermost track (+ / - dz), typically that having the most division periods and thus that having the smallest operating region, is influenced the most. The tilting results in a change in the relative phase between the sensor and the scale standard. If this phase error is greater than the maximally permitted error, the absolute position can no longer be correctly determined.

[0095] Further forms of assembly errors are an offset and twisting of the scanning head 2 or the sensor element with respect to the scale standard. Fig. 13 shows a length measuring system comprising three measuring channels which has such an assembly error. The sensor head 2 (and thus also the sensor elements contained therein) is ideally arranged such that its edges are arranged in parallel with the edges of the scale standard. In the example of Fig. 13, however, these edges are arranged about an angle alpha relative to an axis A which extends in parallel with an edge of the scale standard, and thus with respect to the scale standard 1 itself.

[0096] A rotation or an offset of the scanning head 2 relative to the scale standard 1 leads to a change in the relative phase between the position signals of the individual measuring channels and in turn reduces the operating region of the system. If the phase change is greater than the maximally permitted positioning error (in combination with the accuracy of the track itself), the absolute position can no longer be correctly determined. It is again the case that the influence of the phase shift is more pronounced the wider the system, (i.e. the more tracks it has).

[0097] Fig. 14 is a view from above of a first and a second scale standard for an angle-measuring system having a single, circular measuring track having 16 or 3 division periods (Fig. 14, left and center, respectively), and having the third scale standard which, by complete overlapping of the first and the second scale standards 1.1 and 1.2, forms a device having two overlapping measuring tracks. Since the greatest common divisor of the number of said tracks is equal to 1, it is also a Vernier assembly, which can be used for absolute position measurement. In contrast to the assemblies of Fig. 5 and 11, the measuring tracks are not arranged side-by-side in the same plane, but rather are arranged in an overlapping manner in different planes. Thus, the measuring tracks are congruent and have the same dimensions in the respective plane. In a further example, the measuring tracks overlap only in part.

[0098] Analogously, the corresponding sensor elements 2.1.1 and 2.1.2 are also overlapped. A schematic sectional view of an angle-measuring system having overlapping measuring channels is shown in Fig. 15. The measuring track assemblies 1.1 and 1.2 correspond to the measuring track assemblies of Fig. 14. The first measuring channel comprises the sensor element 2.1.1 and the measuring track 1.1. The second measuring channel comprises the sensor element 2.1.2 and the measuring track 1.2. Both the measuring track assemblies 1.1 and 1.2 and the sensor elements 2.1.1 and 2.1.2 are arranged one above the other in a direction z which extends perpendicularly to the plane xy. The first measuring channel, which comprises the measuring track 1.1 having the larger number of division periods, is thus arranged between the sensor element 2.1.2 and the measuring track assembly 1.2 having the smaller number of division periods. The scale standards and the sensor elements are in each case arranged in a plane which is in parallel with the plane xy. In the z-direction, the overlapping scale standards on the one hand and the sensor elements on the other hand are spaced apart by a distance z. In a further example, the sensor elements overlap only in part.

[0099] Fig. 16 is a perspective view of an angle-measuring system comprising two concentric, parallel Vernier measuring channels in the same z-plane (Fig. 16a), and of an angle-measuring system having overlapping Vernier measuring channels in different planes (Fig. 16b). For the sake of simplicity and for a clear illustration, the sensor elements 2.1.1 and 2.1.2 in Fig. 16, and also in Fig. 17, are shown only having the respective receiver coils of the sensor elements. In contrast, the emitter coils are not shown. As shown, the receiver coils are configured as sinusoidal conductor tracks. The number of periods of a receiver coil corresponds to the number of periods of the corresponding measuring track. It is again the case that the systems can be extended by any number of measuring channels. The emitter coils and / or the receiver coils of the different measuring channels can be arranged on the same substrate.

[0100] In the embodiments of Fig. 14-16, both the measuring tracks and the sensor elements are arranged not in parallel but rather either completely or partially overlapping. An axial overlap (z-direction) of two or more measuring channels both in the rotor (measuring track) and in the stator (sensor elements) makes it possible to provide a configuration which can significantly reduce the above-described disadvantages of a Vernier coding comprising measuring tracks arranged side-by-side. In particular, the entire system is substantially more compact, and the influence of assembly errors (tilting, twisting, offset, eccentricity, etc.) can be significantly reduced. A significant advantage of this assembly is also that a phase error, which may occur, has the same geometric effect on all the measuring channels. Furthermore, as described below, the operating region of the measuring tracks can be optimized in a simple manner. The outlay for producing and operating the measuring system can also be reduced. Although Fig. 14-16 show angle-measuring systems, it is clear that the overlapping of measuring channels can also be implemented, with the same advantages, in length measuring systems.

[0101] Fig. 17 is a perspective view of an angle-measuring system comprising three completely overlapping measuring channels, and thus an extension of the solution from Fig. 14-16 by one measuring channel. The system comprises a sensor and a scale standard. The sensor comprises a first sensor element 2.1.1 having a number m = 32 of division periods and a division period Ai = 360° / 32, a second sensor element 2.1.2 having a number n2 = 8 of division periods and a division period A2 = 36078, and a third sensor element 2.1.3 having a number ns = 3 of division periods and a division period A3 = 36073. The sensor elements are arranged in different planes and so as to be spaced apart from one another.

[0102] Analogously to the sensor elements 2.1.1, 2.1.2 and 2.1.3, the scale standard has three measuring tracks comprising a first measuring track 1.1 having the division period Ai = 360732, a second measuring track 1.2 having the division period A2 = 36078, and a third measuring track 1.3 having the division period A3 = 36073. Thus, the measuring tracks and the corresponding sensor elements have the same number of division periods. The measuring tracks are arranged in different planes and so as to be spaced apart from one another.

[0103] In the example of Fig. 17, the first measuring channel (m = 32) determines the resolution of the system. The second and the third channel are used for determining the absolute position, wherein the condition GCD (n2, ns) = GCD (8, 3) = 1 is fulfilled.

[0104] In the case of an overlap of the measuring channels, care must be taken that cross-talk of the individual measuring channels with respect to one another is reduced or eliminated. According to one embodiment, the distances between the sensor elements and the associated measuring tracks are selected depending on the number of division periods. In particular, the distances between a measuring track and the respective sensor element can be selected such that the distance dn between the sensor element 2.1.1 having the most division periods, i.e. having the smallest division length, and the associated measuring track 1.1 on the scale standard 1 is the smallest, and the distance d33 between the sensor element 2.1.3 having the fewest division periods, i.e. having the largest division length, and the associated track 1.3 on the scale standard 1 is the largest. The larger the number of division periods of a measuring channel, the smaller the distance between the measuring track and the sensor element of this measuring channel. This situation is shown byway of example in Fig. 17. In particular

[0105] As a result, the conflict with respect to the different operating points of the individual measuring channels, as already set out above with respect to Fig. 10, can be resolved, and furthermore can advantageously be made use of in order to bring signal amplitudes of the individual measuring channels to a similar level. Thus, in particular the sensor electronics can be simplified, for example in that instead of separate evaluation channels for each sensor signal just one physical channel is required, which switches between the individual sensor elements by means of a multiplexer.

[0106] In a further embodiment, the number of division periods of a measuring track having a larger number of division periods is at least a factor of 1.5 larger than the number of division periods of a further measuring track having a smaller number of division periods. For the assembly of Fig. 17, this means the following: A2 1.5 ■ Ai and A3 >1.5 A2. Thus, for the number of division periods the following conditions result: m >1.5 n2 and n? 1.5n2. As set out above, these conditions are fulfilled in the example of Fig. 17, since the following applies: m = 32 >1.5n2(=1.5-8 = 12) and n2 = 8 >1.5 n3(= 1.5-3 = 4.5). Since, in Fig. 17, the number of division periods of the measuring tracks along the z-direction is higher, the number of division periods of a given measuring track is 1.5 times higher than the number of division periods of the measuring track lying directly therebelow.

[0107] According to one example, the number mi of division periods of the sensor elements is equal to the number mi of division periods of the associated scale standard, wherein i is the index of the measuring channel. Thus, for an assembly having three measuring channels the following applies: Ai m = Armi = 1 and A2-n2 = A2 m2 = 1 and As m = As ms = 1, wherein 1 represents the overall length of the scale standard 1. The example of Fig. 17 also fulfils these conditions, because the following applies: Arm = Arrm = 11.25°-32 = 360° and A2-n2 = A2 rri2 = 45°8 = 360° and As m = As-m3 = 120° 3 = 360°. This is advantageous in particular in the case of complete geometric overlapping of the sensor elements of the sensor.

[0108] According to a further example, the distances bi2, b23 between the individual sensor elements and the distances ai2, 823 between the measuring tracks of the scale standard are selected such that in the case of a given distance between the sensor and scale standard (nominal distance) on the one hand the mutual influence of the measuring channels (cross-talk) is minimized, and on the other hand the amplitudes of the signals of the measuring channels are substantially the same. In particular, the amplitudes of the signals of the measuring channels can be within a specified tolerance range. The distances between sensor elements and between measuring tracks are furthermore dependent on the number of division periods for each measuring track and the differences in the numbers of division periods. In any case, the distances by between two sensor elements i and j are in the range of 0.01 to 1.00 mm, and the distances ay between two measuring tracks i and j are in the range of 0.01 mm to 1.00 mm.

[0109] Fig. 18 is a graph showing the signal amplitude of three measuring channels having measuring tracks which have 32, 8 and 3 division periods, respectively, depending on the air gap (operating region). The signal amplitude corresponds to the amplitude of the signal induced in the receiver coil by the emitter signal of the emitter coil. The signal amplitude was calibrated to the interval [0; 1], In order to ensure a constant signal amplitude, for example the distance parameters ai2, a23, bi2 and b23 of the assembly of Fig. 17 can be dimensioned such that, in the case of a given distance between the sensor and scale standard (nominal distance), the air gaps of the measuring channels du = 0.50 mm and d22 = 1.00 mm and d33 = 2.00 mm are the same. This is reproduced by a solid line in Fig. 18, which represents an ideal operating point AP = 0.55.

[0110] Owing to manufacturing tolerances and technical restrictions in production, the permissible operating region of the measuring channels can be defined such that the fluctuation ±A of the signal amplitudes (tolerance range) around the ideal operating point is permitted. In the example of Fig. 18, a fluctuation △ = 0.1 about the operating point AP = 0.55 is selected, which is shown by two dashed lines. Thus, the operating point for the three measuring tracks is between 0.45 and 0.65. It is in particular clear from Fig. 18 that the requirements for the airgap of the measuring channel having the largest number of division periods are higher than the requirements for the air gap of the measuring channel having the smallest number of division periods.

[0111] In one example, the lower limit of the tolerance range is at least 70%, preferably at least 80%, and more preferably at least 90%, of the operating point. In a further example, the upper limit of the tolerance range is no more than 130%, preferably no more than 120%, and more preferably no more than 110%, of the operating point.

[0112] An assembly having partially or completely overlapping measuring tracks or sensor elements has the advantage that the distances between the measuring tracks and the sensor elements can be selected in a flexible manner, such that a similar signal amplitude can be achieved for all the measuring channels. Furthermore, the selection of the operating region is particularly flexible. As can be seen from Fig. 10, this is not the case for conventional assemblies in which the measuring tracks are arranged in the same plane.

[0113] The appropriate selection of the distances between the measuring tracks and the sensor elements makes it possible to substantially reduce cross-talk and mutual impairment of the measuring channels relative to one another.

[0114] According to a further example, the measuring channels are based on different measuring principles and the corresponding sensor elements measure different variables. Thus, the mutual interference of the different measurements can be reduced. For example, a first sensor element can measure a change in the conductivity of the corresponding measuring track, and a second sensor element can measure a change in the permeability / reluctance of the corresponding measuring track. For this purpose, the sensor circuit can be configured to generate a first signal for the first measuring track having a first emitter signal frequency fi, and to feed this into the emitter coil of the first sensor element, and to generate a second signal having a second emitter signal frequency f2 and to feed this into the emitter coil of the second sensor element, wherein the first emitter signal frequency and the second emitter signal frequency differ. In one example, the first emitter signal frequency is at least twice the second emitter signal frequency. Thus, the following applies: fi >2 f2. For example, the sensor element, the emitter coil of which is excited with the smaller emitter signal frequency, measures a permeability or reluctance, while the sensor element, the emitter coil of which is excited with the larger emitter signal frequency, measures a conductivity.

[0115] Fig. 19a is a view from above of a scale standard for an angle-measuring system comprising a magnetic track. Fig. 19b is a view from above of a further scale standard for an angle-measuring system. The width of the annular scale standard in the radial direction changes depending on the angle, such that the scale standard comprises three identical portions, radially, which each have a wider and a narrower region. These portions thus form a periodic measuring track having three periods, which can be referred to as a geometric track. The change in the width of the scale standard can be brought about by a mechanical method, for example by milling, etching, cutting and / or turning. Fig. 19c is a view from above of a further scale standard for an angle-measuring system, which is formed by superposition of the effects from Fig. 19a and 19b. The scale standard thus comprises both the magnetic track of Fig. 19a and the geometric track of Fig. 19b. The two tracks overlap and are arranged in the same axial plane (plane x-y). Since the magnetic field generated by the magnetic track is influenced by the geometry of the scale standard, and thus by the geometric track, a change in the geometry and thus the geometric track can be detected by a corresponding sensor. Thus, the additional geometric measuring track plays the same role as the additional magnetic track of the above examples. The first magnetic measuring track and the second geometric measuring track can thus be formed from a single measuring track-formed part, wherein the geometric measuring track is formed by deformation of the formed part. In the example shown, the greatest common divisor of the two tracks is equal to one, such that the two tracks form a Vernier coding, which can be used for absolute position measurement. The example of Fig. 19c can be used for any number of periods of the magnetic and the geometric track. It can also be implemented in an scale standard of a length measuring system.

[0116] A particularly compact structure can be achieved using a position measuring system in which the different measuring tracks or the sensor elements are arranged so as to be overlapped at least in part. Furthermore, the influence of construction errors on the assembly can be reduced. Since the measuring channels have different distances between the measuring track and sensor element, the operating region can be selected in a particularly flexible manner and thus optimized in a simple manner.

Claims

1. Device (1) for a linear or angle-measuring system, comprising the following: a first measuring track (1.1) having a periodic coding which comprises a first number of division periods, wherein the first measuring track is arranged in a first plane, andat least one second measuring track (1.2) having a periodic coding which comprises a second number of division periods, wherein the second measuring track is arranged in a second plane,wherein the first number of division periods and the second number of division periods differ, andwherein the first plane and the second plane are in parallel with one another, and the first measuring track (1.1) and the second measuring track (1.2) overlap at least in part.

2. Device according to claim 1, wherein the first plane and the second plane are spaced apart from one another.

3. Device according to claim 1, wherein the first and the second measuring track are formed from a single measuring track-formed part.

4. Device according to claim 3, wherein the second measuring track is formed by deforming the measuring track-formed part.

5. Device according to any one of claims 1 to 4, wherein the first measuring track (1.1) and the second measuring track (1.2) overlap completely.

6. Device according to any one of claims 1 to 5, wherein the greatest common divisor of the first number of division periods and the second number of division periods is equal to 1.

7. System, comprising:a device according to any one of claims 1-6, anda sensor head (2) havinga first sensor element (2.1.1) which, together with the first measuring track (1.1), forms a first measuring channel, andat least one second sensor element (2.1.2) which, together with the second measuring track (1.2), forms a second measuring channel,wherein the first and second sensor element cover at least one division period of the first and second measuring track, respectively.

8. System according to claim 7, wherein the first and the second sensor element are arranged in a third and fourth plane, respectively, wherein the third plane and the fourth plane are in parallel with one another and spaced apart from one another.

9. System according to claim 8, wherein the first sensor element (2.1.1) and the second sensor element (2.1.2) overlap at least in part.

10. System according to any one of claims 7 to 9, wherein the first number of division periods of the first measuring track (1.1) is greater than the second number of division periods of the second measuring track (1.2), wherein a first distance between the first measuring track (1.1) and the first sensor element (2.1.1) is configured to be smaller than a second distance between the second measuring track (1.2) and the second sensor element (2.1.2).

11. System according to any one of claims 7 to 10, wherein the first number of division periods of the first measuring track is greater than the second number of division periods of the second measuring track (1.2) by at least a factor of 1.5.

12. System according to any one of claims 7 to 11, wherein distances between the measuring tracks and the corresponding sensor elements are selected such that signal amplitudes of the sensor elements within a given tolerance range are the same.

13. System according to any one of claims 7 to 12, wherein a distance between two measuring tracks arranged directly adjacently is in the range of 0.01 mm to 1.00 mm, and / orwherein a distance between two sensor elements arranged directly adjacently is in the range of 0.01 mm to 1.00 mm.

14. System according to any one of claims 7 to 13, wherein the first and the second sensor element comprise a receiver coil which is configured as a periodic conductor track and comprises a first or second number of division periods, and wherein the number of division periods of the first or of the second sensor element is equal to the number of division periods of the first or of the second measuring track, respectively.

15. System according to any one of claims 7 to 14, wherein the first and the second sensor element each comprise an emitter coil,wherein the sensor head comprises a sensor circuit (2.2) which is configured to generate a first signal having a first emitter signal frequency and to feed it into the emitter coil of the first sensor element, andwherein the sensor circuit (2.2) is further configured to generate a second signal having a second emitter signal frequency and to feed it into the emitter coil of the second sensor element, andwherein the first emitter signal frequency and the second emitter signal frequency differ.

16. System according to claim 15, wherein the first emitter signal frequency is at least twice the second emitter signal frequency.

17. System according to any one of claims 7 to 16,wherein the sensor circuit (2.2) comprises an evaluation circuit having a multiplexer, wherein the multiplexer is connected to the sensor elements and is configured to provide measuring signals via a single physical evaluation channel.

18. Sensor head (2) for a device according to any one of claims 1-6, comprising the following:a first sensor element which is arranged in a third plane and is configured for forming a first measuring channel, together with the first measuring track (1.1),at least one second sensor element which is arranged in a fourth plane and is configured for forming a second measuring channel, together with the second measuring track (1.2),wherein the third plane and the fourth plane are in parallel with one another and spaced apart from one another, wherein the first sensor element (2.1.1) and the second sensor element (2.1.2) overlap at least in part.INTERNATIONAL SEARCH REPORT International application No. PCT / EP2023 / 063489 A. CLASSIFICATION OF SUBJECT MATTER GOW5 / 20(2006M)i; GOW 5 / 245(2006.01)1 According to International Patent Classification (IPC) or to both national classification ar id IPC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) G01D Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched Electronic data base consulted during the international search (name of data base and, where practicable, search terms used) EPO-Intemal, WPI Data C. DOCUMENTS CONSIDERED TO BE RELEVANT Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. X US 2022057281 Al (AUSSERLECHNER UDO [AT]) 24 February 2022 (2022-02-24) abstract; description, paragraphs [0001], [0040]-[0043]; figure 8 1,2, 5-18 X EP 3179214 Al (HEIDENHAIN GMBH DR JOHANNES [DE]) 14 June 2017 (2017-06-14) abstract; description, paragraphs [0015]-[0045]; figures 1-6 1, 3-5, 7, 12, 18 X EP 2924396 Al (HEIDENHAIN GMBH DR JOHANNES [DE]) 30 September 2015 (2015-09-30) abstract: description, paragraphs [0030]-[0047]; figures 1-5 1, 18 X DE 19818799 Al (DAIMLER CHRYSLER AG [DE]) 24 June 1999 (1999-06-24) abstract; description, page 2, line 54 - page 3, line 54; figures 1, 4 1, 18 | | Further documents are listed in the continuation of Box C. | Z | See patent family annex. * Special categories of cited documents: “A” document defining the general state of the art which is not considered to be of particular relevance “E” earlier application or patent but published on or after the international filing date “L” document which may throw doubts on priority claim(s) or which is cited to establish the publication date of another citation or other special reason (as specified) “O” document referring to an oral disclosure, use, exhibition or other means “P” document published prior to the international filing date but later than the priority date claimed “T” later document published after the international filing date or priority date and not in conflict with the application but cited to understand the principle or theory underlying the invention “X” document of particular relevance; the claimed invention cannot be considered novel or cannot be considered to involve an inventive step when the document is taken alone “Y” document of particular relevance; the claimed invention cannot be considered to involve an inventive step when the document is combined with one or more other such documents, such combination being obvious to a person skilled in the ait document member of the same patent family Date of the actual completion of the international search 03 August 2023 Date of mailing of the international search report 14 August 2023 Name and mailing address of the ISA / EP European Patent Office p.b. 5818, Patentlaan 2,2280 HV Rijswijk Netherlands Telephone No. (+31-70)340-2040 Facsimile No. (+31-70)340-3016 Authorized officer Telephone No. Reim, KlausINTERNATIONAL SEARCH REPORT Information on patent family membersInternational application No.PCT / EP2023 / 063489Patent document cited in search report Publication date (day / month / year) Patent family member)s) Publication date (day / month / year) US 2022057281 Al 24 February 2022 CN 114076650 A 22 February 2022 DE 102021209023 Al 24 February 2022 KR 20220022457 A 25 February 2022 US 2022057281 Al 24 February 2022 EP 3179214 Al 14 June 2017 CN 106969695 A 21 July 2017 DE 102015224589 Al 08 June 2017 EP 3179214 Al 14 June 2017 ES 2683650 T3 27 September 2018 JP 6333345 B2 30 May 2018 JP 2017106920 A 15 June 2017 US 2017160102 Al 08 June 2017 EP 2924396 Al 30 September 2015 CN 104949613 A 30 September 2015 DE 102014205397 Al 24 September 2015 EP 2924396 Al 30 September 2015 JP 6558923 B2 14 August 2019 JP 2015184282 A 22 October 2015 US 2015268066 Al 24 September 2015 DE 19818799 Al 24 June 1999 NONE

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