ROTATION ANGLE SENSOR SYSTEM, LIDAR SYSTEM, WORK DEVICE AND OPERATING METHOD FOR A LIDAR SYSTEM

Abstract

A rotation angle sensor system for an optical system including a rotor and a stator, for determining a rotation angle and/or an orientation between the rotor and the stator. The system includes a coil system that is stator-based and attached in a rotatably fixed manner to the stator as a sensor element for receiving a magnetic alternating field, and has a target that is rotor-based and attached in a rotatably fixed manner to the rotor for generating a magnetic alternating field, and in which the coil system and the target are attached to the stator and to the rotor in such a way that different overlaps and/or spatial proximities occur between the coil system and the target as a function of the rotation angle and/or of the orientation between stator and rotor with a correspondingly different effect on the magnetic alternating field of the target on the coil system.

Claims

1. A rotation angle sensor system for an optical system that includes a rotor and a stator, for determining a rotation angle and/or an orientation between the rotor and the stator, the rotation angle sensor system comprising: a coil system as a sensor element for receiving a magnetic alternating field, which is stator-based and attached in a rotatably fixed manner to the stator; and a target for actively generating a magnetic alternating field, which is rotor-based and attached in a rotatably fixed manner to the rotor; wherein the coil system and the target are attached to the stator and to the rotor in such a way that at least one of (i) different overlaps occur, and (ii) different spatial proximities occur, between the coil system and the target as a function of at least one of: (i) a rotation angle between the stator and the rotor, and (ii) an orientation between the stator and the rotor, with a correspondingly different effect on the magnetic alternating field of the target on the coil system.

2. The rotation angle sensor system as recited in claim 1, wherein the optical system is a LIDAR system.

3. The rotation angle sensor system as recited in claim 1, wherein at least one of: (i) the rotation angle sensor system is configured to actively energize the target for actively generating a magnetic alternating field, (ii) the rotation angle sensor includes a first voltage source which is designed at least one of: for supplying power to the target in the manner of a converter, adapting frequency of an input signal, adapting an amplitude of an input signal, and adapting a phase of an input signal, and (iii) the target is connected to the first voltage source via a connecting device.

4. The rotation angle sensor system as recited in claim 1, wherein the coil system includes at least one coil element as a receiving coil, wherein at least one of: (i) a respective coil element is designed as a planar coil, (ii) a respective coil element has a shape in cross section or in a plane of a coil winding, that includes an even number of identical partial windings or partial turns adjacent to one another, with directly adjacent partial windings or partial turns rotating in the opposite direction, (iii) a respective coil element includes first and second terminals, (iv) the coil system includes a plurality of identically designed coil elements that are connected in series, rotated toward one another and/or uniformly cover a full angle, and (v) the coil system is designed mirror-symmetrically with respect to a rotational axis between stator and rotor, (vi) the coil system is designed rotationally-symmetrically with respect to a rotational axis between stator and rotor.

5. The rotation angle sensor system as recited in claim 1, wherein the target at least one of: (i) is designed in the manner of a planar transmitter coil that includes terminals and at least one of: (a) at least one winding, and (ii) multiple turns, in a plane in parallel to a plane defined by the coil element of the coil system of the receiving coil, and (ii) is designed in the manner of a short circuit ring.

6. The rotation angle sensor system as recited in claim 5, wherein at least one of (i) the target includes an equal number of first sections and second sections, each of which are designed to be identical to each other, overall identical, in an alternating sequence and/or uniformly covering a full angle with respect to an underlying rotational axis, (ii) a respective first section of the target is configured for a current flow at at least one of a greater distance, and along a greater radius, with respect to a rotational axis between the stator and the rotor, and a respective second section of the target is configured for a current flow at at least one of a smaller distance, and along a smaller radius, with respect to the rotational axis, (iii) a respective first section of the target and a respective second section of the target are electrically connected on the input side and output side, in each case to second sections, and first sections preceding and following in the circumferential direction, relative to a rotational axis between the stator and the rotor, with the aid of connecting sections, which connect successive, radially extending first sections and second sections for a radial current flow in a circumferential direction, (iv) the target is mirror-symmetrically designed with respect to a rotational axis between the stator and the rotor, and (v) the target is rotationally-symmetrically designed with respect to a rotational axis between the stator and the rotor.

7. The rotation angle sensor system as recited in claim 1, wherein the coil system of the sensor element and the target are attached to the stator and to the rotor in such a way that the coil system and the target are at least one of: (i) situated in planes in parallel with one another, and (ii) situated a minimal distance apart from one another.

8. The rotation angle sensor system as recited in claim 7, wherein the minimal distance is less than 5 mm.

9. The rotation angle sensor system as recited in claim 7, wherein the minimal distance is less than 2 mm.

10. The rotation angle sensor system as recited in claim 7, wherein the minimal distance is under 1 mm.

11. The rotation angle sensor system as recited in claim 1, wherein at least one of: (i) the coil system for the sensor element is designed as at least part of a circuit board structure on the stator side, and (ii) the target is designed as at least part of a circuit board structure on the rotor side.

12. A LIDAR system for visually detecting a visual field for a work device and/or for a vehicle, the LIDAR system comprising: a rotor; a stator; a drive for rotor relative to the stator about a rotational axis; and a rotation angle sensor system for determining a rotation angle and/or an orientation between the rotor and the stator, the rotation angle sensor system including a coil system as a sensor element for receiving a magnetic alternating field, which is stator-based and attached in a rotatably fixed manner to the stator, and a target for actively generating a magnetic alternating field, which is rotor-based and attached in a rotatably fixed manner to the rotor, wherein the coil system and the target are attached to the stator and to the rotor in such a way that at least one of (i) different overlaps occur, and (ii) different spatial proximities occur, between the coil system and the target as a function of at least one of: (i) a rotation angle between the stator and the rotor, and (ii) an orientation between the stator and the rotor, with a correspondingly different effect on the magnetic alternating field of the target on the coil system.

13. The LIDAR system as recited in claim 12, wherein: at least one of the rotor and a transmitter optical system that includes a light source unit encompassed by the rotor, and a receiver optical system that includes a detector system, are configured for wirelessly supplying power with the aid of induction; and the stator includes a primary coil designed for generating and emitting a magnetic alternating field and the rotor includes a secondary coil for receiving the magnetic alternating field of the primary coil and for generating an induction voltage as an operating voltage, magnetically coupled to one another, each magnetically coupled to a ferrite element.

14. The LIDAR system as recited in claim 13, wherein at least one of: a ferrite element of the primary coil on the stator side is formed below the coil system for the sensor element; the primary coil on the stator side is designed to at least one of be partially perforated, and at least partially enclose a ferrite element of the primary coil on the stator side; a carrier of the primary coil is designed to at least one of be partially perforated, and at least partially enclose a ferrite element of the primary coil on the stator side; and a ferrite element of the secondary coil on the rotor side at least one of is structured to accommodate the target in a recess, and includes a materially modified area as target in the form of at least one of an implantation and a coating.

15. The LIDAR system as recited in claim 12, wherein the rotor includes at least one of: a first voltage source for supplying power to the target, the first voltage source at least one of: (i) includes a converter for adapting at least one of a frequency of an input signal, an amplitude of an input signal, and a phase of an input signal, and (ii) is electromagnetically coupled to the secondary coil on the rotor side for supplying power; and a second voltage source for supplying power to the rotor and at least one of: (i) to a drive of the rotor, (ii) to a transmitter optical system including a light source unit encompassed by the rotor, and (iii) to a receiver optical system including a detector system, the second voltage source at least one of: (i) including a rectifier, and (ii) is electromagnetically coupled to the secondary coil on the rotor side for supplying power.

16. A vehicle that includes a LIDAR system for visually detecting a visual field, the LIDAR system comprising: a rotor; a stator; a drive for rotor relative to the stator about a rotational axis; and a rotation angle sensor system for determining a rotation angle and/or an orientation between the rotor and the stator, the rotation angle sensor system including a coil system as a sensor element for receiving a magnetic alternating field, which is stator-based and attached in a rotatably fixed manner to the stator; and a target for actively generating a magnetic alternating field, which is rotor-based and attached in a rotatably fixed manner to the rotor, wherein the coil system and the target are attached to the stator and to the rotor in such a way that at least one of (i) different overlaps occur, and (ii) different spatial proximities occur, between the coil system and the target as a function of at least one of: (i) a rotation angle between the stator and the rotor, and (ii) an orientation between the stator and the rotor, with a correspondingly different effect on the magnetic alternating field of the target on the coil system.

17. An operating method for a LIDAR system, the LIDAR system including a rotor, a stator, a drive for rotor relative to the stator about a rotational axis, and a rotation angle sensor system for determining a rotation angle and/or an orientation between the rotor and the stator, the rotation angle sensor system including a coil system as a sensor element for receiving a magnetic alternating field, which is stator-based and attached in a rotatably fixed manner to the stator, and a target for actively generating a magnetic alternating field, which is rotor-based and attached in a rotatably fixed manner to the rotor, wherein the coil system and the target are attached to the stator and to the rotor in such a way that at least one of (i) different overlaps occur, and (ii) different spatial proximities occur, between the coil system and the target as a function of at least one of: (i) a rotation angle between the stator and the rotor, and (ii) an orientation between the stator and the rotor, with a correspondingly different effect on the magnetic alternating field of the target on the coil system, the method comprising: wirelessly receiving in a rotor a supply signal; and at least one of: converting the supply signal in at least one of amplitude, frequency and phase, using a converter, to operate the target of the rotation angle sensor and to excite transmitter coils of the target, and or converting the supply signal using a rectifier to operate additional components of the LIDAR system in the rotor, the additional components including at least one of: (i) a drive of the rotor, (ii) a transmitter optical system encompassed by the rotor that includes a light source unit, and (iii) a receiver optical system that includes a detector system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Specific example embodiments of the present invention are described in detail with reference to the figures.

[0040] FIG. 1 shows in the manner of a schematic block diagram the structure of a specific embodiment of the LIDAR system according to the present invention.

[0041] FIG. 2 shows in a schematic and partially sectioned side view details of a specific embodiment of the LIDAR system according to the present invention using a specific embodiment of the rotation angle sensor system according to the present invention.

[0042] FIGS. 3 and 4 schematically show a top view of specific embodiments of the coil system for a sensor element usable according to the present invention.

[0043] FIG. 5 shows in the form of a graph signals detectable with one specific embodiment of the coil system according to the present invention as a sensor element.

[0044] FIGS. 6 and 7 schematically show a top view of specific embodiments of the target usable according to the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0045] Exemplary embodiments of the present invention and the technical background are described in detail below with reference to FIGS. 1 through 7. Identical and equivalent elements as well as identically or equivalently functioning elements and components are identified with the same reference numerals.

[0046] The features and additional properties depicted may be isolated in arbitrary form from one another and may be arbitrarily combined with one another without departing from the present invention.

[0047] FIG. 1 shows in the form of a schematic block diagram one specific embodiment of the LIDAR system 1 according to the present invention that includes an optical system 10.

[0048] LIDAR system 1 according to FIG. 1 includes a transmitter optical system 60 in its optical system 10 with an optical path 61, which is fed by a light source unit 65 that includes light sources 65-1, for example, here in the form of lasers, and which emits primary light 57if necessary after passing through beam shaping optical system 66 and via deflection optical system 62into a visual field 50 for detecting an object 52 of a scene 53 located in the visual field.

[0049] In addition, LIDAR system 1 according to FIG. 1 includes a receiver optical system 30 with optical path 31, which receives secondary light 58 reflected by object 52 in visual field 50 via a lens 34 as primary optical system and which transmits it via secondary optical system 35 to a detector system 20 for detection that includes sensor elements or detector elements 22. Secondary optical system 35 may include a bandpass filter in order to reduce the influence of scattered light.

[0050] Light source unit 65 including light sources 65-1 and detector system 20 are controlled via control channels 42 and 41 with the aid of a control and evaluation unit 40. Control and evaluation unit 40 may also assume the power transmission and/or data transmission between rotor 200 and stator 100 and, in particular, the control of a rotary drive. However, it is configured, in particular, to carry out the assessment of visual field 50 via control system 45 with connection via bus 46 to transmitting unit 47, receiving unit 49 and correlation unit 48.

[0051] It is also apparent from FIG. 1 that control and evaluation unit 40 is designed in conjunction with stator 100, whereas optical system 10 of LIDAR system 1 is accommodated essentially in rotor 200.

[0052] The control of the operation of LIDAR system 1 according to the present invention according to FIG. 1 and the implementation of a corresponding operating method take place using control system 45 depicted in FIG. 1, in which transmitting unit 47, receiving unit 49 and correlation unit 48 are linked to one another via a bus 46 and are operatively connected via control lines 41 and 42 to optical system 10 of LIDAR system 1 in rotor 100 and, in particular, to light source unit 65 and detector system 20 of transmitter optical system 60, or receiver optical system 30.

[0053] FIG. 2 shows in a schematic and partially sectioned side view details of a specific embodiment of LIDAR system 1 according to the present invention using a specific embodiment of rotation angle sensor system 5 according to the present invention.

[0054] In the specific embodiment according to FIG. 2, stator 100 includes, in addition to primary coil 102 on the stator side and ferrite element or ferrite core 301, a circuit board structure 103 on the stator side, which includes a coil system 105 as a sensor element or for a sensor element in conjunction with the determination of the orientation of the rotation angle of rotor 200 relative to stator 100.

[0055] In addition to optical system 10, which includes transmitter optical system 60 and receiver optical system 30 and additional elements 304 of LIDAR system 1, rotor 200 includes a secondary coil 201 having a ferrite element or ferrite core 302, the induced voltage (i) in secondary coil 201 magnetically coupled to primary coil 102 and to ferrite elements 301, 302 being fed on the one hand to a voltage converter 303 and, in particular, to a rectifier, in order to generate an operating voltage for LIDAR components 304 and, on the other hand, being fed to a converter 202 in order to provide target 203 including corresponding field coils, with an operating voltage for operating the field coils and thereby effectuating an excitation of target 203.

[0056] In the specific embodiment according to FIG. 2, circuit board structure 103 including coil system 105 of the sensor element or for the sensor element is formed directly above ferrite element 301 of primary coil 102, target 203 being functionally provided and situated as a controllably operable exciter in close or direct proximity thereto.

[0057] Rotor 200 is rotatable relative to stator 100 about a rotational axis 500, a corresponding rotary drive being used, which is not depicted herein.

[0058] A generator 101, which applies an AC voltage to primary coil 102 on the stator side, is designed to transmit power from stator 100 to rotor 200 using the arrangement made up of primary coil 102 and secondary coil 201 coupled via ferrite cores 301 and 302. The electromagnetic coupling to rotor 200 then results in a voltage induced in secondary coil 201, which is fed via rectifier 303 to additional components 304 of LIDAR system 1 for the operation thereof and, on the other hand, mediated by converter 202, results in the excitation of target 203.

[0059] FIGS. 3 and 4 schematically show a top view of specific embodiments of coil system 105 usable according to the present invention as a sensor element or for a sensor element in the area of stator 100.

[0060] FIG. 3 shows an example of a specific embodiment of a receiving coil 103.1 usable on the stator side, as it may be designed according to the present invention, for example, as an element of circuit board structure 103 for a coil system 105 as a sensor element.

[0061] Receiving coil 103.1 or receiver coil according to FIG. 3 is formed from a winding 103.3 having one or multiple turns. In the specific embodiment depicted in FIG. 3, winding 103.3 of receiver coil 103.1 is formed on the stator side

(a) by a first section or a first partial winding 103.4 having a first circumferential direction for the electrical current based on the orientation of first partial winding 103.4 or of the turns thereof, depicted by a first arrow 103.6, and
(b) by a second section or by a second partial winding 103.5 having a second circumferential direction for the electric current based on the orientation of second partial windings 103.5 or of the turns thereof, depicted by a second arrow 103.7.

[0062] A contacting of receiving coil or receiver coil 103.1 may take place via first terminals 104.1 and 104.2 for contacting winding 103.3.

[0063] FIG. 4 shows the structure of a coil system 105 for a sensor element in stator 100, preferably constructed in conjunction with a circuit board structure, having a first receiving coil or receiver coil 103.1 and a second receiving coil or receiver coil 103.2 constructed identically thereto, but which is rotated 90 clockwise relative to first receiver coil 103.1. First and second receiver coils 103.1 and 103.2 of coil system 105 as a sensor element each include a winding 103.1 having a first partial winding 103.4 and a second partial winding 103.5 and first and second terminals 104.1 and 104.2. The properties for each of first and second receiving coils 103.1, 103.2 specified in conjunction with FIG. 3 otherwise apply.

[0064] FIG. 5 shows in the form of a graph 70 signals or partial signals detectable with a specific embodiment of coil system 105 according to the present invention as a sensor element, mediated by corresponding sections or partial windings 103.4 and 103.5 of a receiving coil 103.1. According to one preferred embodiment of the present invention, target 203 is constructively and, in particular, geometrically designed in such a way that the signals, induced by induction and received in receiving coils 103.1 and 103.2, and which are plotted in graph 70, in which the time is plotted on the x-axis 71 and the signal strength is plotted on the y-axis 72, as they are depicted in tracks 73 and 74, exhibit a corresponding sinusoidal curve, where applicable, with a corresponding phase shift. The orientation and/or the rotation angle of rotor 200 relative to stator 100 as well as changes thereto may then be inferred by calculation methods carried out accordingly.

[0065] FIGS. 6 and 7 schematically show a top view of specific embodiments of target 203 usable according to the present invention.

[0066] Target 203 is depicted in FIG. 6 as a transmitter coil 204, specifically, essentially in the manner of a short circuit ring that includes a turn, at the only break of which a first terminal 104.1 and a second terminal 104.2 are formed with a connection to a converter 202, converter 202 being fed via the secondary coil 201 on rotor 200 inductively coupled to a primary coil 102 on the stator side.

[0067] Target 203 according to FIG. 6 has a three-fold rotational symmetry or rotational symmetry around rotational axis 500 between stator 100 and rotor 200 perpendicular to the drawing plane. Target 203 is formed by a sequence of alternatingly situated first and second sections 204.4 and 204.6 of winding 204.3 or turn of target 203. First and second sections 204.4 and 204.6 each extend essentially in the circumferential direction of the rotation symmetry at a fixed distance or radius from rotational axis 500, namely once at a greater distance for first sections 204.4 and once at a distance or radius located closer to axis 500 for second sections 204.6. Each first section 204.4 of winding or turn 204.3 of target 203 is electrically conductively connected on the input side and the output side, respectively, with a second section 204.6 of winding or turn 204.3 of target 203, in each case with the aid of radial section 204.5. Accordingly, each second section 204.6 of winding or turn 204.3 of target 203 is electrically conductively connected on the input side and the output side, respectively, with a first section 204.4 of winding or turn 204.3 of target 203, in each case with the aid of a radial section 204.5.

[0068] First and second sections 204.4 and 204.6 span the full angle of 360, specifically, preferably at identical angles , , as is depicted in conjunction with FIG. 7.

[0069] These features and additional features and properties of the present invention are explained further based on the following elucidations.

[0070] The present invention relates, in particular, to LIDAR systems 1 in the form of so-called LIDAR macroscanners, in which all required optical elements 304 and, in particular, a laser as light source 65-1 and a detector system 20 that includes a detector element 22 are seated on a rotor 200, but also LIDAR systems 1 in the manner of scanners, in which a mirror for beam deflection rotates and thus a visual field 50 and scene 53 with object 52 included therein are scanned.

[0071] In both cases, a beam of primary light 57 is emitted with a pulsed light source 65-1for example, a laserand the reflection thereof is detected as secondary light 58, in order to implement a distance measurement and to record an image of scene 53. The power supply of rotating systems 1 may be implemented wirelesslyfor example, via a combination of primary coil 102 on the stator side and secondary coil 201 on the rotor side, whereas many conventional LIDAR systems operate with slip rings.

[0072] The rotor position must be known in order to commutate the motor and to calculate the scene image. A rotation angle sensor 5 is used for this purpose.

[0073] In this case, coupled coils are conventionally used for such a rotation angle sensor. An electromagnetic alternating field, which couples into multiple receiving coils of the conventional rotation angle sensor where in each case it induces a voltage, is formed in a field coil. The measurement of the rotation angle requires a rotatably mounted, conductive target, which influences the inductive coupling between the field coil and the receiving coils as a function of its angular position and relative to the receiving coils.

[0074] The exciter field specifically provides an induced voltage in the target structure resulting in a current flow, which in turn a magnetic field, which then induces voltages in the field coils. For reasons of electromagnetic capability, the field emission of the field coil is limited, which also results in a limited maximum distance between the sensor board that has the coil structures and the target. The minimal distance may result in the exclusion of the concept in some implementations of the macroscanner.

[0075] An object of the present invention is to provide the integration of an inductive rotation angle sensor 5 into a wirelessly powered scanning optical system and, in particular, into a corresponding LIDAR system 1.

[0076] According to the present invention, target 203 of sensor 5 is directly energized in the process, so that a field coil on sensor circuit board 103 is no longer necessary and greater distances between target 203 and receiving coils 103.1 and 103.2 of coil system 105 on the stator side are possible for the sensor element.

[0077] Thus, in accordance with the present invention, an inductive rotation angle sensor 5 is integrated into a wirelessly powered scanning optical system, in particular, of a LIDAR system 1. The wirelessly powered rotor 200 supplies target 203 of inductive rotation angle sensor 5 directly with power, so that an excitation on the side of stator 100 may be dispensed with, namely where receiving coils 103.1, 103.2 of coil system 105 on the stator side of rotation angle sensor 5 are placed.

[0078] The following advantages, among others, result: [0079] The measuring principle is independent of external magnetic fields which, for example, are generated by the stator coils of the motor (external magnetic field immunity). [0080] An overall simple system 1 is formed. [0081] Comparatively little additional hardware outlay is necessary. [0082] The absolute position in connection with the uniqueness range of the sensor may already be known at the system start. This is important, in particular, for the motor commutation of the BLDC motor, specifically in synchronous machines. [0083] The power transmission and the transmission of the sensor signals do not interfere with one another. [0084] An overall easily implementable redundancy concept results, for example, according to ISO 26262, for rotation angle sensor 5, in particular, with the possibility of integrating additional receiving coils and without additional costs. [0085] The concept according to the present invention is robustly tolerant and temperature-stable, i.e. thermal expansion does not result in measuring errors. [0086] The overall result is a comparatively high measuring sensitivity or sensitivity of rotation angle sensor 5 according to the present invention. [0087] The measuring principle provided according to the present invention is independent of many additional external influences, such as humidity, lubricants, etc.

[0088] A system according to the present invention as LIDAR system 1 including the required components is depicted in FIG. 2.

[0089] A rotor 200 is rotatably mounted about a rotational axis 500. Located opposite the rotor is a stator 100 assumed to be fixed.

[0090] Power is supplied to components 304 of LIDAR system 1 and additional components on rotor 200 via a primary coil 102, to which an AC voltage signal having a frequency range of several tens of kHz to several hundred kHz is applied by a generator 101, and to a secondary coil 201.

[0091] Ferrite cores 301 and 302 may be used in order to ensure an effective power transmission.

[0092] On the secondary side of rotor 200, the AC voltage may, for example, be rectified or further processed in another form using a voltage converter 303, for example, by smoothing or while smoothing, conversion to other frequencies, amplitudes and/or phases, in order to then supply additional components 304 of LIDAR system 1. These components are not further depicted here, but include at least light source 65-1, for example, a laser, and a detector system 20 that includes one or multiple detector elements 22.

[0093] Also not depicted are the required components for wireless data transmission between rotor 200 and stator 100, the motor for rotating rotor 200 as well as the requisite control unit.

[0094] According to the present invention, stator 100 includes, for example, a circuit board structure 103, which carries at least receiving coils 103.1 and 103.2 of coil system 105 of rotation angle sensor 5.

[0095] Ferrite element 301 on the stator side may either be situated below circuit board structure 103 as is depicted or else at least partially enclose this circuit board structure. It is also conceivable that circuit board structure 103 includes openings, via which ferrite element 301 on the stator side jacks at least partially through circuit board structure 103.

[0096] On the rotor side, system 1 according to the present invention includes a target 203 as a controllable exciter. This target 203 is electrically conductively designed in several areas. It may, for example, be a circuit board or else also a milled or punched part made of aluminum. Furthermore, it is also possible to structure ferrite element 302 on the rotor side accordingly and to insert an electrically conductive element or to at least provide ferrite element 302 with an electrically conductive coating.

[0097] Target 203 is actively electrically powered, i.e. is energized. According to the present invention, a voltage source, for example, in the form of a voltage converter 202in particular, in the manner of a converteris integrated for this purpose on the rotor side, which modulates the induced voltage of secondary coil 201 in frequency, optionally in amplitude and/or in phase. While the induced voltage of secondary coil 201 may include frequencies in the range of several 100 kHz, target 203 may be supplied with voltages having frequencies in the range of a few MHzfor example 5 MHz.

[0098] FIG. 3 shows a scheme of a receiving coil 103.1 on circuit board structure 103 having a measuring range of a total of 360.

[0099] Receiving coil 103.1 includes surfaces of identical size and an identical number of partial turns or partial windings 103.4, 103.5 in clockwise and counterclockwise rotation. A measuring range of 360 requires one partial turn each, a measuring range of 180 requires two each and so forth. It should be noted that adjacent partial turns 103.4, 103.5 always rotate in opposite directions.

[0100] At least two receiving coils 103.1 and 103.2 according to FIG. 4 are preferably used to enable a robust back-calculation into the rotation angle. These receiving coils are rotated or are to be rotated by a quarter of the measuring range toward one another. If three receiving coils are used, these receiving coils are rotated by a third of the measuring range.

[0101] FIG. 4 schematically shows the arrangement of two receiving coils 103.1, 103.2 on circuit board structure 103.

[0102] The two receiving coils 103.1, 103.2 depicted have an essentially identical geometry, but are depicted for reasons of clarity with slightly different diameters.

[0103] To demodulate the received signals, the carrier of the excitation signal of the target, namely the output signal of AC/AC converter 202, is reconstructed, for example, with the aid of known techniques of carrier recovery.

[0104] In-phase demodulation of the received signals with the excitation signal of target 203 results, for example, for two receiving coils according to FIG. 4, in signals of receiving coils 103.1 and 103.2, as they are depicted in FIG. 5 in tracks 73 and 74 of graph 70.

[0105] Target 203 is preferably geometrically designed in such a way that the amplitude of the received signals changes in a sinusoidal manner with the rotation angle, as shown in FIG. 5. For two receiving coils 103.1, 103.2, the above described rotation results in a sine/cosine system, which may be carried over into the rotation angle by division and arc tangent calculation.

[0106] Alternatively, other signal shapes having correspondingly different back-calculation algorithms are also possible, for example, having a linear amplitude curve as a function of the rotation angle.

[0107] FIG. 6 is a schematic diagram of a target 203 according to the present invention as a transmitter coil or transmitter coil 204, including the required components for supplying current on rotor 200.

[0108] FIG. 6 shows, in particular, secondary coil 201 on the rotor side, only one turn being depicted for reasons of clarity. The signal received by primary coil 102 via secondary coil 201 is converted via voltage converter 202 into an AC voltage of a different frequency, amplitude and/or phase, and directly supplies a target structure 203, in which a current flow consequently results.

[0109] Target structure 203, as depicted, may essentially be a short circuit ring. However, the target preferably includes three or more turns in order to achieve a sufficiently high inductance. In principle, the adaptation of the impedance of target structure 203 to the impedance of converter 202 should be sought in order to achieve a maximum current flow. This current flow in turn ensures a maximum magnetic field and maximally induced voltages in receiving coils 103.1, 103.2 of stator 100.

[0110] Target 203 is constructed preferably according to FIG. 7 in such a way that in an angle range , the current flow is concentrated on an outer circular arc element 204.4 of winding 204.3 of target 203, which has an outer radius and on a directly adjacent angle range the current flow takes place on an interior circular arc element 204.6. Between these are radially extending, conductive elements or sections 204.5, all of which intersect in their extensions in the point center of symmetry of rotational axis 500 of target structure 203. The sum of the two angle ranges and equals the measuring range. Preferably, = applies.

[0111] Alternatively, target element 203 may also include more complex structures on a circuit board. This may be a single layer, but also a multilayer circuit board.