Absolute rotary encoder for detecting the rotational movement of a shaft

Abstract

The invention relates to an absolute rotary encoder (100) for detecting the rotational movement of a shaft (101), comprising: a revolution counting device (3) for determining a revolution count value (U), comprising a Wiegand sensor (3.1), a magnetic field sensor (3.2), and a permanent-magnetic rotor unit (3.3) which is designed to be mounted so as to rotate with the shaft (101), and which is designed in such a way that, when mounted, the permanent-magnetic rotor unit (3) generates a magnetic field alternating at least four times per rotation at the location of the Wiegand sensor (3.1) during uniform rotation of the shaft (101); an angular position measuring device (4) for measuring the current angular position (W) of the shaft (101); and an evaluation device (5) having a non-volatile data memory (5.1) in which the revolution count value (U) and a revolution sector value (US-g) are stored, wherein the evaluation device (5) is designed, after an interruption of the external power supply: to calculate an initial revolution sector value (US-e) on the basis of the current angular position (W) measured by the angular position measuring device (4); and to increase, decrease, or leave unchanged a determined current absolute position (AP) depending on the calculated initial revolution sector value (US-e) and the stored revolution sector value (US-g).

Description

[0001] DESCRIPTION

[0002] Absolute encoder for detecting the rotary movement of a shaft

[0003] The present invention relates to an absolute rotary encoder for detecting a rotational movement of a shaft, comprising: a revolution counting device for determining a revolution count, with a Wiegand sensor, a magnetic field sensor, and a permanent-magnetic rotor unit, which is designed to be mounted on the shaft and which is configured such that an alternating magnetic field is generated by the permanent-magnetic rotor unit in the mounted state during a uniform rotational movement of the shaft at the location of the Wiegand sensor, an angular position measuring device for determining a current angular position of the shaft, and an evaluation device with a non-volatile data memory in which the revolution count is stored, wherein the evaluation device is designed, based on output signals of the Wiegand sensor and the magnetic field sensor,to determine a current absolute position from the stored revolution count value and the current angular position determined by the angular position measuring device.

[0004] Such an absolute encoder is known from WO 2004 / 046735 A1. In the described absolute encoder, to synchronize the revolution counter and the angular position measuring device, i.e., to determine a correct current absolute position, the magnetization state of the Wiegand wire is detected after an interruption of an external power supply by energizing a coil surrounding a Wiegand wire of the Wiegand sensor. However, this requires relatively complex electronics.

[0005] Against this background, the task arises of realising an absolute rotary encoder of the type mentioned above which operates reliably even after an interruption of an external power supply and which can be manufactured relatively inexpensively.

[0006] This object is achieved according to the invention by an absolute rotary encoder for detecting a rotary movement of a shaft having the features of claim 1.

[0007] The absolute rotary encoder according to the invention for detecting a rotary movement of a shaft comprises a revolution counter for determining a current revolution counter value. Such revolution counter devices are also referred to as multi-turn sensor devices and are generally known from the prior art. The revolution counter value generally indicates the number of complete revolutions completed in a specified positive direction of rotation since initialization. The revolution counter value is typically increased by one each time a zero-angle position is traversed in the positive direction of rotation and decreased by one each time the zero-angle position is traversed in a negative direction of rotation opposite to the positive direction of rotation.In principle, it is also conceivable that the revolution count indicates the number of partial revolutions completed, for example, the number of half revolutions completed, in the positive direction of rotation. In any case, however, the number of complete revolutions completed can be directly and unambiguously derived from the revolution count.The absolute rotary encoder according to the invention for detecting a rotary movement of a shaft specifically comprises a Wiegand sensor-based revolution counter, which is also known in principle from the prior art and which comprises a Wiegand sensor, preferably a single Wiegand sensor, a magnetic field sensor, and a permanent-magnetic rotor unit, wherein the Wiegand sensor and the magnetic field sensor are designed to be arranged stationary relative to the shaft whose rotary movement is to be detected, and the permanent-magnetic rotor unit is designed to be mounted so as to rotate with the shaft whose rotary movement is to be detected, i.e. to be mounted in such a way that a rotary movement of the shaft necessarily results in a rotary movement of the permanent-magnetic rotor unit.

[0008] The Wiegand sensor comprises a Wiegand wire and a sensor coil surrounding the Wiegand wire. Such Wiegand sensors are also referred to as pulse wire sensors and are generally known from the prior art. Wiegand wires generally have a hard magnetic sheath and a soft magnetic core, or vice versa. Under the influence of an external magnetic field, the magnetization direction of the Wiegand wire suddenly inverts, generating a short Wiegand voltage pulse in the sensor coil radially surrounding the Wiegand wire. This pulse can be tapped via the sensor coil ends, i.e., both ends of the sensor coil. This effect is known as the Wiegand effect, or also as the macroscopic or large Barkhausen effect, and is well known.

[0009] The magnetic field sensor can in principle be any magnetic field sensor known from the state of the art, for example a Hall sensor, a field plate, a TMR sensor, an AMR sensor or a GMR sensor.

[0010] The permanent-magnet rotor unit is preferably designed to be attached directly to the shaft, so that the permanent-magnet rotor unit and the shaft always rotate at the same speed. However, it is also conceivable for the permanent-magnet rotor unit to be coupled to the shaft via a gear, so that the permanent-magnet rotor unit and the shaft rotate at different speeds. The permanent-magnet rotor unit is designed in a known manner such that, when mounted, the permanent-magnet rotor unit generates an alternating magnetic field at the location of the Wiegand sensor during a uniform rotation of the shaft.The permanent-magnet rotor unit can, for example, comprise a permanent-magnet ring magnet arranged circumferentially around a rotational axis of the rotor unit, which has a sequence of magnetic north poles and magnetic south poles along its circumference. However, the permanent-magnet rotor unit can also comprise several separate permanent magnets arranged on a circular path circumferentially around the rotational axis of the rotor unit, with adjacent permanent magnets each having opposite polarity. In any case, the permanent-magnet rotor unit comprises at least one permanent magnet.

[0011] According to the invention, the permanent magnetic rotor unit is specifically designed such that the magnetic field generated by the permanent magnetic rotor unit in the mounted state at the location of the Wiegand sensor alternates at least four times per revolution during a uniform rotational movement of the shaft, so that during a uniform rotational movement of the shaft per revolution, a Wiegand voltage pulse is generated in the Wiegand sensor at at least four different angular positions, hereinafter referred to as trigger angular positions.Preferably, the permanent magnetic rotor unit is designed such that the magnetic field generated by the permanent magnetic rotor unit in the mounted state at the location of the Wiegand sensor alternates with a constant frequency during a uniform rotational movement, so that the four trigger angle positions are approximately equidistant, i.e. there is always an approximately equal angular distance between two successive trigger angle positions.

[0012] The absolute rotary encoder according to the invention for detecting a shaft's rotary motion further comprises an angular position measuring device for determining a current angular position of the shaft. Such angular position measuring devices are also referred to as single-turn sensor devices and are generally known from the prior art. The angular position indicates a rotational position of the shaft whose rotary motion is to be detected within one revolution and can therefore be between 0° and 360°. The angular position measuring device comprises a rotor unit, which, analogous to the permanent-magnet rotor unit of the revolution counter device, is designed to be mounted so as to rotate with the shaft whose rotary motion is to be detected, and a stator unit, which is designed to be arranged stationary relative to the shaft whose rotary motion is to be detected.Typically, the stator unit comprises a sensor or detection electronics that interacts with a passive, i.e., non-electrically contacted, coding element arranged on the rotor unit to determine the angular position. The coding element is designed such that a physical property detected by the sensor or the detection electronics changes in a defined manner during a rotational movement of the rotor unit, such that the current angular position can be derived from a current value of the physical property. The angular position measuring device can, for example, be an optical angular position measuring device, in which the coding element comprises a defined sequence of light and dark areas that are scanned with an optical sensor.In principle, however, the angular position measuring device can be any angular position measuring device known from the prior art, such as a magnetic angular position measuring device, a capacitive angular position measuring device or an inductive angular position measuring device.

[0013] The absolute rotary encoder according to the invention for detecting the rotary movement of a shaft further comprises an evaluation device with a non-volatile data memory, preferably a so-called FRAM. In addition to the non-volatile data memory, the evaluation device comprises processing electronics designed to process output signals or output values ​​from the revolution counter and the angular position measuring device. The evaluation device typically comprises a microcontroller, a so-called FPGA, or another type of arithmetic and logic unit.

[0014] According to the invention, at least the revolution count value and a revolution sector value are stored in the non-volatile data memory, with the revolution sector value indicating one of several defined revolution sectors into which a complete revolution is divided for evaluation purposes. The revolution sectors are defined in such a way that they each contain exactly one trigger angle position, i.e., each contain exactly one angular position at which a Wiegand voltage pulse is generated in the Wiegand sensor either during a rotational movement in the positive direction or during a rotational movement in the negative direction.Since the Wiegand voltage pulses are generated at different angular positions during a rotational movement in the positive direction of rotation and during a rotational movement in the negative direction of rotation, at least eight rotation sectors can be distinguished according to the invention, and a complete rotation is therefore divided into at least eight rotation sectors according to the invention for evaluation purposes.

[0015] According to the invention, the evaluation device is designed, when an external power supply is present, to determine a current rotation sector value based on current output signals from the Wiegand sensor and the magnetic field sensor, as well as the stored rotation sector value. Preferably, based on the current output signals from the Wiegand sensor and the magnetic field sensor, a pulse polarity value, which indicates the polarity of the respectively generated Wiegand voltage pulse, and a magnetic pulse value, which indicates whether or not a magnetic field was detected by the magnetic field sensor at the time of the Wiegand voltage pulse, are determined in a manner known from the prior art. The pulse polarity value and the magnetic pulse value form the last two bits of the rotation sector value in binary coded form.Since, according to the invention, at least eight different revolution sector values ​​must be distinguishable, the bit sequence of the revolution sector value must comprise at least one additional bit. The at least one additional bit preferably represents a count value that, based on a defined counting logic, is either increased or decreased by one or remains unchanged, depending on the stored revolution sector value, the current pulse polarity value, and the current magnetic pulse value. According to the invention, the evaluation device is further configured, when an external power supply is present, to either increase or decrease the stored revolution count value or leave it unchanged, based on a defined revolution counting logic, depending on the stored revolution sector value and the current revolution sector value.The revolution counting logic is designed such that the revolution count is increased by one if it can be deduced from the stored revolution sector value and the current revolution sector value that the zero angle position has been crossed in the positive direction of rotation, that the revolution count is decreased by one if it can be deduced from the stored revolution sector value and the current revolution sector value that the zero angle position has been crossed in the negative direction of rotation, and that the revolution count is not changed if it can be deduced from the stored revolution sector value and the current revolution sector value that the zero angle position has not been crossed.

[0016] According to the invention, the evaluation device is further designed, when an external power supply is present, to determine a current absolute position in a known manner based on the stored revolution count value and the current angular position determined by the angular position measuring device, and to store the current revolution sector value in the non-volatile data memory after processing.

[0017] According to the invention, the evaluation device is further designed to carry out a synchronization between the revolution counting device and the angular position measuring device after an interruption of the external power supply by adjusting the revolution count value stored in the non-volatile data memory if necessary.

[0018] In particular, the evaluation device is designed according to the invention to determine a switch-on revolution sector value after an interruption of the external power supply based on the current angular position determined by the angular position measuring device, wherein the switch-on revolution sector value indicates that of the revolution sectors into which a complete revolution is divided for evaluation purposes, in which the current angular position determined by the angular position measuring device lies.

[0019] According to the invention, the evaluation device is further designed, based on a defined synchronization logic, to either increase or decrease the determined current absolute position or leave it unchanged after an interruption of the external power supply, depending on the determined switch-on revolution sector value and the revolution sector value stored in the non-volatile data memory. The synchronization logic is designed such that, upon determining the current absolute position, the revolution count is increased by one if it can be deduced from the switch-on revolution sector value and the stored revolution sector value that the zero angle position was traversed in the positive direction of rotation during the interruption of the external power supply, that upon determining the current absolute position, the revolution count is decreased by one,If it can be deduced from the switch-on revolution sector value and the stored revolution sector value that the zero-angle position was traversed in the negative direction of rotation during the interruption of the external power supply, and if it can be deduced from the switch-on revolution sector value and the stored revolution sector value that the zero-angle position was not traversed during the interruption of the external power supply. Alternatively, the synchronization logic can also be designed such that, instead of increasing, decreasing, or not changing the revolution count when determining the current absolute position, a previously determined current absolute position is increased by one full revolution, decreased by one full revolution, or not changed.

[0020] The absolute rotary encoder according to the invention thus enables the determination of a correct current absolute position after an interruption of the external power supply, without having to separately detect the magnetization state of the Wiegand wire by energizing a coil surrounding the Wiegand wire of the Wiegand sensor. This enables the realization of an absolute rotary encoder for detecting the rotary motion of a shaft that operates reliably even after an interruption of the external power supply and can be manufactured relatively inexpensively.

[0021] In a preferred embodiment, the permanent-magnet rotor unit comprises a rotor plate and at least four permanent magnets attached to the rotor plate, allowing the permanent-magnet rotor unit to be manufactured relatively cost-effectively. Furthermore, the coding element of the angular position measuring device can also be arranged on the rotor plate, so that no additional support element needs to be provided for the coding element of the angular position measuring device. The permanent-magnet rotor unit is preferably designed such that the magnetic field generated by the permanent-magnet rotor unit in the assembled state during a uniform rotational movement of the shaft at the location of the Wiegand sensor alternates exactly four times per revolution. This enables the realization of a permanent-magnet rotor unit that can be manufactured particularly cost-effectively.

[0022] Preferably, the permanent-magnet rotor unit is designed to be mounted on an outer circumferential surface of the shaft, so that the permanent-magnet rotor unit can be mounted on both a solid shaft and a hollow shaft. This allows for the realization of a particularly versatile absolute encoder.

[0023] In a preferred embodiment, the magnetic field sensor is a so-called TMR sensor, which is relatively inexpensive and requires only a relatively low electrical energy for its operation.

[0024] Preferably, the absolute encoder is designed such that, in the assembled state, the Wiegand sensor and / or the magnetic field sensor are arranged axially adjacent to the permanent magnet rotor unit. This allows the realization of an absolute encoder that requires only a relatively small radial installation space.

[0025] Preferably, the angular position measuring device is a capacitive angular position measuring device, which requires only a relatively low electrical energy for its operation. Capacitive angular position measuring devices comprise at least two asymmetrically shaped electrodes, which are designed such that a rotation of the electrodes relative to each other changes the electrical capacitance between the two electrodes. An embodiment of the present invention is described below with reference to the attached figures. Herein:

[0026] Fig. 1 shows a schematic sectional view of an absolute encoder according to the invention for detecting a rotary movement of a shaft,

[0027] Fig. 2 schematically shows an evaluation device and a

[0028] Data interface of the absolute encoder from Fig. 1,

[0029] Fig. 3 schematically shows a rotor unit of the absolute encoder from Fig. 1, wherein different angular positions of the rotor unit are indicated by the respective position of a Wiegand sensor arranged on the stator unit,

[0030] Fig. 4 Bit sequences of distinguishable states of revolution sector values ​​processed by an evaluation device of the absolute encoder from Fig. 1,

[0031] Fig. 5 shows in tabular form a partial revolution counting logic stored in the evaluation device of the absolute rotary encoder from Fig. 1 for determining a partial revolution count value of the bit sequences of the revolution sector values ​​from Fig. 4,

[0032] Fig. 6 shows in tabular form a revolution counting logic stored in the evaluation device of the absolute encoder from Fig. 1 for determining the revolution count value when an external power supply is present, and

[0033] Fig. 7 shows in tabular form a synchronization logic stored in the evaluation device of the absolute rotary encoder from Fig. 1 for determining the revolution count value after an interruption of the external power supply.

[0034] Fig. 1 schematically shows an absolute rotary encoder 100 according to the invention for detecting a rotary movement of a shaft 101 in the assembled state, wherein the shaft 101 is designed as a hollow shaft and is driven by a drive motor 102.

[0035] The absolute rotary encoder 100 comprises an annular disk-shaped rotor plate 1 which radially encloses the shaft 101 and which is directly attached to an outer circumferential surface 101.1 of the shaft 101 and consequently rotates with the shaft 101.

[0036] The absolute rotary encoder 100 further comprises a stator board 2, which is fastened to a housing 102.1 of the drive motor 102 via a plurality of fastening means 103 and is consequently arranged stationary with respect to the shaft 101.

[0037] The absolute value rotary encoder 100 further comprises a magnet-based revolution counter 3 for determining a current revolution count value U, wherein the revolution counter 3 has a Wiegand sensor 3.1, a magnetic field sensor 3.2 designed as a TMR sensor and a permanent-magnet rotor unit 3.3, which is formed by the rotor board 1 and four permanent magnets 3.3.1 - 3.3.4 attached to the rotor board 1.

[0038] The Wiegand sensor 3.1 and the magnetic field sensor 3.2 are arranged axially adjacent to the permanent magnet rotor unit 3.3 on the stator board 2, with the Wiegand sensor 3.1 and the magnetic field sensor 3.2 being arranged adjacent to each other in the circumferential direction of the shaft 101. The Wiegand sensor 3.1 is arranged such that a Wiegand wire 3.1.1 of the Wiegand sensor 3.1 extends in a radial direction of the shaft 101.

[0039] The permanent magnets 3.3.1 - 3.3.4 are designed as diametrically magnetized disc magnets and are arranged on the rotor plate 1 in such a way that their magnetization direction extends essentially parallel to a radial direction of the shaft 101, i.e. in such a way that the magnetic poles N, S are each arranged adjacent in the radial direction, wherein adjacent excitation magnets 1.2a - 1.2d in the circumferential direction of the shaft 101 have opposite magnetization directions.

[0040] Consequently, during a uniform rotational movement of the shaft 101, the permanent magnetic rotor unit 3.3 generates a magnetic field at the location of the Wiegand sensor 3.1, which field alternates exactly four times per revolution of the shaft 101, i.e. changes its polarity exactly four times.

[0041] The absolute rotary encoder 100 further comprises a capacitive angular position measuring device 4 for determining a current angular position W, wherein the angular position measuring device 4 has a rotor electrode arrangement 4.1 arranged around the shaft 101 on the rotor plate 1, a stator electrode arrangement 4.2 arranged around the shaft 101 on the stator plate 2, and measuring electronics 4.3 arranged on the stator plate 2.

[0042] The absolute value rotary encoder 100 further comprises an evaluation device 5, which has a non-volatile data memory 5.1 designed as an FRAM, in which the current revolution count value U and a revolution sector value US-g are stored, and a computing unit 5.2, in which a partial revolution counting logic 5.2.1, a revolution counting logic 5.2.2, a synchronization logic 5.2.3 and an absolute position determination logic 5.2.4 are stored.

[0043] The absolute encoder 100 further comprises a data interface 6, via which data of the absolute encoder 100, in particular a determined current absolute position AP, can be read out externally.

[0044] The stored revolution sector value US-g as well as a current revolution sector value US-a determined as described below and a switch-on revolution sector value US-e determined as described below are each 3-bit values, wherein the last bit represents a pulse polarity value PP, the middle bit represents a magnetic pulse value MP, and the first bit represents a partial revolution count value TW.

[0045] The revolution sector values ​​US-g, US-a, US-e, hereinafter referred to as US in the general case, can each assume the eight different states Pl - P4, NI - N4 shown in Fig. 4 with the bit sequences also shown in Fig. 4, whereby each state is assigned a unique angular position range with a width of 360° / 8 = 45°.

[0046] Each of the states Pl - P4, NI - N4 is here - as shown schematically in Fig. 3 - assigned to a trigger angle position, i.e. an angular position of the permanent magnetic rotor unit 3.3 at which a Wiegand voltage pulse is generated in the Wiegand sensor 3.1, wherein the states Pl - P4 correspond to trigger angle positions during a rotation in a positive direction of rotation Dp and the states NI - N4 correspond to trigger angle positions during a rotation in a negative direction of rotation Dn opposite to the positive direction of rotation Dp.

[0047] For the sake of simplicity, in Fig. 3 the different triggering angle positions of the permanent magnetic rotor unit 3.3 are represented by a rotation of the Wiegand sensor 3.1 and the magnetic field sensor 3.2 opposite to the respective direction of rotation Dp, Dn starting from a zero angle position WO, a rotation of the permanent magnetic rotor unit 3.3 in the positive direction of rotation Dp is thus represented by a rotation of the Wiegand sensor 3.1 and the magnetic field sensor 3.2 in the negative direction of rotation Dn and vice versa.

[0048] The evaluation device 5 is designed, in the presence of an external power supply, to determine in a known manner based on output signals of the Wiegand sensor 3.1 and the magnetic field sensor 3.2 a current pulse polarity value PP, which indicates a polarity of the last Wiegand voltage pulse generated in the Wiegand sensor 3.1, and a current magnetic pulse value MP, which indicates whether or not a magnetic field was detected by the magnetic field sensor 3.2 at the time of the Wiegand voltage pulse.

[0049] The evaluation device 5 is further designed to determine a current rotation sector value US-a based on the stored rotation sector value US-g, the current magnetic pulse value MP and the current pulse polarity value PP when an external energy supply is present.

[0050] Based on the partial revolution counting logic 5.2.1 shown in table form in Fig. 5, a decision is made as to whether the partial revolution count TW of the stored revolution sector value US-g must be increased by one (+1) or decreased by one (-1) or not changed (0) depending on the stored revolution sector value US-g, whether the current partial revolution count TW and consequently the current revolution sector value US-a resulting from the current partial revolution count TW, the current magnetic pulse value MP and the current pulse polarity value PP are determined.

[0051] The evaluation device 5 is further designed, when an external power supply is present, based on the revolution counting logic 5.2.2 shown in a table in Fig. 6, depending on the stored revolution sector value US-g and the previously determined current revolution sector value US-a, to either increase the revolution counting value U stored in the non-volatile data memory 5.1 by one (+1) or decrease it by one (-1) or leave it unchanged (0).

[0052] The evaluation device 5 is further designed, when an external power supply is present, to determine a current absolute position AP by means of the absolute position determination logic 5.2.4 in a known manner based on the stored revolution count value U and the current angular position W determined by the angular position measuring device 4, which can then be read out via the data interface 6.

[0053] The evaluation device 5 is further configured to store the current revolution sector value US-a in the non-volatile data memory 5.1 after processing when an external power supply is present, i.e., to replace the stored revolution sector value US-g with the current revolution sector value US-a. The evaluation device 5 is further configured to perform synchronization between the revolution counter 3 and the angular position measuring device 4 after an interruption of the external power supply.

[0054] The evaluation device 5 is specifically designed to determine a switch-on revolution sector value US-e after an interruption of the external voltage supply based on the current angular position W determined by the angular position measuring device 4 by checking in which of the angular position ranges assigned to the eight states Pl - P4, NI - N4 the current angular position W lies.

[0055] The evaluation device 5 is further specifically designed, after an interruption of the external voltage supply, based on the synchronization logic 5.2.3 shown in tabular form in Fig. 7, depending on the previously determined switch-on revolution sector value US-e and the revolution sector value US-g stored in the non-volatile data memory 5.1, to either increase the current absolute position AP previously determined by means of the absolute position determination logic 5.2.4 by one full revolution (+1) or to decrease it by one full revolution (-1) or to leave it unchanged (0) or to increase the stored revolution count value U by one (+1) or to decrease it by one (-1) or to leave it unchanged (0) when determining the current absolute position AP.

[0056] List of reference symbols

[0057] 100 absolute encoders

[0058] 1 rotor board

[0059] 2 Stator board

[0060] 3 revolution counter

[0061] 3.1 Wiegand sensor

[0062] 3.1.1 Wiegand wire

[0063] 3.2 Magnetic field sensor

[0064] 3.3 permanent magnetic rotor unit

[0065] 3.3.1 Permanent magnet

[0066] 3.3.2 Permanent magnet

[0067] 3.3.3 Permanent magnet

[0068] 3.3.4 Permanent magnet

[0069] 4 Angular position measuring device

[0070] 4.1 Rotor electrode arrangement

[0071] 4.2 Stator electrode arrangement

[0072] 4.3 Measuring electronics

[0073] 5 Evaluation device

[0074] 5.1 non-volatile data storage

[0075] 5.2 Computing unit

[0076] 5.2.1 Partial revolution counting logic

[0077] 5.2.2 Revolution counting logic

[0078] 5.2.3 Synchronization logic

[0079] 5.2.4 Absolute position determination logic

[0080] 6 Data interface

[0081] 101 Wave

[0082] 101.1 Outer peripheral surface

[0083] 102 drive motor

[0084] 102.1 Housing 103 Fasteners

[0085] AP absolute position

[0086] Dn negative direction of rotation Dp positive direction of rotation

[0087] MP magnetic pulse value

[0088] P1-P4 rotation sector values ​​for positive direction of rotation

[0089] N1-N4 rotation sector values ​​for negative direction of rotation

[0090] PP Pulse polarity value TW Partial revolution count value

[0091] U Revolution count

[0092] US-a current revolution sector value

[0093] US-g stored revolution sector value

[0094] US-e Switch-on revolution sector value W Angular position

[0095] WO zero angle position

Claims

PATENT CLAIMS 1. Absolute value rotary encoder (100) for detecting a rotary movement of a shaft (101), comprising: a revolution counting device (3) for determining a revolution count value (U), with - a Wiegand sensor (3.1), - a magnetic field sensor (3.2), and - a permanent-magnetic rotor unit (3.3) which is designed to be mounted so as to rotate with the shaft (101) and which is designed such that, in the mounted state, the permanent-magnetic rotor unit (3.3) generates a magnetic field alternating at least four times per revolution during a uniform rotational movement of the shaft (101) at the location of the Wiegand sensor (3.1), an angular position measuring device (4) for determining a current angular position (W) of the shaft (101), and an evaluation device (5) with a non-volatile data memory (5.1) in which the revolution count value (U) and a revolution sector value (US-g) are stored, wherein the evaluation device (5) is designed, when an external power supply is present: - to determine a current revolution sector value (US-a) based on the output signals of the Wiegand sensor (3.1) and the magnetic field sensor (3.2) as well as the stored revolution sector value (US-g), - depending on the stored revolution sector value (US-g) and the current revolution sector value (US-a), to either increase or decrease the stored revolution count value (U) or to leave it unchanged, - to determine a current absolute position (AP) based on the stored revolution count value (US-g) and the current angular position (W) determined by the angular position measuring device (4), and - to store the current revolution sector value (US-a) after processing in the non-volatile data memory (5.1), and wherein the evaluation device (5) is designed, after an interruption of the external power supply: - to determine a switch-on revolution sector value (US-e) based on the current angular position (W) determined by the angular position measuring device (4), and - depending on the determined switch-on revolution sector value (US-e) and the stored revolution sector value (US-g), the determined current absolute position (AP) is either increased or decreased or left unchanged.

2. Absolute rotary encoder (100) according to claim 1, wherein the permanent magnetic rotor unit (3.3) comprises a rotor board (1) and at least four permanent magnets (3.3.1 - 3.3.4) attached to the rotor board (1).

3. Absolute rotary encoder (100) according to one of the preceding claims, wherein the permanent-magnetic rotor unit (3.3) is designed such that the magnetic field generated by the permanent-magnetic rotor unit (3.3) in the assembled state alternates exactly four times per revolution during a uniform rotational movement of the shaft (101) at the location of the Wiegand sensor (3.1).

4. Absolute encoder (100) according to one of the preceding Claims, wherein the permanent magnetic rotor unit (3.3) is designed to be mounted on an outer peripheral surface (101.1) of the shaft (101).

5. Absolute rotary encoder (100) according to one of the preceding claims, wherein the magnetic field sensor (3.2) is a TMR sensor.

6. Absolute encoder (100) according to one of the preceding Claims, wherein the Wiegand sensor (3.1) and / or the magnetic field sensor (3.2) is arranged axially adjacent to the permanent magnet rotor unit (3.3).

7. Absolute rotary encoder (100) according to one of the preceding claims, wherein the angular position measuring device (4) is a capacitive angular position measuring device.

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