DE102012017071A1 - Energy self-sufficient multiturn-rotary encoder for determining number of complete three hundred sixty degree rotations of encoder shaft, has excitation magnet and optical code disk to determine absolute rotary angle - Google Patents

Abstract

The energy self-sufficient multiturn-rotary encoder (10) has an excitation magnet (16) that is fixed in a torque-proof manner for generating an external magnetic field (40), where an optical code disk is fixed for determining an absolute rotary angle. The rotary angle indicates a finely resolved position within 360 degree-rotation of an encoder shaft (18). A single impulse sensor (12) is provided for generation of energy from a magnetization reversal impulse. A history storage is provided for storing the history of quadrant values. An independent claim is included for a method for determining a unique position of an encoder shaft.

Description

The present invention relates to a multi-turn rotary encoder (hereinafter also referred to for short as "MT rotary encoder") for detecting both a fine resolution position (absolute angle within a 360 ° revolution) and a number of complete or complete 360 ° rotation. Turns (revolution count). Moreover, the invention relates to a method for determining a unique position of a encoder shaft which rotates about a rotation axis, by means of the energy self-sufficient multi-turn encoder, which is adapted to detect the number of complete 360 ° revolutions of the rotating encoder shaft and for detecting an absolute angle of rotation indicating a finely resolved position within the 360 ° rotation of the encoder shaft, wherein on the encoder shaft, a field magnet for generating an external magnetic field is rotationally fixed, which can be used at least for a determination of the fine resolution position.

There are known mechanical MT rotary encoders (eg DE 196 26 654 A1 ), in which several Winkelcodierscheiben are connected to each other via a reduction gear. Each subsequent Winkelcodierscheibe is rotated at a complete revolution of an upstream Winkelcodierscheibe to a unit corresponding to their resolution capacity. In this type of encoder multiplied according to the number of Codierscheiben also a number of sampling systems. For the reduction gear high precision is required. This type of encoder can only be laboriously assembled. The reduction gear is not wear-free and allows only limited speeds.

MT rotary encoders with an electronic counting unit are also known (eg. EP 0 516 572 B1 ), in which instead of the mechanical transmission, an additional coding disc is used, which is directly connected to the encoder shaft and which serves to detect the number of revolutions of the encoder shaft. A code located on this additional coding disc is optically read out and converted into counting pulses, which are forwarded to a counting unit. To buffer corresponding data, a battery or a battery is housed together with the counter unit in the rotary encoder. Since the permanent optical readout of the Codierscheiben relatively high power needs, because a light source must be constantly energized in this readout, in order not to lose data, the batteries or batteries are relatively large. Therefore, the encoder itself also has a corresponding size when a battery or a battery is to be used, which requires a useful data buffering time of typically several years. Furthermore, such an optical system is also unsuitable for certain hard applications where high mechanical shocks occur or where condensation-inducing climatic conditions prevail.

Furthermore, revolution counters are known, which convert a kinetic energy of the wave motion into electrical energy at a switched off external supply voltage and feed it at least the revolution counter electrically. Such a method, in which kinetic energies are converted into electrical energy, based on the so-called Wiegand effect. Such a revolution counter is among others in the DE 10 259 223 B3 shown. The DE 10 259 223 B3 shows an energy self-sufficient revolution counter based on a Wiegand sensor. In this known solution, only a Wiegand sensor and a dipole magnet are used as the excitation magnet. In addition, a specific low-power Hall sensor or a second induction coil must be used to determine a polarity of the external magnetic field. In addition, additional additional flux guides are used. These measures make the system more expensive DE 10 259 223 B3 considerably. The Hall sensor is a complex circuit that typically exhibits a relatively long settling time to full operational readiness after a pulse is triggered in the Wiegand sensor. During this time, however, part of the energy generated by the so-called Wiegand pulse is lost, for example in the form of leakage currents. The DE 10 259 223 B3 does not show a detailed overall solution for a revolution counter with a fine-resolution single-turn sensor (also referred to below as "ST sensor" for short).

The document DE 34 08 478 C1 shows a magneto-inductive incremental encoder, which is self-sufficient with so-called Wiegand or impulse wires. In a rotation of these wires on the outer circumference of a (encoder) shaft to which a field magnet is attached, these wires are moved past the magnet, so that a sudden remagnetization of the pulse wires is effected. This remagnetization induces a corresponding voltage in a coil surrounding the pulse wires. By counting the Wiegand or magnetic reversal pulses, an angular position (absolute angle of rotation) and the number of complete 360 ° revolutions can be determined. However, this system does not provide an absolute position when switched on for the first time.

An absolute MT rotary encoder with an ST function (360 ° resolving system) shows the EP 0 231 474 B1 , The MT rotary encoder is coupled with an energy self-sufficient, revolution counter. This means that sensors that capture whole 360 ° revolutions are suitable, do not need to be powered externally with energy. However, a disadvantage of this system is, on the one hand, a required battery for buffering the data, while an external supply voltage is switched off. On the other hand, the relatively high sensory effort in the form of three Wiegand sensors is disadvantageous. A circuit needed to synchronize the ST with the MT is relatively expensive in this arrangement.

One opposite the EP 0 231 474 B1 improved solution of the aforementioned type shows the DE 44 07 474 C2 , In the DE 44 07 474 C2 No battery is needed, as the energy that the Wiegand sensors emit in pulses is used both for detecting and counting whole revolutions and for backing up the data in an FRAM memory. However, the other disadvantages also remain here, in particular the fact that several Wiegand wires and / or magnets are used.

In general, there is the problem with the conventional solutions that a clear guidance is missing, as the sensors for detecting the absolute rotation angle with the sensors for detecting the complete revolutions with the least possible effort can be synchronized with each other. In the DE 10 259 223 B3 In addition, the Hall sensor and the Wiegand sensor must be arranged at a certain angle to each other, which increases assembly costs and jeopardizes reliable operation of the system over a wide temperature range in temperature variations of the magnet, the Hall sensor and / or the Wiegand sensor.

It is therefore an object of the present invention to provide an integrated solution which specifies a finely resolving singleturn and a multiturn for counting complete 360 ° revolutions including a suitable synchronization method, which ensures that the mutually non-synchronous zero crossings of the single turn (ST ) and the multiturn (MT).

This object is achieved by an energy-autonomous multi-turn encoder for detecting a number of complete 360 ° revolutions of a sensor shaft which rotates about an axis of rotation and to which an excitation magnet for generating an external magnetic field is non-rotatably attached, and on which an optical encoder for detection an absolute angle of rotation is fixed, which indicates a finely resolved position within a 360 ° rotation of the encoder shaft, wherein the multi-turn encoder for energy self-detecting the number of complete 360 ° revolutions of the encoder shaft comprises: a, preferably single, pulse sensor for generating Energy from a remagnetization pulse caused in the pulse sensor by a sufficiently large change in a magnitude of the external magnetic field, the magnetic field strength change being caused by a rotation of the exciter magnet; a, preferably single, optical sensor for detecting a current position of the encoder shaft and for generating a corresponding signal whose signal value corresponds to the current position of the encoder shaft and is available to the evaluation unit, wherein the signal has a, preferably sinusoidal course when the Exciter magnet continuously rotates with the encoder shaft about the axis of rotation, and the course is evaluated logically divided into a plurality of, preferably equal to, quadrants; a revolution counter to Storing the number of complete 360 ° revolutions of the encoder shaft; a history memory in which a history of quadrant values is storable; and an evaluation unit, which is exclusively operated to determine the number of complete 360 ° revolutions of the encoder shaft with energy obtained from the Ummagnetisierungsimpulsen; wherein the evaluation unit is adapted to derive from the supplied signal value one of the quadrants in which the supplied signal value lies, and to supply a corresponding quadrant value to the history memory, while one of the remagnetization pulses occurs.

Further, an energy self-sufficient multi-turn encoder for detecting a number of complete 360 ° revolutions of a encoder shaft is disclosed which rotates about a rotation axis and on which a field magnet for generating an external magnetic field is rotationally fixed, and for determining an absolute angle of rotation, a finely resolved position indicates within a 360 ° rotation of the encoder shaft, wherein the multi-turn encoder for energy self-detecting the number of complete 360 ° revolutions of the encoder shaft has a, preferably single, pulse sensor for generating energy from a Ummagnetisierungsimpuls in the pulse sensor by a sufficiently large Change of a strength of the external magnetic field is caused, wherein the magnetic field strength change is caused by a rotation of the exciter magnet, further a, preferably single, magnetic field sensor for detecting the strength of the external magnetic field and for generating a corresponding the signal whose signal value corresponds to the strength of the external magnetic field and is available to the evaluation unit, wherein the signal ideally has a sinusoidal course, when the exciter magnet rotates continuously with the encoder shaft about the axis of rotation, and wherein the sinusoidal waveform evaluation logically into a plurality is divided by, preferably equal-sized, quadrants, further comprising a revolution counter for storing the number of complete 360 ° revolutions of the encoder shaft, further comprising a history memory in which a history of quadrant values can be stored and further comprising an evaluation unit for determining the number of completely completed 360 ° revolutions of the encoder shaft is operated exclusively with energy obtained from the Ummagnetisierungsimpulsen, wherein the evaluation unit is adapted to derive from the supplied signal value of the quadrant, in which m is the supplied signal value, and to provide a corresponding quadrant value to the history memory, while one of the Ummagnetisierungsimpulse occurs.

According to a preferred embodiment, the pulse sensor is a Wiegand sensor.

In an advantageous embodiment, the magnetic field sensor is high-eared and is an xMR element, in particular a TMR, AMR or GMR element.

Furthermore, it is preferred if the multiturn rotary encoder has a rectifier.

In particular, the exciter magnet may be a permanent magnet, in particular a dipole, which is preferably fastened centrically to the encoder shaft.

Preferably, the pulse sensor and the magnetic field sensor are arranged coaxially with the encoder shaft and the exciter magnet so that the pulse sensor and the magnetic field sensor are spaced apart from the exciter magnet in the axial direction when the encoder shaft is assembled with the multi-turn encoder.

In accordance with another preferred embodiment, n remagnetization pulses may be generated for each of the 360 ° revolutions of the encoder wave, and every nth remagnetization pulse of a pulse cycle may cause an update of a value of the revolution counter memory.

In an advantageous embodiment, an orientation of the magnetic field sensor relative to the pulse wire is selected so that the Ummagnetisierungsimpulse each lie substantially centrally in the corresponding quadrant.

Furthermore, it is preferred if the multiturn rotary encoder has an energy store which is electrically connected to the pulse sensor and which is charged only with energy which is obtained from the remagnetization pulses. Furthermore, this object is achieved by a method for determining a unique position of a sensor shaft which rotates about a rotation axis, by means of an energy-self-sufficient multi-turn encoder, for the optical detection of a number of complete 360 ° revolutions of the rotating encoder shaft and for the optical detection of a absolute rotation angle is set, which indicates a finely resolved position within a 360 ° rotation of the encoder shaft to which an excitation magnet for generating an external magnetic field is non-rotatably attached, which is used to generate an energy that is required for the revolution count, wherein the multiturn rotary encoder has a pulse sensor, an optical sensor, a revolution counter, a history memory and an evaluation unit, wherein the optical sensor delivers a signal with a, preferably sinusoidal, course, when the encoder shaft rotates continuously about the axis of rotation and wherein the course evaluation logic is divided into a plurality of, preferably equal-sized, quadrants, the method comprising the following steps: providing an evaluation energy at a time t1 when a Ummagnetisierungsimpuls is generated in the pulse sensor; Activating the evaluation unit and the optical sensor at a time t2 immediately after the evaluation energy is ready; thereafter detecting an optical value generated by illuminating the encoder disk and outputting a corresponding signal; Determining and outputting by the evaluation unit a current quadrant corresponding to the output signal in which the magnetic reversal pulse has taken place; Activating the memory element and updating a quadrant history having last stored quadrant values; and deactivating the evaluation unit after all the aforementioned steps have been performed and before the remagnetization pulse decays.

Further, a method for detecting a unique position of a donor shaft rotating about a rotation axis is disclosed by means of a self-powered multi-turn rotary encoder arranged to detect a number of full 360 ° revolutions of the rotating donor shaft and to detect an absolute rotation angle, indicating a finely resolved position within a 360 ° rotation of the encoder shaft to which an excitation magnet for generating an external magnetic field is non-rotatably mounted, which is used at least for a determination of the fine resolution position, the multi-turn encoder a pulse sensor, an energy storage , a magnetic field sensor, a revolution counter, a history memory and an evaluation unit, wherein the magnetic field sensor provides a signal with an ideal sinusoidal course, when the exciter magnet rotates continuously with the encoder shaft about the axis of rotation and wherein the sinusoidal History is divided into a plurality of, preferably equal, quadrants, the method comprising the steps of: storing a history of quadrants in the history memory, each quadrant value a Ummagnetisierungsimpulsuls in the pulse sensor by a specific change of the external magnetic field due to rotation the encoder shaft is triggered, and where each quadrant value is determined by the evaluation unit taking into account a signal value supplied by the magnetic field sensor due to the Ummagnetisierungsimpulses to the evaluation and is supplied to the history memory, where n Ummagnetisierungsimpulse for each of the 360 ° revolutions of the Encoder shaft are generated and wherein each n-th magnetic reversal pulse an update of the revolution counter in the form of a rotational sense-dependent incrementing or decrementing a value of the revolution counter by the evaluation unit and during a period of time comprising a discrete time for which the unique position of the encoder shaft is to be determined, performing the following steps: providing the evaluation unit and the magnetic field sensor with an external energy, detecting a strength of the external magnetic field at the discrete time by means of the magnetic field sensor and supplying the corresponding signal value to the evaluation unit, determining by means of the evaluation unit, in which the quadrant of the supplied signal value is queries of the last quadrant value, which was stored in the history memory last in the history, by the evaluation unit, checking by the evaluation unit whether the delivered signal value is within a forbidden quadrant zone associated with the last stored quadrant value, wherein for each quadrant value, a specific forbidden quadrant zone is pre-determined and stored when the supplied sig nal value outside the forbidden quadrant zone, determining the unique position by summing the absolute angle of rotation corresponding to the supplied signal value with a current revolution counter value, or otherwise if the supplied signal value is within the forbidden quadrant zone, evaluating an additional signal additionally provided by the pulse sensor is generated, correcting the revolution counter value by means of the evaluation unit based on the additional signal and determining the absolute rotation angle based on the additional signal before the unique position of the absolute rotation angle and the corrected revolution counter value is determined.

Preferably, the specific forbidden quadrant zones are stored in a memory of the evaluation unit or in a separate memory element.

Further preferably, the pulse sensor comprises a, preferably single, pulse wire and a, preferably single, coil surrounding the pulse wire, the pulse wire having an outer jacket and a core disposed inside the jacket.

Furthermore, it is preferable that outer boundaries of the forbidden quadrant zones are defined by core remagnetization ignition thresholds.

According to a preferred embodiment, the pulse sensor comprises a, preferably single, pulse wire and a, preferably single, coil surrounding the pulse wire, and wherein the step of evaluating the auxiliary signal and correcting the revolution counter value comprises: energizing the coil for a short period of time; such that an external magnetic field is superimposed on the external magnetic field of the excitation magnet and a test remagnetization pulse can be generated in the pulse wire, which is then measurable with the coil, an existence or nonexistence of the test remagnetization pulse being supplied as the additional signal from the coil to the evaluation unit checking, by the evaluation unit, whether the additional signal contains the test remover pulse or not, and correcting the value of the revolution counter if the additional signal contains the test remover pulse, or keeping the current revolution counter value if the set signal does not contain the test remagnetization pulse.

In an advantageous embodiment, the step of correcting the value of the revolution counter comprises a rotation-dependent incrementing or decrementing of the value of the current revolution counter.

Further, it is preferred that the pulse sensor comprises a first pulse wire, at least one second pulse wire, a bobbin in which the pulse wires are arranged, and a, preferably single, coil which in turn surrounds the bobbin, each of the pulse wires having an outer jacket and a core disposed within the shell and wherein the pulse wires are fixed in a respective predetermined position in the winding body.

According to a preferred embodiment, outer boundaries of the respective forbidden quadrant zone are defined by remagnetization ignition thresholds of the cores.

According to a further preferred embodiment, the remagnetization pulses of the second pulse wire are used as additional signal.

Furthermore, it is preferred if the pulse wires are spaced apart in the axial direction of the encoder shaft, and are preferably arranged axially parallel to each other.

Preferably, the pulse wires are arranged in a single plane oriented substantially perpendicular to the axis of rotation of the encoder shaft, and wherein the first pulse wire subtends an angle with each of the second pulse wires.

In a further advantageous embodiment, the pulse sensor is arranged coaxially to the exciter magnet, wherein the pulse wires are arranged in at least one plane which is oriented in each case substantially perpendicular to the axis of rotation of the encoder shaft and substantially parallel to the plane of rotation of the exciter magnet.

Furthermore, it is preferred if the excitation magnet is a single dipole magnet, which is arranged in a plane which is oriented substantially perpendicular to the axis of rotation.

Preferably, the pulse sensor is arranged eccentrically to the axis of rotation of the encoder shaft, wherein in addition to the coaxially arranged exciter magnet at least four additional magnets are provided which are evenly distributed in the circumferential direction with alternating magnetic fields fixed to the encoder shaft, so that in each quadrant at least one Ummagnetisierungsimpuls is generated Such Ummagnetisierungsimpulse, which differ from the usual Ummagnetisierungsimpulsen, provide the additional signal.

Further preferably, the number of additional magnets is defined by 2 ⁿ , where n is an integer number greater than 2.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Show it:

1 a multi-turn encoder;

2 different states of a pulse wire ( 2A ) and a table of impulse variants ( 2 B )

3 a block diagram of the encoder of the 1 ;

4 a course of a magnetic field, which is generated by a non-rotatably connected to a donor shaft exciter magnet ( 4A ) and a sine and a cosine output signal of an xMR element ( 4B );

5 critical points in a waveform without directional changes;

6 critical points in a signal course with direction change incl. undefined zones;

7 Flow diagrams of a method for determining a unique position of a encoder shaft;

8th a side view ( 8A ) and a cross section ( 8B ) of a multi-wire pulse wire sensor;

9 a side view ( 9A ) and a cross section ( 9B ) another pulse wire sensor having a plurality of wires;

10 a top view ( 10A ) on a MT rotary encoder with additional magnets, a signal course without change of direction ( 10B ) and a waveform with direction change ( 10C );

11 a top view ( 11A ) to another MT rotary encoder with additional magnets, a signal course without change of direction ( 11B ) and a waveform with direction change ( 11C );

12 a plan view of yet another MT rotary encoder;

13 a construction of an optical MT rotary encoder;

14 a block diagram of the optical MT encoder of 13 ;

15 Sine and cosine output signals of the MT rotary encoder 13 ;

16 a coding disc of the MT rotary encoder of the 13 ;

17 an overview of signals from different function blocks of the MT rotary encoder of 13 ; and

18 a modification of the coding of the 16 ,

1 shows a much simplified representation of an MT rotary encoder 10 , The MT rotary encoder 10 has a pulse wire sensor 12 (eg one Wieganddrahtsensor), a magnetic field sensor (in particular an xMR element 14 ) and an evaluation logic or unit 15 on. The operation of the pulse wire sensor 12 or a Wiegand wire sensor is sufficiently known from the aforementioned documents. In this context, in particular on the DE 34 08 478 C1 directed.

The MT rotary encoder 10 acts with an exciter magnet 16 together, which is preferably designed as a permanent magnet, in particular as a dipole, which on a sensor shaft 18 rotatably attached to the encoder shaft 18 around a rotation axis 19 to rotate. The exciter magnet 16 and the encoder shaft 18 can rotate clockwise or counterclockwise. In the 1 rotates the encoder shaft 18 counterclockwise as it is by one direction of rotation 20 is displayed. The encoder shaft 18 belongs to an external device or couples to the external device, which is not shown here and whose rotation is to be measured. The encoder shaft 18 can by not shown shaft bearing in a housing 22 of the MT rotary encoder 10 be rotatably mounted. Optionally, a so-called "KIT transmitter" is possible, which is not stored and has two components (stator and rotor). The housing 22 is in 1 only partially shown and z. B. with a circuit board 24 about distance bolts 26 be connected. The pulse wire sensor 12 can on a top 28 the circuit board 24 be arranged. The xMR element 14 can on a bottom 30 the circuit board 24 be arranged. It is understood that the pulse wire sensor 12 and the xMR element 14 can exchange their positions or both on the same page 28 or 30 the circuit board 14 can be arranged. The sensor 12 and the element 14 can also be another component of the MT rotary encoder 10 be attached. In the 1 is also an exemplary centric (coaxial) arrangement of the encoder shaft 18 , the exciter magnet 16 , the xMR element 14 and the pulse wire sensor 12 shown. These components 12 - 18 are in an axial direction of the encoder shaft 18 spaced apart from each other. This type of arrangement is particularly advantageous when designed as a dipole permanent magnet as a field magnet 16 used in a rotation plane 32 is arranged and rotates perpendicular to the axis of rotation 19 is oriented. It is understood that the orientation of the plane of rotation 32 easy with a few degrees of a 90 ° orientation relative to the axis of rotation 19 may differ without limiting the operation of the invention described below. The rotation plane 32 is then still substantially perpendicular to the axis of rotation 19 aligned.

In the 1 is also a mounting plane 34 for the sensor 12 and the xMR element 14 shown parallel to the plane of rotation 32 is arranged and through the circuit board 24 runs. Although the orientations include a (small) angle of a few degrees with each other, they are considered to be substantially parallel in the following. The xMR element 14 and the pulse wire sensor 12 are parallel to the mounting plane 34 (PCB 24 ) arranged.

The pulse wire sensor 12 comprises a pulse wire, in particular a Wiegand wire, 36 (hereinafter also referred to as "wire" for short) on top of a coil 38 is surrounded and in the 1 parallel to the mounting plane 34 is arranged. The orientation of the pulse wire sensor 12 depends on the orientation of an external magnetic field 40 that's in the pulse wire 36 generates a magnetic reversal pulse for the exclusive purpose of generating energy and in the xMR element 14 used to determine a field strength and direction. In the 1 becomes the exciter magnet 16 as the only component both for energy generation in the sensor 12 as well as for determining an absolute angle of rotation (ST rotation angle) by means of the element 14 used. The energy is transmitted through the pulse wire sensor 12 won. The absolute rotation angle is determined on the basis of a signal which is in the xMR element 14 is produced. It is understood that a plurality of spatially separated magnets, including multi-pole magnets, can be used to enable the generation of power separately from the determination of the absolute angle of rotation, as will be explained in more detail below. For the sake of a simplified description, it is initially assumed for the time being that only the preferably bipolar exciter magnet 16 is used for both purposes.

The xMR element 14 builds physically on the magnetoresistive effect and is usually realized by a, preferably single, TMR element. The xMR element 14 is a device having two ferromagnetic layers separated by a thin insulator layer. If the insulating layer is thin enough (typically a few nanometers), electrons can "tunnel" between the two ferromagnetic layers. This is a quantum mechanical phenomenon. Essentially, a distinction is made between the anisotropic magnetoresistive effect (AMR effect) and the gigantic magnetoresistive effect (GMR effect). The xMR element 14 can also be realized by a, preferably single, GMR or AMR element.

• – Der Impulsdraht 36 weist üblicherweise einen hartmagnetischen Mantel 46 und einen weichmagnetischen Kern 48 (2A) auf. Der Mantel 46 und der Kern 48 sind unterschiedlich magnetisierbar. Es gibt grundsätzlich drei Magnetisierungskonstellationen, eine mit gleicher Ausrichtung und zwei mit entgegen gesetzten Ausrichtungen. Auf Grund der Formanisotropie haben die Werkstoffe des Mantels 46 und des Kerns 48 jeweils nur einen Weissschen Bezirk und es existieren somit fast rechteckige Hysteresekurven.
• – Der Impulsdraht 36 ist ein bistabiles magnetisches Element.
• – Ein äußeres Magnetfeld bestimmter Stärke (Koerzitivfeldstärke) mit einer dem Impulsdraht 36 entgegengesetzten Magnetisierungsrichtung lässt die Magnetisierungsrichtung des Impulsdrahts 36 schlagartig umklappen (Wiegand-Effekt).
• – Diese magnetische Flussänderung induziert in der Spule 38 einen kurzen, ca. 20 μs langen elektrischen (Ummagnetisierungs-)Impuls.
• – Der Energiegehalt eines solchen Impulses liegt typischerweise im Bereich von 40 bis 150 nWs, abhängig von einer Impulsdrahtlänge, Kennzahlen der Spule 38, Lastwiderständen und dergleichen.
• – Eine Länge des Impulses und ein Energiegehalt des Impulses sind weitestgehend von der Änderungsgeschwindigkeit und der Richtung des externen Magnetfelds 40 unabhängig.
• – Ein ”symmetrischer Betrieb” erzeugt aus der Ummagnetisierung positive und negative Spannungsimpulse in der Spule 38 bei einer Änderung der Polarität und Feldstärke des externen Magnetfelds 40. Der symmetrische Betrieb liegt vor, wenn die externe Magnetfeldstärke 40 ausreicht, zuerst den Kern 48 und danach den Mantel 46 umzumagnetisieren und den Impulsdraht 36 in die magnetische Sättigung zu bringen.
• – Ein ”asymmetrischer Betrieb” erzeugt nur Spannungsimpulse gleichbleibender Polarität bei einer Änderung der Polarität und der Feldstärke des externen Magnetfelds 40. Der asymmetrische Betrieb liegt vor, wenn die Magnetfeldstärke lediglich ausreicht, um den Kern 48 nicht aber den Mantel 46 umzumagnetisieren. Vorliegend wird im Wesentlichen im symmetrischen Betrieb gearbeitet.
• – Ein Wiegand-Sensor besteht aus einem Wiegand-Draht und einer Spule.
• – Als ”Zündfeldstärke”, ”Zündschwelle” oder ”Triggerschwelle” wird nachfolgend eine jeweilige externe Magnetfeldstärke bezeichnet, die erforderlich ist, um den Kern 48 bzw. den Mantel 46 des Drahtes 36 umzumagnetisieren. Nachfolgend wird dies auch als ein ”Umklappen” der Magnetorientierung des Kerns 48 bzw. des Mantels 46 bezeichnet.

For the following description, the following aspects for the impulse wire can be used 36 to be relevant:

• - The pulse wire 36 usually has a hard magnetic shell 46 and a soft magnetic core 48 ( 2A ) on. The coat 46 and the core 48 are different magnetizable. There are basically three magnetization constellations, one with the same orientation and two with opposite orientations. Due to the shape anisotropy, the materials of the jacket have 46 and the core 48 in each case only one Weiss district and thus there are almost rectangular hysteresis curves.
• - The pulse wire 36 is a bistable magnetic element.
• - An external magnetic field of certain strength (coercive force) with a pulse wire 36 opposite magnetization direction leaves the magnetization direction of the pulse wire 36 abruptly fold over (Wiegand effect).
• - This magnetic flux change induces in the coil 38 a short, approximately 20 μs long electrical (remagnetization) pulse.
• - The energy content of such a pulse is typically in the range of 40 to 150 nWs, depending on a pulse wire length, characteristics of the coil 38 , Load resistors and the like.
• - A length of the pulse and an energy content of the pulse are largely of the rate of change and the direction of the external magnetic field 40 independently.
• - A "symmetrical operation" generates positive and negative voltage pulses in the coil from the remagnetization 38 with a change in the polarity and field strength of the external magnetic field 40 , Symmetrical operation occurs when the external magnetic field strength 40 sufficient, first the core 48 and then the coat 46 umumumagnetisieren and the pulse wire 36 into magnetic saturation.
• - An "asymmetrical operation" generates only voltage pulses of constant polarity with a change of the polarity and the field strength of the external magnetic field 40 , Asymmetrical operation is when the magnetic field strength is sufficient only to the core 48 but not the coat 46 umzumagnetisieren. In the present case, work is essentially carried out in symmetrical operation.
• - A Wiegand sensor consists of a Wiegand wire and a coil.
• - As "ignition field strength", "ignition threshold" or "trigger threshold" below a respective external magnetic field strength is referred to, which is required to the core 48 or the coat 46 of the wire 36 umzumagnetisieren. This is also referred to as a "flip" of the magnetic orientation of the core 48 or the coat 46 designated.

Referring to the 2A Subsequently, the above-mentioned "remagnetization" and "folding down of the magnetic orientation (s)" will be described on the basis of three states Z1-Z3 of the wire 36 explained in the form of a longitudinal section through the wire 36 is shown. The coat 46 surrounds the inner core 48 Completely. A magnetic field direction is in the form of arrows 44 in the coat 46 or at the core 48 indicated. In state Z1 is the external magnetic field 40 with his magnetic field lines 42 (see. 1 ) in the same direction as the field direction 44 in the wire 36 oriented. In state Z2, the direction of the outer field has changed 40 turned around and became so strong that the field direction 44 in the core 48 folds over, whereas the strength of the external magnetic field 40 but not enough, even the field direction 44 of the coat 46 to reverse, ie the coat 46 umzumagnetisieren. In state Z3 is the external magnetic field 40 still oriented as in state Z2, but now so strong that even the coat 46 is remagnetized.

2 B shows a table in which possible (Ummagnetisierungs-) pulse variants are shown simplified examples.

Starting in state Z1 leaves the external magnetic field 40 when reaching a certain strength (coercive force of the core) with a wire 36 opposite magnetization direction (ie the outer field 40 is directed from right to left) the magnetization direction 44 of the core 48 abruptly fold over (Wiegand effect). In the coil 38 (see. 1 ) then becomes a large, high-energy (remagnetization) pulse 52 respectively. 52 ' generated as described below with reference to 4A will be explained again, because the core 48 against the field direction of the jacket 46 folded down (variant 1). Would you consider the strength of the external magnetic field 40 then increase continuously so that the orientation of the external magnetic field 40 is maintained and the strength increases, would also coat 46 in the field direction 44 of the core 48 fold over, as shown in state Z3. Folding the coat 46 parallel to the core 48 results in a small magnetic reversal pulse, which is hardly measurable (variant 3). However, reversing the direction of the external magnetic field starting from state Z2 before state Z3 is reached, the core works 48 again in the direction of the coat 46 in the state Z1 back (variant 2), which in a middle Ummagnetisierungsimpuls (in 4A not shown) results, which has a much lower energy than the pulse in the variant 1.

In "symmetrical operation" are through the coil 38 positive and negative voltage pulses with a change in polarity and field strength of the external magnetic field 40 generated. When remagnetizing the core 48 contrary to the magnetic direction, a relatively large momentum arises 52 respectively. 52 ' with high energy content. When folding the jacket 46 - With continued rotation of the exciter magnet 16 in the same direction of rotation - arises only one relatively small impulse (variant 3), which can not be used because of its very low energy content. In variant 2, the core works 48 again in the direction of the coat 46 back, because the direction of rotation of the encoder shaft and thus the polarity of the external magnetic field 40 begins to change before the coat 46 in the direction of the core 48 can fold over (variant 2). Variation 2 represents a rather rare event, which usually only arises if the reversal of the sense of rotation 20 the encoder shaft 18 immediately during or after a magnetic reversal pulse 52 respectively. 52 ' the variant 1 occurs, and that before the state Z3 begins with theoretically continued direction of rotation.

3 shows a block diagram 60 of the MT rotary encoder 10 of the 1 , In a block 62 the energy is generated and optionally stored, which is needed for signal evaluation and processing, in particular for counting 360 ° revolutions. The block 62 can be a rectifier 64 to the Ummagnetisierungsimpulse obtained during a 360 ° rotation 52 respectively. 52 ' that have opposite polarities, all align the same. The by a Ummagnetisierungsimpuls 52 respectively. 52 ' generated energy, which is usually 40 to 150 nWs, can be stored in an energy store 66 (eg in a capacitor 67 ) are buffered. However, the energy gained is extremely low, if so a revolution count is to be performed, during which an external power supply is turned off and remains. This means that only the energy of the Ummagnetisierungsimpulses for the entire revolution counting process 52 is available.

Another block 70 is used for signal generation, signal analysis and storage of relevant data, such as storing the number of complete 360 ° revolutions and a quadrant history, which will be discussed in more detail below. The block 70 has, for example, the xMR element 14 , the evaluation unit 15 , an (optional) comparator 72 (eg Schmitt trigger) and a memory element 74 on. The storage element 74 can a turn counter 76 and a (history) memory 78 exhibit. It is understood that the memory element 74 , the turn counter 76 and / or the history memory 78 also in the evaluation unit 15 can be integrated. The evaluation unit 15 can also be the rectifier 64 have integrated. The evaluation unit 15 can be realized for example in the form of a microcontroller or an ASIC chip. The impulse rotation sensor 12 is preferably designed as a Wiegand sensor. The xMR element 14 is preferably designed with high resistance to reduce energy consumption as much as possible.

In order to realize a simple, inexpensive and component-efficient solution, the concept described below can be selected.

The pulse wire sensor 12 is used exclusively as an energy generator and all information required for a revolution count and fine position determination are derived from a single component, here by the xMR element 14 is realized.

• – Sie verändern ihren Widerstand in Abhängigkeit des externen Magnetfelds.
• – Die xMR-Sensoren werden typischerweise durch einfache passive Widerstands-(Halb-)Brücken realisiert, die (nahezu sofort) nach dem Einschalten einer Versorgungsspannung, d. h. trägheitsfrei, ein auswertbares Signal liefern.
• – Sie lassen sich durch eine entsprechende Strukturierung hochohmig ausgestalten.

A solution that, as proposed in the prior art, a Hall sensor instead of the xMR element 14 is at the in the 3 shown arrangement or combination is not excluded in principle, but does not lead to the goal for the following reasons, ie not to an energy self-sufficient solution for the rotation count. A Hall sensor is a complex circuit compared to an xMR element, which typically has a relatively long transient phase after the external supply voltage is turned on. The transient phase is partly due to the fact that the Hall sensor requires a regulated operating voltage. During this transient phase, however, the energy passing through the impulse wire sensor can become 12 would be obtained, for example, by leakage currents or self-discharge of the capacitor 67 significantly reduce and thus further tighten requirements on the rest of the circuit in terms of a maximum allowable energy consumption. In general, a finely resolving single-turn sensor (ST sensor), in this case the Hall sensor, requires a high-quality signal with a high signal-to-noise ratio, so that a high resolution of typically ≥ 8 bit / 360 ° rotation can be generated , However, since only the energy of a remagnetizing pulse (40 to 150 nWs) is available, the multiturn rotary encoder (MT rotary encoder) uses 10 an ST sensor (xMR element 14 ), which manages with very little energy and yet delivers a good signal. Since the signal available at a Hall sensor evaluation signal, ie the Hall voltage, essentially determined by the product of the current and the magnetic induction, the Hall sensor for a given magnetic induction principle, not both requirements (high-quality signal and a lower Energy consumption). Therefore, the inventors of the present invention have recognized that a (high resistance) ST sensor (such as the xMR element 14 ) should be used. Of all known physical effects, which change an electrical property by means of magnetism in a solid state, the MR technology is particularly noteworthy. The MR effect delivers a signal with a very good signal-to-noise ratio even with weak magnetic fields. Although the various MR Technologies (such as AMR, GMR, TMR) on different effects, they share the following:

• - They change their resistance depending on the external magnetic field.
• - The xMR sensors are typically realized by simple passive resistance (half) bridges, which (almost immediately) after switching on a supply voltage, ie inertia-free, provide an evaluable signal.
• - They can be made high impedance by appropriate structuring.

The use of a high-impedance xMR element 14 as an ST sensor is therefore advantageous. When operating the MT rotary encoder 10 without external power supply, the energy needed to determine the number of 360 ° revolutions is the mechanical movement of the encoder shaft 18 or the rotation of the exciter magnet 16 won. The (preferably symmetrically operated) pulse-wire sensor 12 generated during the passage of the preferably bipolar exciter magnet 16 over 360 ° each have a positive and a negative Ummagnetisierungsimpuls 52 respectively. 52 ' as exemplified in 4A is shown.

in the 4A is a course 50 of the external magnetic field 40 according to the 1 and 3 shown. The history 50 of the magnetic field 40 reflected in a waveform 51 of the xMR element 14 contrary. In the 4A lie the two courses 50 and 51 one above the other. In the following it is assumed that the 360 ° revolution has its physical zero crossing at point P0. The strength of the external magnetic field 40 is at point P0 is maximum positive with positive orientation of the field 40 whereas the strength after a rotation of the encoder shaft 18 is almost zero by 90 ° and after a further rotation by 90 ° in the same direction is maximum negative.

Subsequently, it is assumed that the encoder shaft 18 so that turns the waveform 51 from left to right in the 4A runs. A "zero crossing" of the external magnetic field 40 So occurs when the encoder shaft 18 rotated by 90 °. A "zero crossing of the revolution count" is usually correct (evaluation logic) with one of the remagnetization pulses 52 whose relative (angular) position will be discussed in more detail below. The phase offset of the various "zero crossings" makes it necessary for the revolution count and the determination of a finely resolved position (that is, an absolute rotation angle within a 360 ° revolution) to perform a synchronization, which will also be discussed later.

So you go through the in the 4A shown sine wave (course 50 and 51 ) from left to right, so the polarity of the external magnetic field rotates 40 at the 90 ° position of the encoder shaft ( 18 ) and the field strength then reaches a trigger threshold T-, at which a first large Ummagnetisierungsimpuls 52-1 (see variant 1 in 2A and 2 B ) is produced. After another 180 ° turn, a second reverse polarity reversal pulse is generated 52-2 generated at a trigger threshold T +. The trigger threshold T + and the trigger threshold T- correspond to ignition thresholds 54-1 and 54-2 of the core 48 in the 4A are indicated by horizontal dashed lines. The number of two remagnetization pulses 52 per 360 ° revolution is due to the fact that the excitation magnet 16 bipolar. If a Quattropol were used, one would get 4 impulses 52 obtained per 360 ° rotation. The magnetic reversal pulses 52-1 and 52-2 lie with a signal course 50 respectively. 51 from left to right in so-called quadrants Q2 and Q4. In the 4A For example, a complete 360 ° revolution is logically subdivided into four equal quadrants Q1-Q4 such that each quadrant Q1-Q4 covers an angular range of 90 °. It is understood that the following explanations based on a 90 ° quadrant are merely exemplary in nature. In the same way, it would be conceivable to convert the "quadrants" into 45 ° or 120 ° segments, but this would make the evaluation more complex.

In the design of the MT rotary encoder 10 Care should be taken that the Ummagnetisierungsimpulse 52 are arranged substantially centrally (45 +/- 10 degrees) in the quadrants Q1-Q4. Leaving the shaft encoder 18 rotate in the opposite direction, so that the sine wave of the 4A is traversed from right to left, resulting in the Ummagnetisierungsimpulse 52'-1 and 52'-2 in the 4A shown by a solid line. The magnetic reversal pulses 52 ' lie in the quadrants Q1 and Q3, whereas the Ummagnetisierungsimpulse 52 lie in the quadrants Q2 and Q4. In the 4A is also clearly seen that the Ummagnetisierungsimpulse 52 may be offset by a few degrees relative to the respective quadrant center of 45 °. The relative position of the Ummagnetisierungsimpulse 52 respectively. 52 ' is essentially due to a spatial (angular) orientation of the pulse-wire sensor 12 opposite to the xMR element 14 conditionally. Other factors that influence the relative position of the Ummagnetisierungsimpulse 52 and 52 ' are, for example, in the field strength of the exciter magnet 16 , a sensitivity of the pulse-wire sensor 12 , the size of the distance between the exciter magnet 16 and the pulse wire sensor 12 , a choice of the hard magnetic and soft magnetic materials of the shell 46 and the core 48 and the like to see.

Since the Ummagnetisierungsimpulse 52 and 52 ' essentially centrally located in the associated quadrant Q1-Q4, receives the MT rotary encoder 10 a maximum tolerance range of ± 45 ° between an angular position of the pulse wire sensor 12 and the xMR element 14 (see also 1 ) and thus facilitates assembly on the manufacturer side assembly) of the corresponding components and is stable over wide temperature ranges.

If the evaluation described below is based on quadrants, it is advantageous if the Ummagnetisierungsimpulse 52 and 52 ' are each unique within one of quadrants Q1-Q4. Due to the switching hysteresis of the pulse wire sensor 12 are the impulses 52 and 52 ' with a clockwise or counterclockwise rotation of the encoder shaft 18 or of the exciter magnet 16 each in a neighboring quadrant. Together with a (stored) history of previously traversed quadrants, this allows a clear distinction between a clockwise rotation (Q2-Q4-Q2- ... etc.) and a counterclockwise rotation (Q1-Q3-Q1- ... etc.). In the example of 4A this means that the clockwise rotation, for example, by the Ummagnetisierungsimpulse 52 can be seen in the quadrants Q2 and Q4, whereas the left turn then by the Ummagnetisierungsimpulse 52 ' can be seen in the quadrants Q1 and Q3. From the polarity of the Ummagnetisierungsimpulse 52 and 52 ' In this embodiment, no conclusions can be drawn, since they are for the purpose of energy buffering via the rectifier 64 passed and optionally in the condenser 67 be cached. The capacitor 67 then supplies the other circuit blocks, such as the transmitter 15 , the xMR element 14 , the comparator 72 and the memory element 74 , with a resulting operating voltage Vdd.

In the 4B is again the sine curve (see solid line) 4A shown on the one hand the magnetic field course 50 and on the other hand the course 51 a sine output of the xMR element 14 equivalent. The in the 4B The dashed line corresponds to a curve of a cosine output signal of the xMR element 14 , The quadrants Q1-Q4 correspond to four 90 ° angle regions of the sinusoidal magnetic field 40 upon rotation of the encoder shaft 18 or of the exciter magnet 16 , With an appropriate orientation of the 360 ° -measuring xMR element 14 At the same time, the sinusoidal curve corresponds to the curve of the output voltage of one of the bridge circuits (in this case sinusoidal signal) of the xMR element 14 , The second bridge circuit then provides the associated cosine of the signal. Thus, the four quadrants Q1-Q4 can also be interpreted as the two MSB (Most Significant Bits) of an ST fine position (absolute rotation angle).

• – Aktualisierung ausschließlich der Quadrantenhistorie;
• – Inkrementierung des Umdrehungszählers (vorliegend um eine halbe Umdrehung) und Aktualisierung der Quadrantenhistorie; oder
• – Dekrementierung des Umdrehungszählers (vorliegend um eine halbe Umdrehung) und Aktualisierung der Quadrantenhistorie.

Immediately after one of the Ummagnetisierungsimpulse 52 respectively. 52 ' has taken place, is the evaluation unit 15 operational. With the energy gained from the momentum, the position (strength of the external magnetic field 40 ) of the xMR element 14 through the evaluation unit 15 then the direction of the magnetic field 40 is derivable. The same applies to the quadrant Q1-Q4, in the last one pulse 52 respectively. 52 ' was triggered. A history (temporal sequence) of the passed quadrants can be found in the history memory 78 (see. 3 ) be deposited. A value (number of previous 360 ° revolutions) of the revolution counter 76 is through the evaluation unit 15 queried. This means that the evaluation unit 15 an old status (history of the last stored quadrant and the value of the revolution counter 76 ) from the memory element 74 asks or reads out. From the information (last saved quadrant from history and current quadrant of the xMR element 14 ) together, one of the following actions can be clearly performed:

• - updating exclusively the quadrant history;
• - incrementing the revolution counter (in this case by half a turn) and updating the quadrant history; or
• - Decrementing the revolution counter (in this case by half a turn) and updating the quadrant history.

Thereafter, the status (quadrant history and revolution count value) is updated according to the new data, and the updated data is restored to the memory element 74 saved.

The comparator 72 in the function block 70 of the 3 is only optional provided in the event that a level of the xMR element 14 not big enough to connect it directly to the evaluation unit 15 further processing.

If in addition to the energy of a Ummagnetisierungsimpulses 52 respectively. 52 ' external energy is available, the MT rotary encoder 10 not only realize the revolution count function just described, but also determine a unique position by a finely resolved position (absolute rotation angle) of the ST sensor (xMR element 14 ) is determined. For this purpose, the evaluation unit 15 the sine and cosine signals (cf. 4B ) of the xMR element 14 be fed directly and processed there to an absolute angle of rotation (value between 0 ° and 360 °). This can be done, for example, according to the usual methods, such as an Arctan calculation or a Cordic algorithm.

In the formation and subsequent output of the unique position (sum of absolute rotation angle and number of complete revolutions), it should be noted that the zero crossings are not identical. Without the synchronization of the information, the linked total position output would not be continuous. However, the synchronization of the information can be realized on the basis of the determined when switching on the external operating voltage ST fine position and derived therefrom current quadrant and the last stored quadrant (history of the last stored quadrant and the revolution counter value). From a respective information formed therefrom, a specific correction value for determining the exact and continuous total position from the ST and MT raw data can be assigned.

When operating the MT rotary encoder 10 with external power supply, the number of complete 360 ° revolutions even without the revolution counter 76 based on a determination of continuous zero crossings of the ST sensor (xMR element 14 ) be determined. This also eliminates the synchronization, since the zero crossing for the ST and the revolution counter is the same in this case. For highly dynamic operation of the MT rotary encoder 10 This achieves a better real-time capability, since the computational effort for the synchronization is completely eliminated and occurs only once after switching on the external supply voltage.

Furthermore, it is also possible once the revolution counter via the pulse wire sensor 12 and at the same time over the zero crossing count of the ST sensor. This provides a redundant system with high reliability or with a self-monitoring option.

The ST data can optionally be further improved in terms of resolution and accuracy by adding, in addition to the 360 ° measuring TMR element z. B. an over 180 ° -measuring AMR sensor (not shown) is used. As a matter of principle, this has a higher resolution by a factor of 2 (ie one bit) and shows particularly good values in terms of the signal-to-noise ratio of the noisy hysteresis. For example, the mounting can be done on the xMR element 14 opposite PCB side 28 (see. 1 ) below the pulse wire sensor 12 respectively.

• – Es sind nur ein einziger Impulsdrahtsensor 12 und ein einziger Erregermagnet 16 zwingend erforderlich.
• – Ein zusätzlicher, spezifischer Hall-Schalter zur Bestimmung einer Polarität des externen Magnetfelds 40 und/oder der Polarität der Ummagnetisierungsimpulse ist nicht erforderlich, da die Magnetfeldpolarität beim vorliegenden Lösungsansatz keine Rolle spielt.
• – Der ST-Sensor (xMR-Element 14) liefert als eine einzige Einheit alle Informationen, die für eine Umdrehungszählung erforderlich sind, und zwar direkt beim Erfassen der ST-Position, wobei ein zusätzlicher Schaltkreisaufwand eliminiert wird und die Gesamtkosten gesenkt werden. Wie zuvor erwähnt, ist es zum Beispiel nicht erforderlich, die Polarität der Ummagnetisierungsimpulse 52 bzw. 52' sowie die Magnetfeldpolarität zu erfassen und abzuspeichern.
• – Der MT-Drehgeber 10 erlaubt durch seine Quadranten-bezogene Auswertung hohe Montagetoleranzen und ist über weite Temperaturbereiche stabil.
• – Der MT-Drehgeber 10 stellt eine Lösung dar, die nicht nur einen Umdrehungszähler abbildet, sondern ist eine Low-Cost-Lösung für ein komplettes Gebersystem bestehend aus einem ST, MT und einer einfachen kostengünstigen Synchronisationseinheit.
• – Der MT-Drehgeber 10 ist energieautark und bedarf keiner Stützbatterie für eine Datensicherung, während die externe Spannungsversorgung abgeschaltet ist.
• – Der MT-Drehgeber 10 hat keine verschleißbehafteten Bauteile, wie zum Beispiel Getriebe, und auch keine hochempfindlichen Komponenten, wie zum Beispiel Glasscheiben.
• – Teure Flussleitstücke werden für den Impulsdrahtsensor 12 nicht benötigt.
• – Zur Ermittlung der Quadranten Q1-Q4 können im einfachsten Fall die zwei MSB des ST-Datenworts herangezogen werden. Diese können auch vereinfacht durch eine Digitalisierung der Sinus- und Kosinussignale des xMR-Elements 14 gebildet werden. Alternativ kann über einen Low-Power-AD-Wandler die ST-Position genauer ermittelt werden. Hierdurch lassen sich dann die Quadranten Q1-Q4 per Software in Bezug auf die Lage zu den Ummagnetisierungsimpulsen 52 bzw. 52' während der Phase einer Inbetriebnahme lernen. Dadurch erhält man einen maximalen Toleranzbereich von ±45°, und zwar unabhängig von einer realen Montagetoleranz, oder man kann bei einem sehr kompakten Drehgeber eine vorgegebene, eventuell ungünstige Relativlage des xMR-Elements gegenüber dem Impulsdrahtsensor 12 per Software korrigieren, um so auch eine extreme Miniaturisierung zu ermöglichen.
• – Optional ist mit einem zusätzlichen xMR-Element ein sehr hoch auflösender und genauer MT-Drehgeber realisierbar.

Some advantages of the so far indicated MT rotary encoder 10 are:

• - There are only a single impulse wire sensor 12 and a single exciter magnet 16 absolutely necessary.
• - An additional, specific Hall switch for determining a polarity of the external magnetic field 40 and / or the polarity of the Ummagnetisierungsimpulse is not required because the magnetic field polarity plays no role in the present approach.
• - The ST sensor (xMR element 14 ) provides as a single unit all the information required for a revolution count, directly upon detection of the ST position, eliminating additional circuitry overhead and reducing overall costs. For example, as previously mentioned, it is not necessary to change the polarity of the remagnetization pulses 52 respectively. 52 ' and to detect and store the magnetic field polarity.
• - The MT rotary encoder 10 allows high mounting tolerances due to its quadrant-related evaluation and is stable over wide temperature ranges.
• - The MT rotary encoder 10 represents a solution that not only maps a revolution counter, but is a low-cost solution for a complete encoder system consisting of an ST, MT and a simple low-cost synchronization unit.
• - The MT rotary encoder 10 is energy self-sufficient and requires no backup battery for a data backup while the external power supply is switched off.
• - The MT rotary encoder 10 has no components subject to wear, such as gearboxes, and no high-sensitivity components, such as glass panes.
• - Expensive flux guides are used for the pulse wire sensor 12 not required.
• - In the simplest case, the two MSBs of the ST data word can be used to determine the quadrants Q1-Q4. These can also be simplified by digitizing the sine and cosine signals of the xMR element 14 be formed. Alternatively, the ST position can be determined more accurately via a low-power AD converter. As a result, the quadrants Q1-Q4 can then be software-controlled with respect to the position to the magnetic reversal pulses 52 respectively. 52 ' learn during the commissioning phase. This gives a maximum tolerance range of ± 45 °, regardless of a real assembly tolerance, or you can in a very compact encoder a predetermined, possibly unfavorable relative position of the xMR element relative to the pulse wire sensor 12 corrected by software, so as to enable extreme miniaturization.
• - Optionally, a very high-resolution and accurate MT rotary encoder can be realized with an additional xMR element.

When using a 180 ° AMR sensor instead of a 360 ° TMR sensor as an xMR element 14 can be optional instead a dipole also an additional four-pole or multi-pole magnet as a magnet 16 for the control of the pulse wire sensor 12 are provided, which is then usually arranged offset radially. In this way, the same system principle can be applied, but then not half revolutions, but for example corresponding quarter revolutions counts.

Of course, the solution concept proposed here can be transferred to linear measuring systems.

The evaluation logic is based on a low-power technology. The evaluation unit 15 can be realized discretely, as an FPGA, as a microcontroller or as an ASIC.

The storage element 74 is preferably a low-power data memory, such as an FRAM. Other technologies, such as MRAM, etc., are equally applicable.

Referring to the 5 and 6 a path will be shown below, such as a (total) position of the encoder shaft 18 unambiguous, safe and reliable determinable. 5 shows an example of a normal operation, without the sense of rotation 20 (see. 1 ) will be changed. This means that no Reversierbetrieb is carried out, in which there is a change in direction of the direction of rotation 20 the encoder shaft 18 comes. This normal operation is not critical and always provides clear information, the (absolute) value of the revolution counter 76 (see. 3 ) guarantee. Based on 6 then, also exemplarily, a special case will be explained in which it can lead to a false count (the quadrant) and thus to a loss of the absolute position. This special case occurs when a change in direction occurs while the pulse wire 36 between states Z2 and Z3 of 2A located.

Referring to 5 is again the sinusoidal magnetic field course 50 of the 4A and 4B shown at the location of the pulse wire sensor 12 with a continuous rotation of the encoder shaft 18 or of the exciter magnet 16 without change of direction prevails. The amplitudes of the strength of the external magnetic field 40 are at "max. + "And" max. - ". Likewise, the ignition threshold 54 of the core 48 and an ignition threshold 56 of the coat 46 of the pulse wire 36 shown in the form of horizontal auxiliary lines, in which the magnetization or the field direction 44 (see. 2A ) of the core 48 or the coat 46 each in the direction of the applied external magnetic field 40 flips. For the purpose of easier understanding of the following explanations, a respective magnetization of the core 48 and the coat 46 at certain points Px.x of the magnetic field and signal course 50 respectively. 51 shown. Q1 to Q4 denote the 90 ° quadrants of a complete 360 ° revolution and also represent the above-mentioned two MSBs of the finely resolving ST sensor.

If in the 5 the bipolar exciter magnet 16 Starting at the zero crossing (P0) is continuously rotated without direction change in a fixed direction, so that the sine curve is always traversed from left to right, the pulse wire 36 subjected to the illustrated sinusoidal magnetic field strength and polarity. In this case, the points P0, P1.1, P1.2, P2.1, P2.2 are repeated in succession. The points P1.1, P1.2, P2.1 and P2.2 correspond to core magnetizations 48 (P1.1 and P2.1) or the mantle 46 (P1.2 and P2.2). In doing so take the core 48 and the coat 46 in these points the respective field directions shown 44 on (representation analogous to 2A ). Passing through the ignition thresholds 54 of the core 48 each becomes an energy-rich big impulse 52 (see variant 1 in 2 B ) from the pulse wire sensor 12 delivered (cf. 4A ), depending on the polarity of the external magnetic field 40 has a positive or negative sign. These Ummagnetisierungsimpulse 52-1 respectively. 52-2 are then used for counting the full 360 ° revolutions according to the method described above for the (voltage) supply, while an external power supply (not shown in the figures) of the MT rotary encoder 10 is switched off. The when reaching the ignition thresholds 56 of the coat 46 generated, relatively small and low - energy impulses (see variant 3 in 2 B ) can not be used as they do not have sufficient energy for signal evaluation.

Referring to 6 is one of several possible special cases in which, after a change of direction between P1.1 and P1.2, the count of the complete 360 ° revolutions is initially continued without an external power supply. The external power supply is turned on when the encoder shaft 18 less than about 180 ° after reversing the direction, so that the revolution counter 76 with the fine resolution ST sensor (xMR element 14 ) must be synchronized so that the total position can be correctly calculated from the number of 360 ° or 180 ° revolutions and a current ST position (absolute rotation angle) and shows no discontinuities. With a travel of more than 180 ° either the point P2.2 or P4.1 is run over, which then has a clearly evaluable and assignable magnetic reversal pulse 52 respectively 52 ' supplies.

• – Bei einer Rotation des externen Magnetfelds 40 von P0 nach P1.1 klappt der Kern 48 gegen die Mantelrichtung um und liefert, wie gewünscht, einen großen Ummagnetisierungsimpuls 52-1 (vgl. 4A).
• – Bei einer (sofort) darauf folgenden gegensinnigen Rotation des externen Magnetfelds 40 von P1.1 nach P3.1 klappt der Kern 48 erneut dort um, allerdings in die ursprüngliche, bisher unveränderte Mantellrichtung, und liefert dabei einen (unerwünscht niedrigen) Ummagnetisierungsimpuls (vgl. Variante 2 in 2B) mit einem mittleren Energiegehalt, der energetisch nicht ausreicht, um für eine kurze Zeitdauer ausreichend Energie bereitzustellen, die für eine Zählung der 360°-Umdrehungen erforderlich ist. Der Quadrant Q1 wird aufgrund der mittleren Impulshöhe nicht ”gesehen” bzw. nicht erfasst, wie es eigentlich erforderlich wäre, um die Quadrantenhistorie sicher und eindeutig fortzuführen.
• – Bei einer fortgesetzten Rotation (ohne weitere Richtungsänderung) vom Punkt 3.1 über den Punkt 3.2 (wo der vernachlässigbare kleine Impuls gemäß Variante 3 der 2B entsteht) bis in den Quadranten Q4 der 4, also in die undefinierte Zone 1, entsteht das nachfolgend beschriebene Problem, wenn man die Rotation in der undefinierten Zone Z1 im Punkt Px1 stoppt und die externe Spannungsversorgung zwecks Ermittlung einer eindeutigen (Gesamt-)Position der Geberwelle 18 einschaltet.
• – Die im Historienspeicher 78 aufgezeichnete Quadrantenhistorie der nacheinander durchlaufenden Quadranten Q1 bis Q4, die durch die beschriebene, kurzzeitige Positionsabfrage (Magnetfeldstärkenabfrage) des fein auflösenden ST-Sensors beim Erscheinen eines Ummagnetisierungsimpulses 52 bzw. 52' ermittelt wird, dient einerseits dazu, bei fehlender externer Spannungsversorgung den Umdrehungszähler 76 fortlaufend zu aktualisieren und zum Anderen, um beim Hinzuschalten der externen Spannungsversorgung den Umdrehungszähler 76 und den ST-Sensor (xMR-Element 14) zu synchronisieren. Zu diesem Zweck sind lückenlos mindestens zwei große Impulse (gemäß Variante 1 der 2B) je 360°-Umdrehung in einer (gleichbleibenden) Richtung erforderlich, um eine Eindeutigkeit des Zählvorgangs zu gewährleisten. Der Impuls in Q1 fehlt aber.

When passing through points P0, P1.1, direction reversal, P3.1, P3.2 with one following stop in the quadrant Q4 or in an "undefined zone 1 '" (Px1), whereby the external power supply is switched on in the holding position, the following procedure results:

• - With a rotation of the external magnetic field 40 from P0 to P1.1 the core works 48 against the jacket direction and provides, as desired, a large Ummagnetisierungsimpuls 52-1 (see. 4A ).
• - At a (immediately) subsequent reverse rotation of the external magnetic field 40 from P1.1 to P3.1 the core works 48 There again, but in the original, previously unchanged Mantellrichtung, and thereby delivers an (undesirably low) Ummagnetisierungsimpuls (see Variant 2 in 2 B ) having an average energy content that is insufficient in energy to provide sufficient energy for a short period of time required to count the 360 ° revolutions. The quadrant Q1 is not "seen" or captured due to the average pulse height, as would actually be required to safely and unambiguously continue the quadrant history.
• - For a continued rotation (without further change of direction) from the point 3.1 about the point 3.2 (where the negligible small impulse according to variant 3 of the 2 B arises) to the quadrant Q4 of the 4 , that is, in the undefined zone 1, the problem described below arises when stopping the rotation in the undefined zone Z1 at the point Px1 and the external power supply to determine a unique (total) position of the encoder shaft 18 turns.
• - The in the history store 78 recorded quadrant history of successively passing quadrants Q1 to Q4, by the described short-term position query (magnetic field strength query) of the finely resolving ST sensor at the appearance of a Ummagnetisierungsimpulses 52 respectively. 52 ' is determined on the one hand serves, in the absence of external power supply, the revolution counter 76 to update continuously and on the other to turn the external power supply to the revolution counter 76 and the ST sensor (xMR element 14 ) to synchronize. For this purpose, at least two large pulses (according to variant 1 of 2 B ) each 360 ° revolution in a (constant) direction required to ensure uniqueness of the counting process. The impulse in Q1 is missing.

In the situation just described, the case arises that after switching on the external power supply, the ST position is clearly readable (compare Px1 or Px2 in the respective quadrant Q4). The recorded history, in particular the last stored history value Q2, however, does not allow a clear statement as to whether the encoder shaft 18 , and thus the excitation magnet 16 , last rotated about 180 ° counterclockwise or clockwise. In both cases, the ST sensor delivers the same external magnetic field strength at Px1 or Px2. The reason for this inaccuracy is that the medium-sized reversal pulse triggered at P3.1 does not permit quadrant detection by the ST sensor because there is too little energy.

Thus, a - although only temporary - false position determination in a size of ± 180 ° after switching on the external supply voltage is possible, so that the synchronization with the single turn is not given error-free. However, the position determination is only temporarily wrong, because when driving over the points P2.1 or P4.1 again large Ummagnetisierungsimpuls the variant 1 (see. 2 B ) that would trigger an update of the now lost unique information. This means that for a pure counting of entire 360 ° revolutions with an accuracy of ± 180 °, no corrective measures must be taken even after switching on the supply voltage, if the encoder shaft 18 not in the undefined zones.

If the point P2.1 is crossed over, a large pulse is generated in the quadrant Q4, from which it can be concluded that the sine curve continues to run from left to right. Will be the point 4.1 Run over, a large impulse is generated in quadrant Q3. Pulses in quadrants Q1 and Q3 mean that the sine curve is traversed from right to left, that is, a change of direction has taken place when the last stored quadrant value was Q2.

The undefined zones Z1 and Z2 are by the ignition thresholds 54 of the core 48 conditionally. The undefined zone 1 extends at least from the point P4.1 to the point P ', the point P corresponding to the point P2.1 in the subsequent cycle. The same applies to the undefined zone Z2 whose minimum extent extends from the point P2.1 to the point P2 ', the point P "corresponding to the point P4.1 of a preceding cycle. If you want to consider additional hystereses safely, the z. B. are caused by temperature fluctuations of the ST sensor, the right boundary of the undefined zone Z1 can be extended to the end of the previous quadrant Q4 and the left boundary of the undefined zone Z2 on the left edge of the quadrant Q3, so that the undefined zones Z1 'and Z2' receives.

There are now different possibilities, despite the in the 6 illustrated problem, the position of the MT rotary encoder 10 to be clearly determined.

In a first approach, the coil becomes 38 of the pulse wire sensor 12 energized for a short time to respond to an additional (test) pulse as an additional signal by the pulse-wire sensor ( 12 ) to create.

A distinguishing feature that leads to a uniqueness with respect to the undefined zones Z1 and Z2, respectively, is the fact that the respective magnetization directions of the core 48 and the coat 46 are different in the two zones Z1 and Z2 (see field directions 44 in 6 at Px1 = P3.2 or Px2 = P1.2).

In order to extract this information, the inventors propose the following procedure. Immediately after switching on the external supply voltage is in the already existing coil 38 a short electrical (test) pulse with a predetermined, quadrant-dependent sign and given energy briefly coupled. For this purpose, z. B. in the evaluation 15 a corresponding circuit block may be provided which is in 3 not shown to be expectorant. At a sufficient current strength of the test pulse is in the coil 38 - next to the external magnetic field 40 - generates an additional magnetic field, which is the magnetization of the wire 36 either counteracts or strengthens them. In an opposite direction of magnetic coil 38 and with a suitable dimensioning of the additional field, the magnetization of the core works 48 abruptly and generates a short magnetic field change, which in turn produces a measurable electrical pulse in the coil 38 generated (reaction pulse, from which the additional signal is determined). If the duration of the externally injected electrical test pulse is not dimensioned too long, the reaction pulse of the wire can be dimensioned 36 be measured when folding. Depending on whether a reaction pulse is generated or not (additional signal), it can be unambiguously concluded whether the encoder shaft 18 is located in the undefined zone Z1 or in the undefined zone Z2. In this way the uniqueness of the revolution counter can be determined 76 restore. Thus, the synchronization with the ST sensor or the xMR element is also 14 possible.

7A shows a flowchart which on the waveform of the 6 as well as the first solution (test pulse via coil 38 ). In this case it is assumed that the encoder shaft 18 Coming from the left goes through the point P0 to the point P1.1, where the change of direction takes place, before the point P1.2 is reached. Subsequently, the encoder shaft 18 Turned so far that you get on the curve to the left to the point Px1, where the position of the encoder shaft 18 is queried. It should be noted that the encoder shaft 18 for the purpose of the query does not necessarily have to be stopped. If a query at point Px1 or Px2 (compare 6 ) takes place, the MT rotary encoder 10 switched on, ie supplied with external energy. This condition is reflected in the flow chart of 7A in step S10 again. Once the MT encoder 10 is supplied with an external energy, the evaluation unit 15 based on the quadrant history determine that the encoder shaft 18 located in the undefined zone Z1 or Z2. The last stored quadrant value is Q2 and was obtained at point P1.1.

Since the last stored quadrant of the history of the quadrant Q2 is, this immediately results in the undefined zone Z1 or Z2, which, in contrast to the zones Z1 'and Z2' are the same size and congruent. The undefined zones Z1 and Z2 can vary for different "last stored quadrants". Each quadrant can be assigned its own undefined zone. These zones are therefore preferably in advance in a read-only memory, such. B. in the memory elements 74 or in the evaluation unit 15 , deposited.

In step S14 it is queried whether the external field strength or the point Px1 or Px2 lies in the forbidden zone (Z1 or Z2) for the quadrant Q2. If it is outside the forbidden zone, the assignment between the measured value and the associated quadrant is possible without problems, so that the unique position (sum of absolute rotation angle and number of complete 360 ° revolutions) is determined with additional consideration of the quadrant history can (step S16). However, if the query in step S14 indicates that the measured value lies in the undefined zone, the above-mentioned test pulse is applied to the coil in step S18 38 given.

In a next step S20, a query is made in this case as to whether a magnetic reversal pulse has been triggered as a reaction pulse on the basis of the test pulse. If no reaction pulse has been triggered, the unique position may be determined in step S22 in the conventional manner (see step S16). Otherwise, the value of the revolution counter becomes 76 incremented or decremented. The incrementing and decrementing of step S24 depends on the current direction of rotation 20 the encoder shaft 18 from. In step S24, the revolution counter becomes 76 generally adjusted.

In step S26, after the general adjustment of the revolution counter, the unique Position of the encoder shaft 18 be determined in analogy to the steps S16 and S22.

It is understood that the polarity of the additional magnetic field to be generated as a function of the last stored quadrant value of the quadrant history can also be stored in advance in a suitable memory. Furthermore, it is understood that the reaction pulse is used as an additional signal for conventional evaluation.

The flowchart of 7B shows a generalization of the previously described method for determining a unique position of the encoder shaft, which is about the axis of rotation 19 rotates.

In a step S30, a history of quadrant values is stored in the history memory, each quadrant value being one of the remagnetization pulses 52 in the impulse wire sensor 12 is triggered by a specific change of the external magnetic field due to a rotation of the encoder shaft corresponds, each quadrant value of the evaluation unit 15 taking into account the current signal value (Px2) from the xMR element 14 due to the magnetic reversal pulse 52 to the evaluation unit 15 is delivered, is determined and to the history memory 78 is delivered.

During a period of time including a discrete time for which the unique position of the encoder shaft is to be determined, the following steps are performed. In a step S32, the evaluation unit 15 and the xMR element 14 supplied with external energy. In a step S34, a strength of the external magnetic field becomes 40 at the discrete time by means of the xMR element 14 and a corresponding signal value Px1 or Px2 to the evaluation unit 15 delivered. In a step 36, by means of the evaluation unit 15 determines in which of the quadrants Q1-Q4 the supplied signal value Px1 or Px2. In a step S38, the last quadrant value stored in a history memory is retrieved 78 was last stored in the history, the query by the evaluation 15 he follows.

In a step S40 is by the evaluation 15 checks whether the supplied signal value Px1 or Px2 is within the forbidden quadrant zone Z1 or Z2, which is assigned to the last stored quadrant value Q2, wherein for each quadrant value a specifically forbidden quadrant zone is determined in advance and stored.

If the supplied signal value Px1 or Px2 is outside the forbidden quadrant zone Z1 or Z2, in a step 42 the unique position is determined by summing the absolute rotation angle with a current revolution counter value. Otherwise, an additional signal is evaluated in a step S44, which is additionally evaluated by the pulse-wire sensor 12 is generated, this signal is a correction of the revolution counter value by means of the evaluation unit 15 and wherein the absolute rotation angle is determined based on the additional signal before the unique position is determined from the absolute rotation angle and the corrected rotation angle.

A second approach is in the 8th and 9 shown at least two wires 36 in the pulse wire sensor 12 be used.

In the 8A is a side view of a simplified illustrated MT rotary encoder 10 shown whose pulse wire sensor 12 ' two impulse wires 36-1 and 36-2 as well as a coil 38 which has the pulse wires 36-1 and 36-2 surrounds. In the view of 8B is a cross section of the pulse wire sensor 12 ' of the 8A shown. It can be seen that the two impulse wires 36-1 and 36-2 are arranged one above the other. The impulse wires 36-1 and 36-2 extend substantially parallel to each other. A longitudinal direction of the wires 36-1 and 36-2 is perpendicular to the axis of rotation 18 oriented.

As previously related to 6 described, is a causal problem in the signal evaluation is that the Ummagnetisierungsimpuls 52 respectively. 52 ' in quadrant Q1 is lost during reversing, because at this point only an average pulse is generated, the energetic for the required evaluation of the corresponding quadrant Q1 via the ST sensor or the xMR element 14 not enough.

To counteract this, the pulse-wire sensor can 12 ' of the 8th be used. A special feature, this impulse wire sensor 12 ' is that while he only has a single coil 38 but at least two wires 36-1 and 36-2 having. Both wires 36-1 and 36-2 give the above-described Ummagnetisierungsimpulse 52 or 52 'from when the MT rotary encoder 10 according to the arrangement of 1 with the pulse wire sensor 12 ' of the 8th is used. Because both wires 36-1 and 36-2 in each case the above-described Ummagnetisierungsimpulse 52 respectively. 52 ' give off, you get typically two Ummagnetisierungsimpulse 52 respectively. 52 ' per quadrant.

A bobbin 80 , the two wires 36 surrounds and the inside of the coil 38 is arranged, is made of a magnetically non-conductive material, such as. B. stainless steel, glass or plastic.

Due to the different relative spatial position of the wires 36-1 and 36-2 (see Distances a and b in 8A ) to the exciter magnet 16 are the ignition thresholds 54 and 56 for folding over the respective cores 48 and coats 46 shifted to each other. With a corresponding dimensioning, this leads to the fact that in 6 shown points P1.1 and P1.2 of the first wire 36-1 and the points P1.1 'and P1.2' of the second wire 36-2 are shifted in phase to each other so that the point 1.2 'is located in front of the point P1.1. Therefore, the above-described special case (ie medium energy pulse) when reversing for both wires 36-1 and 36-2 not possible at the same time and the unwanted error pattern can only a maximum of one of the wires 36-1 and 36-2 occurrence. Thus, even when reversing at least one large Ummagnetisierungsimpuls in one of the two wires 36-1 and 36-2 generated so that the quadrants can be clearly detected. Alternatively, the quadrant history is unique and can be used after switching on the external supply voltage together with the current ST position to restore the uniqueness and continuity of the actual (total) position to be detected.

Another alternative to the second approach 8th is in the 9A and 9B shown. The 9A shows a plan view of a pulse wire sensor 12 '' with at least two wires 36 where the coil 36 not shown. The 9B shows a cross section of wires 36-1 and 36-2 which are arranged side by side here. In the 8th were the wires 36-1 and 36-2 arranged one above the other. The wires 36-1 and 36-2 of the 9 lie in a plane parallel to the plane of rotation 32 (see 1 ) is arranged. The wires 36-1 and 36-2 of the 9 are not parallel within their arrangement plane, but enclose an angle with each other. If more than two wires 36 are used, so are all the wires 36 not oriented parallel to each other, but each have an angle to their neighbors. In the 9A are the two wires 36-1 and 36-2 exemplary arranged V-shaped.

Due to the different relative angular position of the wires 36-1 and 36-2 are the ignition thresholds 54 and 56 for folding the coats 46 and the cores 48 again slightly shifted to each other. It turns out the same effect as the pulse wire sensor 12 ' of the 8th one.

A third approach is in 10 shown. The MT rotary encoder 10 of the 10A is basically according to the arrangement of 1 constructed, in addition to the centrally arranged exciter magnet 16 further additional magnets 82 are shown. 10A shows a top view of the MT encoder 10 with several additional magnets 82 , 10B shows the magnetic field profile during a rotation of the encoder shaft 18 without change of direction. 10C shows the magnetic field course in a rotation with a change in direction.

Referring to 10A below is the structure of the MT rotary encoder 10 described, provided changes to the structure according to the 1 are affected. The exciter magnet 16 and the xMR element 14 (ST sensor) are still arranged centrically. The pulse wire sensor 12 is radially offset, that is arranged eccentrically. In addition to the central excitation magnet (dipole) 16 come several additional magnets 82 , here a total of four additional magnets 82-1 to 82-4 , for use. The additional magnets 82 are also radially offset to the axis of rotation 19 along a circumferential direction of the encoder shaft 18 arranged. The additional magnets 82 are preferably equally spaced with respect to their angular position. The additional magnetic fields of the additional magnets 82 are essentially parallel to the axis of rotation 19 aligned, whereas the external magnetic field 40 of the exciter magnet 16 still perpendicular to the axis of rotation 19 is oriented. The additional magnets 82 are arranged with alternating polarity (see N or S) to their respective neighbors. It is understood that the pulse wire sensor 12 is oriented accordingly to the additional magnetic fields of the additional magnets 82 to be able to capture. In this case, this means that the wire (s) 36 parallel to the axis of rotation 19 is oriented or are.

As described above, a causative problem is that one of the large remagnetization pulses 52 respectively. 52 ' in the 6 is lost during reversing, because under the special conditions described above, only an average pulse is generated instead of the large pulse. The average pulse energetically enough for the required reading of the corresponding quadrant on the xMR element 14 usually not out.

To counteract this, come the eccentrically arranged additional magnets 82 for use. The additional magnets 82 are used solely to control (power generation) of the pulse-wire sensor 12 , The centric dipole remains for the ST measurement. The additional additional magnets 82 are realized (radially or axially) discreetly and in a receiving flange not shown in detail, the encoder shaft 18 integrated. The additional magnets 82 but can z. B. be designed as a multipole ring.

The in the 10A shown arrangement of the additional magnets 82 guaranteed at a 360 ° rotation of the encoder shaft 18 in each quadrant Q1-Q4 a magnetic reversal pulse 52 respectively. 52 ' in points P1.1, P2.1, etc. (cf. 10B ). In case of a revision of the direction of rotation, however, the detection of the corresponding quadrant can be omitted (cf. 10C ).

This malfunction can be detected by means of software at every (large) magnetic reversal pulse 52 by taking into account the quadrant history (eg the last two quadrants or optionally the last quadrant and the last determined direction of rotation). For this purpose, the corresponding information with each major Ummagnetisierungsimpuls 52 respectively. 52 ' be cached. Due to the fact that when the external supply voltage is switched on, the current quadrant can be uniquely determined via the ST sensor and due to the fact that the quadrant history is stored, it is also possible to synchronize the ST position with the revolution counter.

In the 11 is shown a fourth approach, which is in the construction of the 10 but with an eight- or multi-pole additional magnet 82 ' is used. 11A shows a plan view. 11B shows a rotation without change of direction. 11C shows a turn with direction change in the quadrant Q1.

As in the third approach, the fourth approach is based on a multipolar auxiliary magnet 82 ' for the revolution counting. In the 11A are in the circumferential direction eight (or even higher pole) additional magnets 82'-1 to 82'-8 intended. This arrangement of additional magnets 82 ' ensures at least one, typically two major Ummagnetisierungsimpuls at a 360 ° rotation 52 respectively. 52 ' in each quadrant Q1-Q4 (compare 11B ). In case of a revision of the direction of rotation, it is also possible to occasionally produce a mean magnetic reversal pulse instead of a large magnetic reversal pulse. However, as per Q1-Q4 quadrant typically two large Ummagnetisierungsimpulse 52 respectively. 52 ' are generated, it is ensured that with the at least one large Ummagnetisierungsimpuls 52 respectively. 52 ' the respective quadrant Q1 to Q4 can be detected. The additional magnets 82 ' So deliver the above-mentioned additional signal.

Thus, in the fourth approach, both for a pure revolution count without external supply voltage and for synchronization with the ST when switching on the external supply voltage, any hardware or software corrective action is unnecessary. Consider the offset of the zero crossings between the ST and the revolution counter. The eight additional magnets 82'-1 to 82'-8 can be arranged in 45 ° angle segments, as in 11A is shown by way of example. The additional magnets 82 ' but can also be arranged in a different angle arrangement, if this for the control of the pulse-wire sensor 12 is more advantageous.

To sum up, it can be said that the four solutions outlined here are based on a quadrant system. This system can also be transferred to other reference systems, eg. B. on 120 ° segmented systems. From this, it is also possible to derive the revolution counting and the direction of rotation detection when detecting the "segment history" of the 120 ° segments. In the case of the fourth approach with eight additional magnets 82 ' then only six magnets are needed for the same solution principle. However, such a non-binary frame of reference usually entails major disadvantages in the subsequent correction algorithms for revolution counting or in synchronization with the ST. Binary values can be processed faster and more energy efficient.

Of course, instead of encompassing complete revolutions, angular segments of one revolution are countable. In this case, the corresponding angle segment should be absolutely coded. This principle can then also be transferred to linear measuring systems. In this case, linear, absolutely coded sub-segments are counted and a total position is determined from the counted segment number and the current segment position.

All axially oriented additional magnets 82 respectively. 82 ' of the 10 and 11 in the third and fourth approach can of course be radially oriented.

Based on the multi-pole technology shown for counting the revolution according to the third or fourth approach, a hollow shaft encoder can be realized. In this case, the concentrically seated dipole magnet can be replaced by a ring-shaped or disc-shaped, absolutely coded measuring standard for the ST sensor (cf. 12 ). This measuring standard does not necessarily have to be magnetic, but can, for. B. capacitive coded and interact with a corresponding ST sensor, if this ST sensor can be operated with a corresponding low energy. These will be explained in more detail below with reference to the 13 ff be given.

In the third and fourth approach are the additional magnets 82 respectively. 82 ' for the pulse wire sensor 12 oriented radially and the absolutely coded material measure is oriented axially. In principle, these orientations can also be reversed. Alternatively, both orientations can be realized axially or radially.

In 12 is a plan view of another embodiment of the MT rotary encoder 10 in which the absolutely coded ST measuring standard, the the exciter magnet 16 of the 1 corresponds, is realized in the form of a magnet ring. In this case, the xMR element is 14 arranged eccentrically above the ring.

In the following section of the description, reference will be made to FIGS 13 to 18 the structure and operation of an optical MT rotary encoder 10 ' (see 13 ) are explained, which has a material measure, which - instead of magnetic now - is now optically encoded and with a corresponding ST sensor 14 ' respectively. 100 interacts.

In the 13 is the structure of the optically acting MT rotary encoder 10 ' which is almost identical to the structure of the MT rotary encoder 10 of the 1 is. The only difference is in the optical ST sensor 14 ' to see here in the form of an optical sensor 100 (eg in the form of a photodiode) is realized. The optical sensor 100 can again, similar to the xMR element 14 of the 1 , on the bottom 30 the circuit board 24 be arranged. The optical sensor 100 is opposite to a light source (eg LED). Between the optical sensor 100 and the light source 102 is a coding disc 104 provided, which will be explained in more detail below. The optical coding disc 104 extends in the plane of rotation 32 of the exciter magnet 16 which is realized here again in the form of a (permanent) dipole. The exciter magnet 16 is centric to the shaft encoder 18 arranged. The optical sensor 100 and the light source 102 are eccentric to the axis of rotation 19 arranged.

• – Der Draht 36 besitzt einen hartmagnetischen Mantel 46 und einen weichmagnetischen Kern 48 und stellt somit ein bistabiles magnetisches Element dar. Ein äußeres Magnetfeld 40 mit einer bestimmten Stärke und einer dem Impulsdraht 36 entgegengesetzten Magnetisierungsrichtung lässt die Magnetisierungsrichtung des Drahts 36 schlagartig umklappen, (Wigand-Effekt).
• – In einer um den Draht 36 gewickelten Spule 38 induziert eine magnetische Flussänderung, die durch eine Rotation der Geberwelle 18 bzw. des Erregermagnets 16 hervorgerufen wird, einen ca. 20 μs langen elektrischen Ummagnetisierungsimpuls.
• – Der Energiegehalt eines solchen Ummagnetisierungsimpulses liegt im Bereich 40 bis 150 nWs und hängt u. a. von der Impulsdrahtlänge, Kennzahlen der Spule 38, Lastwiderständen und dergleichen ab.
• – Eine Länge des Ummagnetisierungsimpulses und ein Energiegehalt desselben sind weitgehend von der Änderungsgeschwindigkeit des Erregermagneten 16 unabhängig.

For the following consideration of the MT rotary encoder 10 ' of the 13 and 14 the following properties are of interest:

• - The wire 36 has a hard magnetic sheath 46 and a soft magnetic core 48 and thus represents a bistable magnetic element. An external magnetic field 40 with a certain strength and a pulse wire 36 opposite magnetization direction leaves the magnetization direction of the wire 36 flip over, (wigand effect).
• - In a round the wire 36 wound coil 38 induces a magnetic flux change caused by a rotation of the encoder shaft 18 or of the exciter magnet 16 is caused, about 20 microseconds long electrical Ummagnetisierungsimpuls.
• - The energy content of such a Ummagnetisierungsimpulses is in the range 40 to 150 nWs and depends inter alia on the pulse wire length, key figures of the coil 38 , Load resistors and the like.
• - A length of the Ummagnetisierungsimpulses and an energy content thereof are largely of the rate of change of the exciter magnet 16 independently.

In 14 is a block diagram of the MT rotary encoder 10 ' of the 13 shown. The first block 62 of the 14 is identical to the block 62 of the 3 built up. The optical sensor 100 can a photodiode 106 and a block 108 have signal generation. The block 108 can also register 110 to store special values, which will be discussed in more detail below.

While the external power supply is switched off, even with the optical solution, at least the revolution count must be energy self-sufficient. The pulse wire sensor 12 converts the kinetic energy of the wave motion into electrical energy in a pulsed manner and places it in the components 62 . 100 . 15 and 74 to disposal. Again, there is very little energy (40-150 nWs) available for counting the revolution while the external power supply is turned off. This means that the complete revolution counting process has to live on the energy content of a magnetic reversal pulse, which, for. B. in the capacitor 67 can be cached. Also in the solution described here is the pulse wire sensor 12 used exclusively as a generator. All necessary information for the revolution count and the fine position detection are obtained from the signal of the optical ST sensor 14 ' derived. As already explained above, other auxiliary sensors, such. B. Hall switch, not needed for the revolution count and are unnecessary. This allows a cost-effective and component-reduced design. This also simplifies the dimensioning and design of the exciter magnet 16 with respect to the pulse wire sensor 12 , since only the energy balance-relevant aspects must be considered and no additional signal-related boundary conditions must be considered.

However, the revolution counting generally requires an ST sensor that requires very little energy. This is not obvious, especially with optical sensors, since light sources generally consume a great deal of energy. Even modern high-efficiency semiconductor diodes (eg LEDs) require a current in the order of 2 mA to 40 mA in a conventional ST rotary encoder. But this is more than the pulse wire sensor 12 can deliver. Furthermore, further energy is required for the other system components, in particular for signal evaluation and storage.

In the solution described below, individual function modules, such. B. a light source 102 , an optical signal conditioning in the block 108 and the memory element 74 only very briefly through the evaluation unit 15 actively switched, ie supplied with energy. Very short-term means that the energy for the functional module is much shorter in time than the magnetic reversal pulse. In principle, a period of activity of the function modules is not tied to a fixed time frame, but only to how long they take to process their respective task.

The following is the operation of the MT rotary encoder 10 ' based on a pulse wire sensor 12 as an energy supplier and on the basis of an optical sensor for both the rotation count as well as for the determination of the exact fine position within a 360 ° rotation with reference to the 13 to 18 be explained.

During a revolution count without external supply voltage, the energy for determining the number of 360 ° revolutions becomes the mechanical movement of the encoder shaft 18 won, at the the excitation magnet 16 is rotatably attached. In symmetrical operation of the pulse wire sensor 36 becomes the continuous turning of the bipolar exciter magnet 16 over 360 ° each a positive and a negative Ummagnetisierungsimpuls 52 respectively. 52 ' when exceeding the required ignition thresholds 54 (see 4A ) generated. Again, the MT rotary encoder 10 ' dimensioned so that the ignition thresholds 54 lie as centrally as possible in the quadrants Q1-Q4. This gives the MT encoder 10 ' a maximum tolerance range of ± 45 ° between the angular position of the pulse wire sensor 12 and the optical ST sensor 14 ' (see 13 ). This also includes the assembly of the components of the MT rotary encoder 10 ' easy. The MT rotary encoder 10 ' is stable over wide temperature ranges.

• – Es wird lediglich die Quadrantenhistorie aktualisiert.
• – Der Umdrehungszähler 76 wird um eine halbe Umdrehung inkrementiert und die Quadrantenhistorie wird aktualisiert.
• – Der Umdrehungszähler wird um eine halbe Umdrehung dekrementiert und die Quadrantenhistorie wird aktualisiert.

Immediately after an operational readiness of the evaluation unit 15 What happens after generating a remagnetizing pulse becomes the position of the optical ST sensor 14 respectively. 100 queried. The same applies to the quadrant Q1-Q4, in which the Ummagnetisierungsimpuls 52 respectively. 52 ' last triggered. From the storage element 74 (see 14 ), the old status (quadrant history of the last stored quadrant and the revolution counter reading) is read out. From this information can be in accordance with 7 clearly derive one of the following actions:

• - Only the quadrant history is updated.
• - The revolution counter 76 is incremented by half a revolution and the quadrant history is updated.
• - The revolution counter is decremented by half a revolution and the quadrant history is updated.

Thereafter, the status (quadrant history and revolution count) is updated according to the new data and the updated data becomes in the memory element 74 saved.

The quadrants Q1-Q4 correspond to four angular ranges of the sinusoidal external magnetic field 40 during the rotation of the encoder shaft 18 or of the exciter magnet 16 (see 4A ). With a corresponding orientation of the 360 ° measuring optical ST sensor 100 relative to the pulse wire sensor 12 The position of the two MSB of the ST position corresponds at the same time (at least approximately) to the position of the 90 ° quadrant of the sine curve of the external magnetic field 40 , Therefore, it is sufficient in operation without an external supply voltage to determine only the two MSB of the ST position. With a digitally coded coding disc 104 Both MSBs can be read out directly (compare 16 ).

In an analog coded encoder, z. B. as a sine signal or cosine signal per 360 ° revolution (see 4B ), these signals can be digitized via a respective Schmitt trigger S in order to generate the quadrant information. Alternatively, an existing AD converter that provides high-resolution ST position information at external supply voltage can be used as a simple 2-bit AD converter.

To make an energy balance positive and the optical ST-sensor 100 To enable it to perform its function with such a small amount of energy requires measures, 14 and 17 be illustrated. 17 shows waveforms for various functional components of 14 ,

Referring to 17 is, after a Ummagnetisierungsimpuls was triggered at time t1, from which the operating voltage Vdd results, at time t2 alone the evaluation unit (AL) 15 energized and thus activated. The evaluation unit 15 activates the other function blocks energy-saving, as described below with reference to an exemplary sequence.

At the time t2, so practically at the same time or immediately after the start of the evaluation 15 , are the photodiode (s) (FD) 106 and one or several Schmitt triggers S, which are required for reading the ST-MSB. Thereafter, at time t3, the light source 102 , z. As an LED turned on. Between times t3 and t4, the photodiode has 106 reaches a value (FD-Sig) at which the Schmitt trigger S has switched and outputs a digital signal S-Sig, the z. In the register 110 for the rest of the process can be temporarily held. Thus, at time t4, the function blocks 106 , S and in particular the energy-intensive light source 102 be switched off because their function is no longer needed.

After an evaluation of all the photodiode signals, ie after the time t4, the information is therefore present in which quadrant the magnetic reversal pulse 52 respectively. 52 ' was triggered. Thus, the individual register contents of the digitized photodiode signals can be dispensed with and also the registers can be switched off after the time t4.

At time t5, the (non-volatile) memory becomes 74 activated and read out the data stored there (revolution counter value and quadrant history). These data are, as explained above, linked to the currently determined quadrant, updated and stored in the memory 74 written. After that, the memory can 74 be switched off again at time t7.

Previously, the Quadrant Discovery function block may already be disabled at time t6.

Finally, the evaluation unit also ends t8 15 controls its function, before at time t9 the Ummagnetisierungsimpuls decays.

It should already be noted here that in the process described here, it is in some cases also possible for individual functions to also run in parallel instead of purely sequentially.

When operating the MT rotary encoder 10 ' with an external supply voltage not only the above-described revolution count is realized, but also a fine position of the ST sensor 100 evaluated continuously. In the formation and subsequent output of the (total) position, which consists of the number of 360 ° revolutions of the revolution counter 76 and the finely resolved position (absolute rotation angle) of the ST sensor 100 It should be noted that the zero crossings of the ST and the MT are not identical. Without a synchronization of both pieces of information the linked total position output is not continuous. However, the synchronization of the two pieces of information can be realized on the basis of the ST fine positions of the derived current quadrants derived therefrom when the external supply voltage is switched on and the last-determined rotation counter values. The information is thus determined on the basis of the quadrant history and the rotation count. A respective information packet formed therefrom can be assigned a specific correction value for determining the exact and continuous overall position from the ST and MT raw data.

When operating the MT rotary encoder 10 ' with an external supply voltage, the number of 360 ° rotation even without the revolution counter 76 based on the determination of the continuous zero crossings of the ST sensor 100 be determined. This also eliminates the synchronization, since the zero crossings for both systems (ST and MT or revolution count) are the same in this case. In a highly dynamic operation of the MT rotary encoder 10 ' This achieves a better real-time capability, since the computational effort for the synchronization is completely eliminated and only occurs once, after switching on the external supply voltage.

Another aspect of the invention can be described as follows:
Set 1. Energy-autonomous multi-turn encoders ( 10 ) for detecting a number of complete 360 ° revolutions of a sensor shaft ( 18 ), which are arranged around a rotation axis ( 19 ) and at which a field magnet ( 16 ) for generating an external magnetic field ( 40 ) is fixed in a rotationally fixed manner, and for determining an absolute angle of rotation, a finely resolved position within a 360 ° rotation of the encoder shaft ( 18 ), the multi-turn encoder ( 10 ) for self-sufficient detection of the number of complete 360 ° revolutions of the encoder shaft ( 18 ) having:
a, preferably single, pulse sensor ( 12 ) for generating energy from a magnetic reversal pulse ( 52 ), which in the pulse sensor ( 12 ) by a sufficiently large change of a strength of the external magnetic field ( 40 ), wherein the magnetic field strength change by a rotation ( 20 ) of the exciter magnet ( 16 ) is caused;
a, preferably single, magnetic field sensor ( 14 ) for detecting the strength of the external magnetic field ( 40 ) and for generating a corresponding signal ( 51 ), whose signal value of the strength of the external magnetic field ( 40 ) and to the evaluation unit ( 15 ), whereby the signal ( 51 ) Ideally has a sinusoidal course when the excitation magnet ( 16 ) continuously with the encoder shaft ( 18 ) about the axis of rotation ( 19 ), and wherein the sinusoidal course is evaluated logically divided into a plurality of, preferably equal-sized, quadrants (Q1-Q4);
a revolution counter ( 76 ) for storing the number of complete 360 ° revolutions of the encoder shaft ( 18 );
a history memory ( 78 ) in which a history of quadrant values (Q1-Q4) can be stored; and
an evaluation unit ( 15 ) used to determine the number of complete 360 ° revolutions of the encoder shaft ( 18 ) is operated exclusively with energy from the Ummagnetisierungsimpulsen ( 52 ) is won;
wherein the evaluation unit ( 15 ) is adjusted:
deriving from the supplied signal value (Px1, Px2) one of the quadrants (Q1-Q4) in which the supplied signal value (Px1, Px2) lies, and a corresponding quadrant value to the history memory ( 78 ) during one of the magnetic reversal pulses ( 52 ) occurs.
Set 2. Multi-turn encoders ( 10 ) according to sentence 1, wherein the pulse sensor is a Wiegand sensor.
3rd set of multi-turn encoders ( 10 ) according to one of the sentences 1 or 2, wherein the magnetic field sensor ( 14 ) is high impedance and is an xMR element, in particular a TMR, AMR or GMR element.
Theorem 4. Multiturn encoders ( 10 ) according to any one of sentences 1 to 3, further comprising a rectifier ( 64 ) having.
5th set of multi-turn encoders ( 10 ) according to one of the sentences 1 to 4, wherein the exciter magnet ( 16 ) is a permanent magnet, in particular a dipole, which is preferably centric to the encoder shaft ( 18 ) is attached.
Set 6. Multi-turn encoders ( 10 ) according to one of the sentences 1 to 5, wherein the pulse sensor ( 12 ) and the magnetic field sensor ( 14 ) coaxial to the encoder shaft ( 18 ) and to the exciter magnet ( 16 ) are arranged such that the pulse sensor ( 12 ) and the magnetic field sensor ( 14 ) the exciter magnet ( 16 ) axially spaced opposite, when the encoder shaft ( 18 ) with the multi-turn encoder ( 10 ) is assembled.
Theorem 7. Multiturn encoders ( 10 ) according to one of the sentences 1 to 6, where n remagnetization pulses ( 52 ) for each of the 360 ° revolutions of the encoder shaft ( 18 ) and wherein every nth magnetic reversal pulse ( 52 ) of a pulse cycle, an updating of a value of the revolution counter memory ( 76 ) caused.
Set 8. Multi-turn encoders ( 10 ) according to any one of sentences 1 to 7, wherein an orientation of the magnetic field sensor ( 14 ) is selected relative to the pulse wire so that the Ummagnetisierungsimpulse ( 52 ) each lie substantially centrally in the respective quadrants (Q1-Q4).
Set 9. Multi-turn encoders ( 10 ) according to any one of sentences 1 to 8, further comprising an energy store ( 66 ) connected to the pulse sensor ( 12 ) is electrically connected and is charged only with energy from the Ummagnetisierungsimpulsen ( 52 ) is won.
Theorem 10. Method for determining a unique position of a sensor shaft ( 18 ), which are arranged around a rotation axis ( 19 ), by means of an energy self-sufficient multiturn rotary encoder ( 10 ) used to detect a number of complete 360 ° revolutions of the rotating encoder shaft ( 18 ) and for detecting an absolute angle of rotation, a finely resolved position (P) within a 360 ° rotation of the encoder shaft ( 18 ) indicates at which a field magnet ( 16 ) for generating an external magnetic field ( 40 ), which is at least used for a determination of the finely resolved position, wherein the multi-turn encoder ( 10 ) a pulse sensor ( 12 ), an energy store ( 66 ), a magnetic field sensor ( 14 ), a revolution counter ( 76 ), a history memory ( 78 ) and an evaluation unit ( 15 ), wherein the magnetic field sensor ( 14 ) a signal ( 51 ) with an ideally sinusoidal course, when the excitation magnet ( 16 ) continuously with the encoder shaft ( 18 ) about the axis of rotation ( 19 ) and wherein the sinusoidal curve is subdivided into a plurality of, preferably equal, quadrants (Q1-Q4), the method comprising the following steps:
Storing a history of quadrant values (Q2, Q4) in the history memory, each quadrant value (Q2, Q4) representing a remagnetization pulse (Q2, Q4) 52 ), which in the pulse sensor ( 12 ) by a specific change of the external magnetic field ( 40 ) due to a rotation of the encoder shaft ( 18 ) and corresponds to each quadrant value of the evaluation unit ( 15 ) taking into account a signal value (Px1, Px2) transmitted by the magnetic field sensor ( 14 ) due to the Ummagnetisierungsimpulses ( 52 ) to the evaluation unit ( 15 ) is determined, and to the history memory ( 78 ), where n remagnetization pulses ( 52 ) for each of the 360 ° revolutions of the encoder shaft ( 18 ) and wherein every nth magnetic reversal pulse ( 52 ) an update of the revolution counter in the form of a rotation-dependent incrementing or decrementing a value of the revolution counter by the evaluation unit ( 15 ) caused; and
during a period of time comprising a discrete time for which the unique position (Px1, Px2) of the encoder shaft ( 18 ), performing the following steps:
Supplying the evaluation unit ( 15 ) and the magnetic field sensor ( 14 ) with an external energy;
Detecting a strength of the external magnetic field ( 40 ) at the discrete time by means of the magnetic field sensor ( 14 ) and supplying the corresponding signal value (Px1, Px2) to the evaluation unit ( 15 );
Determining by means of the evaluation unit ( 15 in which the quadrant (Q3, Q4) is the supplied signal value (Px1, Px2);
Querying the last quadrant value (Q2), which was stored in the history memory last in the history, by the evaluation unit ( 15 );
Check by the evaluation unit ( 15 ), whether the supplied signal value (Px1, Px2) is within a forbidden quadrant zone (Z1, Z2) corresponding to the the last stored quadrant value (Q2) is assigned, wherein for each quadrant value (Q2, Q4) a specific forbidden quadrant zone (Z1, Z2, Z3, Z4) is determined in advance and deposited;
when the supplied signal value (Px1, Px2) is outside the forbidden quadrant zone (Z1, Z2), determining the unique position by summing the absolute rotation angle corresponding to the supplied signal value (Px1, Px2) with a current revolution counter value; or
otherwise, if the delivered signal value (Px1, Px2) lies within the forbidden quadrant zone (Z1, Z2), evaluating an additional signal, which is additionally detected by the pulse sensor ( 12 ), correcting the revolution counter value by means of the evaluation unit ( 15 ) based on the additional signal and determining the absolute rotation angle based on the additional signal before the unique position is determined from the absolute rotation angle and the corrected revolution counter value.
Theorem 11. The method according to sentence 10, wherein the specific forbidden quadrant zones (Z1, Z2) are stored in a memory of the evaluation unit ( 15 ) or in a separate memory element ( 74 ) are deposited.
Theorem 12. Method according to one of the sentences 10 or 11, wherein the pulse sensor ( 12 ) one, preferably single, impulse wire ( 36 ) and one, preferably single coil ( 38 ) having the pulse wire ( 36 ), wherein the pulse wire ( 36 ) an outer jacket ( 46 ) and one within the mantle ( 46 ) arranged core ( 48 ) having.
Theorem 13. The method according to sentence 12, wherein the outer limits of the forbidden quadrant zones (Z1, Z2) are determined by magnetic reversal ignition thresholds ( 54 ) of the core ( 48 ) are defined.
The sentence 14. The method according to any one of sentences 10 to 13, wherein the pulse sensor ( 12 ) one, preferably single, impulse wire ( 36 ) and one, preferably single coil ( 38 ) having the pulse wire ( 36 ), and wherein the step of evaluating the additional signal and correcting the revolution counter value comprises:
Energizing the coil ( 38 ) for a short period of time, allowing the external magnetic field ( 40 ) of the exciter magnet ( 16 ) an additional magnetic field is superimposed and thereby a test magnetic reversal pulse in the pulse wire ( 36 ), which is subsequently connected to the coil ( 38 ) is measurable, wherein an existence or nonexistence of the test remagnetization pulse as the additional signal from the coil ( 38 ) to the evaluation unit ( 15 ) is delivered;
Check by the evaluation unit ( 15 ), whether the additional signal contains the test remagnetization pulse or not; and
Correcting the value of the revolution counter ( 76 ) when the additional signal contains the test remagnetization pulse; or maintaining the current revolution counter value if the additional signal does not include the test remagnetization pulse.
Theorem 15. The method of clause 14, wherein the step of correcting the value of the revolution counter ( 76 ) a direction-dependent incrementing or decrementing the value of the current revolution counter ( 76 ) having.
The method of any one of sentences 10 to 15, wherein the pulse sensor ( 12 ) a first pulse wire ( 36-1 ), at least one second pulse wire ( 36-2 ), a winding body ( 80 ), in which the impulse wires ( 36-1 . 36-2 ) are arranged, and a, preferably single, coil ( 38 ), which in turn the bobbin ( 80 ), each of the impulse wires ( 36-1 . 36-2 ) an outer jacket ( 46 ) and one within the mantle ( 46 ) arranged core ( 48 ) and wherein the pulse wires ( 36 ) in a respective predetermined position in the winding body ( 80 ) are fixed.
Theorem 17. The method according to any of sentences 10 to 16, wherein outer limits of the respective forbidden quadrant zone (Z1, Z2, Z1 ', Z2') are determined by magnetization reversal ignition thresholds ( 54 ) of the cores ( 48 ) are defined.
Theorem 18. Procedure according to sentence 16 , wherein the Ummagnetisierungspulse ( 52 . 52 ' ) of the second pulse wire ( 36-2 ) can be used as additional signal.
Theorem 19. Procedure according to sentence 16 , where the impulse wires ( 36-1 . 36-2 ) in the axial direction of the encoder shaft ( 18 ) are spaced apart from each other, and are preferably arranged axially parallel to each other.
Theorem 20. Procedure according to sentence 16 , where the impulse wires ( 36-1 . 36-2 ) are arranged in a single plane which is substantially perpendicular to the axis of rotation ( 19 ) of the encoder shaft ( 18 ), and wherein the first impulse wire ( 36-1 ) makes an angle with each of the second pulse wires ( 36-2 ).
Theorem 21. Procedure according to sentence 16 , wherein the pulse sensor ( 12 ) coaxial with the exciter magnet ( 16 ), wherein the pulse wires ( 36-1 . 36-2 ) are arranged in at least one plane, each substantially perpendicular to the axis of rotation ( 19 ) of the encoder shaft ( 18 ) and substantially parallel to the plane of rotation ( 34 ) of the exciter magnet ( 16 ) is oriented.
Theorem 22. Method according to one of the sentences 10 to 21, wherein the exciter magnet ( 16 ) is a single dipole magnet that is in one plane ( 34 ) is arranged substantially perpendicular to the axis of rotation ( 19 ) is oriented.
Theorem 23. Method according to any one of sentences 10 to 22, wherein the pulse sensor ( 12 ) eccentric to the axis of rotation ( 19 ) of the encoder shaft ( 18 ) is arranged, wherein in addition to the coaxially arranged exciter magnet ( 16 ) at least four additional magnets are provided which are distributed uniformly in the circumferential direction with alternately oriented magnetic fields on the encoder shaft ( 18 ) are attachable, so that in each quadrant (Q1-Q4) at least one Ummagnetisierungsimpuls ( 52 . 52 ' ), wherein such Ummagnetisierungsimpulse, from the usual Ummagnetisierungsimpulsen differ, provide the additional signal.
Set 24. The method of clause 23, wherein the number of additional magnets is defined by 2 ^n, where n is an integer that is greater than the second

• – Es wird zwingend nur ein einziger Impuls(-draht-)sensor 12 bzw. 12' und nur ein einziger Erregermagnet 16 benötigt.
• – Ein zusätzlicher spezifischer Hall-Schalter zur Erfassung der Polarität des externen Magnetfelds 40 ist nicht erforderlich, da die Magnetpolarität beim vorliegenden Prinzip der Erfindung keine Rolle spielt. Es werden nur die Quadranten-Informationen des ST-Sensors zur Ermittlung der Anzahl von vollständig durchlaufenden 360°-Umdrehung herangezogen.
• – Der ST-Sensor 14, 14' bzw. 100 liefert als einziges Bauteil alle erforderlichen Informationen für die Umdrehungszählung und für die Erfassung der ST-Feinposition pro 360°. Auf diese Weise wird der Schaltkreis vereinfacht. Somit senken sich auch die Gesamtkosten. Es ist z. B. nicht erforderlich, die Polarität eines Ummagnetisierungsimpulses sowie die Magnetfeldpolarität zu erfassen und abzuspeichern.
• – Es wird eine Quadranten-bezogene Auswertung durchgeführt, die eine hohe Montagetoleranz ermöglicht und über weitere Temperaturbereiche stabil ist.
• – Die Erfindung bildet nicht nur einen Umdrehungszähler ab, sondern stellt eine günstige Lösung für ein komplettes Gebersystem dar, welches insbesondere aus einem optischen ST-Sensor, einer (Umdrehungszähl-)Auswerteeinheit 15 und einer einfachen, kostengünstigen Synchronisationseinheit (z. B. in Form der Auswerteeinheit 15) steht.
• – Die MT-Drehgeber 10 und 10' sind energieautark. Es wird keine Stützbatterie für eine Datensicherung benötigt, während die externe Versorgungsspannung abgeschaltet ist.
• – Er werden keine verschleißbehafteten Bauteile wie z. B. Getriebe, eingesetzt.
• – Es werden keine teuren Flussleitstücke benötigt.
• – Zur Ermittlung der Quadranten können im einfachsten Fall die zwei MSB des ST-Datenworts herangezogen werden.

The advantages of the MT rotary encoders shown here 10 and 10 ' compared to the prior art are listed below, inter alia:

• - It is mandatory only a single pulse (wire) sensor 12 respectively. 12 ' and only a single exciter magnet 16 needed.
• - An additional specific Hall switch to detect the polarity of the external magnetic field 40 is not necessary because the magnetic polarity in the present principle of the invention does not matter. Only the quadrant information of the ST sensor is used to determine the number of complete 360 ° revolutions.
• - The ST sensor 14 . 14 ' respectively. 100 is the only component that provides all the necessary information for the revolution counting and for the acquisition of the ST fine position per 360 °. This simplifies the circuit. This also reduces the total costs. It is Z. B. is not necessary to detect the polarity of a Ummagnetisierungsimpulses and the magnetic field polarity and store.
• - A quadrant-related evaluation is carried out, which allows a high mounting tolerance and is stable over other temperature ranges.
• - The invention not only forms a revolution counter, but represents a favorable solution for a complete encoder system, which in particular from an optical ST-sensor, a (revolution counting) evaluation 15 and a simple, inexpensive synchronization unit (eg in the form of the evaluation unit 15 ) stands.
• - The MT rotary encoders 10 and 10 ' are energy self-sufficient. No back-up battery is needed for a backup while the external supply voltage is off.
• - He will no wear-related components such. As transmission used.
• - No expensive flux guides are needed.
• - In the simplest case, the two MSBs of the ST data word can be used to determine the quadrants.

In the optical solution, no magnetically highly sensitive ST sensor (xMR element 14 ), which would have to be carefully shielded against external (foreign) magnetic fields.

A high-resolution and high-precision MT rotary encoder with ST functionality can be implemented on the basis of the optical principle of operation.

Alternatively, other energy generators than the pulse wire sensor 12 respectively. 12 ' be used. Therefore, it is generally spoken of a pulse sensor. In general, the following principles are known for pulse sensors.

An inductive mechatronic system based on a slightly magnetized leaf spring, which is deflected when a corresponding magnet moves past it and suddenly swings back when the magnetic holding moment falls below the mechanical restoring force (cf. DE 102 29 978 B4 ). As a result, one or more pulses are induced in a coil surrounding the leaf spring.

A similar method uses a piezoelectric element, which sits on a leaf spring, for spontaneous energy conversion (see. DE 2004 055 625 A1 ).

Another method is based on a reed switch, which is wrapped with a coil. When passing a corresponding magnet, the reed switch switches and thereby changes the magnetic flux so abruptly that also a pulse is generated in the coil. However, a disadvantage of this system is the wear due to the mechanical support as well as a shock and vibration sensitivity caused by the intrinsic mass.

Instead of a dipole, a multi-pole magnet can also be provided for driving the pulse sensor. Thus, the same system principle can be applied, but then not half turns, but z. B. correspondingly smaller angle segments of a 360 ° revolution counts. This can be z. B. be interesting when using the principle of the invention in connection with a hollow shaft variant, if the magnet as a dipole bad or not at all can be realized, for. B. because the diameter is too large, and must be resorted to a multi-pole magnet.

In 18 is an optical encoder disk 104 ' shown with (multi-pole) additional magnets 82 can be used according to the embodiment described above for a hollow shaft variant. By way of example, the 4-pole variant is shown in combination with an optical code carrier. In this case, an absolutely coded optical measuring standard assumes the role of in the 10a . 11a or 12 shown absolute magnetic material measure.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19626654 A1 [0002]
• EP 0516572 B1 [0003]
• DE 10259223 B3 [0004, 0004, 0004, 0004, 0008]
• DE 3408478 C1 [0005, 0055]
• EP 0231474 B1 [0006, 0007]
• DE 4407474 C2 [0007, 0007]
• DE 10229978 B4 [0166]
• DE 2004055625 A1 [0167]

Claims (9)

Energy-autonomous multiturn rotary encoder ( 10 ' ) for detecting a number of complete 360 ° revolutions of a sensor shaft ( 18 ), which are arranged around a rotation axis ( 19 ) and at which a field magnet ( 16 ) for generating an external magnetic field ( 40 ) is fastened in a rotationally fixed manner and on which an optical coding disk ( 104 ) is fixed to determine an absolute angle of rotation, a finely resolved position within a 360 ° rotation of the encoder shaft ( 18 ), the multi-turn encoder ( 10 ) for self-sufficient detection of the number of complete 360 ° revolutions of the encoder shaft ( 18 ) has a, preferably single, pulse sensor ( 12 ) for generating energy from a magnetic reversal pulse ( 52 ), which in the pulse sensor ( 12 ) by a sufficiently large change of a strength of the external magnetic field ( 40 ), wherein the magnetic field strength change by a rotation ( 20 ) of the exciter magnet ( 16 ) is caused; a, preferably single, optical sensor ( 14 '; 100 ) for detecting a current position of the encoder shaft ( 18 ) and for generating a corresponding signal whose signal value of the current position of the encoder shaft ( 18 ) and to the evaluation unit ( 15 ), whereby the signal ( 51 ) has a, preferably sinusoidal, course when the exciter magnet ( 16 ) continuously with the encoder shaft ( 18 ) about the axis of rotation ( 19 ), and wherein the course is evaluated logically divided into a plurality of, preferably equal-sized, quadrants (Q1-Q4); a revolution counter ( 76 ) for storing the number of complete 360 ° revolutions of the encoder shaft ( 18 ); a history memory ( 78 ) in which a history of quadrant values (Q1-Q4) can be stored; and an evaluation unit ( 15 ) used to determine the number of complete 360 ° revolutions of the encoder shaft ( 18 ) is operated exclusively with energy from the Ummagnetisierungsimpulsen ( 52 ) is won; wherein the evaluation unit ( 15 ) is adapted to derive from the supplied signal value (Px1, Px2) one of the quadrants (Q1-Q4) in which the supplied signal value (Px1, Px2) is located, and a corresponding quadrant value to the history memory ( 78 ) during one of the magnetic reversal pulses ( 52 ) occurs. Multi-turn encoders ( 10 ' ) according to claim 1, wherein the optical sensor ( 100 ) has an LED and a Schmitt trigger. Multi-turn encoders ( 10 ' ) according to one of claims 1 or 2, wherein the pulse sensor is a pulse-wire sensor ( 12 ), the at least one pulse wire ( 36 ) and a coil ( 38 ) having the at least one wire ( 36 ) surrounds. Multi-turn encoders ( 10 ' ) according to one of claims 1 to 3, further comprising an absolutely coded coding disc ( 104 ; 104 ' ) at the shaft of the encoder ( 18 ) is rotatably fastened. Multi-turn encoders ( 10 ' ) after one of paragraphs 1 to 4, which also contains a register ( 110 ) for storing an output signal (S-Sig) of the optical sensor ( 14 '; 100 ) having. Method for determining a unique position of a sensor shaft ( 18 ), which are arranged around a rotation axis ( 19 ), by means of an energy self-sufficient multiturn rotary encoder ( 10 ), which is preferably designed according to one of claims 1 to 5 and which is used for the optical detection of a number of complete 360 ° revolutions of the rotating encoder shaft ( 18 ) and for the optical detection of an absolute angle of rotation is set, a finely resolved position (P) within a 360 ° revolution of the encoder shaft ( 18 ) indicates at which a field magnet ( 16 ) for generating an external magnetic field ( 41 ), which is used to generate an energy needed for revolution counting, wherein the multi-turn encoder ( 10 ' ) a pulse sensor ( 12 ), an optical sensor ( 14 '; 100 ), a revolution counter ( 76 ), a history memory ( 78 ) and an evaluation unit ( 15 ), wherein the optical sensor ( 14 '; 100 ) a signal ( 51 ) supplies with a, preferably sinusoidal, course, when the encoder shaft ( 18 ) continuously about the axis of rotation ( 19 ) and wherein the course is subdivided into a plurality of, preferably equal, quadrants (Q1-Q4), the method comprising the following steps: providing an evaluation energy at a time t1 when a magnetic reversal pulse ( 52 ) is generated in the pulse sensor; Activating the evaluation unit ( 15 ) and the optical sensor ( 100 ) at a time t2 immediately after the evaluation energy is ready; then detecting an optical value obtained by illuminating the encoder disc ( 104 ), and outputting a corresponding signal (S-Sig); Determining and outputting a current quadrant corresponding to the output signal (S-Sig) in which the magnetic reversal pulse ( 52 ) has taken place by the evaluation unit ( 15 ); Activate the memory element ( 74 ) and updating a quadrant history having recently stored quadrant values; and deactivating the evaluation unit ( 15 ) after all the aforementioned steps have been carried out and before the magnetic reversal pulse ( 52 ) decays. The method of claim 6, further comprising: Switch off the optical sensor ( 100 ) after the corresponding signal (S-Sig) is generated and output. Method according to claim 6 or 7, further comprising: switching on a light source ( 102 ), after the evaluation unit ( 15 ) and the optical sensor ( 100 ) are activated and turn off the light source ( 102 ) when the corresponding signal (S-Sig) has been detected. Method according to one of claims 6 to 8, wherein the optical sensor ( 100 ) a photodiode ( 106 ) and a Schmitt trigger (S).

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