Hysteresis correction for rotation sensor device and method for performing hysteresis correction

Abstract

Apparatus and method for performing hysteresis correction of a rotation sensor device that detects a bearing position and a direction of rotation of a rotatable shaft, the device providing a direction of rotation signal indicative of the direction of rotation of the shaft and a counter reading indicative of the bearing position, the method comprises the following steps: storing a current signal value when at least one signal change of the rotation sensor device occurs in a previous switching time period of the rotation sensor device; comparing a signal value of the first digital sensor signal, which is present during re-activation, with a stored signal value of the first digital sensor signal when re-activation of the rotation sensor device is detected; for the case of a difference between the two compared signal values, a correction value is determined on the basis of the difference between the two compared signal values and the stored rotational direction, and once a first new signal change occurs in the first digital sensor signal since a re-activation of the rotational sensor device, the correction value is determined on the basis of the stored rotational direction. And the correction value is added to the counter reading.

Description

Technical Field

[0001] The invention relates to a rotation sensor device for determining a bearing position and a rotation direction of a rotatable shaft. The invention also relates to a method for performing a hysteresis correction for a rotation sensor device which is designed to detect a bearing position and a rotation direction of a rotatable shaft. Background Art

[0002] Rotation sensor devices use event-based sensors, such as magnetic or optical sensors, to detect the bearing position of the shaft. Here, a sensor unit is used which processes the sensor signal and provides a digital sensor signal. In the case of such sensor units, switching is performed based on a signal threshold value. In the case of such sensor units, it is possible that errors caused by hysteresis occur when switching off and then switching back on. For example, it is possible that, despite the unchanged position of the shaft, the sensor unit still provides a first signal value before switching off and a second signal value different from the first signal value after switching on. A possible reason for this is that switching changes can occur in the hysteresis region due to the switching on of the internal measuring bridge.

[0003] It is therefore an object of the present invention to provide a hysteresis correction for a rotary sensor unit which allows errors occurring due to hysteresis to be detected and corrected. Summary of the invention

[0004] The invention relates to a rotation sensor device according to claim 1 and to a method for operating a rotation sensor device according to the further independent claims.

[0005] Further refinements are set forth in the dependent claims.

[0006] According to a first aspect, a rotation sensor device is provided for determining a bearing position and a rotation direction of a rotatable shaft, wherein the rotation sensor device has:

[0007] a first sensor unit for generating a first digital sensor signal, the first sensor unit comprising a first sensor arranged at the shaft; and a second sensor unit for generating a second digital sensor signal, the second sensor unit comprising a second sensor arranged at the shaft,

[0008] an evaluation device designed to generate a rotational direction signal indicating the rotational direction of the shaft based on the first digital sensor signal and the second digital sensor signal, wherein the evaluation device is designed to count signal pulses of the first digital sensor signal with a sign that is dependent on the rotational direction and to provide a counter reading,

[0009] The rotation sensor device includes a hysteresis correction device, which has:

[0010] a memory device, which is designed to store a current signal value of the first digital sensor signal and a current direction of rotation before the rotation sensor device is switched off;

[0011] a comparison device, which is designed to compare the signal value of the first digital sensor signal with the signal value of the first digital sensor signal stored by the storage device when a renewed switching on of the rotation sensor device is detected;

[0012] - A correction device, which is designed to determine a correction value based on the difference between the two compared signal values ​​and the rotation direction stored by the storage device in the event of a difference between the two signal values, wherein the correction device is constructed to add the correction value to the counter reading as soon as a first new signal change occurs in the first digital sensor signal after the rotation sensor device is switched on again.

[0013] The storage device is designed to store the current signal value of the first digital sensor signal and the current direction of rotation before the rotation sensor device is turned off. At the next reconnection, the signal value of the first digital sensor signal is compared with the stored signal value. If the two compared signal values ​​differ, this indicates that an error caused by hysteresis has occurred. In this way, it is possible to reliably identify errors caused by hysteresis. In order to correct this error caused by hysteresis, a correction value is determined based on the difference between the two signal values ​​and the direction of rotation before the shutdown. The correction value provides the following feasible solution, namely: the counter reading of the rotation sensor device is corrected in this way so that the pulses lost due to hysteresis can be taken into account. As soon as the first new signal change occurs since the reconnection, the correction value is added to the counter reading. In this way, a corrected counter reading is obtained, which corrects the error caused by hysteresis. The advantage is higher accuracy when detecting the rotation of the shaft. In particular, when the rotation sensor device is used in an instrument that is often connected and turned off, a robust and interference-free detection of the rotation of the shaft is ensured. The reliability of the rotation sensor is improved. The susceptibility to interference is reduced.

[0014] Furthermore, the invention relates to a method for carrying out a hysteresis correction for a rotation sensor device which is designed to detect a bearing position and a rotation direction of a rotatable shaft, wherein the rotation sensor device has:

[0015] a first sensor unit for generating a first digital sensor signal, the first sensor unit comprising a first sensor arranged at the shaft; and a second sensor unit for generating a second digital sensor signal, the second sensor unit comprising a second sensor arranged at the shaft,

[0016] an evaluation device designed to generate a rotational direction signal indicating the rotational direction of the shaft based on the first digital sensor signal and the second digital sensor signal, wherein the evaluation device is designed to count signal pulses of the first digital sensor signal with a sign that is dependent on the rotational direction and to provide a counter reading,

[0017] The method comprises the following steps:

[0018] - storing the current signal value of the first digital sensor signal and the current direction of rotation upon detection of a switch-off of the rotary sensor device, at least if at least one signal change of the first digital sensor signal occurred within a previous switch-on period of the rotary sensor device,

[0019] upon detecting that the rotary sensor device has been switched on again, comparing the signal value of the first digital sensor signal present at the time of the switch-on again with a stored signal value of the first digital sensor signal,

[0020] In the event that the two compared signal values ​​differ, a correction value is determined based on the difference between the two compared signal values ​​and the stored direction of rotation, and the correction value is added to the counter reading as soon as a first new signal change occurs in the first digital sensor signal after the rotation sensor device is switched on again.

[0021] According to a preferred specific embodiment, the first sensor is a first magnetic sensor, in particular a Hall sensor, and / or the second sensor is a second magnetic sensor, in particular a Hall sensor.

[0022] According to a preferred embodiment, the first sensor is a first optical sensor.

[0023] According to a further preferred embodiment, the first sensor is a first optical sensor and the second sensor is a second optical sensor.

[0024] According to a preferred specific embodiment, the first sensor is designed to generate a first analog sensor signal, wherein the first sensor unit comprises a first Schmitt trigger circuit which is designed to convert the first analog sensor signal into a first digital sensor signal.

[0025] According to a preferred specific embodiment, the second sensor is designed to generate a second analog sensor signal, wherein the second sensor unit comprises a second Schmitt trigger circuit which is designed to convert the second analog sensor signal into a second digital sensor signal.

[0026] The evaluation device preferably comprises a counter which is designed to count signal pulses of the first digital sensor signal with a sign that is dependent on the direction of rotation.

[0027] The evaluation device is preferably designed to count the first new signal changes of the first digital sensor signal with a sign that is dependent on the current direction of rotation, starting from when the rotational sensor device is switched back on.

[0028] Advantageously, the rotation sensor device comprises a state indicator, wherein the hysteresis correction device is designed to reset the state indicator when the rotation sensor device is switched on, to set the state indicator when a first new signal change of the first digital sensor signal occurs since said switching on, and to store current values ​​of the first digital sensor signal and of the rotation direction signal for the case in which the state indicator is set when the rotation sensor device is switched off.

[0029] Preferably, the second sensor is arranged offset by a predefined angle relative to the first sensor, as viewed in the direction of the axis.

[0030] It is further preferred that the hysteresis correction device is designed as part of the evaluation device.

[0031] According to a preferred embodiment, the storage device includes a non-volatile memory.

[0032] According to a preferred embodiment, the second sensor is arranged at the axis with an offset relative to the first sensor when viewed in the direction of the axis, the magnitude of the offset being guided by the number of pole pairs of the sensor array, that is, 90° divided by the number of pole pairs. For example, when the number of pole pairs is 2, the offset is 45°.

[0033] An apparatus according to an embodiment of the invention comprises a drive device, a shaft which can be rotatably driven by the drive device, and a rotation sensor device as described above for determining the bearing position and the rotation direction of the shaft.

[0034] The device is preferably a tool, for example a drilling machine or a milling machine.

[0035] According to a further aspect, a method for carrying out a hysteresis correction for a rotary sensor arrangement is provided, wherein the rotary sensor arrangement has:

[0036] a first sensor unit for generating a first digital sensor signal, the first sensor unit comprising a first sensor arranged at the shaft; and a second sensor unit for generating a second digital sensor signal, the second sensor unit comprising a second sensor arranged at the shaft,

[0037] an evaluation device designed to generate a rotational direction signal indicating the rotational direction of the shaft based on the first digital sensor signal and the second digital sensor signal, wherein the evaluation device is designed to count signal pulses of the first digital sensor signal with a sign that is dependent on the rotational direction and to provide a counter reading,

[0038] The method comprises the following steps:

[0039] - before switching off the rotation sensor device, storing the current signal value of the first digital sensor signal and the current rotation direction;

[0040] upon detecting that the rotation sensor device has been switched on again, comparing the signal value of the first digital sensor signal with a stored signal value of the first digital sensor signal;

[0041] In the event of a discrepancy between the two compared signal values, a correction value is determined based on the difference between the two compared signal values ​​and the stored direction of rotation, and the correction value is added to the counter reading as soon as a first new signal change occurs in the first digital sensor signal after the rotation sensor device is switched on again. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The embodiments are explained in more detail below with reference to the accompanying drawings, wherein:

[0043] Figure 1 A rotation sensor device is shown, which comprises a first sensor unit, a second sensor unit and an evaluation device;

[0044] Figure 2A The first digital sensor signal and the rotation direction signal before shutoff are shown for the case where the shaft rotates in the forward direction;

[0045] FIG. 2B to FIG. 2E The first digital sensor signal and the rotational direction signal after re-activation are shown for four different situations;

[0046] Figure 3A The first digital sensor signal and the rotation direction signal before shutoff are shown for the case where the shaft rotates in the reverse direction;

[0047] FIG. 3B to FIG. 3E The first digital sensor signal and the rotational direction signal after re-activation are shown for four different situations;

[0048] Figure 4 A rotation sensor device having a hysteresis correction device according to the invention is shown;

[0049] Figure 5An electrical device is shown which is equipped with a rotation sensor arrangement according to the invention. DETAILED DESCRIPTION

[0050] The invention relates to a rotation sensor device which is designed to detect the bearing position and the rotation direction of a rotatable shaft. Figure 1 The structure and function of such a rotation sensor device are schematically shown in FIG. A shaft 1 can be identified, which can rotate about its axis of rotation 2. The positive direction of rotation of the shaft 1 is indicated by arrow 3, whereas the negative direction of rotation of the shaft 1 is indicated by arrow 4. Figure 1 In the example shown in , the rotation of the shaft 1 is to be detected with the aid of a magnetic sensor. Therefore, a magnetic flux transmitter 5 connected to the shaft 1 is arranged at or on the shaft 1, and the magnetic flux transmitter has two pole pairs. When the shaft 1 rotates, the magnetic flux transmitter 5 generates a rotating magnetic field. The first magnetic sensor 6 is firmly arranged in a first position relative to the shaft 1 and is designed to detect the rotating magnetic field. The second magnetic sensor 7 is firmly arranged in a second position at the shaft 1 and is also designed to detect the rotating magnetic field. Here, the second magnetic sensor 7 is arranged in a manner twisted by a predetermined angle relative to the first magnetic sensor 6 when viewed in the direction of the rotation axis 2. Figure 1 In the example, the second magnetic sensor 7 is arranged at an offset angle of 45° relative to the first magnetic sensor 6 .

[0051] Preferably, the first magnetic sensor 6 is a first Hall sensor, and the second magnetic sensor 7 is a second Hall sensor. The first magnetic sensor 6 is designed to convert the magnetic flux intensity of the rotating magnetic field into a first analog sensor signal. A first Schmitt trigger circuit 8 is arranged after the first magnetic sensor 6, and the first Schmitt trigger circuit is designed to digitize the first analog sensor signal and provide a first digital sensor signal 9 at the output. The first magnetic sensor 6 and the first Schmitt trigger circuit 8 together form a first sensor unit 10.

[0052] The second magnetic sensor 7 is designed to convert the magnetic flux intensity of the rotating magnetic field into a second analog sensor signal. A second Schmitt trigger circuit 11 is arranged after the second magnetic sensor 7, wherein the second magnetic sensor 7 and the second Schmitt trigger circuit 11 together form a second sensor unit 12. The second Schmitt trigger circuit 11 is configured to digitize the second analog sensor signal and provide a second digital sensor signal 13 at the output. In addition, the Schmitt trigger circuit 11 is used to debounce the sensor signal.

[0053] For the case where shaft 1 rotates in the positive direction, Figure 1, the first digital sensor signal 9 and the second digital sensor signal 13 are plotted as a function of time. It can be seen that a signal pulse of the first digital sensor signal 9 occurs first, and then a signal pulse occurs in the second digital sensor signal 13 with a phase shift of 90° with respect to the signal period. In this regard, it can be inferred from the time sequence of the signal pulses in the first digital sensor signal 9 and in the second digital sensor signal 13 that the shaft 1 rotates in the positive direction according to the arrow 3.

[0054] An evaluation device 14 is provided for evaluating the first digital sensor signal 9 and the second digital sensor signal 13. The evaluation device 14 is designed to determine the direction of rotation of the shaft 1 based on the first digital sensor signal 9 and the second digital sensor signal 13. If, for example, a signal pulse first appears in the first digital sensor signal 9 and then appears in the second digital sensor signal 13 with a phase shift of approximately 90°, the shaft 1 rotates in the forward direction according to arrow 3. If, on the other hand, a signal pulse first appears in the second digital sensor signal 13 and only then in the first digital sensor signal 9, the shaft rotates in the reverse direction according to arrow 4. The evaluation device 14 is designed to generate a rotation direction signal based on the evaluation of the first digital sensor signal 9 and the second digital sensor signal 13, which indicates whether the shaft rotates in the forward direction or in the reverse direction.

[0055] Furthermore, the evaluation device 14 comprises a counter 15 which is designed to count the pulses of the first digital sensor signal 9 in order to thereby detect the number of rotations of the shaft 1. The pulses of the first digital sensor signal 9 are preferably counted with a sign which depends on the direction of rotation. For example, pulses in the forward direction can be counted with a positive sign and pulses in the reverse direction can be counted with a negative sign.

[0056] In the case of sensor units that output digital sensor signals, switching between different signal values ​​of the digital sensor signal is performed based on the signal threshold of the analog-to-digital converter, in this example based on the signal threshold of the Schmitt trigger circuits 8 and 11. In the case of such sensor units, technical difficulties may arise in the switching-on scenario or in the switching-off and re-connection scenario. Even if the magnetic flux intensity detected by the corresponding sensor does not change, switching changes and changes in the signal value may occur in the hysteresis region due to the switching of the internal measuring bridge. This may lead to errors in the counter reading.

[0057] In the following, according to FIG. 2A to FIG. 2E and FIG. 3A to FIG. 3E A method for hysteresis correction is described which accounts for the inaccuracies that occur and thus avoids incremental errors.

[0058] exist Figure 2AThe first digital sensor signal 16 and the rotation direction signal 17 are plotted as a function of time in FIG. The shaft 1 rotates in the positive direction VR, correspondingly the rotation direction signal 17 is at the value "high" (indicated by "H"). The rotation sensor device is switched off shortly before the increment count, e.g. Figure 2A This is shown by the arc in FIG. The switched-off time period is marked with “P”.

[0059] In the context of a switch-off process, if at least one signal change occurred during the preceding switch-on phase, the last signal value of the first digital sensor signal 16 and the direction of rotation signal 17 is stored, for example in a non-volatile memory. If no signal change occurred, the current values ​​do not need to be stored. In order to be able to track whether a signal change occurred during a switch-on cycle that has passed, for example, a status indicator can be set, preferably a flag that is set when a new signal change occurs. During the switch-off process, it is then checked whether the flag is set, and if the flag is set, the current values ​​of the first digital sensor signal 16 and the direction of rotation signal 17 are stored before the switch-off.

[0060] After the switch-off, the rotation sensor device is switched on again, which is indicated by the arc after the switch-off time period "P", wherein FIG. 2B to FIG. 2E Various possible situations that may occur after a restart are shown in FIG.

[0061] exist Figure 2B The first digital sensor signal 18-1 and the rotation direction signal 19-1 after reconnection are plotted as a function of time in FIG. The shaft 1 rotates in the positive direction, so that the rotation direction signal 19-1 jumps to the value "high" after a short time. The signal value of the first digital sensor signal 18-1 has changed compared to the last signal value before switching off. This means that the edge of the first digital sensor signal 18-1 is not detected; there is therefore a lost edge. The initial incremental count is missed, so that the counter reading of the counter 15 has an error of -1. This results in a correction value of +1. However, the correction value of +1 thus obtained is added to the counter reading only when the first new signal change occurs in the first digital sensor signal 18-1 after reconnection. The correction is only considered at this point in time. If the rotation sensor device is switched off again before the first new signal change occurs, the correction value obtained will be discarded and not added to the counter reading. The reason for this procedure is that, upon switching back on, another signal value of the first digital sensor signal 18 - 1 may occur again, for which the determined correction value would then be incorrect.

[0062] exist Figure 2C, which may occur after the rotation sensor device is switched back on, is shown in . The first digital sensor signal 18-2 and the rotation direction signal 19-2 are again shown as a function of time. The shaft 1 continues to rotate in the positive direction here, so that the rotation direction signal 19-2 jumps to the value "high" after a short time. Compared to the situation before the switch-off, the signal value of the first digital sensor signal 18-2 does not change. Figure 2C In the case of , there are then no missing edges and therefore no errors. Figure 2C In the example, the first new signal change 20 occurs at a point in time at which the rotational direction signal 19 - 2 already has the value “high” and is therefore counted with the correct sign, so that the counter 15 is incremented.

[0063] exist Figure 2D and Figure 2E Two possible situations are shown in FIG. 1 when the shaft 1 rotates in the reverse direction after being switched on again. Figure 2D In FIG. 1 , the first digital sensor signal 18-3 and the rotation direction signal 19-3 are plotted as a function of time after the reconnection. The rotation direction signal 19-3 jumps to the value "low" (indicated by "L") after a certain time and thus indicates a reverse rotation RR of the shaft 1. The signal value of the first digital sensor signal 18-3 corresponds to the signal value before the switch-off; in FIG. Figure 2D In the case of , there are therefore no missing edges and therefore no errors. At the point in time at which the first new signal change 21 occurs, the rotation direction signal 19-3 already has the value "low", so that the first new signal change 21 has already been counted with a negative sign, and the counter is then decremented. Figure 2D In the case shown in , no error occurs and therefore no correction is required.

[0064] exist Figure 2E 1 shows another possible situation after the rotation sensor device has been switched back on. The first digital sensor signal 18-4 and the rotation direction signal 19-4 after the switch-on are plotted as a function of time. Since the shaft 1 rotates in the reverse direction, the rotation direction signal 19-4 jumps to the value "low" after a certain period of time. Figure 2EIt can be recognized that the signal value of the first digital sensor signal 18-4 after reconnection is not consistent with the signal value before switching off. This means that the initial edge in the first digital sensor signal 18-4 is not detected; therefore, there is a lost edge. The initial incremental count of the counter is missed. In this regard, the counter reading has an error of -1, and the correction value is then +1. This correction value is not added to the counter reading of the counter 15 immediately, but only when the first new signal change 22 occurs. At the point in time at which the first new signal change 22 occurs, the rotation direction signal 19-4 already has the value "low", which indicates that the shaft is rotating in the opposite direction. Therefore, the first new signal change 22 is counted with a negative sign, and the counter counts down by 1. In addition, the correction value of +1 caused by the lost edge is added to the counter reading.

[0065] When the rotary sensor device is switched off again, it is checked whether at least one new signal change has occurred in the first digital sensor signal within the previous switch-on period. This can be detected, for example, by setting the flag already mentioned above when such a signal change occurs for the first time. If at least one signal change has occurred since the last switch-on, in the context of the switch-off process before the rotary sensor device is switched off, not only the current value of the first digital sensor signal but also the value of the rotational direction signal is stored, for example in a non-volatile memory.

[0066] exist FIG. 3A to FIG. 3E FIG. 4 shows a further situation which may occur during switching off and subsequently switching on again for the case where the shaft is initially rotated in the reverse direction RR.

[0067] exist Figure 3A The first digital sensor signal 23 and the rotation direction signal 24 are plotted as a function of time in FIG. The rotation sensor device is switched off shortly before the count is decremented. Figure 3A . The shaft 1 rotates in the reverse direction before the switch-off, so that the rotational direction signal 24 has the value "low". In the framework of the switch-off process, if at least one signal change of the first digital sensor signal 23 occurred during the previous switch-on phase, the last signal value of the first digital sensor signal 23 and the rotational direction signal 24 are stored.

[0068] After the switch-off, the rotation sensor device is switched on again, wherein FIG. 3B to FIG. 3E Various possible situations that may occur after a restart are shown in FIG.

[0069] exist Figure 3B In FIG. 2 , the first digital sensor signal 25 - 1 and the rotation direction signal 26 - 1 after the re-energization are plotted as a function of time. Figure 3BIn the situation shown in , the shaft rotates in the positive direction after the reconnection. The direction of rotation signal 26-1 therefore has the value "high" after a certain time. The signal value of the first digital sensor signal 25-1 after the reconnection corresponds to the signal value before the switch-off. Figure 3B There are no missing edges and therefore no errors in the first digital sensor signal 25-1. Figure 3B In general, Figure 3B There is no problem in the situation shown in .

[0070] exist Figure 3C The first digital sensor signal 25-2 and the rotation direction signal 26-2 after the re-activation are plotted as a function of time in FIG. Figure 3C In the situation shown in , the shaft also rotates in the positive direction after reconnection. The direction of rotation signal 26-2 jumps to the value "high" after a certain time. The signal value of the first digital sensor signal 25-2 after reconnection differs from the signal value before switching off. The initial falling edge is not detected. Figure 3C There is then a missing edge in the counter reading. Since the initial decrement count is missed, the counter reading has an error of +1, which leads to a correction value of -1. However, this correction value is not added to the current counter reading immediately, but only when the first new signal change 27 occurs in the first digital sensor signal 25-2. At the point in time at which the first new signal change 27 occurs, the rotation direction signal 26-2 is already at the value "high", so that the first new signal change 27 has been counted with a positive sign. In addition, the correction value of -1 is also added to the counter reading at the point in time at which the first new signal change 27 occurs. If the rotation sensor device has been switched off again before the first new signal change occurs, the correction value will be discarded and not added to the counter reading.

[0071] exist Figure 3D and Figure 3E 2 shows what occurs when the shaft rotates in the reverse direction after being switched back on. Figure 3DThe first digital sensor signal 25-3 and the rotation direction signal 26-3 after reconnection are shown as a function of time. After the shaft rotates in the reverse direction, the rotation direction signal 26-3 jumps to the value "low" after a certain time. The signal value of the first digital sensor signal 25-3 after reconnection is not consistent with the signal value before switching off. The initial falling edge is not detected, so there is a missing edge. Because the initial decrement count is missed, there is an error of +1 for the counter reading, so the correction value is -1. However, only when the first new signal change 28 of the first digital sensor signal 25-3 occurs, the correction value is added to the counter reading of the counter 15. At the time point where the first new signal change 28 occurs, the correction value of -1 is added to the counter reading. At the time point where the first new signal change 28 occurs, the rotation direction signal 26-3 already has the value "low", so the first new signal change 28 is counted with a negative sign.

[0072] exist Figure 3E A further situation is shown in FIG. after the rotation sensor device has been switched back on. Figure 3E The first digital sensor signal 25-4 and the rotation direction signal 26-4 are plotted as a function of time after the reconnection. The shaft rotates in the reverse direction, so that the rotation direction signal 26-4 has the value "low" after a certain time. The signal value of the first digital sensor signal 25-4 after the reconnection corresponds to the signal value before the switch-off, in this respect. Figure 3E There are no missing edges and no errors in . The first new signal change 29 has been counted with a negative sign. Overall, Figure 3E No problems occurred that required correction.

[0073] exist Figure 4 , a block diagram of a rotation sensor device 30 is shown, which has a hysteresis correction device 31. The rotation sensor device 30 further comprises an energy supply 32, a magnetic flux transmitter 33, a first magnetic sensor 34 and an analog-to-digital converter 35, which can, for example, comprise a Schmitt trigger circuit. The first magnetic sensor 34 is designed to detect a changing magnetic field generated by the magnetic flux transmitter 33 and to generate a first analog sensor signal 36. The analog-to-digital converter 35 is designed to convert the first analog sensor signal 36 of the first magnetic sensor 34 into a first digital sensor signal 37. The first digital sensor signal 37 and the rotation direction signal 38 are supplied to the hysteresis correction device 31. In addition, the hysteresis correction device 31 is connected to the energy supply 32 in order to detect the switching on and off of the rotation sensor device 30. Based on the mentioned input signal, the hysteresis correction device 31 generates a hysteresis correction signal 39 for correcting errors caused by hysteresis.

[0074] A rotation sensor device having a hysteresis correction device according to an embodiment of the present invention can be used, for example, in an electrical device, such as a tool. Figure 5 Such an electric instrument 40 is shown in FIG. The electric instrument 40 comprises a circuit 41 and an electric drive 42, which drives a shaft 43. The circuit 41 comprises a microcontroller 44 and a power output stage 45. The voltage preset for the electric drive 42 is selected according to the user's wishes. The signal that is usually detected continuously is used for voltage detection. The rotation sensor device according to an embodiment of the present invention is used for angle / rotation speed detection. For this purpose, a first sensor unit 46 and a second sensor unit 47 are arranged at the shaft 43. An evaluation device 48 with a hysteresis correction device is implemented on the circuit 41. Here, the hysteresis correction device can exist in the form of a code written for the microcontroller 44, for example.

[0075] The features disclosed in the preceding description, the claims and the drawings may be essential both individually and in any combination for the realization of the invention in its various embodiments.

Claims

1. A rotation sensor device (30) for determining the bearing position and the rotation direction of a rotatable shaft (1), wherein: The rotation sensor device (30) comprises: a first sensor unit (10) for generating a first digital sensor signal (9, 16, 23), the first sensor unit comprising a first sensor arranged at the shaft (1); and a second sensor unit (12) for generating a second digital sensor signal (13), the second sensor unit comprising a second sensor arranged at the shaft (1); an evaluation device (14) designed to generate a rotation direction signal (17, 24) indicating the rotation direction of the shaft (1) based on the first digital sensor signal and the second digital sensor signal, wherein the evaluation device (14) is designed to count signal pulses of the first digital sensor signal (9, 16, 23) with a sign that depends on the rotation direction and to provide a counter reading; The rotation sensor device (30) comprises a hysteresis correction device (31), wherein the hysteresis correction device has: a storage device, which is designed to store the current signal value of the first digital sensor signal (9, 16, 23) and the current direction of rotation before the rotation sensor device (30) is switched off; a comparison device, which is designed to compare the signal value of the first digital sensor signal (9, 16, 23) with the signal value of the first digital sensor signal stored by the storage device when the rotation sensor device (30) is detected to be switched on again; - A correction device, which is designed to determine a correction value based on the difference between the two compared signal values ​​and the rotation direction stored by the storage device in the event of a difference between the two signal values, wherein the correction device is designed to add the correction value to the counter reading as soon as a first new signal change (20-22, 27-29) occurs in the first digital sensor signal (9, 16, 23) after the rotation sensor device (30) is switched on again.

2. The rotation sensor device (30) according to claim 1, characterized in that The first sensor is a first magnetic sensor (6), in particular a Hall sensor, and / or the second sensor is a second magnetic sensor (7), in particular a Hall sensor.

3. The rotation sensor device (30) according to claim 1 or claim 2, characterized in that: The first sensor is designed to generate a first analog sensor signal, wherein the first sensor unit (10) comprises a first Schmitt trigger circuit (8) which is designed to convert the first analog sensor signal into the first digital sensor signal (9, 16, 23).

4. The rotation sensor device (30) according to any one of claims 1 to 3, characterized in that The second sensor is designed to generate a second analog sensor signal, wherein the second sensor unit (12) comprises a second Schmitt trigger circuit (11) which is designed to convert the second analog sensor signal into the second digital sensor signal.

5. The rotation sensor device (30) according to any one of claims 1 to 4, characterized in that The evaluation device (14) is designed to count first new signal changes (20-22, 27-29) of the first digital sensor signal (9, 16, 23) with a sign that is dependent on the current direction of rotation, starting from when the rotation sensor device (30) is switched back on.

6. The rotation sensor device (30) according to any one of claims 1 to 5, characterized in that The rotation sensor device (30) comprises a state indicator, wherein the hysteresis correction device (31) is configured to reset the state indicator when the rotation sensor device (30) is switched on, to set the state indicator when a first new signal change (20-22, 27-29) of the first digital sensor signal (9, 16, 23) occurs after the switching on, and to store current values ​​of the first digital sensor signal (9, 16, 23) and of the rotation direction signal (17, 24) when the state indicator is set when the rotation sensor device (30) is switched off.

7. An apparatus (40) comprising: - a driving device (42); - a shaft (1, 43) rotatably drivable by said drive means (42); - A rotation sensor device (30) according to any one of claims 1 to 6.

8. A method for performing hysteresis correction for a rotation sensor device (30), wherein: The rotation sensor device (30) comprises: a first sensor unit (10) for generating a first digital sensor signal (9, 16, 23), the first sensor unit comprising a first sensor arranged at the shaft (1); and a second sensor unit (12) for generating a second digital sensor signal (13), the second sensor unit comprising a second sensor arranged at the shaft (1); an evaluation device (14) designed to generate a rotation direction signal (17, 24) indicating the rotation direction of the shaft (1) based on the first digital sensor signal and the second digital sensor signal, wherein the evaluation device (14) is designed to count signal pulses of the first digital sensor signal (9, 16, 23) with a sign that depends on the rotation direction and to provide a counter reading, The method comprises the following steps: - before switching off the rotation sensor device (30), storing the current signal value of the first digital sensor signal (9, 16, 23) and the current rotation direction; - when it is detected that the rotation sensor device (30) has been switched on again, comparing the signal value of the first digital sensor signal (9, 16, 23) with a stored signal value of the first digital sensor signal; - in the event of a difference between the two compared signal values, a correction value is determined based on the difference between the two compared signal values ​​and the stored direction of rotation, and the correction value is added to the counter reading as soon as a first new signal change (20-22, 27-29) occurs in the first digital sensor signal (9, 16, 23) after the rotation sensor device (30) is switched on again.

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