Calibration device for generating calibration data for an optical rotary encoder

Abstract

Calibration device (1) for generating calibration data for an optical rotary encoder (100), wherein the optical rotary encoder (100) comprises first sensor means (111), a code disk (101), a correction unit (112), and non-volatile storage means (114), wherein the code disk (101) is fixed on a rotatable shaft (200), and the first sensor means (111) are configured to interact with the code disk (101) at a first angular position (α_1) such that an angular change of the shaft (200) can be detected and a first rotational angle signal (phi_1) for representing a rotational movement of the shaft (200) can be determined, and wherein the correction unit (112) is configured to correct the first rotational angle signal (phi_1) using the calibration data, comprising - second sensor means (2) which are arranged in a measuring state (20) of the adjustment device (1) to interact with the code disk (101) such that a second rotation angle signal (phi_2) can be determined; - Handling means (5) designed to adjust the relative position of the second sensor means (2) and / or the code disk (101) between the measuring state (20) and a rest state (21) such that in the measuring state (20) the second sensor means (2) interact with the code disk (101) at a second angular position (α_2) and that in the rest state (21) the second sensor means (2) are spaced away from the code disk (101) in such a way that they are not in operative connection, wherein the second angular position (α_2) of the second sensor means (2) differs from the first angular position (α_1) of the first sensor means (1); - Communication means (6) that enable data exchange between the alignment device (1) and the optical rotary encoder (100) such that at least the first rotation angle signal (phi_1) and the generated calibration data can be transmitted; - Computing means (7) which are designed such that the calibration data can be determined from the first rotation angle signal (phi_1) and the second rotation angle signal (phi_2) according to an assignment rule, characterized in that the adjustment device (1) comprises a distance sensor (10), wherein the distance sensor (10) is designed such that a distance signal for mapping the distance between the second sensor means (2) and the code disk (101) can be generated and made available for the handling means (5).

Description

[0001] The present invention relates to a calibration device for generating calibration data for an optical rotary encoder according to claim 1.

[0002] Optical encoders are used to detect the rotational movement of a rotating shaft. Known optical encoders comprise a code disk that is fixed to the shaft being monitored. Furthermore, the encoders include sensor elements designed to read a code track on the code disk. The code disk and the sensor elements are designed to be movable relative to each other. The encoder can thus detect changes in the shaft's angle and generate a rotational angle signal to represent the shaft's rotational movement.

[0003] For high signal quality of the rotation angle signal, tolerance limits between the sensor elements and the code disk rotating with the shaft must be maintained. However, an asymmetry in the relative motion of the object and the sensor elements can exist, caused, for example, by mechanical tolerances in the area of ​​the code disk or by a runout or wobble error of the shaft.

[0004] A runout error occurs if the axis of rotation of the code disc, after mounting it on the shaft, does not correspond to the original center of rotation of the code track formed in the code disc. To compensate for the influence of the runout error on the rotational angle signal, a calibration using a reference encoder is currently performed to determine internal calibration data for the respective optical encoder. This data is then stored in the encoder to correct the rotational angle signal. Calibration with the reference encoder is extremely time-consuming, as it must be performed on every shaft or in every manufactured motor. Therefore, the previously common method of encoder calibration using a reference encoder results in high production costs.

[0005] It is also generally known to use a reference encoder to generate special calibration data for the respective optical encoder in order to correct a wobble error that can occur if the code disk is not aligned exactly perpendicular to the axis of rotation and thus has a runout deviation.

[0006] The present invention aims to overcome the disadvantages known from the prior art. In particular, it aims to provide a way to simplify the generation of sensor-specific calibration data for correcting rotation angle signals.

[0007] EP 1 923 670 B1 discloses a rotary encoder with a code disc having a code track and first sensor means for reading the code track. The first sensor means are connected to an evaluation unit that stores correction values. The correction values ​​are determined during calibration by comparing the measured values ​​of the first sensor means with measured values ​​of additional, second sensor means. The second sensor means are temporarily positioned relative to the code disc to determine the correction values. After calibration, the correction values ​​are used to improve the measured values ​​of the first sensor means.

[0008] US Patent 11,579,001 B2 discloses a calibrator and a rotary encoder, wherein the encoder measures the rotational position of a shaft. The encoder comprises a code disk attached to the shaft and several sensor means that scan the code disk at different positions. The first sensor means generate a signal used to calculate the position. The second and subsequent sensor means help detect errors in the measurements by also outputting signals. This error information is stored in a memory and used to correct the position. The code disk includes incremental as well as absolute patterns, which are reflective or transparent.

[0009] US Patent 9,046,384 B2 discloses a method for self-calibrating a rotary encoder. The rotary encoder has a code disk and first and second sensor means that read the code track of the code disk at different positions.

[0010] The problem is solved by an adjustment device according to claim 1 according to the invention.

[0011] The calibration device according to the invention is designed to generate calibration data for an optical rotary encoder.

[0012] Such an optical rotary encoder comprises first sensor means and a code disk which can be fixed on a rotatable shaft and is movable relative to the statically fixed first sensor means of the optical rotary encoder in the mounted and / or fixed state.

[0013] In the present invention, statically fixed with respect to the first sensor means means that the rotary encoder is designed such that the relative distance between the first sensor means and the code disk, in particular along a Z-direction, is fixed and / or not automatically adjustable.

[0014] The first sensor elements are designed to interact with the code disk at a first angular position, thus enabling the detection of any change in the shaft's angle. These first sensor elements are configured to generate an initial rotational angle signal to represent the shaft's rotational movement.

[0015] Furthermore, such rotary encoders also include a correction unit to correct the generated rotation angle signal based on the calibration data.

[0016] The calibration data preferably include a magnitude and a phase to compensate for a sinusoidal error. In the present invention, a sinusoidal error refers to an angular error. The sinusoidal error is, in particular, the result of a mechanical runout error or a mechanical wobble error.

[0017] Furthermore, the rotary encoder includes non-volatile storage media for recording the calibration data.

[0018] In the case of a sinusoidal error caused by a runout error, the period of the error corresponds to one full rotation of the code disk. In other words, the frequency of the error corresponds to the frequency of the code disk's rotation.

[0019] Using the calibration data, the correction unit of the rotary encoder determines a suitable correction value for each detected angle value of the rotary angle signal in order to correct the rotary angle signal.

[0020] The calibration data thus enables the determination of a correction value by calculating an angular function, such as the cosine, taking into account the magnitude, phase, and period of the sinusoidal error. This correction value is then subtracted from the measured angle value to obtain the corrected angle value, in particular the corrected rotation angle signal, from the initial rotation angle signal.

[0021] In the case of a sinusoidal error caused by a wobble, the period of the error corresponds to half the period of the rotation. In other words, the frequency of the error is twice the frequency of the code disk's rotation.

[0022] Preferably, the calibration data stored in the non-volatile memory comprises several sinusoidal errors, each defined by magnitude, phase, period, and / or frequency. The correction unit in the rotary encoder can thus correct the angular signal using the correction value resulting from the sum of the several calculated trigonometric functions.

[0023] It is particularly preferred if a first error signal e_1 in the rotary encoder is determined via first calibration data using the following relationship: e_1=Amount_1*cos(1*phi_1+phase_1), where the runout error is characterized by its magnitude and phase. In other words, the calibration data in this case includes the value for magnitude_1 and the value for phase_1. The first error signal e_1 thus forms a first correction value.

[0024] It is particularly preferred if a second error signal e_2 is determined via second calibration data according to the following relationship: e_2=Amount_2*cos(2*phi_1+phase_2), This assignment rule allows the error signal e_2 to be corrected by its magnitude and phase to correct the component caused by the wobble error. In other words, the calibration data in this case includes the value for magnitude_2 and the value for phase_2. The second error signal e_2 thus constitutes a second correction value.

[0025] The following relationship applies to the total error e(phi_1) and / or a total correction value: e(phi_1)=e_1+e_2;

[0026] The correction unit then uses the total error to correct the first rotation angle signal (phi_1). The total error, or total correction value, is then subtracted from the measured angle value to determine the corrected angle value, specifically the corrected rotation angle signal, from the first rotation angle signal.

[0027] The calibration data are therefore preferably angle-dependent.

[0028] The calibration data is preferably stored in non-volatile memory in the form of a table, particularly a lookup table, specifically as a multitude of individual values, each corresponding to a correction value for different ranges of the rotation angle signal phi_1. The corrected rotation angle signal can thus be determined by subtracting the respective correction value from the lookup table from the corresponding rotation angle signal phi_1.

[0029] By using a lookup table in the rotary encoder, calculating the correction value by applying one or more trigonometric functions within the encoder is unnecessary. A corresponding memory area for the lookup table is provided in the non-volatile memory for this purpose.

[0030] Advantageously, the first rotary angle signal of the encoder can be corrected using the calibration data to eliminate a component of the error. This component of the error is caused in particular by runout errors and / or wobble errors and / or asymmetrical rotational movement of the code disk mounted on the shaft relative to the first sensor elements of the optical encoder.

[0031] The calibration device according to the invention comprises at least two sensor means which, in a measuring state of the calibration device, are configured to interact with the code disk in order to determine a second rotation angle signal of the shaft. The second sensor means are preferably identical in construction to the first sensor means of the rotary encoder.

[0032] In other words, the second sensor means are arranged at a second angular position in the measuring state of the calibration device. Within the scope of the present invention, this means that, viewed from above, the first sensor means are fixed at a first angular position and the second sensor means at a second angular position, thus detecting the rotational movement of the code disk and / or the shaft at the respective angular position.

[0033] The adjustment device according to the invention also comprises handling means designed to adjust the relative position of the second sensor means and / or the code disc between the measuring state and a rest state, such that in the measuring state the second sensor means interact with the code disc at the second angular position of the code disc and that in the rest state the second sensor means are spaced away from the code disc in such a way that they are not in operative connection, wherein the second angular position of the second sensor means differs from the first angular position of the first sensor means.

[0034] In other words, the handling means, which are preferably designed as a robot arm and / or a support arm and / or a mechanical lifting and / or swiveling device and / or a swiveling and / or lifting arm, are designed and / or configured such that the relative position between the second sensor means and the code disk and / or the relative position between the second sensor means and the first sensor means can be changed. This advantageously allows the second sensor means to be adjustable and / or movable into the measuring state in order to bring the second sensor means into operative contact with the code disk in the second rotational angle signal and thus also to bring them relative to the first sensor means arranged in the first rotational angle position.The first rotation angle signal thus represents the rotational movement of the code disk at the first rotation angle position, and the second rotation angle signal represents the rotational movement of the code disk at the second rotation angle position, which is why asymmetrical rotational movements can be detected and measured.

[0035] The second sensor means are therefore not statically fixed. In the present invention, "not statically fixed" with respect to the second sensor means means that the relative distance between the second sensor means and the code disk, particularly along a Z-direction, is not fixed and / or adjustable by means of the handling means. In other words, unlike the first sensor means, the second sensor means are thus movable translationally and / or with respect to the Z-direction.

[0036] The calibration device according to the invention further comprises communication means that enable data exchange between the calibration device and the optical rotary encoder, such that at least the first rotation angle signal and the generated calibration data can be transmitted.

[0037] The communication means preferably comprise a bidirectional data connection, in particular an SPI bus or a CAN bus or a BiSS interface, to reliably exchange information between the calibration device according to the invention and the rotary encoder to be calibrated via a standardized communication protocol. Preferably, the communication means are designed for wireless data exchange.

[0038] Preferably, the connection of the communication means to the optical rotary encoder is permanently disconnected after the exchange of the calibration data, since the calibration data is stored in the non-volatile storage media of the optical rotary encoder.

[0039] The calibration device according to the invention further comprises computing means which are designed such that the calibration data for the optical rotary encoder can be determined from the first rotation angle signal and the second rotation angle signal according to an assignment rule.

[0040] The computing devices are designed in particular as a DSP or a microcontroller or as an ASIC and include in particular a computing unit for performing arithmetic operations.

[0041] The assignment rule includes in particular a weighting and / or consideration of the first rotation angle signal and at least the second rotation angle signal according to the respective angular position in order to determine the calibration data.

[0042] Particularly preferred are the computational instruments designed in such a way that the magnitude and phase of different period lengths or frequencies can be determined as calibration data.

[0043] The computational means can thus provide the calibration data directly to the rotary encoder in the form of a table, in particular a look-up table, which contains correction values ​​for different values ​​of the rotation angle signal phi_1, or in the form of magnitude, phase and period or frequency of selected sinusoidal errors, in particular runout errors and / or wobble errors.

[0044] The code disc preferably includes a reference mark or has a code track with absolute position, for example, an absolute track. Advantageously, a full rotation of the shaft can thus be uniquely identified.

[0045] The calibration data can be determined in particular by different assignment rules.

[0046] The allocation rules for adjusting for a runout error preferably comprise the following calculation steps, where phi_1 is the first rotation angle signal of the first sensor means at a specific time and phi_c is an auxiliary quantity and / or the error-corrected rotation angle signal. It should be noted that phi_1 = phi1 and phi_2 = phi2. phi_c=phi1+phi2−180°2

[0047] Furthermore, it is pointed out that phi_1 in particular describes the time course of the first rotation angle signal of the first sensor means, and phi_2 in particular describes the time course of the second rotation angle signal of the second sensor means.

[0048] Here, the first angular position of the first sensor means is: α_1 = 0° and the second angular position α_2 of the second sensor means is: α_2 = 180°.

[0049] Accordingly, the relationship can also be described by phi_c=phi1+phi2−α_22 be described.

[0050] When adding rotation angle signals, especially the rotation angle signals phi_1 and phi_2, the respective overflow of the signals must be taken into account so that no unwanted jumps form in the resulting signal.

[0051] For example, before applying the assignment rule, the individual rotation angle signals can be extended by adding or subtracting 360° if an overflow occurs, thus preventing an overflow during the calculation. Alternatively, an angular velocity can be calculated for each signal, and these angular velocities can then be added and scaled. By integrating this result while considering the initial condition of phi_1, the rotation angle signal phi_c can then be calculated.

[0052] If the rotational movement of the shaft is detected not only by the first and second sensor means, but also by a third sensor means, the following relationship applies, assuming the sensor means are positioned evenly distributed along the circumference of the shaft. Thus, the first angular position of the first sensor means is α_1 = 0°, the second angular position of the second sensor means is α_2 = 120°, and the third angular position of the third sensor means is α_3 = 240°. It should be noted that φ_1 = φ1, φ_2 = φ2, and φ_3 = φ3. phi_c=phi1+phi2−α_2+phi3−α_33

[0053] Here, phi_c is the error-corrected rotation angle signal, phi_1 is the rotation angle signal of the first sensor means, phi_2 is the rotation angle signal of the second sensor means, and phi_3 is the rotation angle signal of the third sensor means.

[0054] If the rotational movement of the shaft is detected not only by the first, second, and third sensor means, but also by a fourth sensor means, the following relationship applies, where all sensor means are preferably again uniformly distributed around the circumference of the shaft and / or code disk. Thus, the angular position of the first sensor means is α_1 = 0°, the angular position of the second sensor means is α_2 = 180°, the angular position of the third sensor means is α_3 = 90°, and the angular position of the fourth sensor means is α_4 = 270°. It should be noted that phi_1 = phi1, phi_2 = phi2, phi_3 = phi3, and phi_4 = phi4. applies. phi_c=phi1+phi3−α_3+phi2−α_2+phi4−α_44

[0055] Here, phi_c is the error-corrected rotation angle signal, phi_1 is the rotation angle signal of the first sensor means, phi_2 is the rotation angle signal of the second sensor means, phi_3 is the rotation angle signal of the third sensor means, and phi_4 is the rotation angle signal of the fourth sensor means.

[0056] Furthermore, it is preferred to determine the constants α_2 and / or α_3 and / or α_4 metrologically such that, when the rotation angle signal phi_1 assumes the value zero, the angular positions then measured, phi_2 and / or phi_3 and / or phi_4, are used as the value for α_3 and / or phi_4. In other words, with this configuration, phi_c is equal to zero when phi_1 is zero.

[0057] The error signal e between the rotation angle signal of the first sensor means phi_1 and the error-corrected rotation angle signal phi_c can therefore be determined as follows: e=phi_1−phi_c

[0058] The corrected rotation angle signal of the rotary encoder phi_1_c then results from the following difference: phi_1_c=phi_1−e; It is particularly preferred that the error signal e is stored in the optical encoder via the calibration data, in particular as support points, preferably as rotation-angle-dependent support points in a table, especially in a look-up table, or via the magnitude and phase of certain sinusoidal errors, in particular harmonics, with respect to one revolution. The look-up table contains a defined and / or predetermined number of discrete individual values ​​per full revolution. Each discrete individual value thus represents a correction value for a partial angular range of the rotation-angle signal. The respective individual values ​​of the rotation-angle partial ranges can be determined from the error signal e by interpolation, in particular by "nearest neighbor" or linear interpolation.Furthermore, it is preferred if the error signal e between the rotation angle signal of the first sensor means phi_1 and the error-corrected angle signal phi_c is alternatively determined by determining the mean value mean of the difference between the first rotation angle signal and the error-corrected angle signal as follows:. e=(phi_1−phi_c)−mean(phi_1−phi_c).

[0059] Advantageously, such an implementation and / or assignment rule allows for the compensation of mounting tolerances of the sensor elements with respect to the individual angular positions. Thus, there is no negative impact if the first, second, third, and / or fourth angular positions do not correspond to the assumed target angular position of 90°, 180°, 120°, and / or 240°. Accordingly, when applying the mean value, it is not necessary to consider the static angular offsets, α_2, α_3, α_4, of the second sensor elements when calculating phi_c. Furthermore, it is preferably provided that the correction function and / or the assignment rule comprises multiple stages and / or several steps. It is particularly preferred if the correction function is structured and / or implemented in two stages.

[0060] In further training, it is particularly preferred if the magnitude and phase of selected sinusoidal errors are determined from the error signal e and provided as calibration data for the rotary encoder.

[0061] By applying a DFT, the computational tools can convert the error signal e into calibration data in magnitude, phase and period length or frequency.

[0062] The computing tools can thus provide the calibration data directly to the rotary encoder in the form of a table, in particular a look-up table, or in the form of magnitude, phase and period or frequency of selected sinusoidal errors, in particular runout errors and / or wobble errors.

[0063] By using a look-up table in the rotary encoder, it is not necessary to calculate the correction value by applying one or more trigonometric functions in the rotary encoder; however, a corresponding non-volatile memory area must be provided in the storage means for the look-up table.

[0064] As a result, it was discovered within the scope of the present invention that the generation of calibration data can be significantly simplified by the adjustment device according to the invention. This is achieved by a clever combination of the first sensor means with the second sensor means in order to determine the calibration data.

[0065] Advantageous embodiments of the invention are described in the dependent claims. The scope of the invention includes all combinations of at least two features disclosed in the description, the claims, and / or the figures.

[0066] A preferred embodiment provides that the second sensor means comprise light-generating means for emitting light beams and light-detection means for detecting light beams, particularly those reflected from the code disk. The light-generating means particularly preferably include an LED as the light source. The light-detection means most preferably include at least one photodiode to detect the proportion of reflected light beams.

[0067] It is further noted that the first sensor means also include, in particular, light-generating means for emitting light rays and light-detection means for detecting light rays.

[0068] A preferred embodiment provides that the light-generating means and the light-sensing means are positioned adjacent to and opposite the front of the code disk, at least during the measurement state. This adjacent positioning of the light-generating and light-sensing means simplifies the design of the interaction between the calibration device according to the invention and the code disk, which has a beneficial effect on the cost and time required to perform a calibration using the calibration device according to the invention.

[0069] In a preferred development, the code disk is designed such that incident light rays are reflected either to a high or a low degree. The code disk thus comprises areas with high reflectivity and areas with low reflectivity to form the code track. Alternatively, the code disk can also have areas that are transparent and opaque to light rays. The code track is formed in the code disk in a generally known manner by these different areas.

[0070] A particularly preferred embodiment provides that the code disc comprises a code track consisting of weakly and strongly reflective areas, preferably black and silver-colored chrome areas, which are positioned adjacent to each other and alternating within the code disc to form the code track. The black chrome areas thus generate a low proportion of reflected light rays, while the silver-colored chrome areas generate a high proportion of reflected light rays.

[0071] A preferred further development provides that the handling means are designed such that, in the measurement state, the second angular position of the second sensor means is selected such that the first and second sensor means are positioned essentially rotated by 180° when viewed from above the code disc. In other words, the first sensor means thus detect the rotational movement of the shaft at the first angular position of 0°, and the second sensor means detect the rotational movement of the shaft at the second angular position of 180°. Advantageously, this allows even an asymmetrical rotational movement of the shaft to be detected with minimal sensor technology and therefore cost-effectively, in order to generate the calibration data that already enables the correction of the runout error.

[0072] A preferred further development provides that the handling means include third and / or fourth sensor means. In this context, the handling means are designed such that, in the measurement state, the third sensor means interact with the code disc at a third angular position and the fourth sensor means interact with the code disc at a fourth angular position.

[0073] With a total of four sensor means, this specifically means that, in a top view of the code disk, the first sensor means are positioned rotated from the third sensor means by essentially 90°, the first sensor means from the fourth sensor means by essentially 270°, and the first sensor means from the second sensor means by essentially 180°.

[0074] In other words, the first set of sensors detects the rotational movement of the shaft at the first angular position of 0°, the second set of sensors detects the rotational movement of the shaft at the second angular position of 180°, the third set of sensors detects the rotational movement of the shaft at the third angular position of 90°, and the fourth set of sensors detects the rotational movement of the shaft at the fourth angular position of 270°. Advantageously, this allows not only runout errors but also other disturbances, such as the negative influence of wobble.

[0075] With a total of three sensor means, this specifically means that, in a top view of the code disk, the first sensor means are positioned rotated from the second sensor means by essentially 120° and the first sensor means are rotated from the third sensor means by essentially 240°.

[0076] In other words, the first sensor means thus detect the rotational movement of the shaft at the first angular position of 0°, the second sensor means detect the rotational movement of the shaft at the second angular position of 120°, and the third sensor means detect the rotational movement of the shaft at the third angular position of 240°.

[0077] The third and / or fourth sensor means are not statically fixed, as is the case with the second sensor means. In the present invention, "not statically fixed" with respect to the third and / or fourth sensor means means that the relative distance between the third and / or fourth sensor means and the code disk, particularly along a Z-direction, is not fixed and / or adjustable by means of the handling means. In other words, unlike the first sensor means, the third and / or fourth sensor means are thus movable translationally and / or with respect to the Z-direction.

[0078] According to the invention, the adjustment device comprises a distance sensor, the distance sensor being configured such that a distance signal for mapping the distance between the second sensor means and the code disk can be generated and made available to the handling means. The handling means can thus influence the relative distance between the second sensor means and the code disk depending on an output signal from the distance sensor.

[0079] A preferred further development provides that the adjustment device includes at least one positioning pin designed to engage in a recess and / or bore of the optical rotary encoder, such that the relative position of the second sensor means to the code disk and / or to the first sensor means, in particular with respect to an XY plane oriented transversely to the Z direction, can be determined and / or precisely defined.

[0080] Preferably, the positioning pin extends along a Z-direction, and the handling means are designed such that the second sensor means are also translationally adjustable along the Z-direction when moving into the measuring state. Advantageously, this allows for precise positioning of the second sensor means—and any other sensor means of the calibration device—relative to the first sensor means and / or relative to the code disk in the measuring state.

[0081] The recess provided for receiving the positioning pin is preferably formed in the circuit board of the optical rotary encoder and / or in a housing part of the electric motor encompassing the shaft.

[0082] In this context, it is preferably provided that this bore is encompassed by an electric motor that includes the shaft. Particularly preferably, the bore is thus formed in the bearing shield of the motor.

[0083] The bore preferably has a relative position to the first sensor means.

[0084] A preferred further development provides that the handling means are designed as a swivel arm, such that the relative position between the second sensor means and the code disk can be changed in three dimensions, in particular in the XY plane and in a Z plane running transversely to it.

[0085] In a preferred embodiment, the handling means are designed as a swivel and / or lifting arm such that the relative distance of the second sensor means—and any further sensor means of the calibration device—to the axis of rotation of the shaft and / or the code disk fixed on the shaft can be adjusted in order to adapt the position of the second sensor means—and any further sensor means—to the dimensions of the code disk. Advantageously, the calibration device according to the invention can thus be used in a production facility for the fully automated calibration of optical rotary encoders with code disks of different sizes. This makes the calibration device universally applicable, which enables further cost savings.

[0086] A preferred further development approach stipulates that the computing tools are designed such that the assignment rule processes the respective rotation angle signals depending on their respective angular positions to determine the calibration data. Specifically, this means that the first rotation angle signal is processed depending on the first angular position, and the second rotation angle signal is processed depending on the second angular position, in order to determine the calibration data. This also applies in particular to any third and fourth sensor elements, whose third and fourth rotation angle signals are then also evaluated according to their third and fourth rotation angle positions.

[0087] Furthermore, within the scope of the present invention, protection is claimed for an electric motor comprising a shaft and an optical encoder with a code disk. The code disk is fixed to the shaft of the motor. The optical encoder is also configured to interact with the calibration device according to the invention and, in particular, includes calibration data that can be generated by the calibration device according to the invention in order to correct the first rotation angle signal with respect to an error component.

[0088] Such a proportion of errors is caused in particular by a runout error and / or a wobble error and / or other disturbances that lead to an asymmetrical rotational movement of the shaft.

[0089] Within the scope of the present invention, "interaction with the calibration device according to the invention" means that the electric motor and / or the optical encoder comprise communication means to participate in data exchange with the calibration device according to the invention. Furthermore, the optical encoder comprises a correction unit according to the invention and / or non-volatile storage means.

[0090] In this context, it is particularly preferred if the alignment device uses communication means that are already included by the optical rotary encoder and are used in the subsequent application.

[0091] Furthermore, the electric motor and / or the optical rotary encoder is designed in such a way that the code disc can be measured by the second sensor means and in particular by the third and / or fourth sensor means at the respective angular positions in order to read the code track at the different angular positions and to generate the respective rotation angle signals.

[0092] Furthermore, the electric motor and / or the optical encoder is designed in such a way that a recess and / or a bore is provided for interaction with the positioning pin. The positioning pin thus enables fine positioning of the second and possibly further sensor elements relative to the code track and / or code disc. This advantageously reduces the signal quality and / or the error rate in the second rotary angle signal and possibly in further rotary angle signals.

[0093] Finally, it should be noted that to determine the calibration data, the shaft and / or the motor shaft must perform a rotational movement in order to generate at least the first and second rotation angle signals during the shaft's rotation. Preferably, the shaft rotation should complete at least one full revolution, which is then captured by at least the first and second rotation angle signals.

[0094] The calibration of the optical rotary encoder according to the invention further comprises the following steps: Fixing the code disk of the optical rotary encoder on a shaft; Adjusting the calibration device according to the invention from a rest state to a measuring state in order to bring the second sensor means - and any further sensor means - into operative contact with the code disk. Rotating the shaft for at least one full revolution, with the rotational movement being detected via the first sensor means and at least the second sensor means. Transmitting the first rotation angle signal from the optical rotary encoder to the adjustment device according to the invention via communication means. Calculation of the calibration data from the first rotation angle signal and at least the second rotation angle signal via an assignment rule using the computational means of the adjustment device. Transmitting the calculated calibration data from the adjustment device to the optical encoder; Adjusting the calibration device according to the invention from the measuring state to the resting state.

[0095] The invention is explained in more detail below by way of example with reference to the drawings. The combination of features shown as examples in the embodiments illustrated can be supplemented by further features according to the above explanations, in accordance with the properties of the invention necessary for a specific application. Likewise, individual features can be omitted in the described embodiments if their effect is not important in a specific application, also in accordance with the above explanations.

[0096] In the drawings, elements of the same function and / or structure are designated with the same reference symbol.

[0097] They show: Fig. 1a / b: a schematic representation of a balancing device according to the invention in a first preferred embodiment in a rest state and in a measuring state, each with an electric motor and an optical rotary encoder designed to interact with the balancing device; Fig. 2: a schematic representation of the adjustment device according to the invention in a second preferred embodiment and Fig. 3: a schematic representation of the code disc and several sensor devices.

[0098] The Fig. Figures 1a / b show in a highly schematic form the adjustment device 1 according to the invention for generating calibration data of an optical rotary encoder 100 in a rest state 21 of the adjustment device 1 (cf. Fig. 1a) and in a measurement state 20 of the adjustment device 1 (see Fig. 1b).

[0099] The optical rotary encoder 100, for which the calibration data are to be generated, comprises a code disk 101 mounted on a shaft 200 of an electric motor 300. The shaft 200 is rotatably mounted about a rotational axis R. The rotary encoder 100 also includes first sensor means 111 and a correction unit 112 (not shown in detail). The correction unit 112 is designed to generate a corrected rotational angle signal from the first rotational angle signal of the first sensor means 111 using the calibration data. Furthermore, the rotary encoder 100 includes non-volatile storage means 114 (not shown in detail) in which the calibration data can be stored non-volatilely and read out as needed.

[0100] The code disk 101 comprises an optical code track that can be read by the first sensor means 111 of the rotary encoder 100. The code disk 101 is mechanically coupled to the shaft 200. A change in the angle of the shaft 200 can be detected by the first sensor means 111. The first sensor means 111 thus generate a first rotational angle signal phi_1, which essentially represents the rotational movement of the shaft 200 at a first angular position α_1.

[0101] In the rotated top view of the optical turntable 101 in the assembled state, the first sensor means 111 are arranged at the first angular position α_1, which is defined here at 0° (see [reference]). Fig. 3).

[0102] The adjustment device 1 according to the invention also comprises second sensor means 2 which are set up in the measuring state 20 to interact with the code disk 101 at a second angular position α_2.

[0103] The second sensor means 2 read the code track of the code disk 101 to detect a change in the angle of the shaft 200 and generate a second rotational angle signal phi_2. The second rotational angle signal phi_2 represents the rotational movement of the shaft 200 at the second angular position α_2. The first angular position differs from the second angular position by essentially 180°. Thus, in measuring state 20, the second sensor means 2 are positioned at the second angular position α_2 via the handling means 5. This second position, in the rotated top view of the rotary disk 101, is at 180° and therefore opposite the first sensor means at α_1 = 0°.

[0104] The adjustment device 1 according to the invention also comprises handling means 5 according to the invention, wherein the second sensor means 2 are fixed to the handling means 5 according to the invention.

[0105] The handling means 5 are designed to adjust the position and / or the relative position between the second sensor means 2 and the code disk 101. By means of the handling means 5 according to the invention, the second sensor means 2 are moved from their rest state 21 by means of a translational adjustment movement along the vertical and thus along a Z-direction. Fig. 1a into measurement state 20 according to the Fig. 1b movable.

[0106] In measurement state 20, the second sensor means 2 are positioned relative to the code disk 101 in such a way that the second sensor means 2 read the code track encompassed by the code disk 101 at a second angular position α_2 in order to generate the second rotation angle signal phi_2 to map the rotational movement of the shaft 200 at the angular position α_2.

[0107] Furthermore, the calibration device 1 according to the invention comprises communication means 6 that enable data exchange between the calibration device 1 and the optical rotary encoder 100. The communication means 6 are configured such that at least the first rotation angle signal phi_1 and the generated calibration data can be exchanged between the calibration device 1 and the rotary encoder 100.

[0108] Finally, the adjustment device 1 according to the invention also includes computing means 7. The computing means 7 are arranged such that the calibration data for the optical encoder 100 can be determined from the first rotation angle signal phi_1, which was received by the communication means 6 from the optical encoder 100, and the second rotation angle signal phi_2 according to an assignment rule.

[0109] The code disc 101 is designed to reflect light rays. The code disc 101 comprises different areas. These areas can be divided into two groups: the first group exhibits good and / or high reflective properties, while the second group exhibits low reflective properties. Due to these varying degrees of reflective properties, a code track can be implemented in the code disc 101, which can be read by the two sensor elements 111 / 2.

[0110] Furthermore, the code disc 101 is designed such that the first sensor means 111 interact with the code disc 101 on its underside, and the second sensor means 2 of the alignment device 1 interact with the code disc 101 on its upper side. The upper side extends opposite the underside. The code disc can be coated on both sides. Alternatively, the code disc can be transparent, with only one side bearing the code track.

[0111] In other words, the code disc 101 according to the Fig. 1a / b is designed so that the code track can be read from both sides by the sensor means 111 / 2.

[0112] The Fig. Figure 2 shows another preferred embodiment of the calibration device according to the invention. Figure 1 in measurement state 20. The calibration device 1 again comprises the components already described in the exemplary embodiment according to the Fig. 1 known second sensor means 2 according to the invention, the handling means 5 according to the invention, the communication means 6 according to the invention and the computing means 7 according to the invention.

[0113] Furthermore, the adjustment device 1 includes a distance sensor 10. The distance sensor 10 is operatively connected to the handling means 5 in such a way that the distance between the second sensor means 2 and the code disc 101 can be monitored and selectively chosen and / or determined. Advantageously, this ensures that the second sensor means 2 are operatively connected to the code disc 101 in the measuring state 20. The distance sensor 10 generates a distance signal that can be evaluated by the handling means 5 in order to control the adjustment path in the Z-direction and thus to adjust the relative distance between the second sensor means 2 and the code disc 101 within predefinable tolerance limits.

[0114] Furthermore, the handling means 5 include a positioning pin 11. The positioning pin 11 extends along the Z-direction and is designed to interact with a centering sleeve and / or bore 102, which is encompassed by the optical rotary encoder 100. Advantageously, the relative position between the second sensor means 2 and the code disk 101 can be precisely determined via the positioning pin 11 with respect to an XY plane, wherein the XY plane extends transversely to the Z-direction.

[0115] The bore 102 for the fine positioning of the second sensor element 2 is located in the circuit board of the rotary encoder. Alternatively, for better accessibility, the bore can also be positioned in the bearing shield of the motor.

[0116] Furthermore, the handling means 5 are designed in this case as a support arm 12.

[0117] In the present embodiment, the support arm 12 is configured such that the second sensor means 2 are not only adjustable along the Z-direction to adjust the distance between the second sensor means 2 and the code disk within a tolerance range, but that the second sensor means 2 are also movable within the XY plane to position the second sensor means arbitrarily with respect to the radius and / or an extent dimension of the code disk 200. The illustrated adjustment device 1 according to the invention can thus be used when mounting different optical rotary encoders 101 and / or different electric motors 300 that differ with respect to the dimensions of the shaft 200 and / or the electric motor 300, and thus also differ with respect to the code disk 101 fixed on the shaft 200.

[0118] The Fig.Figure 3 shows a schematic representation of the code disk 101, mounted on a shaft 200, in a rotated top view. The code disk 101, together with the shaft 200, is mounted to rotate about the axis of rotation R and thus performs a relative movement to the sensor means 111 / 2 / 3 / 4.

[0119] The first sensor means 111 are mechanically and electrically fixed on a first circuit board 103 of the optical rotary encoder 100.

[0120] The second sensor means 2 are mechanically and electrically fixed on a circuit board 13 of the calibration device 1 according to the invention, wherein in the measurement state 20 shown in the figure, the second sensor means 2 are fixed at the second angular position α_2 and thus detect the relative movement of the code disk 101 at this position. In the present embodiment, α_2 corresponds essentially to 180°.

[0121] The third sensor means 3 are mechanically and electrically fixed on the same circuit board 13 of the calibration device 1 according to the invention, wherein in the measurement state 20 shown in the figure, the third sensor means 3 are fixed at the third angular position α_3 and thus detect the relative movement of the code disk 101 here. In this case, α_3 corresponds essentially to 90°.

[0122] The fourth sensor means 4 are also mechanically and electrically fixed on the circuit board 13 of the calibration device 1 according to the invention, wherein in the measurement state 20 shown in the figure, the fourth sensor means 4 are fixed at the fourth angular position α_4 and thus detect the relative movement of the code disk 101 here. In this case, α_4 corresponds essentially to 270°.

[0123] Furthermore, the rotated top view shows that all sensor means 111 / 2 / 3 / 4, in particular the first sensor means 111 on the one hand and the second sensor means 2, the third sensor means 3 and the fourth sensor means 4 on the other, each comprise light-generating means 8 for emitting light beams and light-detection means 9 for detecting light beams. The respective interacting pairs of light-generating means 8 and light-detection means 9 are arranged adjacent to each other on the respective circuit board 103 / 13 such that the light beams emitted by the light-generating means 8 are reflected back onto the respective light-detection means 9 when they strike a reflective area of ​​the code disk 101.

[0124] The code disc 101 comprises a code track formed from black and silver chrome areas, in order to generate a low proportion of reflected light rays with the black chrome area and a high proportion of reflected light rays with the silver chrome area.

Claims

[1] Calibration device (1) for generating calibration data for an optical rotary encoder (100), wherein the optical rotary encoder (100) comprises first sensor means (111), a code disk (101), a correction unit (112), and non-volatile storage means (114), wherein the code disk (101) is fixed on a rotatable shaft (200), and the first sensor means (111) are configured to interact with the code disk (101) at a first angular position (α_1) such that an angular change of the shaft (200) can be detected and a first rotational angle signal (phi_1) for mapping a rotational movement of the shaft (200) can be determined, and wherein the correction unit (112) is configured to correct the first rotational angle signal (phi_1) using the calibration data, comprising - second sensor means (2) which are arranged in a measuring state (20) of the adjustment device (1) to interact with the code disk (101) such that a second rotation angle signal (phi_2) can be determined; - Handling means (5) designed to adjust the relative position of the second sensor means (2) and / or the code disk (101) between the measuring state (20) and a rest state (21) such that in the measuring state (20) the second sensor means (2) interact with the code disk (101) at a second angular position (α_2) and that in the rest state (21) the second sensor means (2) are spaced away from the code disk (101) in such a way that they are not in operative connection, wherein the second angular position (α_2) of the second sensor means (2) differs from the first angular position (α_1) of the first sensor means (1); - Communication means (6) that enable data exchange between the alignment device (1) and the optical rotary encoder (100) such that at least the first rotation angle signal (phi_1) and the generated calibration data can be transmitted; - Computing means (7) which are designed such that the calibration data can be determined from the first rotation angle signal (phi_1) and the second rotation angle signal (phi_2) according to an assignment rule, characterized by , that the adjustment device (1) comprises a distance sensor (10), wherein the distance sensor (10) is designed such that a distance signal for mapping the distance between the second sensor means (2) and the code disk (101) can be generated and made available for the handling means (5). [2] Adjustment device according to claim 1, characterized by, that the second sensor means (2) comprise light-generating means (8) for emitting light rays and light-sensing means (9) for detecting light rays, in particular those reflected at the code disk (101). [3] Adjustment device according to claim 2, characterized by , that the light-generating means (8) and the light-sensing means (9) are positioned adjacent to and opposite the front of the code disk (101) at least in the measurement state (20) and / or that the code disc (101) is designed to reflect light rays and / or that the code disc (101) comprises a code track consisting of alternating weakly reflective, in particular black chrome areas, and strongly reflective, in particular silver-colored chrome areas, such that a small proportion of reflected light rays can be generated with one of the weakly reflective areas, in particular the black chrome areas, and a high proportion of reflected light rays can be generated with one of the strongly reflective areas, in particular the silver-colored chrome areas. [4] Adjustment device according to one of the aforementioned claims characterized by , that the handling means (5) are designed such that in the measuring state (20) the second angular position (α_2) and / or the position of the second sensor means (2) is selected such that the first sensor means (1) and the second sensor means (2) are positioned substantially rotated by 180° in a top view of the code disk (101). [5] Adjustment device according to one of the preceding claims characterized by , that the handling means (5) comprise third sensor means (3) and / or fourth sensor means (4), wherein the handling means (5) are configured such that, at least in the measurement state (20), the third sensor means (3) interact with the code disk (101) at a third angular position (α_3) and the fourth sensor means (4) interact with the code disk (101) at a fourth angular position (α_4), wherein, in top view, the first sensor means (1) are positioned substantially 90° away from the third sensor means (3) and the first sensor means (1) are positioned substantially 270° away from the fourth sensor means (4). [6] Adjustment device according to one of the aforementioned claims characterized by, that the adjustment device (1) comprises at least one positioning pin (11) which is designed to engage in a recess and / or bore (102) of the optical encoder (100), in particular in a recess of a circuit board of the optical encoder (100) and / or in a recess in a housing part of the electric motor (300) comprising the shaft (200), such that the relative position of the second sensor means (2) to the code disk (101), in particular with respect to an XY plane oriented transversely to the Z-axis, can be determined . [7] Adjustment device according to one of the aforementioned claims characterized by, that the handling means (5) are designed as a swivel and / or lifting arm (12) such that the relative distance of the second sensor means (2) and / or the third sensor means (3) and / or the fourth sensor means (4) to the axis of rotation (R) is adjustable in order to adapt the position of the second sensor means (2) and / or the third sensor means (3) and / or the fourth sensor means (4) to the dimensional dimension of the code disk (101). [8] Adjustment device according to one of the aforementioned claims characterized by , that the computational means (7) are designed such that the assignment rule processes the respective rotation angle signals (phi_1 / 2 / 3 / 4) depending on the respective angular positions (α_1 / 2 / 3 / 4) to determine the calibration data.

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