Magnetic rotary encoder and standby control method thereof

Abstract

Provided is a magnetic rotary encoder capable of generating rotation angle information with high precision by using an output signal of a second magnetic sensor, which is lower in precision than a first magnetic sensor and is inexpensive, as position information for standby control when the first magnetic sensor has failed. The present invention is provided with: a first magnetic sensor signal processing means for generating first analog data and first digital data relating to the rotation angle of a rotating shaft on the basis of the output of a first magnetic sensor; and a second magnetic sensor signal processing unit that generates second analog data and second digital data relating to the rotating shaft on the basis of AD conversion data output by a second magnetic sensor having a lower resolution than that of the first magnetic sensor, and generates second digital data relating to the rotating shaft on the basis of AD conversion data output by the second magnetic sensor. The output of the second magnetic sensor is corrected on the basis of the output of the first magnetic sensor as the fail-safe function of the rotary encoder, and the second analog data and the second digital data of the second magnetic sensor are corrected on the basis of the correction history of the second magnetic sensor as the fail-safe function of the rotary encoder.

Description

Technical Field

[0001] The present invention relates to a magnetic rotary encoder and a backup control method thereof, and relates to a magnetic rotary encoder having a backup function when a magnetic sensor or the like fails or when power is lost, and a backup control method thereof. Background Art

[0002] A rotary encoder is used to detect the angular position and rotational speed of a rotating shaft driven by a rotating motor. In particular, for a motor, such as a brushless DC motor, based on the angular position and rotational speed of the rotating shaft detected by a magnetic sensor, an absolute digital signal and an incremental digital signal related to the angular position are generated and output, and these signals are used to control the motor as a servo motor. In a rotary encoder used to control equipment such as an industrial robot where redundancy of the system is emphasized, in order to safely continue the operation of the equipment even when the rotary encoder fails during operation, a backup control function (fail-safe function) using other normal magnetic sensors is provided.

[0003] In the rotary angle detection device disclosed in Patent Document 1, the magnetic flux detection unit includes three or more rotary angle sensors using magnetic detection elements such as MR elements or Hall elements, and includes a rotary angle derivation unit that calculates the rotational angle of the output shaft based on the rotation of the rotary angle sensors other than the rotary angle sensor determined to be abnormal.

[0004] Patent Document 2 discloses the following invention: In a rotary angle detection device of a motor having a GMR sensor and an AMR sensor, normally, the output of the AMR sensor is corrected by the output of the GMR sensor to obtain the mechanical angle θ. When the GMR sensor fails, the mechanical angle θ is detected only by the output of the AMR sensor and backup control is performed. The microcomputer includes a counter. If it is determined based on the output of the GMR sensor that it is time to perform offset correction, the count value is recorded as 1 in the counter. When the GMR sensor fails, the output value of the AMR sensor is offset-corrected based on this count value.

[0005] The encoder disclosed in Patent Document 3 having an optical or magnetic angle detection unit includes a primary battery such as a battery, a button-type battery, or a dry battery, and a rechargeable secondary battery. Moreover, the following invention is disclosed: The secondary battery is charged by an electric signal generation unit using a magnetosensitive wire such as a Weigand wire, and at least a part of the rotational position information of the rotating shaft (for example, multi-rotation information) can be detected even in a state where the main power supply of the device equipped with the encoder device is not turned on (emergency state, standby state).

[0006] Prior Art Documents

[0007] Patent Document

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-164402

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2022-105702

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2016-109554 Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] In the invention of Patent Document 1, when it is determined that one rotation angle sensor of the rotation angle detection device is abnormal, the rotation angle of the output shaft can be calculated based only on the rotation of the other normal rotation angle sensors. Therefore, various industrial machines controlled by this rotation angle detection device have the advantage of being able to continue operating safely even if one rotation angle sensor becomes abnormal. On the other hand, in the invention of Patent Document 1, three or more rotation angle sensors need to use the same type of sensors with the same characteristics. When using high-precision rotation angle sensors, the overall cost may increase. Depending on the uses of various industrial machines, etc., there are also fields where backup control needs to be performed using cheaper and less-faulty rotation angle sensors.

[0013] In the invention of Patent Document 2, the GMR sensor and the AMR sensor are arranged at 180-degree intervals, so there is an offset between the output of the GMR sensor and the output of the AMR sensor. Therefore, when a failure occurs in the GMR sensor, based on this count value, the output value of the AMR sensor is corrected for offset. However, this offset is caused by a special structure in which the GMR sensor and the AMR sensor are arranged at 180-degree intervals. In addition, in Patent Document 2, there is no description of corrections other than the above-mentioned offset correction when a failure occurs in the GMR sensor.

[0014] In the invention of Patent Document 3, the power supply system includes a power switch (power selection unit, selection unit), which is configured to switch (select) which of the primary battery and the secondary battery charged by the electrical signal generation unit supplies power to the position detection system. However, when a failure occurs in the power switch, it may not be possible to properly supply power to the position detection system.

[0015] One problem of the present invention is to provide a magnetic rotary encoder and a backup control method thereof. During normal operation, high-precision rotation angle information is generated using the output signal of a first magnetic sensor. As position information for backup control in the case where the first magnetic sensor fails, the output signal of a second magnetic sensor with lower precision and lower cost than the first magnetic sensor is used, and high-precision rotation angle information can be generated.

[0016] Another problem of the present invention is to provide a magnetic rotary encoder having a backup control function, which can appropriately record the rotation angle information of the rotation shaft of a motor even during a power outage and appropriately provide the information required for the next motor startup.

[0017] Means for solving the problems

[0018] According to one aspect of the present invention, a rotary encoder includes:

[0019] A magnet fixed to a rotation shaft;

[0020] A processing unit for a first magnetic sensor signal that performs AD conversion on a first analog signal that is the output of a first magnetic sensor disposed opposite to the magnet, and generates first digital data based on the AD conversion data of the output of the first magnetic sensor. The first digital data is related to the rotation angle and rotation direction of the rotation shaft and includes information of two systems, an absolute signal and an incremental signal; and

[0021] A processing unit for a second magnetic sensor signal that performs AD conversion on a second analog signal that is the output of a second magnetic sensor disposed opposite to the magnet, and generates second digital data based on the AD conversion data of the output of the second magnetic sensor. The second digital data is related to the rotation angle and rotation direction of the rotation shaft and includes information of two systems, an absolute signal and an incremental signal,

[0022] The resolution of the second magnetic sensor is poorer than that of the first magnetic sensor,

[0023] The processing unit for the second magnetic sensor signal has a fail-safe function for backing up the processing unit for the first magnetic sensor signal,

[0024] The processing unit for the second magnetic sensor signal has the following functions:

[0025] Based on the data of the first analog signal of the first magnetic sensor, the second analog signal of the second magnetic sensor is corrected and the AD conversion is performed. Based on the first digital data of the first magnetic sensor, the AD conversion data of the output of the second magnetic sensor is corrected to generate the second digital data, and,

[0026] Record the correction history of the second analog signal and the correction history of the second digital data described above.

[0027] The fail-safe function of the rotary encoder is configured such that

[0028] when a failure occurs in the first magnetic sensor and / or the processing unit of the first magnetic sensor signal, correct the second analog signal of the second magnetic sensor based on the correction history of the second analog signal, and correct the second digital data of the second magnetic sensor based on the correction history of the second digital data.

[0029] According to one aspect of the present invention, a rotary encoder can be provided that uses a second magnetic sensor that is less accurate but less expensive than the first magnetic sensor to generate high-precision position information and can perform highly reliable backup control.

[0030] According to another aspect of the present invention, the first magnetic sensor is disposed on a printed circuit board at a position corresponding to the axis of the rotating shaft, the second magnetic sensors are arranged on the same surface of the printed circuit board as the first magnetic sensor and at 120-degree intervals on a circumference centered on the axis of the rotating shaft, and a temperature sensor is disposed on the printed circuit board.

[0031] The rotary encoder includes a main power supply, a Barkhausen effect power generation power supply, and a secondary battery as a power supply unit. The output voltages of the main power supply, the Barkhausen effect power generation power supply, and the secondary battery are controlled to a predetermined power. The Barkhausen effect power generation power supply and the secondary battery are power supplies for backup when the main power supply loses power. The Barkhausen effect power generation power supply includes a Barkhausen effect element, and the Barkhausen effect element is provided on the printed circuit board on the back side of the first magnetic sensor and generates electricity using the rotating magnetic field of the magnet. The secondary battery has a capacitor, and the capacitor is charged by the main power supply and the Barkhausen effect power generation power supply.

[0032] According to this aspect, a magnetic rotary encoder with a backup control function can be provided that can appropriately record information on the rotation angle of the motor's rotating shaft and appropriately provide the information required for the next motor startup even when a failure occurs in either the first magnetic sensor or the second magnetic sensor, and also during a power outage.

[0033] According to another aspect of the present invention, the first analog signal, the second analog signal, the first digital data, and the second digital data are monitored. When it is determined that there is an abnormality in the processing unit of the first magnetic sensor or the first magnetic sensor signal as a result of the monitoring of each piece of data, in the processing unit of the second magnetic sensor signal, a corrected analog signal based on the correction history of the second analog signal of the second magnetic sensor is generated, and the corrected second digital data is generated based on the corrected analog signal and the correction data of the second digital data.

[0034] According to this aspect, even when a failure occurs in the first magnetic sensor, highly reliable backup control can be performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a functional block diagram showing a configuration example of a rotary encoder according to a first embodiment of the present invention.

[0036] Figure 2 It is a diagram showing a configuration example of a servo control system including the rotary encoder of the first embodiment.

[0037] Figure 3 It is a longitudinal sectional view showing a configuration example of a magnetic sensor and a power supply unit in the rotary encoder of the first embodiment.

[0038] Figure 4 It is a diagram showing a configuration example of a circuit of the power supply unit in the first embodiment.

[0039] Figure 5 It is a timing chart showing the operation of the power supply unit, and is an example of a diagram showing the relationship between the power supply and the output signal of the rotary encoder when a power failure occurs in the main power supply from a normal state.

[0040] Figure 6 It is a diagram showing another configuration example of the circuit of the power supply unit.

[0041] Figure 7 It is a diagram showing the digitization and absolutization processing of the first magnetic sensor signal.

[0042] Figure 8 It is a flowchart showing signal processing in the processing unit of the first magnetic sensor signal in the first embodiment.

[0043] Figure 9 It is shown based on Figure 8 Examples of the A-phase and B-phase signals of the signal processing and the incremental Z-phase, U-phase, V-phase, and W-phase signals generated based on these signals.

[0044] Figure 10 This is a diagram showing the digital and absolute processing of the second magnetic sensor signal.

[0045] Figure 11 This is a flowchart showing the signal processing in the signal processing unit of the second magnetic sensor signal in the first embodiment.

[0046] Figure 12 This is a flowchart showing the processing of the fail-safe control unit in the first embodiment.

[0047] Figure 13 This is a flowchart showing the data processing of the signal processing unit of the second magnetic sensor signal during normal operation.

[0048] Figure 14 This is a flowchart showing the data processing of the signal processing unit of the second magnetic sensor signal in the fail-safe mode. Detailed implementation mode

[0049] Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings.

[0050] First, with reference to Figures 1 to 3 , the overall configuration and functions of the rotary encoder according to the first embodiment of the present invention will be described.

[0051] Figure 1 This is a functional block diagram showing a configuration example of the rotary encoder, Figure 2 This is a diagram showing a configuration example of the servo control system including the rotary encoder.

[0052] The rotary encoder 10 includes a magnetic sensor unit 11, a power supply unit 12, a temperature sensor 13, a system control unit 14, a processing unit 15 for the first magnetic sensor signal, and a processing unit 16 for the second magnetic sensor signal.

[0053] The rotary encoder 10 further includes a flat plate-shaped magnet 110 magnetized with one pole of N and S respectively. This flat plate-shaped magnet is, for example, a ferrite magnet, as Figure 3 shown, fixed to one end face of the rotary shaft 510 of the motor 50. It should be noted that rare earth magnets such as neodymium magnets and samarium cobalt magnets can also be used instead of ferrite magnets.

[0054] The magnetic sensor unit 11 includes a first magnetic sensor 111 and a second magnetic sensor 112, and the first magnetic sensor 111 has a temperature sensor 113.

[0055] The first magnetic sensor 111 is composed of a pair of magnetic sensors (Sin, Cos) and is arranged at a position facing the magnet 110 in the axial direction of the rotating shaft 510. That is, the first magnetic sensor 111 is arranged on the printed circuit board 17 at a position corresponding to the axis OO of the rotating shaft 510.

[0056] As the first magnetic sensor 111 used in the present invention, a sensor capable of obtaining high-precision resolution is used, and the second magnetic sensor is preferably a magnetic sensor that has a simple structure and is less prone to failure, although the resolution is lower than that of the first magnetic sensor.

[0057] In the first embodiment, a TMR sensor is used as the first magnetic sensor 111, and three Hall elements (H1, H2, H3) arranged at 120 degree intervals are used as the second magnetic sensor 112. The Hall element is made of GaAs, for example. It should be noted that the TMR sensor has a built-in temperature sensor, and its output is temperature compensated.

[0058] The power supply unit 12 includes a main power supply 121, a Barkhausen effect power generation power supply 122, and a sub-battery 123. The Barkhausen effect power generation power supply 122 and the sub-battery 123 function as power supplies for supplying power to the rotary encoder 10 when the power supply of the main power supply fails. A Barkhausen effect power generation unit 115 is provided near the magnet 110. The Barkhausen effect power generation unit 115 is fixed to a position on the printed circuit board 17 that becomes the back side of the first magnetic sensor 111 (see Figure 3 ). The Barkhausen effect power generation unit 115 has a composite magnetic wire and a coil. The composite magnetic wire is centered on the axis OO and is arranged in a direction orthogonal to the axis. The Barkhausen effect power generation unit 115 generates power based on the Barkhausen effect as the rotating shaft 510 rotates and as the magnetic flux Φb of the flat magnet 110 is generated, and its output is supplied to the Barkhausen effect power generation source 122.

[0059] The system control unit 14 has the following functions: as the output of the rotary encoder 10, when the first magnetic sensor 111 and the processing unit 15 for the first magnetic sensor signal function normally, the system control unit 14 outputs the information of the processing unit 15 for the first magnetic sensor signal; when an abnormality occurs in the first magnetic sensor 111 and the processing unit 15 for the first magnetic sensor signal, the system control unit 14 outputs the information of the processing unit 16 for the second magnetic sensor signal.

[0060] The initial setting unit 141 of the system control unit 14 has a setting unit 142 that sets the type of the motor, the number of poles, the origin of the rotation axis, the output conditions of the rotary encoder, etc. according to the conditions input via the user interface, and a holding function for the fail-safe control data 143. The fail-safe control data 143 includes, for example, data related to trigonometric functions used to correct the analog output of the second magnetic sensor based on the analog output of the first magnetic sensor for data correction, and data related to linear functions used to correct the digital output of the second magnetic sensor based on the digital output of the first magnetic sensor, etc.

[0061] The encoder input / output control unit 144 has a function of controlling the input / output of the rotary encoder 10 according to the initially set conditions. The fail-safe control unit 145 performs control of the fail-safe mode executed when a failure occurs in a magnetic sensor or the like. The output switching unit 146 has a function of switching the output of the rotary encoder according to the operating state of the rotary encoder. The serial / parallel signal transmission / reception unit 147 has a function of converting various information into parallel signals or serial signals and transmitting and receiving them between the rotary encoder 10 and the servo control device 40.

[0062] The rotary encoder 10 of the present invention can be applied to various rotary motors that require absolute data and incremental A, B, Z data.

[0063] Hereinafter, the configuration of applying the present invention to a rotary encoder for a brushless DC motor will be described in more detail.

[0064] The processing unit 15 for the first magnetic sensor signal performs AD conversion on the output, i.e., the first analog signal, of the first magnetic sensor disposed opposite to the magnet 110, and generates first digital data related to the rotation angle and rotation direction of the rotation axis based on the AD conversion data of the output of the first magnetic sensor. That is, the processing unit 15 for the first magnetic sensor signal has the following functions: regarding the rotation angle information of the rotation axis, it generates, with high precision, information of two systems, i.e., an absolute signal and an incremental signal with a high resolution (for example, 27 bits / rotation) obtained by quantifying the analog output of the first magnetic sensor 111 under predetermined conditions, as the first digital data. From the rotary encoder, as the first digital data, for example, the incremental A, B, Z, (U, V, W) signals are converted into transmission data (BUS) for serial transmission and sent to the servo control device via a communication cable.

[0065] In addition, a processing unit 16 of the second magnetic sensor signal performs AD conversion on the output of the second magnetic sensor disposed opposite to the magnet 110, i.e., the second analog signal, and generates second digital data related to the rotation angle and rotation direction of the rotation axis based on the AD conversion data of the output of the second magnetic sensor. That is, the processing unit 16 of the second magnetic sensor signal has the following functions: Regarding the rotation angle information of the rotation axis, it generates and outputs with high precision two systems of information, namely, an absolute signal and an incremental signal with a higher resolution (e.g., 21 bits / rotation), which are obtained by correcting the analog output of the second magnetic sensor 112 based on the correction history of the signal generated by the processing unit of the first magnetic sensor signal and quantifying it under a predetermined condition, as the second digital data.

[0066] The processing unit 15 of the first magnetic sensor signal includes an analog signal (sin, cos)-amplitude detection unit 151 as a processing unit for the first analog signal, an AD converter 152, and a digital signal processing unit 153.

[0067] The analog signal (sin, cos)-amplitude detection unit 151 receives the sampled data of the first analog signals (sin signal, cos signal) of the first magnetic sensor 111 as time series data, calculates the rotational speed, and temporarily records the rotation angle (mechanical angle) of these analog signals, the amplitude of the analog signals, the rotational speed Nx of the rotation axis, and the data of the temperature sensor 13 in the memory in association with each other. At the same time, the sampled data of the analog signals of the first magnetic sensor 111 is input to an AD converter 152 (ADC-1(sin)1521, ADC-2(cos)1522) of, for example, 64 bits and is converted into digital values, and these conversion values are recorded in the EEPROM-1(1523) as time series data.

[0068] The absolute signal generation unit 1532 of the first magnetic sensor of the digital signal processing unit 153 obtains the AD conversion data of the rotation axis from the EEPROM-1, generates an absolute signal of the rotation angle of the rotation axis, and records it in the EEPROM-2 as time series data.

[0069] In addition, the digital signal-frequency / rotation direction detection unit 1531 of the first magnetic sensor obtains digital values from the EEPROM-1, calculates its frequency, and records it in the EEPROM-2 together with the data of the rotation direction.

[0070] On the other hand, the incremental A, B, Z, (U, V, W) signal generation unit 1533 of the first magnetic sensor obtains the digital values of the absolute signal of the rotation angle of the rotation axis from the EEPROM-2 as the first digital data, generates incremental A, B, Z, (U, V, W) signals, and records them in the EEPROM-3 as time series data.

[0071] The processing unit 16 for the second magnetic sensor signal includes an analog signal processing section 160, an AD converter 162, and a digital signal processing section 163.

[0072] The distortion correction - amplitude - synchronization correction section 161 for the analog signal of the second magnetic sensor receives the sampled data of the second analog signals (sin signals of H1, sin signals of H2, sin signals of H3) of the second magnetic sensor 112 as time - series data, performs distortion correction corresponding to the eccentricity of each Hall element (H1, H2, H3) with respect to the axis O - O, calculates the rotational speed, and records it in the memory.

[0073] On the other hand, the rotation angle (mechanical angle) of the first analog signal of the first magnetic sensor 111, the amplitude of the analog signal, the rotational speed Nx, and the data of the temperature sensor 13 are obtained from the analog signal (sin, cos) - amplitude detection section 151 of the processing unit 15 for the first magnetic sensor signal. Then, these data are temporarily recorded in the memory in association with each other.

[0074] In addition, based on the rotation angle (mechanical angle) and amplitude of the first analog signal, the rotational speed Nx, and the data of the temperature sensor 13, amplitude correction and synchronization correction, that is, data correction, are performed on the data of the second analog signal of the second magnetic sensor 112 for each rotation. The corrected analog data and the correction history are recorded in the EEPROM - 4 (165).

[0075] It should be noted that for the second analog signal, amplitude correction and synchronization correction can also be performed separately for each signal corresponding to each Hall element (H1, H2, H3) with respect to the first analog signal. However, for high - speed processing, it is preferable to perform amplitude correction and synchronization correction together.

[0076] In addition, if an approximation formula of a trigonometric function associated with the data of the temperature sensor 13 is used in the correction of the data of the second analog signal, it is not necessary to perform data correction for each rotation of data, and data correction can be performed within a predetermined angular range, sampling unit, etc. That is, based on the data of the relationship between the preset approximation formula of the trigonometric function and the temperature sensor 13, and based on the data of the first analog signal of the first magnetic sensor 111 in the corresponding positional relationship, the data of the second analog signal at any rotation angle of the second magnetic sensor 112 can be directly corrected.

[0077] The corrected analog data is input to a 64 - bit AD converter 162 (ADC - 3 to 5 (1621 - 1623)) and converted into digital values, and these conversion values are recorded in the EEPROM - 5 (1624) as time - series data.

[0078] Fail-safe - In the "fail-safe mode" where the signal correction unit 164 detects a malfunction in the first magnetic sensor 111 or the processing unit 15 of the first magnetic sensor signal, based on the correction history recorded in the EEPROM-4 (165), the amplitude-synchronous correction of the second analog signal of the second magnetic sensor is performed, and the result is recorded in the EEPROM-4 (165) as the corrected analog data.

[0079] The absolute signal generation unit 1632 of the second magnetic sensor in the digital signal processing unit 163 obtains the AD-converted data for each rotation of the rotation axis from the EEPROM-5, generates an absolute signal of the rotation angle of the rotation axis, and records it in the memory as time-series (tentative) absolute data. This (tentative) absolute data is corrected in the digital signal detection - frequency / rotation direction correction unit 1631 of the second magnetic sensor. That is, the digital signal detection - frequency / rotation direction correction unit 1631 of the second magnetic sensor obtains the frequency / rotation direction data of the digital signal of the first magnetic sensor for each rotation generated by the digital signal - frequency / rotation direction detection unit 1531 of the first magnetic sensor, performs the synchronization - rotation direction correction of the time-series absolute data of the second magnetic sensor, and records the result in the EEPROM-7 as the second digital data, that is, the (formal) absolute data of the second magnetic sensor. In addition, the correction history of the absolute data is recorded in the EEPROM-6 (166).

[0080] It should be noted that if an approximate formula of a linear function is used in the data correction, it is not necessary to correct the data based on the data for each rotation, and the data can be corrected within a predetermined angular range. That is, based on the pre-set approximate formula of the linear function and the data of the temperature sensor 13, and based on the first digital data of the first magnetic sensor 111 in the corresponding positional relationship, the second digital data at any rotation angle of the second magnetic sensor 112 can be corrected.

[0081] On the other hand, the incremental A, B, Z, (U, V, W) signal generation unit 1633 of the second magnetic sensor obtains the digital value of the absolute signal of the rotation angle of the corrected rotation axis from the EEPROM-7, generates incremental A, B, Z, (U, V, W) signals, and records them in the EEPROM-8 as time-series data.

[0082] In the "fail-safe mode", based on the correction history of the absolute data recorded in the EEPROM-6, the frequency / rotation direction correction of the absolute data of the second magnetic sensor is performed on the AD-converted data for each rotation of the rotation axis obtained from the EEPROM-5, and the result is recorded in the EEPROM-6 as the corrected digital value - correction history.

[0083] It should be noted that Figure 1 The functional modules shown are presented as an example. The distinction between the functional modules is arbitrary. Of course, the above-mentioned multiple functional modules can also be implemented through a shared program, or a specific above-mentioned functional module can be implemented through multiple different programs and IC circuits.

[0084] Alternatively, by installing a program for executing the above-mentioned various functions in a microcomputer equipped with a CPU and a memory, the above-mentioned various functions can also be realized.

[0085] As Figure 2 shown, the rotary encoder 10, together with the servo control device 40 and the motor 50, constitutes a servo control system.

[0086] Most of the rotary encoder 10, that is, the part of the magnetic sensor unit 11 except for the flat magnet 110, the power supply unit 12, the temperature sensor 13, the system control unit 14, the processing unit 15 for the first magnetic sensor signal, and the processing unit 16 for the second magnetic sensor signal are formed or mounted on the printed circuit board 17. This printed circuit board is fixed to the housing of the motor 50 (not shown).

[0087] In particular, the system control unit 14, the processing unit 15 for the first magnetic sensor signal, and the processing unit 16 for the second magnetic sensor signal are implemented as a dedicated FPGA 18 (Field Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit), or as a chip of an IC circuit using a general single-chip microcomputer, and are formed on the printed circuit board 17.

[0088] It should be noted that the system control unit 14, the processing unit 15 for the first magnetic sensor signal, and the processing unit 16 for the second magnetic sensor signal are functionally divided modules, and these functions are realized through the description of programs in digital signal processing units, SSC interfaces, incremental interfaces, etc. of FPGA and ASIC.

[0089] It should be noted that the FPGA includes a ROM, a RAM, and at least one rewritable (erasable) non-volatile memory, and is connected to the CPU via a bus. In addition, as the rewritable (erasable) non-volatile memory, EEPROM, FRAM (Ferroelectric Random Access Memory (registered trademark)), etc. can be used. In the following description, such a memory will be simply referred to as EEPROM.

[0090] A pair of magnetoresistive effect elements constituting the first magnetic sensor 111 are arranged at a predetermined interval in the rotational direction of the rotating shaft such that the phases of the output analog signals are shifted from each other by 90 degrees. As the first magnetic sensor 111, TMR (Tunnel magnetoresistance effect) elements are used. The first magnetic sensor 111 senses the magnetic flux Φa of the plate-shaped magnet 110 as the rotating shaft 510 rotates and outputs sine waves and cosine waves.

[0091] It should be noted that the position of one end on the boundary line between the N-pole region and the S-pole region of the magnet 110 is a specific position in the circumferential direction on the rotating shaft, that is, the origin position (Z0) corresponding to the rising time point of the pulse of phase A.

[0092] The three Hall elements of the second magnetic sensor 112 are arranged at equal intervals outside the first magnetic sensor 111 in the radial direction on the printed circuit board 17. A Hall IC may be used instead of the Hall element. Hereinafter, the Hall element or the Hall IC will be simply referred to as the "Hall element".

[0093] Next, with reference to Figure 4 A configuration example of the circuit of the power supply unit in the first embodiment will be described.

[0094] The main power supply 121 of the power supply unit 12 includes, for example, a main power supply section 1211 that converts the power supplied from a commercial power supply into a DC power supply and controls it to a predetermined DC voltage Vcc, for example, 5V. The main power supply section 1211 supplies power to the output terminal 124 via the diode 1221.

[0095] The Barkhausen effect power generation power supply 122 outputs, at intervals of 180 degrees, positive and negative pulsed waveforms from the Barkhausen effect power generation unit 115 every time the rotating shaft makes one revolution. The power is supplied to the output terminal 124 via the full-wave waveform circuit 1222, the smoothing circuit 1223, and the diode 1231 as DC power of a predetermined voltage Vcc.

[0096] The auxiliary battery 123 includes a current limiting circuit 1232, a capacitor 1233, and a voltage limiting circuit 1234, and supplies DC power with a predetermined voltage Vcc to the output terminal 124. The capacitor 1233 is independently powered by both the main power supply 121 and the Barkhausen effect power generation power supply 122. The capacitor 1233 functions as a power supply for supplying power to the rotary encoder 10 in a state where the main power supply has lost power and the rotating shaft has also stopped rotating. The current limiting circuit 1232 controls such that when the rotational speed of the motor is high and the amount of power generated by the Barkhausen effect power generation unit 115 is large, by limiting the current supplied to the capacitor 1233, charges within the allowable range are stored in the capacitor 1233. The capacitor 1233 may, for example, be an electric double layer capacitor. In order to make the voltage reduction gentle, the capacitor 1233 may be constituted by connecting a plurality of capacitors in parallel.

[0097] The power supply lines connected to the output terminal 124 of the power supply unit 12 are configured as three electrically independent systems of lines, and supply power to each of the system control unit 14, the processing unit 15 for the first magnetic sensor signal, the processing unit 16 for the second magnetic sensor signal, and the sensors of the magnetic sensor unit 11.

[0098] Figure 5 It is a timing chart showing the operation of the power supply unit, and is a diagram showing an example of the relationship between the power supply and the output signal of the rotary encoder when the main power supply of the main power supply is powered off from a normal state.

[0099] When the main power supply unit 1211 of the main power supply cannot supply power at time t1 due to, for example, a power outage or a failure, power is supplied to the rotary encoder 10 from the Barkhausen effect power generation power supply 122 that generates electricity along with the rotation of the rotating shaft.

[0100] After the power outage, as time passes and the rotational speed of the rotating shaft decreases, the output of the Barkhausen effect power generation becomes smaller, and at time t2, DC power with a predetermined voltage Vcc cannot be supplied. When this state is reached, power with voltage Vcc is supplied to the rotary encoder 10 by the charge stored in the capacitor 1233 of the auxiliary battery 123.

[0101] Thereby, the rotary encoder 10 can generate and record information on the rotation angle of the rotating shaft for a long time, for example, until time t3 when the rotation of the rotating shaft completely stops.

[0102] In addition, after the rotation axis stops due to a power outage, in the case where the rotation axis is forcibly rotated via the robotic arm by an external force (e.g., manual force), the output generated by power generation through the Barkhausen effect and the charge stored in the capacitor 1233 supply power to the rotation encoder 10 during the time period from t4 to t5. Therefore, even in the state where the rotation axis rotates due to an external force after stopping due to a power outage, the information on the rotation angle of the rotation axis is recorded.

[0103] Next, Figure 6 is a diagram showing another configuration example of the circuit of the power supply unit. The MOSFET 1236 controlled by the PWM control unit 1235 is adopted instead of Figure 4 the current limiting circuit 1232, and PWM control is performed on the current supplied from the Barkhausen effect power generation unit 115 to the capacitor 1233. The reference numeral 1237 is a resistor for current detection. The capacitor 1233 is powered separately from both the main power supply 121 and the Barkhausen effect power generation power supply 122. In this example, PWM control of the MOSFET 1236 is performed based on the detected values of the charging voltage and current of the capacitor 1233 so as to control the charge stored in the capacitor 1233 to an optimal value.

[0104] In this example, the rotation encoder 10 can also generate and record the information on the rotation angle of the rotation axis for a long time, for example, until the rotation of the rotation axis stops, or until the external force drives it later.

[0105] Next, with reference to Figure 7 、 Figure 8 、 Figure 9 ,the digitalization and absolutization processing of the first magnetic sensor signal in the first magnetic sensor signal processing unit 15 will be described.

[0106] The first magnetic sensor signal processing unit 15 obtains information on the number of poles of the motor and the origin of the rotation axis from the initial set value (S701).

[0107] As shown in (A) of Figure 7 , from the first magnetic sensor (TMR sensor) 111, corresponding to one rotation of the rotation axis, first analog signals of 360 degrees (mechanical angle) each for the SIN wave and the COS wave and one cycle each are output. The data on the rotation angle (mechanical angle), amplitude, and rotational speed Nx of these first analog signals are recorded in the memory in association with the temperature Ta of the temperature sensor 13 by the analog signal (sin, cos)-amplitude detection unit 151 of the first magnetic sensor signal processing unit 15. Generally, since the Hall element is more susceptible to the ambient temperature than the TMR sensor, such processing is required.

[0108] Here, assuming that the first analog signal output from the first magnetic sensor (TMR sensor) is an exact sine wave, if the displacement y1 (i.e., amplitude) at time t and position x is set as y1(x, t), then y1(x, t) is represented by the following equation.

[0109] y1(x,t)=Asin2π(t / T - x / λ) (1)

[0110] Where T is the period, λ is the wavelength, and A is a constant.

[0111] The actual analog signal output from the first magnetic sensor is temperature-compensated and can be considered as a signal approximated to the above equation (1).

[0112] Therefore, it is possible to pre-obtain the approximate expressions of the trigonometric functions of the SIN wave and COS wave representing the actual analog signal output from the first magnetic sensor in relation to the temperature Ta of the substrate, y1(x, t, Ta), and store them as initial setting data. Using the approximate expressions of these trigonometric functions, it is possible to generate data on the rotation angle (mechanical angle), amplitude, and rotational speed Nx of the above first analog signal. Thus, it is possible to generate correction data for the second analog signal with high precision over a wide range from the low-speed rotation region to the high-speed rotation region.

[0113] As Figure 7 shown in (B) of , the analog signals (sin signal, cos signal) are input to the AD converter 152, quantized, and converted into a multi-segmented digital signal through interpolation processing, and converted into digital values containing the information of phase A and phase B. These conversion values are recorded in the EEPROM-1 in association with the rotational speed Nx and the temperature Ta.

[0114] As Figure 8 shown in the flowchart of , the processing unit 15 of the first magnetic sensor signal acquires the AD-converted data (S702) of the first magnetic sensor signal (Sin, Cos waves) from the EEPROM-1. The processing unit 15 of the first magnetic sensor signal further interpolates the digital waveform as needed by time division or the like based on the AD-converted data of the first analog signal (sin signal, cos signal), and changes it into data of, for example, a 27-bit rotation angle representing the absolute position from the origin, and calculates it as an absolute value (S703). Then, an address of the memory is added to the absolute value and recorded in the memory (S704).

[0115] That is, as Figure 7As shown in (C), through the digital signal - frequency / rotation direction detection unit 1531 of the first magnetic sensor, based on the digital value of EEPROM - 1, the frequency of each forward and reverse rotation of the rotating shaft is calculated, the absolute value of each forward and reverse rotation is generated, and it is recorded in EEPROM - 2 together with the data of the rotational speed Nx, temperature Ta, and rotation direction.

[0116] Here, assuming that the first analog signal output from the first magnetic sensor is an exact sine wave, if the absolute value obtained based on the digital value of EEPROM - 1 is set as y2(x, t), then y2(x, t) can be represented by a linear function related to the temperature Ta.

[0117] That is, the Figure 7 absolute value as shown in (C) based on the actual analog signal output from the first magnetic sensor can also be approximated by the above linear function. Therefore, according to the temperature Ta, the approximation formulas of the absolute values of the SIN wave and COS wave based on the actual analog signal output from the first magnetic sensor can be obtained in advance and stored as initial setting data. Using the approximation formulas of the absolute values, the absolute value of each forward and reverse rotation can be generated. Thus, calibration data of high - precision absolute data can be generated in a wide range from the low - speed rotation region to the high - speed rotation region.

[0118] In addition, in the digital signal - frequency / rotation direction detection unit 1531 of the first magnetic sensor, multi - rotation information including the rotation direction, rotation angle, and rotational speed is generated based on the origin information and the absolute value and recorded in EEPROM - 2 (S711).

[0119] The absolute signal generation unit 1532 of the first magnetic sensor calculates the rotational speed based on the origin information and the absolute value (S721), generates multi - rotation absolute information, and records it as multi - rotation absolute data in EEPROM - 2 (S722).

[0120] In addition, the incremental A, B, Z, (U, V, W) signal generation unit 1533 of the first magnetic sensor, based on the AD - conversion data and the absolute value, calculates the data of the A - phase and B - phase based on Figure 7 the information of the A - phase and B - phase shown in (B), calculates the data of the width of the Z - phase synchronized with the rising edges of the A - phase and B - phase (S731). In addition, based on the data of the widths of the A - phase, B - phase, and Z - phase, Figure 9 the data of the U, V, W phases as shown is generated (S733), and addresses are added to the data of the A - phase, B - phase, Z - phase, U, V, W phases, and they are recorded as incremental data in EEPROM - 3 (S734).

[0121] Next, refer to Figure 10 and Figure 11, the signal processing in the signal processing unit for the second magnetic sensor signal in the first embodiment will be described.

[0122] From each Hall element H1 to H3 constituting the second magnetic sensor, a sin signal (H1 to H3), the sin signal of H2, and the sin signal of H3) waveform that rises or falls every 180 degrees during one rotation as shown by the solid line in (A) of Figure 10 is obtained as the second analog signal. This waveform shows the data after distortion correction based on the installation position. Variations caused by errors in the positions of the Hall elements as the second magnetic sensor, deviations in the characteristics of the elements, ambient temperature, etc. are relatively large. Figure 10 The dashed line shown in (A) of

[0123] The data of the analog output of the Hall element is recorded in the memory in association with the data of the rotational speed Nx and the temperature Ta. Regarding the data of the analog output of the Hall element associated with the temperature Ta, it can also be expressed by an approximate formula in the same way as the above formula (1).

[0124] Then, the rotation angle (mechanical angle), amplitude, rotational speed Nx, and data of the temperature sensor 13 of the analog signal of the first magnetic sensor 111 are obtained from the first analog signal (sin, cos)-amplitude detection unit 151 of the first magnetic sensor signal processing unit 15. Then, based on the rotation angle (mechanical angle) and amplitude of the first analog signal, the data of the rotational speed Nx, and the temperature Ta of the temperature sensor 13, the data of the second analog signal of the second magnetic sensor 112 for each rotation is subjected to amplitude correction, synchronization correction, that is, data correction. The corrected analog data is recorded in the EEPROM-4 (165) in association with the data of the rotational speed Nx and the temperature Ta, together with the correction history. Figure 10 (B) of

[0125] As described above, the correction history can also express the corrected analog data y2 by the approximate formula y2(x, t, Ta) of the trigonometric functions representing the SIN wave and COS wave of the first analog signal.

[0126] The corrected analog data is input to the AD converter 162 (ADC-3 to 5) and converted into digital values, and these conversion values are recorded in the EEPROM-5 as time series data.

[0127] Figure 10 (C) of

[0128] Figure 10 (D) shows an example of the (provisional) absolute value based on the output of the second magnetic sensor signal. The (provisional) absolute value shown by the solid line includes phase errors and the like that depend on the characteristics of the second magnetic sensor. (It should be noted that, for ease of understanding, the errors are described in an exaggerated manner). In particular, it is envisioned that digital conversion is performed in a state where errors caused by the influence of the temperature Ta in the stage where the second analog signal cannot be sufficiently eliminated. Figure 10 The dashed line shown in (D) shows the absolute value based on the output of the corresponding first magnetic sensor.

[0129] In the digital signal detection - frequency / rotation direction correction unit 1631 of the second magnetic sensor signal processing unit 16, based on the origin information and the absolute value, multi - rotation information including the rotation direction, rotation angle, and rotational speed is generated and recorded in the EEPROM - 7 ( Figure 11 of S911).

[0130] That is, the digital signal detection - frequency / rotation direction correction unit 1631 of the second magnetic sensor acquires the frequency / rotation direction data of the digital signal of the first magnetic sensor per rotation generated by the digital signal - frequency / rotation direction detection unit 1531 of the first magnetic sensor, synchronizes the time - series (provisional) absolute data of the second magnetic sensor, corrects the rotation direction, and records the result as the (official) absolute data of the second magnetic sensor in the EEPROM - 7. In addition, the correction history of the absolute data is recorded in the EEPROM - 6.

[0131] Figure 10 (E) shows an example of the (official) absolute value based on the output of the second magnetic sensor signal. As described above, Figure 10 the absolute value in (E) can also be approximated by a linear function.

[0132] In Figure 11 , the second magnetic sensor signal processing unit 16 acquires information on the number of poles of the motor and the origin of the rotation axis from the initial set value (S901). It is also possible to acquire the approximate formula of the trigonometric function and the data of the linear function for data correction from the initial set value.

[0133] Next, the second magnetic sensor signal processing unit 16 acquires the AD - converted data of the second magnetic sensor signal (Sin wave) that has been corrected from the EEPROM - 6 (S902). In addition, based on the AD - converted data, the digital waveform is interpolated by time - division or the like as needed, and converted into, for example, 23 - bit rotation angle data representing the absolute position from the origin, and the (provisional) absolute value is calculated (S903). Then, the memory address is added to this (provisional) absolute value and recorded in the memory (S904).

[0134] The absolute signal generation unit 1632 of the second magnetic sensor of the digital signal processing unit 163 calculates the rotational speed (S921) based on the origin information and the absolute value, generates multi-rotation absolute information, and records it as multi-rotation absolute data in the EEPROM-7 (S922).

[0135] The incremental A, B, Z, (U, V, W) signal generation unit 1633 of the second magnetic sensor of the digital signal processing unit 163 calculates the data of the A-phase and B-phase based on the AD conversion data and the absolute value (S931), calculates the data of the width of the Z-phase synchronized with the rising edges of the A-phase and B-phase (S932), generates the data of the U, V, W phases based on the data of the widths of the A-phase, B-phase, and Z-phase (S933), attaches addresses to the data of the A-phase, B-phase, Z-phase, U, V, W phases, and records it as incremental data in the EEPROM-8 (S934).

[0136] Next, refer to Figure 12 The processing of the fail-safe control unit 145 in the first embodiment will be described.

[0137] First, information related to the normal determination of the data in the EEPEOM1 to EEPEOM3 and EEPEOM4 to EEPEOM8 is obtained from the initial setting unit (S1001). Next, the data for each rotation of the EEPEOM1 to EEPEOM3 is monitored (S1002). In addition, the data for each rotation of the EEPEOM4 to EEPEOM8 is monitored (S1003). It should be noted that the monitoring of the data may not be performed for each rotation. For example, it may be performed at a predetermined time period.

[0138] Next, it is determined whether all data is normal (S1004). If it is normal, normal operation is performed (S1005), and it is continued until the operation ends (S1006, S1007). If it is determined in S1004 that not all data is normal, then it is determined whether the data of EEPEOM1 to EEPEOM3 is normal (S1010). If it is normal, an abnormality display of the second magnetic sensor or the processing unit of the second magnetic sensor signal is performed (S1011), and quasi-normal operation is performed using the data of EEPEOM1 to EEPEOM3 (S1012), and it is continued until the operation ends (S1013, S1014). If it is determined in S1010 that the data of EEPEOM1 to EEPEOM3 is not normal, then it is determined whether the data of EEPEOM4 to EEPEOM8 is normal (S1020). If it is normal, an abnormality display of the first magnetic sensor or the processing unit of the first magnetic sensor signal is performed (S1021), and fail-safe mode operation is performed using the data of EEPEOM4 to EEPEOM8 (S1022), and it is continued until the operation ends (S1023, S1024). If it is determined in S1020 that the data of EEPEOM4 to EEPEOM8 is not normal, then an encoder error display is performed (S1030), and operation end processing is performed (S1031, S1032).

[0139] Next, with reference to Figure 13 , the data processing (S1101) of the processing unit of the second magnetic sensor signal during the normal operation of the rotary encoder will be described.

[0140] The processing unit of the second magnetic sensor signal acquires the number of poles of the motor and the information of the origin of the rotating shaft from the initial setting value of the data processing of the second magnetic sensor during normal operation (S1012). Then, it acquires the data of the second analog signal of the second magnetic sensor and performs distortion correction processing (S1103). In addition, it acquires the data of the first analog signal of the first magnetic sensor that is in a synchronous relationship with the signal of the second magnetic sensor (S1104).

[0141] Next, based on the amplitude of the data of the first analog signal of the corresponding first magnetic sensor, the amplitude of the data of the second analog signal of the second magnetic sensor is corrected (S1105). Then, the corrected analog signal data of the second magnetic sensor is recorded in EEPROM-4 (S1106). In addition, the analog signal correction history is recorded in EEPROM-4 (S1107). Next, the corrected analog signal data is AD-converted using the AD converter 162, and the second digital data is recorded in EEPROM-5 (S1108).

[0142] Next, obtain the second digital data of the second magnetic sensor from the EEPROM-5 (S1109), and correct the rotation angle and rotation direction of the second digital data of the second magnetic sensor based on the rotation angle and rotation direction of the first digital data of the corresponding first magnetic sensor (S1110). Then, record the corrected digital data of the second magnetic sensor in the EEPROM-6 (S1111). In addition, record the correction history of the second digital data in the EEPROM-6 (S1112). Repeat the above process until the operation ends.

[0143] Next, refer to Figure 14 , and describe the data processing (S1201) of the second magnetic sensor signal in the fail-safe mode of the rotary encoder.

[0144] First, obtain the number of poles of the motor, the information of the origin of the rotating shaft, and the fail-safe control data from the initial setting value (S1202). Next, obtain the data of the second analog signal of the second magnetic sensor (S1203). In addition, obtain the correction history data of the analog signal from the EEPROM-4 (S1204). Then, correct the distortion-amplitude of the data of the second analog signal of the second magnetic sensor based on the fail-safe control data and the correction history of the analog signal (S1205). In addition, record the corrected analog signal data of the second magnetic sensor in the EEPROM-4 (S1206). In addition, perform AD conversion on the corrected analog signal data using the AD converter 162, and record the second digital data in the EEPROM-5 (S1207).

[0145] Next, obtain the second digital data of the second magnetic sensor from the EEPROM-5 (S1208). On the other hand, obtain the data of the digital data correction history from the EEPROM-6 (S1209). Then, correct the rotation angle and rotation direction of the second digital data of the second magnetic sensor based on the fail-safe control data and each data of the (digital data) correction history (S1210). In addition, record the corrected digital data of the second magnetic sensor in the EEPROM-6 (S1211). Repeat the above process until the operation ends.

[0146] According to an embodiment of the present invention, the second digital data of the second magnetic sensor is corrected based on the first digital data of the first magnetic sensor, and based on these correction histories, the second digital data of the second magnetic sensor can be corrected during standby control. Therefore, a rotary encoder that uses a second magnetic sensor that is inexpensive but has low accuracy and can perform highly reliable standby control can be provided.

[0147] It should be noted that, as an embodiment of the present invention, as the second magnetic sensor, an AMR (Anisotropic magnetoresistance effect) element can also be used instead of the Hall element. Alternatively, a GMR (Giant magnetoresistance effect) element can also be used. These AMR sensors and GMR sensors are also arranged at equal intervals on a circumference centered on the first magnetic sensor, in the same manner as the example of the Hall element.

[0148] The present invention can also be applied to other types of motors, such as stepping motors. In addition, it can be widely applied to various motors such as synchronous motors and induction motors. In addition, the present invention can also be applied to a servo control device using these motors.

[0149] Description of reference numerals

[0150] 10: Rotary encoder;

[0151] 11: Magnetic sensor unit;

[0152] 110: Magnet;

[0153] 111: First magnetic sensor;

[0154] 112: Second magnetic sensor;

[0155] 113: Temperature sensor;

[0156] 12: Power supply unit;

[0157] 121: Main power supply;

[0158] 122: Barkhausen effect power generation power supply;

[0159] 123: Secondary battery;

[0160] 13: Temperature sensor;

[0161] 130: Encoder output control unit;

[0162] 14: System control unit;

[0163] 142: Setting unit;

[0164] 143: Data for fail-safe control;

[0165] 144: Encoder input / output control unit;

[0166] 145: Fail-safe control unit;

[0167] 146: Output switching unit;

[0168] 147: Serial / Parallel Signal Transmitting and Receiving Unit;

[0169] 15: Processing Unit for the First Magnetic Sensor Signal;

[0170] 151: Analog Signal (sin, cos)-Amplitude Detection Section for the First Magnetic Sensor;

[0171] 152: AD Converter;

[0172] 1521: ADC-1 (sin);

[0173] 1522: ADC-2 (cos);

[0174] 1523: EEPROM-1;

[0175] 153: Digital Signal Processing Section;

[0176] 1531: Digital Signal-Frequency / Rotation Direction Detection Section for the First Magnetic Sensor;

[0177] 1532: Absolute Signal Generation Unit for the First Magnetic Sensor;

[0178] 1533: Incremental A, B, Z, (U, V, W) Signal Generation Unit for the First Magnetic Sensor;

[0179] 16: Processing Unit for the Second Magnetic Sensor Signal;

[0180] 160: Analog Signal Processing Section;

[0181] 161: Distortion Correction-Amplitude-Synchronization Correction Section for the Analog Signal of the Second Magnetic Sensor;

[0182] 162: AD Converter;

[0183] 163: Digital Signal Processing Section;

[0184] 1631: Digital Signal Detection-Frequency / Rotation Direction Correction Section for the Second Magnetic Sensor;

[0185] 1632: Absolute Signal Generation Unit for the Second Magnetic Sensor;

[0186] 1633: Incremental A, B, Z, (U, V, W) Signal Generation Unit for the Second Magnetic Sensor;

[0187] 164: Fail-Safe-Signal Correction Section;

[0188] 17: Printed Circuit Board;

[0189] 18: FPGA;

[0190] 40: Servo control device;

[0191] 50: Motor;

[0192] 510: Rotating shaft;

[0193] H1, H2, H3: Hall elements.

Claims

1. A rotary encoder, comprising: A magnet fixed to a rotating shaft; A processing unit for a first magnetic sensor signal, which performs AD conversion on a first analog signal that is the output of a first magnetic sensor arranged opposite to the magnet, and generates first digital data based on the AD conversion data of the output of the first magnetic sensor. The first digital data is related to the rotation angle and rotation direction of the rotating shaft and includes information of two systems, namely an absolute signal and an incremental signal; and A processing unit for a second magnetic sensor signal, which performs AD conversion on a second analog signal that is the output of a second magnetic sensor arranged opposite to the magnet, and generates second digital data based on the AD conversion data of the output of the second magnetic sensor. The second digital data is related to the rotation angle and rotation direction of the rotating shaft and includes information of two systems, namely an absolute signal and an incremental signal, Characterized in that, The resolution of the second magnetic sensor is poorer than that of the first magnetic sensor, The processing unit for the second magnetic sensor signal has a fail-safe function for backing up the processing unit for the first magnetic sensor signal, The processing unit for the second magnetic sensor signal has the following functions: Based on the data of the first analog signal of the first magnetic sensor, the second analog signal of the second magnetic sensor is corrected and the AD conversion is performed. Based on the first digital data of the first magnetic sensor, the AD conversion data of the output of the second magnetic sensor is corrected to generate the second digital data, and The correction history of the second analog signal and the correction history of the second digital data are recorded, The fail-safe function of the rotary encoder is configured such that, When a failure occurs in the first magnetic sensor and / or the processing unit for the first magnetic sensor signal, based on the correction history of the second analog signal, the second analog signal of the second magnetic sensor is corrected, and based on the correction history of the second digital data, the second digital data of the second magnetic sensor is corrected.

2. The rotary encoder according to claim 1, characterized in that, The first magnetic sensor is arranged on a printed circuit board at a position corresponding to the axis core of the rotating shaft, The second magnetic sensor is arranged on the same surface of the printed circuit board as the first magnetic sensor and at intervals of 120 degrees on a circumference centered on the axis core of the rotating shaft, A temperature sensor is arranged on the printed circuit board.

3. The rotary encoder according to claim 2, characterized in that, The processing unit for the first magnetic sensor signal has the following functions: performing AD conversion on the data of the first analog signal of the first magnetic sensor and recording it, and temporarily recording the rotation angle (mechanical angle) and amplitude of the first analog signal, the rotational speed Nx, and the data of the temperature sensor in a memory as correction data for the second analog signal in an associated manner, The processing unit for the second magnetic sensor signal has the following functions: for the second analog signal of the second magnetic sensor, based on the amplitude, rotational speed Nx, the data of the temperature sensor, and the calibration data of the first magnetic sensor, it generates calibrated analog data and records the calibration history of the calibrated analog data for use in the fail-safe function.

4. The rotary encoder according to claim 2, wherein The processing unit for the first magnetic sensor signal has the following functions: it detects and records the frequency and the rotational direction of the first digital data of the first magnetic sensor, and temporarily records the rotational angle (mechanical angle), amplitude, rotational speed Nx, and the data of the temperature sensor of the first digital data as calibration data for the second digital data in a memory in an associated manner. The processing unit for the second magnetic sensor signal has the following functions: based on the calibration history of the second digital data, it calibrates and records the second digital data of the second magnetic sensor, and records the calibration history of the calibrated second digital data for use in the fail-safe function.

5. The rotary encoder according to claim 2, wherein The magnet fixed to the rotary shaft is a flat magnet. The first magnetic sensor is a pair of TMR sensors arranged opposite to the magnet on the printed circuit board. The second magnetic sensor is three Hall elements arranged at equal intervals on a circumference centered on the first magnetic sensor.

6. The rotary encoder according to claim 2, wherein The magnet fixed to the rotary shaft is a flat magnet. The first magnetic sensor is a pair of TMR sensors arranged opposite to the magnet on the printed circuit board. The second magnetic sensor is three GMR sensors or AMR sensors arranged at equal intervals on a circumference centered on the first magnetic sensor.

7. The rotary encoder according to claim 1, wherein The processing unit for the first magnetic sensor signal generates a first absolute signal and first incremental A, B, Z, (U, V, W) signals as the first digital data, and the first absolute signal and first incremental A, B, Z, (U, V, W) signals are generated based on the AD conversion data of the output of the first magnetic sensor. The processing unit for the second magnetic sensor signal generates a second absolute signal and second incremental A, B, Z, (U, V, W) signals as the second digital data, and the second absolute signal and second incremental A, B, Z, (U, V, W) signals are generated based on the AD conversion data of the output of the second magnetic sensor.

8. The rotary encoder according to claim 2, wherein The rotary encoder includes a main power supply, a Barkhausen effect power generation power supply, and a secondary battery as a power supply unit, and the output voltages of the main power supply, the Barkhausen effect power generation power supply, and the secondary battery are controlled to a predetermined power. The Barkhausen effect power generation power supply and the secondary battery are the power supplies for backup when the main power supply loses power. The secondary battery has a capacitor, and the capacitor is charged by the Barkhausen effect power generation power supply.

9. A backup control method for a magnetic rotary encoder, which is the backup control method for the magnetic rotary encoder according to claim 1. Characterized in that monitor the first analog signal, the second analog signal, the first digital data, and the second digital data. When the result of monitoring each of the data determines that there is an abnormality in the processing unit of the first magnetic sensor or the first magnetic sensor signal. In the processing unit of the second magnetic sensor signal, for the second analog signal of the second magnetic sensor, a corrected analog signal based on the correction history of the second analog signal is generated, and based on the corrected analog signal and the correction data of the second digital data, the corrected second digital data is generated.

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