Rotary encoder and servo controller including the same

Abstract

To provide a rotary encoder that generates an accurate absolute digital signal by using a magnetic sensor, and comprises a power generator that can secure, in a power outage during which supply of power from a main power supply is cut off, power allowing for smooth execution of processing of stopping a motor and the like.SOLUTION: A rotary encoder comprises: a magnet that is fixed to a rotation shaft; and a function to generate information on a rotation angle and a rotation direction of the rotation shaft from output from a TMR sensor arranged opposite to the magnet. The rotary encoder includes a main power supply, a large Barkhausen effect power generation unit, and a backup power supply charged by the large Barkhausen effect power generation unit. The large Barkhausen effect power generation unit includes a ferromagnetic wire and a coil for power generation, and a first magnetic plate and a second magnetic plate connected with both ends of the ferromagnetic wire. The first magnetic plate and the second magnetic plate extend to the outside of both side faces of the magnet from both ends of the ferromagnetic wire with the magnet therebetween.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rotary encoder and a servo controller including the same, and more particularly to a magnetic absolute encoder equipped with a large Barkhausen effect generating unit and a servo controller including the same. [Background technology]

[0002] Rotary encoders are used to generate information about the angular position and number of revolutions of a rotating shaft driven by a rotating electrical machine. Based on the angular position and number of revolutions of the rotating shaft detected by the encoder, highly accurate absolute and incremental digital signals related to the angular position are generated and output. These signals are used, for example, to control a motor with an encoder as a servo motor in a servo controller. Generally, rotary encoders are equipped with a backup power supply to prevent the loss of position data information in the event that the supply of main power is interrupted. Known examples of such backup power supplies include a generator using the large Barkhausen effect and a generator using a Wiegand wire.

[0003] Patent Document 1 discloses a magnetic absolute encoder that includes a magnetic sensor, a calculation means, a main power supply, and a backup power supply that operates when the main power supply is interrupted, and that during normal operation, can calculate a first single-revolution absolute value and a first multiple-revolution value using a main calculation means that can perform detection operations at high speed and high accuracy, and during backup, can calculate at least a second multiple-revolution value using a low-power backup calculation means to back up the detection operation.

[0004] Patent Document 2 discloses a method for stopping a robot that can reduce power consumption in the standby power source when a capacitor or battery is provided as a standby power source for causing the robot to perform a specified operation when a power outage in the external power source is detected, and that can easily restart the robot and resume normal operation when the power is restored.

[0005] Patent Document 3 discloses a control device capable of suppressing the load acting on the transmission mechanism of a tool magazine during braking, the control device including a power outage determination unit that determines whether or not there is a power outage, and a deceleration unit that decelerates the tool magazine with a time constant shorter than the time constant when there is no power outage if the power outage determination unit determines that there is a power outage. This control device controls a magazine motor equipped with an encoder, and is configured to complete the deceleration process of the tool magazine within the time until the power stored in a storage unit such as a capacitor runs out after a power outage, for example, within 200 ms.

[0006] Patent Document 4 discloses an encoder equipped with an optical or magnetic angle detection unit that employs a composite magnetic wire with a large Barkhausen effect in an electric signal generation unit. This encoder includes a position detection unit that detects the position of a moving part, a magnet with multiple polarities along the moving direction of the moving part, a magnetically sensitive part whose magnetic properties change with a change in the magnetic field accompanying the movement of the moving part, a first magnetic body that guides the magnetic flux lines of the magnet to the magnetically sensitive part, an electric signal generation unit that generates an electric signal based on the magnetic properties of the magnetically sensitive part, and a second magnetic body that is disposed between the magnet and the magnetically sensitive part and guides the magnetic flux lines of one polarity part of the magnet to the other polarity part of the magnet. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2008-180698 A [Patent Document 2] Patent Publication No. 2021-024038 [Patent Document 3] JP 2023-095233 A [Patent Document 4] WO2019 / 188859A1 Summary of the Invention [Problem to be solved by the invention]

[0008] In the magnetic absolute encoder described in Patent Document 1, in the event of a power outage in which the power supply from the main power supply is cut off, the power supply source is switched to a backup power supply, and in order to suppress the power consumption of this backup power supply, only a second multi-rotation value with lower accuracy than during normal operation is calculated. In other words, in the event of a power outage, the multi-rotation value with reduced accuracy is used for control.

[0009] The invention of Patent Document 2 is configured to safely stop the Z-axis of the robot while reducing the amount of power consumed from the standby power supply when a power outage occurs. However, there is no mention of increasing the amount of power in the standby power supply even during a power outage. The invention of Patent Document 3 has a capacitor or a storage battery as a power storage unit for use in the event of a power outage. This power storage unit stores power sufficient to drive and control the machine tool for a predetermined period of time, for example, at least 200 ms, during a power outage. There is no mention of increasing the amount of power in the power storage unit during a power outage.

[0010] The generator of the encoder described in Patent Document 4 is equipped with a power generation unit that utilizes the large Barkhausen effect, and therefore has the function of generating highly accurate absolute digital signals and incremental digital signals and securing sufficient power even during a power outage. On the other hand, the electrical signal generating unit uses multiple permanent magnets arranged around the rotating shaft, and each permanent magnet is configured with a north pole and a south pole stacked in the axial direction. This makes the device complex and large.

[0011] Furthermore, to enable flexible and smooth speed control so that the speed of the object driven by the motor can change quickly and stop slowly, position and angle data with high resolution, such as 27 bits, i.e., single-revolution absolute data and multi-revolution absolute data, is required. However, in many absolute type rotary encoders available on the market, the number of bits for the maximum value of the single-turn absolute data is greater than the number of bits for the maximum value of the multiple-turn absolute data. For example, rotary encoders with 17-bit single-turn absolute data and 16-bit multiple-turn absolute data are available on the market. Rotary encoders with 24-bit single-turn absolute data and 16-bit multiple-turn absolute data are also available on the market. This is thought to be largely related to the use of optical encoders, which consume a lot of power, to generate the multiple-turn absolute data.

[0012] On the other hand, in industrial machines such as robots, many servo motors are used, and a plurality of servo controllers that control these servo motors are configured to be managed by a higher-level controller. In order to control a large number of servo motors in a unified and smooth manner, it is desirable that the number of bits of the maximum value of the single-revolution absolute data is equal to the number of bits of the maximum value of the multiple-revolution absolute data.

[0013] One object of the present invention is to provide a rotary encoder that uses a magnetic sensor to generate a highly accurate absolute digital signal, and is equipped with a power generation device that can secure power to smoothly stop a motor, etc., in the event of a power outage when the power supply from the main power source is cut off. Another object of the present invention is to provide a servo controller equipped with a rotary encoder having a function of generating two types of information, a single rotation absolute signal and a multiple rotation absolute signal, which can smoothly perform control not only during normal operation when power is supplied from a main power supply, but also during a power outage when the power supply from the main power supply is cut off. [Means for solving the problem]

[0014] According to one aspect of the present invention, there is provided a rotary encoder having a magnet fixed to a rotating shaft and a function of generating information on a rotation angle and a rotation direction of the rotating shaft from an output of a magnetic sensor arranged opposite to the magnet, the rotary encoder having a main power supply, a large Barkhausen effect generating unit, and a backup power supply charged by at least the large Barkhausen effect generating unit, the magnetic sensor being a TMR sensor, The encoder further includes a magnetic sensor signal processing unit that converts an analog signal output from the magnetic sensor into an analog signal and generates digital data including two types of information, a one-revolution absolute signal and a multiple-revolution absolute signal, relating to the rotation angle and the rotation direction of the rotating shaft, the magnetic sensor and the processing unit being held in an encoder housing, the TMR sensor being installed on a printed circuit board held in the encoder housing and in a position facing the magnet, and the magnet being a single disk-shaped magnet on which a pair of N-pole and S-pole regions are formed. the large Barkhausen effect power generating unit comprises a ferromagnetic wire and a power generating coil, and a first magnetic plate and a second magnetic plate connected to both ends of the ferromagnetic wire, the first magnetic plate and the second magnetic plate extend from both ends of the ferromagnetic wire to the outside of both side faces of the magnet, sandwiching the magnet between them, the first magnetic plate and the second magnetic plate extend along the both side faces of the magnet at a distance from each other, and the first magnetic plate and the second magnetic plate are shaped symmetrically about an axis of the rotation shaft, sandwiching the magnet between them.

[0015] According to the present invention, it is possible to provide a rotary encoder that generates a highly accurate absolute digital signal using one TMR sensor and is equipped with a power generation device that can secure power sufficient to smoothly stop a motor, etc., in the event of a power outage when the power supply from the main power source is cut off.

[0016] According to another aspect of the present invention, a plurality of the servo controllers are connected to a common host control system that controls a plurality of the servo controllers (A to N). The two types of information, the single rotation absolute signal and the multiple rotation absolute signal, are digital data having the same maximum number of bits. According to the present invention, it is possible to provide a servo controller that can smoothly perform control not only during normal operation when power is supplied from a main power supply, but also during a power outage when the power supply from the main power supply is cut off. [Brief description of the drawings]

[0017] [Figure 1] 1 is a functional block diagram showing an example of the configuration of a rotary encoder according to a first embodiment of the present invention; [Diagram 2] 1 is a block diagram showing an example of the configuration of a servo controller according to a first embodiment of the present invention. [Diagram 3] 2 is a vertical cross-sectional view showing a configuration example of a magnetic sensor and a power supply unit in the first embodiment. FIG. [Figure 4] 3 is a plan view of an encoder housing showing a configuration example of a large Barkhausen effect power generating unit in the first embodiment. FIG. [Diagram 5] 4 is a vertical cross-sectional view showing the positional relationship and the relationship between magnetic flux lines among the magnet, magnetic sensor, and power supply unit shown in FIG. 3. [Figure 6] 4 is a diagram showing the rotation of a magnet and the positional relationship between a first magnetic plate and a second magnetic plate of a large Barkhausen effect generating unit in the first embodiment. FIG. [Figure 7] FIG. 2 is a diagram conceptually explaining the function of a large Barkhausen effect power generation unit in the first embodiment. [Figure 8A] 4 is a diagram showing an example of a relationship between a magnet, a first magnetic plate, and a second magnetic plate in the first embodiment. FIG. [Figure 8B] 13 is a diagram showing another example of the relationship between the magnet and the first and second magnetic plates. FIG. [Figure 8C] 13 is a diagram showing another example of the relationship between the magnet and the first and second magnetic plates. FIG. [Figure 8D]13 is a diagram showing another example of the relationship between the magnet and the first and second magnetic plates. FIG. [Figure 8E] 13 is a diagram showing another example of the relationship between the magnet and the first and second magnetic plates. FIG. [Figure 8F] 5 is a diagram showing an example of characteristics of a first magnetic plate and a second magnetic plate in the first embodiment. FIG. [Figure 9] FIG. 2 is a diagram illustrating an example of the circuit configuration of a power supply unit in the first embodiment. [Figure 10] 4 is a diagram showing the relationship between the rotation of a magnet and the output of a TMR sensor in the first embodiment. FIG. [Figure 11] 5 is a flowchart showing signal processing of a processing unit for a first TMR sensor signal in the first embodiment. [Figure 12] 4A to 4C are diagrams illustrating the output of a first TMR sensor accompanying rotation of a magnet, digitization of the sensor signal, and processing for making it absolute in the first embodiment. [Figure 13] 4 is a time chart showing the operation of the power supply unit in the first embodiment, illustrating an example of the relationship between the power supply and the output signal of the rotary encoder when the main power supply goes into a power outage after going from a normal state. FIG. [Figure 14] 1 is a time chart showing the operation of the power supply unit, etc., illustrating an example of the relationship between the power supply and the output signal of the rotary encoder from a normal state of the main power supply to a power outage and recovery of the power supply. FIG. [Figure 15] FIG. 11 is a diagram showing another example of the configuration of the circuit of the power supply unit according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] First, a rotary encoder according to a first embodiment of the present invention will be described. First, the overall configuration and functions of the rotary encoder according to the first embodiment of the present invention will be described with reference to Figs. FIG. 1 is a functional block diagram of a configuration example of a rotary encoder, FIG. 2 is a configuration example of a servo controller, and FIGS. 3 to 5 are diagrams showing configuration examples of a TMR sensor and a power supply unit. The rotary encoder 10 includes a TMR sensor unit 11, a power supply unit 12, a temperature sensor 13, a system control unit 14, and two processing units for magnetic sensor signals (a processing unit 15 for a first TMR sensor signal, and a processing unit 16 for a second TMR sensor signal). The rotary encoder 10 further includes a flat disk-shaped magnet 110 that is magnetized with one pole each of N and S polarities, i.e., has only one set of N and S polarities. The disk-shaped magnet 110 has a pair of N-pole and S-pole regions formed in the radial direction with a boundary line 1101 (see FIG. 4) passing through its center as a boundary, and has a flat front surface, a back surface, and a side surface. The magnet 110 is, for example, a neodymium magnet, and is fixed to one end surface of the rotating shaft 510 by a holding member 1102, an adhesive, or the like, as shown in FIG. 3. Instead of the neodymium magnet, a samarium-cobalt magnet or a ferrite magnet may be used.

[0019] The system control unit 14 includes an initial setting section 141, a power supply monitoring and control unit 143, an encoder input / output control unit 144, a safety control unit 145, a serial / parallel signal transmission / reception unit 146, etc. The initial setting section 141 has a function of setting the type of motor, the number of poles, the origin position, the output conditions of the rotary encoder, etc., according to the origin and output conditions input via a user interface 142. 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.

[0020] The safety control unit 145 monitors the output states of the first TMR sensor 111, the second TMR sensor 112, the first TMR sensor signal processing unit 15, and the second TMR sensor signal processing unit 16, and if any of them fail, it performs the necessary processing to safely stop the operation of the rotary encoder, thereby making the rotary encoder function as a safety encoder. The serial / parallel signal transmitting / receiving unit 146 has a function of converting various information into parallel signals or serial signals and transmitting / receiving the same between each rotary encoder 10 (A to N) and the corresponding servo controller 60 (A to N) (see FIG. 2). This information includes single rotation absolute data 50 and multiple rotation absolute data 52. The single rotation absolute data 50 and multiple rotation absolute data 52 are digital data with the same maximum number of bits.

[0021] As shown in Fig. 2, each servo controller 60 (A to N) is connected to one upper control system 70, and this upper control system 70 controls the motors 80 (A to N) to be controlled via each servo controller. The upper control system 70 controls normal operation of all motors 80 (A to N) when the main power supply is normal, and stops operation and restarts them when the main power supply is lost and the power supply stops. A rotating shaft 510 on which a rotary encoder is attached is driven directly by a rotating electric machine such as a motor, or indirectly via a speed change mechanism 82 or the like. The upper control system 70 and each servo controller (A to N) use the same high-bit digital data for each corresponding motor to perform normal operation when the main power supply is normal, and operation shutdown and restart when the power supply is cut off due to a loss of the main power supply.

[0022] The TMR sensor unit 11 has a first TMR sensor 111, a second TMR sensor 112, and a temperature sensor 113, which are arranged on a printed circuit board 19 (see FIG. 3). The first TMR sensor 111 and the second TMR sensor 112 are two sets of TMR sensors having the same specifications and therefore the same output characteristics. (In the following explanation, unless otherwise necessary, only the first TMR sensor 111 will be explained, and the explanation of the second TMR sensor 112 will be omitted.) The printed circuit board 19 is fixed to the upper end of a cylindrical encoder housing 40. The encoder housing 40 is made of aluminum, for example, and is fixed to an end cover of a rotating device, such as a motor 80, to which the encoder is attached. Alternatively, an equivalent of the encoder housing 40 may be formed integrally with a member constituting an end cover or a storage container of the rotating device. For convenience, such a housing is also defined as an encoder housing in the present invention. A rotating shaft 510 of the rotating device is positioned in a hollow portion 41 of the encoder housing 40, and a magnet 110 is fixed to the end of the rotating shaft. The encoder housing 40 is covered with a cover 46 made of a magnetic material, and the end cover side of the motor is also covered with a magnetic material, so that the inside of the encoder housing 40 is magnetically shielded. The first TMR sensor 111 is located at the axis O of the rotating shaft 510. S -O S The second TMR sensor 112 is disposed on the lower side of the printed circuit board 19, i.e., on the side facing the single magnet 110, at a position corresponding to the axis O. S -O S are disposed on the upper surface of the printed circuit board 19 at positions corresponding to the

[0023] 1, the first TMR sensor signal processing unit 15 includes an analog signal processing unit 151 that processes the first analog signal, a one-revolution absolute signal generating unit 152, and a multi-revolution absolute signal generating unit 153. The first TMR sensor signal processing unit 15 has a function of AD converting the analog signal that is the output of the first TMR sensor 111, and generating two systems of information of high-resolution (e.g., 27 bits / revolution) absolute signals as first digital data. In addition, the position of one end of the boundary line 1101 between the north pole region and the south pole region of the magnet 110 is a specific position in the circumferential direction on the rotation axis, that is, the origin position (Z0) corresponding to the rising point of the A-phase pulse.

[0024] The analog signal processing unit 151 receives sampling data of the first analog signal (sine signal, cosine signal) of the first TMR sensor 111 as time-series data, converts it to digital values ​​using a 64-bit AD converter (SIN) 1511 and an AD converter (COS) 1512, and these converted values ​​are correlated with the rotation speed Nx of the rotating shaft and the data of the temperature sensors 13 and 113, and recorded in the memory 1513 as time-series data.

[0025] The one-revolution absolute signal generating unit 152 generates one-time absolute data including information on the rotation angle and rotation direction within one rotation based on the time-series data in the memory 1513 and records it in the memory, with the origin position (Z0) as the reference. The multi-rotation absolute signal generating unit 153 has a rotation speed and rotation direction detection section 1531, a single-rotation absolute signal generating section 1532, and a multi-rotation absolute signal generating section 1533. Based on the time-series data in the memory 1513, a multi-rotation absolute signal including information on the rotation speed, rotation direction, and rotation angle with respect to the origin position (Z0) is generated and recorded in the memory.

[0026] The second TMR sensor signal processing unit 16 includes an analog signal processing unit 161 , an AD converter 162 , and a digital signal processing unit 163 . The second TMR sensor signal processing unit 16 performs AD conversion on the second analog signal that is the output of the second TMR sensor 112, and generates high-resolution (e.g., 27 bits / revolution) absolute signal information as second digital data. The signal processing of the second TMR sensor signal processing unit 16 is the same as the signal processing of the first TMR sensor signal processing unit 15, and therefore a description thereof will be omitted. Depending on the application, the second TMR sensor 112 may be omitted, and a rotary encoder may be formed by the TMR sensor 111 and a processing unit for a corresponding signal.

[0027] Based on the output of the encoder input / output control unit 144, either the first digital data or the second digital data, for example the first digital data, is converted as an absolute signal into transmission data (BUS) for serial transmission from the rotary encoder 10, and transmitted from the serial / parallel signal transmitting / receiving unit 146 to the servo controller 60 via a communication cable.

[0028] Note that the functional blocks shown in Fig. 1 are shown as examples. The functional blocks may be divided arbitrarily, and it goes without saying that the functional blocks may be realized by a common program, or a specific functional block may be realized by a plurality of different programs or IC circuits. Alternatively, each of the above functions can be realized by installing a program for executing each of the above functions in a microcomputer having a CPU and memory. The power supply unit 12 includes a main power supply 121, a large Barkhausen effect power supply 122 having a large Barkhausen effect generating unit 115, and a backup power supply 123 having a capacitor, which, together with the main power supply 121, function as a power supply that supplies power to the rotary encoder 10.

[0029] As shown in FIG. 3, the parts of the rotary encoder 10 excluding the disk-shaped magnet 110 and the large Barkhausen effect power generation unit 115, i.e., the power supply unit 12, the temperature sensor 13, the system control unit 14, the first TMR sensor signal processing unit 15, and the second TMR sensor signal processing unit 16, are formed or mounted on a single printed circuit board 19. In particular, the system control unit 14, the first TMR sensor signal processing unit 15, and the second TMR sensor signal processing unit 16 are realized as a dedicated FPGA 18 (Field Programmable Gate Array), or as an ASIC (Application Specific Integrated Circuit), or as an IC circuit chip using a general-purpose single-chip microcomputer, and are mounted on a printed circuit board 19. In addition, the AD converter 152 and the AD converter 162 are also mounted on the printed circuit board 19 as an ASIC (or FPGA). In addition, a capacitor constituting the backup power supply 123 is also mounted on the printed circuit board 19.

[0030] The system control unit 14, the first TMR sensor signal processing unit 15, and the second TMR sensor signal processing unit 16 are functionally divided blocks, and these functions are realized by writing programs in the digital signal processing unit, SSC interface, incremental interface, etc. of the FPGA or ASIC. The FPGA includes a ROMRAM and at least one rewritable (overwritable) non-volatile memory, and is connected to the CPU via a bus. As the rewritable (overwritable) non-volatile memory, EEPROM, FRAM (registered trademark), (Ferroelectric Random Access Memory), etc. may be used.

[0031] The large Barkhausen effect power generating unit 115 has its main body installed in a storage section 42 formed by recessing a part of the encoder housing 40. The large Barkhausen effect power generating unit 115 includes a ferromagnetic wire (or a composite magnetic wire) 1152 such as a Wiegand wire, a power generating coil 1154 provided around the ferromagnetic wire 1152, and a first magnetic plate 1156 and a second magnetic plate 1158 connected to both ends of the ferromagnetic wire 1152. These magnetic plates 1156 and 1158 are made of the same magnetic material and are aligned with the axis O of the rotating shaft 510. S -O SThe first magnetic plate 1156 and the second magnetic plate 1158 are disposed at the same position (height) as the magnet 110 in the direction of the magnet 1152, and extend to the outside of both sides of the disk-shaped magnet 110, and these magnetic plates extend apart along both sides of the magnet. That is, the midpoint of the thickness (axial length) of the first magnetic plate 1156 and the second magnetic plate 1158 is located on the line O connecting the midpoint of the thickness (axial length) of the magnet 110 and the center of the ferromagnetic wire 1152. mgR -O mgR However, this is an ideal case. In practice, it is sufficient that the first magnetic plate and the second magnetic plate are configured to receive magnetic flux lines that are mainly parallel to the surface of the magnet or in a direction close to the outer periphery thereof, and to suppress the influence of magnetic field interference on the magnetic sensor. Therefore, it is sufficient that the midpoint of the thickness of these magnetic plates is within or near the range between the front and back surfaces of the magnet. In the present invention, including this range, the first magnetic plate and the second magnetic plate are defined as being at the same position (height) as the magnet.

[0032] As shown in FIG. 4, the first magnetic plate 1156 and the second magnetic plate 1158 have a predetermined gap Ga between both sides of the magnet 110 so that the magnetic flux lines from the N-pole region and the S-pole region are appropriately guided to the first magnetic plate 1156 and the second magnetic plate 1158 by the rotating magnetic field caused by the rotation of the magnet 110. That is, these magnetic plates extend along tangents 110a, 110b of both sides of the disk-shaped magnet parallel to the axis of symmetry, and are spaced apart from the tangents by the gap Ga. If the gap Ga is narrow, these magnetic plates are likely to cause magnetic field interference that affects the output of the TMR sensor unit 11. On the other hand, if the gap is too wide, these magnetic plates cannot obtain sufficient magnetic flux lines from both the N-pole and S-pole regions. Taking these factors into consideration, the gap Ga may be appropriately set. In addition, the ends of these magnetic plates on the magnet side are open ends sandwiching the magnet 110.

[0033] When the rotating shaft 510 is at a position corresponding to the origin position of the motor, the boundary line 1101 between the north pole area and the south pole area of ​​the magnet passes through the center of the flat surface of the magnet.S -O S (See Figure 3) mgV -O mgV The first magnetic plate 1156 and the second magnetic plate 1158 shown here are strip-shaped corner members, and on the side surface of the magnet 110, their center lines O G1 , O G2 is a straight line O mgR -O mgR (axis of symmetry) on both sides of the magnetic plates. mgR -O mgR is a straight line O mgV -O mgV The axis of symmetry is perpendicular to the axis O and passes through the center of the disk-shaped magnet 110. In consideration of manufacturing tolerances, it is sufficient for the axis of symmetry to pass through the center of the disk-shaped magnet 110 or its vicinity (hereinafter, near the center of the magnet). Also, the first magnetic plate 1156 and the second magnetic plate 1158 are aligned with each other with respect to the axis O. S -O S Since the surface has a thickness in the direction, it goes without saying that the surface has a shape that is linearly symmetrical with respect to the axis of symmetry on a plane at each position of the thickness. 4, the first magnetic plate 1156 and the second magnetic plate 1158 are shaped to be line-symmetrical with respect to the magnet 110 at least near the side surface of the magnet. That is, the first magnetic plate 1156 and the second magnetic plate 1158 are shaped to be line-symmetrical with respect to the axis of symmetry. Therefore, the first magnetic plate 1156 and the second magnetic plate 1158 face the side surface of one magnet 110 with the same magnetic characteristics.

[0034] As long as the condition of line symmetry is satisfied, the cross-sectional shape of the first magnetic plate 1156 and the second magnetic plate 1158 can be any plate-like or rod-like shape, such as a rectangle, a circle, an ellipse, or a trapezoid. As long as the condition of line symmetry is satisfied, non-parallel portions may be present. Furthermore, the shapes of the first magnetic plate 1156 and the second magnetic plate 1158 may be different in a section away from the magnet 110 and close to the large Barkhausen effect generating unit 115, if there are structural constraints. However, it is desirable that the magnetic characteristics for guiding magnetic flux lines are the same. In addition, it is desirable that the free ends of the first magnetic plate 1156 and the second magnetic plate 1158, i.e., the respective tips 1156a, 1158a, protrude in a tapered shape, for example, a pyramidal or conical shape. This makes it easier to collect magnetic flux lines. The protruding direction of the tip of each free end may be in the direction of the magnet 110, i.e., toward the center of the magnet 110, or in a direction perpendicular to the axis of symmetry.

[0035] FIG. 5 shows the positional relationship between the magnet, the TMR sensor, and the power supply unit, and the relationship between the magnetic flux lines. Due to the rotating magnetic field, the magnetic flux line φ1 passes through the first TMR sensor 111, the magnetic flux line φ2 passes through the second TMR sensor 112, and the magnetic flux line φ3 passes through the first and second magnetic plates 1156 and 1158. Therefore, it is necessary to configure the first magnetic plate 1156 and the second magnetic plate 1158 so that the magnetic flux line φ3, which affects the output of the large Barkhausen effect generating unit, is optimized while the magnetic flux line φ1 and the magnetic flux line φ2, which are directed from the N pole to the S pole of the magnet, keep the first and second TMR sensors 111 and 112 in a suitable operable state. That is, φ1 to φ3 may be set appropriately depending on the size of the magnet 110 (diameter of the rotating shaft), the strength H of the magnetic field supplied by the magnet, the magnetic flux density B, the characteristics of the TMR sensor, the output required for the large Barkhausen effect generating unit, and the like. In addition, the magnetic permeability of the shape material of these magnetic plates must also be taken into consideration.

[0036] In the present invention, the magnetic flux lines φ1 toward the first TMR sensor are mainly composed of magnetic flux lines that extend axially upward (perpendicular to the surface of the magnet) from the inside of the N-pole region close to the boundary line 1101 of the magnet and then toward the inside of the S-pole region, and the magnetic flux lines φ2 toward the second TMR sensor are mainly composed of magnetic flux lines that extend axially upward from the outside of the N-pole region away from the boundary line 1101 and then toward the outside of the S-pole region. In contrast, the magnetic flux lines φ3 used in the large Barkhausen effect power generating unit are mainly magnetic flux lines that extend from the outer side of the magnet and the side of the magnet in a horizontal or nearly horizontal direction relative to the magnet surface, and further outward toward the outside of the south pole region and the side of the magnet. In this way, in order to suppress the effects of magnetic field interference on the magnetic flux lines φ1 heading toward the first TMR sensor and the magnetic flux lines φ2 heading toward the second TMR sensor, the first magnetic plate and the second magnetic plate are configured to mainly receive the magnetic flux lines φ3 that extend in a horizontal or nearly horizontal direction. For example, if the diameter of the rotating shaft 510 is about 6.0 to 8.0 mm, the thickness of the printed circuit board is about 1.0 to 1.2 mm, the diameter of the magnet is about 5.0 to 10.0 mm, and the thickness of the magnet is about 3 mm, the gap G1 is preferably about 0.5 to 3.0 mm. The gap Ga is also preferably about 0.5 to 3.0 mm.

[0037] Next, with reference to Figs. 6 and 7, the relationship between the rotating magnetic field of the magnet, i.e., the rotation angle of the rotation axis, and the first and second magnetic plates in the large Barkhausen effect generating unit in the first embodiment will be described. FIG. 6 is a diagram showing the rotation of the N-pole region and S-pole region of the magnetic field with the rotation of the magnet, and the positional relationship with the first and second magnetic plates of the large Barkhausen effect generating unit. That is, the areas where the magnet 110, the first magnetic plate 1156, and the second magnetic plate 1158 face the N-pole region and the S-pole region, respectively, when the magnet 110 is in each of the rotation positions (A) to (I) are shown by diagonal lines. The area size of this facing area is related to the density of the magnetic flux lines φ3 from the magnet 110 to the first and second magnetic plates 1156 and 1158. That is, it is related to the direction of the magnetic flux lines φ3 in the first and second magnetic plates 1156 and 1158. It is needless to say that in practice, the direction and density of the magnetic flux lines φ3 are not determined only by the area size relationship with the rotation of the magnet, but it is useful for understanding the general tendency. 6A shows a state where magnet 110 is at the origin position (Z0), that is, at a rotation angle of 0 degrees. In this state, first magnetic plate 1156 and second magnetic plate 1158 face the N-pole region and S-pole region of magnet 110 under the same conditions. In other words, first magnetic plate 1156 and second magnetic plate 1158 receive magnetic flux lines φ from the N-pole region and S-pole region under the same conditions.

[0038] From this state, when the magnet 110 is rotated 45 degrees (B), the first magnetic plate 1156 faces the N-pole region with a wide area, and the second magnetic plate 1158 faces the S-pole region with a wide area. Furthermore, when the magnet 110 is rotated 90 degrees (C), the first magnetic plate 1156 faces only the N-pole region, and the second magnetic plate 1158 faces only the S-pole region. In this way, as the magnet 110 rotates from 0 degrees to 90 degrees, the first magnetic plate 1156 faces the N-pole region with a wider area, and the second magnetic plate 1158 faces the S-pole region with a wider area. Furthermore, when the magnet 110 is rotated 135 degrees (D), the facing area of ​​the first magnetic plate 1156 to the N-pole region decreases, and the facing area of ​​the second magnetic plate 1158 to the S-pole region decreases. In this way, as the magnet 110 rotates, the facing areas of the first magnetic plate 1156 and the second magnetic plate 1158 to the N-pole region and the S-pole region change. 6(E), (F), and (G), as the magnet 110 rotates beyond 180 degrees, the areas of the first magnetic plate 1156 and the second magnetic plate 1158 that face the N-pole region and the S-pole region increase and decrease significantly in a periodic manner. This means that as the magnet 110 rotates, the density and direction of the magnetic flux lines φ3 in these magnetic plates change.

[0039] FIG. 7 is a diagram conceptually explaining the function of a large Barkhausen effect power generation unit. One end of each of the first magnetic plate 156 and the second magnetic plate 1158 is connected to the ferromagnetic wire 1152 of the large Barkhausen effect generating unit 115, and the other end opposite thereto is an open end, sandwiching the magnet 110 therebetween. As is clear from FIG. 6, as the magnet 110 rotates from 0 degrees to 90 degrees, the density of the magnetic flux lines φ3 from the N-pole region of the magnet to the S-pole region, i.e., from the magnet to the S-pole region via the first magnetic plate 1156 and the second magnetic plate 1158, increases as shown in (A), (B), and (C) of FIG. 7. That is, up to 90 degrees, the magnetic flux supplied to the power generating coil 1154 of the large Barkhausen effect power generating unit 115 increases. After that, when the angle exceeds 90 degrees, the density of the magnetic flux lines φ3 in the direction from the N-pole region of the magnet to the first magnetic plate 1156 to the second magnetic plate 1158 to the S-pole region decreases, and as the magnet rotates further, the density of the magnetic flux lines φ3 increases in the opposite direction to the direction from the second magnetic plate 1158 to the first magnetic plate 1156, i.e., from the N-pole region of the magnet to the S-pole region via the second magnetic plate 1158 and the first magnetic plate 1156.

[0040] 6(H) and 6(I), the density of the magnetic flux lines φ3 flowing from the second magnetic plate 1158 to the first magnetic plate 1156 decreases. With this reversal of the direction of the magnetic flux lines φ3 with each rotation of the magnet 110, the direction of the magnetic flux lines flowing through the ferromagnetic wire 1152 of the large Barkhausen effect generating unit 115 is reversed, and a pulsed power output is obtained in the power generating coil 1154, as shown in FIG. 7(D).

[0041] One of the features of the present invention is that a single disk-shaped magnet 110 having only one pair of polarities N, S magnetized in the radial direction and fixed to the rotating shaft 510 is used as an analog signal source for the magnetic sensor and a power generating device for the large Barkhausen effect generating unit 115. The first magnetic plate and the second magnetic plate are configured to receive magnetic flux lines φ3 that are parallel or close to the surface of the magnet in an outward direction to suppress the influence of magnetic field interference on the magnetic sensor in order to suppress the influence of magnetic field interference on the magnetic flux lines φ1 toward the first TMR sensor and the magnetic flux lines φ2 toward the second TMR sensor. As a result, as one magnet rotates, the density of the magnetic flux lines φ3 direction in the first magnetic plate 1156 and the second magnetic plate 1158 increases and decreases periodically as shown in Figs. 6 and 7, and the polarity and density of the magnetic flux lines φ3 received by the first magnetic plate 1156 and the second magnetic plate 1158 also change. By combining a single magnet fixed to the end face of the rotating shaft 510 with a first magnetic plate 1156 and a second magnetic plate 1158 extending outward from both sides of the magnet, it is possible to obtain a large power generation output while maintaining a compact configuration of the large Barkhausen effect power generation unit 115.

[0042] Next, the configuration of the first magnetic plate and the second magnetic plate will be described. 8A to 8E are diagrams showing an example of the relationship between the disk-shaped magnet and the first and second magnetic plates 1156 and 1158 in the first embodiment. As described above, the first and second magnetic plates 1156 and 1158 are arranged on the side of the magnet 110, and are symmetrical with respect to the axis of symmetry, and extend to the outside of both sides of the magnet, and the first and second magnetic plates extend apart along both sides of the magnet. If the diameter of the magnet is Dm and the length of the first and second magnetic plates extending apart to the outside of both sides of the magnet is Lm1, then, as an example, as shown in FIG. 8A, Lm1 is approximately equal to Dm.

[0043] However, in order to obtain a predetermined output from the large Barkhausen effect power generating unit 115, the characteristics shown in FIG. 6 and FIG. 7 do not need to be completely consistent on both the positive and negative sides, and may differ slightly. Therefore, as shown in FIG. 8B, the length Lm2 may be slightly shorter than Dm. Also, as shown in FIG. 8C, even if the first magnetic plate and the second magnetic plate are not parallel, it is acceptable as long as the inclination angle Θ between them is small and the condition of line symmetry is satisfied. For the same reason, the first magnetic plate and the second magnetic plate may be slightly curved inward or outward from each other. Furthermore, as shown in FIG. 8D, the length Ls1 may be half of Dm. Note that, as shown in FIG. 8E, the tips of the first magnetic plate and the second magnetic plate may face inward in the radial direction.

[0044] Next, FIG. 8F is a diagram showing the characteristics of the first magnetic plate and the second magnetic plate in the first embodiment. In the large Barkhausen effect power generation, a pulse output is obtained by a sudden change in the magnetic flux density from positive to negative or from negative to positive with the rotation of the magnet. On the other hand, a large magnetic flux density in a state where the magnetic flux density has the same polarity, for example, a large magnetic flux density at the position around 90 degrees or 270 degrees shown in FIG. 7, does not contribute much to the output of the large Barkhausen effect power generation. Therefore, it is desirable to configure the magnetic flux density of the first magnetic plate and the second magnetic plate to saturate at the position around 90 degrees or 270 degrees.

[0045] Next, an example of the circuit configuration of the power supply unit in the first embodiment will be described with reference to FIG. The main power supply 121 of the power supply unit 12 includes a main power supply section 1211 in which power supplied from, for example, a commercial power supply is converted into DC power and controlled to a predetermined DC voltage Vcc, for example, 5 V. This main power supply section 1211 supplies power to an output terminal 125 of an output section 124 via a diode 1221. The large Barkhausen effect power supply 122 outputs a positive and negative pulse waveform at 180 degree intervals for each rotation of the rotating shaft from the large Barkhausen effect power generation unit 115. This power is supplied as DC power to the output terminal 125 via a full-wave waveform circuit 1222, a smoothing circuit 1223, and a diode 1224. The backup power supply 123 includes capacitors 1232 and 1233 connected in parallel to the output terminal of the large Barkhausen effect power supply 122 via a diode 1231. The terminals of these capacitors are connected to an output terminal 125 via a diode 1231. The backup power supply 123 functions as a power supply that supplies power to the rotary encoder 10 when the main power supply fails. The power obtained by the large Barkhausen effect power generating unit 115 is stored in the capacitors 1232 and 1233 that constitute the backup power supply 123, and the power of this backup power supply 123 can be used as a power supply for the rotary encoder in place of the main power supply, and even for a long period of time after the main power supply fails. The backup power supply 123 may be configured to be supplied with power individually from both the main power supply 121 and the large Barkhausen effect power supply 122. The output section 124 has a current / voltage limiting circuit 1241 and, under the control of the power supply monitoring and control unit 143 , controls so that the output voltage of the output section 124 becomes a predetermined voltage Vcc at the terminal 125 . The large Barkhausen effect power supply 122 of the present invention generates a large amount of power even in a compact configuration. Therefore, a nickel-cadmium battery, a nickel-metal hydride battery, a lithium-ion battery, or an all-solid-state battery may be adopted as the backup power supply 123 so that sufficient power can be supplied for a long period of time even after a power outage of the main power supply.

[0046] The power supply monitoring and control unit 143 controls each of the power supplies, the main power supply 121, the large Barkhausen effect power supply 122, and the backup power supply 123, monitors whether they are functioning normally, and if there is an abnormality, displays the abnormality. It also controls the power supply switching and the stopping of the rotary encoder. The power supply line connected to the output terminal 125 of the power supply unit 12 is configured as three electrically independent lines, and power is supplied to the system control unit 14, the first TMR sensor signal processing unit 15, and the second TMR sensor signal processing unit 16.

[0047] 10 is a diagram showing the relationship between the rotation of the magnet and the output of the TMR sensor in the first embodiment. As the magnet rotates, the relationship between the opposing north and south poles changes, and the magnetization directions of the free layer and pinned layer of the TMR sensor change. As a result, sine wave and cosine wave signals are output from the TMR sensor.

[0048] Next, the digitization and absolute conversion process of the first TMR sensor signal in the first TMR sensor signal processing unit 15 will be described with reference to FIG. 11 and FIG. The first TMR sensor signal processing unit 15 acquires information on the origin of the rotation axis and the number of high bits to be generated from the initial setting values ​​(S101). Next, AD conversion data of the first TMR sensor signal (sine and cosine waves) is obtained from the memory (S102). That is, as shown in (A) of Fig. 12, the first TMR sensor (TMR sensor) 111 outputs a first analog signal of 360 degrees (mechanical angle) each for one period of a sine wave (A-phase signal) and a cosine wave (B-phase signal) corresponding to one rotation of the rotation shaft. The data of the rotation angle (mechanical angle) and amplitude of the first analog signal, and the number of rotations Nx are associated with the temperature Ta of the temperature sensor 13, etc., by the analog signal processing unit 151 of the processing unit 15 of the first TMR sensor signal, and are recorded in the memory. Furthermore, θ is calculated by an arctangent function calculation based on the A-phase signal (Asin θ) and the B-phase signal (Cos θ), and is recorded in memory (S103).

[0049] That is, as shown in (B) and (C) of FIG. 12, analog signals (sine signal, cosine signal) are input to an AD converter 152, quantized, and converted into a multi-divided digital signal by an interpolation process, and then converted into digital values ​​containing information on phase A and phase B. These converted values ​​are associated with the rotation speed Nx, rotation direction, temperature Ta, etc., and recorded in memory.

[0050] The first TMR sensor signal processing unit 15 calculates absolute values ​​of the rotation direction and rotation angle based on the AD converted data and origin information, assigns memory addresses to the absolute values, and records them in memory as one-revolution absolute data (S104). Furthermore, multi-rotation information including the direction of rotation and the number of rotations is generated from the values ​​of the origin information, the A-phase signal, and the B-phase signal and recorded in memory (S106), and high-bit single-rotation absolute information is generated based on the calculated θ (S107). Based on this data, the single-rotation absolute information and the multiple-rotation information, high-bit multiple-rotation absolute data is generated and recorded in memory (S108). In this way, a single rotation absolute signal and a multiple rotation absolute signal are generated and recorded in memory.

[0051] At the time of startup, power is supplied from the main power supply to the rotary encoder 10. After startup, power is supplied to the rotary encoder from the main power supply or the large Barkhausen effect power supply 122. 13 is a time chart showing the operation of the power supply unit 12. That is, it is a diagram showing an example of the power supply switching state when the main power supply goes out from a normal state. In this example, when the power supply of the power supply is in a normal state, power is supplied from the main power supply to the rotary encoder 10. First, information on the normality judgment of each power supply is obtained from the initial setting unit (S1201). Then, the power supply monitoring and control unit 143 monitors the power supply monitoring data of each power supply (121, 112, 123) of the power supply unit 12 (S1202). If the voltage of the main power supply 121 is normal (NO in S1203), absolute signals with the same high bit number are generated in single rotation mode and multi-rotation mode based on the output of the first and second TMR sensors (1204). This process is continued until the end of normal operation (S1205, S1206). If the voltage of the main power supply 121 has dropped in S1202 (YES in S1203), the state of the large Barkhausen effect power supply 122 is confirmed (S1210), and if normal, the power supply is switched to the large Barkhausen effect power supply (S1211). Then, based on the output of the first and second TMR sensors, absolute signals with the same high bit number are generated in single rotation mode and multiple rotation mode (1212). This process is continued until the end of the stop process (S1213, S1214). If the power generation output of the large Barkhausen effect power supply 122 is absent or reduced (NO in S1210), the state of the backup power supply 123 is checked (S1220). If the voltage of the backup power supply 123 is normal, the power supply is switched to the backup power supply (S1221). Then, based on the output of the first TMR sensor, absolute signals with the same high bit number are generated in single rotation mode and multiple rotation mode. Meanwhile, the process of the second TMR sensor is stopped (S1222). This process is continued until the end of the stop process (S1223, S1224). If the voltage of the backup power supply 123 has dropped (NO in S1220), a power supply error is displayed (S1230), and processing to end the operation of the encoder is performed (S1231). Even when the main power supply unit 1211 is unable to supply power due to, for example, a power outage or failure of the main power supply, power continues to be supplied to the rotary encoder 10 from the large Barkhausen effect power supply 122, which is generated as the rotating shaft rotates, and also from the backup power supply 123.

[0052] FIG. 14 is a time chart showing the operation of the power supply unit and the like, illustrating an example of the relationship between the power supply and the output signal of the rotary encoder from a normal main power supply state to a power outage and recovery of the power supply. When a power outage occurs at time t1, the servo controller starts a shutdown process to safely stop the robot or other operating equipment and to allow smooth restart of the equipment. The large Barkhausen effect power supply 122 of the present invention generates a large amount of power even with a compact configuration. Therefore, even during the process of decelerating the rotation of the motor during the shutdown process, the large Barkhausen effect power supply 122 can charge the backup power supply 123 with sufficient power. As the number of rotations of the rotating shaft decreases over time, the output of the large Barkhausen effect generator decreases, and when it becomes less than one rotation, it is no longer able to supply power output. In this state, the charge stored in the capacitor 1233 of the backup power supply 123 supplies power of the voltage Vcc to the rotary encoder 10. As a result, the rotary encoder 10 can generate information on the rotation angle of the rotating shaft for a relatively long time after a power outage, for example, even after time t2 when the rotation of the rotating shaft has completely stopped, and can perform a smooth stopping process.

[0053] Next, a second embodiment of the present invention will be described with reference to Fig. 15. Fig. 15 is a diagram showing another example of the circuit configuration of the power supply unit 12 of the present invention. In this power supply unit, the capacitor 1233 of the backup power supply 123 is configured by connecting multiple capacitors C1 (12331), C2 (12332), C3 (12333), and C4 (12334) in parallel. The capacitors C2, C3, and C4 are connected to the smoothing capacitor C0 via multiple Zener diodes Z2, Z3, and Z4 with different Zener voltages (Vz), and are configured so that the capacitors C2, C3, and C4 are charged in sequence to a voltage slightly higher than Vcc as the capacitor voltage rises. Transistor switches SW1 (1236), SW2 (1237), and SW3 (1238) are provided between the capacitors C1, C2, C3, and C4, and are controlled by a control circuit (not shown) so that the output voltage of the capacitor C1 is maintained at Vcc for a long period of time. According to this embodiment, the rotary encoder 10 can generate information on the rotation angle of the rotating shaft for a relatively long time after a power outage, for example, for a longer time even after time t2 when the rotation of the rotating shaft has completely stopped, and can perform a smooth stopping process.

[0054] The rotary encoder of the present invention can be used in various motors such as brushless motors and stepping motors. It can also be widely applied to various rotating electrical devices such as synchronous motors and induction motors. The present invention can also be applied to servo controllers using these rotating electrical devices. [Explanation of symbols]

[0055] 10 Rotary Encoder 11 TMR sensor unit 110 Magnet 111 First TMR sensor 112 2nd TMR sensor 115 Large Barkhausen Effect Power Unit 1156 1st magnetic plate 1158 Second magnetic plate 12 Power supply unit 121 Main power supply 122 Large Barkhausen effect power supply 123 Backup Power 13 Temperature Sensor 14 System Control Unit 141 Initial setting section 143 Power supply monitoring and control unit 144 Encoder I / O control unit 146 Serial / Parallel Signal Transmitting / Receiving Unit 15 1st TMR sensor signal processing unit 151 Analog signal processing section of the first TMR sensor 1511 AD converter (SIN) 1512 AD converter (COS) 152 1-revolution absolute signal generation unit 153 Multi-rotation absolute signal generation unit 16 Second TMR sensor signal processing unit 18 FPGA or ASIC 19 Printed Circuit Board 510 Rotational axis O mgR -O mgR Axis of Symmetry

Claims

1. A rotary encoder having a function of generating information on a rotation angle and a rotation direction of the rotating shaft from an output of a magnet fixed to a rotating shaft and a magnetic sensor disposed opposite the magnet, The rotary encoder includes a main power supply, a large Barkhausen effect generating unit, and a backup power supply that is charged by at least the large Barkhausen effect generating unit; the magnetic sensor is a TMR sensor, a magnetic sensor signal processing unit that performs AD conversion on an analog signal output from the magnetic sensor and generates digital data including two types of information, a one-revolution absolute signal and a multiple-revolution absolute signal, related to the rotation angle and the rotation direction of the rotating shaft; the magnetic sensor and the processing unit are held in an encoder housing; the TMR sensor is disposed on a printed circuit board held in the encoder housing and in a position facing the magnet; The magnet is a disk-shaped magnet having a pair of north pole region and south pole region formed thereon, The large Barkhausen effect power generating unit includes a ferromagnetic wire, a power generating coil, and a first magnetic plate and a second magnetic plate connected to both ends of the ferromagnetic wire, the first magnetic plate and the second magnetic plate extend from both ends of the ferromagnetic wire to the outside of both side surfaces of the magnet, sandwiching the magnet therebetween; A rotary encoder characterized in that the first magnetic plate and the second magnetic plate extend at a distance from each other along both side surfaces of the magnet, and the first magnetic plate and the second magnetic plate are shaped symmetrically about an axis of the rotation shaft, sandwiching the magnet.

2. In claim 1, The one-revolution absolute signal is an origin position (Z ０ The rotation angle and the rotation direction of the rotation axis relative to a rotation axis of the rotation axis, The multiple rotation absolute signal is based on the output of the TMR sensor. ０ ) containing information on the number of rotations, the direction of rotation, and the angle of rotation of the rotating shaft based on the reference.

3. In claim 1 or 2, A rotary encoder according to claim 1, wherein the two types of information, the single rotation absolute signal and the multiple rotation absolute signal, are digital data having the same maximum bit number.

4. In claim 1 or 2, the rotating shaft is a rotating shaft of a motor, A rotary encoder, characterized in that the one-revolution absolute signal, the large Barkhausen effect generating unit and the backup power supply are used for stopping the motor when the main power supply is lost.

5. In claim 1, 11. A rotary encoder according to claim 10, wherein the backup power supply comprises a capacitor that is charged by the output of the large Barkhausen effect power generation unit.

6. In claim 1, A rotary encoder characterized in that the backup power supply comprises a nickel-cadmium battery, a nickel-metal hydride battery, a lithium-ion battery, or an all-solid-state battery that is charged by the output of the large Barkhausen effect power generation unit.

7. A servo controller having a motor to be controlled, 3. A servo controller, comprising: a motor including the rotary encoder according to claim 1.

8. In claim 7, The plurality of servo controllers are connected to a common host control system that controls the plurality of servo controllers (A to N), the two types of information, i.e., the single rotation absolute signal and the multiple rotation absolute signal, are the digital data having the same maximum bit number; Each of the servo controllers (A to N) performs normal operation when the main power supply is normal, and operation stop and restart when the power supply is stopped due to a loss of the main power supply, for each of the corresponding motors, using the digital data having the same number of bits.

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