Absolute encoder with safety control function and servo controller using the same

Abstract

To provide a rotary encoder that has a safety control function and has a compact configuration.SOLUTION: A two-system absolute encoder unit includes at least one magnetic encoder unit. The magnetic encoder unit comprises: a magnet that is fixed to a rotation shaft; a magnetic sensor that is arranged opposite to the magnet; a processing unit for sensor signals that processes output from the magnetic sensor and outputs the processed output, a large Barkhausen effect power generation unit; and first and second magnetic plates. A ferromagnetic wire, a coil for power generation, and the first and second magnetic plates are arranged on the same side as the magnet relative to a printed circuit board and inside an encoder housing. The first magnetic plate and second magnetic plate extend to the outside of both side faces of the magnet while sandwiching the magnet from both ends of the ferromagnetic wire. The rotary encoder further comprises a safety control unit that, when at least one of rotary encoder units fails, copes with the failure.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a rotary encoder and a servo control device using the same, and more particularly to an absolute encoder including two independent absolute encoder units and having a safety control function, and a servo control device using 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 rotary encoder, highly accurate absolute and incremental digital signals related to the angular position are generated and output, and these signals are used, for example, to control a motor with an encoder as a servo motor in a servo control device. Rotary encoders used in servo control devices that control equipment such as industrial robots where system redundancy is important include some that are equipped with two independent rotary encoder units, so that if an abnormality occurs in one of the rotary encoders, operation will continue using the other normal rotary encoder. In addition, 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 cut off. This backup power supply uses a generator that utilizes the large Barkhausen effect, and this is used to detect multi-rotation information of the rotary encoder.

[0003] Patent Document 1 discloses an absolute encoder that is an optical rotary encoder having a disk, the disk having an M code area for generating an M code signal, a gray code area for generating a gray code signal, and an incremental area for generating an incremental signal. Patent Document 2 discloses a servo system that has a safety motion function without replacing the encoder used in the servo system with one having a safety function. That is, the servo system includes a servo motor, a control device that outputs a command signal for driving and controlling the servo motor, an encoder that detects the operation of the servo motor and outputs a feedback signal indicating the detected operation, a servo driver, and a safety unit. This safety unit monitors whether the servo motor is being controlled normally by comparing parameters (speed range, position range, etc.) preset in the safety unit with feedback from the encoder.

[0004] Patent Document 3 discloses an invention for an encoder device that has two independent rotary encoder units consisting of a first encoder having a magnetic sensor and receiving power from a power source, and a second encoder receiving power from a power generating device that utilizes the Large Barkhausen effect, and that enables the cumulative number of rotations to be updated by the second encoder even during periods when the power supply from the power source is stopped.

[0005] Patent Document 4 discloses an encoder device EC that is a multi-rotation absolute encoder that detects rotational position information including multi-rotation information indicating the number of rotations of the rotating shaft SF and angular position information indicating an angular position (rotation angle) less than one rotation. This encoder device EC includes an optical or magnetic angle detection unit that employs a composite magnetic wire having a large Barkhausen effect in its electric signal generating 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 generating 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 that guides the magnetic flux lines of one polarity part of the magnet to the other polarity part of the magnet.

[0006] Patent document 5 discloses an invention of a position detection device in which a power generation sensor 10 includes a magnetic wire FE, a coil SP (induction coil) wound around the magnetic wire FE, and a pair of magnetic flux conducting pieces (a first magnetic flux conducting piece FL1 and a second magnetic flux conducting piece FL2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication 2019-215306A1 [Patent Document 2] Patent 5367623B2 [Patent Document 3] Patent Publication 2021-21681A1 [Patent Document 4] WO2019 / 188859A1 [Patent Document 5] WO2023 / 157601A1 Summary of the Invention [Problem to be solved by the invention]

[0008] In Patent Document 1, there is no magnetic field provided for providing two independent absolute encoder units. Patent Document 2 describes the problems associated with installing two independent encoders as requiring twice the installation space compared to installing one encoder, and also that the increased number of encoders increases system costs and increases the time and cost required for initial setup of the encoders.Furthermore, it describes other problems such as that in order to achieve highly accurate detection, the initial setup of each encoder must be performed rigorously so that there is no discrepancy in the detected values ​​between the two encoders, and that if the circuits of the two encoders are identical, there is a possibility that a common failure may occur in the encoders. The encoder device described in Patent Document 3 has two magnetic rotary encoders, a first encoder and a second encoder, and two wing guard wires that face one permanent magnet in the extension direction of its axis. However, the second encoder counts four pulses per rotation of the rotating member output from the two wing guard wires, that is, it counts and outputs the number of rotations of the rotating member 15, and as a rotary encoder, it has an extremely low resolution.

[0009] The power generating device of the encoder described in Patent Document 4 has the function of generating highly accurate absolute digital signals and incremental digital signals, and also ensuring sufficient backup power. On the other hand, the electric signal generating section uses multiple permanent magnets arranged around the rotating shaft, and each permanent magnet is configured with north and south poles overlapping in the axial direction. This makes the device complex and large.

[0010] In the position detector described in Patent Document 5, a coil SP (induction coil) and a pair of magnetic flux conducting pieces (first magnetic flux conducting piece FL1 and second magnetic flux conducting piece FL2) are arranged on both sides of a first support. Patent Document 5 states that "In order to obtain a pulse voltage of sufficient power from the power generating sensor, it is necessary to apply a parallel magnetic field of a certain magnetic field strength or more to the entire magnetic wire. If the number of magnetic poles is increased without changing the size of the position detector, the magnetic poles will approach each other, causing magnetic interference with each other, making it difficult to apply a parallel magnetic field to the entire magnetic wire. It is difficult to achieve both miniaturization and high resolution." In order to solve this type, Patent Document 5 states that "the axis parallel part 42 extends along the axial direction x so as to cover the magnetic wire FE, i.e., to shield the space between the magnetic wire FE and the detection region SR." Therefore, the length in the direction of the rotation axis becomes long, and the device becomes large. There is also no disclosure of two independent absolute encoder units.

[0011] Robots, machine tools, and the like require rotary encoders with higher accuracy and resolution. For example, to enable flexible and smooth speed control so that the speed of a driven object driven by a motor can change quickly and stop slowly, position and angle data with high resolution of 20 bits or more, for example 27 bits, i.e., a rotary encoder with high accuracy and resolution, is required. Also, to increase the mounting density of equipment, a rotary encoder that is more compact and does not malfunction, even with high accuracy and high resolution, is required. In addition, in rotary encoders equipped with two rotary encoder units consisting of an optical encoder unit and a magnetic encoder unit, while the optical encoder unit has high resolution, the magnetic encoder unit is used only as an auxiliary unit, and high resolution and accuracy are often not required. One of the things to consider when increasing the resolution of a magnetic encoder and making it more compact is to prevent the output of the magnetic sensor from being affected by magnetic field interference. Also, to increase the accuracy of a rotary encoder, it is necessary for the magnetic sensor to be magnetically shielded.

[0012] One object of the present invention is to provide a rotary encoder having two independent systems, each equipped with a high-resolution absolute encoder unit, with a compact configuration that takes into consideration magnetic field interference of a magnetic encoder, and a servo control device using the same. In the present invention, a rotary encoder having a high resolution of 20 bits or more is defined as a "high-resolution rotary encoder."

[0013] Another object of the present invention is to provide a rotary encoder which employs two independent systems, each of which has a high resolution absolute encoder unit, has a safety control function, and has a high accuracy and compact configuration, and a servo control device using the same. Another object of the present invention is to provide a rotary encoder which employs two independent systems, each of which has a high-resolution absolute encoder unit, has a safety control function, and has a backup power supply, and a servo control device using the same.

[0014] When making a rotary encoder compact and highly accurate, one important thing to consider is that in many rotating electrical devices, there are many restrictions on increasing the axial length of the rotating shaft. Also, one important thing to consider when making a magnetic encoder compact is the difficulty of preventing the output of the magnetic sensor from being affected by magnetic field interference. [Means for solving the problem]

[0015] According to one aspect of the present invention, there is provided a rotary encoder including two independent absolute encoder units and a power supply unit, each of the two absolute encoder units being a high-resolution absolute encoder unit and including at least one magnetic absolute encoder unit; the magnetic absolute encoder unit includes a magnet fixed to a rotating shaft, a magnetic sensor disposed opposite the magnet, and a sensor signal processing unit that processes and outputs an output of the magnetic sensor; The power supply unit is provided with a large Barkhausen effect power generation unit, a printed circuit board on which the magnetic sensor and a processing unit for the sensor signal are mounted is held in an encoder housing having a hollow portion; The magnet fixed to the rotating shaft is a disk-shaped magnet in which a pair of N-pole regions and S-pole regions are formed in the radial direction with a boundary line passing through the center of the magnet as a boundary, and the pair of N-pole regions and S-pole regions form a single flat surface, The large Barkhausen effect power generating unit includes a ferromagnetic wire, one power generating coil, and a first magnetic plate and a second magnetic plate connected to both ends of the ferromagnetic wire, the ferromagnetic wire, the power-generating coil, the first magnetic plate, and the second magnetic plate are disposed within the encoder housing and on the same side as the magnet with respect to the printed circuit board in an axial direction of the rotation shaft, 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, the first magnetic plate and the second magnetic plate extend apart from each other along both side surfaces of the magnet, the first magnetic plate and the second magnetic plate are made of the same magnetic material, are disposed at the same height as the magnet in the axial direction of the rotation shaft, and are shaped symmetrical with respect to the magnet in the axial direction of the rotation shaft, the law of nature, The rotary encoder is further characterized by including a safety control unit that monitors the output status of the two absolute encoder units and controls the rotary encoder to stop if at least one of the absolute encoder units fails.

[0016] According to the present invention, a rotary encoder equipped with a safety control unit can be made to have two absolute encoder units and their backup power supplies, have equivalent functions, and have a short axial length of the rotating shaft, making it compact in configuration. In many rotating electrical devices, there are many restrictions on increasing the axial length of the rotating shaft, but there are relatively few restrictions on the radial space within the same radius as the housing of the rotating electrical device. The first magnetic plate and the second magnetic plate are configured to extend from both ends of the ferromagnetic wire to the outside of both sides of the magnet, sandwiching the magnet therebetween, making it possible to provide an absolute encoder unit with two independent systems, each with high resolution, while having a compact configuration.

[0017] According to another aspect of the present invention, the two-system absolute encoder units include a magnetic encoder unit including a TMR sensor and an optical encoder unit including an optical sensor, the TMR sensor is disposed on the printed circuit board at a position facing the magnet, The code pattern of the optical encoder unit is formed on a disk fixed to the rotating shaft, The disk is fixed to the rotating shaft on a side farther from the printed circuit board than the first magnetic plate and the second magnetic plate. This makes it possible to provide a rotary encoder and a servo control device using the same, which are compact in configuration but have high output, while using a single disk-shaped magnet as both a magnet for a magnetic sensor and a magnet for a large Barkhausen effect generating unit, and which generate electricity using the large Barkhausen effect as a backup power source. [Brief description of the drawings]

[0018] [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 vertical sectional view of a rotary encoder showing an example of the configuration of an optical sensor, a TMR sensor, and a power supply unit according to a first embodiment. FIG. [Diagram 3] FIG. 2 is a plan view showing an example of the configuration of a code pattern on a disk of an optical encoder. [Figure 4A] FIG. 2 is a plan view of an encoder housing, showing an example of the configuration of a large Barkhausen effect power generation unit. [Figure 4B] 3 is a diagram showing the relationship between the TMR sensor and the power supply unit shown in FIG. 2 and the magnetic flux lines of a magnet. [Diagram 5] 1 is a block diagram showing an example of the configuration of a servo controller according to a first embodiment; [Figure 6]1 is a diagram showing the rotation of a magnet and the positional relationship between the first magnetic plate and the second magnetic plate of a large Barkhausen effect generating unit. FIG. [Figure 7] FIG. 1 is a diagram conceptually explaining the function of a large Barkhausen effect power generation unit. [Figure 8] FIG. 2 is a diagram illustrating an example of a circuit configuration of a power supply unit. [Figure 9] FIG. 1 is a diagram showing the process of digitizing and absoluteizing a sensor signal of a TMR sensor. [Figure 10] 1 is a diagram showing the relationship between the rotation of a magnet and the output of a TMR sensor. [Figure 11] 4 is a flowchart showing signal processing of a TMR sensor signal. [Figure 12] 10 is a time chart showing the operation of the power supply unit, illustrating an example of the relationship between the power supply and the output signal of the rotary encoder when the main power supply goes from a normal state to a power outage. FIG. [Figure 13] 1 is a time chart showing an example of a relationship between a power supply and an output signal of a rotary encoder from a normal state of a main power supply to a power outage and recovery of the power supply; [Figure 14] 4 is a flowchart showing the operation of the safety control unit. [Figure 15] 10 is a diagram showing the relationship between two sets of magnetic sensors and a power supply unit, and magnetic flux lines of a magnet, in a rotary encoder according to a second embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The rotary encoder of the present invention can be applied to various rotating electrical machines that require absolute data of a rotating shaft, etc. Hereinafter, various embodiments of the present invention will be described. A rotary encoder according to a first embodiment of the present invention includes a circular magnet fixed to a rotating shaft, an optical encoder disk, and at least one magnetic sensor arranged on the fixed side facing the magnet, and a light receiving sensor arranged on the fixed side facing the disk, as means for generating information relating to the angular position and rotation speed of the rotating shaft.

[0020] The overall configuration and functions of a rotary encoder according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4B. FIG. 1 is a functional block diagram showing a configuration example of a rotary encoder, and FIG. 2 is a vertical cross-sectional view of the rotary encoder showing a configuration example of an optical sensor, a TMR sensor, and a power supply unit. The rotary encoder 10 includes a TMR sensor unit 11, a power supply unit 12, an optical sensor unit 13, a system control unit 14, a TMR sensor signal processing unit 15, and an optical sensor signal processing unit 17. That is, the rotary encoder 10 includes two absolute encoder units having independent and equivalent functions, each of which is made up of a magnetic encoder unit and an optical encoder unit. The TMR sensor unit 11 constituting a magnetic encoder unit has a TMR sensor 111 arranged on a printed circuit board 19 facing a magnet 110 , and a temperature sensor 113 . The magnetic encoder unit includes a flat disk-shaped magnet 110 that is magnetized with one pole each of N and S polarities, i.e., has only one pair of polarities N and S. This disk-shaped magnet has a pair of N-pole and S-pole regions formed in the radial direction with a boundary line 1101 passing through its center (see FIG. 4A), and has flat front and back surfaces and sides. This magnet 110 is, for example, a neodymium magnet, and is fixed to one end surface of the rotating shaft 510 by a non-magnetic holding member 1102, adhesive, or the like, as shown in FIG. 2. Note that a samarium-cobalt magnet or a ferrite magnet may be used instead of the neodymium magnet. The rotating shaft 510 is driven directly by a rotating electric machine such as a motor, or indirectly via a speed change mechanism, or the like.

[0021] The TMR sensor 111 is located at the axis O of the rotating shaft 510. S -O S 1, is disposed on the underside of the printed circuit board 19, that is, on the side facing the single magnet 110. The TMR sensor 111 outputs analog signals of sine waves and cosine waves as the magnet 110 rotates. The optical sensor unit 13 , which constitutes an optical encoder unit, includes a light emitting element 116 , a lens 117 , a light receiving element 118 , and a disk (code wheel) 119 fixed to a rotating shaft 510 . 3 is a plan view showing an example of the configuration of a code pattern 119A on a disk 119 of an optical encoder. An absolute code pattern is provided on the circumference of the disk 119 made of a non-magnetic material, for example glass, to indicate a binary code representing the absolute value of a high-resolution rotation angle of one rotation of the rotating shaft 510. In the example shown here, nine tracks are provided in the radial direction on the disk 119, which are coded using a Gray code. The code pattern may be binary.

[0022] The system control unit 14, the TMR sensor signal processing unit 15, and the optical sensor signal processing unit 17 are formed as an FPGA (or ASIC) 18 on a printed circuit board 19. Reference numeral 148 denotes a temperature sensor. The printed circuit board 19 is fixed to the upper end of a cylindrical encoder housing 40. The encoder housing 40 is made of, for example, non-magnetic aluminum or other materials, and is fixed to the end cover of a rotating device, such as a motor, to which the encoder is to be attached. Alternatively, something equivalent to the encoder housing 40 may be formed integrally with a member constituting the end cover or storage container of the rotating device. For convenience, this invention defines such a housing as an encoder housing. A rotating shaft 510 of the rotating device is located in a hollow portion 41 of the encoder housing 40, and a magnet 110 is fixed to the end of this 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.

[0023] The power supply unit 12 includes a main power supply 121, a large Barkhausen effect power supply 122 charged by the large Barkhausen effect power generating unit 115, and a backup power supply 123, which, together with the main power supply 121, function as power supplies that supply power to the rotary encoder 10. 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. The ferromagnetic wire 1152, one power generating coil 1154, the first magnetic plate 1156 and the second magnetic plate 1158 are positioned within the encoder housing 40 and on the same side as the magnet 110 with respect to the printed circuit board 19 in the axial direction of the rotating shaft 510. 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 On the top. This also means that one power generating coil 1154 and one magnet 110 are at the same height in the axial direction. However, this is an ideal case. In practical terms, 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, the first magnetic plate and the second magnetic plate are defined as being at the same position (height) as the magnet, including this range. Since the first magnetic plate 1156 and the second magnetic plate 1158, the one generating coil 1154, and the one magnet 110 are at the same height in the axial direction, the space within the encoder housing 40, which has the same outer diameter as the motor, can be effectively utilized, the axial length of the rotary encoder can be shortened, high accuracy of the rotary encoder can be achieved, and the rotary encoder can be configured compactly overall.

[0024] 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 set appropriately. In addition, the ends of these magnetic plates on the magnet side are open ends.

[0025] 4A is a diagram showing an example of the configuration of a large Barkhausen effect power generating unit 115. When the rotating shaft is at a position corresponding to the origin position of the motor, a boundary line 1101 between the north pole region and the south pole region of the magnet passes through the center of the flat surface of the magnet. In other words, the boundary line 1101 is aligned with the axis O of the rotating shaft 510. S -O S (See Figure 2) 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 SSince 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. In this way, the first magnetic plate 1156 and the second magnetic plate 1158 are shaped to be line-symmetrical with respect to the magnet at least near the side surface of the magnet 110. That is, as shown in Fig. 4A, 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.

[0026] 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, are tapered, for example, protruding like a pyramid or cone. This makes it easier to collect magnetic flux lines. This allows a single disk-shaped magnet to be used as both a magnet for a magnetic sensor and a magnet for a large Barkhausen effect generating unit, and allows a generator using the large Barkhausen effect as a backup power source to have a compact configuration but high output.

[0027] FIG. 4B 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 TMR sensor 111, 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 from the north pole to the south pole of the magnet keeps the TMR sensor 111 in an appropriate operable state. That is, φ1 and φ3 may be appropriately set according to 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.

[0028] In the present invention, the magnetic flux lines φ1 directed toward the TMR sensor are mainly composed of magnetic flux lines that extend from the inside of the N-pole region close to the boundary line 1101 of the magnet, axially upward (perpendicular to the surface of the magnet), and then toward the inside of the S-pole region. In contrast, the magnetic flux lines φ3 used in the large Barkhausen effect power generating unit mainly use 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 to the magnet surface, and further outward to the outside of the S-pole region and the side of the magnet. In this way, in order to suppress the influence of magnetic field interference on the magnetic flux lines φ1 that extend toward the 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. As an example, when 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 G 1 is preferably about 0.5 to 3.0 mm. Also, the gap Ga is preferably about 0.5 to 3.0 mm.

[0029] Returning to Fig. 1, the system control unit 14 includes an initial setting section 141, an encoder input / output control unit 144, a safety control unit 145, a serial / parallel signal transmission / reception unit 147, 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, the power supply unit 12, and judgment conditions for safety control, etc., according to 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.

[0030] The encoder of this embodiment has two absolute encoder units with independent but equivalent functions, and the safety control unit 145 monitors the output states of the TMR sensor 111, the optical sensor unit 13, the TMR sensor signal processing unit 15, and the optical sensor signal processing unit 17, and performs necessary processing to safely stop the operation of the rotary encoder if any of the two absolute encoder units fails. This allows the rotary encoder to function as a safety encoder. The serial / parallel signal transmitting / receiving unit 147 has the function of converting various information into parallel or serial signals and transmitting / receiving them between the rotary encoder 10 and the servo control device.

[0031] The TMR sensor signal processing unit 15 includes an analog signal processing unit 151 that processes analog signals, an AD converter 152, and a digital signal processing unit 153, and performs AD conversion on the analog signal output from the TMR sensor arranged facing the magnet 110, and generates digital data on the rotation angle and rotation direction of the rotating shaft based on this AD converted data. That is, the TMR sensor signal processing unit 15 has a function of generating, with high precision, as first digital data, two types of information on the rotation angle information of the rotating shaft, namely, a high-resolution (e.g., 27 bits / revolution) absolute signal and an incremental signal, which are quantized under predetermined conditions from the analog output of the TMR sensor 111.

[0032] The analog signal processing unit 151 receives sampling data of the analog signal (sine signal, cosine signal) of the TMR sensor 111 as time-series data, and records it in memory-1 in association with the rotation speed Nx of the rotating shaft and data from the temperature sensor 113. That is, the sampling data of the analog signal of the TMR sensor 111 is input to a 64-bit AD converter 152 (ADC-1 (sine) 1521, ADC-2 (cosine) 1522) and converted into digital values, and these converted values ​​are recorded in memory-1 (1523) as time-series data.

[0033] The TMR sensor one-rotation absolute signal generating unit 1532 of the digital signal processing unit 153 acquires the AD converted data of the rotating shaft from the memory-1, generates a one-rotation absolute signal, and records it in the memory-2. Also, the TMR sensor multiple rotation absolute signal generating unit 1533 generates a multiple rotation absolute signal, and records it in the memory-2.

[0034] The optical sensor signal processing unit 17 includes a detection processing unit 171 for detecting a light receiving sensor signal (absolute), a memory 3, and an optical sensor one-revolution absolute signal generating unit 173 and a memory 4. The detection processing unit 171 is a signal processing circuit, which encodes the light detection result of the light receiving element 118 of the optical sensor 13, and outputs a gray code representing the absolute value of the rotation angle of the rotating shaft 510. In the absolute signal generating section 173, data indicating the absolute value of the rotation angle of the rotating shaft 510 is generated based on the information of the H, L signal arrangement generated based on the Gray code data, and is recorded as time-series data in the memory 4. That is, the optical sensor signal processing unit 17 generates information of an absolute signal with high resolution (e.g., 27 bits / revolution).

[0035] Based on the output of the encoder input / output control unit 144, the TMR sensor digital data or the optical sensor digital data is converted into transmission data (BUS) for serial transmission from the rotary encoder 10, and transmitted from the serial / parallel signal transmitting / receiving unit 147 via a communication cable to an external device of the rotary encoder 10, such as a servo control device.

[0036] 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.

[0037] As shown in FIG. 2, most of the rotary encoder 10, i.e., the part except for the disk-shaped magnet 110 of the TMR sensor unit 11, the power supply unit 12, the system control unit 14, the TMR sensor signal processing unit 15, and the optical sensor signal processing unit 17, are formed or mounted on a printed circuit board 19. That is, these 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. AD converter 152 and AD converter 172 are also mounted on the printed circuit board 19 as ASICs (or FPGAs). A capacitor constituting backup power supply 123 is also mounted on the printed circuit board 19.

[0038] The system control unit 14, the TMR sensor signal processing unit 15, and the optical sensor signal processing unit 17 are functionally divided blocks, and these functions are realized by writing programs in the FPGA or ASIC digital signal processing unit, SSC interface, incremental interface, etc. The FPGA also includes a ROMRAM and at least one rewritable (overwritable) nonvolatile memory, and is connected to the CPU via a bus. As the rewritable (overwritable) nonvolatile memory, EEPROM, FRAM (registered trademark), (Ferroelectric Random Access Memory), etc. may be used. In the following description, such memory will be simply referred to as memory.

[0039] The position of one end of the boundary line 1101 between the N-pole region and the S-pole region of the magnet 110 is a specific position in the circumferential direction of the rotation shaft, that is, the origin position (Z 0 ).

[0040] 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. 6 is a diagram showing the rotation of the N-pole region and S-pole region of the magnetic field caused by 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, when the magnet 110 is in each of the rotation positions (A) to (I), the regions 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, are shown by oblique lines within one rectangle. The size of the area of ​​this facing region is related to the density of the magnetic flux lines φ3 from the magnet 110 toward 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. FIG. 6A shows the magnet 110 at the origin position (Z 0), that is, the state at a rotation angle of 0 degrees. In this state, first magnetic plate 1156 and second magnetic plate 1158 face the north pole region and south 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 north pole region and south pole region under the same conditions. From this state, when the magnet 110 is rotated 45 degrees as shown in FIG. 6B, 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 as shown in FIG. 6C, 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 and the second magnetic plate 1158 faces the S-pole region with a wider area. Furthermore, when the magnet 110 is rotated 135 degrees as shown in FIG. 6D, the area of ​​the first magnetic plate 1156 facing the N-pole region decreases, and the area of ​​the second magnetic plate 1158 facing 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 and the N-pole region and the S-pole region change. Similarly, as the magnet 110 rotates over 180 degrees as shown in Figures 6(E), (F), and (G), the areas of the first magnetic plate 1156 and the second magnetic plate 1158 facing the N-pole region and the S-pole region periodically increase and decrease significantly. This means that as the magnet 110 rotates, the density and direction of the magnetic flux lines φ3 in these magnetic plates change.

[0041] 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 1156 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. 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 to the S-pole region, i.e., from the first magnetic plate 1156 to the second magnetic plate 1158, increases as shown in Fig. 7(A) and (B). 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, and then decreases when it exceeds 90 degrees. Accordingly, as shown in Fig. 7(C), the density of the magnetic flux lines φ3 in the direction from the first magnetic plate 1156 to the second magnetic plate 1158 decreases, and further, the density of the magnetic flux lines φ3 increases in the direction from the second magnetic plate 1158 to the first magnetic plate 1156, i.e., in the reverse direction.

[0042] 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).

[0043] 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 and second magnetic plates of the large Barkhausen effect generating unit are configured to receive magnetic flux lines φ3 that are parallel or close to the magnet surface and are configured 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 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 of the large Barkhausen effect generating unit increases and decreases significantly 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 1110 extending outward on 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.

[0044] Next, the configuration of the first magnetic plate and the second magnetic plate will be described. As mentioned above, the first magnetic plate 1156 and the second magnetic plate 1158 must be shaped symmetrically with respect to the axis of symmetry on the side of the magnet 110, sandwiching the magnet, and must extend to the outside of both side surfaces of the magnet, with the first magnetic plate and the second magnetic plate extending apart along both side surfaces of the magnet. This provides a characteristic that changes periodically on both the positive and negative sides over one 360-degree rotation of the magnet, as shown in Figures 6 and 7. However, in order to obtain a predetermined output from the large Barkhausen effect generating unit 115, the characteristics shown in Figs. 6 and 7 do not need to be completely consistent on both the positive and negative sides, and some difference is acceptable. In addition, the large Barkhausen effect generating unit obtains a pulse output by a sudden change in the magnetic flux density from positive to negative or from negative to positive as the magnet rotates. Conversely, 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 positions around 90 degrees or 270 degrees shown in Fig. 7, does not contribute much to the output of the large Barkhausen effect generating unit. Therefore, it is desirable to configure the magnetic flux density of the first magnetic plate and the second magnetic plate to saturate at the positions around 90 degrees and 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, 5V. This main power supply section 1211 supplies power to an output terminal 124 via a diode 1221. The large Barkhausen effect power generation power supply 122 outputs a positive and negative pulse waveform at 180 degree intervals from the large Barkhausen effect power generation unit 115 for each rotation of the rotating shaft. This power is supplied to the output terminal 124 via a full-wave waveform circuit 1222, a smoothing circuit 1223, and a diode 1231, and supplies DC power of a predetermined voltage Vcc to the output terminal 124.

[0046] The backup power supply 123 includes a current limiting circuit 1232, a capacitor 1233, and a voltage limiting circuit 1234, and supplies DC power of a predetermined voltage Vcc to the output terminal 124. The capacitor 1233 is supplied with power from both the main power supply 121 and the large Barkhausen effect power supply 122, individually. The backup power supply 123 supplies power in place of the main power supply, and also functions as a power supply that supplies power to the rotary encoder 10 even in a power outage. The current limiting circuit 1232 controls the capacitor 1233 so that an allowable range of charge is accumulated in the capacitor 1233 by limiting the current supplied to the capacitor 1233 when the motor rotation speed is high and the amount of power generated by the large Barkhausen effect power generating unit 115 is large. For example, an electric double layer capacitor may be used for the capacitor 1233. The capacitor 1233 may be configured by connecting multiple capacitors in parallel in order to make the voltage drop gentle. The power supply line connected to the output terminal 124 of the power supply unit 12 is configured as three electrically independent lines, and power is supplied to the system control unit 14, the TMR sensor signal processing unit 15, and the optical sensor signal processing unit 17.

[0047] The rotary encoder is supplied with power from the main power supply only at startup. After startup, power is supplied to the rotary encoder from the backup power supply 123 by the large Barkhausen effect power generation power supply 122. Even when the main power supply unit 1211 is unable to supply power due to, for example, a power outage or a malfunction, power is still supplied to the rotary encoder 10 from the large Barkhausen effect power generation power supply 122, which generates power as the rotating shaft rotates. If the number of rotations of the rotating shaft decreases over time after a power outage, the output of the large Barkhausen effect power generation decreases, and it becomes impossible to supply DC power of the specified voltage Vcc to the backup power supply. 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. This allows the rotary encoder 10 to generate and record information on the rotation angle of the rotating shaft for a long period of time even if power is no longer supplied from the main power supply.

[0048] Next, the process of digitizing and converting the TMR sensor signal into an absolute value in the TMR sensor signal processing unit 15 will be described with reference to FIGS. As shown in Fig. 9A, the TMR sensor 111 outputs analog signals of one period each of 360 degrees (mechanical angle) in sine and cosine waves in response to one rotation of the rotating shaft. That is, as shown in Fig. 10, 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. The rotation angle (mechanical angle) and amplitude of these analog signals, and data on the number of rotations Nx are correlated with the temperature Ta of the temperature sensor 113, etc. by the analog signal processing unit 151 of the TMR sensor signal processing unit 15, and recorded in memory.

[0049] As shown in FIG. 9B, 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-1.

[0050] As shown in the flowchart of FIG. 11, the TMR sensor signal processing unit 15 first obtains information on the origin of the rotation axis from the initial setting values ​​(S1101). The TMR sensor signal processing unit 15 acquires information on the number of poles of the motor and the origin of the rotation shaft from the initial setting values ​​(S1101). Furthermore, AD conversion data of the TMR sensor signal (sine, cosine waves) is obtained from memory-1 (S1102). If the process is absolute conversion (YES in S1103), the TMR sensor signal processing unit 15 further calculates absolute values ​​of the rotation direction and rotation angle based on the AD conversion data and origin information (S1104), assigns memory addresses to the absolute values, and records them in memory (S1105). Then, one-revolution absolute information is generated and recorded in memory 2 as one-revolution absolute data (S1106). Furthermore, multiple-revolution absolute information is generated and recorded in memory 2 as multiple-revolution absolute data (S1107). In this way, as shown in FIG. 9C, an absolute value for each forward and reverse rotation is generated and recorded in memory-2 together with data on the number of rotations Nx, the temperature Ta, and the direction of rotation. 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. 12 is a time chart showing the operation of the power supply unit 12. That is, it is a diagram showing an example of a 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 normal, 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, data on the power supply monitoring and control unit 143 monitoring each power supply (121, 112, 123) of the power supply unit 12 is monitored (S1202). If the voltage of the main power supply 121 is normal (NO in S1203), the TMR sensor signal processing unit 15 generates an absolute signal with the same high resolution, for example, 27 bits, in single rotation mode and multi-rotation mode, based on the output of the TMR sensor. The optical sensor signal processing unit 17 generates an absolute signal with high resolution, for example, 27 bits, in single rotation mode, based on the output of the optical sensor (1204). This process is continued until the end of normal operation (S1205, S1206). If the voltage of the main power supply 121 is low in S1202 (YES in S1203), the state of the large Barkhausen effect power supply 122 is checked (S1210), and if it is normal, the power supply is switched to the large Barkhausen effect power supply (S1211). Then, an absolute signal is generated based on the output of the TMR sensor and the optical sensor (1212). This process is continued until the end of the stop process (S1213, S1214). If the power output of the large Barkhausen effect power supply 122 is absent or has decreased (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, an absolute signal is generated based on the output of the TMR sensor and the optical sensor. 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. 13 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 state of the main power supply 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] FIG. 14 is a flowchart showing the operation of the safety control unit. In the rotary encoder, the safety control unit 145 monitors the output state of the two-system absolute encoder unit consisting of a magnetic encoder unit and an optical encoder unit, here, the data of the memories 1 and 2 and the data of the memories 3 and 4. First, information on the normality judgment of the memories 1 to 4 is obtained from the initial setting unit 141 (S1401). For example, the data of the memories 1 and 3 and the data of the memories 2 and 4 per rotation are compared, and it is monitored whether they have a predetermined correspondence relationship. Alternatively, the data of the memories 1 and 2 and the data of the memories 3 and 4 per rotation are compared, and it is monitored whether they have a predetermined correspondence relationship (S1402, 1403). Alternatively, more strictly, the data of each data bit of each memory is compared, and it is monitored whether they have a predetermined correspondence relationship. Then, if the correspondence relationship of any of the data changes (NO in S1404), it is determined that one of the two systems of rotary encoder units has failed, a failure display is performed (S1430), and a process of ending the operation of the rotary encoder is performed (S1431). If it is determined that there is no malfunction, the process returns to S1402, and this process continues until the operation is terminated.

[0054] According to this embodiment, a rotary encoder having a safety function can be provided, which is provided with two absolute encoder units having independent and equivalent functions. Furthermore, a single disk-shaped magnet can be used as both a magnet for a magnetic sensor and a magnet for a large Barkhausen effect generating unit, and a power generating device using the large Barkhausen effect as a backup power source can be made compact and have high output.

[0055] Next, a rotary encoder according to a second embodiment of the present invention will be described. As the two-system absolute encoder unit of the present invention having independent equivalent functions, a two-system absolute encoder unit including two sets of magnetic sensors may be provided. For example, a combination of a first magnetic encoder unit including a TMR sensor and a second magnetic encoder unit including a GMR sensor may be employed. FIG. 15 is a diagram showing the relationship between two sets of magnetic sensors and a power supply unit, and magnetic flux lines of a magnet, in a rotary encoder according to a second embodiment of the present invention. That is, two sets of magnetic sensors are provided: a TMR sensor 111 and a GMR sensor 112. The TMR sensor 111 is installed on a printed circuit board 19 held in the encoder housing in a position facing the magnet 110, and the GMR sensor 112 is installed on the back side of the TMR sensor on the printed circuit board 19.

[0056] 15, magnetic flux lines φ1 heading toward the TMR sensor are mainly composed of magnetic flux lines that run axially upward 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, while magnetic flux lines φ2 heading toward the GMR sensor are mainly composed of magnetic flux lines that run 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, magnetic flux lines φ3 used in a large Barkhausen effect power generating unit mainly run from the outside of the magnet and the side of the magnet in a direction horizontal to the magnet surface or in a direction close to that, and then outward toward the outside of the S-pole region and the side of the magnet. The processing of the analog signals of the sine wave and cosine wave output from the GMR sensor 112 is the same as the processing of the signals output from the TMR sensor 111 described in the first embodiment. In the rotary encoder of this embodiment, one disk-shaped magnet 110 having only one pair of N and S polarities can be used as an analog signal source for two pairs of magnetic sensors and as a power generating device for the large Barkhausen effect power generating unit 115. This allows two absolute encoder units with independent and equivalent functions to be configured as a safety encoder. In addition, the power generating device using the large Barkhausen effect as a backup power source can be made compact and have high output.

[0057] The rotary encoder of the present invention may be a combination of a pair of TMR sensors, an AMR sensor and a TMR sensor, a pair of AMR sensors, or a combination of a magnetic sensor other than a TMR sensor and an optical sensor, or the like. According to the present invention, it is possible to provide a rotary encoder that is equipped with two systems of absolute encoders including a magnetic encoder and has a low-cost and compact configuration, and a servo control device using the same.

[0058] The rotary encoder of the present invention can be widely applied to various types of rotating electrical equipment, such as motors, for example, brushless motors, stepping motors, synchronous motors, induction motors, etc. The present invention can also be applied to servo control devices using these rotating electrical equipment. [Explanation of symbols]

[0059] 10 Rotary Encoder 11 TMR sensor unit 13 Optical sensor unit 110 Magnet 111 TMR sensor 115 Large Barkhausen Effect Power Unit 1156 1st magnetic plate 1158 Second magnetic plate 118 Optical Sensor 116 Light emitting element 117 Lens 118 Photodetector 119 Disc (Code Wheel) 12 Power supply unit 121 Main power supply 122 Large Barkhausen effect power source 123 Backup Power 13 Optical sensor unit 14 System Control Unit 141 Initial setting section 144 Encoder I / O control unit 145 Safety Control Unit 147 Serial / Parallel Signal Transmitter / Receiver Unit 15 TMR sensor signal processing unit 151 Analog signal processing unit for TMR sensor 152 A / D converter 153 Digital Signal Processing Unit 17 Optical 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 equipped with two independent absolute encoder units and a power supply unit, Each of the two systems of absolute encoder units is a high-resolution absolute encoder unit and includes at least one magnetic absolute encoder unit; the magnetic absolute encoder unit includes a magnet fixed to a rotating shaft, a magnetic sensor disposed opposite the magnet, and a sensor signal processing unit that processes and outputs an output of the magnetic sensor; The power supply unit is provided with a large Barkhausen effect power generation unit, a printed circuit board on which the magnetic sensor and a processing unit for the sensor signal are mounted is held in an encoder housing having a hollow portion; The magnet fixed to the rotating shaft is a disk-shaped magnet in which a pair of N-pole regions and S-pole regions are formed in the radial direction with a boundary line passing through the center of the magnet as a boundary, and the pair of N-pole regions and S-pole regions form a single flat surface, The large Barkhausen effect generating unit includes a ferromagnetic wire, a generating coil, and a first magnetic plate and a second magnetic plate connected to both ends of the ferromagnetic wire, the ferromagnetic wire, the power-generating coil, the first magnetic plate, and the second magnetic plate are disposed within the encoder housing and on the same side as the magnet with respect to the printed circuit board in an axial direction of the rotation shaft, 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; the first magnetic plate and the second magnetic plate extend apart from each other along both side surfaces of the magnet, the first magnetic plate and the second magnetic plate are made of the same magnetic material, are disposed at the same height as the magnet in the axial direction of the rotation shaft, and are shaped symmetrical with respect to the magnet in the axial direction of the rotation shaft, the law of nature, The rotary encoder further includes a safety control unit that monitors the output states of the two absolute encoder units and controls the rotary encoder to stop if at least one of the absolute encoder units fails.

2. In claim 1, The inside of the encoder housing is magnetically shielded. the two-system absolute encoder units include a magnetic absolute encoder unit including a TMR sensor and an optical absolute encoder unit including an optical sensor, the TMR sensor is disposed on the printed circuit board at a position facing the magnet, The code pattern of the optical absolute encoder unit is formed on a disk fixed to the rotating shaft, the disk is fixed to the rotating shaft on a side farther from the printed circuit board than the first magnetic plate and the second magnetic plate, The rotary encoder is characterized in that the safety control unit monitors the output state of the magnetic absolute encoder unit and the output state of the optical absolute encoder unit, and controls the rotary encoder to stop if at least one of the absolute encoder units fails.

3. In claim 1, The inside of the encoder housing is magnetically shielded. the two-system absolute encoder units include a first magnetic absolute encoder unit including a TMR sensor and a second magnetic absolute encoder unit including a GMR sensor, the TMR sensor is disposed on a printed circuit board held in the encoder housing at a position facing the magnet, and the GMR sensor is disposed on a rear side of the TMR sensor on the printed circuit board, The rotary encoder is characterized in that the safety control unit monitors the output state of the first magnetic absolute encoder unit and the output state of the second magnetic absolute encoder unit, and controls the rotary encoder to stop if at least one of the magnetic absolute encoder units fails.

4. A servo control device using a rotating electrical machine, A rotary encoder according to any one of claims 1 to 3, wherein the rotary electric device is provided with the rotary encoder according to any one of claims 1 to 3.

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