Encoder device, drive device, stage device, and robot device

Abstract

To improve reliability of detection results by suppressing power consumption even when rotation speed of a specimen is high.SOLUTION: An encoder device includes: a position detection unit that is supplied with power from a power supply and detects position information on a moving unit; a magnet that moves by movement of the moving unit; an electric signal generation unit that generates an electric signal by a change in a magnetic field due to the movement of the magnet; and a power supply unit that supplies power to the position detection unit by the electric signal. When the supply of power from the power supply is suspended, the position detection unit is supplied with power from the power supply unit regardless of a state of the electric signal and detects the position information.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an encoder device, a method for using an encoder device, a drive device, a stage device, and a robot device. [Background technology]

[0002] A known conventional encoder device is one that detects multiple rotations without a power source by driving a power-less multiple rotation detection circuit with a self-power generating means using a Wiegand wire or other magnetic power generating element (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-26397 Summary of the Invention

[0004] According to an aspect of the present invention, there is provided a position detection unit that detects position information of a moving unit, a magnet that moves with the movement of the moving unit, an electric signal generation unit that generates an electric signal in response to a change in the magnetic field caused by the movement of the magnet, and a control signal received from the position detection unit that changes the electric signal and controls the movement of the magnet based on the control signal. the a circuit section that outputs an electrical signal to the position detection section, and the position detection section includes: Based on the electrical signal generated by the electrical signal generating unit or the control signal A first input that receives the electrical signal line and, Based on the electrical signal generated by the electrical signal generating unit and the control signal A second input that is powered differently from the electrical signal line and an encoder device comprising: The present specification also describes the following aspects of the invention: According to a first aspect, there is provided an encoder device comprising a position detection unit that detects position information of a moving unit, a magnet that moves with the movement of the moving unit, an electric signal generation unit that generates an electric signal in response to a change in the magnetic field caused by the movement of the magnet, and a circuit unit that outputs the output of the electric signal generation unit, which changes with a control signal from the position detection unit, to the position detection unit.

[0005] According to a second aspect, an encoder device is provided which comprises a position detection unit which receives power from a power source and detects position information of a moving unit, a magnet which moves as the moving unit moves, an electric signal generation unit which generates an electric signal in response to a change in the magnetic field caused by the movement of the magnet, and a power supply unit which supplies power to the position detection unit using the electric signal, and which detects position information when the supply of power from the power source is cut off and the position detection unit is supplied with power from the power supply unit regardless of the state of the electric signal.

[0006] According to a third aspect, there is provided a drive device including the encoder device of the above aspect and a power supply unit that supplies power to the moving unit. According to a fourth aspect, there is provided a stage device comprising a moving object and the drive device of the third aspect that moves the moving object. According to a fifth aspect, there is provided a robot device including the drive device of the third aspect and an arm that is relatively moved by the drive device.

[0007] According to a sixth aspect, there is provided a method of using an encoder device comprising: a position detection unit that receives power from a power source and detects position information of a moving unit; a magnet that moves with the movement of the moving unit; an electric signal generation unit that generates an electric signal due to a change in the magnetic field caused by the movement of the magnet; and a power supply unit that supplies power to the position detection unit with the electric signal, wherein when the supply of power from the power source is cut off, the position detection unit is supplied with power from the power supply unit regardless of the state of the electric signal, and the position detection unit detects the position information. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an encoder device according to a first embodiment. [Figure 2] 2(A) is a perspective view showing the magnet, the electric signal generating unit, and the magnetic sensor in FIG. 1, FIG. 2(B) is a plan view showing the magnet etc. in FIG. 2(A), and FIG. 2(C) is a circuit diagram showing the magnetic sensor in FIG. 2(A). [Figure 3] (A) is a plan view showing the magnet and electric signal generating unit of FIG. 2(A), (B) and (C) are cross-sectional views of FIG. 3(A), (D) is a plan view showing a modified example, and (E) is a side view of FIG. 3(D). [Figure 4] 2 is a diagram showing the configuration of a power supply system and a multi-rotation information detection unit of the encoder device of FIG. 1. [Figure 5] 2A and 2B are diagrams illustrating the operation of the encoder device of FIG. 1 during forward rotation. [Figure 6] 10 is a flowchart showing an example of an operation during high-speed rotation. [Figure 7] 7A, 7B, 7C, 7D, and 7E are diagrams showing predetermined signals corresponding to the operations of FIG. 6, respectively. [Figure 8] FIG. 10 is a diagram illustrating the configuration of a power supply system and a multi-rotation information detection unit of an encoder device according to a second embodiment. [Figure 9] 10 is a flowchart showing an example of an operation when the power is turned off according to the second embodiment. [Figure 10] 10A, 10B, 10C, 10D, and 10E are diagrams showing predetermined signals corresponding to the operations of FIG. 9, respectively. [Figure 11] FIG. 2 is a diagram illustrating an example of a driving device. [Figure 12] FIG. 2 is a diagram illustrating an example of a stage device. [Figure 13] FIG. 1 is a diagram illustrating an example of a robot device. DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] A first embodiment will be described with reference to FIGS. 1 to 7. FIG. 1 shows an encoder device EC according to this embodiment. In FIG. 1, the encoder device EC detects rotational position information of a rotating shaft SF (moving part) of a motor M (power supply part). The rotating shaft SF is, for example, the shaft (rotor) of the motor M, but it may also be an operating shaft (output shaft) connected to the shaft of the motor M via a power transmission part such as a transmission and connected to a load. The rotational position information detected by the encoder device EC is supplied to a motor control unit MC. The motor control unit MC uses the rotational position information supplied from the encoder device EC to control the rotation of the motor M (e.g., rotational position, rotational speed, etc.). The motor control unit MC controls the rotation of the rotating shaft SF.

[0010] The encoder device EC includes a position detection system (position detection unit) 1 and a power supply system (power supply unit) 2. The position detection system 1 detects rotational position information of the rotating shaft SF. The encoder device EC is a so-called multi-rotation absolute encoder, and 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) of less than one rotation. The encoder device EC includes a multi-rotation information detection unit 3 that detects the multi-rotation information of the rotating shaft SF, and an angle detection unit 4 that detects the angular position of the rotating shaft SF.

[0011] At least a part of the position detection system 1 (e.g., angle detection unit 4) operates by receiving power from an apparatus (e.g., a drive apparatus, a stage apparatus, or a robot apparatus) in which the encoder device EC is mounted, when the power supply (e.g., main power supply) of the apparatus is turned on (normal state). At least a part of the position detection system 1 (e.g., multi-rotation information detection unit 3) operates by receiving power from a power supply system 2, when the power supply (e.g., main power supply) of the apparatus in which the encoder device EC is mounted is not turned on (emergency state, backup state, etc.). For example, when the power supply from the apparatus in which the encoder device EC is mounted is cut off, the power supply system 2 supplies power intermittently (intermittently) to at least a part of the position detection system 1 (e.g., multi-rotation information detection unit 3), and the position detection system 1 detects at least a part of the rotational position information of the rotation axis SF (e.g., multi-rotation information) when power is supplied from the power supply system 2.

[0012] The multi-rotation information detection unit 3 detects multi-rotation information, for example, using magnetism. The multi-rotation information detection unit 3 includes, for example, a magnet 11, a magnetic detection unit 12, a detection unit 13, and a storage unit 14. The magnet 11 is mounted on a disk 15 fixed to the rotation axis SF. Because the disk 15 rotates together with the rotation axis SF, the magnet 11 rotates in conjunction with the rotation axis SF. The magnet 11 is fixed to the outside of the rotation axis SF, and the relative positions of the magnet 11 and the magnetic detection unit 12 change with the rotation of the rotation axis SF. The strength and direction of the magnetic field generated by the magnet 11 on the magnetic detection unit 12 change with the rotation of the rotation axis SF. The magnetic detection unit 12 detects the magnetic field generated by the magnet 11, and the detection unit 13 detects position information of the rotation axis SF based on the results of the magnetic detection unit 12 detecting the magnetic field generated by the magnet. The storage unit 14 stores the position information detected by the detection unit 13.

[0013] The angle detection unit 4 is an optical or magnetic encoder, and detects position information (angular position information) within one rotation of the scale. For example, when it is an optical encoder, the angular position within one rotation of the rotation axis SF is detected by reading the patterning information of the scale with a light-receiving element. The patterning information of the scale is, for example, light and dark slits on the scale. The angle detection unit 4 detects the angular position information of the rotation axis SF, which is the same detection target as the multi-rotation information detection unit 3. The angle detection unit 4 includes a light-emitting element 21, a scale S, a light-receiving sensor 22, and a detection unit 23.

[0014] The scale S is provided, for example, on a disk 5 fixed to the rotation shaft SF. The scale S includes an incremental scale and an absolute scale. The scale S may be provided on the disk 15, or may be a member integrated with the disk 15. For example, the scale S may be provided on the surface of the disk 15 opposite the magnet 11. The scale S may be provided on at least one of the inside and outside of the magnet 11.

[0015] The light-emitting element 21 (illumination unit, light-emitting unit) emits light onto the scale S. The light-receiving sensor 22 (light detection unit) detects the light emitted from the light-emitting element 21 and transmitted through the scale S. In FIG. 1, the angle detection unit 4 is a transmissive type, and the light-receiving sensor 22 detects the light that has transmitted through the scale S. Note that the angle detection unit 4 may also be a reflective type. The light-receiving sensor 22 then supplies a signal indicating the detection result to the detection unit 23. The detection unit 23 uses the detection result of the light-receiving sensor 22 to detect the angular position of the rotation axis SF. For example, the detection unit 23 detects an angular position of a first resolution using the result of detecting light from an absolute scale. Furthermore, the detection unit 23 detects an angular position of a second resolution higher than the first resolution by performing an interpolation operation on the angular position of the first resolution using the result of detecting light from an incremental scale.

[0016] In this embodiment, the encoder device EC includes a signal processing unit 25. The signal processing unit 25 calculates and processes the detection result from the position detection system 1. The signal processing unit 25 includes a synthesis unit 26 and an external communication unit 27. The synthesis unit 26 acquires angular position information of the second resolution detected by the detection unit 23. The synthesis unit 26 also acquires multi-rotation information of the rotation axis SF from the storage unit 14 of the multi-rotation information detection unit 3. The synthesis unit 26 synthesizes the angular position information from the detection unit 23 and the multi-rotation information from the multi-rotation information detection unit 3 to calculate rotational position information. For example, if the detection result from the detection unit 23 is θ (rad) and the detection result from the multi-rotation information detection unit 3 is n rotations, the synthesis unit 26 calculates (2π×n+θ) (rad) as the rotational position information. The rotational position information may be a combination of multi-rotation information and angular position information of less than one rotation.

[0017] The synthesis unit 26 supplies the rotational position information to the external communication unit 27. The external communication unit 27 is communicably connected to the communication unit MCC of the motor control unit MC via a wired or wireless connection. The external communication unit 27 supplies the rotational position information in digital format to the communication unit MCC of the motor control unit MC. The motor control unit MC appropriately decodes the rotational position information from the external communication unit 27 of the angle detection unit 4. The motor control unit MC controls the rotation of the motor M by controlling the power (driving power) supplied to the motor M using the rotational position information.

[0018] The power supply system 2 includes first and second electric signal generating units 31A and 31B, a battery (cell) 32, and a switching unit 33. The electric signal generating units 31A and 31B each generate an electric signal in response to the rotation of the rotation axis SF. This electric signal includes, for example, a waveform in which the power (current, voltage) changes over time. The electric signal generating units 31A and 31B each generate electric power as an electric signal in response to, for example, a magnetic field that changes based on the rotation of the rotation axis SF. For example, the electric signal generating units 31A and 31B generate electric power in response to a change in the magnetic field formed by the magnet 11 that the multi-rotation information detecting unit 3 uses to detect the multi-rotation position of the rotation axis SF. The electric signal generating units 31A and 31B are disposed so that their angular positions relative to the magnet 11 change with the rotation of the rotation axis SF. For example, the electric signal generating units 31A and 31B generate pulse-like electric signals when the relative positions of the electric signal generating units 31A and 31B and the magnet 11 reach predetermined positions.

[0019] The battery 32 supplies at least a portion of the power consumed by the position detection system 1 based on the electrical signals generated by the electrical signal generating units 31A and 31B. The battery 32 includes a primary battery 36, such as a button battery or a dry cell battery, and a rechargeable secondary battery 37 (see FIG. 4). The secondary battery of the battery 32 is rechargeable by the electrical signals (e.g., current) generated by the electrical signal generating units 31A and 31B. The battery 32 is held in a holding unit 35. The holding unit 35 is, for example, a circuit board on which at least a portion of the position detection system 1 is provided. The holding unit 35 holds, for example, the detection unit 13, the switching unit 33, and the memory unit 14. The holding unit 35 is provided with, for example, a plurality of battery cases that can accommodate the batteries 32, as well as electrodes, wiring, and the like connected to the batteries 32.

[0020] The switching unit 33 switches between supplying and not supplying power from the battery 32 to the position detection system 1 based on the electrical signals generated by the electrical signal generating units 31A and 31B. For example, the switching unit 33 starts supplying power from the battery 32 to the position detection system 1 when the level of the electrical signals generated by the electrical signal generating units 31A and 31B becomes equal to or greater than a threshold. For example, the switching unit 33 starts supplying power from the battery 32 to the position detection system 1 when the electrical signal generating units 31A and 31B generate power equal to or greater than a threshold. Furthermore, the switching unit 33 stops supplying power from the battery 32 to the position detection system 1 when the level of the electrical signals generated by the electrical signal generating units 31A and 31B becomes less than the threshold. For example, the switching unit 33 stops supplying power from the battery 32 to the position detection system 1 when the power generated by the electrical signal generating units 31A and 31B becomes less than the threshold. For example, when a pulsed electric signal is generated in the electric signal generating units 31A and 31B, the switching unit 33 starts supplying electric power from the battery 32 to the position detection system 1 when the level (power) of this electric signal rises from a low level (hereinafter referred to as an L level) to a high level (hereinafter referred to as an H level), and stops supplying electric power from the battery 32 to the position detection system 1 after a predetermined time has elapsed since the level (power) of this electric signal changed to the L level. Also, the encoder device EC is configured to use the electric signal (pulse signal) generated by the electric signal generating units 31A and 31B as a switching signal (trigger signal) for supplying electric power from the battery 32 to the position detection system 1.

[0021] Fig. 2(A) is a perspective view showing the magnet 11, electric signal generating units 31A and 31B, and two magnetic sensors 51 and 52 that are the magnetic detection unit 12 in Fig. 1, Fig. 2(B) is a plan view of the magnet 11 and the like in Fig. 2(A) viewed from a direction parallel to the rotation axis SF, and Fig. 2(C) is a circuit diagram of the magnetic sensor 51. In Fig. 2(A) and other figures, the rotation axis SF in Fig. 1 is represented by a straight line. 2(A) and 2(B), magnet 11 is configured so that, upon rotation, the direction and strength of its magnetic field change in the axial direction (also referred to as the axial direction), which is a direction parallel to a line (axis of symmetry) passing through the center of rotation axis SF. Magnet 11 is, for example, a ring-shaped member coaxial with rotation axis SF. As an example, magnet 11 is configured from a first ring-shaped magnet consisting of N pole 16A, S pole 16B, N pole 16C, and S pole 16D, each of which is fan-shaped and has an opening angle of 90°, and arranged in order to surround rotation axis SF; and a second ring-shaped magnet consisting of S pole 17A, N pole 17B, S pole 17C, and N pole 17D, which have the same shape as N poles 16A to 16D and are attached to one side of N poles 16A to 16D, respectively. Magnet 11 is a permanent magnet that is magnetized to have four pairs of polarities along the circumferential direction (also referred to as the peripheral direction or rotational direction) around rotation axis SF, thereby generating magnetic force. The main surfaces of magnet 11, that is, the front surface (the surface opposite motor M in FIG. 1) and the back surface (the surface on the same side as motor M), are each approximately perpendicular to rotation axis SF. In other words, in magnet 11, N poles 16A to S poles 16D on the front surface side and S poles 17A to N poles 17D on the back surface side are offset by 90° (180° in phase) from each other (e.g., the positions of the N poles and S poles), and the boundaries between the N poles and S poles of N poles 16A to S poles 16D and the boundaries between the S poles and N poles of S poles 17A to N poles 17D are approximately aligned in the circumferential direction (angular position). The first annular magnet and the second annular magnet are a single magnet that is continuously integrated in the direction of movement (here, the circumferential direction, the rotational direction) or the axial direction and has multiple polarities, and may also be hollow magnets with space inside them.

[0022] For ease of explanation, counterclockwise rotation when viewed from the tip end of the rotating shaft SF (the side opposite motor M in Figure 1) is referred to as forward rotation, and clockwise rotation is referred to as reverse rotation. Furthermore, the angle of forward rotation is represented by a positive value, and the angle of reverse rotation is represented by a negative value. Note that counterclockwise rotation when viewed from the rear end of the rotating shaft SF (the side opposite motor M in Figure 1) may also be defined as forward rotation, and clockwise rotation as reverse rotation.

[0023] Here, in a coordinate system fixed to magnet 11, the angular position of the boundary between south pole 16D and north pole 16A in the circumferential direction is represented by position 11a, and the angular positions (boundaries between north pole and south pole) rotated by 90° from position 11a are represented by positions 11b, 11c, and 11d, respectively. In a first section 90° counterclockwise from position 11a, the north pole is located on the front side of magnet 11 and the south pole is located on the back side of magnet 11. In this first section, the axial direction of the magnetic field of magnet 11 is generally parallel to axial direction AD1 (see FIG. 3(C)) extending from the front side to the back side of magnet 11. In the first section, the strength of the magnetic field is greatest halfway between positions 11a and 11b and is least near positions 11a and 11b.

[0024] In the second section 90° counterclockwise from position 11b (the section where the south pole is located on the front side of magnet 11 and the north pole is located on the back side of magnet 11), the axial direction of the magnetic field of magnet 11 is generally opposite to the direction from the back side of magnet 11 to the front side (for example, the direction of axial direction AD1 (the direction of Figure 3(C))). In the second section, the magnetic field strength is maximum halfway between positions 11b and 11c and minimum near positions 11b and 11c. Similarly, in the third section 90° counterclockwise from position 11c and the fourth section 90° counterclockwise from position 11d, the axial direction of the magnetic field of magnet 11 is generally from the front side to the back side of magnet 11 and from the back side to the front side, respectively.

[0025] In this way, the axial direction of the magnetic field generated by magnet 11 is reversed sequentially at positions 11a to 11d. Magnet 11 generates an AC magnetic field in which the axial direction of the magnetic field is reversed as magnet 11 rotates with respect to a coordinate system fixed outside magnet 11. Electric signal generating units 31A and 31B are disposed on the outer surface of magnet 11 in a direction intersecting the normal direction to the main surface of magnet 11.

[0026] In this embodiment, the electric signal generating units 31A and 31B are each provided apart from the magnet 11 in a radial direction (also referred to as the radial direction) of the magnet 11 that is perpendicular to the rotation axis SF or in a direction parallel to the radial direction, without contacting the magnet 11. The first electric signal generating unit 31A includes a first magnetically sensitive part 41A, a first power generating part 42A, a first set of first magnetic bodies 45A, and a first set of second magnetic bodies 46A. Note that one of the first magnetic bodies 45A and the second magnetic bodies 46A can be omitted. The first magnetically sensitive part 41A, the first power generating part 42A, the first magnetic body 45A, and the second magnetic body 46A are fixed to the outside of the magnet 11, and their relative positions with respect to each position on the magnet 11 change as the magnet 11 rotates. For example, in Figure 2(B), position 11b of magnet 11 is located at a position 45° counterclockwise from the first electrical signal generating unit 31A, and when magnet 11 rotates one revolution in the forward direction (counterclockwise) from this state, positions 11a, 11d, 11c, and 11b pass near electrical signal generating unit 31A in this order.

[0027] The first magnetic-sensitive part 41A is a magnetic-sensitive wire such as a Wiegand wire. A large Barkhausen jump (Wiegand effect) occurs in the first magnetic-sensitive part 41A due to a change in the magnetic field caused by the rotation of the magnet 11. The first magnetic-sensitive part 41A is a cylindrical member with a rectangular projection, and its axial direction is set to the circumferential direction of the magnet 11. Hereinafter, the axial direction of the first magnetic-sensitive part 41A, i.e., the direction perpendicular to the circular (or polygonal) cross section of the first magnetic-sensitive part 41A, is also referred to as the length direction of the first magnetic-sensitive part 41A. For example, the length of the magnetic-sensitive part in a direction perpendicular to the cross section of the magnetic-sensitive part (e.g., the first magnetic-sensitive part 41A) (axial direction, length direction, longitudinal direction) is longer than the length of the magnetic-sensitive part in a direction parallel to the cross section of the magnetic-sensitive part (short direction). When an AC magnetic field is applied to the first magnetic-sensitive part 41A in its axial direction (length direction), and the AC magnetic field is reversed, a magnetic domain wall is generated extending from one end of the first magnetic-sensitive part 41A to the other end of the axial direction. In this way, the length direction (axial direction) of the magnetism-sensitive part (for example, the first magnetism-sensitive part 41A) in this embodiment is also called the direction of easy magnetization, which is the direction in which magnetization tends to orient.

[0028] The first and second magnetic bodies 45A and 46A are made of a ferromagnetic material such as iron, cobalt, or nickel. The first and second magnetic bodies 45A and 46A can also be referred to as yokes. The first magnetic body 45A is provided between the front surface of the magnet 11 and one end of the first magnetically sensitive portion 41A, and the second magnetic body 46A is provided between the back surface of the magnet 11 and the other end of the first magnetically sensitive portion 41A. The tips of the first and second magnetic bodies 45A and 46A are arranged at the same angular position in the circumferential direction on the front and back surfaces of the magnet 11. The polarities of the magnet 11 at the tips of the first and second magnetic bodies 45A and 46A are always opposite to each other. When the tip of the first magnetic body 45A is near the north pole 16A (or south pole 16B), the tip of the second magnetic body 46A is near the south pole 17A (or north pole 17B). As a result, the first and second magnetic bodies 45A and 46A guide magnetic field lines from two portions of the magnet 11 with opposite polarities (e.g., the north pole 16A and the south pole 17A) that are located at the same circumferential position of the magnet 11, in the longitudinal direction of the first magnetic-sensitive portion 41A. The magnet 11, the first magnetic body 45A, the first magnetic-sensitive portion 41A, and the second magnetic body 46A form a magnetic circuit MC1 (see FIG. 3(A)) that includes magnetic field lines that are directed in the longitudinal direction of the first magnetic-sensitive portion 41A. Note that a step (not shown) is provided on the periphery of the disk 15 in FIG. 1, and a space is secured between the periphery of the disk 15 and the back surface of the magnet 11 so that the second magnetic body 46A can be inserted.

[0029] The first power generating unit 42A is a high-density coil or the like that is wound around the first magnetism-sensitive unit 41A. Electromagnetic induction occurs in the first power generating unit 42A as a magnetic domain wall is generated in the first magnetism-sensitive unit 41A, and an induced current flows through the first power generating unit 42A. When positions 11a to 11d of the magnet 11 shown in FIG. 2(B) pass near the electric signal generating unit 31A (the tips of the magnetic bodies 45A and 46A), a pulse-like current (electric signal, electric power) is generated in the first power generating unit 42A.

[0030] The direction of the current generated in first power generating unit 42A changes depending on the direction before and after the magnetic field reversal. For example, the direction of the current generated when the magnetic field reversals from facing the front side of magnet 11 to facing the back side is opposite to the direction of the current generated when the magnetic field reversals from facing the back side of magnet 11 to facing the front side. The power (induced current) generated in first power generating unit 42A can be set, for example, by the number of turns of the high-density coil.

[0031] 2(A), the first magnetically sensitive portion 41A, the first power generating portion 42A, and the first and second magnetic bodies 45A, 46A on the first magnetically sensitive portion 41A side are housed in a case 43A. Terminals 42Aa, 42Ab are provided on the case 43A. One end and the other end of the high-density coil of the first power generating portion 42A are electrically connected to the terminals 42Aa, 42Ab, respectively. Electric power generated by the first power generating portion 42A can be extracted to the outside of the first electric signal generating unit 31A via the terminals 42Aa, 42Ab.

[0032] The second electric signal generating unit 31B is disposed at an angular position that is greater than 0° and less than 180° from the angular position at which the first electric signal generating unit 31A is disposed. The angle between the electric signal generating units 31A and 31B is selected, for example, from the range of 22.5° to 67.5°, and is approximately 45° in FIG. 2(B). The second electric signal generating unit 31B has a configuration similar to that of the first electric signal generating unit 31A. The second electric signal generating unit 31B includes a second magnetically sensitive unit 41B, a second power generating unit 42B, a second set of first magnetic bodies 45B, and a second set of second magnetic bodies 46B. The second magnetically sensitive unit 41B, the second power generating unit 42B, and the second set of first and second magnetic bodies 45B and 46B are similar to the first magnetically sensitive unit 41A, the first power generating unit 42A, and the first set of first and second magnetic bodies 45A and 46A, respectively, and therefore will not be described again. The second magnetically sensitive portion 41B, the second power generation portion 42B, and portions of the first and second magnetic bodies 45B and 46B on the second magnetically sensitive portion 41B side are housed in a case 43B. Terminals 42Ba and 42Bb are provided on the case 43B. Electric power generated by the second power generation portion 42B can be extracted to the outside of the second electric signal generating unit 31B via the terminals 42Ba and 42Bb. At least a portion of the magnetically sensitive portions (e.g., the first magnetically sensitive portion 41A, the second magnetically sensitive portion 41B) is arranged at a distance outside the magnet 11 in the radial direction of the magnet 11 or in a direction parallel thereto. For example, if the surface of the magnet 11 perpendicular to the rotation axis SF (i.e., the surface on which the multiple polarities of the magnet are arranged) is defined as one surface and the other surface, respectively, the magnetically sensitive portion is arranged at a distance outside the side of the magnet 11 parallel to the direction of movement of the magnet (or the side parallel to the axial direction of the rotation axis SF) perpendicular to one surface or the other surface of the magnet 11.

[0033] The magnetic detection unit 12 includes magnetic sensors 51 and 52. The magnetic sensor 51 is disposed at an angular position greater than 0° and less than 180° relative to the second magnetism-sensitive part 41B (second electric signal generating unit 31B) in the rotation direction of the rotation axis SF. The magnetic sensor 52 is disposed at an angular position greater than 22.5° and less than 67.5° (approximately 45° in FIG. 2(B)) relative to the magnetic sensor 51 in the rotation direction of the rotation axis SF.

[0034] As shown in FIG. 2(C), the magnetic sensor 51 includes a magnetoresistive element 56, a bias magnet (not shown) that applies a magnetic field of a certain strength to the magnetoresistive element 56, and a waveform shaping circuit (not shown) that shapes the waveform from the magnetoresistive element 56. The magnetoresistive element 56 has a full-bridge configuration in which elements 56a, 56b, 56c, and 56d are connected in series. The signal line between the elements 56a and 56c is connected to a power supply terminal 51p, and the signal line between the elements 56b and 56d is connected to a ground terminal 51g. The signal line between the elements 56a and 56b is connected to a first output terminal 51a, and the signal line between the elements 56c and 56d is connected to a second output terminal 51b. The magnetic sensor 52 has the same configuration as the magnetic sensor 51, and therefore a description thereof will be omitted.

[0035] Next, the operation of the first electric signal generating unit 31A of this embodiment will be described. In the following, the first magnetism-sensitive section 41A and the first power generating section 42A of the first electric signal generating unit 31A in FIG. 2(B) will be described as a single magnetism-sensitive member 47. The length direction of the magnetism-sensitive member 47 is the same as the length direction of the first magnetism-sensitive section 41A, and the center of the length direction of the magnetism-sensitive member 47 is the same as the center of the length direction of the first magnetism-sensitive section 41A. Note that the operation of the second electric signal generating unit 31B is similar to that of the first electric signal generating unit 31A, and therefore a description thereof will be omitted.

[0036] 3A is a plan view showing the magnet 11 and electrical signal generating unit 31A of FIG. 2A, and FIGS. 3B and 3C are cross-sectional views of the magnet 11 of FIG. 3A. In FIGS. 3A and 3B, the magnet 11 is flat along the direction of rotation around the rotation axis SF (hereinafter also referred to as the θ direction). It has multiple polarities (N poles 16A to 16D) that are different from each other in the θ direction. It also has two polarities (N pole 16A and S pole 17A, etc.) in the thickness direction (which is also the axial direction AD1 (axial direction) of the rotation axis SF in this embodiment), which is perpendicular to the θ direction. Therefore, the axial direction AD1 can also be referred to as the orientation direction (magnetization direction) of the polarity-different portions of the magnet 11 (N pole 16A and S pole 17A, etc.). The direction and strength of the magnetic field in the axial direction or orientation direction AD1 of the magnet 11 change as the magnet 11 rotates in the θ direction.

[0037] The magnetically sensitive member 47 (or magnetically sensitive portion) is disposed near the outer surface of the flat-plate magnet 11 so that its length direction is parallel to the surface (one surface or the back surface) of the magnet 11. In FIG. 3(A), if the length direction of the magnetically sensitive member 47 is defined as direction LD1, the length direction LD1 is parallel to the surface of the magnet 11. In this embodiment, the length direction LD1 of the magnetically sensitive member 47 is substantially parallel to the θ direction (circumferential direction) and substantially perpendicular to the axial direction AD1, which is the magnetization direction of the magnet 11 (for example, a specific direction in which the orientation of the magnetic poles is fixed). Furthermore, as shown in FIG. 3(C), the length direction of the magnetically sensitive member 47 is disposed so that it is substantially perpendicular to the tangential direction (here, a direction parallel to the axial direction AD1) of the magnetic field lines MF1 of the magnet 11, which pass through approximately the center of the length direction of the magnetically sensitive member 47 (for example, a position halfway along the length of the magnetically sensitive member 47 or the magnetically sensitive portions 41A, 41B). The length direction LD1 of the magnetically sensitive member 47 is arranged so as to be substantially perpendicular to the thickness direction, which is perpendicular to the θ direction. The first and second magnetic bodies 45A and 46A guide magnetic field lines from two portions of the magnet 11 with different polarities (for example, the north pole 16A and the south pole 17A) that are at the same angular position in the θ direction, in the length direction LD1 of the magnetically sensitive member 47 via one end 47a and the other end 47b of the magnetically sensitive member 47.

[0038] Magnetic field components unnecessary for pulse generation in the electric signal generating unit 31A, including magnetic field lines generated on the side surfaces of the magnet 11, are perpendicular to the longitudinal direction of the magnetic-sensitive member 47, and these unnecessary magnetic field components do not adversely affect the generation of a domain wall extending from one end of the magnetic-sensitive member 47 to the other end thereof due to a large Barkhausen jump (Wiegand effect) in the longitudinal direction of the magnetic-sensitive member 47, which is caused by the reversal of the AC magnetic field due to the rotation of the magnet 11. Therefore, even if the magnetic-sensitive member 47 is disposed near the magnet 11 and the electric signal generating unit 31A is made smaller, it is possible to efficiently generate stable, high-output pulses using the electric signal generating unit 31A due to the reversal of the axial AC magnetic field caused by the rotation of the magnet 11, without being affected by the unnecessary magnetic field components.

[0039] 4 shows the circuit configuration of the power supply system 2 and multi-rotation information detection unit 3 of the encoder device EC according to this embodiment. In Fig. 4, the power supply system 2 includes a first electric signal generating unit 31A, a rectifier stack 61, a second electric signal generating unit 31B, a rectifier stack 62, and a battery 32. The power supply system 2 also includes a regulator (smoothing unit) 63 as the switching unit 33 shown in Fig. 1.

[0040] The rectifier stack 61 is a rectifier that rectifies the current flowing from the first electrical signal generating unit 31A. A first input terminal 61a of the rectifier stack 61 is connected to a terminal 42Aa of the first electrical signal generating unit 31A. A second input terminal 61b of the rectifier stack 61 is connected to a terminal 42Ab of the first electrical signal generating unit 31A. A ground terminal 61g of the rectifier stack 61 is connected to a ground line GL that is supplied with the same potential as the signal ground SG. When the multi-rotation information detecting unit 3 is operating, the potential of the ground line GL becomes the reference potential of the circuit. An output terminal 61c of the rectifier stack 61 is connected to an input terminal of a buffer circuit 74, and an output terminal of the buffer circuit 74 is connected to a control terminal 63a of the regulator 63 and a first input terminal of an AND circuit 72.

[0041] The rectifier stack 62 is a rectifier that rectifies the current flowing from the second electrical signal generating unit 31B. A first input terminal 62a of the rectifier stack 62 is connected to the terminal 42Ba of the second electrical signal generating unit 31B. A second input terminal 62b of the rectifier stack 62 is connected to the terminal 42Bb of the second electrical signal generating unit 31B. A ground terminal 62g of the rectifier stack 62 is connected to the ground line GL. An output terminal 62c of the rectifier stack 62 is connected to the input of a buffer circuit 74. An output signal (hereinafter referred to as an enable signal) 7B of the buffer circuit 74 becomes L level when the signal at the input is below a predetermined threshold and becomes H level when the signal exceeds the threshold. A capacitor 69A is connected between the output terminals 61c, 62c of the rectifier stacks 61, 62 and the ground line GL to temporarily store the pulse signal (pulse current) generated at the output terminals 61c, 62c. Hereinafter, the pulse signal generated at the output terminals 61c, 62c will be referred to as the WW output 7A (meaning the output of the Wiegand wire). Furthermore, a discharging switching element 70 is connected between the output terminals 61c, 62c and the ground line GL, and a discharge signal 7D is supplied from the counter 67 to the control terminal of the switching element 70. If the switching element 70 is, for example, a MOS-type FET, the output terminals 61c, 62c will be connected to the drain electrode D, the source electrode S will be connected to the ground line GL, and the control terminal will be the gate electrode G. When the discharge signal 7D becomes high level, the switching element 70 becomes conductive, and the WW output 7A (the potential of the capacitor 69A) generated at the output terminals 61c, 62c rapidly drops to the reference potential. Turning the switching element 70 on to set the WW output 7A to the reference potential will hereinafter also be referred to as discharging the electrical signal generating units 31A, 31B or discharging the WW output 7A.

[0042] The regulator 63 adjusts (smooths) the power supplied from the battery 32 to the position detection system 1. The regulator 63 may include a switch 64 provided in the power supply path between the battery 32 and the position detection system 1. The regulator 63 controls the operation of the switch 64 based on the electrical signals generated by the electrical signal generating units 31A and 31B. The input terminal 63b of the regulator 63 is connected to the battery 32 via the power supply switch 38. The output terminal 63c of the regulator 63 is connected to the power supply line PL and the second input of the AND circuit 72. The ground terminal 63g of the regulator 63 is connected to the ground line GL. An input-side capacitor 69B (second capacitor) is connected between the input terminal 63b of the regulator 63 and the ground line GL, and an output-side capacitor 69C (first capacitor) is connected between the output terminal 63c and the ground line GL. The control terminal 63a of the regulator 63 is an enable terminal, and the regulator 63 maintains the potential of the output terminal 63c (the potential of the power supply line PL) at a predetermined voltage when an enable signal 7B (voltage) equal to or greater than a threshold is supplied to the control terminal 63a from the buffer circuit 74. The output voltage of the regulator 63 (the predetermined voltage) is, for example, 3V when the counter 67 is configured with a CMOS or the like. The operating voltage of the nonvolatile memory 68 of the storage unit 14 is set to, for example, the same voltage as the predetermined voltage. The predetermined voltage is a voltage required for power supply, and may be not only a constant voltage value but also a voltage that changes in stages.

[0043] The switch 64 has a first terminal 64a connected to the input terminal 63b and a second terminal 64b connected to the output terminal 63c. The regulator 63 switches between a conductive state and an insulated state between the first terminal 64a and the second terminal 64b of the switch 64 using an enable signal 7B supplied to the control terminal 63a from the buffer circuit 74 (electrical signal generating units 31A and 31B) as a control signal. For example, the switch 64 includes a switching element such as a MOS, TFT, or FET, and the first terminal 64a and the second terminal 64b are source and drain electrodes, respectively, and the gate electrode is connected to the control terminal 63a. The gate electrode of the switch 64 is charged by an electrical signal (power) generated by the electrical signal generating units 31A and 31B. When the potential of the gate electrode reaches or exceeds a threshold, the switch 64 enters a conductive state (ON state) between the source and drain electrodes. The switch 64 may be provided outside the regulator 63, for example, as an external relay.

[0044] The AND circuit 72 also outputs a signal 7E (second signal) to the delay circuit 73. The signal 7E goes high when the enable signal 7B is high and the output signal from the regulator 63 is equal to or higher than a predetermined threshold (high). The delay circuit 73 generates a reset signal 7R using the signal 7E and supplies it to the counter 67 and nonvolatile memory 68. The reset signal 7R goes high a predetermined delay time after the input signal 7E goes high, and then goes low when the signal 7E goes low. The reset signal 7R can also be considered a second signal, equivalent to the signal 7E. The counter 67 and nonvolatile memory 68 stop counting while the reset signal 7R is low. Hereinafter, the stopping of the counter 67 and nonvolatile memory 68 is also referred to as initializing or resetting the counter 67 and nonvolatile memory 68. The buffer circuit 74, AND circuit 72, and delay circuit 73 form a signal relay circuit 75.

[0045] The multiple rotation information detection unit 3 includes magnetic sensors 51 and 52 and analog comparators 65 and 66 as the magnetic detection unit 12. The magnetic detection unit 12 detects the magnetic field formed by the magnet 11 using power supplied from the battery 32. The multiple rotation information detection unit 3 also includes a counter 67 as the detection unit 13 shown in FIG. 1 and a non-volatile memory 68 as the storage unit 14. The power supply terminal 51p of the magnetic sensor 51 is connected to the power supply line PL. The ground terminal 51g of the magnetic sensor 51 is connected to the ground line GL. The output terminal 51c of the magnetic sensor 51 is connected to the input terminal 65a of the analog comparator 65. In this embodiment, the output terminal 51c of the magnetic sensor 51 outputs a voltage corresponding to the difference between the potential of the second output terminal 51b shown in FIG. 2(C) and a reference potential. The analog comparator 65 is a comparator that compares the voltage output from the magnetic sensor 51 with a predetermined voltage. The power supply terminal 65p of the analog comparator 65 is connected to the power supply line PL. The ground terminal 65g of the analog comparator 65 is connected to the ground line GL. The output terminal 65b of the analog comparator 65 is connected to a first input terminal 67a of the counter 67. The analog comparator 65 outputs a signal from the output terminal 65b that is H level when the output voltage of the magnetic sensor 51 is equal to or greater than a threshold value and L level when the output voltage is less than the threshold value. Alternatively, the analog comparator 65 may be configured to have two input terminals, and the output terminals 51a and 51b of the magnetic sensor 51 in FIG. 2(C) may be connected to these two input terminals, and the analog comparator 65 may compare the voltages at the output terminals 51a and 51b.

[0046] The magnetic sensor 52 and the analog comparator 66 have the same configuration as the magnetic sensor 51 and the analog comparator 65. The power supply terminal 52p and the ground terminal 52g of the magnetic sensor 52 are connected to the power supply line PL and the ground line GL, respectively. The output terminal 52c of the magnetic sensor 52 is connected to the input terminal 66a of the analog comparator 66. The power supply terminal 66p and the ground terminal 66g of the analog comparator 66 are connected to the power supply line PL and the ground line GL, respectively. The output terminal 66b of the analog comparator 66 is connected to a second input terminal 67b of the counter 67. The analog comparator 66 outputs a signal from the output terminal 66b that is at an H level when the output voltage of the magnetic sensor 52 is equal to or greater than a threshold value and at an L level when the output voltage is less than the threshold value.

[0047] The counter 67 counts the multiple rotation information of the rotating shaft SF using power supplied from the battery 32. The counter 67 includes, for example, a CMOS logic circuit. The counter 67 operates using power supplied via a power supply terminal 67p connected to the power supply line PL and a ground terminal 67g connected to the ground line GL. The counter 67 performs counting using the voltage supplied via the first input terminal 67a and the voltage supplied via the second input terminal 67b as detection signals. After completing the counting process and writing the data to the non-volatile memory 68, the counter 67 sets the discharge signal 7D to H level, causing the switching element 70 to conduct, thereby discharging the charge accumulated in the capacitor 69A and discharging the electrical signal generating units 31A and 31B (reducing the level of the WW output 7A). This causes the enable signal 7B to go L level, turning off the regulator 63. Note that hereinafter, discharging the electrical signal generating units 31A and 31B is also referred to as resetting the WW output 7A.

[0048] The nonvolatile memory 68 stores (performs a writing operation) at least a portion of the rotational position information (e.g., multi-rotation information) detected by the detection unit 13 using power supplied from the battery 32. The nonvolatile memory 68 stores the counting result (multi-rotation information) by the counter 67 as the rotational position information detected by the detection unit 13. A power terminal 68p and a ground terminal 68g of the nonvolatile memory 68 are connected to the power line PL and the ground line GL, respectively. The counter 67 and the nonvolatile memory 68 suspend their counting operations and write operations to the storage unit while the reset signal 7R output from the delay circuit 73 is at an L level. Furthermore, the counter 67 and the nonvolatile memory 68 perform their counting operations and write operations to or read from the storage unit while the voltage of the power line PL is equal to or higher than a predetermined threshold and the reset signal 7R is at an H level. The delay time of the reset signal 7R (the time from when the output signal 7E of the AND circuit 72 rises until the reset signal 7R rises) is set to a time that is slightly longer than the time it takes for the voltage of the power line PL to reach or exceed a predetermined threshold value and for the magnetic detection unit 12 and the counter 67 to operate correctly. The storage unit 14 in Fig. 1 includes a nonvolatile memory 68, and is capable of retaining information written while power is being supplied, even when power is not being supplied.

[0049] In this embodiment, a capacitor 69A is provided between the rectifier stacks 61, 62 and the ground line GL. The capacitor 69A is a so-called smoothing capacitor that reduces pulsation of the input signal to the buffer circuit 74. An input capacitor 69B is connected between the input terminal 63b of the regulator 63 and the ground line GL, and an output capacitor 69C is connected between the output terminal 63c of the regulator 63 and the ground line GL. The input capacitor 69B and the output capacitor 69C are smoothing capacitors that stabilize the operation of the regulator 63 (improving load response, reducing ripple, preventing oscillation, etc.). The constants of the capacitors 69B and 69C may be set, for example, so that power supply from the battery 32 to the magnetic detection unit 12 and the nonvolatile memory 68 is maintained during the period from when the magnetic detection unit 12 detects rotational position information until when the rotational position information is written to the nonvolatile memory 68. The input capacitor 69B may be omitted. The charge of the output capacitor 69C is gradually discharged by a small leakage current.

[0050] When the output capacitor 69C is empty, the regulator 63 must be charged during intermittent operation by the electrical signal generating units 31A and 31B. This causes a momentary drop in the voltage of the battery 32. After the output capacitor 69C is charged, the voltage of the battery 32 recovers and the regulator 63 operates stably. In this regard, for example, a configuration is possible in which the output of the output capacitor 69C is discharged and the reset signal 7R is set low after the counter 67 completes its counting operation. However, with this configuration, if the rotating shaft SF rotates at a high speed and the interval between regulator 63 turns-on shortens, the next WW output 7A rises and the regulator 63 turns on before the voltage of the battery 32 has fully recovered. This gradually drops the voltage of the battery 32, causing the voltage of the power line PL to remain below the threshold, potentially preventing the magnetic detection unit 12 and other components from operating accurately. Furthermore, the time it takes for the voltage of the battery 32 to recover becomes even more pronounced when the internal resistance of the battery 32 increases. In contrast to this, in this embodiment, after the counting operation of the counter 67 is completed, the WW output 7A of the electrical signal generating units 31A, 31B is discharged by the switching element 70, so that the voltage of the power supply line PL is reliably at H level even if the rotating shaft SF rotates at high speed (details will be described later).

[0051] The battery 32 also includes a primary battery 36, such as a button battery, and a rechargeable secondary battery 37. The secondary battery 37 is electrically connected to a power supply unit MCE of the motor control unit MC. The power supply unit MCE drives the motor M of FIG. 1 using power obtained from, for example, an AC power supply (not shown), and can supply a DC voltage obtained from that power to the secondary battery 37 of the battery 32. During at least a portion of the period when the power supply unit MCE of the motor control unit MC can supply power (e.g., a period when the main power supply is on), power is supplied from the power supply unit MCE to the secondary battery 37, and the secondary battery 37 is charged with this power. During the period when the power supply unit MCE of the motor control unit MC cannot supply power (e.g., a period when the main power supply is off), the supply of power from the power supply unit MCE to the secondary battery 37 is cut off.

[0052] The secondary battery 37 may also be electrically connected to a transmission path of the electric signals from the electric signal generating units 31A and 31B. In this case, the secondary battery 37 can be charged by the power of the electric signals from the electric signal generating units 31A and 31B. For example, the secondary battery 37 is electrically connected to a circuit between the rectifier stack 61 and the regulator 63. In a state where the supply of electric power from the power supply unit MCE is cut off, the secondary battery 37 can be charged by the power of the electric signals generated in the electric signal generating units 31A and 31B by the rotation of the rotating shaft SF. Note that the secondary battery 37 may also be charged by the power generated by a generator (not shown) when the rotating shaft SF is driven by the motor M and rotates.

[0053] In a state where the supply of power from an external source is cut off, the encoder device EC according to this embodiment selects whether to supply power to the position detection system 1 from the primary battery 36 or the secondary battery 37. The power supply system 2 includes a power supply switch (power supply selection unit, selection unit) 38, which switches (selects) whether to supply power to the position detection system 1 from the primary battery 36 or the secondary battery 37. A first input terminal of the power supply switch 38 is electrically connected to the positive electrode of the primary battery 36, and a second input terminal of the power supply switch 38 is electrically connected to the secondary battery 37. An output terminal of the power supply switch 38 is electrically connected to an input terminal 63b of the regulator 63.

[0054] The power supply switch 38 selects the battery that supplies power to the position detection system 1, either the primary battery 36 or the secondary battery 37, based on, for example, the remaining charge of the secondary battery 37. For example, when the remaining charge of the secondary battery 37 is equal to or greater than a threshold, the power supply switch 38 causes power to be supplied from the secondary battery 37 and prevents power from being supplied from the primary battery 36. This threshold is set based on the power consumed by the position detection system 1 and is set to, for example, a value equal to or greater than the power that should be supplied to the position detection system 1. For example, when the power consumed by the position detection system 1 can be covered by the power from the secondary battery 37, the power supply switch 38 causes power to be supplied from the secondary battery 37 and prevents power from being supplied from the primary battery 36. Furthermore, when the remaining charge of the secondary battery 37 is less than the threshold, the power supply switch 38 prevents power from being supplied from the secondary battery 37 and prevents power from being supplied from the primary battery 36. The power supply switch 38 may, for example, also function as a charger that controls the charging of the secondary battery 37, and may use information on the remaining charge of the secondary battery 37 used to control the charging to determine whether the remaining charge of the secondary battery 37 is above a threshold value.

[0055] By using the secondary battery 37 in this way, it is possible to delay the consumption of the primary battery 36. Therefore, the encoder device EC does not require maintenance (for example, replacement) of the battery 32, or the maintenance frequency is low. The battery 32 may include at least one of the primary battery 36 and the secondary battery 37. In the above-described embodiment, power is supplied alternatively from the primary battery 36 or the secondary battery 37, but power may also be supplied from both the primary battery 36 and the secondary battery 37 in parallel. For example, depending on the power consumption of each processing unit (e.g., the magnetic sensor 51, the counter 67, the non-volatile memory 68) of the position detection system 1, a processing unit to which power is supplied from the primary battery 36 and a processing unit to which power is supplied from the secondary battery 37 may be determined. The secondary battery 37 may be charged using at least one of the power supplied from the power supply unit MEC and the power of the electrical signals generated by the electrical signal generating units 31A and 31B.

[0056] Next, we will explain the normal basic operation of the power supply system 2 and the multiple rotation information detection unit 3. Figure 5 is a timing chart showing the operation of the multiple rotation information detection unit 3 when the rotation shaft SF rotates counterclockwise (forward rotation). The timing chart showing the operation of the multiple rotation information detection unit 3 when the rotation shaft SF rotates counterclockwise (reverse rotation) is the reverse of the chart in Figure 4 in time, so its explanation will be omitted.

[0057] In the "magnetic field" section of Figure 5, the solid line indicates the magnetic field at the position of the first electric signal generating unit 31A, and the dashed line indicates the magnetic field at the position of the second electric signal generating unit 31B. The "first electric signal generating unit" and the "second electric signal generating unit" respectively indicate the output of the first electric signal generating unit 31A and the output of the second electric signal generating unit 31B, with the output of a current flowing in one direction being positive (+) and the output of a current flowing in the opposite direction being negative (-). The "enable signal" refers to the enable signal 7B (potential) applied to the control terminal 63a of the regulator 63 by the electric signals generated by the electric signal generating units 31A and 31B, with the H level represented by "H" and the L level represented by "L." The "regulator output" refers to the output of the regulator 63 (the potential of the power line PL), with the H level represented by "H" and the L level represented by "L."

[0058] The "magnetic field on the first magnetic sensor" and the "magnetic field on the second magnetic sensor" in Figure 5 are the magnetic fields formed on the magnetic sensors 51 and 52. The magnetic field formed by the magnet 11 is shown by a long dashed line, the magnetic field formed by the bias magnet is shown by a short dashed line, and the composite magnetic field of these is shown by a solid line. The "first magnetic sensor" and the "second magnetic sensor" respectively indicate the output when the magnetic sensors 51 and 52 are constantly driven, with the output from the first output terminal shown by a dashed line and the output from the second output terminal shown by a solid line. The "first analog comparator" and the "second analog comparator" respectively indicate the output from the analog comparators 65 and 66. The output when the magnetic sensor and analog comparator are constantly driven is shown as "constant drive," and the output when the magnetic sensor and analog comparator are intermittently driven is shown as "intermittent drive."

[0059] When the rotation axis SF rotates counterclockwise, the first electric signal generating unit 31A outputs a current pulse flowing in the forward direction (+ of the "first electric signal generating unit") at angular positions 45° and 225°. The first electric signal generating unit 31A outputs a current pulse flowing in the reverse direction (- of the "first electric signal generating unit") at angular positions 135° and 315°. The second electric signal generating unit 31B outputs a current pulse flowing in the reverse direction (- of the "second electric signal generating unit") at angular positions 90° and 270°. The second electric signal generating unit 31B outputs a current pulse flowing in the forward direction (- of the "second electric signal generating unit") at angular positions 180° and 0° (360°). Therefore, the enable signal switches to H level at each of the angular positions 45°, 90°, 135°, 180°, 225°, 270°, 315°, and 0°. In addition, the regulator 63 supplies a predetermined voltage to the power line PL at each of the angular positions 45°, 90°, 135°, 180°, 225°, 270°, 315°, and 0° in response to the state in which the enable signal is maintained at an H level.

[0060] In this embodiment, the output of magnetic sensor 51 and the output of magnetic sensor 52 have a phase difference of 90°, and detection unit 13 detects rotational position information using this phase difference. The output of magnetic sensor 51 has a positive sine wave shape in the angular position range from 22.5° to 112.5°. Within this angular range, regulator 63 outputs power at angular positions of 45° and 90°. Magnetic sensor 51 and analog comparator 65 are driven by power supplied at angular positions of 45° and 90°. The signal output from analog comparator 65 (hereinafter referred to as the A-phase signal) is maintained at L level when no power is supplied, and becomes H level at angular positions of 45° and 90°.

[0061] The output of the magnetic sensor 52 is a positive sine wave in the angular position range of 157.5° to 247.5°. In this angular range, the regulator 63 outputs power at angular positions of 180° and 225°. The magnetic sensor 52 and the analog comparator 66 are driven by the power supplied at each of the angular positions of 180° and 225°. The signal output from the analog comparator 66 (hereinafter referred to as the B-phase signal) is maintained at L level when no power is supplied, and becomes H level at each of the angular positions of 180° and 225°.

[0062] Here, when the A-phase signal supplied to counter 67 is at H level (H) and the B-phase signal supplied to counter 67 is at L level, the set of these signal levels is represented as (H, L). In Fig. 5, the set of signal levels at an angular position of 180° is (L, H), the set of signal levels at an angular position of 225° is (H, H), and the set of signal levels at an angular position of 270° is (H, L).

[0063] When one or both of the detected A-phase signal and B-phase signal are at H level, counter 67 stores a set of signal levels in nonvolatile memory 68. When one or both of the detected A-phase signal and B-phase signal are next at H level, counter 67 reads the previous set of levels from nonvolatile memory 68 and compares the previous set of levels with the current set of levels to determine the rotation direction of rotation shaft SF.

[0064] For example, if the previous signal level pair was (H, H) and the current signal level pair is (H, L), the previous detection indicated an angular position of 225° and the current detection indicated an angular position of 270°, indicating counterclockwise rotation (forward rotation). If the current level pair is (H, L) and the previous level pair is (H, H), the counter 67 supplies an up signal to the nonvolatile memory 68 indicating that the counter should be incremented. When the nonvolatile memory 68 detects the up signal from the counter 67, it updates the stored multi-rotation information by incrementing the value by one. Furthermore, in the case of reverse rotation, the counter 67 supplies a down signal to the nonvolatile memory 68 indicating that the counter should be decremented. At this time, the nonvolatile memory 68 updates the stored multi-rotation information by decrementing the value by one. In this way, the multi-rotation information detection unit 3 according to this embodiment can detect multi-rotation information while determining the rotation direction of the rotation axis SF.

[0065] Next, an example of the operation (intermittent operation sequence) when the rotating shaft SF rotates at high speed in the encoder device EC of this embodiment will be described with reference to the flowchart in Fig. 6 and the waveform diagram in Fig. 7. When the rotating shaft SF rotates at high speed, the period TE of the enable signal in Fig. 5 becomes shorter. First, in step 102 of FIG. 6, the WW output 7A of the electrical signal generating unit 31A or 31B of FIG. 4 is generated, and the enable signal 7B of the buffer circuit 74 (see FIG. 7C) goes high. The WW output 7A is generated intermittently in short cycles as shown in FIG. 7A. Below, the operation of the WW output 7A within one cycle will be described as shown in FIGS. 7B to 7E. The signals generated by the electrical signal generating units 31A and 31B are pulsed as shown in FIG. 5. However, since the capacitor 69A is provided between the output terminals 61c and 62c and the ground line GL, the WW output 7A drops to the reference potential relatively slowly. Then, in step 104, the regulator 63 is turned on (operated) in response to the enable signal 7B, and the potential of the power line PL connected to the output terminal 63c of the regulator 63 rises as shown by the dotted line waveform (see FIG. 7B). At this time, the signal 7E of the AND circuit 72 goes high.

[0066] Furthermore, in step 106, after a predetermined time Δt has elapsed, the reset signal 7R of the delay circuit 73 goes high (see FIG. 7B). In step 108, the counter 67 and the nonvolatile memory 68 start operating. In step 110, the counter 67 writes rotation information (the above-mentioned up or down signal) to the nonvolatile memory 68. Data 7RD in FIG. 7B shows an example of a signal exchanged between the counter 67 and the nonvolatile memory 68. In step 112, the counter 67 sets the discharge signal 7D to high (see FIG. 7E). In response, the switching element 70 conducts and the WW output 7A decreases (is discharged). In step 114, the enable signal 7B of the buffer circuit 74 goes low. In step 116, the output 7E of the AND circuit 72 goes low (see FIG. 7D). This causes the regulator 63 to turn off (stop operating), and the potential of the power line PL decreases. Then, in step 118, the reset signal 7R goes low (see FIG. 7B), and the counter 67 and nonvolatile memory 68 stop operating. After that, when the WW output 7A rises, the operation returns to step 102, and the operations of steps 104 to 118 are repeated.

[0067] According to this operation, even if the pulse signals of the WW output 7A are generated intermittently at short intervals, as shown in FIG. 7A, by resetting the WW output 7A and turning off the regulator 63 each time the counter 67 finishes processing, the potential of the power line PL connected to the output terminal of the regulator 63 (dotted curve) hardly drops. This prevents the voltage of the battery 32 from dropping when the WW output 7A pulse signal is generated and the regulator 63 is turned on, ensuring that the voltage of the battery 32 is restored to its original voltage. Therefore, even when the rotating shaft SF is rotating at high speed, the supply and cut-off of power from the battery 32 to the position detection system 1 (multi-rotation information detection unit 3) can be accurately performed, reducing the power consumption of the battery 32 and enabling highly accurate determination of rotation information of the rotating shaft SF. This eliminates the need for maintenance (e.g., replacement) of the battery 32 or reduces the frequency of maintenance of the battery 32.

[0068] As described above, the encoder device EC of this embodiment includes a position detection system 1 (position detection section) that detects rotational position information of the rotation axis SF (moving section), a magnet 11 that rotates due to the rotation (movement) of the rotation axis SF, an electrical signal generating unit 31A (electrical signal generating section) that generates a WW output 7A (electrical signal) due to changes in the magnetic field caused by the rotation of the magnet 11, and a signal relay circuit 5 (circuit section) that outputs the WW output 7A or enable signal 7B (first signal) output from the electrical signal generating unit 31A to the position detection system 1 by discharging the charge accumulated in the capacitor 69A due to a discharge signal 7D (control signal) from the position detection system 1.

[0069] According to this embodiment, for example, after the position detection process in the position detection system 1 is completed, the discharge signal 7D discharges the electric signal generating unit 31A (reducing the WW output 7A) and turns off the regulator 63, thereby preventing further power consumption from the battery 32. Furthermore, because the output of the electric signal generating unit 31A is discharged, rather than the output of the regulator 63, a decrease in the output of the regulator 63 (the potential of the power supply for the position detection system 1) can be suppressed. Therefore, when the rotating shaft SF rotates at high speed, the amount of charge from the regulator 63 to the position detection system 1 each time each WW output 7A (pulse signal) is generated can be reduced, thereby reducing the amount of voltage drop in the battery 32 and shortening the time it takes for the voltage of the battery 32 to recover. Therefore, even when the rotating shaft SF is rotating at high speed, the power consumption of the battery 32 can be reduced and power can be supplied to the position detection system 1, allowing rotation information about the rotating shaft SF to be obtained with high accuracy.

[0070] This embodiment also includes an output capacitor 69C. This capacitor 69C stabilizes the operation of the regulator 63 (improving load response, etc.). Furthermore, because the output capacitor 69C is not discharged, when the rotating shaft SF rotates at high speed, the amount of charge from the regulator 63 to the output capacitor 69C each time a WW output 7A is generated can be reduced, thereby reducing the amount of voltage drop in the battery 32 and shortening the time it takes for the voltage of the battery 32 to return to normal.

[0071] Furthermore, the signal relay circuit 75 outputs a reset signal 7R (a second signal equivalent to the signal 7E) by the WW output 7A after the potential of the power supply line PL of the position detection system 1 drops to the counter 67 and nonvolatile memory 68 of the position detection system 1, and the counter 67 and nonvolatile memory 68 are initialized by the reset signal 7R (stopping the counting operation). This prevents malfunctions due to unstable signals caused by the drop in potential. Furthermore, according to this embodiment, magnetic field components unnecessary for pulse generation in the electric signal generating unit 31A, including magnetic field lines generated on the side surfaces of the magnet 11, are perpendicular to the longitudinal direction of the magnet-sensitive member 47, and these unnecessary magnetic field components do not adversely affect the generation of a domain wall extending from one end to the other in the longitudinal direction of the magnet-sensitive member 47 due to the reversal of the AC magnetic field caused by the rotation of the magnet 11. Therefore, even if the magnet-sensitive member 47 is disposed near the magnet 11 and the electric signal generating unit 31A is made smaller, it is possible to efficiently generate a high-power WW output 7A (pulse signal) with high reliability (stable output) using the electric signal generating unit 31A due to the reversal of the axial AC magnetic field caused by the rotation of the magnet 11 without being affected by the unnecessary magnetic field components.

[0072] In addition, in the encoder device EC, power is supplied from the battery 32 to the multi-rotation information detector 3 within a short time after the electric signal is generated in the electric signal generating unit 31A, causing the multi-rotation information detector 3 to dynamically operate (intermittently operate). After the detection and writing of the multi-rotation information is completed, the power supply to the multi-rotation information detector 3 is cut off, but the count value is retained because it is stored in the memory unit 14. This sequence is repeated every time a predetermined position on the magnet 11 passes near the electric signal generating unit 31A, even when the external power supply is cut off. Furthermore, the multi-rotation information stored in the memory unit 14 is read out by the motor control unit MC or the like the next time the motor M is started and used to calculate the initial position of the rotation axis SF, etc. In this encoder device EC, the battery 32 supplies at least a portion of the power consumed by the position detection system 1 in response to the electric signal generated by the electric signal generating unit 31A, thereby extending the life of the battery 32. This eliminates the need for maintenance (e.g., replacement) of the battery 32 or reduces the frequency of such maintenance. For example, if the life of the battery 32 is longer than the life of other parts of the encoder device EC, it may be possible to eliminate the need to replace the battery 32.

[0073] By using a magnetosensitive wire such as a Wiegand wire, a pulse current (electrical signal) can be output from the electric signal generating unit 31A even when the rotation speed of the magnet 11 is extremely slow. Therefore, for example, when power is not supplied to the motor M, the output of the electric signal generating unit 31A can be used as an electric signal even when the rotation speed of the rotating shaft SF (magnet 11) is extremely slow. Note that an amorphous magnetostrictive wire can also be used as the magnetosensitive wire (first magnetosensitive portion 41A). In this case, for example, the encoder device EC may be configured to full-wave rectify the electric signal (current) generated from the above-mentioned electric signal generating unit (e.g., 31A, 31B) using the above-mentioned rectifier stack (e.g., rectifier) ​​and supply the rectified power to the multi-rotation information detection unit 3 or the like.

[0074] [Second embodiment] A second embodiment will be described with reference to FIGS. 8 to 10. In FIGS. 8, 9, and 10, components corresponding to those in FIGS. 4, 6, and 7 are designated by the same reference numerals, and detailed descriptions thereof will be omitted. FIG. 8 shows an encoder device ECA according to this embodiment. In FIG. 8, an OR circuit 71 having three inputs is provided instead of the buffer circuit 74 in FIG. 4. A WW output 7A generated at output terminals 61c and 62c of rectifier stacks 61 and 62 connected to electrical signal generating units 31A and 31B is supplied to a first input of the OR circuit 71. A switching signal 7ND indicating switching between normal operation and backup operation is supplied from the power supply unit MCE of the motor control unit MC to a second input of the OR circuit 71 and a switching signal input of the counter 67. A processing completion signal 7TC indicating the completion of the counting operation is supplied from the counter 67 to a third input of the OR circuit 71. When at least one of the WW output 7A, the switching signal 7ND, and the processing completion signal 7TC goes high, the output of the OR circuit 71 goes high. When all of the WW output 7A, the switching signal 7ND, and the processing completion signal 7TC go low, the output of the OR circuit 71 goes low. The output of the OR circuit 71 is supplied as an enable signal 7B to a first input of the AND circuit 72 and to a control terminal 63a of the regulator 63. The output signal 7E of the AND circuit 72 is supplied as a reset signal 7R to the counter 67 and nonvolatile memory 68 via a delay circuit 73. The OR circuit 71, the AND circuit 72, and the delay circuit 73 constitute a signal relay circuit 75A.

[0075] As in the first embodiment, the power supply unit MCE drives the motor M shown in FIG. 1 using power obtained from, for example, an AC power supply (not shown), and supplies DC voltage obtained from that power to the secondary battery 37 of the battery 32. Furthermore, in this embodiment, as an example, during normal operation, the power supply unit MCE sets the switching signal 7ND to H level, supplies DC voltage to the secondary battery 37 of the battery 32, and power from the secondary battery 37 is supplied to the input terminal 63b of the regulator 63 via the power supply switch 38. At this time, because the enable signal 7B of the OR circuit 71 is H level, the regulator 63 is continuously on, and the potential of the power line PL is continuously H level. Therefore, the magnetic detection unit 12, the counter 67, and the nonvolatile memory 68 are continuously operating. Furthermore, because the switching signal 7ND is also supplied to the counter 67, the counter 67 can recognize that the current state is normal operation because the switching signal 7ND is H level. In this case, the counter 67 acquires the outputs of the analog comparators 65 and 66 at a predetermined sampling rate, for example, to determine rotation information for multiple rotations of the rotary shaft SF, and writes the determined information into the nonvolatile memory 68 .

[0076] In backup operation, for example, the power supply unit MCE (main power supply) is turned off, driving of the motor M (rotating shaft SF) in FIG. 1 is stopped, and the supply of power from the power supply unit MCE to the battery 32 is stopped. At this time, the power supply unit MCE sets the switching signal 7ND to L level. This allows the counter 67 to recognize that the operation has switched from normal operation to backup operation. In backup operation, to reduce the amount of power consumed by the battery 32, the regulator 63 is turned on while the WW output 7A of the electrical signal generating units 31A and 31B is above a predetermined threshold, and power is supplied to the magnetic detection unit 12, counter 67, and nonvolatile memory 68 during that period to determine rotation information about the rotating shaft SF.

[0077] However, when transitioning from normal operation to backup operation, there is a risk that power may not be supplied to the magnetic detection unit 12 and other components at the timing when the WW output 7A first rises. Therefore, in this embodiment, when the switching signal 7ND is set to L level, the counter 67 sets the processing completion signal 7TC to H level, turning on the regulator 63 and supplying power to the magnetic detection unit 12 and other components. During normal operation, the processing completion signal 7TC may always be H level, for example. After that, after rotation information is obtained, the counter 67 sets the switching signal 7ND to L level. After this, a smooth transition to the backup operation described above can be achieved. The configuration of this embodiment is otherwise the same as that of the first embodiment, and therefore a description thereof will be omitted.

[0078] Next, an example of the operation of the encoder device ECA of this embodiment when, for example, the rotating shaft SF is rotating at high speed and the power supply unit MCE (main power supply) is turned off to transition from normal operation to backup operation will be described with reference to the flowchart in Fig. 9 and the waveform diagram in Fig. 10. This operation occurs, for example, when the power supply unit MCE is turned off due to an emergency stop or the like while the rotating shaft SF is rotating at high speed with the power supply unit MCE on, and from that state the rotating shaft SF transitions from high speed rotation to a stopped state due to inertia.

[0079] First, in step 120 of FIG. 9, the power supply unit MCE (main power supply) is turned off, and the switching signal 7ND goes low (see FIG. 10A). In response to this, in step 122, the counter 67 sets the processing completion signal 7TC to high (see FIG. 10B). After this, in step 104, the enable signal 7B of the OR circuit 71 goes high, the regulator 63 operates, the potential of the power line PL goes high, and the signal 7E of the AND circuit 72 goes high. Then, in step 106, after a predetermined time has elapsed, the reset signal 7R goes high (see FIG. 10C). In step 108, the counter 67 and nonvolatile memory 68 start operating, and in step 110, the counter 67 writes the rotation information (the above-mentioned up signal or down signal) to the nonvolatile memory 68. This completes the backup of the rotation information when the power is turned off.

[0080] Then, in step 124, the counter 67 sets the processing completion signal 7TC to L level (see FIG. 10(B)), and in step 112, the counter 67 sets the discharge signal 7D to H level (see FIG. 10(E)). In response, the switching element 70 is turned on, and the WW output 7A decreases (the electric signal generating units 31A and 31B are discharged). Then, the enable signal 7B of the OR circuit 71 goes to L level. In step 116, the regulator 63 is turned off (stopped), and the output 7E of the AND circuit 72 goes to L level. Then, in step 118, the reset signal 7R goes to L level (see FIG. 10(C)), and the counter 67 and the non-volatile memory 68 stop operating. Then, the operation proceeds to step 102 of FIG. 6. Then, when the WW output 7A rises, the operations of steps 104 to 118 of FIG. 6 are repeated.

[0081] According to this operation, even if the WW output 7A rises just before or just after the power supply unit MCE (main power supply) is turned off while the rotating shaft SF is rotating at high speed, the enable signal 7B of the OR circuit 71 reliably goes high by the processing completion signal 7TC of the counter 67, the regulator 63 turns on, power is supplied to the magnetic detection unit 12, etc., rotation information of the rotating shaft SF is obtained and written to the non-volatile memory 68. Then, when the WW output 7A rises thereafter, the rotation information of the rotating shaft SF is obtained using the power of the battery 32 efficiently, as in the intermittent operation sequence of the first embodiment. Therefore, even if the rotating shaft SF is rotating at high speed, a smooth transition from normal operation to the intermittent operation sequence can be made.

[0082] As described above, the encoder device ECA according to this embodiment includes a position detection system 1 (position detection section) that receives power from the power supply section MCE and detects rotational position information of the rotation axis SF (movement section), a magnet 11 that rotates with the rotation of the rotation axis SF, an electric signal generation unit 31A (electric signal generation section) that generates a WW output 7A (electric signal) in response to a change in the magnetic field caused by the rotation of the magnet 11, and a regulator 63 (power supply section) that supplies power from a battery 32 (or the power supply section MCE) via the WW output 7A to the position detection system 1. Furthermore, when the supply of power from the power supply section MCE is cut off (when the power or the power supply section MCE is turned off), the position detection system 1 of the encoder device ECA continues to detect the rotational position information until power is supplied from the regulator 63 via the WW output 7A.

[0083] In addition, the method of using the encoder device ECA of this embodiment includes steps 122, 108, 110, and 124 in which the position detection system 1 detects its rotational position information when the power supply from the power supply unit MCE is cut off (when the power is turned off) and before power is supplied from the regulator 63 via the WW output 7A. According to this embodiment, even if the power supply unit MCE is turned off while the rotating shaft SF is rotating at high speed, the regulator 63 is turned on by, for example, the processing completion signal 7TC of the counter 67, power is supplied to the magnetic detection unit 12 of the position detection system 1, and rotation information of the rotating shaft SF is determined and stored. Therefore, even if the power supply unit MCE is turned off, after the rotation information of the rotating shaft SF at that time has been accurately determined and stored, a smooth transition can be made to the intermittent operation sequence in which the operation of the regulator 63 is controlled using the WW output 7A of the electric signal generating unit 31A. The electric signal generating unit 31A has a magnetism-sensitive part 41A whose magnetic properties change with changes in the magnetic field caused by the rotation of the magnet 11, generates a WW output 7A based on the magnetic properties of the magnetism-sensitive part 41A, and is provided with a signal relay circuit 75A (signal output part), and when the power supply part MCE is turned off, operates the regulator 63 to smooth the output of the battery 32 and supply it to the position detection system 1 (steps 120, 122, 104). The effects and the like of the magnetism-sensitive part 41A and the signal relay circuit 75A are the same as those of the first embodiment.

[0084] In this embodiment, the counter 67 outputs the processing completion signal 7TC for operating the regulator 63, so that the outputs of the electrical signal generating units 31A and 31B can be used smoothly. The element that outputs the processing completion signal 7TC does not necessarily have to be the counter 67. 3(A), the tip portions of the first and second magnetic bodies 45A, 46A of the electric signal generating unit 31A are arranged near portions of opposite polarity at the same angular position on the front surface (North pole 16A to South pole 16D) and back surface (South pole 17A to North pole 17D) of the magnet 11, thereby enabling further miniaturization of the electric signal generating unit 31A. Note that, as in the electric signal generating unit 31C of a modified example shown in FIGS. 3(D) and 3(E), the tip portion of the first magnetic body 45C on one end of the magnetically sensitive member 47 may be arranged near a portion of one polarity on the surface of the magnet 11 (e.g., North pole 16A or South pole 16B), and the tip portion of the second magnetic body 46C on the other end of the magnetically sensitive member 47 may be arranged near a portion of the opposite polarity on the surface of the magnet 11 (e.g., South pole 16D or North pole 16A). In this case, the first and second magnetic bodies 45C, 46C guide magnetic field lines from two portions of the magnet 11 with opposite polarities (e.g., the north pole 16A and the south pole 16D) that are located at different positions in the rotation direction, along the length of the magnet-sensitive member 47. In the electric signal generating unit 31C as well, a magnetic circuit MC2 is formed that runs from the magnet 11 through the first magnetic body 45C, the magnet-sensitive member 47, and the second magnetic body 46C, so that the magnet-sensitive member 47 can efficiently output stable pulses due to the reversal of the AC magnetic field caused by the rotation of the magnet 11, without being affected by unnecessary magnetic fields on the side surfaces of the magnet 11. Note that the magnet 11 may have any configuration, and the electric signal generating units 31A, 31B may also have any configuration.

[0085] In addition, although two electric signal generating units 31A and 31B are provided in the above-described embodiment, the encoder devices EC and ECA may be provided with only one electric signal generating unit 31 A. Furthermore, the encoder devices EC and ECA may be provided with three or more electric signal generating units. In addition, when multiple electrical signal generating units are provided as in the above-described embodiment, the power output from the electrical signal generating unit 31A may be used as a detection signal for detecting multi-rotation information, or may be used to supply to a detection system, etc.

[0086] In the first embodiment described above, magnet 11 is an eight-pole magnet with four poles in the circumferential direction and two poles in the thickness direction, but this configuration is not limited to this and can be modified as appropriate. For example, magnet 11 may have two or four or more poles in the circumferential direction. In the above-described embodiment, the position detection system 1 detects rotational position information of the rotation axis SF (moving part) as position information, but the position information may also detect at least one of the position, speed, and acceleration in a predetermined direction. The encoder devices EC and ECA may include a rotary encoder or a linear encoder. Furthermore, the encoder devices EC and ECA may have a power generating unit and a detecting unit provided on the rotation axis SF and a magnet 11 provided outside the moving body (e.g., the rotation axis SF), so that the relative position between the magnet and the detecting unit changes with the movement of the moving part. Furthermore, the position detection system 1 does not need to detect multi-rotation information of the rotation axis SF, and the multi-rotation information may be detected by a processing unit external to the position detection system 1.

[0087] In the above-described embodiment, the electric signal generating units 31A and 31B generate electric power (electric signals) when they are positioned in a predetermined positional relationship with the magnet 11. The position detection system 1 may use the change in the electric power (signal) generated by the electric signal generating units 31A and 31B as a detection signal to detect (count) position information (e.g., rotational position information including multi-rotation information or angular position information) of the moving part (e.g., the rotation axis SF). For example, the electric signal generating units 31A and 31B may be used as sensors (position sensors), and the position detection system 1 may detect the position information of the moving part using the electric signal generating units 31A and 31B and one or more sensors (e.g., a magnetic sensor, a light receiving sensor). Furthermore, when the number of electric signal generating units is two or more, the position detection system 1 may detect the position information using two or more electric signal generating units as sensors. For example, the position detection system 1 may use two or more electric signal generating units as sensors and detect the position information of the moving part without using a magnetic sensor or without using a light receiving sensor. Similarly to the magnetic sensor described above, the position detection system 1 may use two or more electric signal generating units as sensors and determine the rotation direction of the rotation axis SF based on two or more electric signals.

[0088] The electrical signal generating units 31A and 31B may also supply at least a portion of the power consumed by the position detection system 1. For example, the electrical signal generating units 31A and 31B may supply power to a processing unit in the position detection system 1 that consumes relatively little power. The electrical supply system 2 may not supply power to a portion of the position detection system 1. For example, the electrical supply system 2 may supply power intermittently to the detection unit 13 and not supply power to the storage unit 14. In this case, power may be supplied intermittently or continuously to the storage unit 14 from a power source, battery, or the like provided external to the electrical supply system 2. The power generating unit may generate power by a phenomenon other than the large Barkhausen jump, and may not supply power to the moving unit (e.g., the rotation axis SF) and a portion of the position detection system 1. For example, the electrical supply system 2 may supply power intermittently to the detection unit 13 and not supply power to the storage unit 14. In this case, power may be supplied intermittently or continuously to the memory unit 14 from a power source, battery, or the like provided outside the power supply system 2. The power generating unit may generate power by a phenomenon other than the large Barkhausen jump, for example, by electromagnetic induction caused by changes in the magnetic field associated with the movement of a moving unit (e.g., the rotation axis SF). The memory unit that stores the detection results of the detection unit may be provided outside the position detection system 1, or may be provided outside the encoder devices EC and ECA.

[0089] [Drive unit] An example of a drive device will be described. FIG. 11 is a diagram showing an example of the drive device MTR. In the following description, components that are the same as or equivalent to those in the above-described embodiment will be given the same reference numerals, and descriptions thereof will be omitted or simplified. This drive device MTR is a motor device including an electric motor. The drive device MTR has a rotating shaft SF, a main body (drive unit) BD that rotates and drives the rotating shaft SF, and an encoder device EC that detects rotational position information of the rotating shaft SF. Note that an encoder device ECA may be provided instead of the encoder device EC.

[0090] The rotating shaft SF has a load side end SFa and a counter-load side end SFb. The load side end SFa is connected to another power transmission mechanism such as a reducer. A scale S is fixed to the counter-load side end SFb via a fixing portion. An encoder device EC is attached to the fixed scale S. The encoder device EC is an encoder device according to any of the above-described embodiments, modifications, or combinations thereof.

[0091] In this drive device MTR, the motor control unit MC shown in Figure 1 controls the main body BD using the detection results of the encoder device EC. The drive device MTR reduces maintenance costs because there is no or little need to replace the battery of the encoder device EC. Note that the drive device MTR is not limited to a motor device, and may be another drive device having a shaft that rotates using hydraulic or pneumatic pressure.

[0092] [Stage equipment] An example of a stage device will be described. Fig. 12 shows stage device STG. This stage device STG has a configuration in which a rotary table (moving object) TB is attached to the load side end SFa of the rotation axis SF of drive device MTR shown in Fig. 11. In the following description, components that are the same as or equivalent to those in the above-mentioned embodiment will be given the same reference numerals, and description thereof will be omitted or simplified.

[0093] When the stage device STG drives the drive device MTR to rotate the rotation axis SF, this rotation is transmitted to the turntable TB. At that time, the encoder device EC detects the angular position of the rotation axis SF. Therefore, the angular position of the turntable TB can be detected by using the output from the encoder device EC. Note that a reducer or the like may be disposed between the load side end SFa of the drive device MTR and the turntable TB.

[0094] Since the stage device STG has little or no need to replace the battery of the encoder device EC, maintenance costs can be reduced. Note that the stage device STG can be applied to, for example, a rotary table provided in a machine tool such as a lathe. [Robot device] An example of a robot device will be described. FIG. 13 is a perspective view showing the robot device RBT. FIG. 13 also shows a schematic view of a portion (joint portion) of the robot device RBT. In the following description, components that are the same as or equivalent to those in the above-described embodiment will be given the same reference numerals, and description thereof will be omitted or simplified. This robot device RBT has a first arm AR1, a second arm AR2, and a joint JT. The first arm AR1 is connected to the second arm AR2 via the joint JT.

[0095] The first arm AR1 has an arm portion 101, a bearing 101a, and a bearing 101b. The second arm AR2 has an arm portion 102 and a connecting portion 102a. The connecting portion 102a is disposed between the bearing 101a and the bearing 101b at the joint JT. The connecting portion 102a is provided integrally with the rotating shaft SF2. The rotating shaft SF2 is inserted into both the bearing 101a and the bearing 101b at the joint JT. The end of the rotating shaft SF2 that is inserted into the bearing 101b passes through the bearing 101b and is connected to the reducer RG.

[0096] The reducer RG is connected to the drive unit MTR and reduces the rotation of the drive unit MTR, for example, to 1 / 100, before transmitting it to the rotating shaft SF2. Although not shown in Fig. 13, the load side end SFa of the rotating shaft SF of the drive unit MTR is connected to the reducer RG. Furthermore, the scale S of the encoder unit EC is attached to the non-load side end SFb of the rotating shaft SF of the drive unit MTR.

[0097] When the robot device RBT drives the drive unit MTR to rotate the rotation shaft SF, this rotation is transmitted to the rotation shaft SF2 via the reducer RG. The rotation of the rotation shaft SF2 rotates the connecting portion 102a integrally, causing the second arm AR2 to rotate relative to the first arm AR1. At this time, the encoder device EC detects the angular position of the rotation shaft SF, etc. Therefore, the angular position of the second arm AR2 can be detected based on the output from the encoder device EC.

[0098] Since the robot device RBT does not require or only requires a small amount of battery replacement for the encoder device EC, maintenance costs can be reduced. Note that the robot device RBT is not limited to the above configuration, and the drive unit MTR can be applied to various robot devices equipped with joints. The present specification also describes the following aspects of the invention. 1) An encoder device comprising: a position detection unit that detects position information of a moving unit; a magnet that moves with the movement of the moving unit; an electric signal generation unit that generates an electric signal in response to a change in the magnetic field caused by the movement of the magnet; and a circuit unit that outputs the output of the electric signal generation unit, which changes with a control signal from the position detection unit, to the position detection unit. 2) An encoder device according to 1, further comprising a storage unit that stores the charge output from the electrical signal generating unit, and the output of the electrical signal generating unit changes when the charge in the storage unit is discharged in response to the control signal. 3) An encoder device as described in 1 or 2, wherein the circuit unit outputs the electrical signal to the position detection unit after the potential of the position detection unit has decreased due to the output of the electrical signal generating unit, and the position detection unit is initialized by the electrical signal after the potential of the position detection unit has decreased. 4) An encoder device as described in 3, further comprising a power supply unit that supplies power to the position detection unit using the electrical signal, and the circuit unit outputs the electrical signal to the position detection unit after the potential of the position detection unit has dropped when the potential of the power supply unit is equal to or higher than a reference value. 5) The encoder device described in 4), wherein the circuit unit includes a delay unit that outputs the electrical signal to the position detection unit after the potential of the position detection unit has decreased when a predetermined time has elapsed since the potential of the power supply unit increased. 6) An encoder device according to any one of 1 to 4, wherein the position detection unit outputs the control signal to change the output of the electrical signal generation unit when the detection process of the position information of the moving unit is completed. 7) An encoder device according to any one of 1 to 6, wherein the electrical signal is output intermittently and repeatedly as the moving part moves. 8) An encoder device comprising: a position detection unit that receives power from a power source and detects position information of a moving unit; a magnet that moves with the movement of the moving unit; an electric signal generation unit that generates an electric signal in response to a change in the magnetic field caused by the movement of the magnet; and a power supply unit that supplies power to the position detection unit using the electric signal, wherein when the supply of power from the power source is cut off, the position detection unit detects the position information using the electric signal until power is supplied from the power supply unit again. 9) The encoder device according to 8, further comprising a circuit section that outputs to the position detection section an output from the electrical signal generation section that changes in response to a control signal from the position detection section when the position information is detected by the position detection section.

[0099] 10) The encoder device described in 9, wherein the circuit unit outputs the electrical signal to the position detection unit after the potential of the position detection unit has dropped due to the output from the electrical signal generating unit, and the position detection unit is initialized by the electrical signal after the potential of the position detection unit has dropped. 11) The encoder device described in 10, wherein the circuit unit is provided with a delay unit that outputs the electrical signal to the position detection unit after the potential of the position detection unit has decreased when a predetermined time has elapsed since the potential of the power supply unit increased. 12) An encoder device according to any one of 8 to 11, wherein the electrical signal is output intermittently and repeatedly as the moving part moves. 13) An encoder device described in any one of 4, 5, 7, and 8 to 12, wherein the position detection unit includes a position detection magnet and a magnetic detection unit whose relative positions change as the moving unit moves, and detects the position information based on a magnetic field formed by the position detection magnet, and the magnetic detection unit detects the magnetic field formed by the position detection magnet using power supplied from the power supply unit. 14) An encoder device described in any one of 1 to 13, wherein the position detection unit includes a scale that moves with movement of the moving unit, an irradiation unit that irradiates light onto the scale, and a light detection unit that detects light from the scale. 15) An encoder device described in any one of 1 to 7, wherein the moving part includes a rotating shaft, the magnet includes a ring-shaped or fan-shaped part, and the electrical signal generating part is arranged in multiple units along the magnet. 16) The encoder device described in 15, wherein the position detection unit includes an angle detection unit that detects angular position information within one rotation of the rotating shaft, and a multi-rotation information detection unit that detects multi-rotation information of the rotating shaft as the position information. 17) A drive device comprising the encoder device according to any one of 1 to 16 and a power supply unit that supplies power to the moving unit. 18) A stage device comprising a moving object and the drive device according to 17 that moves the moving object. 19) A robot device comprising the drive device according to 17) and an arm that is moved relatively by the drive device. 20) A method of using an encoder device comprising: a position detection unit that receives power from a power source and detects position information of a moving unit; a magnet that moves with the movement of the moving unit; an electric signal generation unit that generates an electric signal in response to a change in the magnetic field caused by the movement of the magnet; and a power supply unit that supplies power to the position detection unit using the electric signal, wherein when the supply of power from the power source is cut off, the position detection unit detects the position information using the electric signal until power is supplied from the power supply unit again. 21) The method of use according to 20, including, when the supply of power from the power source is cut off, the position detection unit determines the position information, stores it in a memory unit, and discharges the electrical signal. [Explanation of symbols]

[0100] 1...position detection system, 3...multi-rotation information detection unit, 4...angle detection unit, 11, 11A...magnet, 12...magnetic detection unit, 13...detection unit, 14...storage unit, 21...light-emitting element (illumination unit), 22...light-receiving sensor (light detection unit), 31A, 31B...electrical signal generation unit, 32...battery, 33...switching unit, 36...primary battery, 37...secondary battery, 41A, 41B...magnetically sensitive unit, 42A, 42B...power generation unit, 43A, 43B...case, 45A ...First magnetic body, 46A...Second magnetic body, 47...Magnetic sensitive member, 51, 52...Magnetic sensor, 63...Regulator, 67...Counter, 70...Switching element, 71...OR circuit, 72...AND circuit, 73...Delay circuit, 75, 75A...Signal relay circuit, EC, ECA...Encoder device, SF...Rotary axis, AR1...First arm, AR2...Second arm, MTR...Drive device, RBT...Robot device, STG...Stage device

Claims

1. a position detection unit that detects position information of the moving unit; a magnet that moves due to the movement of the moving part; an electric signal generating unit that generates an electric signal in response to a change in the magnetic field caused by the movement of the magnet; a circuit section that changes the electrical signal in response to a control signal received from the position detection section, and outputs the electrical signal based on the control signal to the position detection section; Equipped with The position detection unit a first input line that receives the electrical signal generated by the electrical signal generating unit or the electrical signal based on the control signal; a second input line to which power different from the power supplied to the electrical signal generated by the electrical signal generating unit and the electrical signal based on the control signal is supplied; Equipped with Encoder device.

2. A storage unit that stores the electric charge of the electric signal generated by the electric signal generating unit or the electric signal based on the control signal, The encoder device according to claim 1 , wherein the electric signal generated by the electric signal generating unit or the electric signal based on the control signal changes when the charge in the storage unit is discharged by the control signal.

3. The encoder device according to claim 1 , wherein the position detector is initialized by the electrical signal after the potential of the second input line has dropped.

4. a power supply unit that supplies the power to the second input line in response to the electrical signal generated by the electrical signal generation unit or the electrical signal based on the control signal; The encoder device according to claim 3 , wherein the circuit unit outputs the electrical signal to the first input line after the potential of the second input line has decreased when the potential of the power supply unit is equal to or higher than a reference value.

5. The encoder device according to claim 4 , wherein the circuit unit includes a delay unit that outputs the electrical signal to the position detection unit after the potential of the second input line has decreased when a predetermined time has elapsed since the potential of the power supply unit increased.

6. The encoder device according to claim 1 , wherein the position detector outputs the control signal to change the electrical signal when the detection process of the position information of the moving part is completed.

7. An encoder device as described in Claim 1, wherein the electrical signal generated from the electrical signal generating unit is output intermittently and repeatedly as the moving unit moves.

8. the moving part includes a rotation shaft, the magnet includes a ring-shaped or sector-shaped portion; The encoder device according to claim 1 , wherein a plurality of the electric signal generating units are arranged along the magnet.

9. the position detection unit is an angle detection unit that detects angular position information within one rotation of the rotation shaft; The encoder device according to claim 8 , further comprising: a multi-rotation information detection unit that detects multi-rotation information of the rotary shaft as the position information.

10. The encoder device according to claim 1 , wherein the power supplied to the second input line is not affected by the control signal.

11. The encoder device according to claim 4 , wherein the second input line is supplied with power from the power supply unit and is not discharged by a change in the control signal.

12. An encoder device according to any one of claims 1 to 11; a power supply unit that supplies power to the moving unit.

13. A moving object and A stage apparatus comprising: a drive apparatus according to claim 12 that moves the moving object.

14. A drive device according to claim 12; an arm that is relatively moved by the driving device.

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