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 detects multiple rotations without a power source by driving a non-power source multiple rotation detection circuit with a self-power generating means using a Wiegand wire or other magnetic generating element (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-26397 A Summary of the Invention

[0004] According to an aspect of the present invention, an encoder device is provided which includes a position detection unit which detects position information of a moving part, a magnet which moves due to the movement of the moving part, an electric signal generating unit which generates an electric signal due to a change in the magnetic field due to the movement of the magnet, and a circuit unit which changes the electric signal according to a control signal received from the position detection unit and outputs an electric signal based on the control signal to the position detection unit, wherein the position detection unit has a first input which receives the electric signal and a second input which is supplied with power different from that of the electric signal. The present specification also describes the following aspects of the invention: According to a first aspect, there is provided an encoder device including 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, there is provided 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 as the moving unit moves, an electric signal generating 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 using the electric signal, and when the power supply 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 detects the position information.

[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 for moving 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 which is supplied with power from a power source and detects position information of a moving part, a magnet which moves with the movement of the moving part, an electric signal generating unit which generates an electric signal with 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 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 method of using the position detection unit includes detecting the position information. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an encoder device according to a first embodiment. [Diagram 2] 2(A) is a perspective view showing the magnet, the electric signal generating unit, and the magnetic sensor in FIG. 1, (B) is a plan view showing the magnet etc. in FIG. 2(A), and (C) is a circuit diagram showing the magnetic sensor in FIG. 2(A). [Diagram 3]2(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 in FIG. [Diagram 5] 2A to 2C are diagrams illustrating the operation of the encoder device in FIG. 1 during forward rotation. [Figure 6] 5 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] 13 is a diagram showing the configuration of a power supply system and a multi-rotation information detection unit of an encoder device according to a second embodiment. FIG. [Figure 9] 10 is a flowchart showing an example of an operation when the power supply 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 drive device. [Figure 12] FIG. 2 is a diagram illustrating an example of a stage device. [Figure 13] FIG. 1 illustrates an example of a robot device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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, a shaft (rotor) of the motor M, but may also be an acting 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 (for example, the rotational position, the 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) 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., the angle detection unit 4) operates by receiving power from an apparatus (e.g., a drive apparatus, a stage apparatus, a robot apparatus) in which the encoder device EC is mounted, when the power source (e.g., a main power source) of the apparatus is turned on (normal state). At least a part of the position detection system 1 (e.g., the multi-rotation information detection unit 3) operates by receiving power from a power supply system 2, when the power source (e.g., a main power source) of the apparatus in which the encoder device EC is mounted is not turned on (emergency state, backup state, etc.). For example, in a state in which 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., the 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 multiple rotation information detection unit 3 detects multiple rotation information by, for example, magnetism. The multiple 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 provided on a disk 15 fixed to the rotation axis SF. Since 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 formed 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 formed by the magnet 11, and the detection unit 13 detects position information of the rotation axis SF based on the result of the magnetic detection unit 12 detecting the magnetic field formed 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, for example, 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 as the detection target of 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) irradiates light onto the scale S. The light-receiving sensor 22 (light detection unit) detects the light irradiated from the light-emitting element 21 and transmitted through the scale S. In FIG. 1, the angle detection unit 4 is a transmission type, and the light-receiving sensor 22 detects the light transmitted through the scale S. The angle detection unit 4 may be a reflection type. The light-receiving sensor 22 then supplies a signal indicating the detection result to the detection unit 23. The detection unit 23 detects the angular position of the rotation axis SF using the detection result of the light-receiving sensor 22. For example, the detection unit 23 detects the angular position of the first resolution using the result of detecting light from the absolute scale. Also, the detection unit 23 detects the angular position of the second resolution, which is 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 the 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 by 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 the angular position information of the second resolution detected by the detection unit 23. The synthesis unit 26 also acquires the 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 the rotational position information. For example, when the detection result of the detection unit 23 is θ (rad) and the detection result of 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 information that combines the multi-rotation information and the 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 wired or wireless communication. 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 power (driving power) supplied to the motor M using the rotational position information, thereby controlling the rotation of the motor M.

[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 by the rotation of the rotation axis SF. The electric signal includes, for example, a waveform in which the electric power (current, voltage) changes over time. The electric signal generating units 31A and 31B each generate electric power as an electric signal by, 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 by 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 the relative angular position with respect to the magnet 11 changes with the rotation of the rotation axis SF. The electric signal generating units 31A and 31B each generate a pulse-shaped electric signal when the relative positions of the electric signal generating units 31A and 31B and the magnet 11 reach a predetermined position.

[0019] The battery 32 supplies at least a part of the power consumed by the position detection system 1 based on the electric signals generated by the electric signal generating units 31A and 31B. The battery 32 includes a primary battery 36 such as a button battery or a dry cell, and a rechargeable secondary battery 37 (see FIG. 4). The secondary battery of the battery 32 is rechargeable by an electric signal (e.g., a current) generated by the electric 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 part 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 capable of accommodating the battery 32, and electrodes, wiring, and the like connected to the battery 32.

[0020] The switching unit 33 switches between the presence and absence of power supply from the battery 32 to the position detection system 1 based on the electric signals generated by the electric signal generating units 31A and 31B. For example, the switching unit 33 starts the supply of power from the battery 32 to the position detection system 1 when the level of the electric signals generated by the electric signal generating units 31A and 31B becomes equal to or higher than a threshold. For example, the switching unit 33 starts the supply of power from the battery 32 to the position detection system 1 when the electric signal generating units 31A and 31B generate power equal to or higher than a threshold. In addition, the switching unit 33 stops the supply of power from the battery 32 to the position detection system 1 when the level of the electric signals generated by the electric signal generating units 31A and 31B becomes lower than a threshold. For example, the switching unit 33 stops the supply of power from the battery 32 to the position detection system 1 when the power generated by the electric signal generating units 31A and 31B becomes lower than a 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 L level) to a high level (hereinafter referred to as H level), and stops supplying electric power from the battery 32 to the position detection system 1 a predetermined time after the level (power) of this electric signal changes to the L level. 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 magnet 11, electric signal generating units 31A and 31B, and two magnetic sensors 51 and 52 which are magnetic detection section 12 in Fig. 1, Fig. 2(B) is a plan view of magnet 11 etc. in Fig. 2(A) seen from a direction parallel to rotation axis SF, and Fig. 2(C) is a circuit diagram of magnetic sensor 51. In Fig. 2(A) etc., rotation axis SF in Fig. 1 is represented by a straight line. 2(A) and (B), magnet 11 is configured such that the direction and strength of the magnetic field in the axial direction (also called the axial direction), which is a direction parallel to a straight line (axis of symmetry) passing through the center of rotation axis SF, changes with rotation. Magnet 11 is, for example, a ring-shaped member coaxial with rotation axis SF. As an example, magnet 11 is configured with a first ring-shaped magnet consisting of N pole 16A, S pole 16B, N pole 16C, and S pole 16D, each of which is a sector shape with 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 pole 16A to S pole 16D and are attached to one side of N pole 16A to S pole 16D, respectively. Magnet 11 is a permanent magnet that generates magnetic force by being magnetized to have four pairs of polarities along the circumferential direction (also referred to as the peripheral direction or rotation direction) around rotation axis SF. 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) in angle (e.g., the positions of the N poles and S poles relative to each other), 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 position (angular position). The first and second annular magnets are a single magnet that is integrated continuously in the direction of movement (here, the circumferential direction, the rotational direction) or the axial direction and has multiple polarities, and may be hollow magnets with space inside the magnets.

[0022] For ease of explanation, counterclockwise rotation when viewed from the tip end side of the rotating shaft SF (the opposite side to motor M in FIG. 1) is called forward rotation, and clockwise rotation is called reverse rotation. Also, the angle of forward rotation is expressed as a positive value, and the angle of reverse rotation is expressed as a negative value. Note that counterclockwise rotation when viewed from the rear end side of the rotating shaft SF (the side of motor M in FIG. 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 S pole 16D and N pole 16A in the circumferential direction is represented by position 11a, and the angular positions (boundaries between the N pole and S pole) sequentially rotated by 90° from position 11a are represented by positions 11b, 11c, and 11d, respectively. In a first section of 90° counterclockwise from position 11a, a north pole is arranged on the front side of magnet 11, and a south pole is arranged 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 an axial direction AD1 (see FIG. 3(C)) that runs from the front side to the back side of magnet 11. In the first section, the strength of the magnetic field is maximum halfway between positions 11a and 11b, and minimum near positions 11a and 11b.

[0024] In the second section 90° counterclockwise from position 11b (the section where the S pole is arranged on the front side of magnet 11 and the N pole is arranged on the back side of magnet 11), the axial direction of the magnetic field of magnet 11 is generally from the back side to the front side of magnet 11 (for example, opposite to the 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 is minimum in the vicinity of positions 11b and 11c. Similarly, in the third section 90° counterclockwise from position 11c, and in 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 with the normal direction of the main surface of magnet 11.

[0026] In this embodiment, the electric signal generating units 31A and 31B are provided in a radial direction (also called a radial direction) of the magnet 11 perpendicular to the rotation axis SF or in a direction parallel to the radial direction, and are not in contact with the magnet 11. The first electric signal generating unit 31A includes a first magnetically sensitive section 41A, a first power generating section 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 body 45A and the second magnetic body 46A can be omitted. The first magnetically sensitive section 41A, the first power generating section 42A, the first magnetic body 45A, and the second magnetic body 46A are fixed to the outside of the magnet 11, and the relative positions with respect to each position on the magnet 11 change with the rotation of the magnet 11. For example, in FIG. 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 once in the forward direction (counterclockwise) from this state, positions 11a, 11d, 11c, and 11b pass near electrical signal generating unit 31A in that order.

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

[0028] The first and second magnetic bodies 45A, 46A are made of a ferromagnetic material such as iron, cobalt, or nickel. The first and second magnetic bodies 45A, 46A can also be called a yoke. 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, 46A are arranged at the same angular positions 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, 46A are always opposite to each other, and when the tip of the first magnetic body 45A is near the N pole 16A (or the S pole 16B), the tip of the second magnetic body 46A is near the S pole 17A (or the N pole 17B). Therefore, the first and second magnetic bodies 45A, 46A guide magnetic field lines from two parts of the magnet 11 with different polarities (e.g., the north pole 16A and the south pole 17A) that are at the same circumferential position of the magnet 11 in the length direction of the first magnetically sensitive portion 41A. The magnet 11, the first magnetic body 45A, the first magnetically sensitive portion 41A, and the second magnetic body 46A form a magnetic circuit MC1 (see FIG. 3(A)) including magnetic field lines that run in the length direction of the first magnetically 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 provided between the periphery of the disk 15 and the back surface of the magnet 11 to allow the second magnetic body 46A to be inserted.

[0029] The first power generating unit 42A is a high-density coil wound around the first magnetically sensitive unit 41A. Electromagnetic induction occurs in the first power generating unit 42A due to the generation of a magnetic domain wall in the first magnetically sensitive unit 41A, and an induced current flows through the first power generating unit 42A. When the 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 (electrical signal, power) is generated in the first power generating unit 42A.

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

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

[0032] The second electric signal generating unit 31B is disposed at an angle position that is greater than 0° and smaller than 180° from the angle position where 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 a 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 section 41B, a second power generating section 42B, a second set of first magnetic bodies 45B, and a second set of second magnetic bodies 46B. The second magnetically sensitive section 41B, the second power generating section 42B, and the second set of first and second magnetic bodies 45B and 46B are similar to the first magnetically sensitive section 41A, the first power generating section 42A, and the first set of first and second magnetic bodies 45A and 46A, respectively, and their description will be omitted. The second magnetically sensitive section 41B, the second power generating section 42B, and the first and second magnetic bodies 45B and 46B on the second magnetically sensitive section 41B side are housed in a case 43B. The case 43B is provided with terminals 42Ba and 42Bb. Electric power generated by the second power generating section 42B can be taken out of the second electric signal generating unit 31B via the terminals 42Ba and 42Bb. At least a part of the magnetically sensitive section (e.g., the first magnetically sensitive section 41A, the second magnetically sensitive section 41B) is disposed at a distance outside the magnet 11 in the radial direction of the magnet 11 or in a direction parallel thereto. For example, when the surface of the magnet 11 perpendicular to the rotation axis SF (i.e., the surface on which the magnet has a plurality of polarities arranged) is defined as one surface and the other surface, respectively, the magnetically sensitive section is disposed at a distance outside the side surface of the magnet 11 (or the side surface parallel to the axial direction of the rotation axis SF) perpendicular to the one surface or the other surface of the magnet 11 along the movement direction of the magnet.

[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 magnetically sensitive unit 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. 2C, the magnetic sensor 51 includes a magnetic resistance element 56, a bias magnet (not shown) that applies a magnetic field of a certain strength to the magnetic resistance element 56, and a waveform shaping circuit (not shown) that shapes the waveform from the magnetic resistance element 56. The magnetic resistance element 56 has a full bridge shape 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 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 the description thereof will be omitted.

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

[0037] Moreover, the magnetically sensitive member 47 (or the magnetically sensitive portion) is disposed near the outer surface of the magnet 11 so that its length direction is parallel to the surface (one surface or the back surface) of the flat magnet 11. In FIG. 3(A), if the length direction of the magnetically sensitive member 47 is a 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 approximately parallel to the θ direction (circumferential direction) and is approximately perpendicular to the axial direction (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 as to be approximately perpendicular to the tangential direction (here, a direction parallel to the axial direction AD1) of the magnetic field lines MF1 of the magnet 11 that pass through the approximate center of the length direction of the magnetically sensitive member 47 (for example, a position halfway along the length direction of the magnetically sensitive member 47 or the magnetically sensitive portions 41A and 41B). The length direction LD1 of the magnetically sensitive member 47 is disposed so as to be substantially perpendicular to the thickness direction 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 (e.g., the N pole 16A and the S pole 17A) that are at the same angular position in the θ direction to 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 surface of the magnet 11, are perpendicular to the longitudinal direction of the magnetically sensitive member 47, and the unnecessary magnetic field components do not adversely affect the generation of a magnetic domain wall from one end of the magnetically sensitive member 47 to the other end thereof due to a large Barkhausen jump (Wiegand effect) in the longitudinal direction of the magnetically sensitive member 47, which is generated by the reversal of the AC magnetic field due to the rotation of the magnet 11. Therefore, even if the magnetically 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] Fig. 4 shows a circuit configuration of the power supply system 2 and the 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 electric signal generating unit 31A. The first input terminal 61a of the rectifier stack 61 is connected to the terminal 42Aa of the first electric signal generating unit 31A. The second input terminal 61b of the rectifier stack 61 is connected to the terminal 42Ab of the first electric signal generating unit 31A. The ground terminal 61g of the rectifier stack 61 is connected to a ground line GL to which the same potential as the signal ground SG is supplied. When the multi-rotation information detection unit 3 is in operation, the potential of the ground line GL becomes the reference potential of the circuit. The output terminal 61c of the rectifier stack 61 is connected to the input part of the buffer circuit 74, and the output part of the buffer circuit 74 is connected to the control terminal 63a of the regulator 63 and the first input part of the AND circuit 72.

[0041] The rectifier stack 62 is a rectifier that rectifies the current flowing from the second electric signal generating unit 31B. The first input terminal 62a of the rectifier stack 62 is connected to the terminal 42Ba of the second electric signal generating unit 31B. The second input terminal 62b of the rectifier stack 62 is connected to the terminal 42Bb of the second electric signal generating unit 31B. The ground terminal 62g of the rectifier stack 62 is connected to the ground line GL. The output terminal 62c of the rectifier stack 62 is connected to the input part of the buffer circuit 74. The output signal (hereinafter referred to as an enable signal) 7B of the buffer circuit 74 is a signal that becomes L level when the signal of the input part is equal to or lower than a predetermined threshold value, and becomes H level when the signal exceeds the threshold value. A capacitor 69A for temporarily storing the pulse signal (pulse current) generated at the output terminals 61c, 62c of the rectifier stacks 61, 62 is connected between the output terminals 61c, 62c of the rectifier stacks 61, 62 and the ground line GL. Hereinafter, the pulse signal generated at the output terminals 61c, 62c is 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. When the switching element 70 is, for example, a MOS type FET, the output terminals 61c, 62c are connected to the drain electrode D, the source electrode S is connected to the ground line GL, and the control terminal is the gate electrode G. When the discharge signal 7D becomes high level, the switching element 70 becomes conductive, and the WW output 7A (potential of the capacitor 69A) generated at the output terminals 61c, 62c drops rapidly to the reference potential. In the following, making the switching element 70 conductive and setting the WW output 7A to the reference potential in this manner is also referred to as discharging the electric 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 a 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 section 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 (potential of the power supply line PL) at a predetermined voltage when an enable signal 7B (voltage) equal to or higher than a threshold value is supplied from the buffer circuit 74 to the control terminal 63a. The output voltage of the regulator 63 (the above-mentioned predetermined voltage) is, for example, 3V when the counter 67 is composed of a CMOS or the like. The operating voltage of the non-volatile 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 insulating 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, 31B) as a control signal. For example, the switch 64 includes a switching element such as a MOS, a TFT, or a FET, the first terminal 64a and the second terminal 64b are a source electrode and a drain electrode, 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, 31B, and when the potential of the gate electrode becomes equal to or higher than a threshold value, the switch 64 is in a state (on state) in which the source electrode and the drain electrode can be conductive. The switch 64 may be provided outside the regulator 63, and may be an external device such as a relay.

[0044] The AND circuit 72 outputs a signal 7E (second signal) that becomes H level when the enable signal 7B is H level and the output signal of the regulator 63 is equal to or higher than a predetermined threshold (H level) to the delay circuit 73. The delay circuit 73 supplies a reset signal 7R generated using the signal 7E to the counter 67 and the nonvolatile memory 68. The reset signal 7R becomes H level after a predetermined delay time has elapsed since the input signal 7E becomes H level, and becomes L level when the signal 7E becomes L level after that. The reset signal 7R can also be regarded as a second signal equivalent to the signal 7E. The counter 67 and the nonvolatile memory 68 stop counting operation during the period when the reset signal 7R is L level. Hereinafter, the counter 67 and the nonvolatile memory 68 stop counting operation, which is also referred to as initializing or resetting the counter 67 and the nonvolatile memory 68. The buffer circuit 74, the AND circuit 72, and the delay circuit 73 constitute a signal relay circuit 75.

[0045] The multiple rotation information detection unit 3 includes magnetic sensors 51, 52 and analog comparators 65, 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 terminal 51p of the magnetic sensor 51 is connected to the power 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 terminal 65p of the analog comparator 65 is connected to the power 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 the first input terminal 67a of the counter 67. The analog comparator 65 outputs a signal from the output terminal 65b that is at H level when the output voltage of the magnetic sensor 51 is equal to or higher than a threshold value and is at L level when the output voltage is less than the threshold value. In addition, the analog comparator 65 may be configured to have two input terminals, to which the output terminals 51a and 51b of the magnetic sensor 51 in FIG. 2(C) are connected, and the analog comparator 65 may compare the voltages of 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, which is at H level when the output voltage of the magnetic sensor 52 is equal to or higher than a threshold value, and is at L level when the output voltage is lower than the threshold value.

[0047] The counter 67 counts the multiple rotation information of the rotating shaft SF using the power supplied from the battery 32. The counter 67 includes, for example, a CMOS logic circuit. The counter 67 operates using the 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 processing using the voltage supplied via the first input terminal 67a and the voltage supplied via the second input terminal 67b as detection signals. Furthermore, after the counting processing and the writing processing to the non-volatile memory 68 are completed, the counter 67 sets the discharge signal 7D to H level to make the switching element 70 conductive, and discharges the charge accumulated in the capacitor 69A to discharge the electric signal generating units 31A, 31B (lowers the level of the WW output 7A). As a result, the enable signal 7B becomes L level, and the regulator 63 is turned off. In the following, discharging the electric signal generating units 31A, 31B is also referred to as resetting the WW output 7A.

[0048] The nonvolatile memory 68 stores (performs a write operation) at least a part of the rotational position information (e.g., multiple rotation information) detected by the detection unit 13 using power supplied from the battery 32. The nonvolatile memory 68 stores the result of counting by the counter 67 (multiple rotation information) 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 stop counting operations and writing operations to the storage unit while the reset signal 7R output from the delay circuit 73 is at L level. Furthermore, the counter 67 and the nonvolatile memory 68 perform counting operations and writing to the storage unit or reading 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 H level. The delay time of the reset signal 7R (the time from when the output signal 7E of the AND circuit 72 rises to when the reset signal 7R rises) is set to a time that slightly exceeds the time until the voltage of the power line PL reaches or exceeds a predetermined threshold value and the magnetic detection unit 12 and the counter 67 operate correctly. The storage unit 14 in Fig. 1 includes a non-volatile memory 68, and is capable of retaining information written thereto 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, and 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 for stabilizing the operation of the regulator 63 (improving load response, improving pulsation (ripple), preventing oscillation, etc.). The constants of the capacitors 69B and 69C may be set 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 to when the magnetic detection unit 12 writes the rotational position information to the nonvolatile memory 68. The input capacitor 69B can be omitted. The charge of the output capacitor 69C is gradually discharged by a minute leak current.

[0050] When the output capacitor 69C is empty, the output capacitor 69C needs to be charged when the regulator 63 is turned on during the intermittent operation by the electric signal generating units 31A and 31B, and the voltage of the battery 32 drops instantaneously. After the output capacitor 69C is charged, the voltage of the battery 32 returns to normal and the regulator 63 operates stably. In this regard, it is also possible to adopt a configuration in which, for example, after the counting operation of the counter 67 is completed, the output of the output capacitor 69C is discharged and the reset signal 7R is set to a low level. However, in this configuration, when the rotating shaft SF rotates at high speed and the interval at which the regulator 63 is turned on becomes short, the next WW output 7A rises and the regulator 63 turns on before the voltage of the battery 32 is sufficiently restored, so that the voltage of the battery 32 gradually drops, and the voltage of the power supply line PL becomes constantly lower than the threshold value, which may cause the magnetic detection unit 12 and the like to be unable to operate accurately. In addition, the time it takes for the voltage of the battery 32 to return to normal becomes even more noticeable when the internal resistance of the battery 32 becomes large. In contrast, 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 in FIG. 1 with power obtained from, for example, an AC power supply (not shown), and can supply a DC voltage obtained from the power to the secondary battery 37 of the battery 32. During at least a portion of a period during which the power supply unit MCE of the motor control unit MC can supply power (for example, a period during which 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 by this power. During a period during which the power supply unit MCE of the motor control unit MC cannot supply power (for example, a period during which 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 an electric signal 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 signal 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 signal generated in the electric signal generating units 31A and 31B by the rotation of the rotating shaft SF. The secondary battery 37 may also be charged by the power generated by a generator (not shown) by the rotation of the rotating shaft SF driven by the motor M.

[0053] The encoder device EC according to this embodiment selects whether power is to be supplied to the position detection system 1 from the primary battery 36 or the secondary battery 37 when the supply of power from the outside is cut off. The power supply system 2 includes a power supply switch (power supply selection section, selection section) 38, which switches (selects) whether power is to be supplied 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 the secondary battery 37 to supply power, and does not cause the primary battery 36 to supply power. This threshold is set based on the power consumed by the position detection system 1, and is set to, for example, equal to or greater than the power to 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 the secondary battery 37 to supply power, and does not cause the primary battery 36 to supply power. Also, when the remaining charge of the secondary battery 37 is less than the threshold, the power supply switch 38 causes the primary battery 36 to supply power, and does not cause the secondary battery 37 to supply power. The power supply switch 38 may, for example, also function as a charger that controls the charging of the secondary battery 37, and may determine whether the remaining charge of the secondary battery 37 is equal to or greater than a threshold value using information on the remaining charge of the secondary battery 37 used to control the charging.

[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 (eg, replacement) of the battery 32, or the maintenance is performed only infrequently. The battery 32 may include at least one of the primary battery 36 and the secondary battery 37. In the above embodiment, power is alternatively supplied from the primary battery 36 or the secondary battery 37, but power may be supplied from the primary battery 36 and the secondary battery 37 in parallel. For example, 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 according to 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. 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. Fig. 5 is a timing chart showing the operation of the multiple rotation information detection unit 3 when the rotating shaft SF rotates counterclockwise (forward rotation). The timing chart showing the operation of the multiple rotation information detection unit 3 when the rotating shaft SF rotates counterclockwise (reverse rotation) is the time inverted version of the chart in Fig. 4, so its explanation will be omitted.

[0057] In the "magnetic field" of Fig. 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, where the output of the current flowing in one direction is positive (+) and the output of the current flowing in the opposite direction is negative (-). The "enable signal" indicates the enable signal 7B (electric 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" indicates the output of the regulator 63 (electric 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 FIG. 5 are magnetic fields formed on the magnetic sensors 51 and 52. The magnetic field formed by the magnet 11 is indicated by a long dashed line, the magnetic field formed by the bias magnet is indicated by a short dashed line, and the composite magnetic field is indicated 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, the output from the first output terminal is indicated by a dashed line, and the output from the second output terminal is indicated 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 the analog comparator are constantly driven is indicated in "constant drive", and the output when the magnetic sensor and the analog comparator are intermittently driven is indicated in "intermittent drive".

[0059] When the rotation shaft 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 the angular positions of 45° and 225°. The first electric signal generating unit 31A also outputs a current pulse flowing in the reverse direction (- of the "first electric signal generating unit") at the angular positions of 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 the angular positions of 90° and 270°. The second electric signal generating unit 31B also outputs a current pulse flowing in the forward direction (- of the "second electric signal generating unit") at the angular positions of 180° and 0° (360°). Therefore, the enable signal switches to the H level at each of the angular positions of 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 the H level.

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

[0061] Moreover, the output of the magnetic sensor 52 has a positive sine wave shape 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 the L level when no power is being supplied, and becomes the 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 pair of these signal levels is represented as (H, L). In Fig. 5, the pair of signal levels at an angular position of 180° is (L, H), the pair of signal levels at an angular position of 225° is (H, H), and the pair of signal levels at an angular position of 270° is (H, L).

[0063] When one or both of the detected A-phase and B-phase signals 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 and B-phase signals 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 set is (H, H) and the current signal level is (H, L), the previous detection had an angular position of 225° and the current detection has an angular position of 270°, so it is known that the rotation is counterclockwise (forward rotation). If the current level set is (H, L) and the previous level set is (H, H), the counter 67 supplies an up signal indicating that the counter is to be incremented to the non-volatile memory 68. When the up signal from the counter 67 is detected, the non-volatile memory 68 updates the stored multi-rotation information to a value incremented by 1. In addition, in the case of reverse rotation, the counter 67 supplies a down signal indicating that the counter is to be decremented to the non-volatile memory 68. At this time, the non-volatile memory 68 updates the stored multi-rotation information to a value decremented by 1. 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 flow chart of Fig. 6 and the waveform diagram of 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 in FIG. 6, the WW output 7A of the electric signal generating unit 31A or 31B in FIG. 4 is generated, and the enable signal 7B (see FIG. 7(C)) of the buffer circuit 74 becomes H level. The WW output 7A is generated intermittently in a short cycle as shown in FIG. 7(A), but the operation of the WW output 7A within one cycle will be described below as shown in FIG. 7(B) to (E). The signal generated by the electric signal generating unit 31A, 31B is a pulse as shown in FIG. 5, but since the capacitor 69A is provided between the output terminals 61c, 62c and the ground line GL, the WW output 7A drops to the reference potential relatively slowly. Then, in step 104, the regulator 63 turns on (operates) in response to the enable signal 7B, and the potential of the power supply line PL connected to the output terminal 63c of the regulator 63 rises as shown by the dotted waveform (see FIG. 7(B)). At this time, the signal 7E of the AND circuit 72 becomes H level.

[0066] Furthermore, in step 106, after a predetermined time Δt has elapsed, the reset signal 7R of the delay circuit 73 becomes H level (see FIG. 7(B)), the counter 67 and the nonvolatile memory 68 start operating in step 108, and in step 110, the counter 67 writes the rotation information (the above-mentioned up signal or down signal) to the nonvolatile memory 68. Data 7RD in FIG. 7(B) shows an example of a signal exchanged between the counter 67 and the nonvolatile memory 68. Then, in step 112, the counter 67 sets the discharge signal 7D to H level (see FIG. 7(E)), and in response, the switching element 70 becomes conductive and the WW output 7A decreases (is discharged), in step 114, the enable signal 7B of the buffer circuit 74 becomes L level, and in step 116, the output 7E of the AND circuit 72 becomes L level (see FIG. 7(D)), the regulator 63 turns off (stops operating), and the potential of the power line PL decreases. Then, in step 118, the reset signal 7R goes to L level (see FIG. 7B), and the counter 67 and non-volatile 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 each pulse signal of the WW output 7A is generated intermittently at a short period, as shown in FIG. 7(A), the WW output 7A is reset and the regulator 63 is turned off every time the processing of the counter 67 is completed, so that the potential (dotted curve) of the power line PL connected to the output terminal of the regulator 63 hardly drops. Therefore, it is possible to suppress the voltage drop of the battery 32 when the pulse signal of the WW output 7A is generated and the regulator 63 is turned on, and the voltage of the battery 32 can be reliably restored to its original voltage. Therefore, even if the rotating shaft SF rotates at high speed, it is possible to accurately supply and cut off the power from the battery 32 to the position detection system 1 (multi-rotation information detection unit 3), and it is possible to reduce the power consumption of the battery 32 and obtain the rotation information of the rotating shaft SF with high accuracy. This makes it possible to eliminate the maintenance (e.g., replacement) of the battery 32 or to reduce the frequency of the 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 electric signal generating unit 31A (electrical signal generating section) that generates a WW output 7A (electrical signal) due to a change in the magnetic field due to the rotation of the magnet 11, and a signal relay circuit 5 (circuit section) that outputs the WW output 7A or an enable signal 7B (first signal) output from the electric 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 electric signal generating unit 31A is discharged by the discharge signal 7D (the WW output 7A is reduced) and the regulator 63 is turned off, thereby preventing the subsequent power consumption of the battery 32. In addition, since the output of the electric signal generating unit 31A is discharged instead of the output of the regulator 63, the reduction in the output of the regulator 63 (the potential of the power supply of 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 every time each WW output 7A (pulse signal) is generated can be reduced, and the voltage drop of the battery 32 can be reduced, thereby shortening the recovery time of the voltage of the battery 32. Therefore, even when the rotating shaft SF rotates at high speed, the power consumption of the battery 32 can be reduced and power can be supplied to the position detection system 1, and the rotation information of the rotating shaft SF can be obtained with high accuracy.

[0070] In this embodiment, an output capacitor 69C is provided. This capacitor 69C stabilizes the operation of the regulator 63 (improving load response, etc.). Furthermore, since 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 each WW output 7A is generated can be reduced, thereby reducing the amount of voltage drop of the battery 32 and shortening the time it takes for the voltage of the battery 32 to return.

[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 non-volatile memory 68 of the position detection system 1, and the counter 67 and non-volatile memory 68 are initialized by the reset signal 7R (stopping the counting operation). This prevents malfunction due to an unstable signal caused by a 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 surface of the magnet 11, are perpendicular to the longitudinal direction of the magnetically sensitive member 47, and the unnecessary magnetic field components do not adversely affect the generation of a magnetic domain wall from one end to the other end in the longitudinal direction of the magnetically sensitive member 47 due to the reversal of the AC magnetic field caused by the rotation of the magnet 11. Therefore, even if the magnetically 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-output 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 detection unit 3 within a short time after the electric signal is generated in the electric signal generating unit 31A, and the multi-rotation information detection unit 3 is dynamically driven (intermittently driven). After the detection and writing of the multi-rotation information is completed, the power supply to the multi-rotation information detection unit 3 is cut off, but the count value is stored in the memory unit 14 and is therefore retained. This sequence is repeated every time a predetermined position on the magnet 11 passes near the electric signal generating unit 31A, even in a state where the power supply from the outside is cut off. In addition, the multi-rotation information stored in the memory unit 14 is read out to the motor control unit MC or the like when the motor M is next started, and is used to calculate the initial position of the rotation axis SF, etc. In such an encoder device EC, the battery 32 supplies at least a part of the power consumed by the position detection system 1 in response to the electric signal generated by the electric signal generating unit 31A, so that the battery 32 can have a long life. This makes it possible to eliminate maintenance (e.g., replacement) of the battery 32 or reduce the frequency of 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 the way, when a magnetosensitive wire such as a Wiegand wire is used, even if the rotation speed of the magnet 11 is extremely low, a pulse current (electrical signal) can be output from the electric signal generating unit 31A. Therefore, even if the rotation speed of the rotating shaft SF (magnet 11) is extremely low, for example, in a state where power is not supplied to the motor M, the output of the electric signal generating unit 31A can be used as an electric signal. Note that an amorphous magnetostrictive wire can also be used as the magnetosensitive wire (first magnetosensitive part 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] The second embodiment will be described with reference to Figs. 8 to 10. In Figs. 8, 9, and 10, the parts corresponding to Figs. 4, 6, and 7 are denoted by the same reference numerals, and detailed description 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 the output terminals 61c, 62c of the rectifier stacks 61, 62 connected to the electric signal generating units 31A, 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 that the counting operation has ended 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 becomes H level (high level), the output of the OR circuit 71 becomes H level, and when all of the WW output 7A, the switching signal 7ND, and the processing completion signal 7TC become L level (low level), the output of the OR circuit 71 becomes L level. The output of the OR circuit 71 is supplied as an enable signal 7B to a first input part of the AND circuit 72 and 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 the non-volatile memory 68 via the delay circuit 73. The OR circuit 71, the AND circuit 72, and the delay circuit 73 constitute a signal relay circuit 75A.

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

[0076] In the backup operation, as an example, the power supply unit MCE (main power supply) is turned off, the 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 the L level. This allows the counter 67 to recognize that the operation has been switched from normal operation to backup operation. In the backup operation, in order to suppress the consumption of power from the battery 32, the regulator 63 is turned on during a period in which the WW output 7A of the electric signal generating units 31A, 31B is equal to or higher than a predetermined threshold, and power is supplied to the magnetic detection unit 12, the counter 67, and the non-volatile memory 68 during that period to obtain rotation information of the rotating shaft SF.

[0077] However, when shifting from normal operation to backup operation, there is a risk that power cannot be supplied to the magnetic detection unit 12 and the like 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, turns on the regulator 63, and supplies power to the magnetic detection unit 12 and the like. Note that, during normal operation, as an example, the processing completion signal 7TC may always be at H level. After that, after the rotation information is obtained, the counter 67 sets the switching signal 7ND to L level. After this, a smooth shift to the above-mentioned backup operation can be made. Since the configuration of this embodiment other than this is the same as that of the first embodiment, 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 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 becomes L level (see FIG. 10(A)). In response to this, in step 122, the counter 67 sets the processing completion signal 7TC to H level (see FIG. 10(B)). After this, in step 104, the enable signal 7B of the OR circuit 71 becomes H level, the regulator 63 operates, the potential of the power supply line PL becomes H level, and the signal 7E of the AND circuit 72 becomes H level. Then, in step 106, after a predetermined time has elapsed, the reset signal 7R becomes H level (see FIG. 10(C)), and in step 108, the counter 67 and the 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 off.

[0080] Then, in step 124, the counter 67 sets the process 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)), and in response to this, the switching element 70 is turned on and the WW output 7A drops (the electric signal generating units 31A and 31B are discharged). Then, the enable signal 7B of the OR circuit 71 goes to L level, and 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 in FIG. 6. Then, when the WW output 7A rises, the operations of steps 104 to 118 in 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 to H level 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., and 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 by efficiently using the power of the battery 32, 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 generating unit 31A (electric signal generating section) that generates a WW output 7A (electrical signal) by 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) to the position detection system 1 via the WW output 7A. 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 detects 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, a 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 obtained 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 is accurately obtained and stored, a smooth transition to an 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 can be made. The electric signal generating unit 31A has a magnetism-sensitive part 41A whose magnetic properties change with the change 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 includes 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 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, since the counter 67 outputs the process completion signal 7TC for operating the regulator 63, the outputs of the electric signal generating units 31A and 31B can be used smoothly. The element that outputs the process completion signal 7TC does not necessarily have to be the counter 67. In each of the above-mentioned embodiments, as shown in Fig. 3(A), the tip portions of the first and second magnetic bodies 45A, 46A of the electric signal generating unit 31A are arranged near the portions of the surface (N pole 16A to S pole 16D) and the back surface (S pole 17A to N pole 17D) of the magnet 11 that have different polarities at the same angular positions, so that the electric signal generating unit 31A can be further miniaturized. Note that, as in the electric signal generating unit 31C of the modified example shown in Figs. 3(D) and (E), the tip portion of the first magnetic body 45C on one end side of the magnetically sensitive member 47 may be arranged near the portion of the surface of the magnet 11 that has a certain polarity (e.g., N pole 16A or S pole 16B, etc.), and the tip portion of the second magnetic body 46C on the other end side of the magnetically sensitive member 47 may be arranged near the portion of the surface of the magnet 11 that has a different polarity (e.g., S pole 16D or N pole 16A, etc.). In this case, the first and second magnetic bodies 45C, 46C guide magnetic field lines from two parts of the magnet 11 with different polarities (e.g., the north pole 16A and the south pole 16D) at different positions in the rotation direction in the length direction of the magnetically sensitive member 47. In the electric signal generating unit 31C as well, a magnetic circuit MC2 is formed so as to pass from the magnet 11 through the first magnetic body 45C, the magnetically sensitive member 47, and the second magnetic body 46C, so that the magnetically sensitive member 47 can efficiently output a stable pulse due to the reversal of the AC magnetic field caused by the rotation of the magnet 11 without being influenced by unnecessary magnetic fields on the side surfaces of the magnet 11. The magnet 11 may have any configuration, and the electric signal generating units 31A, 31B may also have any configuration.

[0085] In addition, in the above embodiment, two electric signal generating units 31A, 31B are provided, but the encoder devices EC, ECA may include only one electric signal generating unit 31A. Furthermore, the encoder devices EC, ECA may include 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, the magnet 11 is an eight-pole magnet having four poles in the circumferential direction and two poles in the thickness direction, but this is not limited to the configuration and can be modified as appropriate. For example, the magnet 11 may have two poles or four or more poles in the circumferential direction. In the above embodiment, the position detection system 1 detects the rotational position information of the rotating axis SF (moving part) as the position information, but at least one of the position, speed, and acceleration in a predetermined direction may be detected as the position information. The encoder devices EC and ECA may include a rotary encoder or a linear encoder. The encoder devices EC and ECA may be such that the power generation unit and the detection unit are provided on the rotating axis SF and the magnet 11 is provided outside the moving body (for example, the rotating axis SF) so that the relative position between the magnet and the detection unit changes with the movement of the moving part. The position detection system 1 does not need to detect the multiple rotation information of the rotating axis SF, and the multiple rotation information may be detected by a processing unit outside the position detection system 1.

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

[0088] The electric signal generating units 31A and 31B may also supply at least a part of the power consumed by the position detection system 1. For example, the electric signal generating units 31A and 31B may supply power to a processing unit in the position detection system 1 that consumes relatively less power. The electric supply system 2 may not supply power to a part of the position detection system 1. For example, the electric power 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 outside the power 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 part of the position detection system 1. For example, the electric power 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 accompanying a change in a magnetic field accompanying 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, ECA.

[0089] [Drive system] An example of a drive device will be described. FIG. 11 is a diagram showing an example of a drive device MTR. In the following description, components that are the same as or equivalent to those in the above-mentioned embodiment are 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 part (drive part) 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 part. In addition to fixing the scale S, an encoder device EC is attached. The encoder device EC is an encoder device according to the above-mentioned embodiment, modified example, or combination thereof.

[0091] In this driving device MTR, the motor control unit MC shown in Fig. 1 controls the main body unit BD using the detection result of the encoder device EC. Since the driving device MTR does not require or only requires a low frequency of battery replacement for the encoder device EC, it is possible to reduce maintenance costs. Note that the driving device MTR is not limited to a motor device, and may be another driving 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 the 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 rotary shaft SF of the 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 are 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, etc. Therefore, by using the output from the encoder device EC, the angular position of the turntable TB can be detected. 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 shows a schematic view of a part (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 are 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 bearings 101a and 101b at the joint portion JT. The connecting portion 102a is provided integrally with the rotating shaft SF2. The rotating shaft SF2 is inserted into both the bearings 101a and 101b at the joint portion 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, and transmits 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. In addition, the scale S of the encoder device 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 driving device MTR to rotate the rotating shaft SF, this rotation is transmitted to the rotating shaft SF2 via the reduction gear RG. The rotation of the rotating shaft SF2 rotates the connecting part 102a integrally, and as a result, the second arm AR2 rotates relative to the first arm AR1. At that time, the encoder device EC detects the angular position of the rotating shaft SF, etc. Therefore, the angular position of the second arm AR2 can be detected by 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 device 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 part; a magnet that moves due to the movement of the moving part; an electric signal generation unit that generates an electric signal due to a change in the magnetic field due to the movement of the magnet; and a circuit unit that outputs the output of the electric signal generation unit, which changes due to a control signal from the position detection unit, to the position detection unit. 2) An encoder device as described in 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 by 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 to the position detection unit the electrical signal 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 part; a magnet that moves with the movement of the moving part; an electric signal generating 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 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 until power is supplied from the power supply unit using the electric signal. 9) An encoder device as described in 8) further comprising a circuit section that outputs, when the position information is detected by the position detection section, an output from the electrical signal generating section that changes in response to a control signal from the position detection section to 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 decreased 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 decreased. 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 claims 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 due to 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 sector-shaped portion, 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 described in 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 for moving 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 part, a magnet that moves with the movement of the moving part, an electric signal generating unit that generates an electric signal with a change in 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. 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...magnetic sensing 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 shaft, 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 a magnetic field caused by the movement of the magnet; a circuit section that changes the electrical signal according to a control signal received from the position detection section and outputs an electrical signal based on the control signal to the position detection section; Equipped with The position detection unit a first input for receiving the electrical signal; a second input provided with a different power than the electrical signal; Equipped Encoder device.

2. a storage unit that stores the charge of the electrical signal; The encoder device according to claim 1 , wherein the electrical signal changes when the charge in the storage unit is discharged in response to 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 has decreased.

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

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

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

7. The encoder device according to claim 1 , wherein the electrical signal is outputted repeatedly and intermittently in accordance with the movement of the moving part.

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 includes an angle detection unit that detects angular position information within one rotation of the rotation shaft; a multiple rotation information detection unit that detects multiple rotation information of the rotation shaft as the position information; The encoder device according to claim 8.

10. 2. The encoder apparatus of claim 1, wherein the power supplied to the second input is independent of the control signal.

11. 5. The encoder apparatus of claim 4, wherein the second input is powered by the power supply 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 drive device comprising: a power supply unit that supplies power to the moving unit.

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

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

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