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

Abstract

Even when the object being tested is rotating at a high speed, power consumption is suppressed, improving the reliability of the detection results. [Solution] An encoder device is provided comprising: a position detection unit that detects the position information of a moving part when power is supplied from a power source; a magnet that moves as a result of the movement of the moving part; an electrical signal generating unit that generates an electrical signal as a result of the 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 electrical signal. The encoder device is configured such that when the power supply from the power source is interrupted, the position detection unit is supplied with power from the power supply unit regardless of the state of the electrical signal, and performs the detection of the position information.

Description

Technical Field

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

Background Art

[0002] As a conventional encoder device, there is known one that drives a non-powered multi-rotation detection circuit by self-power generation means using a Weigant wire or other magnetic power generation elements to detect multi-rotations even without power supply (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] According to an aspect of the present invention, there is provided an encoder device including a position detection unit that detects position information of a moving part, a magnet that moves by the movement of the moving part, 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 circuit unit that changes the electric signal by a control signal received from the position detection unit and outputs the electric signal based on the control signal to the position detection unit, wherein the position detection unit includes a first input that receives the electric signal and a second input to which power different from the electric signal is supplied. Also, the following aspects of the invention are described in this specification. According to a first aspect, there is provided an encoder device including a position detection unit that detects position information of a moving part, a magnet that moves by the movement of the moving part, 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 circuit unit that outputs an output of the electric signal generation unit that changes by a control signal from the position detection unit to the position detection unit.

[0005] According to a second embodiment, an encoder device is provided comprising: a position detection unit that detects the position information of a moving part when power is supplied from a power source; a magnet that moves with the movement of the moving part; an electrical signal generating unit that generates an electrical signal due to the change in the magnetic field caused by the movement of the magnet; and a power supply unit that supplies power to the position detection unit with the electrical signal, wherein if the power supply from the power source is interrupted, power is supplied from the power supply unit regardless of the state of the electrical signal, and the encoder device is provided that detects the position information.

[0006] According to a third aspect, a drive device is provided comprising an encoder device as described above and a power supply unit that supplies power to its moving part. According to a fourth aspect, a stage apparatus is provided comprising a moving object and a drive device of a third aspect for moving the moving object. According to a fifth aspect, a robotic device is provided comprising a drive device according to a third aspect and an arm that moves relative to the drive device.

[0007] According to the sixth aspect, a method for using an encoder device is provided, comprising: a position detection unit that detects the position information of a moving part when power is supplied from a power source; a magnet that moves due to the movement of the moving part; an electrical signal generating unit that generates an electrical 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 electrical signal, wherein if the power supply to the position detection unit is interrupted, power is supplied from the power supply unit regardless of the state of the electrical signal, and the device is used to detect the position information. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing an encoder device according to the first embodiment. [Figure 2] (A) is a perspective view showing the magnet, electrical signal generation unit, and magnetic sensor in Figure 1, (B) is a plan view showing the magnet, etc. in Figure 2(A), and (C) is a circuit diagram showing the magnetic sensor in Figure 2(A). [Figure 3](A) is a plan view showing the magnet and electrical signal generating unit of Figure 2(A), (B) and (C) are cross-sectional views of Figure 3(A), respectively, (D) is a plan view showing a modified example, and (E) is a side view of Figure 3(D). [Figure 4] This figure shows the configuration of the power supply system and the multi-turn information detection unit of the encoder device shown in Figure 1. [Figure 5] This figure shows the operation of the encoder device in forward rotation. [Figure 6] This flowchart shows an example of operation during high-speed rotation. [Figure 7] Figures (A), (B), (C), (D), and (E) are diagrams showing predetermined signals corresponding to the operation in Figure 6. [Figure 8] This figure shows the configuration of the power supply system and the multi-turn information detection unit of the encoder device according to the second embodiment. [Figure 9] This flowchart shows an example of the operation when the power is turned off according to the second embodiment. [Figure 10] Figures (A), (B), (C), (D), and (E) are diagrams showing predetermined signals corresponding to the operation in Figure 9. [Figure 11] This figure shows an example of a drive mechanism. [Figure 12] This is a diagram showing an example of a stage setup. [Figure 13] This figure shows an example of a robotic device. [Modes for carrying out the invention]

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

[0010] The encoder device EC comprises a position detection system (position detection unit) 1 and a power supply system (power supply unit) 2. The position detection system 1 detects the rotational position information of the rotating shaft SF. The encoder device EC is a so-called multi-turn absolute encoder and detects rotational position information including multi-turn information indicating the number of rotations of the rotating shaft SF, and angular position information indicating an angular position (rotation angle) of less than one rotation. The encoder device EC comprises a multi-turn information detection unit 3 that detects the multi-turn 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 (for example, the angle detection unit 4) operates by receiving power from a device (for example, a drive unit, a stage unit, or a robot unit) on which the encoder device EC is mounted (for example, a drive unit, a stage unit, or a robot unit) when the power supply (for example, the main power supply) of the device is turned on (normal state). Also, at least a part of the position detection system 1 (for example, the multi-turn information detection unit 3) operates by receiving power from the power supply system 2 when the power supply (for example, the main power supply) of the device on which the encoder device EC is mounted is turned off (emergency state, backup state, etc.). For example, when the power supply from the device on which the encoder device EC is mounted is cut off, the power supply system 2 intermittently supplies power to at least a part of the position detection system 1 (for example, the multi-turn 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 (for example, multi-turn information) when power is supplied from the power supply system 2.

[0012] The multi-rotation information detection unit 3 detects multi-rotation information, for example, by magnetism. The multi-rotation information detection unit 3 includes, for example, a magnet 11, a magnetic detection unit 12, a detection unit 13, and a storage unit 14. The magnet 11 is mounted on a disk 15 fixed to the rotation axis SF. 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 as the rotation axis SF rotates. The strength and direction of the magnetic field on the magnetic detection unit 12 formed by the magnet 11 change as the rotation axis SF rotates. The magnetic detection unit 12 detects the magnetic field formed by the magnet 11, and the detection unit 13 detects the 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 (angle position information) within one rotation of the scale. For example, when it is an optical encoder, for example, by reading the pattern information of the scale with a light receiving element, the angle position within one rotation of the rotation axis SF is detected. The pattern information of the scale is, for example, light and dark slits on the scale. The angle detection unit 4 detects the angle position information of the same rotation axis SF 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 axis 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 to 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 (irradiation unit, light emitting unit) irradiates the scale S with light. The light receiving sensor 22 (light detection unit) detects the light irradiated from the light emitting element 21 and passing 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. Note that the angle detection unit 4 may be a reflection type. Then, the light receiving sensor 22 supplies a signal indicating the detection result to the detection unit 23. The detection unit 23 detects the angle position of the rotation axis SF using the detection result of the light receiving sensor 22. For example, the detection unit 23 detects the angle position of the first resolution using the result of detecting the light from the absolute scale. Further, the detection unit 23 performs interpolation calculation on the angle position of the first resolution using the result of detecting the light from the incremental scale, thereby detecting the angle position of the second resolution higher than the first resolution.

[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 synthesizing unit 26 and an external communication unit 27. The synthesizing unit 26 acquires the angular position information of the second resolution detected by the detection unit 23. Also, the synthesizing unit 26 acquires the multi-rotation information of the rotation shaft SF from the storage unit 14 of the multi-rotation information detection unit 3. The synthesizing 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, and calculates 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 synthesizing 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 less than one rotation.

[0017] The synthesizing 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 by wire or wirelessly. The external communication unit 27 supplies the rotational position information in digital format to the communication unit MCC of the motor control unit MC. The motor control unit MC appropriately decodes the rotational position information from the external communication unit 27 of the angle detection unit 4. The motor control unit MC controls the rotation of the motor M by controlling the power (drive power) supplied to the motor M using the rotational position information.

[0018] The power supply system 2 comprises first and second electrical signal generating units 31A and 31B, a battery 32, and a switching unit 33. The electrical signal generating units 31A and 31B each generate an electrical signal by the rotation of the rotating shaft SF. This electrical signal includes, for example, a waveform in which power (current, voltage) changes over time. The electrical signal generating units 31A and 31B each generate power as an electrical signal by a magnetic field that changes based on the rotation of the rotating shaft SF. For example, the electrical signal generating units 31A and 31B generate power by a change in the magnetic field formed by a magnet 11 used by the multi-rotation information detection unit 3 to detect the multi-rotation position of the rotating shaft SF. The electrical signal generating units 31A and 31B are arranged so that their relative angular position with respect to the magnet 11 changes with the rotation of the rotating shaft SF. The electrical signal generating units 31A and 31B each generate a pulse-like electrical signal when the relative position between the electrical signal generating units 31A and 31B and the magnet 11 reaches a predetermined position.

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

[0020] The switching unit 33 switches the supply of power from the battery 32 to the position detection system 1 based on the electrical signals generated by the electrical signal generation units 31A and 31B. For example, the switching unit 33 starts supplying power from the battery 32 to the position detection system 1 when the level of the electrical signals generated by the electrical signal generation units 31A and 31B exceeds a threshold. For example, the switching unit 33 starts supplying power from the battery 32 to the position detection system 1 when the electrical signal generation units 31A and 31B generate power above a certain level. Also, the switching unit 33 stops supplying power from the battery 32 to the position detection system 1 when the level of the electrical signals generated by the electrical signal generation units 31A and 31B falls below a threshold. For example, the switching unit 33 stops supplying power from the battery 32 to the position detection system 1 when the power generated by the electrical signal generation units 31A and 31B falls below a certain threshold. For example, when pulsed electrical signals are generated by the electrical signal generation units 31A and 31B, the switching unit 33 starts supplying power from the battery 32 to the position detection system 1 when the level (power) of this electrical 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 power from the battery 32 to the position detection system 1 after a predetermined time has elapsed since the level (power) of this electrical signal changed to the L level. Furthermore, the encoder device EC is configured to use the electrical signals (pulse signals) generated by the electrical signal generation units 31A and 31B as switching signals (trigger signals) for supplying power from the battery 32 to the position detection system 1.

[0021] Figure 2(A) is a perspective view showing the magnet 11, electrical signal generation units 31A and 31B, and two magnetic sensors 51 and 52, which constitute the magnetic detection unit 12, in Figure 1. Figure 2(B) is a plan view of the magnet 11, etc., in Figure 2(A) as seen from a direction parallel to the rotation axis SF. Figure 2(C) is a circuit diagram of the magnetic sensor 51. Note that in Figures 2(A), etc., the rotation axis SF in Figure 1 is represented by a straight line. In Figures 2(A) and (B), the magnet 11 is configured such that, upon rotation, the direction and strength of the magnetic field in the axial direction (also called the axial direction), which is parallel to the straight line (axis of symmetry) passing through the center of the rotation axis SF, changes. The magnet 11 is, for example, an annular member coaxial with the rotation axis SF. As an example, the magnet 11 consists of a first annular magnet consisting of fan-shaped N poles 16A, S poles 16B, N poles 16C, and S poles 16D, each with an opening angle of 90°, arranged in order to surround the rotation axis SF, and a second annular magnet consisting of S poles 17A, N poles 17B, S poles 17C, and N poles 17D, which have the same shape as N poles 16A to S poles 16D and are attached to one side of N poles 16A to S poles 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 called the circumferential direction or rotational direction) around the rotation axis SF. The main surfaces of magnet 11, the front surface (the surface opposite to the motor M in Figure 1) and the back surface (the surface on the same side as the motor M), are both approximately perpendicular to the rotation axis SF. In other words, in magnet 11, the angle (e.g., the position of the N poles and S poles) between the N poles 16A to S poles 16D on the front surface and the S poles 17A to N poles 17D on the back surface is shifted by 90° (180° in phase), and the circumferential position (angular position) of the boundary between the N poles and S poles of N poles 16A to S poles 16D and the boundary between the S poles and N poles of S poles 17A to N poles 17D is approximately the same. The first and second annular magnets described above are a single magnet that is continuously integrated in the direction of movement (here, the circumferential direction, the rotational direction) or the axial direction and has multiple polarities, and may be hollow magnets with space inside them.

[0022] For the sake of explanation, when viewed from the front end of the rotating shaft SF (opposite the motor M in Figure 1), counterclockwise rotation will be referred to as forward rotation, and clockwise rotation as reverse rotation. Furthermore, the angle of forward rotation will be represented by a positive value, and the angle of reverse rotation will be represented by a negative value. Alternatively, when viewed from the rear end of the rotating shaft SF (the side of the motor M in Figure 1), counterclockwise rotation may 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 the south pole 16D and the north pole 16A in the circumferential direction is represented by position 11a, and the angular positions (boundaries between the north and south poles) obtained by sequentially rotating 90° from position 11a are represented by positions 11b, 11c, and 11d, respectively. In the first section, which is 90° counterclockwise from position 11a, the north pole is positioned on the front side of the magnet 11, and the south pole is positioned on the back side of the magnet 11. In this first section, the axial direction of the magnetic field of the magnet 11 is approximately parallel to the axial direction AD1 (see Figure 3(C)) that runs from the front side to the back side of the magnet 11. In this first section, the strength of the magnetic field is maximum midway between position 11a and position 11b, and minimum in the vicinity of positions 11a and 11b.

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

[0025] Thus, the axial direction of the magnetic field formed by the magnet 11 is sequentially reversed at positions 11a to 11d. The magnet 11 forms an alternating magnetic field with respect to a coordinate system fixed outside the magnet 11, in which the axial direction of the magnetic field is reversed as the magnet 11 rotates. The electrical signal generating units 31A and 31B are positioned on the outer surface of the magnet 11 in a direction intersecting the normal direction of the main surface of the magnet 11.

[0026] In this embodiment, the electrical signal generating units 31A and 31B are each provided separately from the magnet 11 in the radial direction (also referred to as the radial direction) or in a direction parallel to the radial direction, perpendicular to the rotation axis SF, and are not in contact with the magnet 11. The first electrical signal generating unit 31A includes a first magnetic sensing unit 41A, a first power generation unit 42A, a first set of first magnetic materials 45A, and a first set of second magnetic materials 46A. Note that one of the first magnetic material 45A and the second magnetic material 46A can be omitted. The first magnetic sensing unit 41A, the first power generation unit 42A, the first magnetic material 45A, and the second magnetic material 46A are fixed outside the magnet 11, and their relative positions with respect to each position on the magnet 11 change as the magnet 11 rotates. For example, in Figure 2(B), position 11b of the magnet 11 is positioned 45° counterclockwise from the first electrical signal generating unit 31A. When the magnet 11 rotates 1 full turn in the forward direction (counterclockwise) from this position, positions 11a, 11d, 11c, and 11b pass near the electrical signal generating unit 31A in that order.

[0027] The first magnetic-sensitive part 41A is a magnetic-sensitive wire such as a Wiegand wire. The first magnetic-sensitive part 41A experiences a large Barkhausen jump (Wiegand effect) due to the change in the magnetic field accompanying the rotation of the magnet 11. The first magnetic-sensitive part 41A is a cylindrical member with a rectangular projection image, and its axial direction is set in the circumferential direction of the magnet 11. Hereinafter, the axial direction of the first magnetic-sensitive part 41A, that is, the direction perpendicular to the circular (or polygonal, etc.) cross-section of the first magnetic-sensitive part 41A, will also be referred to as the longitudinal direction of the first magnetic-sensitive part 41A. For example, the length of the magnetic-sensitive part in the direction perpendicular to the cross-section of the magnetic-sensitive part (e.g., the first magnetic-sensitive part 41A) (axial direction, longitudinal direction, long side direction) is set to be longer than the length of the magnetic-sensitive part in the direction parallel to the cross-section of the magnetic-sensitive part (short side direction). When an alternating magnetic field is applied to the first magnetic-sensitive part 41A in its axial direction (long side direction), and the alternating magnetic field reverses, a magnetic domain wall is generated from one end to the other in the axial direction. Thus, the longitudinal direction (axial direction) of the magnetically sensitive part (for example, the first magnetically sensitive part 41A, etc.) in this embodiment is also called the easy magnetization direction, which is the direction in which magnetization is easily directed.

[0028] The first and second magnetic materials 45A and 46A are formed from ferromagnetic materials such as iron, cobalt, and nickel. The first and second magnetic materials 45A and 46A can also be called yokes. The first magnetic material 45A is provided between the surface of the magnet 11 and one end of the first magnetic-sensitive part 41A, and the second magnetic material 46A is provided between the back surface of the magnet 11 and the other end of the first magnetic-sensitive part 41A. The tips of the first and second magnetic materials 45A and 46A are positioned at the same angular position in the circumferential direction on the surface and back surface of the magnet 11. The polarities of the magnet 11 at the tips of the first and second magnetic materials 45A and 46A are always opposite to each other, and when the tip of the first magnetic material 45A is near the N pole 16A (or S pole 16B), the tip of the second magnetic material 46A is near the S pole 17A (or N pole 17B). Therefore, the first and second magnetic materials 45A and 46A guide magnetic field lines from two parts of the magnet 11 with different polarities (for example, the north pole 16A and the south pole 17A) that are located at the same position in the circumferential direction of the magnet 11, in the longitudinal direction of the first magnetic-sensitive part 41A. Then, the magnet 11, the first magnetic material 45A, the first magnetic-sensitive part 41A, and the second magnetic material 46A form a magnetic circuit MC1 (see Figure 3(A)) that includes magnetic field lines directed in the longitudinal direction of the first magnetic-sensitive part 41A. Note that a step (not shown) is provided at the periphery of the disk 15 in Figure 1, and a space is secured between the periphery of the disk 15 and the back surface of the magnet 11 in which the second magnetic material 46A can be inserted.

[0029] The first power generation unit 42A is a high-density coil wound around the first magnetic sensing unit 41A. Electromagnetic induction occurs in the first power generation unit 42A due to the generation of magnetic domain walls in the first magnetic sensing unit 41A, causing an induced current to flow. When the positions 11a to 11d of the magnet 11 shown in Figure 2(B) pass near the electrical signal generation unit 31A (the tips of the magnetic materials 45A and 46A), a pulsed current (electrical signal, power) is generated in the first power generation unit 42A.

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

[0031] As shown in Figure 2(A), the first magnetic sensing unit 41A, the first power generation unit 42A, and the portion of the first and second magnetic materials 45A and 46A on the side of the first magnetic sensing unit 41A are housed in a case 43A. Terminals 42Aa and 42Ab are provided on the case 43A. The high-density coil of the first power generation unit 42A has one end and the other end electrically connected to terminals 42Aa and 42Ab, respectively. The power generated by the first power generation unit 42A can be taken out to the outside of the first electrical signal generation unit 31A via terminals 42Aa and 42Ab.

[0032] The second electrical signal generating unit 31B is positioned at an angular position greater than 0° and less than 180° from the angular position where the first electrical signal generating unit 31A is positioned. The angle between the electrical signal generating units 31A and 31B is selected from a range of, for example, 22.5° to 67.5°, and is approximately 45° in Figure 2(B). The second electrical signal generating unit 31B has the same configuration as the first electrical signal generating unit 31A. The second electrical signal generating unit 31B comprises a second magnetic sensing unit 41B, a second power generation unit 42B, a second set of first magnetic materials 45B, and a second set of second magnetic materials 46B. The second magnetic sensing unit 41B, the second power generation unit 42B, and the second set of first and second magnetic materials 45B and 46B are the same as those of the first magnetic sensing unit 41A, the first power generation unit 42A, and the first set of first and second magnetic materials 45A and 46A, respectively, and their description is omitted. The second magnetic sensing unit 41B, the second power generation unit 42B, and the portion of the first and second magnetic materials 45B and 46B on the side of the second magnetic sensing unit 41B are housed in a case 43B. Terminals 42Ba and 42Bb are provided on the case 43B. The power generated by the second power generation unit 42B can be extracted to the outside of the second electrical signal generation unit 31B via terminals 42Ba and 42Bb. At least a portion of the magnetic sensing unit (for example, the first magnetic sensing unit 41A and the second magnetic sensing unit 41B) is arranged spaced apart on the outside of the magnet 11 in the radial direction or parallel direction of the magnet 11. For example, if the surfaces of the magnet 11 perpendicular to the rotation axis SF (i.e., surfaces in which multiple polarities of the magnet are arranged) are considered as one surface and the other surface, the magnetic sensing unit is arranged perpendicular to one or the other surface of the magnet 11 and spaced apart on the outside of the side surface of the magnet 11 along the direction of movement of the magnet (or a side surface parallel to the axial direction of the rotation axis SF).

[0033] The magnetic detection unit 12 includes magnetic sensors 51 and 52. Magnetic sensor 51 is positioned at an angle greater than 0° and less than 180° relative to the second magnetic sensing unit 41B (second electrical signal generating unit 31B) in the rotational direction of the rotating shaft SF. Magnetic sensor 52 is positioned at an angle greater than 22.5° and less than 67.5° relative to magnetic sensor 51 in the rotational direction of the rotating shaft SF (approximately 45° in Figure 2(B)).

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

[0035] Next, the operation of the first electrical signal generating unit 31A of this embodiment will be described. In the following description, the first magnetic sensing part 41A and the first power generating part 42A of the first electrical signal generating unit 31A in Figure 2(B) will be described collectively as the magnetic sensing member 47. The length direction of the magnetic sensing member 47 is the same as the length direction of the first magnetic sensing part 41A, and the center of the magnetic sensing member 47 in the length direction is the same as the center of the first magnetic sensing part 41A in the length direction. Note that the operation of the second electrical signal generating unit 31B is the same as that of the first electrical signal generating unit 31A, so its description will be omitted.

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

[0037] Furthermore, the magnetic-sensitive member 47 (or magnetic-sensitive part) is positioned near the outer surface of the magnet 11 such that its length is parallel to the surface (one side or the back side) of the flat magnet 11. In Figure 3(A), if the length of the magnetic-sensitive member 47 is denoted as direction LD1, then the length direction LD1 is parallel to the surface of the magnet 11. In this embodiment, the length direction LD1 of the magnetic-sensitive member 47 is substantially parallel to the θ direction (circumferential direction) and substantially perpendicular to the axial direction AD1, which is the magnetization direction of the magnet 11 (for example, a specific direction in which the orientation of the magnetic poles is fixed). Moreover, as shown in Figure 3(C), the length of the magnetic-sensitive member 47 is positioned substantially perpendicular to the tangential direction (here, the direction parallel to the axial direction AD1) of the magnetic field line MF1 of the magnet 11 that passes through the approximate center of the length of the magnetic-sensitive member 47 (for example, at a position half the length of the magnetic-sensitive member 47 or magnetic-sensitive parts 41A, 41B) in the length direction of the magnetic-sensitive member 47. Furthermore, the length LD1 of the magnetic-sensitive member 47 is arranged to be approximately perpendicular to the thickness direction which is perpendicular to the θ direction. In addition, the first and second magnetic materials 45A and 46A guide magnetic field lines from two parts of the magnet 11 with different polarities (for example, the north pole 16A and the south pole 17A) that are at the same angular position in the θ direction to the length LD1 of the magnetic-sensitive member 47 via one end 47a and the other end 47b of the magnetic-sensitive member 47.

[0038] The magnetic field components in the electrical signal generation unit 31A that are unnecessary for pulse generation, including the magnetic field lines generated on the side surface of the magnet 11, are perpendicular to the longitudinal direction of the magnetic-sensitive member 47. These unnecessary magnetic field components do not adversely affect the generation of magnetic domain walls from one end to the other of the magnetic-sensitive member 47 due to the large Barkhausen jump (Wiegand effect) in the longitudinal direction of the magnetic-sensitive member 47, which is caused by the reversal of the AC magnetic field due to the rotation of the magnet 11. Therefore, even if the magnetic-sensitive member 47 is placed near the magnet 11 and the electrical signal generation unit 31A is miniaturized, the electrical signal generation unit 31A can efficiently generate stable, high-output pulses using the electrical signal generation unit 31A by reversing the axial AC magnetic field due to the rotation of the magnet 11, without being affected by these unnecessary magnetic field components.

[0039] Figure 4 shows the circuit configuration of the power supply system 2 and the multi-turn information detection unit 3 of the encoder device EC according to this embodiment. In Figure 4, the power supply system 2 comprises a first electrical signal generation unit 31A, a rectifier stack 61, a second electrical signal generation 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 Figure 1.

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

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

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

[0043] Switch 64 has its first terminal 64a connected to the input terminal 63b and its second terminal 64b connected to the output terminal 63c. Regulator 63 uses an enable signal 7B supplied from buffer circuit 74 (electrical signal generation units 31A, 31B) to control terminal 63a as a control signal to switch between the conductive state and the isolated state between the first terminal 64a and the second terminal 64b of switch 64. For example, switch 64 includes a switching element such as MOS, TFT, or FET, with the first terminal 64a and the second terminal 64b being the source electrode and drain electrode, and the gate electrode connected to control terminal 63a. Switch 64's gate electrode is charged by the electrical signal (power) generated by the electrical signal generation units 31A, 31B, and when the potential of the gate electrode exceeds a threshold, it enters a conductive state (on state) between the source electrode and the drain electrode. Note that switch 64 may be provided outside of regulator 63, for example, as an external relay.

[0044] Furthermore, the AND gate 72 outputs a signal 7E (second signal) to the delay gate 73, which becomes high level when the enable signal 7B is high level and the output signal of the regulator 63 is above a predetermined threshold (high level). The delay gate 73 supplies a reset signal 7R, generated using signal 7E, to the counter 67 and the non-volatile memory 68. The reset signal 7R becomes high level after a predetermined delay time following the input signal 7E becoming high level, and then becomes low level when signal 7E becomes low level. The reset signal 7R can also be considered as a second signal equivalent to signal 7E. The counter 67 and the non-volatile memory 68 stop counting operation during the period when the reset signal 7R is low level. The stopping of counting operation by the counter 67 and the non-volatile memory 68 is hereafter referred to as initializing or resetting the counter 67 and the non-volatile memory 68. The signal relay circuit 75 is composed of the buffer circuit 74, the AND gate 72, and the delay gate 73.

[0045] The multi-turn information detection unit 3 includes magnetic sensors 51 and 52, and analog comparators 65 and 66 as a 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 multi-turn information detection unit 3 also includes a counter 67 as a detection unit 13 as shown in Figure 1, and a non-volatile memory 68 as a 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 Figure 2(C) and the 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 its output terminal 65b that is H level when the output voltage of the magnetic sensor 51 is above a threshold and L level when the output voltage is below the threshold. Alternatively, the analog comparator 65 may be configured to have two input terminals, and the output terminals 51a and 51b of the magnetic sensor 51 shown in Figure 2(C) may be connected to these two input terminals, allowing the analog comparator 65 to compare the voltages of 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 terminal 52p and ground terminal 52g of the magnetic sensor 52 are connected to the power 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 terminal 66p and ground terminal 66g of the analog comparator 66 are connected to the power line PL and the ground line GL, respectively. The output terminal 66b of the analog comparator 66 is connected to the second input terminal 67b of the counter 67. The analog comparator 66 outputs a signal from its output terminal 66b that is H level when the output voltage of the magnetic sensor 52 is above a threshold and L level when the output voltage is below the threshold.

[0047] The counter 67 counts the multi-turn information of the rotating shaft SF using power supplied from the battery 32. The counter 67 includes, for example, a CMOS logic circuit. The counter 67 operates using power supplied via the power terminal 67p connected to the power line PL and the 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 writing to the non-volatile memory 68 are completed, the counter 67 sets the discharge signal 7D to the H level to conduct the switching element 70 and discharges the charge stored in the capacitor 69A, thereby discharging the electrical signal generation units 31A and 31B (reducing the level of the WW output 7A). As a result, the enable signal 7B becomes L level and the regulator 63 turns off. In the following, discharging the electrical signal generation units 31A and 31B will also be referred to as resetting the WW output 7A.

[0048] The non-volatile memory 68 stores (performs a write operation) at least a portion of the rotational position information detected by the detection unit 13 (e.g., multi-turn information) using power supplied from the battery 32. The non-volatile memory 68 stores the counting result (multi-turn information) by the counter 67 as the rotational position information detected by the detection unit 13. The power terminal 68p and ground terminal 68g of the non-volatile memory 68 are connected to the power line PL and the ground line GL, respectively. The counter 67 and the non-volatile memory 68 stop counting operations and writing operations to the memory unit during the period when the reset signal 7R output from the delay circuit 73 is at the L level. Furthermore, the counter 67 and the non-volatile memory 68 perform counting operations and write to or read from the memory unit during the period when the voltage of the power line PL is above a predetermined threshold and the reset signal 7R is at the 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 it takes for the voltage of the power line PL to exceed a predetermined threshold and for the magnetic detection unit 12 and the counter 67 to operate accurately. The storage unit 14 in Figure 1 includes a non-volatile memory 68 and can retain information written while power is supplied, even when power is not supplied.

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

[0050] When the output capacitor 69C is empty, the regulator 63 needs to be charged when it is turned on during intermittent operation by the electrical signal generation units 31A and 31B, causing a momentary drop in the battery voltage 32. After the output capacitor 69C is charged, the battery voltage 32 recovers, 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 to set the reset signal 7R to a low level. However, in this configuration, if the rotating shaft SF rotates at high speed and the interval in which the regulator 63 turns on becomes shorter, the next WW output 7A will rise and the regulator 63 will turn on before the battery voltage 32 has fully recovered, causing the battery voltage 32 to gradually drop, the voltage of the power line PL to constantly be below the threshold, and there is a risk that the magnetic detection unit 12, etc., will not be able to operate accurately. Furthermore, the time it takes for the battery voltage 32 to recover becomes even more pronounced when the internal resistance of the battery 32 increases. In contrast, in this embodiment, after the counting operation in the counter 67 is completed, the switching element 70 discharges the WW output 7A of the electrical signal generation units 31A and 31B, so that even when the rotating shaft SF rotates at high speed, the voltage of the power line PL is reliably at a high level (details will be described later).

[0051] The battery 32 also includes a primary battery 36, such as a button cell battery, and a rechargeable secondary battery 37. The secondary battery 37 is electrically connected to the power supply unit MCE of the motor control unit MC. The power supply unit MCE drives the motor M in Figure 1 with power obtained from, for example, an AC power source (not shown), and can supply a DC voltage obtained from that power to the secondary battery 37 of the battery 32. During the period when the power supply unit MCE of the motor control unit MC can supply power (for example, the period when the main power 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 the period when the power supply unit MCE of the motor control unit MC cannot supply power (for example, the period when the main power is OFF), the supply of power from the power supply unit MCE to the secondary battery 37 is cut off.

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

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

[0054] The power switch 38 selects, for example, the battery that supplies power to the position detection system 1, based on the remaining charge of the secondary battery 37, to be either the primary battery 36 or the secondary battery 37. For example, if the remaining charge of the secondary battery 37 is above a threshold, the power switch 38 supplies power from the secondary battery 37 and does not supply power from the primary battery 36. This threshold is set based on the power consumed by the position detection system 1, and is set to be above the power that should be supplied to the position detection system 1, for example. For example, if the power switch 38 can cover the power consumed by the position detection system 1 with power from the secondary battery 37, it supplies power from the secondary battery 37 and does not supply power from the primary battery 36. Also, if the remaining charge of the secondary battery 37 is below the threshold, the power switch 38 does not supply power from the secondary battery 37 and supplies power from the primary battery 36. The power switch 38 may also function as a charger that controls the charging of the secondary battery 37, and it may use information about the remaining charge of the secondary battery 37 used for charging control to determine whether the remaining charge of the secondary battery 37 is above a threshold.

[0055] By using the secondary battery 37 in this manner, the depletion of the primary battery 36 can be slowed down. Therefore, the encoder device EC requires no maintenance (e.g., replacement) of the battery 32, or requires infrequent maintenance. The battery 32 only needs to include at least one of a primary battery 36 and a secondary battery 37. In the above embodiment, power is supplied selectively from either the primary battery 36 or the secondary battery 37, but power may be supplied in parallel from both the primary battery 36 and the secondary battery 37. For example, depending on the power consumption of each processing unit of the position detection system 1 (e.g., magnetic sensor 51, counter 67, non-volatile memory 68), the processing unit powered by the primary battery 36 and the processing unit powered by the secondary battery 37 may be determined. The secondary battery 37 only needs to 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 generation units 31A and 31B.

[0056] Next, the normal basic operation of the power supply system 2 and the multi-turn information detection unit 3 will be described. Figure 5 is a timing chart showing the operation of the multi-turn information detection unit 3 when the rotating shaft SF rotates counterclockwise (forward rotation). The timing chart showing the operation of the multi-turn information detection unit 3 when the rotating shaft SF rotates counterclockwise (reverse rotation) is the same as the chart in Figure 4, but reversed over time, so its explanation will be omitted.

[0057] In Figure 5, under "Magnetic Field," the solid line indicates the magnetic field at the position of the first electrical signal generation unit 31A, and the dashed line indicates the magnetic field at the position of the second electrical signal generation unit 31B. "First Electrical Signal Generation Unit" and "Second Electrical Signal Generation Unit" represent the output of the first electrical signal generation unit 31A and the output of the second electrical signal generation unit 31B, respectively. An output of current flowing in one direction is considered positive (+), and an output of current flowing in the opposite direction is considered negative (-). "Enable Signal" represents the enable signal 7B (potential) applied to the control terminal 63a of the regulator 63 by the electrical signals generated by the electrical signal generation units 31A and 31B. High levels are represented by "H" and low levels by "L". "Regulator Output" represents the output of the regulator 63 (potential of the power line PL). High levels are represented by "H" and low levels by "L".

[0058] In Figure 5, "Magnetic field on the first magnetic sensor" and "Magnetic field on the second magnetic sensor" represent the magnetic fields formed on magnetic sensors 51 and 52. The magnetic field formed by magnet 11 is shown by a long dashed line, the magnetic field formed by bias magnet is shown by a short dashed line, and the combined magnetic field is shown by a solid line. "First magnetic sensor" and "Second magnetic sensor" show the output when magnetic sensors 51 and 52 are continuously driven, respectively. The output from the first output terminal is shown by a dashed line, and the output from the second output terminal is shown by a solid line. "First analog comparator" and "Second analog comparator" show the output from analog comparators 65 and 66, respectively. The output when the magnetic sensor and analog comparator are continuously driven is shown under "Continuous drive," and the output when the magnetic sensor and analog comparator are intermittently driven is shown under "Intermittent drive."

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

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

[0061] Furthermore, the output of the magnetic sensor 52 is a positive sine wave in the range of angular positions from 157.5 to 247.5°. Within 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 angular positions of 180° and 225°, respectively. The signal output from the analog comparator 66 (hereinafter referred to as the B-phase signal) is maintained at an L level when no power is supplied, and becomes an H level at angular positions of 180° and 225°, respectively.

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

[0063] The counter 67 stores the signal level pair in the non-volatile memory 68 when one or both of the detected A-phase signal and B-phase signal are at the H level. When one or both of the A-phase signal and B-phase signal are next detected at the H level, the counter 67 reads the previous level pair from the non-volatile memory 68 and compares it with the current level pair to determine the rotation direction of the rotating shaft SF.

[0064] For example, if the previous signal level set was (H, H) and the current signal level set is (H, L), then the angular position was 225° in the previous detection and 270° in the current detection, indicating counterclockwise (forward rotation). The counter 67 supplies an up signal to the non-volatile memory 68 to indicate that it should increment the counter if the current level set is (H, L) and the previous level set was (H, H). When the non-volatile memory 68 detects the up signal from the counter 67, it updates the stored multi-turn information to a value that is 1 higher. In the case of reverse rotation, the counter 67 supplies a down signal to the non-volatile memory 68 to indicate that it should increment the counter. At this time, the non-volatile memory 68 updates the stored multi-turn information to a value that is 1 lower. In this way, the multi-turn information detection unit 3 according to this embodiment can detect multi-turn 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 of the encoder device EC of this embodiment is rotated at high speed will be described with reference to the flowchart in Figure 6 and the waveform diagram in Figure 7. When the rotating shaft SF is rotated at high speed, the period TE of the enable signal in Figure 5 becomes shorter. First, in step 102 of Figure 6, the WW output 7A of the electrical signal generation unit 31A or 31B in Figure 4 is generated, and the enable signal 7B of the buffer circuit 74 (see Figure 7(C)) becomes high. The WW output 7A is generated intermittently in short periods as shown in Figure 7(A), but the operation within one period of the WW output 7A will be described below as shown in Figures 7(B) to (E). Also, the signals generated by the electrical signal generation units 31A and 31B are pulsed as shown in Figure 5, but because a capacitor 69A is provided between the output terminals 61c and 62c and the ground wire 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 line PL connected to the output terminal 63c of the regulator 63 rises as shown by the dotted waveform (see Figure 7(B)). At this time, the signal 7E of the AND circuit 72 becomes high.

[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 Figure 7(B)), and in step 108, the counter 67 and the non-volatile memory 68 start operating. In step 110, the counter 67 writes rotation information (the up signal or down signal mentioned above) to the non-volatile memory 68. The data 7RD in Figure 7(B) shows an example of a signal exchanged between the counter 67 and the non-volatile memory 68. Then, in step 112, the counter 67 sets the discharge signal 7D to H level (see Figure 7(E)), and in response, the switching element 70 conducts and the WW output 7A decreases (discharges), 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 Figure 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 becomes L level (see Figure 7(B)), 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, as shown in Figure 7(A), even if each pulse signal of the WW output 7A is generated intermittently with a short period, the potential of the power line PL connected to the output terminal of the regulator 63 (dotted curve) hardly drops by resetting the WW output 7A and turning off the regulator 63 each time the counter 67 finishes processing. Therefore, 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 can be suppressed, and the voltage of the battery 32 can be reliably restored to its original voltage. Consequently, even when the rotating shaft SF is rotating at high speed, the supply and interruption of power from the battery 32 to the position detection system 1 (multi-turn information detection unit 3) can be accurately controlled, reducing the power consumption of the battery 32 and enabling highly accurate determination of the rotation information of the rotating shaft SF. This eliminates or reduces the frequency of maintenance (e.g., replacement) of the battery 32.

[0068] As described above, the encoder device EC according to this embodiment includes a position detection system 1 (position detection unit) that detects the rotational position information of the rotating shaft SF (moving part), a magnet 11 that rotates due to the rotation (movement) of the rotating shaft SF, an electrical signal generation unit 31A (electrical signal generation unit) that generates a WW output 7A (electrical signal) due to the change in the magnetic field caused by the rotation of the magnet 11, and a signal relay circuit 5 (circuit unit) that outputs a WW output 7A or an enable signal 7B (first signal) output from the electrical signal generation unit 31A to the position detection system 1 by discharging the charge stored in the capacitor 69A with 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 electrical signal generation unit 31A is discharged by the discharge signal 7D (reducing the WW output 7A), and the regulator 63 is turned off, thereby preventing further power consumption of the battery 32. Furthermore, since the output of the electrical signal generation unit 31A is discharged rather than the output of the regulator 63, the decrease in the output of the regulator 63 (the potential of the power supply for the position detection system 1) can be suppressed. As a result, when the rotating shaft SF rotates at high speed, the amount of charge from the regulator 63 to the position detection system 1 each time a WW output 7A (pulse signal) is generated can be reduced, the amount of voltage drop in the battery 32 can be reduced, and the time it takes for the battery 32 to recover voltage can be shortened. Therefore, even when the rotating shaft SF is rotating at high speed, power consumption of the battery 32 can be reduced, power can be supplied to the position detection system 1, and rotation information of the rotating shaft SF can be obtained with high accuracy.

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

[0071] Furthermore, the signal relay circuit 75 outputs a reset signal 7R (a second signal equivalent to signal 7E) via the WW output 7A after the potential of the power line PL of the position detection system 1 drops, to the counter 67 and non-volatile memory 68 of the position detection system 1. The counter 67 and non-volatile memory 68 are initialized by the reset signal 7R (they stop counting). This prevents malfunctions caused by unstable signals due to the drop in potential. Furthermore, according to this embodiment, the magnetic field components that are unnecessary for pulse generation in the electrical signal generation unit 31A, including the magnetic field lines generated on the side surface of the magnet 11, are perpendicular to the longitudinal direction of the magnetic-sensitive member 47. These unnecessary magnetic field components do not adversely affect the generation of magnetic domain walls extending from one end to the other in the longitudinal direction of the magnetic-sensitive member 47 due to the reversal of the AC magnetic field caused by the rotation of the magnet 11. Therefore, even if the magnetic-sensitive member 47 is placed near the magnet 11 and the electrical signal generation unit 31A is miniaturized, the electrical signal generation unit 31A can be used to efficiently generate a high-output WW output 7A (pulse signal) with high reliability (stable output) by reversing the axial AC magnetic field caused by the rotation of the magnet 11, without being affected by these unnecessary magnetic field components.

[0072] Furthermore, in the encoder device EC, power is supplied from the battery 32 to the multi-turn information detection unit 3 shortly after an electrical signal is generated in the electrical signal generation unit 31A, causing the multi-turn information detection unit 3 to be dynamically driven (intermittently driven). After the detection and writing of the multi-turn information is completed, the power supply to the multi-turn information detection unit 3 is cut off, but the count value is retained as it is stored in the storage unit 14. This sequence is repeated each time a predetermined position on the magnet 11 passes near the electrical signal generation unit 31A, even when the external power supply is cut off. The multi-turn information stored in the storage unit 14 is read out to the motor control unit MC, etc., when the motor M is next started, and is used to calculate the initial position of the rotation axis SF, etc. In this encoder device EC, the battery 32 supplies at least a portion of the power consumed by the position detection system 1 in response to the electrical signal generated by the electrical signal generation unit 31A, thus extending the lifespan of the battery 32. Therefore, maintenance (e.g., replacement) of the battery 32 can be eliminated or the frequency of maintenance can be reduced. For example, if the lifespan of the battery 32 is longer than that of other parts of the encoder device EC, it may be possible to eliminate the need to replace the battery 32.

[0073] Incidentally, by using a magnetically sensitive wire such as a Wiegant wire, a pulse current (electrical signal) can be obtained from the electrical signal generation unit 31A even when the rotation of the magnet 11 is extremely slow. Therefore, even when the rotation of the rotating shaft SF (magnet 11) is extremely slow, such as when no power is supplied to the motor M, the output of the electrical signal generation unit 31A can be used as an electrical signal. Amorphous magnetostrictive wire can also be used as the magnetically sensitive wire (first magnetically sensitive part 41A). In this case, for example, the encoder device EC may be configured to full-wave rectify the electrical signals (currents) generated from the electrical signal generation units (e.g., 31A, 31B) using the rectifier stack (e.g., rectifier) ​​described above, and supply the rectified power to the multi-turn information detection unit 3, etc.

[0074] [Second Embodiment] A second embodiment will be described with reference to Figures 8 to 10. In Figures 8, 9, and 10, parts corresponding to those in Figures 4, 6, and 7 are denoted by the same reference numerals, and their detailed descriptions are omitted. Figure 8 shows the encoder device ECA according to this embodiment. In Figure 8, an OR circuit 71 having three inputs is provided instead of the buffer circuit 74 in Figure 4. The WW output 7A generated at the output terminals 61c and 62c of the rectifier stacks 61 and 62 connected to the electrical signal generation units 31A and 31B is supplied to the first input of the OR circuit 71. In addition, a switching signal 7ND indicating the switching between normal operation and backup operation is supplied from the power supply unit MCE of the motor control unit MC to the second input of the OR circuit 71 and the switching signal input of the counter 67. Furthermore, a processing completion signal 7TC indicating the end of the counting operation is supplied from the counter 67 to the 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 is at a high level, the output of the OR circuit 71 becomes high level. When all of the WW output 7A, the switching signal 7ND, and the processing completion signal 7TC are at a low level, the output of the OR circuit 71 becomes low level. The output of the OR circuit 71 is supplied as an enable signal 7B to the first input of the AND circuit 72 and the 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 the signal relay circuit 75A.

[0075] The power supply unit MCE, in principle similar to the first embodiment, drives the motor M in Figure 1 with power obtained from, for example, an AC power source (not shown), and supplies the DC voltage obtained from that power to the secondary battery 37 of the battery 32. Furthermore, in this embodiment, as an example, in normal operation, the power supply unit MCE sets the switching signal 7ND to the H level, supplies the DC voltage to the secondary battery 37 of the battery 32, and the power from the secondary battery 37 is supplied to the input terminal 63b of the regulator 63 via the power switch 38. At this time, since the enable signal 7B of the OR circuit 71 is at the H level, the regulator 63 remains continuously ON, and the potential of the power line PL remains at the H level. As a result, the magnetic detection unit 12, the counter 67, and the non-volatile memory 68 operate continuously. 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 because the switching signal 7ND is at the H level. In this case, the counter 67, for example, takes the output of the analog comparators 65 and 66 at a predetermined sampling rate to obtain multi-turn rotation information of the rotating shaft SF, and writes the obtained information to the non-volatile memory 68.

[0076] In backup operation, for example, the power supply unit MCE (main power) is turned off, the motor M (rotating shaft SF) in Figure 1 is stopped, and the power supply 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 system has switched from normal operation to backup operation. In backup operation, in order to suppress the power consumption of the battery 32, the regulator 63 is turned on during the period when the WW output 7A of the electrical signal generation units 31A and 31B is above 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 transitioning from normal operation to backup operation, there is a risk that power may not be supplied to the magnetic detection unit 12, etc., at the moment 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, etc. Note that during normal operation, for example, the processing completion signal 7TC may always be at H level. After that, after rotation information is obtained, the counter 67 sets the switching signal 7ND to L level. After this, it is possible to smoothly transition to the backup operation described above. The configuration of this embodiment other than this is the same as in the first embodiment, so its explanation is omitted.

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

[0079] First, in step 120 of Figure 9, the power supply unit MCE (main power) is turned off, and the switching signal 7ND becomes L level (see Figure 10(A)). Accordingly, in step 122, the counter 67 sets the processing completion signal 7TC to H level (see Figure 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 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 Figure 10(C)), in step 108 the counter 67 and non-volatile memory 68 start operating, and in step 110 the counter 67 writes the rotation information (the up signal or down signal mentioned above) to the non-volatile memory 68. This completes the backup of rotation information when the power is off.

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

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

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

[0083] Furthermore, the method of using the encoder device ECA according to 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) until power is supplied from the regulator 63 with a WW output of 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, for example, the regulator 63 is turned on by the processing completion signal 7TC of the counter 67, and power is supplied to the magnetic detection unit 12 of the position detection system 1, and the rotation information of the rotating shaft SF is obtained and stored. Therefore, even if the power supply unit MCE is turned off, the system can smoothly transition to an intermittent operation sequence in which the operation of the regulator 63 is controlled using the WW output 7A of the electrical signal generation unit 31A after the rotation information of the rotating shaft SF at that time has been accurately obtained and stored. Furthermore, the electrical signal generation unit 31A has a magnetic sensor 41A whose magnetic properties change in response to changes in the magnetic field accompanying the rotation of the magnet 11, and generates a WW output 7A based on the magnetic properties of the magnetic sensor 41A. It is equipped with a signal relay circuit 75A (signal output section) and activates the regulator 63 when the power supply unit MCE is turned off 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 magnetic sensor 41A and the signal relay circuit 75A are the same as in the first embodiment.

[0084] In this embodiment, since the counter 67 outputs a processing completion signal 7TC to activate the regulator 63, the outputs of the electrical signal generation units 31A and 31B can be used smoothly. Note that the element that outputs the processing completion signal 7TC does not necessarily have to be the counter 67. Furthermore, in each of the embodiments described above, as shown in Figure 3(A), the tips of the first and second magnetic materials 45A and 46A of the electrical signal generating unit 31A are positioned near parts of opposite polarity at the same angular position on the surface (N pole 16A to S pole 16D) and back surface (S pole 17A to N pole 17D) of the magnet 11, so that the electrical signal generating unit 31A can be further miniaturized. Alternatively, as shown in the modified electrical signal generating unit 31C in Figures 3(D) and (E), the tip of the first magnetic material 45C on one end of the magnetic sensing member 47 may be positioned near a part of the surface of the magnet 11 with a certain polarity (e.g., N pole 16A or S pole 16B), and the tip of the second magnetic material 46C on the other end of the magnetic sensing member 47 may be positioned near a part of the surface of the magnet 11 with a different polarity (e.g., S pole 16D or N pole 16A). In this case, the first and second magnetic materials 45C and 46C guide magnetic field lines from two parts of the magnet 11 with different polarities (e.g., N pole 16A and S pole 16D) that are located at different positions in the direction of rotation, along the length of the magnetic-sensitive member 47. In the electrical signal generation unit 31C, the magnetic circuit MC2 is formed so that it passes from the magnet 11 through the first magnetic material 45C, the magnetic-sensitive member 47, and the second magnetic material 46C. As a result, the magnetic-sensitive member 47 can efficiently output stable pulses due to the reversal of the AC magnetic field caused by the rotation of the magnet 11, without being affected by unwanted magnetic fields on the sides of the magnet 11. The configuration of the magnet 11 and the configuration of the electrical signal generation units 31A and 31B are arbitrary.

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

[0086] In the first embodiment described above, the magnet 11 is an 8-pole magnet having 4 poles in the circumferential direction and 2 poles in the thickness direction, but the configuration is not limited to this and can be modified as appropriate. For example, the magnet 11 may have 2 or 4 or more poles in the circumferential direction. In the above embodiment, the position detection system 1 detects the rotational position information of the rotating shaft SF (moving part) as position information, but it may also detect at least one of the position, velocity, and acceleration in a predetermined direction as position information. The encoder devices EC and ECA may include a rotary encoder or a linear encoder. Furthermore, in the encoder devices EC and ECA, the power generation unit and the detection unit may be provided on the rotating shaft SF, and the magnet 11 may be provided outside the moving body (e.g., the rotating shaft SF), so that the relative position between the magnet and the detection unit changes with the movement of the moving part. In addition, the position detection system 1 does not need to detect multi-rotation information of the rotating shaft SF; multi-rotation information may be detected by a processing unit outside the position detection system 1.

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

[0088] Furthermore, the electrical signal generation units 31A and 31B may supply at least a portion of the power consumed by the position detection system 1. For example, the electrical signal generation units 31A and 31B may supply power to the processing unit of the position detection system 1 that has relatively low power consumption. Also, the power supply system 2 does not have to supply power to a part of the position detection system 1. For example, the power supply system 2 may intermittently supply power to the detection unit 13 but not to the storage unit 14. In this case, the storage unit 14 may be supplied intermittently or continuously from a power source, battery, etc., provided outside the power supply system 2. The power generation unit may generate power through phenomena other than the Great Barkhausen jump, and for example, it does not have to supply power to the moving part (e.g., the rotating axis SF) and a part of the position detection system 1. For example, the power supply system 2 may intermittently supply power to the detection unit 13 but not to the storage unit 14. In this case, power may be supplied to the storage unit 14 intermittently or continuously from a power source, battery, or the like, located outside the power supply system 2. The power generation unit may generate power through phenomena other than the Great Barkhausen jump, for example, by electromagnetic induction due to changes in the magnetic field accompanying the movement of the moving part (e.g., the rotating shaft SF). The storage unit that stores the detection results of the detection unit may be located outside the position detection system 1, or outside the encoder devices EC and ECA.

[0089] [Drive system] An example of a drive device will be described. Figure 11 shows an example of a drive device MTR. In the following description, components that are the same as or equivalent to those in the embodiments described above will be denoted by the same reference numerals, and their descriptions will be omitted or simplified. This drive device MTR is a motor device including an electric motor. The drive device MTR has a rotating shaft SF, a main body (drive unit) BD that rotates the rotating shaft SF, and an encoder device EC that detects the 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 non-load-side end SFb. The load-side end SFa is connected to another power transmission mechanism such as a reduction gear. A scale S is fixed to the non-load-side end SFb via a fixing part. Along with the fixing of the scale S, an encoder device EC is attached. The encoder device EC is an encoder device according to the above-described embodiment, modification thereof, or combination thereof.

[0091] In this drive unit MTR, the motor control unit MC, shown in Figure 1, controls the main unit BD using the detection results from the encoder unit EC. Since the drive unit MTR requires little to no battery replacement for the encoder unit EC, maintenance costs can be reduced. Note that the drive unit MTR is not limited to a motor unit; it may also be other drive units having a shaft that rotates using hydraulics or pneumatics.

[0092] [Stage equipment] An example of a stage device will be described. Figure 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 rotating shaft SF of the drive device MTR shown in Figure 11. In the following description, components that are the same as or equivalent to those in the above-described embodiment will be given the same reference numerals, and their descriptions will be omitted or simplified.

[0093] The stage device STG drives the drive unit MTR to rotate the rotation shaft SF, and this rotation is transmitted to the rotary table TB. At this time, the encoder device EC detects the angular position of the rotation shaft SF. Therefore, the angular position of the rotary table TB can be detected by using the output from the encoder device EC. A reduction gear or the like may be placed between the load-side end SFa of the drive unit MTR and the rotary table TB.

[0094] The STG stage device reduces maintenance costs because it requires little to no battery replacement for the encoder device EC. The STG stage device can be applied, for example, to rotary tables in machine tools such as lathes. [Robot equipment] An example of a robotic device will be described. Figure 13 is a perspective view showing the robotic device RBT. Figure 13 schematically shows a part (joint portion) of the robotic device RBT. In the following description, components that are the same as or equivalent to those in the above-described embodiment will be given the same reference numerals, and their descriptions will be omitted or simplified. This robotic 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 comprises an arm portion 101, a bearing 101a, and a bearing 101b. The second arm AR2 comprises an arm portion 102 and a connecting portion 102a. The connecting portion 102a is positioned between the bearing 101a and the bearing 101b in the joint portion JT. The connecting portion 102a is integrally provided with the rotating shaft SF2. The rotating shaft SF2 is inserted into both the bearing 101a and the bearing 101b in 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 reduction gear RG.

[0096] The reducer RG is connected to the drive unit MTR and reduces the rotation of the drive unit MTR to, for example, 1 / 100th of its original speed before transmitting it to the rotating shaft SF2. Although not shown in Figure 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 robotic device RBT drives the drive unit 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 causes the connecting part 102a to rotate together, thereby causing the second arm AR2 to rotate relative to the first arm AR1. At this time, the encoder device EC detects the angular position of the rotating shaft SF, etc. Therefore, the angular position of the second arm AR2 can be detected from the output of the encoder device EC.

[0098] The RBT robotic system reduces maintenance costs because it eliminates or significantly reduces the need for battery replacement of the encoder unit EC. Furthermore, the RBT robotic system is not limited to the above configuration; the MTR drive unit can be applied to various robotic systems equipped with joints. Furthermore, the following embodiments of the invention are also described in this specification. 1) An encoder device comprising: a position detection unit for detecting position information of a moving part; a magnet that moves as a result of the movement of the moving part; an electrical signal generation unit that generates an electrical signal as a result of the change in the magnetic field caused by the movement of the magnet; and a circuit unit that outputs the output of the electrical signal generation unit, which changes according to a control signal from the position detection unit, to the position detection unit. 2) The encoder device according to claim 1, which has a storage unit that stores the charge output from the electrical signal generating unit, wherein the output of the electrical signal generating unit changes when the charge in the storage unit is discharged by the control signal. 3) The encoder device according to 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 generation unit, and the position detection unit is initialized by the electrical signal after the potential of the position detection unit has decreased. 4) The encoder device according to 3, further comprising a power supply unit that supplies power to the position detection unit based on the electrical signal, wherein the circuit unit outputs the electrical signal to the position detection unit after the potential of the position detection unit has decreased when the potential of the power supply unit is above a reference value. 5) The encoder device according to 4, wherein the circuit section includes a delay section that outputs the electrical signal to the position detection section after the potential of the position detection section has decreased after a predetermined time has elapsed since the potential of the power supply section has risen. 6) The encoder device according to any one of items 1 to 4, wherein the position detection unit outputs the control signal to change the output of the electrical signal generation unit when the position detection process of the moving unit is completed. 7) The encoder device according to any one of items 1 to 6, wherein the electrical signal is output intermittently and repeatedly by the movement of the moving part. 8) An encoder device comprising: a position detection unit that receives power from a power source to detect the position information of a moving part; a magnet that moves as a result of the movement of the moving part; an electrical signal generating unit that generates an electrical signal as a result of the 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 electrical signal, wherein the position detection unit detects the position information when the power supply from the power source is interrupted until power is supplied from the power supply unit using the electrical signal. 9) The encoder device according to 8, further comprising a circuit unit that, when the position information is detected by the position detection unit, outputs to the position detection unit an output from the electrical signal generation unit that is changed by a control signal from the position detection unit.

[0099] 10) The encoder device according to 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 generation 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 according to 10, wherein the circuit section is further comprising a delay section that outputs the electrical signal to the position detection section after the potential of the position detection section has decreased after a predetermined time has elapsed since the potential of the power supply section has risen. 12) An encoder device according to any one of items 8 to 11, wherein the electrical signal is output intermittently and repeatedly by the movement of the moving part. 13) The encoder device according to any one of claims 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, the position detection unit detects the position information based on the 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) The encoder device according to any one of claims 1 to 13, wherein the position detection unit includes a scale that moves by the movement of the moving unit, an illumination unit that irradiates light onto the scale, and a light detection unit that detects light from the scale. 15) The encoder device according to any one of items 1 to 7, wherein the moving part includes a rotating shaft, the magnet includes an annular or fan-shaped portion, and the electrical signal generating parts are arranged in a plurality along the magnet. 16) The encoder device according to 15, wherein the position detection unit comprises an angle detection unit for detecting angular position information of the rotation axis within one rotation, and a multi-rotation information detection unit for detecting multi-rotation information of the rotation axis as the position information. 17) A drive device comprising an encoder device as described in any one of items 1 to 16, and a power supply unit that supplies power to the moving part. 18) A stage apparatus comprising a movable object and a drive device described in 17 for moving the movable object. 19) A robotic device comprising a drive device as described in 17, and an arm that moves relative to the drive device. 20) A method for using an encoder device comprising: a position detection unit that detects the position information of a moving part when power is supplied from a power source; a magnet that moves due to the movement of the moving part; an electrical signal generating unit that generates an electrical 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 electrical signal, wherein the position detection unit detects the position information when the power supply from the power source is interrupted, until power is supplied from the power supply unit using the electrical signal. 21) The method of use according to 20, which includes the position detection unit obtaining the position information and storing it in the memory unit, and discharging the electrical signal when the power supply from the power source is interrupted. [Explanation of symbols]

[0100] 1…Position detection system, 3…Multi-turn information detection unit, 4…Angle detection unit, 11,11A…Magnet, 12…Magnetic detection unit, 13…Detection unit, 14…Storage unit, 21…Light-emitting element (Irradiation 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 material, 46A...Second magnetic material, 47...Magnetic sensor, 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...Rotating shaft, AR1...First arm, AR2...Second arm, MTR...Drive device, RBT...Robot device, STG...Stage device

Claims

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

2. It has a storage unit for accumulating the charge of the aforementioned electrical signal, The encoder device according to claim 1, wherein the electrical signal changes when the charge of the storage unit is discharged by the control signal.

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

4. The system includes a power supply unit that supplies the power to the second input based on the electrical signal, The encoder device according to claim 3, wherein the circuit unit outputs the electrical signal to the first input after the potential of the second input has decreased when the potential of the power supply unit is above a reference value.

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

6. The encoder device according to claim 1, wherein the position detection unit outputs the control signal to change the electrical signal when it has finished processing the position information of the moving part.

7. The encoder device according to claim 1, wherein the electrical signal is output intermittently and repeatedly by the movement of the moving part.

8. The aforementioned moving part includes a rotating shaft, The aforementioned magnet includes ring-shaped or fan-shaped portions, The encoder device according to claim 1, wherein the electrical signal generating units are arranged in multiples along the magnet.

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

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

11. The encoder device according to claim 4, wherein the second input is supplied with power from the power supply unit and is not discharged by changes 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 part.

13. Moving objects and, A stage apparatus comprising a drive device according to claim 12 for moving the aforementioned moving object.

14. The drive device according to claim 12, A robotic device comprising an arm that moves relative to another by the aforementioned drive device.

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