Rotation angle detection device

Abstract

The present invention provides a rotation angle detection device that can be miniaturized while suppressing a decrease in the accuracy of rotation angle detection. [Solution] The rotation angle detection device 100 includes an excitation coil 30, a detection unit comprising a plurality of detection coils 41 to 44, which constitute an induction type sensor that detects changes in the magnetic field caused by the rotation of a rotating body 10 to which a magnetic field is applied by the excitation coil 30, by electromagnetic induction, and a substrate 70. Detection coils 41 and 43 are connected to each other, and detection coils 42 and 44 are connected to each other. Detection coils 41, 42, 43, and 44 are arranged side by side on the substrate 70 along the circumferential direction of the rotating body 10, and are formed such that the outer edges of adjacent coils overlap each other when viewed from a direction perpendicular to the main surface of the substrate 70.

Description

Technical Field

[0001] The present invention relates to a rotation angle detection device.

Background Art

[0002] Conventionally, rotation angle detection devices have been known (see, for example, Patent Document 1 and Patent Document 2).

[0003] Patent Document 1 describes a rotation angle detection sensor including a printed circuit board on which a coil is formed. This rotation angle detection sensor includes a rotating plate that rotates integrally with a shaft that is the rotation axis of a motor. The printed circuit board is arranged to face the rotating plate and is formed in an arc shape along the circumferential direction of the rotating plate. The coil formed on the printed circuit board is wound along the main surface of the board. This coil includes four coils for detecting the rotation angle that receive the magnetic field due to the rotation of the rotating plate and output an induced current. The four coils for detecting the rotation angle are arranged in a row in an arc shape along the circumferential direction on the board.

[0004] Patent Document 2 also describes a rotation angle detection device including a rotating body that rotates integrally with a shaft that is the rotation axis of a motor, and a detection unit that detects a change in the magnetic field due to the rotation of the rotating body. The detection unit includes four detection coils arranged in an arc shape along the circumferential direction of the rotating body on a board arranged to face the rotating body. In Patent Document 2, each of the four detection coils is formed as a coil pattern laminated in two layers, and has a portion wound on one side in the thickness direction of the board and a portion wound on the other side.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] In this case, when reducing the radial size in order to miniaturize the device, in the above-mentioned Patent Documents 1 and 2, the four detection coils are arranged in an arc shape along the circumferential direction of the rotating body, so the area on the substrate where the detection coils are arranged becomes smaller. As a result, the detection sensitivity decreases due to the reduced number of turns in each of the four detection coils, and the accuracy of rotation angle detection decreases. Therefore, it is desirable to miniaturize the device while suppressing the decrease in rotation angle detection accuracy.

[0007] This invention was made to solve the above-mentioned problems, and one of its objectives is to provide a rotation angle detection device that can be miniaturized while suppressing a decrease in the accuracy of rotation angle detection. [Means for solving the problem]

[0008] To achieve the above objective, a rotation angle detection device in one aspect of this invention comprises an excitation coil that applies a magnetic field to a rotating body by passing an alternating current through it; a detection unit that includes a plurality of detection coils and constitutes an induction type sensor that detects changes in the magnetic field due to the rotation of a rotating body to which a magnetic field has been applied by the excitation coil by electromagnetic induction; and a substrate on which a plurality of detection coils of the detection unit are formed. The plurality of detection coils include a first detection coil and a third detection coil connected to each other, and a second detection coil and a fourth detection coil connected to each other. The first detection coil, the second detection coil, the third detection coil, and the fourth detection coil are arranged in a line along the circumferential direction of the rotating body on the substrate, and are formed such that, when viewed from a direction perpendicular to the main surface of the substrate, the outer peripheral edges of at least one pair of adjacent coils overlap each other.

[0009] In a rotation angle detection device according to one aspect of this invention, as described above, the first detection coil, the second detection coil, the third detection coil, and the fourth detection coil are arranged side by side on the substrate along the circumferential direction of the rotating body, and are formed such that at least one pair of adjacent coils overlap each other when viewed from a direction perpendicular to the main surface of the substrate. As a result, since at least one pair of adjacent coils overlap each other when viewed from a direction perpendicular to the main surface of the substrate, the area on the substrate where the detection coils are arranged can be increased by the amount by which the outer edges of the coils overlap each other. Therefore, even when miniaturizing the device, it is possible to suppress a reduction in the number of turns of the multiple detection coils. As a result, miniaturization can be achieved while suppressing a decrease in the accuracy of rotation angle detection.

[0010] In the rotation angle detection device according to the first aspect described above, preferably, the detection unit detects changes in the magnetic field of a rotating body arranged in a motor, and each of the plurality of detection coils has a magnitude of an angle θ expressed by equation (2), where p is the number of poles of the motor and k is a real number greater than 1, when viewed from a direction perpendicular to the main surface of the substrate in the circumferential direction of the rotating body.

number

[0011] Here, the magnetic field applied to the rotating body by the excitation coil includes a periodic component that changes periodically in the circumferential direction of the rotating body. Therefore, if the magnitude of each of the multiple detection coils in the circumferential direction is smaller than one period of the periodic component of the magnetic field applied by the excitation coil, the accuracy of rotation angle detection will decrease due to the influence of the periodic component. Taking this into consideration, in the present invention, each of the multiple detection coils is configured to have a magnitude equal to the angle θ represented by the above equation (2) in the circumferential direction of the rotating body when viewed from a direction perpendicular to the main surface of the substrate. With this configuration, each of the multiple detection coils has a sufficiently large magnitude equal to an angle greater than one-quarter of one period of the electric angle of the motor in the circumferential direction, so that the magnitude of each of the multiple detection coils can be made larger than one period of the periodic component of the magnetic field applied by the excitation coil. As a result, it is possible to suppress the decrease in rotation angle detection accuracy due to the influence of the periodic component of the magnetic field applied by the excitation coil.

[0012] In the rotation angle detection device with the first surface described above, preferably, the substrate has a first layer, a second layer, a third layer, and a fourth layer arranged in order from the main surface opposite to the rotating body, the first detection coil and the third detection coil are each formed by laminating on the first and third layers, the second detection coil and the fourth detection coil are each formed by laminating on the second and fourth layers, and the first detection coil and the third detection coil have more turns than the second and fourth detection coils.

[0013] With this configuration, the first and third detection coils stacked in the first and third layers have more turns than the second and fourth detection coils stacked in the second and fourth layers. Therefore, the number of turns of the first and third detection coils, which are located at a relatively large distance from the rotating body, can be increased compared to the number of turns of the second and fourth detection coils, which are located at a relatively small distance from the rotating body. As a result, the difference between the detection sensitivity of the first and third detection coils and the detection sensitivity of the second and fourth detection coils can be reduced, thereby suppressing a decrease in the accuracy of rotation angle detection caused by the difference in detection sensitivity.

[0014] In the rotation angle detection device with the first surface described above, preferably, the substrate has a first layer, a second layer, a third layer, and a fourth layer arranged in order from the main surface opposite to the rotating body, the first detection coil and the third detection coil are each formed by lamination in the second and third layers, and the second detection coil and the fourth detection coil are each formed by lamination in the first and fourth layers.

[0015] With this configuration, the second and fourth detection coils are positioned in the first layer, which has the greatest distance from the rotating body, and the fourth layer, which has the smallest distance, respectively. The first and third detection coils are positioned in the second layer, which has the second largest distance from the rotating body, and the third layer, which has the second smallest distance. As a result, the difference between the average distance from the rotating body for the first and third detection coils and the average distance from the rotating body for the second and fourth detection coils can be reduced. Consequently, the difference between the detection sensitivity of the first and third detection coils and the detection sensitivity of the second and fourth detection coils can be reduced, thereby suppressing a decrease in the accuracy of rotation angle detection due to differences in detection sensitivity.

[0016] Furthermore, the following configuration is also possible for the rotation angle detection device based on the first aspect described above.

[0017] (Additional note 1) In the rotation angle detection device according to the above-described one aspect, the detection unit includes a first detection unit and a second detection unit each including a plurality of detection coils formed in a superimposed state, and each of the first detection unit and the second detection unit separately detects a change in magnetic field due to the rotation of the rotating body.

[0018] With this configuration, since the detection unit includes the first detection unit and the second detection unit that separately detect a change in magnetic field due to the rotation of the rotating body, the configuration for detecting a change in magnetic field due to the rotation of the rotating body can be made redundant. Therefore, even when an abnormality occurs in either one of the first detection unit and the second detection unit, a change in magnetic field due to the rotation of the rotating body can be detected by the other, so that the rotation angle can be continuously detected.

[0019] (Additional item 2) Further, in the rotation angle detection device according to the above-described one aspect, the substrate has a first layer, a second layer, a third layer, and a fourth layer arranged in order from the main surface on the opposite side of the rotating body, and each of the plurality of detection coils is formed by being laminated on any one of the first layer, the second layer, the third layer, and the fourth layer and has via portions connecting the laminated portions to each other, and at least one via portion of the plurality of detection coils is arranged at a position shifted from the coil center when viewed from a direction perpendicular to the main surface of the substrate.

[0020] With this configuration, since the via portions connecting the laminated portions to each other are arranged at positions shifted from the coil center when viewed from a direction perpendicular to the main surface of the substrate, even when the size in the circumferential direction of each of the plurality of detection coils is increased, it is possible to suppress the detection coils from physically interfering with the via portions. Therefore, the size in the circumferential direction of the plurality of detection coils can be made larger by the amount by which the via portions are shifted from the coil center, so that the number of turns of the plurality of detection coils can be made larger. As a result, a decrease in the detection accuracy of the rotation angle can be further suppressed.

Effect of the Invention

[0021] According to the present invention, as described above, miniaturization is possible while suppressing a decrease in the accuracy of rotation angle detection. [Brief explanation of the drawing]

[0022] [Figure 1] This is a schematic diagram showing the configuration of a motor control system equipped with a rotation angle detection device according to the first embodiment of the present invention. [Figure 2] This is a block diagram showing the configuration of the rotation angle detection device according to the first embodiment. [Figure 3] This is a schematic exploded perspective view showing the substrate on which the detection coil and excitation coil are located, and the rotating body. [Figure 4] This is a schematic perspective view illustrating the configuration of the detection coil. [Figure 5] This is a schematic top view illustrating the arrangement of the detection coil and the excitation coil. [Figure 6] This diagram illustrates the magnetic flux density caused by the magnetic field applied by the excitation coil. [Figure 7] This diagram illustrates the relationship between the superimposed magnetic field period and the size of the excitation coil. [Figure 8] This diagram illustrates the arrangement of multiple detection coils on a circuit board. [Figure 9] This figure illustrates the arrangement of detection coils in a rotation angle detection device according to a second embodiment of the present invention. [Figure 10] This figure illustrates the arrangement of detection coils in a rotation angle detection device according to a modified example of the present invention. [Modes for carrying out the invention]

[0023] Embodiments of the present invention will be described below with reference to the drawings.

[0024] [First Embodiment] The configuration of the rotation angle detection device 100 according to the first embodiment will be described with reference to Figures 1 to 8.

[0025] (Motor control system) As shown in Figure 1, the rotation angle detection device 100 is configured to detect the rotation angle of a motor 101 used as a drive source for vehicle operation, power windows, sliding doors, and shift-by-wire systems. The motor 101 includes a stator (not shown), a rotor (not shown), and a shaft 101a.

[0026] The motor 101 rotates the shaft 101a in the R direction, which is the rotational direction (circumferential direction), by being operated under the control of the ECU 102 (Electronic Control Unit). The ECU 102 provides feedback control of the motor 101's drive based on the rotation angle signal, which is a signal indicating the rotation angle of the motor 101a detected by the rotation angle detection device 100. The ECU 102 has a processor such as a CPU (Central Processing Unit) and a storage unit including ROM (Read Only Memory) and RAM (Random Access Memory). The motor control system is composed of the rotation angle detection device 100, the motor 101, and the ECU 102.

[0027] (Configuration of the rotation angle detection device) As shown in Figures 1 and 2, the rotation angle detection device 100 comprises a rotating body 10 and a detection unit 20. In the rotation angle detection device 100, the detection unit 20 detects changes in the magnetic field of the rotating body 10 which is placed on the motor 101, thereby configuring an inductive sensor (electromagnetic induction sensor) for detecting the rotation angle of the shaft 101a of the motor 101. The inductive sensor is an induction type sensor that detects changes in the magnetic field due to the rotation of the rotating body 10 by electromagnetic induction.

[0028] The rotating body 10 is configured to rotate integrally with the shaft 101a. The shaft 101a is the rotation axis of the motor 101, extending along the Z direction. The rotating body 10 is attached to the shaft 101a. The rotating body 10 is a plate-shaped member made of a magnetic material such as metal. The outer edge of the rotating body 10 is configured to have a sinusoidal shape (see Figures 3 and 5) with alternating peaks and valleys. For example, the rotating body 10 has four peaks and four valleys.

[0029] As shown in Figure 2, the detection unit 20 includes an excitation coil 30, a plurality of detection coils 40, and a sensor circuit unit 50. The detection coils 40 include four detection coils 41, detection coil 42, detection coil 43, and detection coil 44. The detection unit 20 detects the change in the magnetic field caused by the rotation of the rotating body 10 to which a magnetic field is applied by the excitation coil 30, by electromagnetic induction. That is, the detection unit 20 detects the rotation angle of the shaft 101a based on the change in the magnetic field. Detection coil 41 is an example of the "first detection coil" in the claims. Detection coil 42 is an example of the "second detection coil" in the claims. Detection coil 43 is an example of the "third detection coil" in the claims. Detection coil 44 is an example of the "fourth detection coil" in the claims.

[0030] In the first embodiment, the detection unit 20 includes a first detection unit 21 and a second detection unit 22. The first detection unit 21 and the second detection unit 22 each include an excitation coil 30, a detection coil 40 (detection coils 41-44), and a sensor circuit unit 50. Each of the first detection unit 21 and the second detection unit 22 separately detects changes in the magnetic field due to the rotation of the rotating body 10. That is, in the detection unit 20, the first detection unit 21, which is the first inductive sensor, and the second detection unit 22, which is the second inductive sensor, are configured separately from each other. As a result, in the rotation angle detection device 100, the detection unit 20, which is configured to detect the rotation angle, is redundant with the first detection unit 21 and the second detection unit 22. The detection unit 20 is arranged on a substrate 70. The substrate 70 is a common substrate on which the first detection unit 21 and the second detection unit 22 are arranged. The first detection unit 21 and the second detection unit 22 are arranged side by side on the substrate 70 along the circumferential R direction (see Figure 3). In the following description, the configuration and operation of the first detection unit 21 will be described, and the configuration and operation of the second detection unit 22 will not be described as they have the same configuration.

[0031] The excitation coil 30 is configured to generate an alternating magnetic field for detecting the rotation angle of the shaft 101a and to apply the generated magnetic field to the rotating body 10. Specifically, the excitation coil 30 is configured to be excited by alternating power supplied from the sensor circuit 50. When an alternating current is passed through the excited excitation coil 30, it is configured to generate a magnetic field (alternating magnetic field) that vibrates in the direction of the rotation axis (Z direction) of the rotation of the rotating body 10. The excitation coil 30 applies the generated alternating magnetic field toward the rotating body 10.

[0032] In the rotation angle detection device 100, an alternating magnetic field generated by the excitation coil 30 is applied to the rotating body 10, causing eddy currents to be generated in the rotating body 10. In the detection coil 40, an induced current flows due to the magnetic field generated by these eddy currents in the rotating body 10. The induced current flowing through the detection coil 40 is output to the sensor circuit unit 50 as a detection result. In other words, in the first embodiment, the detection coil 40 outputs a detection result indicating the change in the magnetic field detected in order to obtain the rotation angle of the rotating body 10. In the sensor circuit unit 50, a rotation angle signal indicating the rotation angle is generated based on the acquired detection result. The rotation angle detection device 100 outputs the rotation angle signal generated in the sensor circuit unit 50 to the ECU 102.

[0033] (Details of the detection unit configuration) As shown in Figure 3, the substrate 70 on which the detection unit 20 is located is positioned opposite the rotating body 10 on one side (Z1 direction side) in the direction in which the rotation axis of the rotating body 10 extends. The substrate 70 is a circular plate oriented along the R direction, which is the circumferential direction of rotation of the rotating body 10. The substrate 70 is, for example, a printed circuit board.

[0034] On the substrate 70, each of the excitation coil 30 and detection coils 41-44 of the detection unit 20 is formed as a coil pattern. That is, each of the excitation coil 30 and detection coils 41-44 is formed as a conductor pattern on the substrate 70. Each of the excitation coil 30 and detection coils 41-44 is formed on the substrate 70 as a coil pattern wound multiple times along the main surface of the substrate 70. The excitation coil 30 is formed on the substrate 70 as a coil pattern that surrounds a plurality of detection coils 40 (detection coils 41-44) in an arc shape. The four detection coils 41, 42, 43, and 44 are arranged in a line along the circumferential direction (R direction), which is the rotation direction of the rotating body 10, on the substrate 70. The four detection coils 41, 42, 43, and 44 are surrounded by the excitation coil 30 and are arranged in this order in an arc shape toward the R1 direction, which is one side of the circumferential direction.

[0035] As shown in Figure 4, detection coils 41 and 43 have different winding directions for their coil patterns. Similarly, detection coils 42 and 44 have different winding directions for their coil patterns. Detection coils 41 and 43 are connected in series with each other. Detection coils 42 and 44 are also connected in series with each other. In other words, in detection coil 40, coils with different winding directions are connected in series with each other. Note that in Figure 4, for simplification, detection coils 41, 42, 43, and 44, which are arranged in an arc shape on the substrate 70, are schematically shown as being arranged in a straight line.

[0036] Furthermore, on the substrate 70, the multiple detection coils 40 (detection coils 41 to 44) are formed as a multilayer coil pattern. One detection coil 41 has a portion 41a formed on one side (Z1 direction side) in the thickness direction which intersects the main surface of the substrate 70, and a portion 41b formed on the other side (Z2 direction side). The detection coil 41 is formed by portions 41a and 41b as a coil pattern stacked on the substrate 70 in the thickness direction (Z direction). For example, in portion 41a, a coil pattern wound counterclockwise toward the inside is formed. Also, in portion 41b, a coil pattern wound clockwise toward the inside is formed. That is, the detection coil 41 has two portions that are wound in different directions across two layers on the Z1 direction side and the Z2 direction side of the substrate 70. Note that the winding direction of the coil may be configured to be reversed from the above. Furthermore, the detection coil 41 has via portions 41c that connect the stacked portions (coil patterns) by connecting portions 41a and 41b. Portions 41a and 41b are connected to each other by the via portion 41c at the coil center C, which is the center of the wound coil pattern as viewed from the Z1 direction. The via portion 41c is a conductor that penetrates the substrate 70 in the thickness direction (Z direction) at the coil center C. Although portions 41a and 41b are wound in different directions, they are connected so that they have the same polarity when their central portions are connected.

[0037] The detection coils 42, 43, and 44, like the detection coil 41, have two portions wound in different directions across two layers of the substrate 70, one on the Z1 side and the other on the Z2 side, and a via portion connecting the two portions at the coil center C. Specifically, the detection coil 42 has a portion 42a on the Z1 side, a portion 42b on the Z2 side, and a via portion 42c. The detection coil 43 has a portion 43a on the Z1 side, a portion 43b on the Z2 side, and a via portion 43c. The detection coil 44 has a portion 44a on the Z1 side, a portion 44b on the Z2 side, and a via portion 44c. For example, portion 43a of the detection coil 43 is wound in a different direction from portion 41a of the detection coil 41, and portion 43b is wound in a different direction from portion 41b. Portions 41b and 43b are connected to each other.

[0038] Furthermore, portion 44a of the detection coil 44 is wound in a different direction from portion 42a of the detection coil 42, and portion 44b is wound in a different direction from portion 42b. Portions 42b and 44b are connected to each other. Note that adjacent detection coils 41 and 42 may be wound in the same direction or different directions. Similarly, adjacent detection coils 43 and 44 may be wound in the same direction or different directions.

[0039] In the first embodiment, the detection coils 41, 42, 43, and 44 are formed as a multilayer coil pattern, with the outer edges of adjacent coils overlapping each other when viewed from the Z1 direction, which is perpendicular to the main surface of the substrate 70. In the first embodiment, the outer edges of portions 42a and 42b of the detection coil 42 overlap the outer edges of portions 41a and 41b of the detection coil 41 on the R1 direction side. Similarly, the outer edges of portions 43a and 43b of the detection coil 43 overlap the outer edges of portions 42a and 42b of the detection coil 42 on the R2 direction side. Furthermore, the outer edges of portions 44a and 44b of the detection coil 44 overlap the outer edges of portions 43a and 43b of the detection coil 44 on the R2 direction side. Each of the detection coils 41 to 44 is positioned so as to be spaced apart from the via portions 41c to 44c of adjacent coils, and overlapping each other.

[0040] <Detection principle using a detection coil> Each of the detection coils 41-44 and the excitation coil 30 are magnetically coupled by a magnetic field generated from the excitation coil 30 toward the rotating body 10. As the rotating body 10, which has a sinusoidal outer edge, rotates, the area of ​​each of the four detection coils 41-44 facing the rotating body 10 changes in the Z direction. The facing area is the area of ​​the region where the sinusoidal portion of the rotating body 10 and each of the detection coils 41-44 overlap when viewed from the Z1 direction. Based on the change in the magnetic field accompanying this change in facing area, different alternating currents are induced in each of the detection coils 41-44.

[0041] In the rotation angle detection device 100, when the rotation of the rotating body 10 causes any of the detection coils 41 to 44 to face a peak on the sinusoidal outer edge of the rotating body 10, the eddy current generated in the opposing portion increases. The eddy current generated at this time is in a direction that cancels out the magnetic field applied from the excitation coil 30 and is generated from the rotating body 10 toward the portion of the detection coils 41 to 44 facing the peak. As a result, the magnetic field detected in the coil containing the portion of any of the detection coils 41 to 44 facing the peak becomes smaller, and therefore the induced current decreases. This results in the output of a sensor voltage corresponding to the change in induced current. This sensor voltage is a signal that detects the change in the magnetic field generated by the excitation coil 30.

[0042] As shown in Figure 5, the four detection coils 41, 42, 43, and 44 are arranged along the circumferential direction (R direction) with their coil centers C spaced apart by a predetermined arrangement pitch P. This arrangement pitch P is set based on the number of poles of the motor 101. In the motor 101, the electrical angle is determined according to the number of poles. The electrical angle is, for example, the size obtained by dividing the mechanical angle of the motor 101 (360 degrees) by half the number of poles. For example, if the motor 101 has 8 poles, one cycle of the electrical angle is equivalent to 90 degrees of the mechanical angle. In the rotation angle detection device 100, the four detection coils 41, 42, 43, and 44 are arranged in a line across this one cycle of the electrical angle. Therefore, the arrangement pitch P corresponds to one-quarter of one cycle of the electrical angle, which corresponds to 90 degrees of the electrical angle. For example, if the motor 101 has 8 poles, the arrangement pitch P will be one-quarter of the mechanical angle of 90 degrees. In the rotation angle detection device 100, the sine wave at the outer edge of the rotating body 10 is also formed such that one cycle corresponds to one cycle of the electrical angle.

[0043] Therefore, the detection coils 41 and 43, which are connected in series with each other, and the detection coils 42 and 44, are positioned at a distance of 0.5 periods of the sine wave at the outer edge of the rotating body 10. That is, the detection coils 41 and 43, and the detection coils 42 and 44 are positioned so that their electrical angles are 180 degrees apart in phase. In the rotation angle detection device 100, the detection coils 41 and 43 form a sine coil that outputs a detection result corresponding to a sine wave indicating the rotation of the rotating body 10, and the detection coils 42 and 44 form a cosine coil that outputs a detection result corresponding to a cosine wave indicating the rotation of the rotating body 10. Note that the configuration may also be reversed, with the sine and cosine coils reversed. Since the coil patterns of the detection coils 41 and 43, and the detection coils 42 and 44, which are connected in series with each other, are wound in opposite directions, positioning them at a distance of 0.5 periods of phase can reduce noise in the detected induced current and increase sensitivity. Furthermore, since the coil patterns of detection coils 41 and 43 are wound in opposite directions to each other, and to each other to each other, detection coils 42 and 44 produce signals with the offset of the detected induced current eliminated.

[0044] <Details of the placement of detection coils on the circuit board> As shown in Figure 5, the excitation coil 30 is arranged to extend in an arc shape along the circumferential direction (R direction) over a distance greater than one period of the sine wave at the outer edge of the rotating body 10. That is, the excitation coil 30 is arranged to surround at least one peak and at least one trough at the outer edge of the rotating body 10. For example, the excitation coil 30 has a circumferential size L on the substrate 70. 30 However, it is six times the size of the arrangement pitch P. Note that the size L in the circumferential direction of the detection coil 40 (each of the detection coils 41 to 44) 40 It is greater than the placement pitch P.

[0045] Here, as shown in Figure 6, the magnetic flux density due to the magnetic field applied to the rotating body 10 by the excitation coil 30 changes in a convex shape at both ends in the circumferential direction of the excitation coil 30. Taking this into consideration, in the rotation angle detection device 100 of the first embodiment, as described above, the circumferential size of the excitation coil 30 is set to 6 times, which is greater than 4 times the arrangement pitch P, so that the circumferential ends of the excitation coil 30 are positioned at a distance of one arrangement pitch P from the positions of both ends of the detection coils 41 to 44 in the circumferential direction. As a result, the detection coils 41 to 44 are arranged so as to avoid the circumferential ends of the excitation coil 30 where the change in magnetic flux density is large.

[0046] Furthermore, as shown in the enlarged view of Figure 6, the magnetic flux density due to the magnetic field applied to the rotating body 10 by the excitation coil 30 includes a periodic component (periodic pattern) that changes periodically in the circumferential direction (R direction). This periodic pattern has a predetermined superimposed magnetic field period T. As shown in Figure 7, the magnitude of this superimposed magnetic field period T is equal to the magnitude L of the excitation coil 30 in the circumferential direction. 30 It increases accordingly. The size L in the circumferential direction of the detection coils 41-44. 40 If the superimposed magnetic field period T is smaller than this superimposed magnetic field period, the detection accuracy of the detection coils 41-44 decreases due to the influence of the periodic component.

[0047] Therefore, in the first embodiment, the size L in the circumferential direction (R direction) of each of the multiple detection coils 41 to 44 is 40 The configuration is such that the magnitude L in the circumferential direction of each of the detection coils 41 to 44 is greater than the superimposed magnetic field period T. 40 This is greater than the arrangement pitch P. In other words, each of the multiple detection coils 41 to 44 has a magnitude of angle θ expressed by equation (3) in the circumferential direction (R direction) of the rotating body 10, when viewed from a direction perpendicular to the main surface of the substrate 70 (Z1 direction), where p is the number of poles of the motor 101 and k is a real number greater than 1.

number

[0048] As shown in Figure 8, the substrate 70 has a first layer L1, a second layer L2, a third layer L3, and a fourth layer L4 arranged in order from the main surface on the Z1 side opposite to the rotating body 10. Each of the plurality of detection coils 40 (detection coils 41 to 44) is formed as a coil pattern stacked on one of the four layers arranged in order from the main surface on the Z1 side opposite to the rotating body 10 on the substrate 70, namely the first layer L1, the second layer L2, the third layer L3, and the fourth layer L4. In the first embodiment, each of the detection coils 41 and 43 is formed as a coil pattern stacked on the first layer L1 and the third layer L3. Each of the detection coils 42 and 44 is formed as a coil pattern stacked on the second layer L2 and the fourth layer L4. For example, on the substrate 70, the coil patterns of the second layer L2 and the third layer L3 are formed on both sides of a plate-shaped core material made of glass epoxy resin using copper foil. Furthermore, a coil pattern for the first layer L1 is formed on the Z1 side, above the second layer L2, via a prepreg layer, and a coil pattern for the fourth layer L4 is formed on the Z2 side, below the third layer L3, via a prepreg layer, also via copper foil.

[0049] Specifically, portion 41a of detection coil 41 and portion 43a of detection coil 43 are located in the first layer L1, which has the largest distance D1 from the rotating body 10. Portion 41b of detection coil 41 and portion 43b of detection coil 43 are located in the third layer L3, which has the second smallest distance D3 from the rotating body 10. Portion 42a of detection coil 42 and portion 44a of detection coil 44 are located in the second layer L2, which has the second largest distance D2 from the rotating body 10. Portion 42b of detection coil 42 and portion 44b of detection coil 44 are located in the fourth layer L4, which has the smallest distance D4 from the rotating body 10.

[0050] In order to equalize the sensitivity of each of the detection coils 41 to 44, in the first embodiment, detection coils 41 and 43 have more turns than detection coils 42 and 44. Specifically, detection coils 41, which are located in the first layer L1 and third layer L3, which are relatively far from the rotating body 10, have more turns in their coil pattern than detection coils 44, which are located in the second layer L2 and fourth layer L4, which are relatively close to the rotating body 10. Similarly, detection coils 42, which are located in the first layer L1 and third layer L3, have more turns in their coil pattern than detection coils 42, which are located in the second layer L2 and fourth layer L4. Furthermore, since the detected magnetic field is larger on the outer side in the circumferential direction (R direction), detection coils 43, which are located on the inside, have more turns in their coil pattern than detection coils 41, which are located on the outside. Similarly, detection coils 42, which are located on the inside, have more turns in their coil pattern than detection coils 44, which are located on the outside. In the first embodiment, the sensitivity of each of the detection coils 41 to 44 is made equal by making the number of turns of each of the detection coils 41 to 44 different from each other. The portions 41a to 44a located in the first layer L1 and the second layer L2 on the Z1 direction side may have the same number of turns as the portions 41b to 44b located in the third layer L3 and the fourth layer L4 on the Z2 direction side, or they may have different numbers of turns.

[0051] Furthermore, the excitation coil 30 is formed on the substrate 70 by laminating it across two layers: a first layer L1 common to portions 41a and 43a, and a second layer L2 common to portions 42a and 44a. In addition, the conductors connecting each of the multiple detection coils 40, and the conductors connecting the multiple detection coils 40 to the sensor circuit section 50, are formed, for example, on either a third layer L3 or a fourth layer L4 that is different from the excitation coil 30.

[0052] <Sensor circuit section> As shown in Figure 3, the sensor circuit unit 50 is mounted on the substrate 70. The sensor circuit unit 50 includes a sensing IC (Integrated Circuit) for the inductive sensor. The sensor circuit unit 50 also includes electronic components such as resistors and capacitors mounted on the substrate 70. The induced current generated in the detection coil 40 is input to the sensor circuit unit 50 as the detection result. Based on the detection result (induced current) of the detection coil 40, the sensor circuit unit 50 is configured to output a rotation angle signal, which is a signal indicating the rotation angle of the rotating body 10, to the ECU 102 via a connector 71 provided on the substrate 70. The sensor circuit unit 50 functions as a converter that converts the detection signal from the detection unit 20, which is an analog signal, into the rotation angle signal, which is a digital signal. The sensor circuit unit 50 also outputs AC power (AC current) to the excitation coil 30 to generate a magnetic field.

[0053] In the first embodiment, a magnetic field is applied to the rotating body 10 by both the excitation coil 30 of the first detection unit 21 and the excitation coil 30 of the second detection unit 22. Based on the detection results from the detection coil 40 of the first detection unit 21 and the detection coil 40 of the second detection unit 22, rotation angle signals are separately output to the ECU 102 from the sensor circuit 50 of the first detection unit 21 and the sensor circuit 50 of the second detection unit 22. The ECU 102 controls the drive of the motor 101 based on either the rotation angle signal from the first detection unit 21 or the rotation angle signal from the second detection unit 22. The ECU 102 also determines abnormalities in the first detection unit 21 and the second detection unit 22, and if either the first detection unit 21 or the second detection unit 22 is determined to be abnormal, it controls the drive of the motor 101 based on the rotation angle signal from the other unit that is not determined to be abnormal. The above configuration is just one example of a redundant design, and reliability and availability can be enhanced using configurations different from the one described above.

[0054] (Effects of the first embodiment) In the first embodiment, the following effects can be obtained.

[0055] In the first embodiment, as described above, the detection coils 41 (first detection coil), 42 (second detection coil), 43 (third detection coil), and 44 (fourth detection coil) are arranged in a line along the circumferential direction (R direction) of the rotating body 10 on the substrate 70, and are formed such that at least one pair of adjacent coils have overlapping outer edges when viewed from a direction perpendicular to the main surface of the substrate 70 (Z1 direction). As a result, since at least one pair of adjacent coils have overlapping outer edges when viewed from a direction perpendicular to the main surface of the substrate 70, the area on the substrate 70 where the detection coils 40 are arranged can be increased by the amount of overlap of the outer edges of the coils. Therefore, even when miniaturizing the rotation angle detection device 100, it is possible to suppress a reduction in the number of turns of the multiple detection coils 40. As a result, miniaturization can be achieved while suppressing a decrease in the accuracy of rotation angle detection.

[0056] Furthermore, in the first embodiment, since each of the multiple detection coils 41 to 44 is formed by stacking them on the substrate 70, the size in the thickness direction can be reduced compared to stacking multiple substrates on which a single layer of conductor is formed. Therefore, an increase in the size of the device can be suppressed.

[0057] Furthermore, in the first embodiment, as described above, the detection unit 20 detects changes in the magnetic field of the rotating body 10 arranged on the motor 101. Each of the plurality of detection coils 40 (detection coils 41 to 44) has a magnitude of an angle θ expressed by equation (4), where p is the number of poles of the motor 101 and k is a real number greater than 1, in the circumferential direction (R direction) of the rotating body 10 when viewed from a direction perpendicular to the main surface of the substrate 70 (Z1 direction).

number

[0058] Furthermore, in the first embodiment, as described above, the substrate 70 has a first layer L1, a second layer L2, a third layer L3, and a fourth layer L4 arranged in order from the main surface opposite to the rotating body 10. Each of the detection coils 41 (first detection coil) and 43 (third detection coil) is formed by laminating the first layer L1 and the third layer L3. Each of the detection coils 42 (second detection coil) and 44 (fourth detection coil) is formed by laminating the second layer L2 and the fourth layer L4. The detection coils 41 and 43 have more turns than the detection coils 42 and 44. As a result, the detection coils 41 and 43 stacked in the first layer L1 and third layer L3 have more turns than the detection coils 42 and 44 stacked in the second layer L2 and fourth layer L4. Therefore, the number of turns of the detection coils 41 and 43, which are located at a relatively large distance from the rotating body 10, can be increased compared to the number of turns of the detection coils 42 and 44, which are located at a relatively small distance from the rotating body 10. Consequently, the difference between the detection sensitivity of the detection coils 41 and 43 and the detection sensitivity of the detection coils 42 and 44 can be reduced, thereby suppressing a decrease in the accuracy of rotation angle detection caused by the difference in detection sensitivity.

[0059] Furthermore, in the first embodiment, as described above, the detection unit 20 includes a first detection unit 21 and a second detection unit 22, each containing a plurality of detection coils 40 formed in a superimposed state. Each of the first detection unit 21 and the second detection unit 22 separately detects the change in the magnetic field due to the rotation of the rotating body 10. As a result, since the detection unit 20 includes a first detection unit 21 and a second detection unit 22 that separately detect the change in the magnetic field due to the rotation of the rotating body 10, the configuration for detecting the change in the magnetic field due to the rotation of the rotating body 10 can be made redundant. Therefore, even if an abnormality occurs in either the first detection unit 21 or the second detection unit 22, the change in the magnetic field due to the rotation of the rotating body 10 can be detected by the other, so the rotation angle can be continuously detected.

[0060] [Second Embodiment] A second embodiment will be described with reference to Figure 9. In this second embodiment, the layer on which the detection coils 241 to 244 are arranged on the substrate 70 is different from that of the first embodiment. In the figure, components the same as those in the first embodiment are denoted by the same reference numerals.

[0061] As shown in Figure 9, the rotation angle detection device 200 according to the second embodiment includes detection coils 241, 242, 243, and 244. Similar to the first embodiment, detection coils 241, 242, 243, and 244 constitute an inductive sensor that detects changes in the magnetic field caused by the rotation of a rotating body 10 to which a magnetic field is applied, by electromagnetic induction. Detection coils 241, 242, 243, and 244 are examples of the "first detection coil," "second detection coil," "third detection coil," and "fourth detection coil" in the claims, respectively.

[0062] Detection coils 241, 242, 243, and 244 are arranged in this order along the R1 direction on the substrate 70, similar to detection coils 41, 42, 43, and 44 of the first embodiment. Detection coils 241 and 243 are connected to each other with their coil patterns wound in opposite directions, similar to detection coils 41 and 43 of the first embodiment. Detection coils 242 and 244 are connected to each other with their coil patterns wound in opposite directions, similar to detection coils 42 and 44 of the first embodiment. Detection coils 241 to 244 are formed as a multilayer coil pattern with the outer edges of adjacent coils overlapping each other when viewed from a direction perpendicular to the main surface of the substrate 70 (Z1 direction), similar to the first embodiment.

[0063] Each of the multiple detection coils 241 to 244 is formed as a multilayer coil pattern stacked on the substrate 70 in one of four layers: the first layer L1, the second layer L2, the third layer L3, and the fourth layer L4, similar to the detection coils 41 to 44 of the first embodiment. Similar to the first embodiment, each of the detection coils 241 to 244 has two portions wound in different directions across two layers of the substrate 70, one on the Z1 side and the other on the Z2 side, and a via portion connecting the two portions. Specifically, the detection coil 241 has portion 241a, portion 241b, and via portion 241c. The detection coil 242 has portion 242a, portion 242b, and via portion 242c. The detection coil 243 has portion 243a, portion 243b, and via portion 243c. The detection coil 244 has a portion 244a, a portion 244b, and a via portion 244c. The winding directions of portions 241a to 244a are the same as those of portions 41a to 44a in the first embodiment. The winding directions of portions 241b to 244b are the same as those of portions 41b to 44b in the first embodiment.

[0064] In the second embodiment, each of the detection coils 241 and 243 is formed as a coil pattern stacked in the second layer L2 and the third layer L3. Each of the detection coils 242 and 244 is formed as a coil pattern stacked in the first layer L1 and the fourth layer L4. Specifically, portion 241a of the detection coil 241 and portion 243a of the detection coil 243 are located in the second layer L2, and portion 241b of the detection coil 241 and portion 243b of the detection coil 243 are located in the third layer L3. Portion 242a of the detection coil 242 and portion 244a of the detection coil 244 are located in the first layer L1, and portion 242b of the detection coil 242 and portion 244b of the detection coil 244 are located in the fourth layer L4.

[0065] In the second embodiment, the average of D2, the distance from the rotating body 10 of the second layer L2 where detection coils 241 and 243 are located, and D3, the distance from the rotating body 10 of the third layer L3, is equal to the average of D1, the distance from the rotating body 10 of the first layer L1 where detection coils 242 and 244 are located, and D4, the distance from the rotating body 10 of the fourth layer L4. Therefore, in order to equalize the sensitivity of each of the detection coils 241 to 244, in the second embodiment, detection coils 241 and 243 have the same number of turns as detection coils 242 and 244. Specifically, detection coils 241 and 244, which are located on the outside in the circumferential direction (R direction), have the same number of turns as each other, and detection coils 242 and 243, which are located on the inside in the circumferential direction, have the same number of turns as each other. In the second embodiment, as in the first embodiment, the detected magnetic field is larger on the outer side in the circumferential direction. Therefore, the detection coils 242 and 243, which are located on the inside, have more turns in their coil patterns compared to the detection coils 241 and 244, which are located on the outside.

[0066] The other configurations of the second embodiment are the same as those of the first embodiment described above, so their explanation will be omitted.

[0067] (Effects of the second embodiment) In the second embodiment, the following effects can be obtained.

[0068] In the second embodiment, the substrate 70 has a first layer L1, a second layer L2, a third layer L3, and a fourth layer L4 arranged in order from the main surface opposite to the rotating body 10. Each of the detection coils 241 (first detection coil) and 243 (third detection coil) is formed by laminating the second layer L2 and the third layer L3. Each of the detection coils 242 (second detection coil) and 244 (fourth detection coil) is formed by laminating the first layer L1 and the fourth layer L4. As a result, detection coils 242 and 244 are positioned in the first layer L1, which has the greatest distance from the rotating body 10, and the fourth layer L4, which has the smallest distance, respectively. Detection coils 241 and 243 are positioned in the second layer L2, which has the second largest distance from the rotating body 10, and the third layer L3, which has the second smallest distance. Therefore, the difference between the average distance from the rotating body 10 for detection coils 241 and 243 and the average distance from the rotating body 10 for detection coils 242 and 244 can be reduced. Consequently, the difference between the detection sensitivity of detection coils 241 and 243 and the detection sensitivity of detection coils 242 and 244 can be reduced, thereby suppressing a decrease in the accuracy of rotation angle detection due to differences in detection sensitivity.

[0069] Furthermore, the other effects of the second embodiment are the same as those of the first embodiment, so we will omit their explanation.

[0070] [Differentiation] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments, and further includes all modifications (modifications) within the meaning and scope equivalent to the claims.

[0071] For example, in the first and second embodiments described above, examples were shown in which via portions 41c to 44c and 241c to 244c, which connect the stacked coil patterns of the detection coils 41 to 44 and 241 to 244, are arranged at the coil center C, but the present invention is not limited thereto. In the present invention, each of the via sections 341c, 342c, 343c, and 344c that connect the stacked coil patterns (sections 41a and 41b, sections 42a and 42b, sections 43a and 43b, and sections 44a and 44b) in the rotation angle detection device 300 according to the modification shown in Figure 10, such as detection coil 341 (first detection coil), detection coil 342 (second detection coil), detection coil 343 (third detection coil), and detection coil 344 (fourth detection coil), may be positioned offset from the coil center C when viewed from the Z1 direction, which is perpendicular to the main surface of the substrate 70. Specifically, each of the via sections 341c, 342c, 343c, and 344c is positioned offset outward in the circumferential direction (R direction). Via sections 341c and 342c are positioned offset from the coil center C in the R2 direction. Via sections 343c and 344c are positioned offset from the coil center C of detection coil 343 and detection coil 344 in the R2 direction, respectively.

[0072] As described above, in the modified rotation angle detection device 300, at least one via portion 341c to 344c of the multiple detection coils 341 to 344 is positioned offset from the coil center C when viewed from a direction perpendicular to the main surface of the substrate 70 (Z direction). As a result, since the via portions 341c to 344c that connect the stacked coil patterns are positioned offset from the coil center C when viewed from a direction perpendicular to the main surface of the substrate 70, even if the size of each of the multiple detection coils 341 to 344 in the circumferential direction (R direction) is increased, physical interference between the outer edges of the detection coils 341 to 344 and the via portions 341c to 344c can be suppressed. Therefore, because the via portions 341c to 344c are offset from the coil center C, the size of the overlapping portion of each of the multiple detection coils 341 to 344 can be increased, and the number of turns of the multiple detection coils 341 to 344 can be increased. As a result, the decrease in the accuracy of rotation angle detection can be further suppressed. Alternatively, some of the vias of the four detection coils may be positioned offset from the coil center, while the remaining vias are positioned at the coil center.

[0073] Furthermore, while the first and second embodiments described above show examples in which each of the multiple detection coils 41-44, 241-244 (first detection coil to fourth detection coil) and the excitation coil 30 are formed as a coil pattern stacked on top of each other, the present invention is not limited thereto. In the present invention, each of the multiple detection coils may be formed as a coil pattern of only one layer on the substrate, or as a coil pattern stacked over three or more layers. Similarly, the excitation coil may be formed as a coil pattern of only one layer on the substrate, or as a coil pattern stacked over three or more layers.

[0074] Furthermore, while the first and second embodiments described above show examples in which the outer peripheral edges of each of the multiple detection coils 41-44 and 241-244 (first detection coil to fourth detection coil) overlap each other to form a multilayer coil pattern, the present invention is not limited thereto. In the present invention, the outer peripheral edges of at least one pair of adjacent coils among the multiple detection coils (first detection coil to fourth detection coil) may overlap each other to form a multilayer coil pattern. That is, at least one pair of adjacent first and second detection coils, second and third detection coils, and third and fourth detection coils may overlap each other, while other pairs may not overlap each other. For example, the second and third detection coils arranged on the inside in the circumferential direction may overlap each other, while the first and second detection coils and the third and fourth detection coils, arranged on the outside in the circumferential direction, may not overlap each other.

[0075] Furthermore, in the first and second embodiments described above, examples were shown in which each of the multiple detection coils 41-44 and 241-244 (first detection coil to fourth detection coil) has an angle in the circumferential direction (R direction) that is greater than one-quarter of one period of the electric angle of the motor 101 and greater than the superimposed magnetic field period T by the excitation coil 30, but the present invention is not limited to this. In the present invention, each of the first to fourth detection coils may have an angle in the circumferential direction that is less than or equal to one-quarter of one period of the electric angle of the motor. Also, each of the first to fourth detection coils may have an angle in the circumferential direction that is less than or equal to the periodic component (superimposed magnetic field period) of the magnetic field applied by the excitation coil 30.

[0076] Furthermore, while the first and second embodiments described above show examples in which multiple detection coils 41-44 and 241-244 (first detection coil to fourth detection coil) are spaced apart from each other in the circumferential direction by a predetermined arrangement pitch P, the present invention is not limited to this. In the present invention, the circumferential spacing distances between each of the first to fourth detection coils may be of different magnitudes. Each of the first to fourth detection coils may be arranged in a line over an angle different from one cycle of the motor's rotation angle.

[0077] Furthermore, in the first and second embodiments described above, the size L in the circumferential direction of the excitation coil 30 is also present. 30 Although an example has been shown where the arrangement pitch P is six times the predetermined arrangement pitch, the present invention is not limited to this. In the present invention, the circumferential size of the excitation coil may be less than or greater than six times the arrangement pitch.

[0078] Furthermore, in the first embodiment described above, an example was shown in which the detection coils 41 and 43, which are laminated in the first layer L1 and the third layer L3, have a greater number of turns than the detection coils 42 and 44, which are laminated in the second layer L2 and the fourth layer L4. However, the present invention is not limited to this. In the present invention, even when the first detection coil and the third detection coil are each formed in the first and third layers, and the second detection coil and the fourth detection coil are each formed in the second and fourth layers, the first detection coil and the third detection coil may have the same number of turns as the second and fourth detection coils.

[0079] Furthermore, in the first and second embodiments described above, examples were shown in which detection coils 41 and 241 (first detection coil) and adjacent detection coils 42 and 242 (second detection coil) are wound in the same direction, and detection coils 43 and 243 (third detection coil) and adjacent detection coils 44 and 244 (fourth detection coil) are wound in the same direction. However, the present invention is not limited to these examples. In the present invention, the first detection coil and the third detection coil may be wound in different directions. Also, the third detection coil and the fourth detection coil may be wound in different directions. For example, the first detection coil and the fourth detection coil may be wound in the same direction, and the second detection coil and the third detection coil may be wound in the same direction.

[0080] Furthermore, in the first embodiment described above, an example was shown in which detection coils 41 (first detection coil) and 43 (third detection coil) that form a sine coil are arranged in the first layer L1 and the third layer L3, and detection coils 42 (second detection coil) and 44 (fourth detection coil) that form a cosine coil are arranged in the second layer L2 and the fourth layer L4. However, the present invention is not limited to this. In the present invention, detection coils that form a sine coil may be formed in the second and fourth layers, and detection coils that form a cosine coil may be formed in the first and third layers. That is, the first detection coil and the third detection coil may be arranged in the second and fourth layers, and the second detection coil and the fourth detection coil may be arranged in the first and third layers. Similarly, in the second embodiment described above, an example was shown in which detection coils 241 (first detection coil) and 243 (third detection coil) forming a sine coil are arranged in the second layer L2 and the third layer L3, and detection coils 242 (second detection coil) and 244 (fourth detection coil) forming a cosine coil are arranged in the first layer L1 and the fourth layer L4. However, in the present invention, the first detection coil and the third detection coil may be arranged in the first and fourth layers, and the second detection coil and the fourth detection coil may be arranged in the second and third layers. Furthermore, multiple detection coils may be formed by stacking them in any of five or more layers on the substrate. That is, the first detection coil and the third detection coil may be arranged in different layers, and the second detection coil and the fourth detection coil may be arranged in different layers.

[0081] Furthermore, while the first and second embodiments described above show an example of making the rotation angle detection configuration redundant by arranging two detection units 20, a first detection unit 21 and a second detection unit 22, on a common substrate 70, the present invention is not limited thereto. In the present invention, in order to make the rotation angle detection configuration redundant, three or more detection units may be formed on a common substrate. Alternatively, the first detection unit and the second detection unit may be arranged on separate substrates. Alternatively, the rotation angle detection configuration may not be made redundant and may include only one detection unit.

[0082] Furthermore, while the first and second embodiments described above show examples in which the rotation angle detection devices 100 and 200 are configured to detect the rotation angle of a motor 101 used in a drive source for driving, a power window, a sliding door, and a shift-by-wire system, the present invention is not limited thereto. In the present invention, the rotation angle detection device may be configured to detect the rotation angle of a rotating body such as a crankshaft and camshaft of a vehicle. Alternatively, the rotation angle detection device may be configured to detect the rotation angle of a motor used in a moving body other than a vehicle or in a device other than a moving body. [Explanation of Symbols]

[0083] 10...Rotating body, 20...Detection unit, 30...Excitation coil, 41 (241, 341)...Detection coil (1st detection coil), 42 (242, 342)...Detection coil (2nd detection coil), 43 (243, 343)...Detection coil (3rd detection coil), 44 (244, 344)...Detection coil (4th detection coil), 70...Circuit board, 100 (200, 300)...Rotation angle detection device, 101...Motor

Claims

1. An excitation coil that applies a magnetic field to a rotating body by passing an alternating current through it, A detection unit comprising a plurality of detection coils, which constitutes an inductive sensor that detects changes in the magnetic field caused by the rotation of the rotating body to which a magnetic field is applied by the excitation coils, by electromagnetic induction, The detection unit comprises a substrate on which the plurality of detection coils are formed, The plurality of detection coils include a first detection coil and a third detection coil connected to each other, and a second detection coil and a fourth detection coil connected to each other. A rotation angle detection device wherein the first detection coil, the second detection coil, the third detection coil, and the fourth detection coil are arranged in a line along the circumferential direction of the rotating body on the substrate, and when viewed from a direction perpendicular to the main surface of the substrate, the outer peripheral edges of at least one pair of adjacent coils are formed to overlap each other.

2. The detection unit detects changes in the magnetic field of the rotating body arranged in the motor, The rotation angle detection device according to claim 1, wherein each of the plurality of detection coils has a magnitude equal to an angle θ expressed by formula (1), where p is the number of poles of the motor and k is a real number greater than 1, in the circumferential direction of the rotating body when viewed from a direction perpendicular to the main surface of the substrate. [Math 1]

3. The substrate has a first layer, a second layer, a third layer, and a fourth layer arranged in order from the main surface opposite to the rotating body. Each of the first detection coil and the third detection coil is formed by stacking the first and third layers, Each of the second detection coil and the fourth detection coil is formed by stacking the second and fourth layers, The rotation angle detection device according to claim 1 or 2, wherein the first detection coil and the third detection coil have more turns than the second detection coil and the fourth detection coil.

4. The substrate has a first layer, a second layer, a third layer, and a fourth layer arranged in order from the main surface opposite to the rotating body. Each of the first detection coil and the third detection coil is formed by stacking the second and third layers, The rotation angle detection device according to claim 1 or 2, wherein each of the second detection coil and the fourth detection coil is formed by stacking in the first layer and the fourth layer.

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