JP2015094615A - Rotation detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a rotation detection device to be applied to even a rotating body pierced by a revolving shaft and allow an absolute rotation angle of a rotating body to be detected with high resolution.SOLUTION: A rotation detection device includes rotary magnets 21 and 22 attached to a revolving shaft 10. The rotary magnet 21 has a first magnetic pattern comprising magnetic poles at equal intervals, and the rotary magnet 22 has a second magnetic pattern including a first block 22a comprising magnetic poles at equal intervals and a second block 22b having a magnetization angle different from that of the first block 22a and comprising magnetic poles at equal intervals The sum total of the numbers of magnetic poles of the first and second blocks 22a and 22b is equal to the number of magnetic poles of the first magnetic pattern. A first magnetic sensor 30 is made to face the first magnetic pattern, and second and third magnetic sensors 40 and 50 are shifted by 90° and are made to face the second magnetic pattern. Each of the first to third magnetic sensors 30, 40, and 50 outputs two detection signals different in phase by 90°.

Description

  The present invention relates to a rotation detection device that detects an absolute rotation angle of a rotating body.

  2. Description of the Related Art Conventionally, it has been known that a permanent magnet is provided on a rotating body, a magnetic sensor is disposed facing a magnetic pattern of the permanent magnet, and a rotation angle of the rotating body is detected using a magnetic sensor output. For example, the rotation detection device disclosed in Patent Document 1 below includes a SV-GMR type magnetic sensor that outputs a pair of sine wave signals whose phases are shifted by 90 degrees, and a rotation axis of a rotating body. An orthogonal rotating surface is arranged opposite to the first magnetic pattern magnetized in two poles (N pole and S pole) by 180 degrees around the rotation axis, and the phase is 90 degrees out of the magnetoresistive effect element. A second magnetic sensor that outputs a sine wave signal is disposed so that the side surface of the rotating body is opposed to a second magnetic pattern that is magnetized in multiple poles by a small predetermined angle around the circumferential direction. Then, the output of the first magnetic sensor is subjected to arctangent calculation processing to obtain a sawtooth wave signal that changes in one cycle per rotation of the rotating body, and the output of the second magnetic sensor is rotated by arctangent calculation processing. A sawtooth wave signal that changes in multiple cycles per rotation of the body is obtained, and the absolute rotation angle of the rotor is calculated by interpolation processing using the two sawtooth wave signals.

The rotation detection device disclosed in the following Patent Document 2 includes a first magnetic sensor that includes a Hall element and outputs a pair of sine wave signals whose phases are shifted by 90 degrees. A second magnetic sensor, which is a Hall element and outputs a sine wave signal that is 90 degrees out of phase, is arranged around the side of the rotating body. The first magnetic pattern is arranged so as to be opposed to the second magnetic pattern magnetized in multiple poles by changing the number of poles by a small predetermined angle around the direction. The outputs of the first and second magnetic sensors are each subjected to arc tangent calculation processing to obtain two sawtooth wave signals that change in different numbers of multiple periods per rotation of the rotating body, thereby obtaining two sawtooth waves. The absolute rotation angle of the rotating body is calculated by calculating the signal difference signal. That is, assuming that the signal periods from the first and second magnetic sensors are a period and b period, respectively, the absolute rotation angle φ of the rotating body is calculated by the vernier calculation shown in the following formula 1.

  In this case, since the first and second magnetic patterns are provided on the circumference, the number of poles of the first and second magnetic patterns is always an even number, that is, the values a and b are even numbers, The minimum difference is ± 2. The first and second magnetic sensors of this rotation detection device are composed of Hall elements, and the first and second magnetic sensors output a signal of one cycle with a pair of two poles (N pole and S pole). Therefore, the minimum value ± 2 is halved to a minimum value of ± 1, and the above calculation of 1 (vernier calculation) is established.

JP 2012-215415 A JP 2008-267867 A

  However, in the conventional rotation detection device disclosed in Patent Document 1, the first magnetic sensor is disposed on an extension of the central axis of the rotation body, and the rotation body device has a structure that penetrates the rotation shaft. There is a problem that cannot be applied. Even if it can be applied, it is necessary to move the first magnetic sensor away from the rotation axis, so that an error in the rotation angle becomes large. In the conventional rotation detection device shown in Patent Document 2, the first and second magnetic patterns form a pair of two poles (N pole and S pole) and output a signal of one cycle. The resolution is lower than that of the rotation detection device disclosed in Patent Document 1. And in order to achieve the resolution equivalent to the resolution by the rotation detection apparatus of the said patent document 1, the pole number of the 1st and 2nd magnetic pattern is made into twice the pole number of the 2nd magnetic pattern of the said patent document 1. There is a problem that needs to be done.

  The present invention has been made to cope with the above-described problem, and the object thereof can be applied to a rotating body having a rotating shaft penetrated, and the absolute rotation angle of the rotating body can be detected with high resolution, that is, high detection accuracy. An object of the present invention is to provide a rotation detection device. In addition, in the description of each constituent element of the present invention below, in order to facilitate understanding of the present invention, reference numerals of corresponding portions of the embodiment are described in parentheses, but each constituent element of the present invention is The present invention should not be construed as being limited to the configurations of the corresponding portions indicated by the reference numerals of the embodiments.

  In order to achieve the above object, the structural feature of the present invention includes a first magnetic pattern formed in a circular shape or an annular shape, in which N poles and S poles are alternately arranged along the circumferential direction, A first rotating magnet (21, 21A) that is attached to the rotating body (10, 11) and rotates in accordance with the rotation of the rotating body, and is formed in a circular shape or an annular shape along the circumferential direction with an N pole and an S pole Second rotating magnets (22, 22A) having second magnetic patterns alternately arranged and rotating around a rotation axis common to the first rotating magnets according to the rotation of the rotating bodies. , Arranged opposite to the first magnetic pattern, detects a change in the magnetic field due to the first magnetic pattern, and outputs two detection signals (A0, B0) having different phases in one cycle per pole of the first magnetic pattern Facing the first magnetic sensor (30, 30A) and the second magnetic pattern The second magnetic sensors (40, 40) that detect the change of the magnetic field due to the second magnetic pattern and output two detection signals (A1, B1) having different phases in one cycle per pole of the second magnetic pattern. 40A), opposed to the second magnetic pattern, and disposed 90 degrees away from the second magnetic sensor in the circumferential direction of the second rotating magnet, and detects a change in the magnetic field due to the second magnetic pattern to detect the second magnetic pattern. A rotation detecting device including a third magnetic sensor (50, 50A) that outputs two detection signals (A2, B2) having different phases in one cycle per one pole of the pattern, wherein the first magnetic pattern The N and S poles are alternately magnetized evenly at one magnetization angle and have an even number of poles, and the second magnetic pattern is even at a second magnetization angle smaller than the first magnetization angle. The first block magnetized alternately on the N and S poles (22a) and a second block (22b) which is alternately magnetized alternately with N and S poles at a third magnetization angle larger than the first magnetization angle. The sum of the number of poles of the two blocks is set to be equal to the number of poles of the first magnetic pattern, the first to third magnetization angles are λ0, λ1, and λ2, respectively. When the total number of poles of the first and second blocks of the magnetic pattern is n, and the difference between the number of poles of the first block and the second block is 2 · a, (n + 2a−2) / (n + 2 · a) ≦ λ1 / λ0 <1 and 1 <λ2 / λ0 ≦ (n−2a + 2) / (n−2a) are satisfied.

  In this case, for example, the two detection signals output from the first magnetic sensor are sinusoidal signals whose phases differ by 90 degrees or almost 90 degrees, and the two detection signals output by the second magnetic sensor have a phase of 90. The two detection signals output by the third magnetic sensor are sinusoidal signals whose phases differ by 90 degrees or almost 90 degrees.

  In the present invention configured as described above, if the detection signals from the first to third magnetic sensors are input to the signal processing circuit and processed, the absolute rotation angle of the rotating body is calculated as will be described later. Can do. In this case, the first magnetic sensor detects a change in the magnetic field due to the first magnetic pattern, outputs two detection signals having different phases in one cycle per pole of the first magnetic pattern, and outputs the second and third magnetic signals. The sensor detects a change in the magnetic field due to the second magnetic pattern, and outputs two detection signals having different phases in one cycle per pole of the second magnetic pattern. Therefore, if the number of poles of the magnetic pattern is the same as that of the rotation detection device disclosed in Patent Document 2, the absolute rotation angle can be detected with twice the resolution, and the absolute rotation angle of the rotating body can be detected with high accuracy. Can be detected. In the present invention having the above-described configuration, the first to third magnetic sensors are not provided on the extension line of the central axis of the rotating body, and therefore can be applied to a rotating body having a structure that allows the rotating shaft to pass therethrough. The rotation detection device having the above-described configuration can of course be applied to a rotating body having a structure that allows the rotation shaft to pass therethrough, and the present invention is not intended to be applied only to a rotating body having a structure that does not allow the rotation shaft to pass through. Absent.

  Another feature of the present invention is that two detection signals output by the first magnetic sensor, two detection signals output by the second magnetic sensor, and two detection signals output by the third magnetic sensor are further provided. A signal processing circuit (80) for inputting a signal and calculating a rotation angle of the rotating body using the input detection signal is provided.

  In this case, for example, the signal processing circuit calculates the first arc tangent value (θ0) by performing an arc tangent operation on the two detection signals output by the first magnetic sensor, and outputs the two arc output signals output by the second magnetic sensor. The detection signal is subjected to arc tangent calculation to calculate the second arc tangent value (θ1), and the two detection signals output by the third magnetic sensor are subjected to arc tangent calculation to calculate the third arc tangent value (θ2). The arc tangent calculation process (S14), the phase difference between the first arc tangent value and the second arc tangent value is calculated as the first phase difference value (φ1), and the first arc tangent value and the second arc tangent value are calculated. A phase difference calculation process (S16) for calculating the phase difference of the rotating body as a second phase difference value (φ2), and a rotation angle derivation for deriving the rotation angle of the rotating body using the first phase difference value and the second phase difference value. Arithmetic processing (S18 to S28) is executed. The process of calculating the phase difference between the first arc tangent value and the second arc tangent value as the first phase difference value, and the phase difference between the first arc tangent value and the second arc tangent value is the second phase difference value. Are calculated as vernier operations.

  In the present invention configured as described above, by using each of the two detection signals of the first to third magnetic sensors, both increase linearly with respect to one rotation of the rotating body and then turn back and linearly. It is possible to obtain two phase difference values (corresponding to the first and second phase difference values) in one cycle that change so as to decrease. Then, the other phase difference values at the rotation angle at which one phase difference value becomes the minimum value and the maximum value coincide with each other. Therefore, if the value of the two other phase difference values that coincide is X, one phase difference value increases from the minimum value to the maximum value in the angle range of the other phase difference value that is equal to or greater than the value X (or In the angle range of the other phase difference value that is less than or equal to the value X, one phase difference decreases from the maximum value to the minimum value (or increases from the minimum value to the maximum value) ( (See FIGS. 8, 14, and 15). Therefore, in one phase difference value, if the absolute value of the difference between the phase difference value after the maximum value and the maximum value is added to the maximum value, one phase difference value changes to the maximum value. By using the added value after the maximum value, the absolute rotation angle for one rotation of the rotating body can be calculated and output.

  Another feature of the present invention is that the signal processing circuit further executes the calculated rotation angle interpolation processing (S30) using the calculated first arc tangent value. is there. According to this, the absolute rotation angle of the rotating body can be made high resolution.

  Another feature of the present invention is that the difference between the number of poles of the first block and the number of poles of the second block is “2”. According to this, with respect to the rotation angle of 360 degrees of the rotating body, the angle range of the first and second blocks can be 180 degrees, which is half of 360 degrees, or close to 180 degrees. Therefore, the angle error (that is, the difference between the electrical angle and the mechanical angle) with respect to the rotation angle of 360 degrees of the rotating body can be reduced, and the accuracy of the absolute rotation angle can be improved. Furthermore, as the angle range of the first and second blocks approaches 180 degrees, the first and second phase difference values described above can be changed over a wide range, and the resolution of the absolute rotation angle can be maintained with high accuracy. Can also be increased.

  Another feature of the present invention is that the first to third magnetic sensors include a first bridge circuit (31, 41, 31) in which a plurality of magnetoresistive elements (31a to 31d) extending in the same plane are bridge-connected. 51) and a second bridge circuit (32, 42, 52) in which a plurality of magnetoresistive elements (32a to 32d) extended in the same plane are bridge-connected, and the first bridge of the first magnetic sensor The magnetosensitive elements of the plurality of magnetoresistive elements constituting the circuit and the second bridge circuit are arranged in a plane in which the lines of magnetic force due to the first magnetic pattern travel, and the first bridge circuit and the second bridge circuit of the second magnetic sensor are respectively provided. The magnetosensitive surfaces of the plurality of magnetoresistive elements are arranged in a plane along which the magnetic field lines of the second magnetic pattern travel, and the first bridge circuit and the second bridge circuit of the third magnetic sensor are configured, respectively. Certain sensitive surface of the plurality of magnetoresistance elements that have to be disposed in a plane which magnetic lines of force proceeds according to the second magnetic pattern.

  In this case, for example, the extending direction of the plurality of magnetoresistive elements constituting the first bridge circuit is different from the extending direction of the plurality of magnetoresistive elements constituting the second bridge circuit by 45 degrees, respectively. To do.

  According to this, each of the first to third magnetic sensors detects a change in the magnetic field by the first and second bridge circuits each including a plurality of magnetoresistive elements and outputs two detection signals. The detection accuracy is improved, and the absolute rotation angle of the detected rotating body becomes high accuracy.

  Another feature of the present invention is that in each of the first to third magnetic sensors, a plurality of magnetoresistive elements constituting the first bridge circuit and a plurality of magnetoresistive elements constituting the second bridge circuit are provided. Are arranged so that the center of gravity (C1) of the plurality of magnetoresistive elements constituting the first bridge circuit passes through the center of gravity (C2) of the plurality of magnetoresistive elements constituting the second bridge circuit. It exists in being located on the straight line orthogonal to the plane where the several magnetoresistive element which comprises a 2 bridge circuit is arrange | positioned. According to this, since the first and second bridge circuits detect a change in the magnetic field that changes with the same magnitude, each two detection accuracy output from the first to third magnetic sensors is further improved, The absolute rotation angle of the detected rotating body becomes even more accurate.

  Another feature of the present invention is that in each of the first to third magnetic sensors, the plurality of magnetoresistive elements constituting the first bridge circuit and the plurality of magnetoresistive elements constituting the second bridge circuit are the same. The center of gravity (C1) of the plurality of magnetoresistive elements constituting the first bridge circuit and the center of gravity (C2) of the plurality of magnetoresistive elements constituting the second bridge circuit are made to coincide with each other. It is in that.

  Also in this manner, as in the case described above, the first and second bridge circuits detect changes in the magnetic field that change with the same magnitude, so that each of the two detection accuracies output from the first to third magnetic sensors has high detection accuracy. Further improved, the absolute rotation angle of the detected rotating body becomes even more accurate. In addition, since the plurality of magnetoresistive elements constituting the first bridge circuit and the plurality of magnetoresistive elements constituting the second bridge circuit are arranged in the same plane, the manufacture of the first to third magnetic sensors is performed. In the process, the first and second bridges can be manufactured simultaneously in one manufacturing process, and the first to third magnetic sensors can be manufactured easily and inexpensively.

  Another feature of the present invention is that the first rotating magnet (21) and the second rotating magnet (22) are arranged in two rows in the rotation axis direction and have the same outer diameter or inner diameter. A first rotating magnet and a second rotating magnet that are outside the outer peripheral surfaces of the first and second rotating magnets having the same diameter or inside the inner peripheral surfaces of the first and second rotating magnets having the same inner diameter. A flat substrate extending in the circumferential direction is disposed at the boundary position of the substrate, the first magnetic sensor (30) is fixed to one surface of the substrate so as to face the first magnetic pattern, and the second and The third magnetic sensor is fixed to the other surface of the substrate so as to face the second magnetic pattern. According to this, since the first to third magnetic sensors can be mounted on one substrate, the structure of the rotation detection device is simplified.

  Another feature of the present invention is that one of the first rotating magnet (21A) and the second rotating magnet (21B) has a circular or annular shape, and the first rotating magnet and the second rotating magnet. The other rotary magnet is formed in an annular shape having an inner diameter larger than the outer diameter of one of the rotary magnets, and the first and second rotary magnets are radially aligned at the same position in the rotational axis direction. The rotating shafts are arranged in the same manner in two rows, and extend in the circumferential direction so as to face the one surface at a position away from one surface in the rotating shaft direction of the first and second rotating magnets. The provided flat substrate is disposed, and the first to third magnetic sensors (30A, 40A, 50A) are fixed to the surfaces of the substrate facing the first and second rotating magnets, and the first magnetic sensor is fixed to the first magnetic sensor. 1 and the second and third magnetic sensors are opposed to the second magnetic pattern. In that so as to face the over down. This also makes it possible to mount the first to third magnetic sensors on one substrate, thereby simplifying the structure of the rotation detection device.

  Another feature of the present invention is that the first magnetic sensor is disposed between the second magnetic sensor and the third magnetic sensor in the circumferential direction of the first and second rotating magnets. According to this, the first to third magnetic sensors can be mounted on the substrate only by slightly increasing the circumferential extension angle of the substrate from 90 degrees, so that the substrate can be reduced in size.

(A) is a schematic plan view of a rotation detection device, (b) is a schematic side view of the rotation detection device, and (c) is a schematic perspective view of the rotation detection device. (A) is explanatory drawing for demonstrating the magnetization state of a rotating magnet, (b) is a plane | planar expansion | deployment figure of a 1st magnetic pattern, (c) is a plane | planar expansion | deployment figure of a 2nd magnetic pattern. (A) is a layout diagram of magnetoresistive elements for explaining the first full bridge circuit of the magnetic sensor, and (b) is a layout diagram of magnetoresistive elements for explaining the second full bridge circuit of the magnetic sensor. (C) is a schematic diagram for explaining the magnetoresistive elements constituting the bridge circuit, (d) is a schematic diagram for explaining the arrangement of the full bridge circuit and the rotating magnet, and (e) is It is a signal waveform diagram output from the 1st and 2nd full bridge circuit. It is a block diagram of the electric circuit of a rotation detection apparatus. It is a flowchart showing the program performed by the signal processing circuit of FIG. It is a wave form diagram of a detection signal outputted from a magnetic sensor. It is a wave form diagram which shows the change of the arctangent angle calculated | required from the detection signal shown in FIG. It is a graph which shows the phase difference between the arctangent angles of FIG. It is a graph for demonstrating the process which calculates an increase flag from the change of the phase difference of FIG. It is a graph which demonstrates calculation of an absolute rotation angle, and shows a 1st simulation result. It is explanatory drawing for demonstrating an interpolation calculation process. It is explanatory drawing for demonstrating theoretical calculation of an absolute rotation angle. It is explanatory drawing for demonstrating the range of the magnetization angle which enables calculation of an absolute rotation angle. It is a graph which shows a 2nd simulation result. It is a graph which shows a 3rd simulation result. It is a graph which shows a 4th simulation result. It is a graph which shows a 5th simulation result. It is a graph which shows a 6th simulation result. It is a graph which shows the change of the absolute rotation angle which is a 7th thru | or 9th simulation result. It is an arrangement view of magnetoresistive elements for explaining another full bridge circuit. It is an arrangement view of magnetoresistive elements for explaining a half bridge circuit. It is the schematic which shows the positional relationship of the bridge circuit and rotary magnet for demonstrating the other example of arrangement | positioning of a bridge circuit. (A) is a schematic top view of another rotation detection device, (b) is a schematic side view of another rotation detection device, and (c) is a schematic bottom view of another rotation detection device. (A) and (b) are the top views and bottom views of a rotation detector which show other examples of arrangement of a magnetic sensor. It is a bottom view of the rotation detection device showing another arrangement example of the magnetic sensor.

a. Embodiment Hereinafter, a configuration of a rotation detection device according to an embodiment of the present invention will be described with reference to the drawings. 1A to 1C schematically show a rotation detection device, and particularly show the positional relationship between a rotary magnet and a magnetic sensor. FIG. 1A is a plan view, FIG. 1B is a side view, and FIG. 1C is a perspective view. In FIG. 1C, the substrate 60 is omitted. The rotation detection device includes rotating magnets 21 and 22 and first to third magnetic sensors 30, 40, and 50 that detect the rotation of the rotating magnets 21 and 22.

  The rotating magnets 21 and 22 are formed in an annular shape, and are fixed to the outer peripheral surface of the rotating shaft 10 on the inner peripheral surface thereof. The rotating magnets 21 and 22 are arranged in two rows in the axial direction of the rotating shaft 10 and have first and second magnetic patterns magnetized along the circumferential direction, respectively. In the following description, the axial direction of the rotary shaft 10 is the vertical direction. The first magnetic pattern is a magnetized pattern in which N and S poles are alternately magnetized at equal intervals over the entire circumference (360 degrees) in the circumferential direction. The second magnetic pattern is a first block 22a that is a magnetized pattern in which N poles and S poles are alternately magnetized at equal intervals in the circumferential direction at 180 degrees, and the remaining 180 degrees at equal intervals. And a second block 22b which is a magnetization pattern in which N poles and S poles are alternately magnetized. In the present embodiment, the total number n of N poles and S poles in the first magnetic pattern is “16”. The total number n1 of N poles and S poles in the first block is [9], and the total number n2 of N poles and S poles in the second block 22b is “7”. Accordingly, the circumferential magnetization width of the first block 22a is different from the circumferential magnetization width of the second block 22b.

  In the present embodiment, the number of poles n, n1, and n2 in the first and second blocks 22a and 22b of the first magnetic pattern and the second magnetic pattern are “16”, “9”, and “7”, respectively. As will be described in detail later, the following relationship may suffice between the number of poles n of the first magnetic pattern and the number of poles n1 and n2 of the first and second blocks 22a and 22b of the second magnetic pattern. That is, in the first magnetic pattern, adjacent poles are different poles (N pole and S pole), so the number of poles n is an even number, and is equal to the added value n1 + n2 of the number of poles n1 and the number of poles n2. The magnetic poles (N and S poles) of one end of the first block adjacent to each other and one end of the first block 22b are different, and the magnetic poles of the other end of the first block adjacent to each other and the other end of the second block 22b. Since (N and S poles) are different, the number of poles n1 and n2 are both even or odd, and the absolute value | n1−n2 | of the difference between the number of poles n1 and n2 includes “0”. Is a multiple of. Furthermore, in this embodiment, for the sake of simplicity, the angles of the first and second blocks 22a and 22b of the second magnetic pattern are both set to 180 degrees, but this will also be described in detail later. If the sum of the angles of the first and second blocks 22a and 22b is 360 degrees, the angle of the first and second blocks 22a and 22b may not be 180 degrees.

  This magnetization pattern will be described with reference to FIG. As shown in FIG. 2A, the magnetization pattern is magnetized with a predetermined magnetization angle λ in the radial direction from the center of the rotating magnets 21 and 22. In the first magnetic pattern, the magnetization angle λ0 (360/16 = 22.5 degrees in the present embodiment) is shown in the plan development view of FIG. 2B in which the outer peripheral surface of the magnetization pattern extends in the lateral direction. ) Is evenly magnetized over the entire circumference. In the second magnetic pattern, as shown in the plan development view of FIG. 2C similar to FIG. 2B, the magnetization angle λ1 in the first block 22a (180/9 = 20 degrees in the present embodiment). The second block 22b is equally magnetized at a magnetization angle λ2 (180/7 = 25.71 degrees in this embodiment). The magnetization angles λ0, λ1, and λ2 have a relationship of λ1 <λ0 <λ2.

  The rotating magnets 21 and 22 may magnetize the first magnetic pattern and the second magnetic pattern on an integral magnetic body, or two magnets that magnetize the first magnetic pattern and the second magnetic pattern, respectively. The body may be laminated. In the above example, the annular rotary magnets 21 and 22 are fixed on the outer peripheral surface of the rotary shaft 10, but the rotary magnets 21 and 22 are configured in a circular shape, and the upper surfaces of the rotary magnets 21 and 22 and Alternatively, the rotary shaft 10 may be fixed to the lower surface.

  The first magnetic sensor 30 is fixed to the upper surface of the substrate 60, and is disposed radially outward at the intermediate position in the vertical direction of the rotating magnet 21. The second and third magnetic sensors 40, 50 are fixed to the lower surface of the substrate 60 and are arranged radially outside at the intermediate position in the vertical direction of the rotary magnet 22. The radial distances from the centers of the rotary magnets 21, 22 of the first to third magnetic sensors 30, 40, 50 are all the same. The circumferential positions of the second and third magnetic sensors 40 and 50 are different from each other by 90 degrees around the center of the rotating magnet 22. The circumferential position of the first magnetic sensor 30 may be any position around the center of the rotating magnet 21, but the second and third magnetic sensors 40, 50 in the circumferential direction in order to reduce the area of the substrate 60. Between. The substrate 60 is formed in a flat plate shape, extends in the circumferential direction by an angle slightly larger than 90 degrees at an outer position of the rotary magnets 21 and 22, and is fixed to a member (not shown). The electric circuit to be arranged is arranged.

  The first to third magnetic sensors 30, 40, and 50 each output a pair of sine wave signals (sine wave signal and cosine wave signal) having a phase difference of 90 degrees with one magnetic pole as one cycle (see FIG. 6 (a) to (c)). Specific configurations of the first to third magnetic sensors 30, 40, and 50 will be described with reference to FIG. The first magnetic sensor 30 includes first and second full bridge circuits 31 and 32.

  As shown in FIG. 3A, the first full bridge circuit 31 includes four anisotropic magnetoresistive elements 31a, 31b, 31c, and 31d formed of ferromagnetic layers. The anisotropic magnetoresistive elements 31a and 31c are outer peripheral surfaces that are close to the magnetic sensor 30 of the rotating magnet 21 in a plane parallel to the rotating surface of the rotating magnet 21, as indicated by thick lines in FIG. It extends in a direction inclined 45 degrees with respect to the tangential direction of the position. The anisotropic magnetoresistive elements 31b and 31d are orthogonal to the anisotropic magnetoresistive elements 31a and 31c in a plane parallel to the rotating surface of the rotating magnet 21, as indicated by a thick line in FIG. It is extended in the direction to do. The extending directions of the anisotropic magnetoresistive elements 31a and 31c and the anisotropic magnetoresistive elements 31b and 31d do not necessarily have to be the above-described directions, but the anisotropic magnetoresistive elements 31a and 31c are extended. The installation direction and the extending direction of the anisotropic magnetoresistive elements 31b and 31d form an angle of 90 degrees.

  These anisotropic magnetoresistive elements 31a, 31b, 31c, and 31d are similarly configured except for the extending direction. Specifically, the anisotropic magnetoresistive effect elements 31a, 31b, 31c, and 31d extend the thin and long ferromagnetic layer film as shown in FIG. The extending direction of the anisotropic magnetoresistive effect elements 31a, 31b, 31c, and 31d is the extending direction of the ferromagnetic layer film. In the present specification, the extended surfaces of the ferromagnetic layers of the four anisotropic magnetoresistive elements 31a, 31b, 31c, 31d are referred to as magnetosensitive surfaces of the magnetic sensor (anisotropic magnetoresistive element).

  In the anisotropic magnetoresistive effect elements 31a, 31b, 31c, and 31d configured as described above, the anisotropic magnetoresistive effect elements 31a and 31b are connected in series, and a voltage Vcc is applied to both ends thereof. Thus, the voltage at these connection points is taken out as a voltage signal V1a. Further, the anisotropic magnetoresistive elements 31d and 31c are connected in series, and the voltage Vcc is applied to both ends thereof, and the voltage at the connection point is taken out as the voltage signal V2a. These voltage signals V1a and V2a are subtracted by a differential amplifier 33 in the electric circuit described later and output as a detection signal A0 (= V1a−V2a) (see FIG. 4).

  The detection signal A0 will be described with reference to FIG. 3D in which the direction of the magnetic field is indicated by an arrow. The center-of-gravity position C1 in the extending surface of the anisotropic magnetoresistive effect elements 31a, 31b, 31c, 31d of the first full bridge circuit 31 is located at regular intervals from the position a corresponding to one pole of the rotating magnet 21 to the position e. , B, c, d, e. In this case, the positions a, b, c, d, and e are distances P / 4, P / 2, 3P / 4, 4P / 4 from the position a when one pole of the magnetic pattern is 1 pitch (P). Represents a position that is only a distance away. At the position b, since the resistance values of the anisotropic magnetoresistive elements 31a and 31c are minimum and the resistance values of the anisotropic magnetoresistive elements 31b and 31d are maximum, the detection signal A0 is maximum (positive). At the position d, since the resistance values of the anisotropic magnetoresistive elements 31b and 31d are minimum and the resistance values of the anisotropic magnetoresistive elements 31a and 31c are maximum, the detection signal A0 is minimum (negative). At the positions a, c, e, the resistance values of the anisotropic magnetoresistive elements 31a, 31b, 31c, 31d are equal to each other, and the detection signal A0 is “0”. As a result, as shown by a thick solid line in FIG. 3E, the detection signal A0 changes in a sine wave form by 360 degrees for one pole. The error due to the difference in the radial position of the anisotropic magnetoresistive elements 31a and 31d and the anisotropic magnetoresistive elements 31b and 31c with respect to the rotating magnet 21 is canceled by subtraction of the voltage signals V1a and V2a. High detection accuracy.

  As shown in FIG. 3B, the second full bridge circuit 32 also includes four anisotropic magnetoresistive elements 32a, 32b, 32c, and 32d. The anisotropic magnetoresistive elements 32a, 32b, 32c, and 32d are located at the same positions as the anisotropic magnetoresistive elements 31a, 31b, 31c, and 31d in a plane parallel to the rotating surface of the rotating magnet 21. The magnetic sensor 31 and the magnetic sensor 31 are stacked in layers with an insulating film interposed therebetween. That is, the center-of-gravity position C1 in the extending plane of the anisotropic magnetoresistive elements 31a, 31b, 31c, 31d and the center-of-gravity position C2 in the extending plane of the anisotropic magnetoresistive elements 32a, 32b, 32c, 32d. Are on the same straight line perpendicular to the magnetosensitive surface. The anisotropic magnetoresistive elements 32a, 32b, 32c, and 32d are configured similarly to the anisotropic magnetoresistive elements 31a, 31b, 31c, and 31d, but the anisotropic magnetoresistive elements 32a, 32b, The extending directions of 32c and 32d are directions in which the extending directions of the anisotropic magnetoresistive elements 31a, 31b, 31c and 31d are rotated by 45 degrees.

  In the anisotropic magnetoresistive effect elements 32a, 32b, 32c, and 32d thus configured, the anisotropic magnetoresistive effect elements 32a and 32b are connected in series, and a voltage Vcc is applied to both ends thereof. Thus, the voltage at these connection points is taken out as a voltage signal V1b. Further, the anisotropic magnetoresistive elements 32d and 32c are connected in series, and the voltage Vcc is applied to both ends thereof, and the voltage at the connection point is taken out as the voltage signal V2b. These voltage signals V1b and V2b are subtracted by a differential amplifier 34 in an electric circuit described later and output as a detection signal B0 (= V1b−V2b) (see FIG. 4).

  In this case, the center-of-gravity position C2 of the anisotropic magnetoresistive elements 32a, 32b, 32c, and 32d is located at the positions a, b, c, d, and e at equal intervals from the position a corresponding to one pole of the rotating magnet 21 to the position e. When sequentially moving, at positions a and e, the resistance values of the anisotropic magnetoresistive elements 32a and 32c are minimum and the resistance values of the anisotropic magnetoresistive elements 32b and 32d are maximum, so that the detection signal B0 is maximum. (Correct). At the position c, the resistance values of the anisotropic magnetoresistive elements 32b and 32d are minimum and the resistance values of the anisotropic magnetoresistive elements 32a and 32c are maximum, so that the detection signal B0 is minimum (negative). At the positions b and d, the resistance values of the anisotropic magnetoresistive elements 32a, 32b, 32c, and 32d are equal to each other, and the detection signal B0 is “0”. As a result, the detection signal B0 changes in a cosine wave shape (that is, a sine wave shape having a phase delay of 90 degrees with respect to the detection signal A0) as shown by a thin solid line in FIG. Also in this case, the error due to the difference in the radial position of the anisotropic magnetoresistive elements 32a and 32d and the anisotropic magnetoresistive elements 32b and 32c with respect to the rotating magnet 21 is the subtraction of the voltage signals V1b and V2b. This cancels out and the detection accuracy becomes high.

  As described above, the first magnetic sensor 30 has a phase of 90 degrees with one period (N pole or S pole) in the first magnetic pattern by the first and second full bridge circuits 31 and 32. Sinusoidal detection signals A0 and B0 (sine wave signal A0 and cosine wave signal B0) are output. Then, as shown in FIG. 6A, detection signals A0 and B0 having the same period of 16 periods are output from the first magnetic sensor 30 per rotation of the rotating magnet 21. In this case, the center of gravity C1 of the first full bridge circuit 31 (anisotropic magnetoresistive effect elements 31a, 31b, 31c, 31d) and the second full bridge circuit 32 (anisotropic magnetoresistive effect elements 32a, 32b, 32c). , 32d) is located on the same straight line perpendicular to the magnetic sensitive surfaces of the first and second full bridge circuits 31, 32, so that the first and second full bridge circuits 31, 32 have the same size. A change in the magnetic field that changes at this time is detected, and the amplitudes of the detection signals A0 and B0 match.

  The second magnetic sensor 40 also has first and second full bridge circuits 41 and 42 similar to the first and second full bridge circuits 31 and 32 of the first magnetic sensor 30. The voltage signals V1a and V2a from the first full bridge circuit 41 are also subtracted by the differential amplifier 43 in the electric circuit and taken out as a sinusoidal detection signal A1, and the voltage signal from the second full bridge circuit 42 is taken. V1b and V2b are also subtracted by the differential amplifier 44 in the electric circuit, and are extracted as a sine wave (ie, cosine wave) detection signal B1 that is 90 degrees out of phase with the detection signal A1 (see FIG. 4). Accordingly, the second magnetic sensor 40 detects the detection signals A1 and B1 (sine wave signal A1 and cosine wave signal B1) having a phase of 90 degrees with each other at one pole (N pole or S pole) in the second magnetic pattern. ) Is output. However, since the second magnetic pattern is composed of the first block 22a composed of a 9-pole magnetic pattern and the second block 22b composed of a 7-pole magnetic pattern, as shown in FIG. Detection signal A1 and B1 of the same period of 9 periods corresponding to the first block 22a and detection signal A1 and B1 of the same period of 7 periods corresponding to the second block 22b from the second magnetic sensor 40. Will be output.

  The third magnetic sensor 50 also includes first and second full bridge circuits 51 and 52 similar to the first and second full bridge circuits 31 and 32 of the first magnetic sensor 30. The voltage signals V1a and V2a from the first full bridge circuit 51 are also subtracted by the differential amplifier 53 in the electric circuit and taken out as the detection signal A2, and the voltage signals V1b, V2b is also subtracted by the differential amplifier 54 in the electric circuit and taken out as a sine wave (ie, cosine wave) detection signal B2 that is 90 degrees out of phase with the detection signal A2 (see FIG. 4). Therefore, the third magnetic sensor 50 also has one pole (N pole or S pole) in the second magnetic pattern by cooperating with the first and second full bridge circuits 51 and 52 and subtraction in the electric circuit described later. Detection signals A2 and B2 (sine wave signal A2 and cosine wave signal B2) having a 90-degree phase with each other are output. However, in this case as well, the second magnetic pattern is composed of a first block 22a composed of a nine-pole magnetic pattern and a second block 22b composed of a seven-pole magnetic pattern, as shown in FIG. The detection signals A2 and B2 having the same period of 9 periods corresponding to the first block 22a and the detection signals A2 and B2 having the same period of 7 periods corresponding to the second block 22b are second per rotation of the rotating magnet 22. It is output from the magnetic sensor 40. In addition, since the second magnetic sensor 40 and the third magnetic sensor 50 are arranged with an angle difference of 90 degrees, the change point of the cycle of the detection signals A2 and B2 is the change point of the cycle of the detection signals A2 and B2. On the other hand, it differs by 90 degrees per rotation of the rotating magnet 22.

  Next, an electric circuit arranged on the substrate 60 will be described with reference to FIG. The voltage signals V1a and V2a from the first full bridge circuit 31 are supplied to the non-inverting input and the inverting input of the differential amplifier 33, respectively. The differential amplifier 33 subtracts the voltage signal V2a from the voltage signal V1a and outputs it as a detection signal A0. The voltage signals V1b and V2b output from the second full bridge circuit 32 are supplied to the non-inverting input and the inverting input of the differential amplifier 34, respectively. The differential amplifier 34 subtracts the voltage signal V2b from the voltage signal V1b and outputs it as a detection signal B0. Therefore, the first magnetic sensor 30 includes the first and second full bridge circuits 31 and 32 and the differential amplifiers 33 and 34, and the above-described sinusoidal detection signals A0, B0 (sine wave signal A0 and cosine wave signal B0) is output (see FIG. 6A).

  Similarly to the first magnetic sensor 30, the second magnetic sensor 40 is composed of the first and second full bridge circuits 41 and 42 and the differential amplifiers 43 and 44, and has the above-described 90-degree phase. Sinusoidal detection signals A1 and B1 (sine wave signal A1 and cosine wave signal B1) are output. Similarly to the first magnetic sensor 30, the third magnetic sensor 50 is composed of the first and second full bridge circuits 51 and 52 and the differential amplifiers 53 and 54, and has the above-described 90-degree phase. Sinusoidal detection signals A2 and B2 (sine wave signal A2 and cosine wave signal B2) are output.

  An A / D converter 70 is connected to the first to third magnetic sensors 30, 40, 50. The A / D converter 70 A / D converts the detection signals A0, B0, A1, B1, A2, and B2 from the first to third magnetic sensors 30, 40, and 50, and outputs the signals to the signal processing circuit 80. . The signal processing circuit 80 is configured by a computer device including a CPU, a ROM, a RAM, a storage device, and the like, and executes arithmetic processing according to a program corresponding to the flowchart of FIG. In execution of this program, digital signals corresponding to the detection signals A0, B0, A1, B1, A2, and B2 are signal-processed using vernier arithmetic processing to calculate the absolute rotation angle φ3 of the rotary shaft 10. .

  Next, the operation of the rotation detection device configured as described above will be described. When the rotating shaft 10, that is, the rotating magnets 21 and 22 are rotated, detection signals of 16 periods equal in period per rotation of 0 to 360 degrees (corresponding to the first magnetic pattern) of the rotating magnet 21 from the first magnetic sensor 30. A0 and B0 are output (see FIG. 6A). Further, from the second magnetic sensor 40, an output signal of nine periods having the same period per half rotation of 0 to 180 degrees (corresponding to the first block 22a) of the rotating magnet 22, and 180 to 360 degrees (first of the rotating magnet 22). Detection signals A1 and B1 consisting of 7-cycle output signals having the same cycle per half rotation (corresponding to 2 blocks 22b) are output (see FIG. 6B). Furthermore, from the third magnetic sensor 50, an output signal of nine periods having the same period per half rotation of 0 to 90, 270 to 360 degrees of the rotating magnet 22 (corresponding to the first block 22a), and 90 to 90 of the rotating magnet 22 are output. Detection signals A2 and B2 consisting of output signals of seven periods having the same period per half rotation of 270 degrees (corresponding to the second block 22b) are output (see FIG. 6C).

These detection signals A 0, B 0, A 1, B 1, A 2, B 2 are converted into digital signals by the A / D converter 70 and supplied to the signal processing circuit 80. The signal processing circuit 80 starts execution of the program at step S10 in FIG. 5 at the start of measurement of the rotation angle, and then executes a circulation process including steps S12 to S30. In step S12, the signal processing circuit 80 inputs the instantaneous values of the supplied detection signals A0, B0, A1, B1, A2, and B2. Next, in step S14, the signal processing circuit 80 calculates the arc tangent angles θ0, θ1, and θ2 by the arctangent calculation of the following equations 2 to 4 using the detection signals A0, B0, A1, B1, A2, and B2. calculate. These arc tangent angles θ0, θ1, and θ2 change in a sawtooth wave shape with one pole of the first and second magnetic patterns as one cycle. Changes in the arc tangent angles θ0, θ1, and θ2 are shown in FIGS. 7A to 7C, respectively.

After the process of step S14, the signal processing circuit 80 performs the phase difference φ1 between the arc tangent angles θ0 and θ1 in step S16 by the remainder calculation of the following equations 5 and 6 using the arc tangent angles θ0, θ1, and θ2. Then, the phase difference φ2 between the arc tangent angles θ0 and θ2 is calculated.

  The arithmetic expression of mod (x, y) in Equations 5 and 6 represents a surplus operation for obtaining a surplus when x is divided by y. In the calculations of Equations 5 and 6, since y is 2π, the phase differences φ1 and φ2 change from 0 to 2π in radians. However, since y only represents a basic unit, this y may simply be a predetermined constant. For example, if this y is set to 360 degrees instead of 2π, the phase differences φ1 and φ2 change over 0 to 360 degrees. Note that the operations in steps S14 and S16 are vernier operations.

  These phase differences φ1 and φ2 are shown in FIG. 8 corresponding to the rotation angles (0 to 360 degrees) of the rotating magnets 21 and 22. In this case, the phase difference φ1 is a straight line that rises to the right in the first block 22a (range of 0 to 180 degrees), and a straight line that falls to the right in the second block 22b (180 to 360 degrees). This means that in the state where the second magnetic sensor 40 faces the first block 22a, the phase difference φ1 changes on the straight line rising to the right, and the second magnetic sensor 40 faces the second block 22b. In the state, it means that the phase difference φ1 changes on the straight line that descends to the right. On the other hand, the phase difference φ2 is 90 degrees out of phase with the phase difference φ1. That is, the phase difference φ2 is a straight line that rises to the right in the first half (0 to 90 degrees) of the first block 22a and the second half (270 to 360 degrees) of the second block 22b, and the second half (90 of the first block 22a) ˜180 degrees) and the first half of the second block 22b (about 180 to 270 degrees) are straight to the right. The change width of these phase differences φ1 and φ2 is assumed to be K. Note that the change width K is 2π in this embodiment.

  After the processing in step S16, the signal processing circuit 80 subtracts the predetermined value X from the phase difference φ2 in step S18, and determines whether or not the subtraction result φ2-X is “0” or more. In this case, the value X is the value of the phase difference φ2 when the rotation angle θ is 0 degree, that is, when the phase difference φ1 is minimum (the same as the value of the phase difference φ2 when the phase difference φ1 is maximum). Yes, the value is detected and stored separately from this program processing. Further, the value X may be calculated and stored at the start of execution of the program processing or periodically during execution of the program. In the present embodiment, the value X is K / 2, which is half of the change width K. However, when the respective ranges of the first and second blocks 22a and 22b in the second magnetic pattern are not 180 degrees, The value X is different from K / 2, which is half of the change width K.

  The subtraction result φ2-X changes as indicated by a broken line in FIG. 9, and becomes positive in the first block 22a and negative in the second block 22b. If the subtraction result φ2-X is “0” or more, the signal processing circuit 80 determines “Yes” in Step S18, and sets the increase flag UP to “1” in Step S20. If the subtraction result φ2-X is less than “0”, the signal processing circuit 80 determines “No” in Step S18, and sets the increase flag UP to “0” in Step S22. The value of the increase flag UP is indicated by a thick line in FIG. 9 in association with one rotation (0 to 360 degrees) of the rotary magnets 21 and 22. As a result, the increase flag UP indicates that the second magnetic sensor 40 is positioned opposite to the first block 22a and the phase difference φ1 takes a value on a straight line that rises to the right (see FIG. 8). Will show. Further, the increase flag UP indicates by “0” that the second magnetic sensor 40 is positioned opposite to the second block 22b and the phase difference φ1 takes a value on the right-downward straight line (see FIG. 8). become.

  After the processes of steps S20 and S22, the signal processing circuit 80 determines whether or not the increase flag UP is “1” in step S24. If the second magnetic sensor 40 is located facing the first block 22a and the increase flag UP is “1”, the signal processing circuit 80 determines “Yes” in step S24, and in step S26. The phase difference φ1 is set as the absolute rotation angle φ3. On the other hand, if the second magnetic sensor 40 is located opposite to the second block 22b and the increase flag UP is “0”, the signal processing circuit 80 determines “No” in step S24, and step S28. The value 2 · K−φ1 obtained by subtracting the phase difference φ1 from the value 2 · K obtained by doubling the change width K is set as the absolute rotation angle φ3.

  Also in this case, the change width K is a phase difference φ1 corresponding to the 180 ° rotation of the rotating magnets 21 and 22, that is, the maximum value of the phase difference φ1 (equal to the maximum value that is the change width K of the phase difference φ2). Yes, the value is detected and stored in advance. As shown in FIG. 10A, the value K−φ1 is the difference between the maximum value K and the phase difference φ1 in the second block 22b, and the value 2 · K−φ1 (= K + K−φ1) is the maximum. This is a value obtained by folding the phase difference φ1 around the value K. Therefore, the angle range of 180 to 360 degrees of the rotating magnets 21 and 22, that is, the absolute rotation angle φ3 in the state where the second magnetic sensor 40 is located facing the second block 22b is calculated by the process of step S28. . As a result, the absolute rotation angle φ3 that changes over 0 to 2 · K (0 to 4π in the present embodiment) for one rotation (0 to 360 degrees) of the rotating magnets 21 and 22 is calculated. become. The change in the absolute rotation angle φ3 is shown in FIG. FIG. 10C shows the difference between the electrical angle, which is the absolute rotation angle φ3 obtained by the above calculation, and the mechanical angle, which is the actual rotation angle of the rotating magnets 21, 22, that is, the angle error of the absolute rotation angle φ3. Δφ3 is shown. In this embodiment, since the angle ranges of the first and second blocks 22a and 22b are both 180 degrees, the angle error Δφ3 does not occur.

  The reason why the absolute rotation angle φ3 can be detected by the arithmetic processing consisting of the steps S18 to S28 is that the two values of the phase difference φ2 at the two rotation angles θ at which the phase difference φ1 becomes the minimum value and the maximum value coincide with each other. It is assumed that the two values of the phase difference φ1 at the two rotation angles θ at which the phase difference φ2 is the minimum value and the maximum value are the same. In step S18, the phase difference φ2 at the rotation angle θ at which the phase difference φ1 is the minimum value and the maximum value is the value X. Therefore, in the calculation of the absolute rotation angle φ3, the phase difference φ1 increases from the minimum value to the maximum value in the angle range of the phase difference φ2 that is not less than the value X, and in the angle range of the phase difference 2 that is not more than the value X, The phase difference φ1 uses a decrease from the maximum value to the minimum value. In addition, the said premise is the fact confirmed by many simulation results including the case where both angle ranges of the 1st and 2nd blocks 22a and 22b of a 2nd magnetic pattern differ.

After the processes in steps S26 and S28, the signal processing circuit 80 executes an interpolation calculation process using the absolute rotation angle φ3 and the arctangent angle θ0 in step S30. Specifically, as shown in FIG. 11, the calculated absolute rotation angle φ3 is represented by a predetermined number of bits to be the upper bits of the absolute rotation angle φ3 ′ after interpolation, and the arctangent angle θ0 (= tan ^−1). (A0 / B0)) is represented by a predetermined number of bits and is the lower bit of the absolute rotation angle φ3 ′ after interpolation (the lower bit following the least significant bit of the absolute rotation angle φ3). For example, when the absolute rotation angle φ3 ′ after the interpolation is 15 bits, the upper 10 bits of the absolute rotation angle φ3 ′ after the interpolation is the absolute rotation angle φ3 represented by 10 bits, and the absolute rotation angle after the interpolation The lower tangent angle θ0 in which the lower 5 bits of φ3 ′ are represented by 5 bits is set to φ0 (φ3 ′ = φ3 · 2 ⁵ + θ0). Thereby, the rotation angle of the rotating magnets 21 and 22 can be expressed with a fine interval (angle), that is, with high resolution, and a high-accuracy rotation detecting device is realized as a whole.

  After the process of step S30, the signal processing circuit 80 returns to the execution of step S12, and thereafter repeats the processes of steps S12 to S30 to calculate the rotation angle φ3 ′ obtained by interpolating the absolute rotation angle φ3. Keep doing. Note that if the high-resolution absolute rotation angle φ3 'is not required, the process of step S30 is not necessary.

  In the rotation detection device configured and operated as in the above embodiment, the first magnetic sensor 30 detects a change in the magnetic field due to the first magnetic pattern, and has a phase of one cycle per pole of the first magnetic pattern. Two different detection signals A0 and B0 are output, and the second and third magnetic sensors 40 and 50 detect a change in the magnetic field due to the second and third magnetic patterns, and detect one pole of the second and second magnetic patterns. Two detection signals A1, B1, A2, and B2 having different phases in one cycle are output. Then, the signal processing circuit 80 performs an absolute rotation angle of the rotary shaft 10 by vernier calculation processing (inverse tangent calculation processing and phase difference calculation processing) using detection signals from the first to third magnetic sensors 30, 40, 50. Calculate φ3. In this case, since the absolute rotation angle φ3 is calculated using the detection signals A0, B0, A1, B1, A2, and B2 of one cycle for each pole of the first to third magnetic patterns, the absolute rotation angle φ3 with high resolution. And the absolute rotation angle φ3 of the rotary shaft 10 can be detected with high accuracy. Further, since the first to third magnetic sensors 30, 40, 50 are not provided on the extension line of the central axis of the rotating shaft 10, the first to third magnetic sensors 30, 40, 50 can be applied to a rotating body having a structure that allows the rotating shaft 10 to pass therethrough. Of course, the present invention can also be applied to a rotating body having a structure in which the rotating shaft passes therethrough.

  In the above-described embodiment, the signal processing circuit 80 further calculates the interpolation absolute rotation angle φ3 ′ by executing the interpolation calculation process of the absolute rotation angle φ3 by using the calculated arctangent angle θ0. Therefore, the absolute rotation angle φ3 of the rotating shaft 10 can be made high resolution.

  Moreover, in the said embodiment, 1st thru | or 3rd magnetic sensor 30,40,50 is 1st full bridge circuit 31,41,51 which consists of anisotropic magnetoresistive effect element 31a, 31b, 31c, 31d, The voltage signal detected by the first to third magnetic sensors 30, 40, and 50 is constituted by the second full bridge circuits 32, 42, and 52 including the anisotropic magnetoresistive elements 32 a, 32 b, 32 c, and 32 d. The accuracy of V1a, V2a, V1b, and V2b is increased, and the absolute rotation angle φ3 is highly accurate.

  Further, in each of the first to third magnetic sensors 30, 40, 50, anisotropic magnetoresistive elements 31a, 31b, 31c, 31 constituting the first full bridge circuits 31, 41, 51, and the second full The anisotropic magnetoresistive elements 32a, 32b, 32c, and 32d that constitute the bridge circuits 32, 42, and 52 are arranged so as to overlap each other through an insulating film, and the anisotropic magnetoresistive elements 31a, 31b, 31c, and 31 are arranged. The center-of-gravity position C1 passes through the center-of-gravity position C2 of the anisotropic magnetoresistive elements 32a, 32b, 32c, and 32d, and is orthogonal to the plane on which the anisotropic magnetoresistive elements 31a, 31b, 31c, and 31 are disposed. It was located on a straight line. As a result, the first and second full bridge circuits 31, 32, 41, 42, 51, 52 detect changes in the magnetic field that change with the same magnitude, and the first to third magnetic sensors 30, 40 are detected. , 50, the voltage signals V1a, V2a, V1b, V2b detected with higher accuracy and the absolute rotation angle φ3 with higher accuracy.

  In the above embodiment, the rotating magnets 21 and 22 are arranged in two rows in the rotating shaft direction and have the same outer diameter, and the rotating magnets 21 and 22 are arranged outside the outer peripheral surfaces of the rotating magnets 21 and 22. A flat plate-like substrate 60 extending in the circumferential direction at the boundary position, and fixing the first magnetic sensor 30 to the upper surface of the substrate 60 so as to face the first magnetic pattern of the rotating magnet 21, and The second and third magnetic sensors 30 and 40 are fixed to the lower surface of the substrate 60 so as to face the second magnetic pattern. Thereby, since the 1st thru | or 3rd magnetic sensors 30, 40, and 50 can be mounted on the one board | substrate 60, the structure of a rotation detection apparatus becomes simple. Further, since the first magnetic sensor 30 is disposed between the second magnetic sensor 40 and the third magnetic sensor 50 in the circumferential direction of the rotary magnets 21 and 22, the extending angle of the substrate 60 in the circumferential direction. Since the first to third magnetic sensors 30, 40, and 50 can be mounted on the substrate 60 only by making the angle slightly larger than 90 degrees, the substrate 60 can be reduced in size.

b. Regarding the number of poles and the magnetization angle of the first and second magnetic patterns In the above embodiment, the angle ranges of the first and second blocks 22a and 22b of the second magnetic pattern are both 180 degrees. In addition, the number of poles n of the first magnetic pattern is set to “16”, and the number of poles n1 and n2 of the first and second blocks 22a and 22b of the second magnetic pattern are set to “9” and “7”, respectively. did. However, as described above, according to the present invention, if the sum of the angle ranges of the first and second blocks 22a and 22b is 360 degrees, the angle range of the first and second blocks 22a and 22b is not 180 degrees. Also good. Further, in the number n of poles of the first magnetic pattern and the number of poles n1 and n2 of the first and second blocks 22a and 22b, the number of poles n is an even number, and the number of poles n1 and n2 are both even or odd. Therefore, it is only necessary that n = n1 + n2.

  This point will be described with reference to FIGS. In FIG. 12 and FIG. 13, in order to make the drawings easy to see, the number of poles n of the first magnetic pattern is set to “8”, and the total value n1 + n2 of the number of poles n1 and n2 of the first and second blocks 22a and 22b is set to “ 8 ".

  First, a case where the angle range of the first and second blocks 22a and 22b is shifted from 180 degrees will be described. In FIG. 12A, the pole numbers n1 and n2 of the first and second blocks 22a and 22b are “5” and “3”, and the boundary between the first block 22a and the second block 22b is the first magnetic pattern. The case where it exists in the 5th magnetic pole range is shown. In this case, the inverse tangent angles θ0, θ1, and θ2 change as shown in FIG. 12B, and the end point of the fifth cycle of the inverse tangent angle θ1 is the end point of the fourth cycle and the fifth cycle of the inverse tangent angle θ0. The end point of the fifth cycle of the arc tangent angle θ2 is located between the end point of the second cycle and the end point of the third cycle of the arc tangent angle θ0. Therefore, the phase differences φ1 and φ2 change back and forth between 0 and K as shown in FIG. 12C, and the phase difference φ1 is between the end point of the fourth cycle and the end point of the fifth cycle of the arctangent angle θ0. It becomes the maximum value at, and turns back from an increasing trend to a decreasing trend. This turning point is designated as TP. Also in this case, since the phase difference φ2 changes 90 degrees behind the phase difference φ1, the increase flag UP is inverted from “1” to “0” at the turnaround point TP.

  In this case, since the phase difference φ1 with respect to the arc tangent angle θ0 of the end point position of the fifth cycle of the arc tangent angle θ1 is a value between 0 and 2π, the value K that is the phase difference φ1 of the turning point TP is 0 to 0. The phase difference φ1 is a value between 2π, and the phase difference φ1 is only one reciprocation between 0 and K in one rotation of the rotating magnets 21 and 22. Therefore, the phase difference φ1 represents the rotation angle of the rotating magnets 21 and 22. It will be. However, since the turning point TP is not at the 180 degree position, the inclination when the phase difference θ1 increases is smaller than the inclination when the phase difference θ1 decreases, and the absolute rotation angle φ3 obtained by turning back the phase difference φ1 is as shown in FIG. As shown by the solid line, the inclination angle changes at the turning point TP. On the other hand, in the case of the above embodiment, the turning point TP is at the 180 degree position, and the slopes when the phase difference φ1 increases and decreases are equal, so the absolute rotation angle φ3 is the broken line in FIG. As shown in Therefore, in this case, the detection accuracy of the absolute rotation angle φ3 is deteriorated as compared with the case of the above embodiment. This means that it is desirable to set the angle range of the first and second blocks 22a and 22b of the second magnetic pattern to a value close to 180 degrees.

  Further, as described above, the value K that is the phase difference φ1 of the turning point TP is a value between 0 and 2π, and is smaller than 2π. On the other hand, in the case of the above embodiment, the value K, which is the phase difference φ1 of the turning point TP, is 2π. Therefore, in this case, the amount of change in the absolute rotation angle φ3 per rotation of the rotating magnets 21 and 22 is smaller than in the case of the above embodiment, and the detection accuracy of the absolute rotation angle φ3 is deteriorated. This means that the turn-back point TP matches the end point position of the fifth cycle of the arctangent angle θ1 with the end point position of the fourth cycle of the arctangent angle θ0, that is, the first and second blocks 22a and 22b of the second magnetic pattern. Is equal to the end position of the pole of the first magnetic pattern, which means that the amount of change of the absolute rotation angle φ3 per rotation of the rotating magnets 21 and 22 can be maximized. Further, increasing the magnetization angle λ1 to bring the turn point TP, that is, the end point position of the fifth cycle of the arctangent angle θ1, closer to the end point position of the fifth cycle of the arctangent angle θ0 is a value K (phase difference θ1 −θ0) is gradually reduced, which means that the amount of change in the absolute rotation angle φ3 per rotation of the rotary magnets 21 and 22 is reduced to deteriorate the detection accuracy of the absolute rotation angle φ3. Since the magnetization angle λ1 of the first block 22a is smaller than the magnetization angle λ0 of the first magnetic pattern, the fifth cycle of the inverse tangent angle θ1 cannot reach the fifth cycle of the inverse tangent angle θ0. .

  On the other hand, when the end point position of the fifth cycle of the turning point TP, that is, the arc tangent angle θ1, is set to the left side of the end point position of the fourth cycle of the arc tangent angle θ0, that is, the 5 cycles of the arc tangent angle θ1 are the arc tangent angle θ0. Shorter than 4 periods, the phase difference φ1 (= θ1−θ0) of the turning point TP exceeds 2π in the fifth period of the arctangent angle θ1. Therefore, in this case, the arc tangent angle θ1 decreases rapidly before reaching the turn-back point TP, and the absolute rotation angle φ3 cannot be detected.

  To summarize the above points, when the number of poles n is “8” and the number of poles n1 is “5”, the end point position of the fifth cycle of the arctangent angle θ1 is P5min˜ in FIG. The absolute rotation angle φ3 can be detected on the condition that the range of P5max, that is, the 5 cycles of the arctangent angle θ1 is a range of 4 cycles or more and less than 5 cycles of the arctangent angle θ0. When the five cycles of the arc tangent angle θ1 and the four cycles of the arc tangent angle θ0 coincide, the absolute rotation angle φ3 changes to the maximum.

  Next, the case where the pole number n is “8” and the pole number n1 is “4” will be described. In this case, the end point position of the fourth cycle of the arctangent angle θ1 is as shown in FIG. The absolute rotation angle φ3 can be detected on the condition that the range of P4min to P4max, that is, the four cycles of the arctangent angle θ1 is in the range of 3 cycles or more and less than 4 cycles of the arctangent angle θ0. Also in this case, the absolute rotation angle φ3 changes to the maximum when the four periods of the arctangent angle θ1 coincide with the three periods of the arctangent angle θ0.

  The case where the number of poles n is “8” and the number of poles n1 is “6” will be described. In this case, the end point position of the sixth cycle of the arctangent angle θ1 is P6min in FIG. The absolute rotation angle φ3 can be detected on the condition that the range of .about.P6max, that is, the 6 cycles of the arctangent angle θ1 is the range of 5 cycles or more and less than 6 cycles of the arctangent angle θ0. Also in this case, the absolute rotation angle φ3 changes to the maximum when the six periods of the arctangent angle θ1 coincide with the five periods of the arctangent angle θ0.

  Further, the case where the number of poles n is “8” and the number of poles n1 is “7” will be described. In this case, the end point position of the seventh cycle of the arctangent angle θ1 is P7min in FIG. The absolute rotation angle φ3 can be detected on the condition that the range of .about.P7max, that is, the 6 cycles of the arc tangent angle θ1 is 6 cycles or more and less than 7 cycles of the arc tangent angle θ0. Also in this case, the absolute rotation angle φ3 changes to the maximum when the seven periods of the arctangent angle θ1 coincide with the six periods of the arctangent angle θ0.

  Thus, when the pole number n of the first magnetic pattern is “8”, the pole number n1 of the first block 22a of the second magnetic pattern is “4”, “5”, “6”, and “7”. In any case, the absolute rotation angle φ3 can be detected if the following condition is satisfied. In other words, the angle of the first block 22a, that is, the value n1 · λ1 obtained by multiplying the number of poles n1 by the magnetization angle λ1 is the angle of the first magnetic pattern having the number of poles n1-1 smaller by “1” than the number of poles n1. A value obtained by multiplying the number of poles n1-1 by the magnetization angle λ0 (n1-1) · λ0 or more, and a value obtained by multiplying the angle of the first magnetic pattern of the number of poles n1, ie, the number of poles n1 by the magnetization angle λ0. If it is less than λ0, the absolute rotation angle φ3 can be detected. In this case, since the number of poles n1 is assumed to be equal to or more than the number of poles n2 of the second block 22b, the number of poles n1 cannot be “1”, “2”, or “3”. In other words, since the first and second blocks 22a and 22b are relative, it is not necessary to consider “1”, “2”, and “3” as the number of poles n1.

  However, when the number of poles n1 is set to “4”, “6”, or “7”, the turning point TP rotates as shown in FIG. 13B compared to the case where the number of poles n1 is “5”. The deviation of the magnets 21 and 22 from the 180 degree position increases, and the angle error increases. FIG. 13C shows values when the end point position of the fifth cycle of the arctangent angle θ1 is changed from P5min to P5max in FIG. 13A when the number of poles n1 is “5”. The change range of K is shown. As a result, as described above, the change range of the phase difference φ1 and the absolute rotation angle φ3 is increased as the end point position of the fifth cycle of the arctangent angle θ1 approaches the end point position of the fourth cycle of the arctangent angle θ0. Can do. This is the same when the number of poles n1 is set to “4”, “6”, and “7”, and the end point positions of the fourth, sixth, and seventh periods of the arc tangent angle θ1. Are closer to the end positions of the third period, the fifth period, and the sixth period of the degree θ0, respectively, the change ranges of the phase difference φ1 and the absolute rotation angle φ3 can be increased. Furthermore, although the case where the number of poles n is set to “8” has been described in the above example, the same theory holds true when the number of poles n is set to an even number other than “8”.

  Next, a theoretical description will be given of the number of poles and the magnetization angle at which the absolute rotation angle φ3 can be detected. Here, the number of poles and the magnetization angle of the first magnetic pattern are n and λ0. Further, the difference in the number of poles of the first and second blocks 22a, 22b of the second magnetic pattern is 2 · a, and the number of poles and the magnetization angle of the first block 22a of the second magnetic pattern are (n / 2) + a (= N1) and λ1, and the number of poles and the magnetization angle of the second block 22b of the second magnetic pattern are (n / 2) −a (= n2) and λ2. The value n is an even number, and the value a is a natural number including “0” less than n / 2.

In this case, as is apparent from the above description, the following Equation 7 may be established to enable detection of the absolute rotation angle φ3. In this case, the following equation 8 is also established.

Substituting the equation 8 into the equation 7 for modification, the following equation 9 is established. The number 9 is the same as the relationship between the number n of the first magnetic pattern, the number (n / 2) + a of the first block 22a of the second magnetic pattern, and the landing angles λ0 and λ1. This can also be derived by considering the relationship between the number n of poles of one magnetic pattern, the number of poles (n / 2) -a of the second block 22b of the second magnetic pattern, and the landing angles λ0 and λ2.

したがって、前記数１０，１１が成立すれば、絶対回転角φ３の検出が可能となる。 Then, if Equation 7 and Equation 9 are modified, the following Equation 10 and Equation 11 are established.

Therefore, if Equations 10 and 11 are established, the absolute rotation angle φ3 can be detected.

  However, as can be seen from the above description, if the difference a between the number of poles of the first block 22a and the number of poles of the second block 22b is “0” or “2”, the turning point TP is set to 180 degrees or 180 degrees. Can be close. When the difference a is “0”, the value K (that is, the phase differences φ1, φ2) approaches 2π as the turning point TP is moved away from 180 degrees. On the other hand, when the difference a is “2”, the value K (that is, the phase differences φ1 and φ2) approaches 2π as the turning point TP approaches 180 degrees. Therefore, in order to increase the resolution of the absolute rotation angle while maintaining high accuracy, the difference a is preferably “2”.

c. Simulation Example In the description of the above embodiment, and the number of poles and the magnetization angle of the first and second magnetic patterns, no limitation was imposed on the magnetization angles λ0, λ1, and λ2. However, since there is a problem with the accuracy of the magnetization angles λ0, λ1, and λ2 in actual production, a plurality of simulation results performed considering the limitations on the magnetization angles λ0, λ1, and λ2 in commercialization will be described. Keep it.

c1. Simulation examples capable of detecting the absolute rotation angle φ3 First, first to third simulation examples capable of detecting the absolute rotation angle φ3 will be described. As a first simulation example, the number of poles n of the first magnetic pattern is “16”, and the number of poles n1 and n2 of the first and second blocks 22a and 22b in the second magnetic pattern are “9” and “7”, respectively. It is. The magnetization angle λ0 of the first magnetic pattern is 22.5 degrees, the magnetization angle λ1 of the first block 22a of the second magnetic pattern is 20.05 degrees, and the second block 22b of the second magnetic pattern. The magnetization angle λ2 is 25.65 degrees. This condition satisfies the conditions of Equations 10 and 11 above. The angle range of the first block 22a is 180.45 degrees, the angle range of the second block 22b is 179.55 degrees, and both angle ranges are extremely close to 180 degrees. Therefore, the phase differences φ1, φ2, the increase flag UP, the absolute rotation angle φ3, and the angle error Δφ3 are substantially the same as those in FIGS. 10A, 10B, and 10C, and the change range and error of the absolute rotation angle φ3. Is also extremely small.

  As a second simulation example, the number of poles n of the first magnetic pattern is “16”, and the number of poles n1 and n2 of the first and second blocks 22a and 22b in the second magnetic pattern are “8” and “8”, respectively. It is. The magnetization angle λ0 of the first magnetic pattern is 22.5 degrees, the magnetization angle λ1 of the first block 22a of the second magnetic pattern is 19.75 degrees, and the second block 22b of the second magnetic pattern. The magnetization angle λ2 is 25.25 degrees. This condition also satisfies the conditions of Equations 10 and 11 above. The angle range of the first block 22a is 158.00 degrees, and the angle range of the second block 22b is 202.00 degrees.

  FIGS. 14A, 14B, and 14C show the phase differences φ1, φ2, the increase flag UP, the absolute rotation angle φ3, and the alignment angle error Δφ3 in the second simulation example, respectively. In this case, the turning point TP of the phase difference φ1 shifts from 180 degrees to the smaller side, the inclination of the absolute rotation angle also changes at the turning point TP, and the angle error Δφ3 becomes relatively large. Note that the change ranges of the phase difference φ1 and the absolute rotation angle φ3 are also smaller than in the first simulation example. As a result, the detection accuracy in the second simulation example is worse than the detection accuracy in the first simulation example. However, the rotation detection device according to the second simulation example is effective for an application (for example, a robot arm) that requires the accuracy of a specific angle range without requiring 360 degrees as the rotation angle θ. .

  As a third simulation example, the number of poles n of the first magnetic pattern is “16”, and the number of poles n1 and n2 of the first and second blocks 22a and 22b in the second magnetic pattern are “10” and “6”, respectively. Is. The magnetization angle λ0 of the first magnetic pattern is 22.5 degrees, the magnetization angle λ1 of the first block 22a of the second magnetic pattern is 20.37 degrees, and the second block 22b of the second magnetic pattern. The magnetization angle λ2 is 26.05 degrees. This condition also satisfies the conditions of Equations 10 and 11 above. The angle range of the first block 22a is 203.70 degrees, and the angle range of the second block 22b is 156.30 degrees.

  FIGS. 15A, 15B, and 15C show the phase differences φ1, φ2, the increase flag UP, the absolute rotation angle φ3, and the alignment angle error Δφ3 in the third simulation example, respectively. In this case, the turning point TP of the phase difference φ1 shifts from 180 degrees to the larger side, the inclination of the absolute rotation angle also changes at the turning point TP, and the angle error Δφ3 becomes relatively large. Note that the change ranges of the phase difference φ1 and the absolute rotation angle φ3 are also smaller than in the first simulation example. As a result, the detection accuracy in this third simulation example is worse than that in the first simulation example. However, the rotation detection device according to the third simulation example is effective for an application (for example, a robot arm) that requires the accuracy of a specific angle range without requiring 360 degrees as the rotation angle θ. .

c2. Next, fourth to sixth simulation examples in which the absolute rotation angle φ3 cannot be detected will be described. As a fourth simulation example, the pole number n of the first magnetic pattern is “16”, and the pole numbers n1 and n2 of the first and second blocks 22a and 22b in the second magnetic pattern are “9” and “7”, respectively. It is. The magnetization angle λ0 of the first magnetic pattern is 22.5 degrees, the magnetization angle λ1 of the first block 22a of the second magnetic pattern is 19.970 degrees, and the second block 22b of the second magnetic pattern. The magnetization angle λ2 is 25.753 degrees. This condition does not satisfy the conditions of Equations 10 and 11. The angle range of the first block 22a is 179.73 degrees, and the angle range of the second block 22b is 180.27 degrees.

  FIGS. 16A and 16B show the phase difference φ1, the increase flag UP, and the absolute rotation angle φ3 in the fourth simulation example, respectively. In this case, at the position where the phase difference φ1 reaches the maximum value, the turn-back point TP does not exist and the increase flag UP also changes from “1” to “0” in the range of the rotation angle of 180 degrees. Change times. The absolute rotation angle φ3 has a rotation angle that changes rapidly. Therefore, in the fourth simulation example, the absolute rotation angle φ3 cannot be detected.

  As a fifth simulation example, the pole number n of the first magnetic pattern is “18”, and the pole numbers n1 and n2 of the first and second blocks 22a and 22b in the second magnetic pattern are “10” and “8”, respectively. Is. The magnetization angle λ0 of the first magnetic pattern is 20.0 degrees, the magnetization angle λ1 of the first block 22a of the second magnetic pattern is 17.930 degrees, and the second block 22b of the second magnetic pattern. Is 22.588 degrees. This condition also does not satisfy the conditions of Equations 10 and 11. The angle range of the first block 22a is 179.30 degrees, and the angle range of the second block 22b is 180.70 degrees. FIGS. 17A and 17B show the phase difference φ1, the increase flag UP, and the absolute rotation angle φ3 in the fifth simulation example, respectively. Also in this case, as in the case of the fourth simulation example, the absolute rotation angle φ3 cannot be detected.

  As a sixth simulation example, the number of poles n of the first magnetic pattern is “20”, and the number of poles n1 and n2 of the first and second blocks 22a and 22b in the second magnetic pattern are “11” and “9”, respectively. Is. The magnetization angle λ0 of the first magnetic pattern is 18.0 degrees, the magnetization angle λ1 of the first block 22a of the second magnetic pattern is 16.310 degrees, and the second block 22b of the second magnetic pattern. Is 20.066 degrees. This condition also does not satisfy the conditions of Equations 10 and 11. The angle range of the first block 22a is 179.41 degrees, and the angle range of the second block 22b is 180.59 degrees. FIGS. 18A and 18B show the phase difference φ1, the increase flag UP, and the absolute rotation angle φ3 in the sixth simulation example, respectively. Also in this case, as in the case of the fourth simulation example, the absolute rotation angle φ3 cannot be detected.

c3. Example of simulation showing change range of detectable absolute rotation angle φ3 Next, the absolute rotation angle φ3 can be detected, but when the relationship between the magnetization angles λ1 and λ2 is different, that is, the folding point TP is changed. Next, seventh to ninth simulation examples will be described. In any of the seventh to ninth simulation examples, the pole number n of the first magnetic pattern is “16”, and the pole numbers n1 and n2 of the first and second blocks 22a and 22b in the second magnetic pattern are respectively “9” and “7”, and the magnetization angle λ0 of the first magnetic pattern is 22.5 degrees.

  In the seventh simulation example, the magnetization angle λ1 of the first block 22a of the second magnetic pattern is 20.010 degrees, and the magnetization angle λ2 of the second block 22b of the second magnetic pattern is 25.701 degrees. This condition satisfies the conditions of Equations 10 and 11 above. The angle range of the first block 22a is 180.09 degrees, and the angle range of the second block 22b is 179.91 degrees.

  In the eighth simulation example, the magnetization angle λ1 of the first block 22a of the second magnetic pattern is 20.690 degrees, and the magnetization angle λ2 of the second block 22b of the second magnetic pattern is 24.827 degrees. This condition also satisfies the conditions of Equations 10 and 11 above. The angle range of the first block 22a is 186.21 degrees, and the angle range of the second block 22b is 173.79 degrees.

  In the ninth simulation example, the magnetization angle λ1 of the first block 22a of the second magnetic pattern is 21.200 degrees, and the magnetization angle λ2 of the second block 22b of the second magnetic pattern is 24.171 degrees. This condition also satisfies the conditions of Equations 10 and 11 above. The angle range of the first block 22a is 190.80 degrees, and the angle range of the second block 22b is 169.20 degrees.

  FIG. 19 shows changes in the absolute rotation angle φ3 in the seventh to ninth simulation examples. In this case, the change range of the absolute rotation angle φ3 gradually decreases from the seventh simulation example toward the ninth simulation. This is because, as described above, the maximum value K of the phase difference φ1 gradually decreases from 2π as the position TP is turned back from 180 degrees (see the arrow in the figure) (see FIG. 13). Accordingly, the seventh to ninth simulation results are in agreement with the above-described relationship between the magnetization angles λ1 and λ2 and the pole numbers n1 and n2.

d. Modifications The embodiment of the present invention has been described above. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

d1. Modified Example Regarding Magnetoresistive Element In the first to third magnetic sensors 30, 40, 50 of the above embodiment, the first full bridge circuit 31, 41, 51 is composed of four anisotropic magnetoresistive elements (first full resistance element). In the case of the bridge circuit 31, the anisotropic magnetoresistive effect elements 31a, 31b, 31c, and 31d) are configured by full-bridge connection, and the second full-bridge circuits 32, 42, and 52 are formed by four anisotropic elements. The magnetoresistive effect element ((in the case of the second full bridge circuit 32, anisotropic magnetoresistive effect elements 32a, 32b, 32c, 32d) is configured by full bridge connection. The first full bridge circuit 31, 41, 51 and the second full bridge circuit 32, 42, 52 have one cycle per pole of the first and second magnetic patterns, and the phases are different by 90 degrees. As long as it outputs a pair of sinusoidal detection signals, the full bridge circuit may not be composed of anisotropic magnetoresistive elements, but may be composed of other magnetoresistive elements.

For example, the first full bridge circuits 31, 41, 51 and the second full bridge circuits 32, 42, 52 may be constituted by the following magnetoresistive elements (1) to (3).
(1) Artificial lattice type magnetoresistive element composed of a multilayer film of a ferromagnetic layer and a nonmagnetic layer (2) Metal having nm size fine particles composed of a ferromagnetic metal and a grain boundary phase composed of a nonmagnetic metal Metal-based nanogranular magnetoresistive element (3) Metal-insulator nanogranular magnetoresistive element comprising nanometer-sized ferromagnetic metal alloy fine particles and a grain boundary phase made of a nonmagnetic insulating material. ), The anisotropy is less than that of the anisotropic magnetoresistive element of the above embodiment. Therefore, increase the aspect ratio of the element or place a magnetic material having high permeability near the element. Therefore, the anisotropy may be increased by the magnetic flux collecting effect.

d2. Modified Examples of Arrangement of Magnetoresistive Elements In the first to third magnetic sensors 30, 40, 50 of the above-described embodiment, the first full bridge circuits 31, 41, 51 and the second full bridge circuits 32, 42, 52 are provided. Are stacked at the same position, and the first plane on which the four anisotropic magnetoresistive elements of the first full bridge circuits 31, 41, 51 are arranged, and the four pieces of the second full bridge circuits 32, 42, 52. Of the four anisotropic magnetoresistive elements of the first full-bridge circuits 31, 41, 51 (hereinafter simply referred to as the first plane). 1 is the center of gravity position C2 of the four anisotropic magnetoresistive elements of the second full bridge circuits 32, 42, 52 (hereinafter simply referred to as the center of gravity position C2 of the second full bridge circuit). ) And the second plane ( And on the straight line perpendicular to the first plane). That is, the gravity center position C1 of the first full bridge circuit and the gravity center position C2 of the second full bridge circuit are located at the same coordinate position of the two-dimensional coordinates constituting the first and second planes.

  However, instead of this, a full bridge circuit having the same configuration as that of the first full bridge circuit 31 is rotated by 45 degrees to form the second full bridge circuit 32, and both the center of gravity positions C1 and C2 are made to coincide with each other as described above. The first magnetic sensor 30 may be configured by overlapping the full bridge circuit 31 and the second full bridge circuit 32 rotated by 45 degrees. Conversely, the full bridge circuit having the same configuration as the second full bridge circuit 32 is rotated by 45 degrees to form the first full bridge circuit 31, and both the center of gravity positions C1 and C2 are made coincident as described above and rotated by 45 degrees. The first magnetic sensor 30 may be configured by overlapping the first full-bridge circuit 31 and the second full-bridge circuit 32 that have been made to overlap each other. The second and third magnetic sensors 40 and 50 may be configured in the same manner as described above.

  Further, the four anisotropic magnetoresistive elements 31a, 31b, 31c, 31d constituting the first full bridge circuit 31 (or the first full bridge circuits 41, 51) and the second full bridge circuit 32 (or the first full bridge circuit 41, 51). The four anisotropic magnetoresistive elements 32a, 32b, 32c, 32d constituting the two full bridge circuits 42, 52) are arranged on the same plane, and the center of gravity position C1 of the first full bridge circuit and the second You may make it make the gravity center position C2 of a full bridge circuit correspond. Hereinafter, an arrangement example of four anisotropic magnetoresistive elements 31a, 31b, 31c, 31d and four anisotropic magnetoresistive elements 32a, 32b, 32c, 32d provided on the same plane will be described. However, “upper and lower” and “left and right” in this case indicate a positional relationship on the drawing.

  For example, as shown in FIG. 20 (a), anisotropic magnetoresistive elements 32a and 32c are arranged above and below the center of gravity position Co (same as the center of gravity positions C1 and C2). Anisotropic magnetoresistive elements 31a and 31b are arranged above and below the center of gravity Co on the right side of 32a and 32c, and anisotropic magnetoresistive elements 31d and 31c are arranged on the left side of the anisotropic magnetoresistive elements 32a and 32c. 31c is arranged above and below the center of gravity position Co, and the anisotropic magnetoresistive element 32a is arranged on the right side of the anisotropic magnetoresistive elements 31a and 31b with the center of gravity position Co as the center. An anisotropic magnetoresistance effect element 32b is arranged on the left side of the resistance effect elements 31d and 31c with the center of gravity position Co as the center.

  Further, as shown in FIG. 20B, the anisotropic magnetoresistive elements 32a and 32d are arranged on the left and right sides of the center of gravity position Co above the center of gravity position Co so that the anisotropic magnetoresistive elements 31a and 31a, 31d is arranged on the lower side of the center of gravity position Co on the right and left sides of the center of gravity position Co, and the anisotropic magnetoresistive elements 31b and 31c are arranged on the upper side of the center of gravity position Co with respect to the anisotropic magnetoresistive elements 32a and 32d. The anisotropic magnetoresistive elements 32b and 32c may be arranged on the left and right outer sides of the anisotropic magnetoresistive elements 31a and 31d below the gravity center position Co.

  Also, as shown in FIG. 20 (c), the anisotropic magnetoresistive elements 32d, 31d, 32c, 31a, 32b, 31b, 32a, 31c are arranged clockwise from above about the center of gravity position Co. May be.

  Also, as shown in FIG. 20 (d), anisotropic magnetoresistive elements 31d, 31c, 31b, 31a are arranged clockwise from above about the center of gravity position Co, and the anisotropic magnetoresistive elements The 32a and 32b and the anisotropic magnetoresistive elements 32d and 32c may be arranged on the left and right sides of the center of gravity center Co outside the anisotropic magnetoresistive elements 31d, 31c, 31b and 31a. Also by these, the detection signals A0, B0, A1, B1, A2, and B2 output from the first to third magnetic sensors 30, 40, and 50 are the same as those in the above embodiment.

  In the modified example as described above, in each of the first to third magnetic sensors 30, 40, 50, the plurality of anisotropic magnetoresistive elements 31a, 31b, 31c constituting the first bridge circuits 31, 41, 51 are provided. , 31d and a plurality of anisotropic magnetoresistive elements 32a, 32b, 32c, 32d constituting the second bridge circuits 32, 42, 52 are arranged in the same plane, and a plurality of anisotropic magnetoresistive effects are arranged. The centroid position C1 of the elements 31a, 31b, 31c, 31d and the centroid position C2 of the plurality of anisotropic magnetoresistive elements 32a, 32b, 32c, 32d are made to coincide with each other. Thus, as in the case of the above-described embodiment, the first and second full bridge circuits 31, 32, 41, 42, 51, and 52 detect changes in the magnetic field that change with the same magnitude. The accuracy of each of the two detection signals A0, B0, A1, B1, A2, and B2 output from the third magnetic sensors 30, 40, and 50 is improved, and the detected absolute rotation angle φ3 of the rotary shaft 10 is highly accurate. It becomes. Further, since the plurality of anisotropic magnetoresistive elements 31a, 31b, 31c, 31d and the plurality of anisotropic magnetoresistive elements 32a, 32b, 32c, 32d are arranged in the same plane, the first In the manufacturing process of the third magnetic sensor 30, 40, 50, the first and second full bridges 31, 32, 41, 42, 51, 52 can be manufactured simultaneously in one manufacturing process. There is also an effect that 30, 40, 50 can be manufactured easily and inexpensively.

  In the first to third magnetic sensors 30, 40, 50 according to this modification, the artificial lattice type magnetoresistive element, the metal-metal nanogranular magnetoresistive element or the genus-insulator of the above (1) to (3) are also used. The first and second full bridges 31, 32, 41, 42, 51, 52 may be configured using systematic nano-granular magnetoresistive elements.

d3. In the above embodiment, the first to third magnetic sensors 30, 40, and 50 are configured by the first full bridge circuits 31, 41, and 51 and the second full bridge circuits 32, 42, and 52, respectively. I did it. However, instead of this, the first to third magnetic sensors 30, 40, and 50 may each be constituted by a half-bridge circuit.

  In this case, instead of the first full-bridge circuits 31, 41, 51, as shown in FIG. 21A, the first half-bridge circuit is composed of anisotropic magnetoresistive elements 31a, 31b similar to those of the above-described embodiment. Configure. Then, power supply voltages + Vcc and -Vcc are applied to both ends of the anisotropic magnetoresistive elements 31a and 31b to extract voltage signals at the connection points of the anisotropic magnetoresistive elements 31a and 31b. Are supplied to the A / D converter 70 as the detection signals A0, A1, A2 of the above embodiment. Further, in place of the second full bridge circuits 32, 42, 52, as shown in FIG. 21B, the second half bridge circuit is configured by anisotropic magnetoresistive elements 32a, 32b similar to those of the above embodiment. To do. Then, power supply voltages + Vcc and -Vcc are applied to both ends of the anisotropic magnetoresistive effect elements 32a and 32b to extract a voltage signal at the connection point of the anisotropic magnetoresistive effect elements 32a and 32b. Are supplied to the A / D converter 70 as the detection signals B0, B1, and B2 of the above embodiment.

  Also in this case, when the first half bridge circuit and the second half bridge circuit are arranged to overlap at the same position, the two anisotropic magnetoresistive elements 31a and 31b of the first half bridge circuit are arranged. The first plane and the second plane on which the two anisotropic magnetoresistive elements 32a and 32b of the second half bridge circuit are arranged are parallel, and the two anisotropic magnetism of the first half bridge circuit The gravity center position C1 (middle point position) of the resistance elements 31a and 31b passes through the gravity center position C2 (middle point position) of the two anisotropic magnetoresistive elements 32a and 32b of the second half bridge circuit, and the second plane. It may be located on a straight line orthogonal to (and the first plane). Further, when the two anisotropic magnetoresistive elements 31a and 31b of the first half bridge circuit and the two anisotropic magnetoresistive elements 32a and 32b of the second half bridge circuit are arranged on the same plane. Is the center of gravity C1 of the two anisotropic magnetoresistive elements 31a and 31b of the first half bridge circuit and the center of gravity C2 of the two anisotropic magnetoresistive elements 32a and 32b of the second half bridge circuit. It is good to make it the same on the same plane.

  As described above, the first to third magnetic sensors 30, 40, 50 are configured by the first and second half bridges, respectively, so that the first to third magnetic sensors 30, 40, 50 are respectively the first and second half sensors. The first to third magnetic sensors 30, 40, and 50 can be easily configured, although the accuracy is lower than that of the two full-bridge circuits 31, 32, 41, 42, 51, and 52. In this case as well, there is a slight error if both the center of gravity positions C1 and C2 are shifted, but there is no practical problem as long as both center of gravity positions C1 and C2 are close. Further, even when the first to third magnetic sensors 30, 40, and 50 are configured by the first and second half bridges, respectively, instead of the anisotropic magnetoresistive elements 31a, 31b, 32a, and 32b, the above ( The artificial lattice type magnetoresistive element, metal-metal nanogranular magnetoresistive element or genus-insulator nanogranular magnetoresistive element of 1) to (3) may be used.

d4. Modified Examples of Arrangement of Bridge Circuits In the first to third magnetic sensors 30, 40, 50 of the above-described embodiment and modified examples, the first full bridge circuits 31, 41, 51 (or the first half bridge circuit) and the second The full bridge circuits 32, 42, 52 (or the second half bridge circuit) have different configurations (configurations that generate sine wave signals having a phase difference of 90 degrees), and the first full bridge circuits 31, 41, 51 (or the first The center-of-gravity positions C1, C2 of the half bridge circuit) and the second full bridge circuit 32, 42, 52 (or the second half bridge circuit) are set in the circumferential direction and the radial direction with respect to the rotation axes of the rotating magnets 21, 22. It was arranged at the same position. However, the first full bridge circuit 31, 41, 51 (or the first half bridge circuit) and the second full bridge circuit 32, 42, 52 (or the second half bridge circuit) have the same configuration, and the rotating magnet 21 , 22 may be arranged at positions separated by a quarter angle of one pole (position 90 degrees apart).

  For example, as shown in FIG. 22 corresponding to FIG. 3 described above, a full bridge circuit having the same configuration as the first full bridge circuit 31 described above is arranged at the position a as the first full bridge circuit 31 ′, and the above described A full bridge circuit having the same configuration as that of the first full bridge circuit 31 is arranged as the second full bridge circuit 31 ″ at the position b. Also by this, the output signals of the first and second full bridge circuits 31 ′ and 31 ″ are As the rotary magnets 21 and 22 rotate, they both change in a sine wave shape and have a 90-degree phase difference. As a result, this also makes it possible to detect the absolute rotation angle φ3 as in the case of the above embodiment and various modifications. Also in this case, the second full bridge circuit 32 described above may be used instead of the first and second full bridge circuits 31 ′ and 32 ″, or another full bridge circuit may be used. Instead of the full bridge circuit, a half bridge circuit may be used.

  However, the magnetization angle λ0 of the first magnetic pattern, the magnetization angle λ1 of the first block 22a of the second magnetic pattern, and the magnetization angle λ2 of the second block 22b of the second magnetic pattern are different, and λ1 <λ0 < There is a relationship of λ2. Therefore, as described above, when the first and second full bridge circuits 31 ′ and 31 ″ are arranged at positions separated by a quarter angle of one pole of the rotating magnets 21 and 22 (positions separated by 90 degrees), respectively. However, in this case, paying attention to the magnetization angle λ0, which is the angle between the magnetization angles λ1 and λ2, only the quarter angle of one pole of the first magnetic pattern is used. The first and second full bridge circuits 31 ′ and 32 ″ are arranged at positions separated (positions separated by 90 degrees). According to this, the phase difference between the sinusoidal detection signals A0 and B0 from the first magnetic sensor 30, the phase difference between the sinusoidal detection signals A1 and B1 from the second magnetic sensor 40, and the third magnetic sensor 50 The phase difference between the sinusoidal detection signals A2 and B2 is approximately 90 degrees. Therefore, errors in the detection signals A0, B0, A1, B1, A2, and B2 output from the first to third magnetic sensors 30, 40, and 50 can be reduced. In particular, if the respective differences λ0−λ1, λ2−λ0 between the magnetization angle λ0 of the first magnetic pattern and the magnetization angles λ1 and λ2 of the first and second blocks 22a and 22b of the second magnetic pattern are reduced. This error can be reduced.

d5. Variations of Arrangement of Rotating Magnets In the embodiment and various variations described above, the rotating magnets 21 and 22 are provided in two rows in the direction of the rotation axis, but the rotating magnets 21 and 22 are provided in two rows in the radial direction. It may be. 23A to 23C schematically show a rotation detection device according to this modification. 23 (a) is a plan view, FIG. 23 (b) is a side view, and FIG. 23 (c) is a bottom view. In FIG. 23 (c), the substrate 60 is omitted and the position thereof is indicated by a virtual line.

  In the rotation detection device, first and second rotating magnets 21A and 22A formed in an annular shape are fixed concentrically on the lower surface of a circular rotating plate 11 having a rotating shaft 10, and the first and first rotating magnets are fixed. Two rotating magnets 21 </ b> A and 22 </ b> A are projected below the rotating plate 11. The first and second rotating magnets 21A and 22A have the same first and second magnetic patterns as in the above embodiment. That is, the first magnetic pattern is a magnetization pattern in which N and S poles are alternately magnetized at equal intervals (magnetization angle λ0) over the entire circumference (360 degrees) in the circumferential direction. The second magnetic pattern is a first block 22a that is a magnetized pattern in which N and S poles are alternately magnetized at equal intervals (magnetization angle λ1) over a predetermined angle, and the predetermined angle from 360 degrees. This is a magnetization pattern comprising a second block 22b which is a magnetization pattern in which N and S poles are alternately magnetized at equal intervals (magnetization angle λ2) over the subtracted angle.

  In FIG. 23, the pole number n of the first magnetic pattern is “16”, the pole numbers n1 and n2 of the first and second blocks 22a and 22b are [9] and “7”, and the predetermined angle is 180 degrees. However, as described above, the number of poles n, n1, and n2 is equal to the number n of poles, and is equal to the added value n1 + n2 of the number of poles n1 and n2, and both the numbers of poles n1 and n2 are even. Or both may be odd numbers. If the sum of the angles of the first and second blocks 22a and 22b is 360 degrees, the angle of the first and second blocks 22a and 22b may not be 180 degrees. It should be noted that the relationship between the number of poles n, n1, and n2 and the magnetization angles λ0, λ1, and λ2 may be in the relationship of the above-described equations 10 and 11.

  In this case, the rotating magnets 21A and 22A magnetized with the first magnetic pattern and the second magnetic pattern may be provided separately in the radial direction, or may be configured to be bonded together. Further, the rotary magnets 21A and 22A may be configured by magnetizing the first magnetic pattern and the second magnetic pattern on an integral magnetic body.

  The rotation detection device according to this modification also includes first to third magnetic sensors 30A, 40A, and 50A. The 1st thru | or 3rd magnetic sensors 30A, 40A, 50A are comprised similarly to the case of the said embodiment or its modification. The first magnetic sensor 30A is fixed to the upper surface of the substrate 60 so that the rotation axis of the rotating magnet 21A is orthogonal to the magnetic sensitive surface, and is positioned at an intermediate position in the vertical direction of the rotating magnet 21A (first magnetic pattern). And it is arrange | positioned at the radial inside of the rotating magnet 21A. The second and third magnetic sensors 40 and 50 are fixed to the upper surface of the substrate 60 so that the rotation axis of the rotating magnet 22A is orthogonal to the magnetic sensing surface, and the upper and lower surfaces of the rotating magnet 22A (second magnetic pattern) are fixed. It is arranged on the radially outer side of the rotating magnet 22A at an intermediate position in the direction. On the upper surface of the substrate 60, support portions 60a, 60b, and 60c that support the first to third magnetic sensors 30A, 40A, and 50A are integrally provided.

  The radial distance from the center position (center of gravity position) of the first magnetic sensor 30A to the inner surface of the rotating magnet 21A, and from the center position (center of gravity position) of the second and third magnetic sensors 40A, 50A to the outer surface of the rotating magnet 22A. All radial distances are the same. Also in this case, the circumferential positions of the second and third magnetic sensors 40A and 50A are different from each other by 90 degrees around the rotation axis of the rotating magnets 21A and 22A, and the circumferential position of the first magnetic sensor 30A is the rotating magnet. Although it may be any position around the rotation axis of 21A and 22A, in order to reduce the area of the substrate 60, it may be between the second and third magnetic sensors 40A and 50A in the circumferential direction. The substrate 60 extends in a radial direction from a position slightly inside the inner surface of the rotating magnet 21A to an outer position from the outer surface of the rotating magnet 22A, and extends in the circumferential direction by an angle slightly larger than 90 degrees. And is fixed to a member (not shown). The point that the above-described electric circuit is disposed on the substrate 60 is the same as that in the above embodiment.

  Other configurations are the same as those of the above-described embodiment and its modification, and the rotation detection device according to this modification also operates in the same manner as the above-described embodiment and its modification. Therefore, also with the rotation detection device according to this modification, the same functional effect as that of the above embodiment and the modification is expected.

  In this modification, the rotating magnets 21A and 22A are formed in an annular shape, and are arranged in two rows in the radial direction at positions that coincide with each other in the rotating shaft direction of the rotating magnets 21A and 22A. A plate-like substrate 60 extending in the circumferential direction is disposed at a position away from the lower surface of the substrate so as to face the lower surface, and the first to third magnetic sensors 30A, 40A, and 50A are disposed on the substrate 60. Fixed to the upper surface, the first magnetic sensor 30A is opposed to the first magnetic pattern of the rotating magnet 21A, and the second and third magnetic sensors 30A, 40A are opposed to the second magnetic pattern of the rotating magnet 22A. . Therefore, also in this modification, the first to third magnetic sensors 30A, 40A, and 50A can be mounted on one substrate 60, so that the structure of the rotation detection device is simplified. Further, in this modification as well, the first magnetic sensor 30A is disposed between the second and third magnetic sensors 40A and 50A in the circumferential direction of the rotating magnets 21A and 22A. The first to third magnetic sensors 30A, 40A, and 50A can be mounted on the substrate 60 by making the extension angle slightly larger than 90 degrees, and the substrate 60 can be reduced in size.

d6. Modified Example of Arrangement of Magnetic Sensor In the embodiment and the modified example thereof, the first magnetic sensor 30 is fixed to the upper surface of the substrate 60, and the second and third magnetic sensors 40, 50 are fixed to the lower surface of the substrate 60. However, instead of this, the substrate 60 may be provided below the rotary magnets 21, 22, and all of the first to third magnetic sensors 30, 40, 50 may be fixed to the upper surface of the substrate 60. Further, the substrate 60 may be provided above the rotary magnets 21 and 22 so that all of the first to third magnetic sensors 30, 40 and 50 are fixed to the lower surface of the substrate 60. In this case, the support portions 60a, 60b, and 60c as described in the modified example of d5 may be provided on the upper surface or the lower surface of the substrate 60. In this case, the axial position, radial position, and circumferential position of the first to third magnetic sensors 30, 40, 50 with respect to the rotating shaft 10 are the same as those in the above embodiment.

  Further, if the rotary magnets 21 and 22 are formed in an annular shape, the first and second magnetic patterns of the rotary magnets 21 and 22 are parallel to the rotary magnets 21 and 22 so that the rotation axes of the rotary magnets 21 and 22 are orthogonal to each other. A magnetic field is generated in a smooth plane. In this case, the rotating magnets 21 and 22 are fixed to the upper or lower surface of the rotating plate 11 that rotates integrally with the rotating shaft 10 as described in the modified example of d5. When the rotary magnets 21 and 22 are formed in an annular shape as described above, a part or all of the first to third magnetic sensors 30, 40 and 50 are arranged inside the rotary magnets 21 and 22. May be. In this case, the axial position and the circumferential position of the first to third magnetic sensors 30, 40, 50 with respect to the rotating shaft 10 are the same as those in the above embodiment, and the first to third magnetic sensors 30, 40, The radial position with respect to a part or all of the rotation shafts 50 is set inside the rotary magnets 21 and 22.

  Furthermore, in the above-described embodiment and the modification thereof, the first to third magnetic sensors 30, 40, and 50 have the rotational axes of the rotary magnets 21 and 22 and the magnetic sensitive surfaces of the first to third magnetic sensors 30, 40, and 50. It arrange | positioned on the outer side or inner side of the side surface of the rotating magnets 21 and 22 so that it might orthogonally cross with respect to. However, the first and second magnetic patterns of the rotating magnets 21 and 22 generate a magnetic field on the upper surface side and the lower surface side of the rotating magnets 21 and 22 in a plane parallel to the rotation axis of the rotating magnets 21 and 22. Therefore, as shown in the top view of FIG. 24 (a), the first magnetic sensor 30 is placed on the upper side of the upper surface of the rotating magnets 21, 22 so that the magnetic sensitive surface is parallel to the tangential direction of the rotating magnets 21, 22. You may make it arrange | position to. Further, as shown in the bottom view of FIG. 24B, the second and second magnetic sensors 40 and 50 are arranged so that the magnetosensitive surfaces are parallel to the tangential direction of the rotary magnets 21 and 22. You may make it arrange | position below the lower surface of 22. Also in this case, the positional relationship between the radial direction and the circumferential direction of the first to third magnetic sensors 30, 40, 50 is the same as that of the first embodiment and the modification thereof. This also makes it possible to detect the absolute rotation angle φ3.

  In the modified example of d5, the first magnetic sensor 30A is provided inside the rotating magnet 21A, and the second and third magnetic sensors 40A, 50A are provided outside the rotating magnet 22A. However, if the magnetization pattern of the rotary magnet 21A and the magnetization pattern of the rotary magnet 22A are interchanged, the first magnetic sensor 30A is provided outside the rotary magnet 22A, and the second and third magnetic sensors 40A, 50A are provided as the rotary magnet 21A. You may make it provide inside. In this case, the axial position and the circumferential position of the first to third magnetic sensors 30A, 40A, 50A with respect to the rotating shaft 10 are the same as in the modified example of d5.

  Further, if a gap is provided between the rotating magnets 21A and 22A and a magnetic shielding member is provided in the modified example of d5, or the radial gap between the rotating magnets 21A and 22A is sufficiently increased, the rotating magnets 21A and 22A are On both the inner and outer sides of the rotating magnets 21A and 22A, magnetic fields are generated in parallel planes where the rotating shafts 10 of the rotating magnets 21A and 22A are orthogonal to each other. Therefore, in this case, the first magnetic sensor 30A may be provided outside the rotating magnet 21A, or the second and / or third magnetic sensors 40A, 50A may be provided inside the rotating magnet 22A. In this case as well, the axial position and the circumferential position of the first to third magnetic sensors 30A, 40A, 50A with respect to the rotating shaft 10 are the same as in the modified example of d5.

  Further, as described above, the radial interval between the rotating magnets 21A and 22A is sufficiently large, and the first magnetic sensor 21A is disposed outside the rotating magnet 21A, or between the rotating magnets 21A and 22A or the rotating magnet. When the second and second magnetic sensors 30A and 30B are arranged outside 22A, the rotating magnet 21A may be formed in a circular shape instead of an annular shape. To summarize these modifications, the first magnetic pattern is formed on the rotating magnet 21A, the second magnetic pattern is formed on the rotating magnet 22A, the rotating magnet 21A is formed in a circular shape or an annular shape, and the rotating magnet 22A is formed. The rotary magnet 21A is formed in an annular shape having an inner diameter larger than the outer diameter, and the rotary magnets 21A and 22A are arranged in two rows in the radial direction with the same rotary shaft at the same position in the rotary shaft direction. The first magnetic sensor 30A is disposed opposite the outer peripheral surface of the first magnetic pattern of the rotating magnet 21A or the inner peripheral surface of the first magnetic pattern, and the second and third magnetic sensors 40A, 50A. May be arranged to face the outside of the outer peripheral surface of the second magnetic pattern of the rotating magnet 22A or the inner side of the inner peripheral surface of the second magnetic pattern. Further, the second magnetic pattern is formed on the rotating magnet 21A, the first magnetic pattern is formed on the rotating magnet 22A, and the second and third magnetic sensors 40A and 50A are arranged on the outer peripheral surface of the second magnetic pattern of the rotating magnet 21A. The first magnetic sensor 30A is arranged on the outer side or on the inner side of the inner peripheral surface of the second magnetic pattern, and the first magnetic sensor 30A is disposed on the outer side of the outer peripheral surface of the first magnetic pattern of the rotating magnet 22A or You may make it arrange | position facing an inner side.

  Further, also in the modified example of d5, the first to third magnetic sensors 30A, 40A, 50A are arranged so that the rotating magnets 21 and 22 are arranged so that the rotational axes of the rotating magnets 21A and 22A are orthogonal to the magnetic sensitive surface. Arranged inside and outside the side. However, also in this case, the rotating magnets 21A and 22A (first and second magnetic patterns) generate a magnetic field in a plane parallel to the rotation axis of the rotating magnets 21 and 22 also on the lower surface side of the rotating magnets 21 and 22. Occur. Therefore, as shown in the bottom view of FIG. 25, the first magnetic sensor 30A is placed under the lower surface of the rotating magnet 21A so that the magnetic sensitive surface is parallel to the tangential direction of the rotating magnet 21A (first magnetic pattern). You may make it arrange | position to. Further, the second and second magnetic sensors 40A and 50A are arranged below the lower surface of the rotating magnet 22A so that the magnetosensitive surface is parallel to the tangential direction of the rotating magnet 22A (second magnetic pattern). May be. Also in this case, the positional relationship in the radial direction and the circumferential direction of the first to third magnetic sensors 30A, 40A, 50A is the same as in the case of the first embodiment and its modification. Also by these various modifications, the absolute rotation angle φ3 can be detected.

d7. Other Modifications Furthermore, in the above-described embodiment and various modifications, the rotation detection device according to the present invention has been described with respect to the rotation detection device. However, naturally, the rotation detection device according to the present invention has a rotation shaft. The present invention is also applied to a rotation detection device that does not pass through.

DESCRIPTION OF SYMBOLS 10 ... Rotating shaft, 11 ... Rotating plate, 21, 22, 21A, 22A ... Rotating magnet, 30, 30A ... 1st magnetic sensor, 40, 40A ... 2nd magnetic sensor, 50, 50A ... 3rd magnetic sensor, 31, 41, 51 ... first full bridge circuit, 32, 42, 52 ... second full bridge circuit, 33, 34, 43, 44, 53, 54 ... differential amplifier, 60 ... substrate, 70 ... A / D converter, 80. Signal processing circuit

Claims (13)

A first magnetic pattern formed in a circular shape or in an annular shape and having N poles and S poles arranged alternately along the circumferential direction, and is attached to a rotating body and rotates according to the rotation of the rotating body; One rotating magnet,
A second magnetic pattern formed in a circular shape or in an annular shape and having N and S poles arranged alternately along a circumferential direction, and is attached to the rotating body, and the second magnetic pattern is rotated according to the rotation of the rotating body; A second rotating magnet that rotates about a rotation axis common to the one rotating magnet;
The first magnetic pattern is disposed opposite to the first magnetic pattern, detects a change in the magnetic field due to the first magnetic pattern, and outputs two detection signals having different phases of one cycle per pole of the first magnetic pattern. A magnetic sensor;
The second magnetic pattern is disposed opposite to the second magnetic pattern, detects a change in the magnetic field due to the second magnetic pattern, and outputs two detection signals having different phases of one cycle per pole of the second magnetic pattern. A magnetic sensor;
The second magnetic pattern is opposed to the second magnetic sensor and is disposed 90 degrees away from the second magnetic sensor in the circumferential direction of the second rotating magnet. A rotation detection device comprising: a third magnetic sensor that outputs two detection signals having different phases in one cycle per pole of a magnetic pattern;
The first magnetic pattern is evenly magnetized alternately with N and S poles at a first magnetization angle, and has an even number of poles;
The second magnetic pattern includes a first block that is evenly magnetized alternately at N and S poles at a second magnetization angle smaller than the first magnetization angle, and a third block that is larger than the first magnetization angle. A second block that is magnetized alternately at N and S poles evenly at a magnetization angle;
The sum of the number of poles of the first block and the number of poles of the second block is set equal to the number of poles of the first magnetic pattern;
The first to third magnetization angles are λ0, λ1, and λ2, respectively, the number of poles of the one magnetic pattern and the total number of poles of the first and second blocks of the second magnetic pattern are each n, If the difference between the number of poles in one block and the number of poles in the second block is 2 · a,
(n + 2a-2) / (n + 2 · a) ≦ λ1 / λ0 <1 and 1 <λ2 / λ0 ≦ (n-2 · a + 2) / (n-2 · a)
Rotation detector that satisfies the inequality of   The two detection signals output by the first magnetic sensor are sinusoidal signals that are 90 degrees or approximately 90 degrees out of phase, and the two detection signals output by the second magnetic sensor are 90 degrees or approximately the phase. 2. The rotation detection device according to claim 1, wherein the two detection signals output by the third magnetic sensor are sinusoidal signals having phases different by 90 degrees or almost 90 degrees, which are sinusoidal signals different by 90 degrees.   Furthermore, the two detection signals output by the first magnetic sensor, the two detection signals output by the second magnetic sensor, and the two detection signals output by the third magnetic sensor are input, The rotation detection device according to claim 1, further comprising a signal processing circuit that calculates a rotation angle of the rotating body using an input detection signal. The signal processing circuit includes:
Two detection signals output from the first magnetic sensor are subjected to arc tangent to calculate a first arc tangent value, and two detection signals output from the second magnetic sensor are subjected to arc tangent to calculate a second inverse tangent. Arc tangent calculation processing for calculating a tangent value and calculating a third arc tangent value by calculating an arc tangent of two detection signals output by the third magnetic sensor;
The phase difference between the first arc tangent value and the second arc tangent value is calculated as the first phase difference value, and the phase difference between the first arc tangent value and the second arc tangent value is calculated as the second phase difference. Phase difference calculation processing to calculate as a value;
The rotation detection device according to claim 3, wherein a rotation angle deriving calculation process for deriving a rotation angle of the rotating body using the first phase difference value and the second phase difference value is performed.   The rotation detection device according to claim 4, wherein the signal processing circuit further performs an interpolation calculation process of the derived rotation angle using the calculated first arc tangent value.   The rotation detection device according to claim 1, wherein a difference between the number of poles of the one block and the number of poles of the second block is “2”. The first magnetic sensor to the third magnetic sensor are bridged with a first bridge circuit in which a plurality of magnetoresistive elements extending in the same plane are bridge-connected, and a plurality of magnetoresistive elements extended in the same plane. Each consists of a connected second bridge circuit,
Magnetic sensing surfaces of a plurality of magnetoresistive elements that respectively constitute the first bridge circuit and the second bridge circuit of the first magnetic sensor are arranged in a plane along which magnetic lines of force due to the first magnetic pattern travel, and the second magnetic sensor Magnetic sensing surfaces of a plurality of magnetoresistive elements respectively constituting the first bridge circuit and the second bridge circuit are arranged in a plane along which magnetic lines of force due to the second magnetic pattern travel, and the first bridge circuit of the third magnetic sensor, 7. The magnetic sensing surfaces of a plurality of magnetoresistive elements that respectively constitute the second bridge circuit are arranged in a plane along which a magnetic force line by the second magnetic pattern travels. Rotation detection device.   The extending direction of the plurality of magnetoresistive elements constituting the first bridge circuit is different from the extending direction of the plurality of magnetoresistive elements constituting the second bridge circuit by 45 degrees, respectively. 7. A rotation detection device according to 7. In each of the first to third magnetic sensors,
Arranging a plurality of magnetoresistive elements constituting the first bridge circuit and a plurality of magnetoresistive elements constituting the second bridge circuit,
The plurality of magnetoresistive elements constituting the first bridge circuit pass through the center of gravity of the plurality of magnetoresistive elements constituting the second bridge circuit, and the plurality of magnetoresistive elements constituting the first bridge circuit. The rotation detection device according to claim 7 or 8, wherein the rotation detection device is positioned on a straight line orthogonal to a plane in which the elements are arranged. In each of the first to third magnetic sensors,
A plurality of magnetoresistive elements constituting the first bridge circuit and a plurality of magnetoresistive elements constituting the second bridge circuit are arranged in the same plane;
The rotation according to claim 7 or 8, wherein the gravity center positions of the plurality of magnetoresistive elements constituting the first bridge circuit and the gravity center positions of the plurality of magnetoresistive elements constituting the second bridge circuit are made to coincide with each other. Detection device. The first rotating magnet and the second rotating magnet are arranged in two rows in the rotation axis direction and have the same outer diameter or inner diameter,
Outside the outer peripheral surfaces of the first and second rotating magnets having the same outer diameter or inside the inner peripheral surfaces of the first and second rotating magnets having the same inner diameter, the first rotating magnet and the A plate-like substrate extending in the circumferential direction is arranged at the boundary position of the second rotating magnet,
The first magnetic sensor is fixed to one surface of the substrate and is opposed to the first magnetic pattern, and the second and third magnetic sensors are fixed to the other surface of the substrate and the second magnetic pattern is fixed. The rotation detection device according to any one of claims 1 to 10, wherein the rotation detection device is opposed to the rotation detection device. One of the first rotating magnet and the second rotating magnet is formed in a circular or annular shape, and the other rotating magnet of the first rotating magnet and the second rotating magnet is the one rotating magnet. It is formed in an annular shape having an inner diameter larger than the outer diameter of the rotating magnet, and the first and second second rotating magnets have the same rotating shaft in two rows in the radial direction at the same position in the rotating shaft direction. Arranged,
A plate-like substrate extending in the circumferential direction is arranged at a position away from one surface in the rotation axis direction of the first and second rotating magnets so as to face the one surface,
The first to third magnetic sensors are fixed to the surface of the substrate facing the first and second rotating magnets, the first magnetic sensor is opposed to the first magnetic pattern, and the second and second magnetic sensors are fixed. The rotation detection device according to any one of claims 1 to 10, wherein three magnetic sensors are arranged to face the second magnetic pattern.   The rotation detection device according to claim 10 or 11, wherein the first magnetic sensor is disposed between the second magnetic sensor and the third magnetic sensor in a circumferential direction of the first and second rotating magnets. .

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