JP5762567B2 - Rotation angle detector - Google Patents

Description

  The present invention relates to a rotation angle detection device that detects a rotation angle of a rotation shaft or the like using a magnetoresistive effect element.

As magnetic-electric conversion element that detect the magnetic field applied from the outside, the magnetoresistive elements are known in addition to the Hall element. The magnetoresistive elements include AMR (Anisotropic Magneto-Resistance) elements, GMR (Giant Magneto-Resistance) elements, and TMR (Tunnel Magneto-Resistance) elements. There are elements. In particular, GMR elements and TMR elements that can obtain a larger MR ratio than others are drawing attention.

  Patent Document 1 discloses a GMR element and a TMR element having a spin valve structure. In general, a magnetoresistive effect element having a spin valve structure includes a ferromagnetic first thin film layer (free layer) and a second thin film layer (fixed layer) which are partitioned by a nonmagnetic thin film layer. The magnetization direction of the ferromagnetic second thin film layer is fixed. In order to fix the magnetization direction of the second thin film layer, an antiferromagnetic thin film layer is attached to the ferromagnetic second thin film layer. As an alternative structure, the antiferromagnetic thin film layer may be a ferromagnetic layer having high coercivity and high electrical resistance.

  Next, the principle of operation of the rotation angle detector using a magnetoresistive element having a spin valve structure will be described. A magnet rotor equipped with a cylindrical magnet whose peripheral surface is multipolarized is rotated about an axis. When detecting the rotation angle of the magnet rotor using the magnetoresistive effect element, as shown in FIG. 37, the sensor device is arranged at a position away from the peripheral surface of the cylindrical magnet by a predetermined distance r. Regions A and B are provided in the sensor device at the same interval as the magnetization width λ of the cylindrical magnet, the magnetoresistive elements RA1 and RA2 are arranged in the region A, and the magnetoresistive elements RB1 and RB2 are arranged in the region B. As shown in FIG. 38, RA1, RA2, RB1, and RB2 are connected to form a bridge circuit.

  In FIG. 37, the cylindrical magnet on the circumferential surface of the magnet rotor is schematically described in a straight line. When the magnet rotor rotates in this state, the circumferential surface of the magnet rotor moves in the direction of the arrow with respect to the sensor device.

  Here, the phase angle θ shown in FIG. 37 indicates the phase relationship between the region A and the magnetic poles of the magnet rotor 1. The phase angle θ coincides with the angle of the magnetic field in the region A. Further, the phase angle θ ′ shown in FIG. 40 indicates the angle of the magnetic field in the region B when the phase relationship between the region A and the magnetic pole of the magnet rotor 1 is θ.

  With the movement of the magnet rotor, the polarity of the peripheral surface of the magnet rotor facing the magnetoresistive effect elements RA1 and RA2 changes from the N pole ((a) θ = 0 °) to the boundary between the N pole and the S pole ( (B) θ = 90 °), S pole ((c) θ = 180 °), boundary between S pole and N pole ((d) θ = 270 °), N pole ((e) θ = 360 °) And change. Therefore, as shown in FIG. 39, the angle θ of the magnetic field sensed by the magnetoresistive elements RA1 and RA2 arranged in the region A changes from 0 ° to 360 °. Similarly, the angle of the magnetic field sensed by the magnetoresistive effect elements RB1 and RB2 arranged in the region B changes as shown in FIG.

  In a magnetoresistive element having a spin valve structure, the resistance value changes in accordance with the angle of the magnetic field applied to the element. As shown in FIG. 41, the resistance values of the magnetoresistive effect elements RA1, RA2 and RB1, RB2 change substantially sinusoidally with the rotation of the magnet rotor. Therefore, the midpoint potentials V1 and V2 and the bridge output Vout of the bridge circuit shown in FIG. 38 have waveforms as shown in FIG.

  FIG. 43 is an explanatory diagram showing in detail the angle of the magnetic field of the conventional rotation angle detection device. Normally, the magnetic fields generated by the magnet rotor in the radial direction (x-axis direction in FIG. 43) and in the rotation direction (y-axis direction in FIG. 43) change substantially sinusoidally with respect to the phase angle. However, as shown in FIG. 43, the magnetic field amplitude differs between the rotational direction and the radial direction. The amplitude P of the magnetic field in the radial direction is generally 1 to 2 times the amplitude Q of the magnetic field in the rotation direction. Therefore, the x-axis component Hx and the y-axis component Hy of the magnetic field at the phase angle θ can be expressed by the following equations (1) and (2). Therefore, tan α representing the direction of the magnetic field at the phase angle θ and the direction α of the magnetic field can be represented by the following equations (3) and (4), respectively.

  FIG. 44 shows the relationship between the phase angle θ and the magnetic field angle α sensed by the magnetoresistive effect element in the conventional rotation angle detection device when the ratio of the amplitudes of the magnetic field magnitudes in the radial direction and the rotation direction is different. FIG. Usually, as described above, Q / P = 1 to 0.5. As shown in FIG. 44, when Q / P = 1, that is, when the amplitude of the magnitude of the magnetic field in the rotation direction and the radial direction is equal, θ = α. On the other hand, when the amplitude of the magnitude of the magnetic field in the radial direction is larger than the amplitude of the magnitude of the magnetic field in the rotation direction, for example, when Q / P = 0.7 or Q / P = 0.5, it is shown in FIG. It becomes such a relationship. Therefore, as the magnet rotor rotates, the resistance value of each magnetoresistive element changes in a triangular wave shape as shown in FIG.

  46 and 47 are waveform diagrams showing changes in the output voltage of the conventional rotation angle detecting device when the ratio of the amplitudes of the magnetic field magnitudes in the radial direction and the rotation direction is different. As shown in FIG. 45, when the resistance value of the magnetoresistive element has a triangular waveform, a third-order harmonic component is added to the output voltage Vout of the bridge circuit, and the output waveform is distorted. The influence of the fifth and higher harmonics is small, and the third harmonic component is the main cause of distortion. If the output waveform is distorted and becomes a triangular wave as shown in FIG. 46 or a trapezoidal wave as shown in FIG. 47, accurate angle information cannot be obtained.

  In Patent Document 2, analog-digital (A-D) conversion is performed on the detected magnetic field magnitudes in the radial direction and the rotation direction to obtain Vx signals and Vy signals, respectively, so that the respective amplitudes are the same. A rotation angle detection device is disclosed that can detect a rotation angle without distortion by multiplying a rotation direction detection signal by a correction coefficient k.

Japanese Examined Patent Publication No. 8-21166 International Publication No. 2009/099054 JP 63-279101 A JP-A-2-24512 JP-A-2-194316 JP 2009-210550 A

  As described above, when rotating a magnet rotor equipped with a cylindrical magnet whose peripheral surface is magnetized with multiple poles around the axis and detecting the rotation angle, the magnitude of the magnetic field in the radial direction and the rotational direction is large. If the amplitudes are different, distortion caused mainly by the third harmonic component is applied to the detected output waveform. Therefore, accurate angle information cannot be obtained. If the rotation angle detection device according to Patent Document 2 is used, the amplitudes of the magnetic field magnitudes in the radial direction and the rotation direction are the same, the third harmonic component applied to the detection output waveform is suppressed, and accurate angle information is obtained. It will be obtained. However, in order to obtain this rotation angle detection device, an A / D converter, a circuit for calculating the coefficient k, and a multiplier for multiplying the coefficient k are required, so that the circuit scale increases.

  An object of the present invention is to provide a rotation angle detection device capable of obtaining accurate angle information while reducing the circuit scale.

In order to achieve the above object, one aspect of the present invention is a rotation angle detection device, in which a north pole and a south pole are alternately magnetized along a circumferential surface with a magnetization width λ, First to eighth magnetic detectors for sensing the magnetic field generated by the rotating body, the first magnetic detector and the fourth magnetic detector are disposed at the first detection position, the second magnetic detector and the third magnetic detector The magnetic detection unit is disposed at the second detection position, the fifth magnetic detection unit and the eighth magnetic detection unit are disposed at the third detection position, and the sixth magnetic detection unit and the seventh magnetic detection unit are the fourth detection. It is disposed at a position, the first detection position and the second detection position provided apart distance L _12, and the third detection position and a fourth detection position provided apart distance L _12, the first detection position and the third detecting position and provided apart distance L ₁₃ is between the first reference potential and second reference potential, a first magnetic detection connected in series The third magnetic detection unit and the second magnetic detection unit and the fourth magnetic detection unit connected in series are connected in parallel, and the first to fourth magnetic detection units constitute a bridge circuit, and the first magnetic detection unit And the fourth magnetic detection unit, the second magnetic detection unit, and the third magnetic detection unit are arranged on the arms where the bridge circuit intersects, and are connected in series between the third reference potential and the fourth reference potential. A fifth magnetic detection unit and a seventh magnetic detection unit, and a sixth magnetic detection unit and an eighth magnetic detection unit connected in series are arranged, and the fifth to eighth magnetic detection units constitute a bridge circuit, and The 5th magnetic detection unit and the 8th magnetic detection unit, the 6th magnetic detection unit and the 7th magnetic detection unit are respectively arranged on the arms where the bridge circuit intersects, and the midpoint between the first magnetic detection unit and the third magnetic detection unit the difference _{V 12} between the potential _{V 1,} and the second magnetic detection portion and the midpoint potential _{V 2} of the fourth magnetic detection unit ( V ₂ -V ₁₎ and a fifth magnetic detection portion and the seventh midpoint potential _{V 3} of the magnetic detector, the sixth magnetic detection unit and the difference _{V 34} between the middle point potential _{V 4} of the 8 magnetic detection unit ( = V ₄ −V ₃ ) Based on the difference Vout (= V ₃₄ −V ₁₂ ), a signal corresponding to the rotation angle of the rotating body is output, and L ₁₂ = 2λ / n ₁ (n ₁ is 2 or more) Integer), L ₁₃ = 2λ / n ₂ (n ₂ is an integer of 2 or more).

Another embodiment of the present invention is a rotation angle detection device, in which a north pole and a south pole are alternately magnetized along a circumferential surface with a magnetization width λ, and a magnetic field generated by the rotor 2 ^{p + 1} (p is an integer greater than or equal to 2 ) magnetic detection units, and two magnetic detection units are arranged at each of 2 ^p detection positions, i-th detection position (i is 1 or more) The distance between the first detection potential and the jth detection position (j is an integer equal to or greater than 1) is L _ij , and 2 ^p pieces connected in series between the first reference potential and the second reference potential a magnetic detection unit, and 2 ^p pieces of the magnetic detector connected in series are connected in parallel, 2 p ^{+ 1} pieces of magnetic detection unit constitute a bridge circuit, each arm of the bridge circuit, 2 ^p-1 or arranged magnetic detection portion of each of the first arm and the fourth arm is arranged at the intersection of the bridge circuit, the second The arm and the third arm are arranged at the position where the bridge circuit intersects, and the magnetic detection unit arranged at the same detection position is arranged at the arm where the bridge circuit intersects, and the midpoint of the first arm and the third arm Based on the difference Vout (= V ₂ −V ₁ ) between the potential V ₁ and the midpoint potential V _{2 of} the second arm and the fourth arm, a signal corresponding to the rotation angle of the rotating body is output, and L _ij = 2λ / n _{k (ij)} (n _{k (ij)} is an integer of 2 or more ₎ is satisfied.

According to the present invention, based on Vout obtained from a plurality of magnetic detection units constituting a bridge circuit, it corresponds to a rotation angle of a rotating body in which two or more types of harmonic components including external noise are suppressed. Signal is output. As a result, accurate angle information of the rotating body can be obtained.

It is a block diagram of the rotation angle detection apparatus of this invention. FIG. 3 is a layout diagram of regions provided in the sensor device according to the first embodiment of the present invention. It is a wiring diagram of the magnetoresistive effect element in the rotation angle detection apparatus by Embodiment 1 of this invention. It is a wave form diagram which shows the change of the resistance value of a magnetoresistive effect element of the rotation angle detection apparatus by Embodiment 1 of this invention. It is a wave form diagram which shows the change of the output electric potential of the rotation angle detection apparatus by Embodiment 1 of this invention about the case where the arrangement space | interval of a magnetoresistive effect element differs. FIG. 6 is a waveform diagram showing a difference between the output potential of FIG. 5 and a sine wave whose DC component, amplitude, frequency, and phase are adjusted. It is a wave form diagram which shows the resistance value of a magnetoresistive effect element, and the change of an output potential when the 5th-order harmonic component of the rotation angle detection apparatus by Embodiment 1 of this invention is added. It is a wave form diagram which shows the change of the output potential when the 5th-order harmonic component is added of the rotation angle detection apparatus according to Embodiment 1 of the present invention when the arrangement intervals of the magnetoresistive effect elements are different. FIG. 9 is a waveform diagram showing a difference between the output potential of FIG. 8 and a sine wave whose DC component, amplitude, frequency, and phase are adjusted. It is a wiring diagram of the magnetoresistive effect element in the rotation angle detection apparatus by Embodiment 2 of this invention. It is a wave form diagram which shows the change of the resistance value of a magnetoresistive effect element, and a midpoint potential of the rotation angle detection apparatus by Embodiment 2 of this invention. It is a wave form diagram which shows the change of the output voltage of the rotation angle detection apparatus by Embodiment 2 of this invention about the case where the arrangement intervals of a magnetoresistive effect element differ. FIG. 13 is a waveform diagram showing a difference between the output voltage of FIG. 12 and a sine wave whose DC component, amplitude, frequency, and phase are adjusted. It is a wave form diagram which shows the change of the resistance value of a magnetoresistive effect element, and a midpoint potential when the 5th-order harmonic component of the rotation angle detection apparatus by Embodiment 2 of this invention is added. It is a wave form diagram which shows the change of the output voltage when the 5th-order harmonic component is added of the rotation angle detection apparatus by Embodiment 2 of this invention about the case where arrangement intervals of a magnetoresistive effect element differ. It is a wave form diagram which shows the difference of the output voltage of FIG. 15, and the sine wave which adjusted the direct current | flow component, the amplitude, the frequency, and the phase. It is a wiring diagram of the magnetoresistive effect element in the rotation angle detection apparatus by Embodiment 3 of this invention. It is a layout drawing of the area | region provided in the sensor device of the rotation angle detection apparatus by Embodiment 3 of this invention. FIG. 19 is a waveform diagram showing changes in the resistance value, midpoint potential, and differential voltage of the magnetoresistive effect element included in the bridge circuit A in the rotation angle detection device according to the third embodiment of the present invention with respect to the arrangement in FIG. 18. FIG. 19 is a waveform diagram showing changes in the resistance value, midpoint potential, and differential voltage of the magnetoresistive effect element included in the bridge circuit B of the rotation angle detection device according to the third embodiment of the present invention with respect to the arrangement in FIG. 18. It is a wave form diagram which shows the change of a differential voltage and an output voltage of the rotation angle detection apparatus by Embodiment 3 of this invention about the arrangement | positioning of FIG. It is a wave form diagram which shows the difference of the differential voltage and output voltage of FIG. 21, and the sine wave which adjusted the direct current | flow component, the amplitude, the frequency, and the phase. It is an alternative figure of arrangement | positioning of the area | region provided in the sensor device of the rotation angle detection apparatus by Embodiment 3 of this invention. It is an alternative figure of arrangement | positioning of the area | region provided in the sensor device of the rotation angle detection apparatus by Embodiment 3 of this invention. FIG. 25 is a waveform diagram showing changes in the resistance value, midpoint potential, and differential voltage of the magnetoresistive effect element included in the bridge circuit A in the rotation angle detection device according to the third embodiment of the present invention with respect to the arrangement of FIG. FIG. 25 is a waveform diagram showing changes in the resistance value, midpoint potential, and differential voltage of the magnetoresistive effect element included in the bridge circuit B of the rotation angle detection device according to the third embodiment of the present invention with respect to the arrangement of FIG. Of the rotation angle detection apparatus according to a third embodiment of the present invention, the change in the differential voltage and the output voltage is a waveform diagram showing the arrangement of Figure 24. It is a wave form diagram which shows the difference of the differential voltage and output voltage of FIG. 27, and the sine wave which adjusted DC component, an amplitude, a frequency, and a phase. It is an alternative figure of arrangement | positioning of the area | region provided in the sensor device of the rotation angle detection apparatus by Embodiment 3 of this invention. It is a wiring diagram of the magnetoresistive effect element in the rotation angle detection apparatus by Embodiment 4 of this invention. It is a wave form diagram which shows the resistance value of a magnetoresistive effect element, and the change of a midpoint potential of the rotation angle detection apparatus by Embodiment 4 of this invention. FIG. 32 is a waveform diagram showing the midpoint potential of FIG. 31 and the difference between the output voltage and a sine wave whose DC component, amplitude, frequency and phase are adjusted. It is an alternative figure of arrangement | positioning of the area | region provided in the sensor device of the rotation angle detection apparatus by Embodiment 4 of this invention. It is a wiring diagram of the magnetoresistive effect element in the rotation angle detection apparatus by Embodiment 4 of this invention. It is a table | surface which shows the example of the arrangement | positioning space | interval of each area | region and wiring of each magnetoresistive effect element which can suppress p types of harmonic components of the rotation angle detection apparatus by Embodiment 4 of this invention. It is an alternative figure of the structure of the rotation angle detection apparatus of this invention. It is the layout of the area | region provided in the sensor device by the conventional rotation angle detection apparatus. It is a wiring diagram of a magnetoresistive effect element in the conventional rotation angle detection apparatus. It is explanatory drawing which shows the angle of the magnetic field in the area | region A of the conventional rotation angle detection apparatus. It is explanatory drawing which shows the angle of the magnetic field in the area | region B of the conventional rotation angle detection apparatus. It is a wave form diagram which shows the change of the resistance value of a magnetoresistive effect element of the conventional rotation angle detection apparatus. It is a wave form diagram which shows the change of the middle point electric potential and output voltage of the conventional rotation angle detection apparatus. It is explanatory drawing which shows the angle of the magnetic field of the conventional rotation angle detection apparatus in detail. It is a figure which shows the relationship between phase angle (theta) and the angle (alpha) of the magnetic field which a magnetoresistive effect element senses in the case of the ratio of the amplitude of the magnitude | size of the magnetic field of a radial direction and a rotation direction differing in the conventional rotation angle detection apparatus. It is a wave form diagram which shows the change of the resistance value of the magnetoresistive effect element of the conventional rotation angle detection apparatus about the case where the ratio of the amplitude of the magnitude | size of the magnetic field of a radial direction and a rotation direction differs. It is a wave form diagram which shows the change of the output voltage of the conventional rotation angle detection apparatus about the case where the ratio of the amplitude of the magnitude | size of the magnetic field of a radial direction and a rotation direction differs. It is another waveform diagram which shows the change of the output voltage of the conventional rotation angle detection apparatus about the case where the ratio of the amplitude of the magnitude | size of the magnetic field of a radial direction and a rotation direction differs.

  DESCRIPTION OF SYMBOLS 1 Magnet rotor, 2 Cylindrical magnet, 3 Sensor device, 4, 4a-4c Differential amplifier, 5 Signal processing part.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, in each following embodiment, the same code | symbol is attached | subjected about the same component.

  In the following embodiment, a case where a magnetoresistive effect element whose magnitude of resistance changes depending on the direction of an applied magnetic field is used as a magnetic detection unit for detecting a magnetic field that changes as the magnet rotor rotates. explain. However, the same effect can be obtained even when other magnetic detection units are used. Hereinafter, the magnetoresistive effect element is simply referred to as “element”.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a rotation angle detection device of the present invention. The rotation angle detection device 10 includes a magnet rotor 1 on which a cylindrical magnet 2 is mounted, and a sensor device 3 that senses a magnetic field generated by the cylindrical magnet 2. The cylindrical magnet 2 has 2 m poles (m is an integer of 1 or more) in which N and S poles are alternately magnetized with a magnetization width λ along the circumferential surface. FIG. 1 shows a configuration diagram when m = 5. The sensor device 3 is arranged at a predetermined distance from the magnet rotor 1.

  FIG. 2 is a layout diagram of regions provided in the sensor device according to the first embodiment of the present invention. As shown in FIG. 2, the sensor device 3 is provided with a region A and a region B with a distance L therebetween. The element RA is arranged in the region A, the element RB is arranged in the region B, and the distance between the elements RA and RB is also set to L. Similarly, the distance between regions is assumed to be equal to the distance between elements arranged in the region.

FIG. 3 is a wiring diagram of the magnetoresistive effect element in the rotation angle detecting device according to the first embodiment of the present invention. As shown in FIG. 3, elements RA and RB are connected in series between a DC power supply (VCC) and a ground (GND). The sensor device 3 also includes a signal processing unit 5 that outputs the rotation angle of the magnet rotor 1 based on the midpoint potential (= output potential) Vout of the elements RA and RB. The distance L is expressed by the following formula (5), where λ is the magnetization width of the cylindrical magnet 2.

  As described above, when the amplitude of the magnitude of the magnetic field of the magnet rotor 1 is different between the radial direction and the rotational direction, third-order harmonic component distortion occurs in the detection signal Vout. Further, the third-order harmonic component causes the largest distortion of the detection signal Vout. Therefore, the behavior of the resistance value and the output potential Vout of each element will be described below by taking n = 3 and n = 5 as an example.

(When n = 3)
In FIG. 1, when the magnet rotor 1 rotates in the direction of the arrow, the magnetic pole moves in the direction of the arrow with respect to the sensor device 3 as shown in FIG. As the magnetic pole moves, the direction of the magnetic field sensed by the elements RA and RB changes, and the resistance values of the elements RA and RB also change as shown in FIG.

  When the magnitude P of the magnetic field in the radial direction is equal to the amplitude Q in the rotation direction, that is, when Q / P = 1, the resistance values of the elements RA and RB are sinusoidal as shown by thin lines in FIG. Change. On the other hand, when the amplitude Q of the magnitude of the magnetic field in the rotational direction is smaller than the amplitude P in the radial direction, for example, when Q / P = 0.7, the resistance values of the elements RA and RB are as shown by bold lines in FIG. It changes to a triangular wave shape.

  As shown in FIG. 2, the elements RA and RB are arranged with a distance L (= 2λ / n (n = 3)). Therefore, the resistance values of the elements RA and RB have a phase difference of 120 ° (= 180 ° × 2/3) as shown in FIG. Here, θ in FIG. 4 represents the phase angle of the magnet rotor 1, and is 360 ° for a magnetized single pole pair on the circumferential surface. The same applies to other drawings.

  The thick and thin lines in FIG. 5 are waveforms of the output potential Vout when L = λ and L = 2 / 3λ, respectively. FIG. 6 shows a difference signal between the waveform of the output potential Vout shown in FIG. 5 and a sine wave. The “sine wave” here is a sine wave in which the direct current component, amplitude, frequency, and phase are adjusted so that the difference from the output potential Vout is minimized. The same applies to FIG. 9, FIG. 13, FIG. 16, FIG. 22, FIG.

  In FIG. 6, when L = λ is compared with L = 2λ / 3, when L = 2λ / 3, that is, the elements RA and RB are 2/3 times the magnetization width λ of the cylindrical magnet 2. It can be seen that the output potential Vout is closer to a sine wave when arranged apart from each other. Therefore, when L = 2λ / 3, it can be said that the third-order harmonic component is suppressed and the level of distortion is reduced.

(When n = 5)
FIG. 7 shows resistance values of the elements RA and RB to which the fifth-order harmonic component is added. The resistance values of the elements RA and RB have a phase difference of 72 ° (= 180 ° × 2/5) as shown in FIG. It can be seen that the resistance values of the elements RA and RB are distorted by adding a fifth-order harmonic component, but the output potential Vout is close to a sine wave.

FIG. 8 shows a waveform of the output potential Vout when L = λ and L = 2 / 5λ. FIG. 9 shows a difference signal between the waveform of the output potential Vout and the sine wave shown in FIG. In FIG. 9 , when L = λ and L = 2λ / 5 are compared, when L = 2λ / 5, that is, the elements RA and RB are 2/5 times the magnetization width λ of the cylindrical magnet 2. It can be seen that the output potential Vout is closer to a sine wave when arranged apart from each other. Therefore, when L = 2λ / 5, it can be said that the fifth-order harmonic component is suppressed and the level of distortion is reduced.

  As described above, the elements RA and RB are arranged at a distance of 2 / n times the magnetization width λ, and the elements are arranged and connected as shown in FIG. It was found that harmonic components can be suppressed.

  As shown in FIG. 1 and the like, in this embodiment, the cylindrical magnet 2 magnetized so as to generate a magnetic field that creates a magnetic flux density distribution in the circumferential direction is used. However, as shown in FIG. You may use the cylindrical magnet 2 magnetized so that the magnetic field which produces magnetic flux density distribution may be produced. In that case, the sensor device 3 is disposed above or below the magnetic pole with the axial direction as the vertical direction. The same applies to the following embodiments.

Embodiment 2. FIG.
FIG. 10 is a wiring diagram of the magnetoresistive effect element in the rotation angle detecting device according to the second embodiment of the present invention. The rotation angle detection device according to the present embodiment is different from the configuration of the first embodiment in that two elements are arranged in the regions A and B, respectively, and a bridge circuit configured by four elements is provided. Further, a differential amplifier 4 is provided in the bridge circuit. Other configurations are the same as those of the first embodiment.

In the rotation angle detection apparatus 10 according to the present embodiment, two elements RA1 and RA2 are arranged in the area A of the sensor device 3, and two elements RB1 and RB2 are arranged in the area B, respectively. The elements RA1 and RA2 are arranged so as to sense a magnetic field having the same size and direction from the cylindrical magnet 2 . This also applies to the case where two elements are arranged in the same region.

  As shown in FIG. 10, elements RA1, RB2, RB1, and RA2 are arranged in the first arm Arm1 to the fourth arm Arm4 of the bridge circuit, respectively. The bridge circuit has a configuration in which the first arm and the fourth arm intersect and the second arm and the third arm intersect. That is, the elements arranged in the same region are arranged on the intersecting arms of the bridge circuit. The first arm and the third arm are connected in series between the DC power supply (VCC) and the ground (GND), and the second arm and the fourth arm are similarly connected between the DC power supply (VCC) and the ground (GND). Connect the arm in series. The first arm and the third arm are connected in parallel with the second arm and the fourth arm.

  The midpoint potential of the first and third arms is V1, and the midpoint potential of the second and fourth arms is V2. The midpoint of the first arm and the third arm is connected to the inverting input terminal (−) of the differential amplifier 4, and the midpoint of the second arm and the fourth arm is connected to the non-inverting input terminal (+) of the differential amplifier 4. Connecting. The differential amplifier 4 outputs a voltage Vout (= V2−V1). The signal processing unit 5 outputs the rotation angle of the magnet rotor 1 based on the output voltage Vout.

  Also in this embodiment, by arranging the elements RA1, RA2 and RB1, RB2 at a distance of 2 / n times the magnetization width λ of the cylindrical magnet 2, the nth-order harmonic component of the output voltage Vout. Can be suppressed. As in the case of the first embodiment, the case where n = 3 and n = 5 will be described.

(When n = 3)
When the amplitude P of the magnitude of the magnetic field in the rotational direction is smaller than the amplitude Q in the radial direction, for example, Q / P = 0.7, the resistance values of the elements RA1 and RB1 are triangular as shown by thin lines in FIG. It changes in a wave shape. In the present embodiment, the elements RA1 and RA2 and the elements RB1 and RB2 are arranged so as to sense magnetic fields having the same magnitude and direction from the cylindrical magnet 2, so that the resistance values of the elements RA1 and RA2 are equal, The resistance values of RB1 and RB2 are equal.

  The midpoint potential V1 of the elements RA1 and RB1 corresponds to the midpoint potential Vout of the elements RA and RB of the first embodiment. The output voltage Vout indicated by a bold line in FIG. 5 has a shape close to a sine wave. Similarly, it can be seen that the midpoint potential V2 has a shape close to a sine wave as shown by a thick line in FIG. The same applies to the midpoint potential V2 of the elements RA2 and RB2. Accordingly, as shown in FIG. 12, even when the output voltage Vout (= V2−V1), when L = λ (thin line) and L = 2λ / 3 (thick line) are compared, the case of L = 2λ / 3 That is, when the elements RA and RB are arranged at a distance 2/3 times the magnetization width λ of the cylindrical magnet 2, the output voltage Vout is closer to a sine wave. Therefore, when L = 2λ / 3, it can be said that the third-order harmonic component is suppressed and the level of distortion is reduced. This can also be confirmed in FIG. 13 showing the difference between the output voltage Vout and the sine wave.

(When n = 5)
FIG. 14 shows resistance values of the elements RA1 and RA2 and the elements RB1 and RB2 to which a fifth-order harmonic component is added. The resistance values of the elements RA1, RA2 and RB1, RB2 are distorted by adding fifth-order harmonic components as in the case of n = 3, but the midpoint potentials V1, V2 are close to sine waves. You can see that

FIG. 15 shows the waveform of the output voltage Vout (V2−V1) when L = λ and L = 2 / 5λ. FIG. 16 shows a difference signal between the waveform of the output voltage Vout shown in FIG. 15 and a sine wave. In FIG. 15, when L = λ and L = 2λ / 5 are compared, when L = 2λ / 5, that is, the elements RA and RB are 2/5 times the magnetization width λ of the cylindrical magnet 2. It can be seen that the output voltage Vout is closer to a sine wave when arranged apart from each other . I I, in the case of L = 2 [lambda] / 5, is suppressed fifth-order harmonic component, it can be said that the level of distortion is small.

  Next, advantages of configuring the bridge circuit will be described. In the present embodiment, elements RA1 and RA2 and elements RB1 and RB2 that sense the same magnetic field are arranged on the intersecting arms to constitute a bridge circuit. Therefore, out of the harmonic components added to the midpoint potentials V1 and V2, the even-order harmonics have opposite phases at V1 and V2. Since the output voltage Vout is a differential output of V1 and V2, even-order harmonics cancel each other. Thereby, only the odd order should be considered for the harmonic component of the output voltage Vout resulting from the difference in amplitude of the magnetic field magnitude between the rotational direction and the radial direction. Further, even when external noise is added to the output voltage Vout, noise corresponding to the second harmonic component can be suppressed.

  As described above, even in the case of the configuration of the present embodiment, as in the first embodiment, the regions A and B are arranged at a distance of 2/3 times the magnetization width λ of the cylindrical magnet 2, thereby providing a third order. It was found that harmonic components are suppressed and the level of distortion can be reduced. Furthermore, since the bridge circuit is configured, second harmonic components such as external noise can be suppressed.

Embodiment 3 FIG.
FIG. 17 is a wiring diagram of the magnetoresistive effect element in the rotation angle detecting device according to the third embodiment of the present invention. In the present embodiment, for example, as shown in FIG. 18, the sensor device 3 is provided with four regions A to D, and two elements are arranged in each region. The rotation angle detection device according to the present embodiment is different from the configuration of the second embodiment in that it has two bridge circuits and uses three differential amplifiers 4A to 4C. Other configurations are the same as those of the second embodiment.

  In the rotation angle detection apparatus 10 according to the present embodiment, the elements RA1 and RA2 are disposed in the region A of the sensor device 3, the elements RB1 and RB2 are disposed in the region B, the elements RC1 and RC2 are disposed in the region C, and the elements RD1 and RD2 are disposed in the region D. Are arranged respectively.

A bridge circuit A shown in FIG. 17 is configured using four elements RA1, RB1, RA2, and RB2. Further, the bridge circuit B is configured in the same manner as the bridge circuit A using the four elements RC1, RD1, RC2, and RD2. As shown in FIG. 17, the elements arranged in the same region are arranged on the intersecting arms of the bridge circuit.

  The bridge circuit A is provided with a differential amplifier 4A, and the bridge circuit B is provided with a differential amplifier 4B. The differential amplifier 4A outputs a differential voltage V12 (= V2-V1) between the midpoint potential V1 of the elements RA1 and RB1 and the midpoint potential V2 of the elements RA2 and RB2, and the differential amplifier 4B A differential voltage V34 (= V4-V3) between the midpoint potential V3 of RD1 and the midpoint potential V4 of the elements RC2 and RD2 is output. Further, the differential amplifier 4A is connected to the inverting input terminal (−) of the differential amplifier 4C, and the differential amplifier 4B is connected to the non-inverting input terminal (+) of the differential amplifier 4C. The differential amplifier 4C outputs a voltage Vout (= V34−V12). The signal processing unit 5 outputs the rotation angle of the magnet rotor 1 based on the output voltage Vout.

  Next, the distance between each area | region is demonstrated. In the present embodiment, the arrangement of the regions is determined so that harmonic components of two kinds of orders n1 and n2 can be suppressed.

Hereinafter, as an example of n1> n2, n1 = 3 and n2 = 2, that is, an arrangement capable of suppressing the second-order and third-order harmonic components will be described. Hereinafter, the distance between the region A and the region B is described as L _AB .

(Arrangement Example 3-1)
FIG. 18 is a layout diagram of regions provided in the sensor device of the rotation angle detection device according to the third embodiment of the present invention. In this arrangement example, the areas A to D are arranged so as to satisfy L _AB = L _CD = 2λ / n1 (n1 = 3) and L _AC = 2λ / n2 (n2 = 2). Thereby, the secondary and tertiary harmonic components can be suppressed.

FIG. 19 shows the resistance values of the elements of the bridge circuit A, the midpoint potentials V1 and V2, and the differential voltage V12 (= V2−V1) output from the differential amplifier 4A. FIG. 20 shows the resistance values of the elements of the bridge circuit B, the midpoint potentials V3 and V4, and the differential voltage V34 (= V4-V3) output from the differential amplifier 4B. Since L _AB = L _CD = 2λ / 3, the differential voltages V12 and V34 are waveforms in which third-order harmonic components are suppressed. FIG. 21 shows the output voltage Vout (= V4−V3) of the differential amplifier 4C. _{L AC} = L _BD = λ therefore, the output voltage Vout is a waveform harmonics of the secondary is further suppressed. The output voltage Vout has a waveform close to a sine wave with the third and second harmonic components suppressed. This can also be confirmed in FIG. 22 showing the difference between V12, V34 and Vout and the sine wave.

FIG. 23 is an alternative view of the arrangement of regions provided in the sensor device of the rotation angle detection device according to the third embodiment of the present invention. As shown in FIG. 23, even if the regions A to D are arranged so as to satisfy L _AB = 2λ / n1 (n1 = 3) and L _AC = L _BD = 2λ / n2 (n2 = 2), The same effect as the arrangement can be obtained. That is, when the arrangement of the areas C and D is reversed, the distance between the areas is equal to (2λ−2λ / n1). Similarly, when the arrangement of the areas A and B is reversed, the distance between the areas is equal to (2λ−2λ / n1). Further, when the arrangement of the areas A and C is reversed, the distance between the areas is equal to (2λ-2λ / n2).

(Arrangement Example 3-2)
In the above description, a case where n1> n2 and second-order and third-order harmonic components are suppressed has been described. Conversely, the same effect can be obtained when n1 <n2. Hereinafter, the case where the second-order and third-order harmonic components are suppressed with n1 = 2 and n2 = 3 will be described.

FIG. 24 is an alternative view of the arrangement of regions provided in the sensor device of the rotation angle detection device according to the third embodiment of the present invention. In this arrangement example, the areas A to D are arranged so as to satisfy L _AB = L _CD = 2λ / n1 (n1 = 2) and L _AC = 2λ / n2 (n2 = 3).

FIG. 25 shows the resistance values of the elements of the bridge circuit A, the midpoint potentials V1 and V2, and the differential voltage V12 (= V2−V1) output from the differential amplifier 4A. FIG. 26 shows the resistance values of the elements of the bridge circuit B, the midpoint potentials V3 and V4, and the differential voltage V34 (= V4-V3) output from the differential amplifier 4B. Since L _AB = L _CD = λ, the differential voltages V12 and V34 are waveforms in which second-order harmonic components are suppressed. FIG. 27 shows the output voltage Vout (= V4−V3) of the differential amplifier 4C. _{L AC = L BD = 2λ /} 3 because the output voltage Vout is a waveform harmonics of the third order is further suppressed. The output voltage Vout has a waveform close to a sine wave with the third and second harmonic components suppressed. This can also be confirmed in FIG. 28 showing the difference between V12, V34 and Vout and the sine wave.

FIG. 29 is an alternative view of the arrangement of regions provided in the sensor device of the rotation angle detection device according to the third embodiment of the present invention. As shown in FIG. 29, even if the regions A to D are arranged so as to satisfy L _AB = L _CD = 2λ / n1 (n1 = 2) and L _AC = 2λ / n2 (n2 = 3), The same effect as the arrangement can be obtained. That is, when the arrangement of the areas A and B is reversed, the distance between the areas is equal to (2λ−2λ / n1). Similarly, when the arrangement of the areas C and D is reversed, the distance between the areas is equal to (2λ−2λ / n1). Furthermore, when the arrangement of the areas A and C is reversed, the distance between the areas is equal to (2λ−2λ / n2).

Embodiment 4 FIG.
FIG. 30 is a wiring diagram of magnetoresistive elements in the rotation angle detection device according to the fourth embodiment of the present invention. In the present embodiment, the number of regions provided in the sensor device 3 is increased to increase the number p of harmonic components that can be suppressed (p is an integer of 1 or more). As shown in FIG. 30, the rotation angle detection device according to the present embodiment is different from the second embodiment in that it has one bridge circuit and a plurality of elements are arranged in each arm of the bridge circuit. Other configurations of the present embodiment are the same as those of the second embodiment.

(When p = 2)
As in the third embodiment, the sensor device 3 is provided with four regions A to D, and two elements are arranged in each region. Elements RA1 and RA2 are arranged in area A of sensor device 3, elements RB1 and RB2 are arranged in area B, elements RC1 and RC2 are arranged in area C, and elements RD1 and RD2 are arranged in area D, respectively.

  As shown in FIG. 30, elements RA1 and RD1 are provided in the first arm of the bridge circuit, elements RB2 and RC2 are provided in the second arm, elements RB1 and RC1 are provided in the third arm, and elements RA2 and RD2 are provided in the fourth arm. Deploy. The bridge circuit has a configuration in which the first arm and the fourth arm intersect and the second arm and the third arm intersect. That is, the elements arranged in the same region are arranged on the intersecting arms of the bridge circuit. The first arm and the third arm are connected in series between the DC power supply (VCC) and the ground (GND), and the second arm and the fourth arm are similarly connected between the DC power supply (VCC) and the ground (GND). Each arm is connected in series. The first arm and the third arm are connected in parallel with the second arm and the fourth arm. In addition, as long as it exists in the same arm, you may replace the order which connects an element.

  The midpoint potential of the first and third arms is V1, and the midpoint potential of the second and fourth arms is V2. The midpoint of the first arm and the third arm is connected to the inverting input terminal (−) of the differential amplifier 4, and the midpoint of the second arm and the fourth arm is connected to the non-inverting input terminal (+) of the differential amplifier 4. Connecting. The differential amplifier 4 outputs a voltage Vout (= V2−V1). The signal processing unit 5 outputs the rotation angle of the magnet rotor 1 based on the output voltage Vout.

  Similarly to the third embodiment, for example, as shown in FIG. 18, FIG. 23, FIG. 24, or FIG. 29, by providing regions A to D in the sensor device 3, harmonic components of two types of orders of n1 and n2 are obtained. Can be suppressed.

  As an example, FIG. 31 shows resistance values and midpoint potentials V1 and V2 of each element when n1 = 3 and n2 = 2. FIG. 32 shows the difference between the output voltages Vout and Vout of the differential amplifier 4 and the sine wave. It can be seen that the output voltage Vout has a waveform substantially similar to a sine wave.

  With the configuration of this embodiment, two types of harmonic components can be suppressed. Furthermore, there is an advantage that the number of differential amplifiers can be reduced as compared with the third embodiment.

(When p = 3)
FIG. 33 is an alternative view of the arrangement of regions provided in the sensor device of the rotation angle detection device according to the fourth embodiment of the present invention. In FIG. 30, eight elements are arranged. By using twice as many as 16 elements, harmonic components of three kinds of orders can be suppressed. As shown in FIG. 33, the sensor device 3 is provided with eight regions A to H. In the area A of the sensor device 3, the elements RA1, RA2, the elements RB1, RB2 in the area B, the elements RC1, RC2 in the area C, the elements RD1, RD2 in the area D, the elements RE1, RE2 in the area E, the area Elements RF1 and RF2 are arranged in F, elements RG1 and RG2 are arranged in area G, and elements RH1 and RH2 are arranged in area H, respectively.

For example, as shown in FIG. 33, regions A to H are divided into L _AB = L _CD = L _EF = L _GH = 2λ / n1, L _AC = L _EG = 2λ / n 2, L _AE = 2λ / n 3 (n 3 is (Integer of 2 or more).

  FIG. 34 is a wiring diagram of the magnetoresistive effect element in the rotation angle detecting device according to the fourth embodiment of the present invention. Elements are arranged on the first to fourth arms of the bridge circuit as shown in FIG. In addition, as long as it exists in the same arm, you may replace the order which connects an element.

  As in the case of p = 2, the differential amplifier 4 outputs the voltage Vout (= V2−V1). As a result, a voltage in which harmonic components of three orders of n1, n2 and n3 are suppressed is output. And the exact rotation angle of the magnet rotor 1 by which distortion was suppressed by the signal processing part 5 can be obtained.

(When p ≧ 4)
FIG. 35 is a table showing an example of the arrangement interval of each region and the wiring of each magnetoresistive element that can suppress p types of harmonic components in the rotation angle detection device according to the fourth embodiment of the present invention. According to this rule, harmonic components of four or more orders can be suppressed. In addition, as long as it exists in the same arm, you may replace the order which connects an element. Arrangement interval and the wiring is only an example, also by other configuration enables suppressing the p type harmonic component.

First, the arrangement of regions will be described. Region (1) to region (2 ^p ) are provided on the sensor device 3. Further, according to the rules of FIG. 35, the region ^{(2 k m- (2 k -1} )) and region ^{(2 k m- (2 k -1} ) +2 k-1), is disposed at a distance _{L k} (K and m are integers of 1 or more). In the region (j), two elements R (j) ₁ and element R (j) ₂ are arranged (j is an integer of 1 or more). The distance L _k is expressed by the following formula (6).

The elements R (1) _{1 to} R (2 ^p ) ₁ and elements R (1) _{2 to} R (2 ^p ) ₂ constitute a bridge circuit. The bridge circuit has a configuration in which the first arm and the fourth arm intersect and the second arm and the third arm intersect. As an example of the arrangement of elements, consider the case of p = 4. The elements R (1) _{1 to} R (16) _{1 correspond} to the elements RA1 to RP1, and the elements R (1) _{2 to} R (16) ₂ correspond to the elements RA2 to RP2, respectively. In the first arm of the bridge circuit, eight elements RA1, RD1, RF1, RG1, RJ1, RK1, RM1, RP1 connected in series are arranged. Eight elements RB2, RC2, RE2, RH2, RI2, RL2, RN2, and RO2 are arranged on the second arm. Eight elements RB1, RC1, RE1, RH1, RI1, RL1, RN1, and RO1 are arranged on the third arm. Eight elements RA2, RD2, RF2, RG2, RJ2, RK2, RM2, RP2 are arranged on the fourth arm.

Similarly, in the case of p ≧ 5, the elements are arranged in the above order on the first to fourth arms. Each arm has 2 ^p-1 elements. In addition, the elements arranged in the same region are arranged on the intersecting arms of the bridge circuit.

As in the case of p = 2 and 3, 2 ^p elements R (1) _{1 to} R (2 ^p ) ₁ connected in series are arranged between the DC power supply (VCC) and the ground (GND). Further, 2 ^p elements R (1) _{2 to} R (2 ^p ) ₂ connected in series are arranged between the DC power supply (VCC) and the ground (GND). The first arm and the third arm are connected in parallel with the second arm and the fourth arm.

  The differential amplifier 4 outputs a voltage Vout (= V2−V1) in which p-type harmonic components are suppressed. And the exact rotation angle of the magnet rotor 1 by which distortion was suppressed by the signal processing part 5 can be obtained.

Claims (3)

A rotating body in which N and S poles are alternately magnetized along a circumferential surface with a magnetization width λ;
Comprising first to eighth magnetic detectors for sensing a magnetic field generated by a rotating body,
The first magnetic detection unit and the fourth magnetic detection unit are arranged at the first detection position,
The second magnetic detection unit and the third magnetic detection unit are disposed at the second detection position,
The fifth magnetic detection unit and the eighth magnetic detection unit are disposed at the third detection position,
The sixth magnetic detection unit and the seventh magnetic detection unit are arranged at the fourth detection position,
The first detection position and a second detection position provided apart distance L _12,
And the third detection position and a fourth detection position provided apart distance L _12,
The first detection position and the third detection position provided apart distance L _13,
Between the first reference potential and the second reference potential, the first magnetic detection unit and the third magnetic detection unit connected in series, and the second magnetic detection unit and the fourth magnetic detection unit connected in series are connected in parallel. And
The first to fourth magnetic detectors constitute a bridge circuit,
The first magnetic detection unit and the fourth magnetic detection unit, the second magnetic detection unit and the third magnetic detection unit are respectively disposed on the arms where the bridge circuit intersects,
Between the third reference potential and the fourth reference potential, a fifth magnetic detection unit and a seventh magnetic detection unit connected in series, and a sixth magnetic detection unit and an eighth magnetic detection unit connected in series are arranged. ,
The fifth to eighth magnetic detectors constitute a bridge circuit,
The fifth magnetic detection unit and the eighth magnetic detection unit, the sixth magnetic detection unit and the seventh magnetic detection unit are respectively arranged on the arms where the bridge circuit intersects,
A first magnetic detection portion and the middle point potential _{V 1} of the third magnetic detection unit, the difference _{V 12 (= V 2 -V 1} ) of the second magnetic detection portion and the midpoint potential _{V 2} of the fourth magnetic detection unit and a fifth magnetic detection portion and the seventh magnetic detectors midpoint potential _{V 3} of the difference _{V 34 (= V 4 -V 3} ) the sixth magnetic detection portion and the midpoint potential _{V 4} of the 8 magnetic detection unit Based on the difference Vout (= V ₃₄ -V ₁₂ ), a signal corresponding to the rotation angle of the rotating body is output,

A rotation angle detecting device satisfying the relationship: A rotating body in which N and S poles are alternately magnetized along a circumferential surface with a magnetization width λ;
2 ^{p + 1} (p is an integer greater than or equal to 2) magnetic detection units for sensing the magnetic field generated by the rotating body,
Two magnetic detection units are arranged at 2 ^p detection positions, respectively.
The distance between the i-th detection position (i is an integer of 1 or more) and the j-th detection position (j is an integer of 1 or more different from i ) is L _ij ,
Between the first reference potential and second reference potential, and 2 ^p pieces of the magnetic detector connected in series, and a 2 ^p pieces of the magnetic detector connected in series are connected in parallel,
2 ^{p + 1} magnetic detection units constitute a bridge circuit,
Each arm of the bridge circuit is provided with 2 ^p-1 magnetic detectors,
The first arm and the fourth arm are arranged at a position where the bridge circuit intersects, and the second arm and the third arm are arranged at a position where the bridge circuit intersects,
Magnetic detection units arranged at the same detection position are arranged on the intersecting arms of the bridge circuit,
Based the midpoint potential _{V 1} of the first arm and the third arm, the second arm and the difference between Vout of the midpoint potential _{V 2} of the fourth arm ₍₌ V 2 -V _1), the angle of rotation of the rotor The corresponding signal is output,

A rotation angle detecting device satisfying the relationship: p = 2,
The first magnetic detection unit and the fourth magnetic detection unit are arranged at the first detection position,
The second magnetic detection unit and the third magnetic detection unit are disposed at the second detection position,
The sixth magnetic detection unit and the seventh magnetic detection unit are disposed at the third detection position,
The fifth magnetic detection unit and the eighth magnetic detection unit are disposed at the fourth detection position,
The distance L ₃₄ is equal to the distance L ₁₂
Between the first reference potential and the second reference potential, the first magnetic detection unit, the fifth magnetic detection unit, the third magnetic detection unit, and the seventh magnetic detection unit connected in series, and the second magnetism connected in series The detection unit, the sixth magnetic detection unit, the fourth magnetic detection unit, and the eighth magnetic detection unit are connected in parallel.
The first arm of the bridge circuit is provided with a first magnetic detector and a fifth magnetic detector,
The second arm of the bridge circuit has a second magnetic detector and a sixth magnetic detector,
A third magnetic detection unit and a seventh magnetic detection unit are arranged on the third arm of the bridge circuit,
The fourth arm of the bridge circuit has a fourth magnetic detector and an eighth magnetic detector,

The rotation angle detection device according to claim 2, wherein the relationship is satisfied.

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