JP6337842B2 - Rotation detector - Google Patents

Description

  The present invention relates to a rotation detection device that detects a rotation mode of a rotor.

  Conventionally, for example, Patent Document 1 proposes a rotation detection device configured to detect a rotation mode of a rotor. Specifically, a sensor chip in which a plurality of magnetoresistive elements are formed, a bias magnet that applies a bias magnetic field to each magnetoresistive element, and a processing circuit that performs signal processing based on the output of each magnetoresistive element are provided. A configuration of a rotation detecting device has been proposed. Each magnetoresistive element is arranged at a position facing the rotor, and constitutes a plurality of magnetoresistive element pairs forming a half-bridge circuit. The midpoint potential of each magnetoresistive element pair changes according to the rotation of the rotor.

Japanese Patent No. 4466355

  Here, the structure which produces | generates two 1st differential signals and 2nd differential signals from the output of three magnetoresistive element pairs can be considered. When the output of each magnetoresistive element pair is defined as A, B, and C, the first differential signal is obtained from (A−B) − (B−C). The first differential signal is a signal for detecting the crest / valley center of the rotor. The second differential signal is obtained from (AC). The second differential signal is a signal for discriminating mountains and valleys. Therefore, A and C of the outputs of each magnetoresistive element pair are parameters common to the two differential signals.

  In the above configuration, when the gap between the rotation detection device and the rotor increases, the change in the magnetic field of the bias magnet with respect to the teeth of the rotor becomes dull. For this reason, since the signal amplitude of each of the first differential signal and the second differential signal becomes small, there is a problem that the accuracy of the output signal corresponding to the center of the tooth length of the rotor is lowered. Therefore, it is conceivable to increase the signal amplitude of the first differential signal and the second differential signal by changing the position of any of the three magnetoresistive element pairs in the sensor chip.

  However, since the output of one of the three magnetoresistive element pairs is a parameter common to the two differential signals, the signal amplitudes of the two differential signals are in a trade-off relationship. That is, changing the position of one of the three magnetoresistive element pairs increases the signal amplitude of one of the first differential signal and the second differential signal, but decreases the other signal amplitude. turn into. As described above, since the signal amplitudes of the first differential signal and the second differential signal are limited, it is difficult to expand the detectable gap of the rotation detection device with respect to the rotor.

  An object of the present invention is to provide a rotation detection device capable of expanding a detectable gap with respect to a rotor in view of the above points.

  In order to achieve the above object, according to the first aspect of the present invention, in accordance with the rotation of the gear-type rotor (10) in which the convex portions (12) and the concave portions (13) are alternately provided in the rotation direction, the resistance value is increased. And a plurality of magnetoresistive element pairs (31 to 35) that change and a bias magnet (21) that applies a bias magnetic field to the plurality of magnetoresistive element pairs, and a plurality of magnetoresistive elements as the rotor rotates. A detection unit (30) that generates a main signal having a waveform corresponding to the concavo-convex structure of the convex part and the concave part and a sub signal having a waveform having a phase with respect to the main signal based on a change in the resistance value of the element pair. ).

  In addition, a binarization threshold value for binarizing the main signal and the sub signal is provided, the main signal and the sub signal are input from the detection unit, the main signal is compared with the binarization threshold value, and the main signal is set to 2 In addition to generating a digitized position signal, a phase signal obtained by binarizing the phase signal by comparing the sub-signal and the binarization threshold value is generated, and the position signal is used as center passage information of the convex portion. Is provided with a determination circuit section (40) having the rotation mode information of the rotor.

  The plurality of magnetoresistive element pairs are disposed farther from the rotor than the end (21a) on the rotor side of the bias magnet, and the first magnetoresistive element pair (31) of the plurality of magnetoresistive element pairs. The second magnetoresistive element pair (32) and the third magnetoresistive element pair (33) are a fourth magnetoresistive element pair (34) and a fifth magnetoresistive element pair (35) of the plurality of magnetoresistive element pairs. ) Is arranged farther from the end than.

  The second magnetoresistive element pair is disposed in a range surrounded by the first magnetoresistive element pair, the third magnetoresistive element pair, the fourth magnetoresistive element pair, and the fifth magnetoresistive element pair.

  The detection unit generates a position signal based on the outputs of the first magnetoresistive element pair, the second magnetoresistive element pair, and the third magnetoresistive element pair, and the fourth magnetoresistive element pair and the fifth magnetoresistive element pair. A phase signal is generated on the basis of the output of.

  According to this, the signal amplitude of the main signal increases as the first magnetoresistive element pair and the third magnetoresistive element pair move away from the rotor. On the other hand, the signal amplitude of the sub signal increases independently from the main signal as the fourth magnetoresistive element pair and the fifth magnetoresistive element pair approach the rotor. That is, the signal amplitudes of both the main signal and the sub signal can be maximized by arranging each magnetoresistive element pair so that both the signal amplitudes of the main signal and the sub signal are increased. For this reason, even if the gap with respect to the rotor becomes large, the signal amplitude of the main signal and the sub signal can be secured. Therefore, the detectable gap with respect to the rotor can be enlarged.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is the figure which showed the arrangement | positioning relationship between the rotation detection apparatus which concerns on one Embodiment of this invention, and a gear type rotor. It is the figure which showed the circuit structure of the rotation detection apparatus shown by FIG. It is the figure which showed the signal amplitude of the main signal (S1) and sub signal (S2) according to the position of each magnetoresistive element pair. It is a timing chart for demonstrating the action | operation of a rotation detection apparatus. It is the figure which showed the determination conditions of the rotation direction of a rotor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The rotation detection device according to the present invention is used, for example, as a crank angle determination device for an internal combustion engine. As shown in FIG. 1, a rotation detection device 20 is disposed so as to face the outer peripheral portion 11 of a gear-type rotor 10 fixed to a crankshaft of an engine that is an internal combustion engine. Convex portions 12 and concave portions 13 are alternately provided in the rotational direction on the outer peripheral portion 11 of the rotor 10. In FIG. 1, a part of the outer peripheral portion 11 of the rotor 10 is shown in a straight line.

  The rotation detection device 20 is configured to detect the rotation mode of the rotor 10. The rotation detection device 20 includes a cylindrical bias magnet 21 and a sensor chip 22 disposed at a predetermined position with respect to the bias magnet 21.

  The bias magnet 21 serves to increase the detection sensitivity of the magnetic field of the sensor chip 22 by a certain amount by applying a bias magnetic field to the sensor chip 22. A sensor chip 22 is disposed in the hollow portion of the bias magnet 21.

  The sensor chip 22 is configured as a semiconductor chip. The sensor chip 22 includes a detection unit 30 configured to output a signal corresponding to the position of the convex portion 12, that is, the crank angle as the rotor 10 rotates. The detection unit 30 includes a first magnetoresistive element pair 31, a second magnetoresistive element pair 32, a third magnetoresistive element pair 33, a fourth magnetoresistive element pair 34, whose resistance values change as the rotor 10 rotates. A fifth magnetoresistive element pair 35 is provided.

  Each of the magnetoresistive element pairs 31 to 35 is configured as a half bridge circuit. Specifically, as shown in FIG. 2, the first magnetoresistive element pair 31 includes two magnetoresistive elements 31a and 31b connected in series between a power supply (Vcc) and a ground (GND). ing. The first magnetoresistive element pair 31 detects a change in resistance value when each of the magnetoresistive elements 31 a and 31 b is affected by the magnetic field as the rotor 10 rotates. The first magnetoresistive element pair 31 outputs the voltage at the midpoint 31c of each of the magnetoresistive elements 31a and 31b as a waveform signal based on the change in the resistance value.

  The second to fifth magnetoresistive element pairs 32 to 35 have the same configuration as the first magnetoresistive element pair 31. The second magnetoresistive element pair 32 is composed of two magnetoresistive elements 32a and 32b. And the voltage of the midpoint 32c of each magnetoresistive element 32a, 32b is output as a waveform signal. The third magnetoresistive element pair 33 is composed of two magnetoresistive elements 33a and 33b. And the 3rd magnetoresistive element pair 33 outputs the voltage of the midpoint 33c of each magnetoresistive element 33a, 33b as a waveform signal.

  The fourth magnetoresistive element pair 34 includes two magnetoresistive elements 34a and 34b. And the voltage of the middle point 34c of each magnetoresistive element 34a, 34b is output as a waveform signal. The fifth magnetoresistive element pair 35 is composed of two magnetoresistive elements 35a and 35b. And the 5th magnetoresistive element pair 35 outputs the voltage of the midpoint 35c of each magnetoresistive element 35a, 35b as a waveform signal.

  Further, the detection unit 30 includes first to fourth operational amplifiers 36 to 39 in addition to the magnetoresistive element pairs 31 to 35. When the midpoint potential of the midpoint 31c of the first magnetoresistive element pair 31 is defined as A and the midpoint potential of the midpoint 32c of the second magnetoresistive element pair 32 is defined as B, the first operational amplifier 36 A differential amplifier configured to calculate −B and output the result. When the midpoint potential of the midpoint 33c of the third magnetoresistive element pair 33 is defined as C, the second operational amplifier 37 is a differential amplifier configured to calculate B-C and output the result. is there.

  The third operational amplifier 38 inputs A-B from the first operational amplifier 36 and B-C from the second operational amplifier 37, calculates (A-B)-(B-C), and calculates the result as S1 ( = A + C-2B) is a differential amplifier configured to output. The signal of S1 is a main signal having a waveform corresponding to the concavo-convex structure of the convex portion 12 and the concave portion 13 of the rotor 10. For example, the main signal S <b> 1 is a signal having a waveform in which the amplitude is maximum or minimum at the concave portion 13, the convex portion 12, and the edge portion of the rotor 10.

  The main signal S1 is a signal that greatly reflects the influence of -2B. This is because the magnetization directions of the free magnetic layers of the first magnetoresistive element pair 31 and the third magnetoresistive element pair 33 slightly swing with respect to the concavo-convex structure of the rotor 10, while the free magnetic layer of the second magnetoresistive element pair 32. This is because the magnetization direction of the magnetic field fluctuates greatly with respect to the concave-convex structure of the rotor 10.

  When the midpoint potential of the midpoint 34c of the fourth magnetoresistive element pair 34 is defined as L and the midpoint potential of the midpoint 35c of the fifth magnetoresistive element pair 35 is defined as R, the fourth operational amplifier 39 is L This is a differential amplifier configured to calculate −R and output the result as S2. The signal of S2 is a sub signal having a waveform having a phase difference with respect to the main signal S1. For example, the sub signal S <b> 2 is a signal having a waveform in which the amplitude is maximum at the center of the convex portion 12 of the rotor 10 and the amplitude is minimum at the center of the concave portion 13 in the rotational direction.

  As described above, the detection unit 30 detects the main signal S1 (= (A−B) − () based on the outputs of the first magnetoresistive element pair 31, the second magnetoresistive element pair 32, and the third magnetoresistive element pair 33. BC)) is generated. Further, the detection unit 30 generates the sub signal S2 (= LR) based on the outputs of the fourth magnetoresistive element pair 34 and the fifth magnetoresistive element pair 35. Note that each of the operational amplifiers 36 to 39 is configured to output the signal after adjusting the offset.

  The rotation detection device 20 includes a determination circuit unit 40 that generates a signal corresponding to the rotation mode of the rotor 10 detected by the detection unit 30. The determination circuit unit 40 may be formed on the sensor chip 22 described above, or may be formed on another semiconductor chip (not shown).

  The determination circuit unit 40 includes a threshold value generation unit 41, a first comparator 42, a second comparator 43, and a control unit 44. The threshold generation unit 41 includes two resistors 41a and 41b connected in series between a power supply (Vcc) and a ground (GND). The potential at the midpoint 41c of the resistors 41a and 41b is set as a binarization threshold. The binarization threshold value is used as a threshold value for binarizing the main signal S1 and the sub signal S1.

  The first comparator 42 receives the main signal S <b> 1 from the third operational amplifier 38 of the detection unit 30 and receives the binarization threshold value from the threshold value generation unit 41. Then, the first comparator 42 compares the main signal S1 with the binarization threshold value and generates a position signal obtained by binarizing the main signal S1.

  The second comparator 43 receives the sub signal S <b> 2 from the fourth operational amplifier 39 of the detection unit 30 and also receives the binarization threshold value from the threshold value generation unit 41. Then, the second comparator 43 compares the sub signal S2 with the binarization threshold value to generate a phase signal obtained by binarizing the sub signal S2.

  The control unit 44 is a control circuit that inputs a position signal from the first comparator 42 as center passage information of the convex portion 12 and inputs a phase signal from the second comparator 43 as rotation mode information of the rotor 10. The control unit 44 has a function of determining whether the rotation direction of the rotor 10 is normal rotation or reverse rotation based on the center passage information and the rotation mode information. The control unit 44 outputs the position signal and information on the rotation direction of the rotor 10 to an external device (not shown) via the output terminal 23 (Vout).

  The above is the overall configuration of the rotation detection device 20 according to the present embodiment. The rotation detection device 20 includes a power supply terminal 24 (Vcc) and a ground terminal 25 (GND) connected to an external device. The rotation detection device 20 is configured to be supplied with power from an external device via these terminals 24 and 25.

  Next, the arrangement relationship of the magnetoresistive element pairs 31 to 35 in the sensor chip 22 will be described. As shown in FIG. 1, each of the magnetoresistive element pairs 31 to 35 is arranged farther from the rotor 10 than the end 21 a on the rotor 10 side of the bias magnet 21. That is, all the magnetoresistive element pairs 31 to 35 are arranged in the hollow portion of the bias magnet 21.

  The first magnetoresistive element pair 31, the second magnetoresistive element pair 32, and the third magnetoresistive element pair 33 among the magnetoresistive element pairs 31 to 35 are the plurality of magnetoresistive element pairs 31 to 35. The fourth magnetoresistive element pair 34 and the fifth magnetoresistive element pair 35 are arranged farther from the end 21 a of the bias magnet 21 than the fourth magnetoresistive element pair 34 and the fifth magnetoresistive element pair 35. That is, the magnetoresistive element pairs 31 to 33 for generating the main signal S1 are further away from the end 21a of the bias magnet 21 than the magnetoresistive element pairs 34 and 35 for generating the sub signal S2. .

  The second magnetoresistive element pair 32 is disposed in a range surrounded by the first magnetoresistive element pair 31, the third magnetoresistive element pair 33, the fourth magnetoresistive element pair 34, and the fifth magnetoresistive element pair 35. Has been. The range is the maximum range formed by connecting the magnetoresistive element pairs 31, 33 to 35 on one surface of the semiconductor chip constituting the sensor chip 22.

  Further, the second magnetoresistive element pair 32 is disposed closer to the fourth magnetoresistive element pair 34 and the fifth magnetoresistive element pair 35 than the first magnetoresistive element pair 31 and the third magnetoresistive element pair 33. As a result, the influence of -2B is greatly reflected in the main signal S1. That is, in the −X direction, the accuracy at the center arrangement of the teeth is improved. In the −Y direction, the amplitude is improved on the side of each magnetoresistive element pair 34, 35. For this reason, the detectable gap of the rotation detection device 20 can be enlarged.

  Here, the fourth magnetoresistive element pair 34, the second magnetoresistive element pair 32, and the fifth magnetoresistive element pair 35 are magnetic flux densities of magnetic fields formed on the end 21a side of the hollow part of the bias magnet 21. Is preferably disposed at a certain position or more. Thereby, the detection sensitivity of the 4th magnetoresistive element pair 34, the 2nd magnetoresistive element pair 32, and the 5th magnetoresistive element pair 35 can be improved.

  In a situation where the rotation detection device 20 is not affected by the rotor 10, a bias magnetic field along the central axis of the bias magnet 21 is applied to the second magnetoresistive element pair 32. On the other hand, a bias magnetic field for winding the end of the bias magnet 21 is applied to each of the other magnetoresistive element pairs 31, 33 to 35.

  Specifically, in each of the other magnetoresistive element pairs 31, 33 to 35, a magnetic field directed outward from the central axis of the bias magnet 21 is applied. A symmetric bias magnetic field is applied to the first magnetoresistive element pair 31 and the third magnetoresistive element pair 33 about the central axis of the bias magnet 21. Further, a symmetrical bias magnetic field is applied to the fourth magnetoresistive element pair 34 and the fifth magnetoresistive element pair 35 with the central axis of the bias magnet 21 as the center.

  The arrangement of each of the magnetoresistive element pairs 31 to 35 is based on the following studies by the inventors. First, the radial distance of the rotor 10 is defined as Y with the end 21a of the bias magnet 21 as a reference. A direction perpendicular to Y is assumed to be X.

  The inventors examined the change in the signal amplitude of the main signal S1 when the Y value of the first magnetoresistive element pair 31 and the third magnetoresistive element pair 33 was changed. In addition, the inventors examined the change in the signal amplitude of the sub signal S2 when the Y value of the fourth magnetoresistive element pair 34 and the fifth magnetoresistive element pair 35 was changed.

  As a result, as shown in FIG. 3, the signal amplitude increases as Y increases with respect to the main signal S1, that is, as the first magnetoresistive element pair 31 and the third magnetoresistive element pair 33 move away from the end 21a of the bias magnet 21. Became larger. On the other hand, the signal amplitude of the sub-signal S2 increases as Y decreases, that is, as the fourth magnetoresistive element pair 34 and the fifth magnetoresistive element pair 35 approach the end 21a of the bias magnet 21.

  From the above results, the signal amplitude of the main signal S1 can be increased by moving the first magnetoresistive element pair 31 and the third magnetoresistive element pair 33 that generate the main signal S1 away from the end 21a of the bias magnet 21. . Further, by bringing the fourth magnetoresistive element pair 34 and the fifth magnetoresistive element pair 35 that generate the subsignal S2 close to the end 21a of the bias magnet 21, the signal of the subsignal S2 regardless of the signal amplitude of the main signal S1. The amplitude can be increased. That is, the signal amplitude of the sub signal S2 can be adjusted independently from the signal amplitude of the main signal S1.

  Next, the operation of the rotation detection device 20 will be described. First, when the rotor 10 rotates, the main signal S1 and the sub signal S2 are acquired by the detection unit 30 based on the change in the gap between the detection unit 30 and the outer peripheral portion 11 of the rotor 10, as shown in FIG. .

  The main signal S1 is a signal having a waveform that exceeds the binarization threshold at the center of the rotation direction of the convex portion 12 of the rotor 10. On the other hand, the sub signal S2 is a signal having a phase difference with respect to the main signal S1, specifically, a waveform having a maximum amplitude at the rotation center of the convex portion 12 of the rotor 10.

  The main signal S1 acquired by the detection unit 30 is compared with the binarization threshold by the first comparator 42 of the determination circuit unit 40. When the signal amplitude of the main signal S1 is larger than the binarization threshold, for example, the first comparator 42 generates a position signal of Hi, and when the signal amplitude of the main signal S1 is smaller than the binarization threshold, for example.

  The sub-signal S2 acquired by the detection unit 30 is compared with the binarization threshold by the second comparator 43 of the determination circuit unit 40. When the amplitude of the sub signal S2 is larger than the binarization threshold, for example, the second comparator 43 generates a phase signal of Hi, and when the amplitude of the sub signal S2 is smaller than the binarization threshold, for example.

  As described above, the main signal S1, the sub signal S2, the position signal, and the phase signal are generated as the rotor 10 rotates, and the position signal and the phase signal are input to the control unit 44. Accordingly, the determination circuit unit 40 performs processing for outputting the position signal as an output signal to an external device.

  Further, the control unit 44 determines whether the rotation direction of the rotor 10 is normal rotation or reverse rotation based on the center passage information of the position signal and the rotation mode information of the phase signal.

  First, when the rotation direction of the rotor 10 is normal rotation, the amplitude of the main signal S1 becomes smaller than the binarization threshold before and after the time point T1. For this reason, the position signal changes from Hi to Lo. Further, since the signal amplitude of the sub-signal S2 is larger than the binarization threshold value, the binarized phase signal is Hi. Therefore, the control unit 44 determines that the rotor 10 is rotating forward because both the position signal falls from Hi to Lo and the phase signal is Hi.

  On the other hand, when the rotation direction of the rotor 10 is reverse, the amplitude of the main signal S1 becomes larger than the binarization threshold before and after the time point T1. For this reason, the position signal changes from Lo to Hi. Further, since the signal amplitude of the sub-signal S2 is larger than the binarization threshold value, the binarized phase signal is Hi. Therefore, the controller 44 determines that the rotor 10 is rotating in reverse because both the position signal rises from Lo to Hi and the phase signal is Hi.

  The above determination is the same before and after the time point T2. That is, the control unit 44 determines the rotation direction of the rotor 10 by determining whether or not the condition shown in FIG. 5 is satisfied.

  As described above, the first to third magnetoresistive element pairs 31 to 33 necessary for generating the main signal S1, the fourth magnetoresistive element pair 34 and the fifth magnetoresistive element pair necessary for generating the sub signal S2. 35 is divided into the respective configurations. For this reason, each magnetoresistive element pair 31-35 can be arrange | positioned so that the signal amplitude of both main signal S1 and sub signal S2 may become large. Accordingly, the signal amplitudes of both the main signal S1 and the sub signal S2 can be maximized.

  As described above, since the signal amplitudes of both the main signal S1 and the sub signal S2 can be increased, the signal amplitudes of the main signal S1 and the sub signal S2 even when the gap of the rotation detection device 20 with respect to the rotor 10 is increased. Is not reduced. Therefore, the detectable gap of the rotation detection device 20 with respect to the rotor 10 can be enlarged.

(Other embodiments)
The configuration of the rotation detection device 20 shown in each of the above embodiments is an example, and is not limited to the configuration shown above, and may be another configuration that can realize the present invention. For example, a binarization threshold value may be set for each of the comparators 42 and 43.

  In addition, the comparators 42 and 43 may have hysteresis characteristics. In this case, the first comparator 42 has the first binarization threshold value when the main signal S1 becomes smaller than the binarization threshold value. When the main signal S1 becomes larger than the binarization threshold, the binarization threshold is set to be a second value smaller than the first value. That is, the first comparator 42 switches the binarization threshold value to the first value or the second value according to the main signal S1. As a result, even if noise or the like enters the main signal S1, the main signal S1 does not easily exceed the binarization threshold value, and noise resistance is improved.

  Similarly, when the sub signal S2 becomes smaller than the binarization threshold, the second comparator 43 has the first value when the sub signal S2 becomes smaller than the binarization threshold, and when the sub signal S2 becomes larger than the binarization threshold. The binarization threshold is set to be a second value smaller than the first value.

  In the above embodiment, the second magnetoresistive element pair 32 is disposed on the fourth magnetoresistive element pair 34 and the fifth magnetoresistive element pair 35 side of the first magnetoresistive element pair 31 and the third magnetoresistive element pair 33. This is an example of an arrangement. Therefore, the position of the second magnetoresistive element pair 32 may be another position.

  In the above embodiment, the rotor 10 is fixed to the crankshaft of an engine that is an internal combustion engine, but the application of the rotation detection device 20 is not limited to the internal combustion engine.

  In the above embodiment, the phase signal indicating the rotation mode information of the rotor 10 is used to determine the rotation direction of the rotor 10, but this is an example of the use of the phase signal. Therefore, for example, the phase signal may be used for permission or prohibition when the control unit 44 outputs the position signal to an external device.

DESCRIPTION OF SYMBOLS 10 Rotor 12 Convex part 13 Concave part 21 Bias magnet 30 Detection part 31-35 Magnetoresistive element pair 40 Determination circuit part

Claims (3)

A plurality of magnetoresistive element pairs (31 to 35) whose resistance values change with the rotation of the gear-type rotor (10) in which the convex portions (12) and the concave portions (13) are alternately provided in the rotation direction; A bias magnet (21) for applying a bias magnetic field to the plurality of magnetoresistive element pairs, and based on a change in resistance value of the plurality of magnetoresistive element pairs as the rotor rotates. A detection unit (30) for generating a main signal having a waveform corresponding to the concavo-convex structure of the concave portion and the concave portion, and a sub signal having a waveform having a phase with respect to the main signal,
A binarization threshold value for binarizing the main signal and the sub signal; the main signal and the sub signal are input from the detection unit; and the main signal and the binarization threshold value are compared. And generating a position signal obtained by binarizing the main signal, generating a phase signal by binarizing the phase signal by comparing the sub signal and the binarization threshold value, and converting the position signal to the convex shape. Determination circuit unit (40) having the phase signal as the rotation mode information of the rotor,
With
The plurality of magnetoresistive element pairs are arranged farther from the rotor than the end (21a) on the rotor side of the bias magnet, and the first magnetoresistive of the plurality of magnetoresistive element pairs. The element pair (31), the second magnetoresistive element pair (32), and the third magnetoresistive element pair (33) are a fourth magnetoresistive element pair (34) and a fifth magnetoresistive element pair among the plurality of magnetoresistive element pairs. The magnetoresistive element pair (35) is arranged farther from the end than the pair,
The second magnetoresistive element pair is disposed in a range surrounded by the first magnetoresistive element pair, the third magnetoresistive element pair, the fourth magnetoresistive element pair, and the fifth magnetoresistive element pair. And
The detection unit generates the main signal based on outputs of the first magnetoresistive element pair, the second magnetoresistive element pair, and the third magnetoresistive element pair, and the fourth magnetoresistive element pair and The rotation detection device generating the sub signal based on an output of the fifth magnetoresistive element pair.   The second magnetoresistive element pair is disposed closer to the fourth magnetoresistive element pair and the fifth magnetoresistive element pair than the first magnetoresistive element pair and the third magnetoresistive element pair. The rotation detection device according to claim 1.   The determination circuit unit determines whether the rotation direction of the rotor is normal rotation or reverse rotation based on the center passage information and the rotation mode information. Rotation detection device.

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