JP2009192263A - Rotation detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation detection device capable of improving detection accuracy in a simple structure. <P>SOLUTION: A rotation detection device 100 comprises: first and second magnetized zones 30a, 30b formed so that the positions of the north and south poles are shifted at a predetermined angle in a rotating direction of a rotor 10; and first and second magnetic detection elements 20a, 20b respectively disposed facing the first and second magnetized zones 30a, 30b, as magnetic detection elements. Therefore, the first and second magnetic detection elements 20a, 20b output phase-shifted electric signals according to the rotation of the rotor 10. With the use of this phase shift it is possible to improve the detection resolution of the rotation of the rotor 10 or to amplify the amplitude of electric signals. Thus, the rotation angle or speed of the rotor 10 can be accurately detected in a simple configuration in which simply the first and second magnetic detection elements 20a, 20b are arranged corresponding to the first and second magnetized zones 30a, 30b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rotation detection device that detects rotation of a rotating body using a magnetoresistive element.

  Conventionally, as a rotation detection device, for example, a device described in Patent Document 1 is known. In Patent Document 1, the rotation detection device includes a pulsar ring and a sensor device. Pulsaring has two magnetic generation layers in which a plurality of magnetic generation portions are formed at equal pitches in the circumferential direction, and these magnetic generation layers are overlapped in the radial direction so that different magnetic poles face each other. .

The sensor device includes a magnetic sensor opposed to the pulsar ring, a magnetism generating member opposed to the magnetic sensor via the pulsar ring, and a magnetic flux density of magnetism from the magnetism generating member and the pulsar ring. And a magnetic flux collecting member led to the sensor. Thereby, since the magnetic flux density of the pulsar ring and the magnetic flux density of the magnetism generating member are synthesized, the absolute value of the signal output output from the sensor can be increased.
JP 2004-170344 A

  However, in the rotation detection device described in Patent Document 1, in order to increase the absolute value of the signal output output from the magnetic sensor, a magnetic generation member is provided in addition to the magnetic generation part of the pulsar ring. The magnetism generating member is disposed at a position facing the magnetic sensor via the pulsar ring. For this reason, it is necessary to provide a magnetic flux collecting member for defining the positional relationship with the sensor. As described above, in the rotation detection device described in Patent Document 1, the magnetic sensor and the magnetic generation member are arranged with the magnetic generation unit of the pulsar ring interposed therebetween, and the magnetic flux collecting unit for holding the magnetic sensor and the magnetic generation member is used. Since a member is required, the structure is complicated.

  In view of the above problems, an object of the present invention is to provide a rotation detection device capable of improving detection accuracy with a simple structure.

  In order to achieve the above object, the rotation detecting device according to claim 1 is rotatably provided having a magnetized band in which N poles and S poles are alternately magnetized so as to form a ring shape as a whole. A substantially disk-shaped rotor, and a magnetic detection element that is disposed facing the magnetized band and converts a change in direction of a magnetic field generated by the magnetized band accompanying rotation of the rotor into an electric signal and outputs the electric signal A first and second magnetization bands provided in the rotor as the magnetization band, and the center positions of the first and second magnetization bands are The positions of the S pole and the N pole in the first and second magnetization bands are shifted from each other by a predetermined angle in the rotation direction of the rotor, and the magnetic detection element A first magnetic sensing element disposed to face the magnetized band; And having a second magnetic detecting elements arranged to face the second wear 磁帯.

  As described above, the rotation detection device according to claim 1 corresponds to the first and second magnetization bands formed by shifting the positions of the S pole and the N pole by a predetermined angle in the rotation direction of the rotor. A second magnetic detection element is provided. Therefore, the first and second magnetic detection elements output electrical signals whose phases are shifted from each other when the rotor rotates. By utilizing this phase shift, it is possible to increase the rotation detection resolution of the rotor and amplify the amplitude of the electric signal. As a result, the rotation angle and rotation speed when the rotor rotates can be accurately detected with a simple configuration in which the first and second magnetic detection elements are simply provided corresponding to the first and second magnetization bands. It becomes possible to do.

  According to a second aspect of the present invention, the first magnetic detection element and the second magnetic detection element are caused by an angular shift between the S pole and the N pole in the first and second magnetization bands. A signal processing circuit may be provided that shapes the output waveform of the electrical signal in which the output phase difference is generated into a pulse signal and integrates the shaped pulse signal. As described above, by arranging the first and second magnetized bands to be shifted by a predetermined angle, the electric signals output from the first magnetic detection element and the second magnetic detection element have a predetermined phase difference. Arise. Therefore, by shaping and synthesizing these electric signals, the number of pulses output when the rotor rotates can be increased, so that the detection accuracy of the rotation detection device can be improved. The first and second magnetic detection elements are arranged so that the intervals between the pulse signals are substantially equal when the pulse signals obtained by shaping the electrical signals output from the first and second magnetic detection elements are integrated. It is preferable to set a deviation angle between the N pole and the S pole in the first and second magnetization bands with respect to the position of.

  According to a third aspect of the present invention, the first magnetization band and the second magnetization band are provided so as to be adjacent to each other in the rotor, and a boundary line between the first and second magnetization bands is provided. A third magnetic sensing element arranged so as to face the third magnetic sensing element in a radial direction of the rotor so as to straddle the first magnetic band and the second magnetic band. A detection axis may be provided, and a change in the direction of the magnetic field generated between the first and second magnetization bands by the rotation of the rotor may be converted into an electrical signal and output. Since the positions of the S and N poles in the first and second magnetization bands are deviated by a predetermined angle in the rotation direction of the rotor, the rotation of the rotor causes a gap between the first and second magnetization bands. The direction of the acting magnetic field changes periodically. Therefore, by arranging the third magnetic detection element having the detection axis in the radial direction of the rotor so as to face the first and second magnetization bands, the rotor is also rotated from the third magnetic detection element. A corresponding electrical signal can be obtained.

  The signal processing circuit shapes the electric signal output from the third magnetic detection element into a pulse signal and generates the electric signal from the first and second magnetic detection elements. The integrated pulse signal may be integrated. Thus, the detection resolution can be further improved by using the pulse signal output from the electrical signal of the third magnetic detection element.

  As described in claim 5, the first and second magnetized bands are formed so as to be opposed to each other by different magnetic poles, and are shifted by a predetermined angle in the rotation direction of the rotor, You may provide the differential amplifier circuit which carries out differential amplification of the output of the electric signal from which the direction change of the magnetic field of a said 1st magnetic detection element and a said 2nd magnetic detection element becomes a reverse phase. By arranging the first and second magnetization bands so that different magnetic poles face each other, an electrical signal having a phase difference of 2π / 2 periods (180 °) is output from the first and second magnetic detection elements. Is done. At this time, the amplitude of the output waveform can be amplified by a factor of the number of the magnetic detection elements by differentially amplifying the electric signal having the opposite phase. Increasing the amplitude of the output waveform makes it less susceptible to noise, so that the detection accuracy of the rotation detector can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
1A and 1B are diagrams for explaining a rotation detection device 100 according to the present embodiment, in which FIG. 1A is a front view illustrating a schematic configuration of the rotation detection device 100, and FIG. 1 is a side sectional view of a rotation detection device 100. FIG. 2A to 2C are graphs showing conceptual waveforms of electric signals output as the rotor 10 rotates, and FIG. 2A shows electric signals output from the magnetic detection element 20a. It is a graph which shows a waveform, (b) is a graph which shows the waveform of the electric signal output from the magnetic detection element 20b, (c) is a graph which shows the waveform of the electric signal output from the magnetic detection element 20c. . FIGS. 3A to 3C are graphs showing waveforms when the waveforms of the electrical signals in FIGS. 2A to 2C are converted into pulse signals, respectively, and FIG. It is a graph which shows the waveform which integrated the waveform of (c).

  As shown in FIGS. 1A and 1B, the rotation detection device 100 includes a rotor 10, a magnetic detection element 20, and a signal processing circuit (not shown).

  The rotor 10 is formed in a substantially disk shape and is rotatably provided. The rotor 10 has magnetized bands 30a and 30b in which N poles and S poles are alternately magnetized so as to form a ring shape as a whole on the disk-shaped side surface. In the present embodiment, the rotor 10 is made of, for example, a ferromagnetic material.

  The magnetic detection elements 20a, 20b, and 20c are arranged facing the magnetic bands 30a and 30b, and convert the direction change of the magnetic field generated by the magnetic bands 30a and 30b accompanying the rotation of the rotor 10 into an electric signal. Output. The magnetic detection elements 20a, 20b, and 20c are made of, for example, a ferromagnetic material having an anisotropic effect of magnetoresistance.

  In the present embodiment, as shown in FIG. 1A, the magnetized bands 30a and 30b include first magnetized bands 30a each formed in a ring shape so as to be adjacent to each other on the disk-shaped side surface of the rotor 10. It consists of the second magnetized band 30b. The center positions of the first magnetic band 30 a and the second magnetic band 30 b coincide with the rotation axis of the rotor 10. Further, the magnetic pole positions of the S pole and the N pole in the first magnetized band 30 a and the second magnetized band 30 b are formed so as to be shifted by a predetermined angle in the rotation direction of the rotor 10.

  Corresponding to the fact that the magnetic bands 30a and 30b are composed of the first magnetic band 30a and the second magnetic band 30b, the magnetic detection elements 20a, 20b, and 20c have the first magnetic band 30a. A first magnetic detection element 20a arranged to face the second magnetic detection element 20b, a second magnetic detection element 20b arranged to face the second magnetization band 30b, and a first magnetization band 30a. The third magnetic detection element 20c is disposed so as to face the boundary line with the second magnetic band 30b.

  The first to third magnetic detection elements 20a to 20c are formed, for example, on a common substrate 21 indicated by a dotted line in FIG. The first and second magnetic detection elements 20a and 20b are located in the vicinity of the center of the first and second magnetization bands 30a and 30b, and a positional relationship in which a phase difference of 2π / 3 occurs in the output electric signal. It arrange | positions on the board | substrate 21 so that it may become. That is, using the fact that the N and S poles of the first and second magnetization bands 30a and 30b are shifted by a predetermined angle, the first and second magnetic detection elements 20a and 20b can be adjusted to 2π / The first and second magnetic detection elements 20a and 20b are arranged on the substrate 21 so that electrical signals whose phases are shifted by 3 are output. Accordingly, by positioning and installing the substrate 21 so as to be at a predetermined position with respect to the rotor 10, an electrical signal whose phase is shifted by 2π / 3 from the first and second magnetic detection elements 20a and 20b. Will be output.

  Note that the detection axes of the first and second magnetic detection elements 20a and 20b are set so as to be parallel to the tangential direction of the first and second magnetization bands 30a and 30b having a ring shape. Therefore, when the rotor 10 rotates and the magnetic poles facing the first and second magnetic detection elements 20a and 20b alternately change between the N pole and the S pole, the first and second magnetic detection elements 20a and 20b. The direction of the magnetic flux acting on the film also changes periodically. For this reason, the first and second magnetic detection elements 20a and 20b output periodically changing electrical signals as shown in FIGS. 2 (a) and 2 (b), respectively.

  The third magnetic detection element 20c is disposed on the substrate 21 so as to face the boundary line between the first magnetic band 30a and the second magnetic band 30b. The third magnetic detection element 20c has a detection axis along the radial direction of the rotor 10 so as to straddle the first magnetization band 30a and the second magnetization band 30b. Since the positions of the S and N poles in the first and second magnetized bands 30a and 30b are shifted by a predetermined angle in the rotation direction of the rotor 10, the first and second rotations are caused by the rotation of the rotor 10. The direction of the magnetic field acting between the magnetized bands 30a and 30b changes periodically. Therefore, the third magnetic detection element having the detection axis in the radial direction of the rotor 10 responds to a change in the direction of the magnetic field acting between the first and second magnetization bands 30a and 30b, that is, the rotation state of the rotor 10 The electrical signal corresponding to is output.

  Here, the third magnetic detection element 20c is in response to the electric signals (see FIGS. 2A and 2B) output from the first and third magnetic detection elements 20a and 20b on the substrate 21. Each of the formation positions is determined so as to output an electrical signal whose phase is shifted by 2π / 3.

  A signal processing circuit (not shown) compares the electric signals output from the first to third magnetic detection elements 20a to 20c with a predetermined reference value, and the magnitude of the electric signal is equal to or larger than the predetermined reference value. A waveform shaping circuit that outputs a Hi signal in a case and outputs a Lo signal when lower than a predetermined reference value. By this waveform shaping circuit, the electrical signals output from the first to third magnetoresistive elements 20a to 20c are converted into the pulse signals shown in FIGS. 3A to 3C (waveform shaping), respectively. .

  Further, the signal processing circuit includes a pulse signal integration circuit that inputs each pulse signal shown in FIGS. 3A to 3C and outputs a Hi signal for a predetermined time with the rising of each pulse signal as a trigger. As described above, the first to third magnetic detection elements 20a to 20c make use of the fact that the magnetic poles of the first and second magnetization bands 30a and 30b are deviated by a predetermined angle, and 2π / 3 each from each other. It is configured to output electrical signals that are out of phase. Therefore, by integrating the pulse signals obtained by shaping these electrical signals in the signal integration circuit, as shown in FIG. 3D, the number of pulses output when the rotor 10 rotates can be increased. it can. For this reason, the detection resolution by the rotation detection device 100 can be improved, and the detection accuracy of the rotation detection device 100 can be improved.

  In particular, the present embodiment is configured such that when the pulse signals obtained by shaping the electrical signals output from the first to third magnetic detection elements 20a to 20c are integrated, the intervals between the pulse signals are substantially equal. ing. Accordingly, the detection resolution can be improved over the entire rotor 10 without partially increasing or decreasing the detection resolution.

  In the above-described example, the magnetic band is composed of two magnetic bands 30a and 30b, and the magnetic detection element is composed of three magnetic detection elements 20a to 20c. The number of detection elements may be the same, and the magnetic detection elements may be arranged so as to face different magnetization bands.

  For example, when three magnetic sensing elements are arranged for three magnetic bands, the magnetic poles in the three magnetic bands have an angular range of one set of N and S poles as one cycle. Further, it is preferable to form it so as to be shifted by 2π / 3 periods. For example, when four magnetic detection elements are arranged for four magnetized bodies, the magnetic poles of the four magnetized bands are preferably formed so as to be shifted by 2π / 4 cycles. Thus, when n magnetic detection elements are arranged for n magnetization bands, the magnetic poles of the n magnetization bands are formed so as to be shifted by 2π / n cycles.

  In this way, the plurality of magnetic detection elements corresponding to the plurality of magnetization bands are formed so as to be arranged on a straight line on a common substrate, and the arrangement direction thereof coincides with the radial direction of the rotor 10. If the substrate is arranged on the other hand, the intervals between the pulse signals can be made uniform when the pulse signals obtained from the magnetic detection elements are integrated. In this way, it is possible to accurately and easily perform the formation of the magnetic detection element on the substrate 21 and the arrangement of the substrate 21.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. 4A and 4B are views for explaining the rotation detection device 200 in the present embodiment, in which FIG. 4A is a front view showing a schematic configuration of the rotation detection device 200, and FIG. 2 is a side sectional view of a rotation detection device 200. FIG.

  As shown in FIGS. 4A and 4B, the rotation detection device 200 according to the present embodiment is similar to the rotation detection device 100 according to the first embodiment in that the rotor 40 and the magnetic detection elements 50a, 50b, and 50c are And a signal processing circuit (not shown). Similarly to the rotor 10 of the first embodiment, the rotor 40 is formed with two magnetized bands 60a and 60b adjacent to each other in a ring shape, and the first magnetized band 60a and the second magnetized band. In 60b, the position of the magnetic pole is shifted by a predetermined angle in the rotation direction of the rotor 40. Further, the first magnetic detection element 50a is disposed so as to face the first magnetization band 60a, the second magnetic detection element 50b is disposed so as to face the second magnetization band 60b, and the first The third magnetic sensing element 50c is arranged so as to face the boundary line between the first magnetized band 60a and the second magnetized band 60b.

  However, in the present embodiment, the first magnetic band 60 a and the second magnetic band 60 b are formed on the outer peripheral surface of the rotor 40, not on the side surface having the disk shape of the rotor 40. Therefore, the first to third magnetic detection elements 50 a to 50 c are also arranged on the outer peripheral surface side of the rotor 40, not on the disk-shaped side surface side of the rotor 40.

  Depending on the installation space of the rotation detection device 200, it may be considered that the magnetic detection element cannot be arranged on the disk-shaped side surface side of the rotor 40, but even in such a case, when there is a certain amount of space on the outer peripheral surface side of the rotor 40, By adopting the configuration of the present embodiment, the rotation detection device 200 can be arranged.

(Third embodiment)
Next, a rotation detection device 300 according to a third embodiment of the present invention will be described. FIG. 5 is a front view of the rotation detection device 300 for explaining the rotation detection device 300 in the present embodiment. FIG. 6A is a graph showing waveforms of electric signals output from the magnetic detection elements 80a and 80b as the rotor 70 rotates, and FIG. 6B is an electric signal output from the magnetic detection elements 80a and 80b. It is a graph which shows the waveform which differentially amplified.

  As shown in FIG. 5, the rotation detection device 300 according to the present embodiment is also configured by a rotor 70, magnetic detection elements 80 a and 80 b, and a signal processing circuit (not shown), like the rotation detection device 100 according to the first embodiment. The Two magnetization bands 90a and 90b are formed on the rotor 70, the first magnetic detection element 80a is disposed so as to face the first magnetization band 90a, and the second magnetic detection element 80b is the first magnetic detection element 80b. It arrange | positions so that it may face the 2nd magnetization band 90b.

  However, in the rotation detection device 300 according to the present embodiment, the first magnetization band 90a and the second magnetization band 90b are arranged so that different magnetic poles face each other. That is, the magnetic poles of the first magnetic band 90 a and the second magnetic band 90 b are formed so as to be shifted by 2π / 2 periods in the rotation direction of the rotor 70.

  The first and second magnetic detection elements 80 a and 80 b are arranged on a straight line along the radial direction of the rotor 70. For this reason, as shown in FIG. 6A, an electrical signal having a phase shifted by 2π / 2 periods, that is, an opposite phase is output from the first magnetic detection element 80a and the second magnetic detection element 80b.

  Here, in the present embodiment, the signal processing circuit includes a differential amplifier circuit that differentially amplifies electrical signals output from the first magnetic detection element 80a and the second magnetic detection element 80b and having opposite phases to each other. ing. Therefore, by differentially amplifying the antiphase electric signals output from the first and second magnetic detection elements 80a and 80b in the differential amplifier circuit, as shown in FIG. Can be amplified. By increasing the amplitude of the output waveform, the detection accuracy of the rotation detection device 300 can be improved because it is less susceptible to noise.

  Also in this embodiment, as in the first embodiment, the signal processing circuit is turned on when the output waveform of the electrical signal output from each of the magnetic detection elements 80a and 80b exceeds a predetermined threshold value Vt. A waveform shaping circuit that generates a pulse signal and a pulse signal integration circuit that integrates the waveform-shaped pulse signals. Also in this case, since the detection resolution is improved, the detection accuracy of the rotation detection device 300 can be improved.

It is a figure for demonstrating the rotation detection apparatus 100 in 1st Embodiment, Comprising: (a) is a front view which shows schematic structure of the rotation detection apparatus 100, (b) is a sectional side view of the rotation detection apparatus 100. is there. It is a graph which shows the conceptual waveform of the electrical signal output with rotation of the rotor 10, Comprising: (a) is a graph which shows the waveform of the electrical signal output from the magnetic detection element 20a, (b) is. It is a graph which shows the waveform of the electric signal output from the magnetic detection element 20b, (c) is a graph which shows the waveform of the electric signal output from the magnetic detection element 20c. (A)-(c) is a graph which shows the waveform at the time of converting the waveform of the electric signal of Drawing 2 (a)-(c) into a pulse signal, respectively, (d) is (a)-(c) It is a graph which shows the waveform which integrated the waveform of (). It is a figure for demonstrating the rotation detection apparatus 200 in 2nd Embodiment, Comprising: (a) is a front view which shows schematic structure of the rotation detection apparatus 200, (b) is a sectional side view of the rotation detection apparatus 200. is there. It is a front view of the rotation detection apparatus 300 for demonstrating the rotation detection apparatus 300 in 3rd Embodiment. (A) is a graph which shows the waveform of the electric signal output from magnetic detection element 80a, 80b with rotation of the rotor 70, (b) is a difference between the electric signal output from magnetic detection element 80a, 80b. It is a graph which shows the waveform which carried out dynamic amplification.

Explanation of symbols

10, 40, 70 Rotors 20a, 50a, 80a First magnetic detection elements 20b, 50b, 80b Second magnetic detection element 20c Third magnetic detection elements 30a, 60a, 90a First magnetization bands 30b, 60b, 90b Second magnetization band 100, 200, 300 Rotation detection device

Claims (5)

A substantially disk-shaped rotor provided rotatably, having a magnetized band in which N and S poles are alternately magnetized so as to form a ring shape as a whole;
A rotation detecting device provided with a magnetic detection element arranged facing the magnetization band and converting a direction change of a magnetic field generated by the magnetization band along with rotation of the rotor into an electric signal and outputting the electric signal. There,
As the magnetization band, first and second magnetization bands are provided in the rotor, the center positions of the first and second magnetization bands coincide with the rotation axis of the rotor, and the first and second magnetization bands The positions of the S pole and the N pole in the magnetization band of 2 are shifted by a predetermined angle in the rotation direction of the rotor;
The magnetic detection element includes a first magnetic detection element disposed so as to face the first magnetization band, and a second magnetic detection element disposed so as to face the second magnetization band. A rotation detection device comprising:   An electric signal in which a phase difference output from the first magnetic detection element and the second magnetic detection element is generated due to an angular shift between the S pole and the N pole in the first and second magnetization bands. The rotation detection device according to claim 1, further comprising: a signal processing circuit that shapes the output waveforms of the first and second waveforms into pulse signals and integrates the shaped pulse signals.   The first magnetization band and the second magnetization band are provided so as to be adjacent to each other in the rotor, and are arranged so as to face a boundary line between the first and second magnetization bands. The third magnetic detection element has a detection axis in the radial direction of the rotor so as to straddle the first magnetization band and the second magnetization band. 3. The rotation according to claim 1, wherein the rotation converts the direction change of the magnetic field generated between the first magnetization band and the second magnetization band into an electric signal and outputs the electric signal. Detection device.   The signal processing circuit shapes the electric signal output from the third magnetic detection element into a pulse signal and integrates it with the pulse signal generated from the electric signals of the first and second magnetic detection elements. The rotation detection device according to claim 3, wherein The first and second magnetized bands are formed so as to be opposed to each other by different magnetic poles, so that they are deviated by a predetermined angle in the rotation direction of the rotor,
2. The differential amplifying circuit for differentially amplifying an output of an electric signal in which the direction change of the magnetic field of the first magnetic detection element and the second magnetic detection element is in opposite phase. Rotation detection device.

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