JP2021021706A - Rotation detection device - Google Patents

Abstract

To provide a rotation detection device having relatively simple structure and capable of accurately detecting the direction of rotation and the number of revolutions.SOLUTION: A rotation detection device detecting the rotation of a rotary member 10 comprises a first magnetic sensor 20 and a second magnetic sensor 30 each of which has a magnetic element expressing a large Barkhausen jump and a coil, the rotary member comprises only two magnetic field generating units 40, 50 having different magnetic field strength. When the rotary member rotates, a circle is drawn by the magnetic field generating units and a magnetic field from a single magnetic pole unit of the magnetic field generating units is detected by both magnetic sensors, the two magnetic sensors are arranged in such a manner that these sensors are respectively parallel to a first and a second tangential line of the circle which are coaxial with the drawn circle, each of a first contact point on the first tangential line and a second contact point on the second tangential line forms a certain phase angle of approximately 180 degrees with respect to a revolving shaft 10a of the rotary member, each of the two magnetic sensors faces the first and second contact points in the normal direction or the direction of the revolving shaft.SELECTED DRAWING: Figure 10

Description

The present invention relates to a rotation detection device that detects the rotation of a rotating member.

A magnetic element that expresses a large Barkhausen jump is described in Patent Document 1 and Patent Document 2. The magnetic element described in Patent Document 1 has a wire shape made of a crystalline metal and is known as a weegand wire. The magnetic element described in Patent Document 2 has a wire shape or a ribbon shape made of a non-crystalline metal.

Patent Documents 3 to 6 describe techniques in which a magnetic element exhibiting a large Barkhausen jump is used for rotation detection. In Patent Document 3, a magnetic flux line extending radially from the center of a single magnetic pole surface of one magnet is detected by one magnetic element. According to Patent Document 4, one magnetic element, one exciter magnet, and an additional sensor element (for example, a Hall element) for identifying forward / reverse rotation are provided. According to Patent Document 5, the magnetic domain direction of the magnetic element is identified by the exciting function of passing an electric current through the coil wound around the magnetic element, and correction is performed. According to Patent Document 6, three magnetic detectors consisting of a magnetic element and a coil, and four magnetic generators for applying an alternating magnetic field of two cycles in one rotation are provided.

Japanese Unexamined Patent Publication No. 53-137641 Japanese Unexamined Patent Publication No. 5-195170 Japanese Unexamined Patent Publication No. 2000-161989 Japanese Patent No. 4712390 Japanese Unexamined Patent Publication No. 2012-225917 Japanese Patent No. 5511748

According to the prior art, there are cases where the rotation speed cannot be accurately detected even if the rotation direction can be detected. Alternatively, even if the rotation direction and the rotation speed can be detected, the structure becomes complicated because the number of parts is relatively large and the power must be supplied to the elements (Hall elements, excitation function) necessary for identification. There is a problem.

An object of the present invention is to provide a rotation detection device having a relatively simple structure capable of accurately detecting the rotation direction and the rotation speed.

In order to achieve the above object, the rotation detection device for detecting the rotation of a rotating member according to the present invention has a slender magnetic element that exhibits a large bulk Hausen jump and a coil wound around the magnetic element. It includes one magnetic sensor and a second magnetic sensor. The rotating member is provided with only two magnetic field generating portions having different magnetic field strengths, and when the rotating member rotates, a circle is drawn by the two magnetic field generating portions, and only the two magnetic field generating portions are formed. The magnetic field from the single magnetic pole portion of is detected by the first magnetic sensor and the second magnetic sensor. The first magnetic sensor and the second magnetic sensor are arranged so as to be parallel to the first tangent line and the second tangent line of the circle coaxial with the circle, respectively, and the first contact line and the second tangent line on the first tangent line are arranged. The second contact on the tangent line forms a phase angle of approximately 180 degrees with respect to the rotation axis of the rotating member. The first magnetic sensor and the second magnetic sensor face the first contact and the second contact, respectively, in the normal direction or the rotation axis direction.

According to the present invention, there is provided a rotation detection device having a relatively simple structure capable of accurately detecting the rotation direction and the rotation speed.

(A) It is a perspective view of the rotation detection apparatus based on 1st Embodiment. (B) It is a top view of the rotation detection device based on the first embodiment. (A) It is a top view when the rotating member is in the 0 degree position. (B) It is a top view when the rotating member is at a 90 degree position. (C) It is a top view when the rotating member is in a position of 180 degrees. (D) is a top view when the rotating member is at the 270 degree position. It is explanatory drawing which shows the relationship between the rotation position and a magnetic field at the time of right rotation. It is explanatory drawing which shows the relationship between the rotation position and a magnetic field at the time of counterclockwise rotation. It is explanatory drawing which superposed FIG. 3 and FIG. (A) It is a perspective view of the rotation detection apparatus based on 2nd Embodiment. (B) It is a top view of the rotation detection device based on the second embodiment. It is explanatory drawing which shows the relationship between the rotation position and a magnetic field at the time of right rotation. It is explanatory drawing which shows the relationship between the rotation position and a magnetic field at the time of counterclockwise rotation. It is explanatory drawing which shows the position of a pulse signal in a rotating coordinate. (A) It is a perspective view of the rotation detection apparatus based on 3rd Embodiment. (B) It is a top view of the rotation detection device based on the third embodiment. It is explanatory drawing which shows the relationship between the rotation position and a magnetic field at the time of right rotation. It is explanatory drawing which shows the relationship between the rotation position and a magnetic field at the time of counterclockwise rotation. It is explanatory drawing which shows the position of a pulse signal in a rotating coordinate. (A) It is a perspective view of the rotation detection apparatus based on 4th Embodiment. (B) It is a top view of the rotation detection device based on the 4th embodiment. It is explanatory drawing which shows the position, the reference position, and the region of a pulse signal in a rotating coordinate. (A) It is a perspective view of the rotation detection apparatus based on 5th Embodiment. (B) It is a top view of the rotation detection device based on the fifth embodiment. It is explanatory drawing which shows the modification of 5th Embodiment. It is explanatory drawing which shows the modification of 5th Embodiment. (A) It is explanatory drawing which shows the modification of 5th Embodiment. (B) It is explanatory drawing which shows the modification of 5th Embodiment. (A) It is a perspective view of the rotation detection apparatus based on 6th Embodiment. (B) It is a top view of the rotation detection device based on the sixth embodiment. It is explanatory drawing which shows the modification of 6th Embodiment. It is explanatory drawing which shows the modification of 6th Embodiment. It is explanatory drawing which shows the modification of 6th Embodiment. (A) It is explanatory drawing which shows the modification of 6th Embodiment. (B) It is explanatory drawing which shows the modification of 6th Embodiment. It is explanatory drawing which shows the other embodiment of a magnetic sensor.

Hereinafter, the present invention will be described based on the illustrated embodiment. However, the present invention is not limited to the embodiments described below. First, the inventor of the present invention diligently studied the first and second embodiments described below.

[First Embodiment]
In FIG. 1, the disk-shaped rotating member 10 rotates in the circumferential direction with reference to a rotating shaft 10a that passes through the center of the rotating member 10 and extends in the thickness direction of the rotating member 10. A magnet 40 is provided on the outer peripheral portion of the rotating member 10. When the rotating member 10 rotates, the magnet 40 draws a circle 11. As an example, the magnet 40 has a substantially cylindrical shape, and is magnetized in the axial direction of the substantially cylindrical shape. The axial direction of the magnet 40, that is, the magnetizing direction is parallel to the rotation axis 10a. In the magnet 40, the north pole faces upward in the rotation axis direction, and the south pole faces downward in the rotation axis direction.

A magnetic sensor 20 is arranged above the rotating member 10 in the direction of the rotation axis. The magnetic sensor 20 is provided in a rotation detection device that detects the rotation of the rotating member 10, and includes an elongated magnetic element 21 that exhibits a large Barkhausen jump and a coil 22 wound around the magnetic element 21. ..

The magnetic element 21 may be, for example, a wire shape, a ribbon shape, or a film-forming type, but is not limited to these, and may be a magnetic material that exhibits a large bulk Hausen jump. The longitudinal direction of the magnetic element 21 can be the direction in which magnetic anisotropy is easily magnetized. The magnetic element 21 includes a core portion and a skin portion provided so as to surround the core portion. As an example, the core portion is a soft layer in which the magnetization direction is inverted even in a weak magnetic field, and the epidermis portion is a hard layer in which the magnetization direction is not inverted unless a strong magnetic field is applied. A pulse signal is induced in the coil 22 when a large Barkhausen jump occurs in the magnetic element 21.

The rotation detection device described above also includes a circuit (not shown) that is connected to the coil 22 and processes a signal generated in the coil 22.

The magnetic sensor 20 is arranged parallel to the tangent line 20a at a certain contact on the circle 11 and above the rotation axis of the contact. Further, the center of the magnetic element 21 in the longitudinal direction is located at a distance above the rotation axis from the contact point. That is, the magnetic sensor 20 is on the circle 13 coaxial with the circle 11 drawn by the magnet.

Regarding the longitudinal direction of the magnetic element 21, the left direction of the paper surface in FIG. 1B is referred to as a minus direction, and the right direction of the paper surface is referred to as a plus direction. When the magnetization directions of the hard layer and the soft layer are the same (for example, the minus direction), the external magnetic field strength in the direction opposite to that direction (for example, the plus direction) increases and the magnetization direction of the soft layer is reversed. When the magnetic field strength is reached, the magnetization direction of the soft layer is reversed. At this time, a large Barkhausen jump occurs, and a pulse signal is induced in the coil wound around the magnetic element. The magnetic field strength when the magnetization direction of the soft layer is reversed is called "operating magnetic field".

When the above-mentioned external magnetic field strength is further increased and the magnetic field strength at which the magnetization direction of the hard layer is reversed is reached, the magnetization direction of the hard layer is also reversed. The magnetic field strength when the magnetization direction of the hard layer is reversed is called "stabilized magnetic field".

In order for the large Barkhausen jump to occur, it is necessary that the magnetization directions of only the soft layer are reversed on the premise that the magnetization directions of the hard layer and the soft layer are the same. In a state where the magnetization directions of the hard layer and the soft layer do not form a single magnetic domain, even if the magnetization of only the soft layer is inverted, no pulse signal is generated, or even if it is generated, the pulse signal is very small. It is difficult to use for rotation detection.

FIG. 2 shows the positional relationship between the magnet 40 and the magnetic sensor 20 as the rotating member rotates. The direction of the magnetic flux line leaking from the N pole surface of the magnet 40 is indicated by an arrow 41. The magnetic flux line 41 leaking from the magnet 40 extends radially from the center of the single magnetic pole surface of the magnet 40. The gradation of the arrow 41 represents the magnetic flux density, and the darker the gradation, the higher the magnetic flux density. FIG. (A) shows a state in which the center of the magnet 40 and the center of the magnetic element 21 face each other in the direction of the rotation axis. This state is called the 0 degree position. The states in which the rotating member 10 is rotated 90 degrees, 180 degrees, and 270 degrees clockwise from the 0 degree position are shown in FIGS. (B), (C), and (D), respectively. .. The magnetic field Ha applied in the longitudinal direction of the magnetic element changes according to the rotation of the rotating member 10.

FIG. 3 shows the relationship between the rotation position when the rotating member 10 is rotated clockwise and the magnetic field Ha. The magnetic field H is positive in the positive direction. In both figures, H ₁ is an operating magnetic field in which the magnetization direction of the soft layer is reversed from the minus direction to the plus direction, and H ₂ is a stabilizing magnetic field in which the magnetization direction of the hard layer is reversed from the minus direction to the plus direction. Is. Further, -H ₁ is an operating magnetic field in which the magnetization direction of the soft layer is reversed from the plus direction to the minus direction, and -H ₂ is a stabilizing magnetic field in which the magnetization direction of the hard layer is reversed from the plus direction to the minus direction. Is.

At the 0 degree position, a magnetic flux line 41 having a strong magnetic field strength is applied to the central portion of the magnetic element 21. When the magnetic element 21 is divided in half with respect to the longitudinal direction, the portion on the minus direction side has the magnetization directions of both the soft layer and the hard layer aligned in the minus direction. In the portion of the magnetic element 21 on the positive direction side, the magnetization directions of both the soft layer and the hard layer are aligned in the positive direction.

When the rotating member 10 rotates clockwise to a position of about 50 degrees, the entire magnetic element 21 is magnetized in the negative direction. This state is indicated by reference numeral As in FIG.

When the rotating member 10 further rotates clockwise, it passes through the 90-degree position shown in FIG. 2 (B) and becomes the 180-degree position shown in FIG. 2 (C). At this 180 degree position, magnetic flux lines in the positive and negative directions are applied to the magnetic element 21, but since the magnetic field strength is very weak, the magnetic element 21 remains magnetized in the negative direction as a whole.

When the rotating member 10 further rotates clockwise and reaches a position of about 240 degrees, the magnetic field Ha reaches the operating magnetic field H ₁ , and the magnetization direction of the soft layer is reversed from the minus direction to the plus direction. At this time, a large Barkhausen jump appears, and a positive pulse signal A is induced in the coil 22. Since this positive pulse signal is a signal indicating that it is rotating clockwise, this positive pulse signal is also called a clockwise rotation signal.

When the rotating member 10 further rotates clockwise and reaches a position of about 310 degrees, the magnetic field Ha reaches the stabilized magnetic field H ₂ . At this time, the magnetization direction of the hard layer is reversed from the minus direction to the plus direction. That is, the magnetic element 21 is magnetized in the positive direction as a whole.

From the position of about 310 degrees to the position of 0 degrees when the rotating member 10 is further rotated clockwise, (1) the hard layer is magnetized in the positive direction and the soft layer is magnetized in the negative direction in the magnetic element 21. The portion and (2) the portion where both the soft layer and the hard layer are magnetized in the negative direction coexist.

When the part (1) above occurs, a large Barkhausen jump is expressed and a negative pulse signal A'is generated. However, since the portion (1) is only a part of the axial length of the magnetic element 21, the noise level of the negative pulse signal A'is extremely small. The negative pulse signal A'is not shown in FIG. 3 because it can be excluded from the detection target by setting the threshold value.

FIG. 4 shows the relationship between the rotation position and the magnetic field Ha when the rotating member 10 rotates counterclockwise. A phenomenon opposite to the case of clockwise rotation described with reference to FIG. 3 occurs in counterclockwise rotation. The rotation angle when rotating counterclockwise is represented by a negative value. That is, the rotating member 10 is from the 0 degree position shown in FIG. 2 (A) to the -90 degree position shown in FIG. 2 (D), the -180 degree position shown in FIG. 2 (C), and FIG. 2 (B). After passing through the -270 degree position shown in the above in order, it finally rotates counterclockwise to the 0 degree position.

First, the entire magnetic element 21 is magnetized in the positive direction at a position of about −50 degrees. This state is indicated by the symbol Cs. At a position of about -240 degrees, the magnetic field Ha reaches -H ₁ . At this time, the magnetization direction of only the soft layer is reversed in the negative direction, and a large Barkhausen jump occurs. Then, a negative pulse signal C is induced in the coil 22. Since this negative pulse signal is a signal indicating that it is rotating counterclockwise, this negative pulse signal is also called a counterclockwise rotation signal. This negative pulse signal (left rotation signal) C has the same magnitude as the right rotation signal A.

The rotating member 10 further rotates counterclockwise, and a positive pulse signal C'is generated between the approximately -310 degree position and the 0 degree position. This positive pulse signal C'has the same magnitude as the negative pulse signal A'during clockwise rotation. Like the negative pulse signal A', the positive pulse signal C'can be excluded from the detection target by setting the threshold value, and is not shown in FIG.

FIG. 5 shows the relationship between the rotation position of the rotating member 10 and the magnetic field Ha for both clockwise rotation and counterclockwise rotation. At the position of about 50 degrees when rotating clockwise, the entire magnetic element 21 is magnetized in the negative direction (reference numeral As), and a large positive pulse signal A is generated in the coil 22 at the position of about 240 degrees. Further, at the position of about -50 degrees when rotating counterclockwise, the entire magnetic element 21 is magnetized in the positive direction (reference numeral Cs), and a large negative pulse signal C is generated in the coil at the position of about −240 degrees.

According to the configuration shown in FIG. 1, the leakage magnetic field passes through the stretching direction of the magnetic element due to the circular motion of the magnet. Therefore, the magnetic element exhibits a large Barkhausen phenomenon, and it is possible to distinguish whether the rotation direction is clockwise or counterclockwise from the signal generated in the coil. The specific values of the angles shown so far are examples, and differ depending on the features of the magnetic element. The angles described below are similar and are not limited.

As shown in FIG. 5, when the rotating member rotates clockwise from the 0 degree position to the approximately 240 degree position, a pulse signal A which is a right rotation signal is generated. Further clockwise rotation progresses to a position of about 310 degrees, and both the soft layer and the hard layer are magnetized in the positive direction. After that, when the rotating member turns counterclockwise, the pulse signal C, which is a counterclockwise rotation signal, is output at a position of about −240 degrees.

On the other hand, it may turn counterclockwise immediately after the pulse signal A is generated at a position of about 240 degrees during clockwise rotation. In this case, since the position does not pass about 310 degrees, the magnetization directions of the soft layer and the hard layer do not match. In this state, the pulse signal C does not occur even if the position is set to -240 degrees by rotating counterclockwise, or even if it occurs, it is very small.

When the position is rotated clockwise from the 0 degree position to the position of about 240 degrees, and then the position is rotated counterclockwise from the position of about 240 degrees to the position of 0 degrees, the actual rotation speed is 0, but the rotation speed in the rotation detection device. Is detected as 1. That is, the rotation speed is not detected accurately. This is because a sufficiently large right rotation signal A is generated, but a sufficiently large left rotation signal C is not generated. If there are n reciprocating movements that rotate clockwise from the 0 degree position to the position of about 240 degrees and then rotate counterclockwise from the position of about 240 degrees to the 0 degree position, the actual number of rotations is 0, but the rotation occurs. In the detection device, the rotation speed is detected as n. As described above, according to the configuration shown in FIG. 1, the rotation speed may not be detected accurately.

[Second Embodiment]
FIG. 6 shows the present embodiment. In addition to the configuration of FIG. 1, a magnetic sensor 30 is provided. The magnetic sensor 20 is called a first magnetic sensor, and the magnetic sensor 30 is called a second magnetic sensor. Like the first magnetic sensor 20, the second magnetic sensor 30 includes an elongated magnetic element 31 that exhibits a large bulk Hausen jump, and a coil 32 wound around the magnetic element 31. Hereinafter, the tangent line 20a is referred to as a first tangent line 20a, and the contact point is referred to as a first contact point.

The second magnetic sensor 30 is arranged parallel to the second tangent line 30a at the second contact on the circle 13 and above the rotation axis of the contact. Further, the center of the magnetic element 31 in the longitudinal direction is located at an interval above the rotation axis from the second contact point. The first contact and the second contact form 180 degrees with respect to the rotation axis 10a. The first magnetic sensor 20 and the second magnetic sensor 30 are on the same plane perpendicular to the rotation axis 10a.

FIG. 7 shows the relationship between the rotation position during clockwise rotation and the magnetic field Ha and the magnetic field Hb applied in the longitudinal direction of the magnetic element 31. Further, FIG. 8 shows the relationship between the rotation position during counterclockwise rotation and the magnetic fields Ha and Hb. In both figures, the solid line shows the change in the magnetic field Ha, and the broken line shows the change in the magnetic field Hb.

When the rotating member 10 rotates clockwise to a position of about 230 degrees, the entire magnetic element 31 is magnetized in the negative direction. This state is indicated by reference numeral Bs in FIG. When the rotating member 10 is further rotated clockwise to a position of about 60 degrees, the magnetization direction of the soft layer of the magnetic element 31 is reversed, and a positive pulse signal (right rotation signal) B is generated in the coil 32.

When the rotating member 10 rotates counterclockwise to a position of about −230 degrees, the entire magnetic element 31 is magnetized in the positive direction. This state is indicated by reference numeral Ds in FIG. When the rotating member 10 further rotates counterclockwise to a position of about -60 degrees, the magnetization direction of the soft layer of the magnetic element 31 is reversed, and a negative pulse signal (counterclockwise rotation signal) D is generated in the coil 32.

As described above, the two magnetic sensors 20 and 30 are provided at positions 180 degrees with respect to the rotation axis. Therefore, as the rotating member rotates, an alternating magnetic field whose phase is 180 degrees out of phase with each other is applied to both magnetic sensors, and the pulse signals output from both magnetic sensors are also 180 degrees out of phase. Therefore, four types of signals, that is, right rotation signals A and B and left rotation signals C and D, can be obtained and the rotation direction can be identified. However, there are cases where the rotation speed cannot be detected accurately. This will be described below.

FIG. 9 is a diagram in which the clockwise rotation shown in FIG. 7 and the counterclockwise rotation shown in FIG. 8 are superimposed and replaced with rotating coordinates. After the signal A is output at the position of about 240 degrees when rotating clockwise, the next signal B is output when the signal A is further rotated 180 degrees clockwise to reach the 60 degree position as shown by reference numeral R.

However, if the signal A is output at the position of about 240 degrees when rotating clockwise and the signal A is rotated counterclockwise as shown by the reference numeral L in FIG. 9, the signal C is output even when the position of about −240 degrees is reached. Even if it is not output or is output, the size is small and it is difficult to detect. This is because the position does not pass about -50 degrees when rotating clockwise. As the counterclockwise rotation progresses further, a signal D is generated at a position of about -60 degrees. As a result, it becomes −180 ° −α from the counterclockwise rotation at the position of about 240 degrees until the counterclockwise rotation signal is output. The sum of the absolute values is 360 ° + α. α is 120 ° as an example. That is, the rotation speed cannot be accurately detected by the same phenomenon as in Patent Document 4.

Here, “−180 ° −α” is the angle drawn by the locus L in FIG. “360 ° + α” is the sum of the angles drawn by the loci L and R in FIG. In the example of FIG. 9, the next signal B is output when the right rotation is continued for 180 degrees along the locus R from the 240 degree position. On the other hand, when the position is changed from the 240 degree position to the left rotation, the next signal D is output when the left rotation is performed by 300 degrees along the locus L. That is, there is a difference of 180 + 300 = 480 degrees between the signal B and the signal D.

As a rotation detection device for a multi-rotation encoder, the detection range from the final pulse needs to be less than 360 degrees in order to prevent the count leakage of the rotation amount from occurring. However, in the above example, since it is 480 degrees, a count omission occurs.

When the detection range from the final pulse exceeds 360 degrees as in this example, it comes to the position of Cs (-50 degree position) in FIG. 9 by rotating clockwise from the position of signal A (240 degree position). However, even if it comes by turning counterclockwise, the count number does not change and the count is leaked. For example, if the position of 0 ° is the boundary of the rotation speed, the rotation speed must be counted by -1 in the counterclockwise rotation.

[Third Embodiment]
A third embodiment based on the first and second embodiments described so far will be described below. As shown in FIG. 10, a magnet 50 is provided on the outer peripheral portion of the rotating member 10 in addition to the magnet 40. The magnet 40 is called the first magnet 40, and the magnet 50 is called the second magnet 50. Like the first magnet 40, the second magnet 50 is magnetized in the direction of the rotation axis, and the upper part of the rotation axis is the north pole and the lower part of the rotation axis is the south pole. The first magnet 40 and the second magnet 50 are arranged so as to form 180 degrees with respect to the rotation axis 10a. The single magnetic pole surfaces of the first magnet 40 and the second magnet 50 generate magnetic fields having different magnetic field intensities. When the rotating member 10 rotates, the first magnet 40 draws a circle 11, and the second magnet 50 also draws a circle 11.

The different magnetic field intensities of the first magnet 40 and the second magnet 50 will be described. The first magnet 40 is a magnet having a strength capable of applying a stabilized magnetic field equal to or higher than the operating magnetic field to the magnetic sensors 20 and 30. On the other hand, the applied strength of the second magnet 50 to the magnetic sensors 20 and 30 is a magnet having a magnetic field strength equal to or higher than the operating magnetic field and not reaching the stabilized magnetic field.

FIG. 11 shows the relationship between the rotation position during clockwise rotation and the magnetic fields Ha and Hb. Further, FIG. 12 shows the relationship between the rotation position during counterclockwise rotation and the magnetic fields Ha and Hb. In both figures, the magnetic field Ha applied by the first magnet 40 to the first magnetic sensor 20 is shown by a solid line, and the magnetic field Hb applied by the first magnet 40 to the second magnetic sensor 30 is shown by a broken line. Further, the magnetic field Ha applied by the second magnet 50 to the first magnetic sensor 20 is indicated by a alternate long and short dash line, and the magnetic field Hb applied by the second magnet 50 to the second magnetic sensor 30 is indicated by an alternate long and short dash line.

In FIG. 11, a positive pulse signal generated in the first magnetic sensor 20 during clockwise rotation is indicated by reference numeral A, and a stabilized magnetic field that is a prerequisite for the output of signal A is indicated by reference numeral As. Further, the positive pulse signal generated in the second magnetic sensor 30 is indicated by reference numeral B, and the stabilized magnetic field which is a prerequisite for the output of signal B is indicated by reference numeral Bs.

In FIG. 12, the negative pulse signal generated in the first magnetic sensor 20 when rotating counterclockwise is indicated by the reference numeral C, and the stabilized magnetic field which is the premise of the output of the signal C is indicated by the reference numeral Cs. Further, the negative pulse signal generated in the second magnetic sensor 30 is indicated by the reference numeral D, and the stabilized magnetic field which is the premise of the output of the signal D is indicated by the reference numeral Ds.

As shown in FIG. 11, when rotating clockwise, the first magnetic sensor 20 reaches a stabilized magnetic field (reference numeral As) for outputting a signal A at a position of about 50 degrees by the first magnet 40. After that, at a position of about 160 degrees, a signal A is output by applying an operating magnetic field by the magnet 50. After that, the magnetic field of the second magnet 50 continues to affect the first magnetic sensor 20 up to the position of about 200 degrees, but the magnetic field strength is small. Further, after that, the magnetic field strength of the first magnet 40 affects the first magnetic sensor 20.

At the rotation position indicated by reference numeral Z1 in FIG. 11, the operating magnetic field strength at which the signal A is output from the magnet 40 is applied to the magnetic sensor 20, but since the signal has already been output by the magnet 50, it is natural at this position. Not output. Similarly, in the magnetic sensor 30, the magnet 40 reaches a stabilized magnetic field (Bs) that outputs a signal B at a position of about 230 degrees. After that, the signal B is output by applying the operating magnetic field by the magnet 50 at the position of about 340 degrees.

FIG. 13 is a diagram in which FIGS. 11 and 12 are superimposed and replaced with rotating coordinates. After the signal A is output, it rotates clockwise as shown by the symbol R, and it becomes +180 degrees until the next signal B is detected. When the signal A is rotated counterclockwise immediately after being output (reference numeral L in FIG. 13), the next signal is the signal D. Since it has passed through the stabilized magnetic field Ds, this signal D becomes an evaluable pulse signal. As a result, it becomes about −180 ° + α until the counterclockwise rotation signal is output. In this way, the range of positions that can be determined is less than 360 degrees, and the rotation speed can be accurately detected.

The case of clockwise rotation will be described again. The state in which the first magnet 40 is directly below the magnetic sensor 30 and the second magnet 50 is on the opposite side of the center of the rotation axis is defined as the 0 degree rotation position. The magnetic sensors 20 and 30 are in a non-magnetized state.

When it rotates clockwise to the 50 degree rotation position, the magnetic field Hb reaches the stabilized magnetic field as shown by the symbol As, and the sensor 30 is in a positive pulse A set state (a state in which the hard layer and the soft layer are magnetized in the negative direction). )become. The magnet 50 also exerts a magnetic field on the sensor 20, but the applied magnetic field is small and does not reach the stabilized magnetic field. Therefore, the sensor 20 is not in the set state.

When the magnetic sensor 20 is rotated clockwise to a rotation position of about 80 degrees (reference numeral Z2), the applied magnetic field Ha reaches the operating magnetic field due to the approach of the magnet 40. However, since the magnetic sensor 20 is not in the set state, the positive pulse B is not output. Since the positive pulse B is not output, the output pulse from the magnetic sensor 20 is once per rotation. On the other hand, in the magnetic sensor 30, the applied magnetic field gradually decreases because the magnet 40 moves away.

When the magnetic sensor 30 is rotated clockwise to reach the 160-degree rotation position, the positive pulse A is in the set state as described above, so that the positive pulse A is output when the magnet 50 approaches. The magnetic field Ha is maximized by the proximity of the magnet 40 to the magnetic sensor 20.

When the magnetic sensor 20 is rotated clockwise to a 180-degree rotation position, the magnetic sensor 20 is in a state after being given a magnetic field strength equal to or higher than the stabilized magnetic field by the magnet 40. In the magnetic sensor 20, the magnet 40 is located directly below, and the applied magnetic field Ha is zero. In clockwise rotation, the external magnetic field suddenly reverses before and after the 180-degree rotation position, so no pulse is output. Since the magnetic sensor 30 is in a state after the positive pulse A is output by the magnet 50, it is in an unset state and the applied magnetic field Hb is also in a zero state.

When the sensor 20 is rotated clockwise to reach the 230-degree rotation position, the sensor 20 reaches the stabilized magnetic field by the magnet 40, as indicated by the reference numeral Bs. The sensor 20 is in a set state of the positive pulse B (a state in which the hard layer and the soft layer are magnetized in the negative direction). The magnet 50 also exerts a magnetic field on the sensor 30, but the sensor 30 is not in the set state because the applied magnetic field is small and does not reach the stabilized magnetic field.

When the magnetic sensor 30 rotates clockwise to a rotation position of about 260 degrees (reference numeral Z1), the applied magnetic field of the magnetic sensor 30 reaches the operating magnetic field due to the approach of the magnet 40. However, since the magnetic sensor 30 is not in the set state, the positive pulse A is not output. Since the positive pulse A is not output, the output pulse from the magnetic sensor 30 is once per rotation. On the other hand, in the magnetic sensor 20, the magnet 40 moves away, and the applied magnetic field gradually decreases.

When the magnetic sensor 20 is rotated clockwise to reach the 340 degree rotation position, the positive pulse B is in the set state as described above, so that the positive pulse B is output when the magnet 50 approaches. The magnetic field applied to the magnetic sensor 30 becomes maximum due to the approach of the magnet 40.

When it is rotated clockwise to reach the 0 degree rotation position, the magnetic sensor 30 is in a state after being given a magnetic field strength equal to or higher than the stabilized magnetic field by the magnet 40. Since the magnet 40 is located directly below, the applied magnetic field Hb is in a zero state. Even if the clockwise rotation is continued, the external magnetic field suddenly reverses before and after the 0 degree rotation position, so that the pulse is not output from the magnetic sensor 30. On the other hand, since the magnetic sensor 20 is in the state after the positive pulse B is output by the magnet 50, it is in the unset state and the applied magnetic field is zero.

Subsequently, the case of counterclockwise rotation will be described again. The set state obtained by rotating clockwise so far becomes invalid when rotating counterclockwise.

When it rotates counterclockwise to the -50 degree rotation position, the magnetic field Hb reaches the stabilized magnetic field as indicated by the symbol Cs, and the sensor 30 is in a negative pulse C set state (the hard layer and the soft layer are magnetized in the positive direction). State). The magnet 50 also exerts a magnetic field on the sensor 20, but the applied magnetic field is small and does not reach the stabilized magnetic field. Therefore, the sensor 20 is not in the set state.

When the magnetic sensor 20 rotates counterclockwise to a rotation position of about -80 degrees, the applied magnetic field Ha reaches the operating magnetic field due to the approach of the magnet 40. However, since the magnetic sensor 20 is not in the set state, the negative pulse D is not output. Since no pulse is output here, the output pulse from the magnetic sensor 20 is once per rotation. On the other hand, in the magnetic sensor 30, the applied magnetic field gradually decreases as the magnet 40 moves away.

When the magnetic sensor 30 is rotated counterclockwise to the -160 degree position, the negative pulse C is in the set state, so that the negative pulse C is output when the magnet 50 approaches. In the magnetic sensor 20, the magnetic field applied to the magnetic sensor 20 becomes maximum due to the approach of the magnet 40.

When it is rotated counterclockwise to the −180 degree position, the magnetic sensor 20 is in a state after being given a magnetic field strength equal to or higher than the stabilized magnetic field by the magnet 40. In the magnetic sensor 20, the magnet 40 is located directly below and the applied magnetic field Ha is zero. Even if the counterclockwise rotation is continued, the external magnetic field suddenly reverses before and after the −180 degree position, so that no pulse is output from the magnetic sensor 20. Since the magnetic sensor 30 is in the state after the negative pulse C is output by the magnet 50, it is in the unset state and the applied magnetic field is zero.

When the sensor 20 is rotated counterclockwise to the -230 degree rotation position, the magnetic field Ha reaches the stabilized magnetic field as indicated by the symbol Ds, and the sensor 20 is in a negative pulse D set state (the hard layer and the soft layer are magnetized in the negative direction). State). The magnet 50 also exerts a magnetic field on the sensor 30, but the applied magnetic field is small and does not reach the stabilized magnetic field. Therefore, the sensor 30 is not in the set state.

When the magnetic sensor 30 rotates counterclockwise to a rotation position of about -260 degrees, the applied magnetic field Hb reaches the operating magnetic field due to the approach of the magnet 40. However, since the magnetic sensor 30 is not in the set state, the negative pulse C is not output. Since no pulse is output here, the output pulse from the magnetic sensor 30 is once per rotation. On the other hand, in the magnetic sensor 20, the magnet 40 moves away, and the applied magnetic field gradually decreases.

When the magnetic sensor 20 is rotated counterclockwise to the -340 degree rotation position, the magnetic sensor 20 is in the negative pulse D set state as described above, so that the negative pulse D is output when the magnet 50 approaches. In the magnetic sensor 30, the magnetic field applied to the magnetic sensor 30 becomes maximum due to the approach of the magnet 40.

When it reaches the 0 degree rotation position by rotating counterclockwise, the magnetic sensor 30 is in a state after being given a magnetic field strength equal to or higher than the stabilized magnetic field by the magnet 40. In the magnetic sensor 30, the magnet 40 is located directly below and the applied magnetic field is zero. No pulse is output because the external magnetic field suddenly reverses before and after the 0 degree rotation position. Since the magnetic sensor 20 has output the negative pulse D by the magnet 50, it is in an unset state and a state in which the applied magnetic field is zero.

In this embodiment, a difference in magnetic field strength is provided between the magnet 40 and the magnet 50. The magnet 40 having a large magnetic field strength has a function of applying a stabilized magnetic field. On the other hand, the magnet 50 has a function of applying an operating magnetic field. By dividing the functions in this way, the location where the set state is generated and the location of the pulse output can be set to different positions. By properly arranging the positions and roles, it is possible to prevent the count omission at the time of reversal.

For example, as shown in FIGS. 11 and 12, when rotating clockwise, the order is physically D → As → Ds → A → C → Bs. Here, when the rotation is reversed to the left at the position C between A and Bs, C → A → Ds → As → D, and Ds is always inserted “before D”. As a result, the first D pulse output is guaranteed even in the inversion after the A pulse output.

In this embodiment, the order is as follows. The value in parentheses indicates the change in the number of pulses counted.
Rotate clockwise D → As → Ds → A (+1) → C → Bs → Cs → B (+1) →
Left rotation B → Cs → Bs → C (-1) → A → Ds → As → D (-1) →

In the above, since both the forward and reverse rotation sets always exist between the pulse generation positions (positions of "+1" and "-1"), it does not occur that the pulse immediately after the reverse rotation does not occur.

An even number of magnets (magnetic field generating parts) may be used.

[Fourth Embodiment]
In the third embodiment, the magnetic sensors 20 and 30 and the magnets 40 and 50 face each other in the rotation axis direction, but in the fourth embodiment, the magnetic sensors 20 and 30 and the magnets 40 and 50 are normal. Oppose in the direction. This will be described below with reference to FIG.

The magnets 40 and 50 are all arranged so that the magnetizing direction is the radial direction of the circle 11. The radial outer side is the north pole, and the radial inner side is the south pole. Both magnets form 180 degrees with respect to the axis of rotation 10a.

The first magnetic sensor 20 faces the first contact P1 in the normal direction passing through the first contact P1. Further, the second magnetic sensor 30 faces the second contact P2 in the normal direction passing through the second contact P2. The first contact P1 and the second contact P2 form 180 degrees with respect to the rotation shaft 10a. The first magnetic sensor 20 is arranged parallel to the tangent line passing through the first contact P1, and the second magnetic sensor 30 is arranged parallel to the tangent line passing through the second contact P2. Also in this fourth embodiment, the same signals as those in FIGS. 11 and 12 in the third embodiment can be obtained.

In the third embodiment, since the magnet and the magnetic sensor face each other in the rotation axis direction, the size in the normal direction (diameter direction) can be reduced. In the fourth embodiment, since the magnet and the magnetic sensor face each other in the normal direction, the size in the rotation axis direction can be reduced. In both embodiments, a rotation detection device having a relatively simple structure is realized.

The magnetic sensors 20 and 30 do not have to be on the same circle, and the magnets 40 and 50 do not have to be on the same circle. In the third and fourth embodiments, the arrangement of the magnetic sensors 20 and 30 is the same as long as the rotational movement of the magnets 40 and 50 and the positional relationship of the magnetic sensors 20 and 30 are maintained without departing from the positional relationship of the pulse signals shown in FIG. The arrangement of the magnets 40 and 50 is not limited to the plane and the circumference of the same radius, and the arrangement of the magnets 40 and 50 is not limited to the circumference of the same plane and the same radius. It suffices if the magnet can pass by a rotational motion that draws a tangent line parallel to the center lines 20a and 30a of the magnetic sensor.
Further, although the magnet has a cylindrical shape, other shapes may be used. Further, for ease of explanation, the magnet 50 having a weak magnetic field strength is shown in a columnar shape smaller than the magnet 40, but by changing the material of the magnet and / or the distance between the magnet and the magnetic sensor. Both magnets can have the same shape.

[Fifth Embodiment]
In both the third and fourth embodiments, the two magnetic field generating parts of the rotating member 10 are composed of separate permanent magnets 40 and 50. On the other hand, in the fifth embodiment, at least two magnetic field generating portions are configured by one magnet and a yoke installed in the center of the surface of the rotating member.

As shown in FIG. 16, the magnet 60 is arranged at the center of the surface of the rotating member 10. The magnet 60 has a substantially cylindrical shape, its axis is coaxial with the rotation axis, and is magnetized in the axial direction thereof. A yoke 70 is arranged above the magnet 60 in the direction of the rotation axis. The yoke 70 has a rectangular parallelepiped shape, and is arranged so that its length direction is perpendicular to the rotation axis 10a. Both the center of the magnet 60 and the center of the yoke 70 are located on the rotation axis 10a, but the center is not limited to this.

Both ends 70a and 70b of the yoke 70 in the length direction are two magnetic field generating portions provided on the rotating member 10. Both magnetic field generators form 180 degrees with respect to the rotation axis 10a. When the rotating member 10 rotates, the yoke 70 also rotates, and a circle 11 is drawn by both magnetic field generating portions of the yoke.

The positional relationship between the first magnetic sensor 20 and the second magnetic sensor 30 is the same as that in FIG. 10 in the third embodiment. The first magnetic sensor faces the first contact of the circle 11 in the direction of the rotation axis, and the second magnetic sensor faces the second contact of the circle 11 in the direction of the rotation axis.

The surfaces of both ends of the yoke 70 in the length direction, which are present at two locations facing the magnetic sensor, are attracted by the magnet 60 to form a single polar magnetic surface. Further, different magnetic field strengths can be applied to the magnetic sensors 20 and 30 by changing the shape of both ends of the yoke 70 in the length direction and / or both of the gaps to the magnetic sensor.

In FIG. 16, of the end portions 70a and 70b in the length direction, the thickness of the end portion 70a in the rotation axis direction is larger than the thickness of the end portion 70b in the rotation axis direction. That is, the end portion 70a has a stronger magnetic force than the end portion 70b.

In FIG. 17, at both ends 70c and 70d of the yoke 70 in the length direction, the width of the end 70c is larger than the width of the end 70d. That is, the end portion 70c has a larger magnetic force than the end portion 70d.

In this way, one magnet 60 and the yoke 70 provide a rotation detection device similar to the third and fourth embodiments. According to the present embodiment, there is an advantage that the number of magnets can be reduced as compared with the third and fourth embodiments.

Alternatively, as shown in FIG. 18, the yoke 70 and the magnet 60 may be on the same plane perpendicular to the rotation axis 10a. A hole 71 is provided substantially in the center of the yoke 70, and a ring-shaped magnet 60 is arranged so as to surround the hole 71. Both the center of the ring-shaped magnet 60 and the center of the hole 71 of the yoke 70 are on the rotation shaft 10a. When the yoke 70 rotates, a circle 11 is drawn by the surfaces of both ends in the length direction of the yoke. Such a rotary shaft penetration type, that is, a hollow type is also possible.

As shown in FIG. 19A, both end portions 70e and 70f in the length direction may be formed by bending both ends in the length direction of the yoke 70 downward in the rotation axis direction. The yoke 70 has a substantially U-shape as a whole due to the main body and both ends in the length direction. Then, when the rotating member 10 rotates, the yoke 70 also rotates, and a circle is drawn by both ends 70e and 70f in the length direction. Since both ends have different dimensions in the width direction, the magnetic field strength is also different. The first magnetic sensor 20 and the second magnetic sensor 30 are arranged on the outer side in the radial direction of the circle. That is, the first magnetic sensor 20 faces the corresponding first contact in the normal direction, and the second magnetic sensor 30 faces the corresponding second contact in the normal direction. Both magnetic sensors form 180 degrees with respect to the axis of rotation 10a.

As shown in FIG. 19B, the distances of the yoke 70 at both ends 70g and 70h in the length direction from the rotation axis can be changed. The distance L between the end portion 70g and the rotating shaft is larger than the distance L'between the end portion 70h and the rotating shaft.

[Sixth Embodiment]
In the present embodiment, magnets having a substantially rectangular parallelepiped shape are arranged so that their length directions are perpendicular to the rotation axis, and the surfaces at both ends in the length direction are two magnetic field generating parts. As shown in FIG. 20, a magnet 60 having a substantially rectangular parallelepiped shape is arranged on the surface of the rotating member 10. The magnet 60 is arranged so that the length direction is perpendicular to the rotation axis 10a. The center of the magnet 60 is on the rotation axis 10a. The magnet 60 is magnetized in the thickness direction, that is, in the rotation axis direction.

Both ends 60a and 60b of the magnet 60 in the length direction are two magnetic field generating portions and form 180 degrees with respect to the rotation axis 10a. The thickness of the end portion 60a in the rotation axis direction is smaller than the thickness of the end portion 60b in the rotation axis direction. When the rotating member 10 rotates, a circle 11 is drawn by both ends 60a and 60b of the magnet 60 in the length direction.

The positional relationship between the first magnetic sensor 20 and the second magnetic sensor 30 is the same as in FIG. The first magnetic sensor 20 faces the corresponding first contact in the direction of rotation axis, and the second magnetic sensor 30 faces the corresponding second contact in the direction of rotation axis. The surfaces 60a and 60b at both ends in the length direction in which a magnetic field is applied to the magnetic sensor are both single magnetic pole surfaces. One magnet 60 provides a rotation detection device similar to the third and fourth embodiments. According to the present embodiment, the yoke of the fifth embodiment is unnecessary, and the number of component parts can be reduced. It has the advantage of having a simpler structure.

As shown in FIG. 21, the width of the end portion 60c can be made larger than the width of the end portion 60d with respect to both end portions 60c and 60d of the magnet 60 in the length direction. That is, the end portion 60c has a higher magnetic field strength than the end portion 60d.

As shown in FIG. 22, a hole 61 may be provided at a substantially central portion of the magnet 60 so that the center of the hole is located on the rotation shaft 10a. With this structure, a rotary shaft penetration type, that is, a hollow type is also possible.

As shown in FIG. 23, the center of the rectangular parallelepiped magnet 60 in the length direction may be offset from the rotation axis 10a. The offset amount is indicated by the code OS. As a result, there is a difference in the distance between the two magnetic field generators and the magnetic sensor. This difference causes a difference in the magnetic field strength applied to the magnetic element.

In FIG. 24A, both ends in the length direction of the magnet 60 are bent downward on the rotation axis to form both ends 60e and 60f in the length direction. The width of the end 60e is larger than the width of the end 60f. That is, the end portion 60e has a higher strength than the end portion 60f. The magnet 60 has a substantially U-shape as a whole due to the main body and both ends in the length direction. When the rotating member 10 rotates, a circle 11 is drawn by the surfaces of both ends thereof. The first magnetic sensor 20 faces the first contact on the circle 11 in the normal direction, and the second magnetic sensor 20 faces the second contact on the circle 11 in the normal direction.

In FIG. 24B, the distances from the rotating shaft 10a to both end portions 60e and 60f are different. The distance L from the end 60e to the rotating shaft 10a is larger than the distance L'from the end 60f to the rotating shaft 10a.

[Method of determining the number of rotations and the direction of rotation]
Hereinafter, the method of determining the rotation speed and the rotation direction in the third and fourth embodiments will be described as two continuous signals for easy understanding.

The determination method is performed by a signal processing circuit including a memory. This circuit has an identification function, a reference function, and an arithmetic function. First, the identification function identifies the signals from the two magnetic sensors into four, A, B, C, and D. Next, with the reference function, the previous (last detected) history signal stored in the initial state when counting the number of rotations and the rotation direction and the signal accompanying the subsequent rotation are sequentially stored in the memory. Write. Two consecutive past and present signals stored in the memory are searched in four preset types of coded tables, and matching count values are returned. A search is performed each time a signal is input, and the count value of the result is sequentially added or subtracted by the calculation function. The added / subtracted numerical values represent the number of rotations and the direction of rotation at that time. However, the count value of one non-continuous signal is set to 0. As an example, as shown in FIG. 15, when a reference position is set between the signal B and the signal D, four types of coded patterns are displayed as (code: count), (AB: 0.5) (CB: 0). ) (BC: 0) (DC: −0.5), the rotation direction and the rotation speed can be accurately counted.

[How to synchronize the position within one rotation and the number of rotations]
When the rotation detection device is used for multiple rotations of the motor, the rotation speed is detected by the method described with reference to FIG. 15 during a power failure of the motor drive system, and the displacement angle of the rotation speed counter from the reference position when the system is started. Need to be determined. In this case, the signals A, B, C, and D are regions 3 or 4 in FIG. 15 when the last detected signal is the signal A. Similarly, if the last detection signal is B, it will be region 1 or 2, if the last detection signal is C, it will be region 2 or 3, and if the last detection signal is D, it will be region 1 or 4. .. When the last detection signal is A or C, the rotation speed can be specified because the detection is not in the range across the reference position. However, when the last detection signal is B or D, the detection is in a range that straddles the reference position, so it cannot be determined whether the reference position is at the position from the signal B or the position from the signal D. That is, the number of rotations cannot be specified. Therefore, by externally attaching a one-rotation absolute type position sensor, the relationship with the reference position can be clarified and the rotation speed can be determined.

[Other Examples of Circuit]
The circuit needs to be powered. The rotation detection device of each embodiment uses a magnetic element. Therefore, the output signal from the large Barkhausen jump is an electromotive force as is already known, and can be used as a power source for the circuit. That is, by adding a function of processing the output of the magnetic sensor with a rectifier and a capacitor to the circuit, it is possible to supply electric power to the circuit from the two magnetic sensors. Therefore, for example, it can be applied to battery-less motor multi-rotation encoders. A reed switch is a non-powered sensor that senses a magnetic field, and if a reed switch is used as a position sensor, it is not necessary to use a battery even for meters (flow rate, water supply, air volume, gas). For example, it is not necessary to supply power to applications such as bicycles that do not require position synchronization for one rotation due to the number of rotations of wheels. It is also possible to send data wirelessly using this power.

[Other Examples of Magnetic Sensors]
FIG. 25 shows another embodiment of the first magnetic sensor 20. A coil 22 is wound around a magnetic element 21 that exhibits a large Barkhausen jump, and parts 23a and 23b made of a soft magnetic material are attached to the magnetic element 21 at both ends of the magnetic element. In FIG. 22, both ends of the magnetic element are exposed from the parts made of the soft magnetic material, but they may not be exposed. It is preferable that the parts 23a and 23b of the soft magnetic material are equivalent in terms of material, shape and position. As a component example, a generally commercially available ferrite core for EMS (Electromagnetic Susceptibility) countermeasures can be used. As for the second magnetic sensor 30, the coil 32 is wound around the magnetic element 31, and the soft magnetic material parts 33a and 33b are attached to both ends of the magnetic element. With this soft magnetic member, the demagnetic field generated at the end of the magnetic element is suppressed, and the output signal (electric energy) can be increased. In other words, the wire length of the magnetic element can be shortened, and the magnetic sensor becomes smaller.

Although the reference numerals of the corresponding parts of the embodiment are described for ease of explanation, each configuration is not limited to the configuration of the corresponding parts indicated by the reference numerals.

The following additional notes will be disclosed with respect to the embodiments described so far.

[Appendix 1]
A rotation detection device that detects the rotation of rotating members.
A first magnetic sensor and a second magnetic sensor having an elongated magnetic element that expresses a large bulk Hausen jump and a coil wound around the magnetic element are provided.
The rotating member is provided with only two magnetic field generating portions having different magnetic field strengths, and when the rotating member rotates, a circle is drawn by the two magnetic field generating portions, and only the two magnetic field generating portions are formed. The magnetic field from the single magnetic pole portion of the above is detected by the first magnetic sensor and the second magnetic sensor.
The first magnetic sensor and the second magnetic sensor are arranged so as to be parallel to the first tangent line and the second tangent line of the circle coaxial with the circle, respectively.
The first contact on the first tangent line and the second contact on the second tangent line form a phase angle of approximately 180 degrees with respect to the rotation axis of the rotating member.
The first magnetic sensor and the second magnetic sensor face the first contact and the second contact in the normal direction or the rotation axis direction, respectively.
Rotation detector.

[Appendix 2]
The rotation detection device according to Appendix 1, wherein only the two magnetic field generators are composed of separate permanent magnets.

[Appendix 3]
The rotation according to Appendix 1, wherein only the two magnetic field generating portions are both ends in the length direction of a substantially rectangular parallelepiped yoke provided so as to be in contact with a single magnet provided at the center of the rotating member. Detection device.

[Appendix 4]
The rotation detection device according to Appendix 1, wherein only the two magnetic field generating portions are both ends in the length direction of a substantially rectangular parallelepiped magnet installed so that the length direction is perpendicular to the rotation axis.

[Appendix 5]
It is connected to the first magnetic sensor and the second magnetic sensor, receives a total of four types of signals from the first magnetic sensor and the second magnetic sensor according to the rotation direction of the rotating member, and is based on the signals. The rotation detection device according to any one of Appendix 1 to 4, further comprising a circuit for determining the rotation speed and the rotation direction of the rotating member.

[Appendix 6]
The rotation detection device according to Appendix 5, wherein the circuit operates using the signal as electric power.

[Appendix 7]
With an additional external position sensor
The circuit is connected to the position sensor and corrects the rotation speed and the rotation direction of the rotating member based on the output signal of the position sensor.
The rotation detection device according to Appendix 5 or 6.

[Appendix 8]
The rotation detection device according to any one of Items 1 to 7, wherein the first magnetic sensor and the second magnetic sensor further include soft magnetic members provided at both ends of the magnetic element.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and modifications can be made based on the technical idea of the present invention.

10 Rotating shaft 11 Circle drawn by a magnet or magnetic field source 13 tangent line 13 Circle on which a magnetic sensor is placed 20, 30 Magnetic sensor 21, 31 Magnetic element 22, 32 Coil 23a, 23b, 33a, 33b Soft magnetic member 40, 50, 60 Magnet 41 Magnet magnetic flux wire 70 York

Claims (8)

A rotation detection device that detects the rotation of rotating members.
A first magnetic sensor and a second magnetic sensor having an elongated magnetic element that expresses a large bulk Hausen jump and a coil wound around the magnetic element are provided.
The rotating member is provided with only two magnetic field generating portions having different magnetic field strengths, and when the rotating member rotates, a circle is drawn by the two magnetic field generating portions, and only the two magnetic field generating portions are formed. The magnetic field from the single magnetic pole portion of the above is detected by the first magnetic sensor and the second magnetic sensor.
The first magnetic sensor and the second magnetic sensor are arranged so as to be parallel to the first tangent line and the second tangent line of the circle coaxial with the circle, respectively.
The first contact on the first tangent line and the second contact on the second tangent line form a phase angle of approximately 180 degrees with respect to the rotation axis of the rotating member.
The first magnetic sensor and the second magnetic sensor face the first contact and the second contact in the normal direction or the rotation axis direction, respectively.
Rotation detector. The rotation detection device according to claim 1, wherein only the two magnetic field generators are composed of separate permanent magnets. The first aspect of the present invention, wherein the only two magnetic field generating portions are both ends in the length direction of a substantially rectangular parallelepiped yoke provided so as to be in contact with a single magnet provided at the center of the rotating member. Rotation detector. The rotation detection device according to claim 1, wherein only the two magnetic field generating units are both ends in the length direction of a substantially rectangular parallelepiped magnet installed so that the length direction is perpendicular to the rotation axis. It is connected to the first magnetic sensor and the second magnetic sensor, receives a total of four types of signals from the first magnetic sensor and the second magnetic sensor according to the rotation direction of the rotating member, and is based on the signals. The rotation detection device according to any one of claims 1 to 4, further comprising a circuit for determining the rotation speed and the rotation direction of the rotating member. The rotation detection device according to claim 5, wherein the circuit operates using the signal as electric power. With an additional external position sensor
The circuit is connected to the position sensor and corrects the rotation speed and the rotation direction of the rotating member based on the output signal of the position sensor.
The rotation detection device according to claim 5 or 6. The rotation detection device according to any one of claims 1 to 7, wherein the first magnetic sensor and the second magnetic sensor further include soft magnetic members provided at both ends of the magnetic element.