JP3136921B2 - Magnetic sensor and motor with magnetic sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor and a motor equipped with the magnetic sensor.

[0002]

2. Description of the Related Art In almost all fields such as OA, HA, FA, and audiovisual equipment in recent years, there has been a growing demand for advanced control technology and small, lightweight, thin, and low cost motors. Is coming.

Therefore, there is a demand for smoother and more stable rotation speed control from a low speed to a high speed and a more accurate stop position control for the operation of the motor. To meet these demands, it has become necessary to develop optimal sensors and motors.

A conventional magnetic sensor and a motor equipped with the sensor will be described below. FIG. 13 shows a configuration of a conventional magnetic sensor. In the figure, reference numeral 11 denotes a cylindrical magnetic drum fixed to a shaft 13 and having N and S poles alternately and continuously magnetized at equal intervals on the outer peripheral surface;
Reference numeral 2 denotes a magnetic sensor element such as a ferromagnetic magnetoresistive element which is arranged close to the outer peripheral surface of the magnetic drum 11 and detects a change in the magnetic field of the magnetic drum.

In the conventional sensor, a change in the magnetic field of the magnetic drum 11 which intersects the magnetic sensor element 12 in a direction perpendicular to the magnetic sensor element 12 due to the rotation of the magnetic drum 11 is taken out as a change in the resistance value of the magnetic sensor element 12, and this change in the resistance value is taken as a circuit. By processing, a voltage signal corresponding to the passage of the magnetic pole of the magnetic drum 11 is generated. FIG. 14 shows a voltage signal waveform generated by a conventional sensor. Next, the voltage signal is digitally processed to detect and measure the rotation speed and rotation angle of the magnetic drum 11.

FIG. 15 shows a motor equipped with the conventional magnetic sensor. In the figure, a magnetic drum 11 is attached to a shaft 13 of a motor 14,
The magnetic sensor element 12 is fixed in the state of being close to the outer peripheral surface of the magnetic sensor element 1.

In a motor equipped with a conventional sensor, the magnetic sensor element 12 has two built-in detection patterns, and two output signals φA and φB whose electrical angles are shifted by 90 degrees as shown in FIG. Is obtained. The rotation direction of the motor can be determined from these two output signals. Further, by subjecting the output signal to pulse circuit processing, it is possible to obtain an output signal having four times the resolution.

FIG. 17 shows a control device for controlling the rotation speed and the stop position of the motor based on the output signals shown in FIG. The control method by the control device will be briefly described. The magnetic sensor element 12 detects a change in magnetic flux of the magnetic drum 11 accompanying rotation of the motor 14 as two-phase electric signals φA and φB shown in FIG. The electric signal is signal-processed by the waveform processing circuit 15. The processed signal is fed back to the position control circuit 16 and the speed control circuit 17 and controlled by the system 18.

[0009]

However, in the above-mentioned conventional sensor, the change in the magnetic field is detected at a certain point on the outer periphery of the magnetic drum 11 by the magnetic sensor element 12, so that the change in the magnetic field is detected on the outer peripheral surface of the magnetic drum. The amplitude of the output signal of the magnetic sensor element 12 varies with the rotation state as shown in FIG. 18 due to the variation in the magnetization of the magnetized N-pole and S-pole magnetic patterns and the mounting accuracy of the magnetic drum and the magnetic sensor element. Change. In particular, rotation unevenness was likely to occur every rotation. In addition, there is a problem that not only a difference in the amplitude of the output signal occurs but also the signal accuracy deteriorates.

[0010] In order to solve the above problem, it is possible to reduce the variation in the magnetization of the magnetic drum and adjust the mounting of the magnetic drum and the magnetic sensor element. .

In order to increase the resolution of the output signal, a multi-phase output signal shifted from the basic signal by a certain electrical angle is used. In this case, several magnetic sensor elements are arranged around the magnetic drum. However, it is necessary to perform high-precision adjustment so that an output signal having a predetermined electrical angle is obtained.
It was a manufacturing problem.

For this reason, in a motor equipped with a conventional magnetic sensor, unevenness of rotation occurs in the rotation speed control of the motor due to the poor signal accuracy of the magnetic sensor described above, and the stop position accuracy is also reduced in the stop position control. Had the problem that it became worse.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and is less affected by variations in the mounting of the magnetic drum and the magnetic sensor element and variations in the magnetization of the magnetic pattern of the magnetic drum, and provides a magnetic signal with a high signal accuracy of the output signal. It is intended to provide a sensor. Further, it is another object of the present invention to provide a motor capable of performing a rotation speed control with less rotation unevenness or a stop position control with a good stop position accuracy by mounting the present magnetic sensor on the motor.

[0014]

In order to achieve this object, the present invention provides a magnetic structure in which N poles and S poles are alternately and continuously magnetized at equal intervals, and one of the magnetic structures. A plurality of pole teeth facing the magnetic poles, a main magnetic pole for converging a magnetic flux generated in the plurality of pole teeth, and first and second magnetic bodies arranged in parallel with each other; A magnetoelectric converter disposed between the main magnetic poles facing the second magnetic body and converting a change in transmitted magnetic flux into an electric signal, wherein each of the first and second magnetic bodies has a respective pole tooth. In addition to displacing the two opposing magnetic poles of the magnetic structure so as to face each other,
A position or a speed of the magnetic structure is detected by using a magnetic sensor capable of relatively moving the magnetic structure and the first and second magnetic bodies in a direction in which the magnetic poles of the magnetic structure are arranged.

Further, in the present invention, the above-mentioned magnetic sensor is mounted on a motor to control the driving of the motor.

[0016]

In the above construction, one of the N-pole and S-pole magnetized on the magnetic structure is simultaneously detected from a plurality of locations by a plurality of pole teeth provided on the first and second magnetic bodies. I do. Next, the magnetic flux detected by the pole teeth is converged by the main magnetic pole, and a change in magnetic flux passing through the first and second magnetic bodies is detected by the magnetoelectric converter as an output signal. An output signal with a small amplitude difference and high signal accuracy obtained by the magnetic sensor is used for motor control.

[0017]

【Example】

Embodiment 1 Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing the appearance of a motor on which a magnetic sensor according to the present invention is mounted, wherein A is a sensor section.

In FIG. 1, reference numeral 1 denotes a magnetic structure fixed coaxially with the shaft 3 of the motor 4 and having N and S magnetic poles alternately and continuously magnetized at equal intervals on the outer peripheral surface. This is a cylindrical magnetic drum.

Reference numeral 9 denotes a first magnetic body having a plurality of pole teeth at the tip end facing one of the magnetic poles of the magnetic drum 1 and a main pole for converging a magnetic flux generated at the plurality of pole teeth. .
The second magnetic body 10 has the same structure as the first magnetic body 9, and the magnetic drum 1 with the pole teeth of the first magnetic body 9 facing each other.
Are arranged in parallel with the first magnetic body 9 in such a positional relationship as to face a magnetic pole opposite to the magnetic pole of the first magnetic body 9. For example, when the first magnetic body 9 faces the north pole of the magnetic drum 1, the second magnetic body 10 is arranged in a positional relationship facing the south pole.

First sensor core 5 and second sensor core 6
Has a plurality of first and second magnetic bodies 9, 10 arranged at equal intervals and coupled in a ring shape. A ball element 7, which is one of the magnetoelectric converters, is disposed between a first magnetic body 9 and a second magnetic body 10, and is provided between the first magnetic body 9 and the second magnetic body 10. The change in magnetic flux of

The operation of the magnetic sensor A configured as described above and the motor on which the sensor is mounted will be described with reference to FIGS. Note that N and S shown in the figure indicate magnetic poles.

FIG. 2 shows the magnetic sensor A of the present invention shown in FIG.
FIG. 2 is a view of the arrangement of the first magnetic body 9 and the second magnetic body 10 with respect to the magnetic drum 1 in FIG. For convenience of explanation, a magnetic pole magnetized on the outer periphery of the magnetic drum 1 and a plurality of pole teeth of the first and second magnetic bodies 9 and 10 facing the magnetic pole are linearly shown. The plurality of pole teeth provided on the first magnetic body 9 and the second magnetic body 1
The plurality of pole teeth provided on the magnetic drum 1
In FIG. 2, when a plurality of pole teeth provided on the first magnetic body 9 face the N pole, A plurality of pole teeth provided on the two magnetic bodies 10 are provided so as to face the S pole. Here, 7 is a hall element.

FIG. 3 shows this state as viewed from the direction of arrow C in FIG. In the state shown in FIGS. 2 and 3, the magnetic field between the first magnetic body 9 and the second magnetic body 10 is the magnetic drum 1 and the first and second magnetic bodies as indicated by arrows in FIG. And the magnetic field from the first magnetic body 9 to the second magnetic body 10, and the Hall element 7 detects the magnetic field from the first magnetic body 9 to the second magnetic body 10.

Next, the magnetic drum 1 moves from the state shown in FIG. 2 so that the plurality of pole teeth provided on the first magnetic body 9 face the south pole and the plurality of pole teeth provided on the second magnetic body 10. The first magnetic body 9 with respect to the magnetic drum 1 when the pole teeth of
FIG. 5 is a view of the arrangement position of the second magnetic body 10 and the second magnetic body 10 viewed from the direction of arrow B in FIG. 1, and FIG. 6 is a view of this state viewed from the direction of arrow D in FIG.

When the state shown in FIGS. 5 and 6 is reached, the magnetic field between the first magnetic body 9 and the second magnetic body 10 is, as shown by the arrow in FIG. Second magnetic body 9,
10 and a magnetic field directed from the second magnetic body 10 to the first magnetic body 9, and the Hall element 7 becomes the second magnetic body 1.
A magnetic field from 0 to the first magnetic body 9 is detected. Thus, the rotation of the magnetic drum 1 causes the magnetic poles of the N pole and the S pole to alternately face the plurality of pole teeth of the first magnetic body 9 and the second magnetic body 10. Magnetic fields having different directions are alternately applied to the Hall element 7 provided between the second magnetic body 10 and the Hall element 7. The Hall element 7 detects this magnetic field change, converts it into an electric signal, and outputs a sinusoidal output waveform as shown in FIG. The sinusoidal output waveform is a waveform with a small amplitude difference and high signal accuracy.

As described above, in this embodiment, the magnetization of the magnetic drum provided coaxially with the drive shaft of the motor is simultaneously detected from the plurality of pole teeth provided on the first and second magnetic members. And
The convergence by the main magnetic pole reduces the influence of the variation in the mounting of the magnetic drum and the magnetic sensor element and the variation in the magnetization of the magnetic pattern of the magnetic drum as compared with the conventional method of detecting at one point on the outer periphery of the magnetic drum. A large output signal can be obtained, and a magnetic sensor with a small signal amplitude difference and high signal accuracy can be provided.

Furthermore, in the motor equipped with the magnetic sensor according to the present embodiment, a large output signal having a small amplitude difference and a high signal accuracy is used for the control of the motor. It is possible to realize a motor capable of controlling the rotation speed and controlling the stop position with high accuracy. (Embodiment 2) FIG. 9 shows the magnetic flux transmitted from the magnetic drum 1 in FIG. 3 of the embodiment 1 to the first and second magnetic bodies 9, 10. In the figure,

[0029]

(Equation 1)

The magnetic flux from the N pole of the magnetic drum 1 to the pole teeth of the first magnetic body 9 is

[0031]

(Equation 2)

The magnetic flux from the pole teeth of the second magnetic body 10 to the S pole of the magnetic drum 1 is shown. The arrows in the figure indicate the magnetic flux from the north pole to the south pole of the magnetic drum 1.

As shown in the figure, the magnetic drum 1 to the first magnetic body 9
It can be seen that a part of the magnetic flux passing through the pole teeth of the second magnetic body 10 leaks from the N pole of the magnetic drum 1 to the S pole. Due to the influence of the leakage of the magnetic flux, the magnetic flux of the magnetic drum 1 that converges on the pole teeth of the first magnetic body 9 and the second magnetic body 10 is weakened.

Accordingly, the magnetic flux converged by the magnetic sensor A becomes unstable, and as a result, the accuracy of the magnetic sensor deteriorates.

In particular, the smaller the distance between the pole teeth of the first magnetic body 9 and the second magnetic body 10, that is, the smaller the distance between the magnetic poles of the magnetic drum 1, the more the magnetic pole adjacent to one magnetic pole of the magnetic drum 1. And the magnetic flux that the pole teeth converge from one magnetic pole of the magnetic drum 1 is reduced, which affects the accuracy of the magnetic sensor.

In the present embodiment, in order to solve the above-described problem, the magnetic sensor described in the first embodiment has an intermediate portion between the pole teeth of the first magnetic body 9 and a pole of the second magnetic body 10 adjacent thereto. A third magnetic body 8 is disposed so as to connect the intermediate portion between the teeth, and two magnetic poles of the magnetic drum 1 facing each other are magnetically coupled by the third magnetic body 8.

FIG. 10 is a perspective view of the magnetic sensor of the second embodiment in which the third magnetic body 8 is provided between the pole teeth of the first magnetic body 9 and the second magnetic body 10 of the magnetic sensor of the first embodiment. FIG.

FIG. 11 is a diagram showing the state of the magnetic flux transmitted from the magnetic drum to the first, second, and third magnetic members 8, 9, and 10 in the magnetic sensor of the second embodiment shown in FIG. 9
It is the figure shown from the same direction as. In the figure, a third magnetic body 8 is provided so as to connect an intermediate part between the pole teeth of the first magnetic body 9 and an intermediate part between the pole teeth of the second magnetic body 10 adjacent thereto. . For convenience, the first and second magnetic bodies 9 and 10 show only pole teeth.

When the third magnetic body 8 takes the S pole between the pole teeth of the first magnetic body 9 by the magnetic drum 1, the pole of the second magnetic body 10 adjacent between the pole teeth is used. It takes N magnetic poles between teeth. When the third magnetic body 8 has N magnetic poles between the pole teeth of the first magnetic body 9 by the magnetic drum 1, the pole teeth of the second magnetic body 10 adjacent to the pole teeth are provided. Between them, they take the magnetic pole of the S pole. Thus, the third magnetic body 8
Have magnetic poles of N and S poles, and the magnetic fluxes thereof are almost the same, so that the magnets are mutually extinguished, and the third magnetic body 8 becomes magnetically neutral.

For this reason, the influence of the magnetic flux of the magnetic drum 1 facing between the pole teeth of the first and second magnetic bodies 9 and 10 as described above can be reduced, and the first and second magnetic bodies 9 and 10 can be reduced. 9, 1
The magnetic flux converged on the zero main pole increases, and the voltage output obtained from a magnetoelectric conversion element such as a Hall element can be improved. (Embodiment 3) In each of the above embodiments, the magnetic flux of the magnetic drum 1 is converged by a pair of the first magnetic body 9 and the second magnetic body 10,
A change in magnetic flux between the first and second magnetic bodies 9 and 10 is detected as an electric signal by the hall element 7 provided between the first and second magnetic bodies 9 and 10.

In this embodiment, the resolution of the output signal is increased by obtaining a multi-phase output signal having a predetermined electrical angle shift by using a plurality of magnetic flux detection portions having the above-described configuration.

In this embodiment, as shown in FIG. 12, a plurality of magnetic sensors A shown in FIG. 1 are arranged in the axial direction of the magnetic drum 1 and the respective magnetic sensors A are arranged shifted in the circumferential direction. To obtain a polyphase output signal. The use of the multi-phase output signals enables more accurate speed and position control. Here, in order to obtain a multi-phase output signal, precision processing of displacing a plurality of first and second magnetic bodies on each of the sensor cores so as to have a predetermined electrical angle is also required to manufacture a stator core of a stepping motor. It can be easily realized by using a conventional processing method having high mechanical precision used in the above.

It should be noted that the idea shown in each of the embodiments described above is
It is needless to say that the present invention can be applied to a linear motor that moves linearly by providing the first and second magnetic bodies having a magnetic element on a linear motor driving unit and a magnetic structure on a rail.

[0044]

As described above, the present invention reduces the influence of variations in the mounting of the magnetic drum and the magnetic sensor element and the variations in the magnetization of the magnetic pattern of the magnetic drum, provides a large output signal, and provides an amplitude of the output signal. A magnetic sensor with a small difference and high signal accuracy is provided. By mounting the magnetic sensor of the present invention on a motor, it is possible to perform rotation speed control with less rotation unevenness and highly accurate stop position control.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a motor equipped with a magnetic sensor according to a first embodiment of the present invention.

FIG. 2 shows an arrangement relationship between first and second magnetic bodies with respect to a magnetic drum in the magnetic sensor according to the embodiment;
Figure seen from the direction

FIG. 3 is a view of the same arrangement viewed from the direction of arrow C in FIG. 2;

FIG. 4 is a view showing a state of magnetic poles detected by the hall element of the magnetic sensor according to the first embodiment in the state of the magnetic sensor shown in FIGS.

FIG. 5 is a diagram showing an arrangement relationship between first and second magnetic bodies with respect to a magnetic drum in the magnetic sensor according to the first embodiment, as viewed from the direction of arrow B in FIG. 1;

FIG. 6 is a view of the same arrangement viewed from the direction of arrow D in FIG. 5;

FIG. 7 is a view showing a state of magnetic poles detected by the hall element of the magnetic sensor according to the first embodiment in the state of the magnetic sensor shown in FIGS.

FIG. 8 is a diagram showing an output signal waveform of the magnetic sensor according to the first embodiment.

FIG. 9 is a view of the state of the pole teeth of the first and second magnetic bodies and the magnetic flux of the magnetic drum in the magnetic sensor of the present invention, as viewed from the same direction as in FIG.

FIG. 10 is a perspective view of a magnetic sensor including a third magnetic body in the second embodiment.

FIG. 11 is a view of a state of a magnetic flux when a third magnetic body is arranged between the pole teeth of the first and second magnetic bodies when viewed from the same direction as in FIG. 3;

FIG. 12 is a waveform diagram of a multi-phase output signal from the magnetic sensor according to the third embodiment.

FIG. 13 is a diagram showing a configuration of a conventional magnetic sensor.

FIG. 14 is a voltage signal waveform diagram by a conventional magnetic sensor.

FIG. 15 is a diagram showing a configuration of a motor equipped with a conventional magnetic sensor.

FIG. 16 is an output signal waveform diagram of a conventional magnetic sensor incorporating two detection patterns.

FIG. 17 is a block diagram of a control system for controlling the rotation speed and the stop position of the motor.

FIG. 18 is an actual output signal waveform diagram obtained from a conventional magnetic sensor element.

[Explanation of symbols]

 Reference Signs List 1 magnetic drum 3 shaft 4 motor 5 first sensor core 6 second sensor core 7 Hall element 8 third magnetic body 9 first magnetic body 10 second magnetic body

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yoshinori Isomura 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-62-277518 (JP, A) JP-A-52-1759 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01D 5/00 -5/62 G01B 7/00-7/34 G01P 1/00-3/80

Claims (7)

(57) [Claims] 1. A magnetic structure in which N poles and S poles are alternately and continuously magnetized at equal intervals, a plurality of pole teeth facing one magnetic pole of the magnetic structure, and the plurality of pole teeth. First and second magnetic bodies provided with a main magnetic pole for converging magnetic flux generated in parallel to each other, and disposed between the main magnetic poles of the first and second magnetic bodies facing each other. And a magnetoelectric converter that converts a change in transmitted magnetic flux into an electric signal, wherein the first and second magnetic bodies are shifted such that respective pole teeth face two opposite magnetic poles of the magnetic structure. A magnetic sensor, wherein the magnetic structure and the first and second magnetic bodies are relatively movable in an arrangement direction of magnetic poles of the magnetic structure. 2. An opposed magnetic structure which is arranged so as to connect an intermediate portion between pole teeth of a first magnetic body and an intermediate portion between pole teeth of a second magnetic body adjacent thereto. 2. The magnetic sensor according to claim 1, further comprising a third magnetic body that magnetically couples the two magnetic poles. 3. A cylindrical magnetic drum fixed coaxially to a drive shaft of a motor and having N and S poles alternately and continuously magnetized at equal intervals on an outer peripheral surface, and one of the magnetic drums. A plurality of pole teeth facing the magnetic poles of
First and second magnetic bodies provided with main magnetic poles for converging magnetic fluxes generated in the plurality of pole teeth and arranged in parallel with each other, and main magnetic poles opposed to the first and second magnetic bodies And a magnetoelectric converter that converts a change in the magnetic flux to be transmitted into an electric signal, wherein the first and second magnetic bodies are turned into two opposing magnetic poles of the magnetic drum. Magnetic sensors that are staggered to face each other. 4. The magnetic sensor according to claim 3, wherein a plurality of first and second magnetic bodies are arranged at equal intervals on the outer peripheral side of the magnetic drum, and the main magnetic poles are connected in a ring shape. 5. A magnetic drum, which is disposed so as to connect an intermediate portion between the pole teeth of the first magnetic body and an intermediate portion between the pole teeth of the second magnetic body adjacent to the first magnetic body and opposes each other. 5. The magnetic sensor according to claim 3, further comprising a third magnetic body that magnetically couples the two magnetic poles. 6. The magnetic sensor according to claim 1, wherein a ball element is used for the magnetic transducer. 7. A motor on which any one of the magnetic sensors according to claim 1 is mounted.