JPH0923686A - Brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable generation of an energization signal waveform with a magnet of simple shape not using a flange and acquisition of a PG signal without using an exclusive PG magnet, while keeping the number of pulses of FG signal. SOLUTION: The FG poles 31f which are equal to the doubled drive poles 31a are detected by a plurality of Hall elements 18a, 18b, 18c and output frequencies thereof are respectively divided to 1/2 to obtain the energization signal waveform. The phases of the energization signal waveform and the inverse electromotive force waveform are compared. When these phases are inversed with each other, it is assumed that the motor is rotating in the inverse direction and the phase of the waveform after frequency division to 1/2 is set to change 180 degrees.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor equipped with a frequency generator (hereinafter abbreviated as FG) most suitable for VTRs and the like, and a rotational phase detector (hereinafter abbreviated as PG).

[0002]

2. Description of the Related Art A frequency generator (FG: Frequency Generator hereafter abbreviated as FG) as a rotor rotation frequency detecting means and a pulse generator (PG: Pulse Generator hereafter abbreviated as PG) for detecting a rotation phase. The brushless motor provided with is widely used for driving a rotary head drum device of a video tape recorder (hereinafter abbreviated as VTR), and low cost and high performance are strongly demanded.

Conventionally, as a brushless motor for a rotary type VTR rotary head drum device, a three-phase full-wave drive brushless motor with a circumferentially opposed iron core, which has relatively good controllability and high output / low cost, has been widely used. Has been adopted. The rotary head device directly influences the functional performance of the VTR, and the motor used for this requires an FG for controlling the speed of the rotary head. Also, a PG for detecting the rotation phase of the motor is required to switch the rotary head.

The FG and PG used in the conventional motor for the rotary head drum device will be described below with reference to the drawings.

FIG. 23 (a) is a cross-sectional view of a rotary head drum device incorporating a conventional brushless motor therein. Shaft 4 with mirror finish on outer circumference and end face
6 is shrink-fitted and fixed to the rotary drum 40. On the other hand, a plurality of precision-machined wedge-shaped grooves (not shown) are provided at the center of the fixed drum 41. Further, the thrust receiving member 47 is formed so as to close the central through hole of the fixed drum 41.
Are arranged. Here, lubricating oil is drip-drained between the shaft 46, the fixed drum 41, and the thrust receiving member 47, and when the rotating drum 40 rotates in a predetermined direction, dynamic pressure is generated to operate as a fluid bearing and rotate. Rotate the child without contact.

A plurality of video heads (not shown) are arranged on the rotary drum 40. Here, the tape-shaped medium (not shown) is obliquely wound around the fixed drum 41 and the rotating drum 40, and is rotated on the tape-shaped medium by the rotation of the video head (not shown) and the transfer of the tape-shaped medium. Form a video track diagonally. Signals are exchanged between a video head (not shown) and a recording / reproducing circuit (not shown) via a cylindrical rotary transformer 42.

The rotor drum 3 is attached to the rotary drum 40.
The resin-molded magnet 31 is integrally fixed via 0. Further, the stator substrate 44 is fixed to the fixed drum 41 by screws (not shown). This stator board 4
The iron core 21 is fixed on the core 4 via a core holder 45. By applying a predetermined current to the iron core 21,
A coil 20 that generates a rotational biasing force is wound around the magnet 31. In this example, the coil 20 is U-phase,
It is composed of three phases, V phase and W phase, and three pieces for each phase, that is, a total of nine pieces are arranged.

On the inner peripheral cylindrical surface of the magnet 31, drive magnetic poles 31a are provided at equal pitches. In this example, 12 poles are magnetized. Further, the flange portion 31 is provided on the outer peripheral side of the magnet 31.
23g is provided, and an FG magnetic pole 31f is provided on the end face thereof as shown in FIG. 23 (b) at the outer peripheral portion corresponding to the flange portion. In this example, 24, which is a multiple of the driving magnetic pole 31a, is used.
It is magnetized to the pole. The leakage magnetic flux of the driving magnetic pole 31a wraps around the inner circumference of the end surface of the magnet 31, as shown in FIG.

Here, on the stator substrate 44, a comb-shaped F
A G pattern coil (not shown) is arranged to face the FG magnetic pole 31f.

Further, as shown in FIG. 23 (a), one PG magnet 32 magnetized to have a single pole is bonded to the outer periphery of the rotor yoke 30. A PG sensor 33 is arranged on the stator substrate 44 so as to face the PG magnet 32.

Further, the Hall element 18 is arranged so as to interlink with the leakage magnetic flux of the driving magnetic pole 31a which has wrapped around the inner peripheral side of the end surface of the magnet 31. In this example, three are provided.

The operation of the above configuration will be described. The leakage magnetic flux of the driving magnetic pole 31a is linked to the Hall element 18, and three outputs are output from the Hall element according to the rotation of the motor as shown in FIG. This Hall element output Ha, H
b and Hc are waveform-shaped and then processed by a logic circuit (not shown) to generate u, v and w phase coils 20u, 20v,
Energization signal waveforms Pu, Pv, Pw corresponding to 20w are obtained. The energization signal waveforms Pu, Pv, and Pw have a rectangular wave shape of 120 degrees in both positive and negative electrical angles, and the electrical angles are deviated from each other by 120 degrees.

On the other hand, the magnetic flux of the driving magnetic pole 31a of the magnet 31 is linked to the coil 20 via the iron core 21. Here, in the u, v, w phase coils 20u, 20v, 20w,
As shown in FIG. 5, back electromotive forces Bu, Bv, Bw are generated respectively. A current proportional to the waveform of the energization signal is applied to each coil, and the rotor of the motor rotates in a predetermined direction by this.

By such rotation, an FG coil (not shown)
The magnetic flux of the FG magnetic pole 31f interlinking with the magnetic flux changes, and a rotation frequency signal (hereinafter referred to as FG
Signal). In this embodiment, FG
Since the magnetic pole 31f is magnetized to have 24 poles, it is possible to obtain a sinusoidal FG signal having 12 pulses per rotation.

This FG signal is input to a drive control circuit (not shown) of the brushless motor, and rotation control is performed so that the signal period becomes a predetermined value.

Further, the PG sensor 33 interlinks with the leakage magnetic flux of the PG magnet 32 and generates one PG signal pulse during one rotation of the motor. The rotation phase of the motor is controlled by the drive control circuit so that the PG signal pulse maintains a predetermined phase relationship with the video signal and the like.

[0017]

However, the above conventional example has the following problems. In the conventional example, in order to obtain the energization signal waveform and the FG signal, it is necessary to provide magnetic poles having different numbers of poles on the end surface of the magnet 31. This is because it is necessary to detect the signals Ha, Hb, Hc synchronized with the back electromotive force waveforms Bu, Bv, Bw of the coil 20 by the hall element 18 in order to obtain the energization signal waveform. on the other hand,
This is because it is better to increase the number of FG pulses during one rotation in order to improve the rotation controllability of the motor. for that reason,
The magnet 31 had to be provided with the flange portion 31g to increase the radial area of the end surface of the magnet 31.

As a result, the outermost diameter of the magnet 31 is increased,
Since there is no choice but to reduce the thickness of the outer peripheral portion of the fixed drum 41, there is a problem that the processing accuracy of the fixed drum 41 cannot be sufficiently obtained. In order to avoid this, it is conceivable to reduce the outer diameter of the magnet 31, but this will significantly deteriorate the torque characteristics of the motor.

Further, in order to provide the flange portion, the magnet 31
Is complicated, and it is necessary to perform resin molding in order to obtain that shape. As a result, it becomes impossible to use extremely inexpensive magnet materials such as sheet-shaped rubber magnets.
This will lead to higher costs.

Here, in order to obtain higher motor characteristics, it is necessary to make the magnet 31 anisotropic, but when molding the magnet 31, an external magnetic field is applied so that the magnetic field is oriented in the magnetization direction. The need arises.

The magnetic field orientation of the sheet-shaped rubber magnet or the like may be applied in the plane direction at the stage of rolling into a sheet shape, and thereafter, a desired shape can be obtained only by cutting into a strip shape. As a result, it is difficult to form a complicated shape for the rubber magnet, but it is not necessary to prepare a dedicated mold according to the shape of the product, and the manufacturing cost can be kept extremely low.

On the other hand, when the magnet 31 is manufactured by resin molding, it is necessary to construct a magnetic field orientation magnetic field generating coil inside the mold, and it is necessary to use a mold that is more expensive than a normal resin molding mold. Occurs, resulting in an increase in the unit price of parts.

Further, the PG magnet 32 needs to be fixed to the outer periphery of the rotor yoke 30 by adhesion or the like, which also causes a cost increase. Further, since it projects outward from the outer periphery of the rotor yoke 30, it is necessary to provide a relatively large gap between the inner peripheral wall surface of the fixed drum 41 and the outer periphery of the rotor yoke 30, and as a result, the drive magnetic pole 31a portion is not formed. It was necessary to reduce the diameter.

Further, since the PG signal is obtained by the PG sensor 33 and the PG magnet 32, there is a problem that the generation phase of the PG signal is easily influenced by the assembly accuracy.

Therefore, in view of the above problems, it is an object of the present invention to rationalize the number of pulses of the FG signal by using a simple magnet without using a flange or the like.

[0026]

In order to achieve the above object, the present invention detects a FG magnetic pole which is a multiple of the driving magnetic pole by a plurality of Hall elements and obtains a signal obtained by dividing the output by two. After making the energization signal waveform, the obtained energization signal waveform and the phase of the back electromotive force waveform are compared and judged. If this is the opposite phase, it is judged that the motor is rotating in reverse and the frequency is divided by two. It was so constructed that the phase of the subsequent waveform was changed by 180 degrees.

Further, after the energization signal waveform is prepared in the same manner as above, if the signs of the obtained three-phase energization signal waveforms are all the same, it is judged that the motor is rotating in the reverse direction, and the frequency is divided by two. It was configured to change the phase of the waveform by 180 degrees.

Further, one magnetic field non-uniform portion is provided on the position detecting magnetic pole, and the PG sensor is arranged to face the position detecting magnetic pole with a predetermined phase difference with respect to one of the position detecting Hall elements. The output from the Hall element for position detection is added to or subtracted from this PG sensor output.

Further, one magnetic field non-uniform portion was provided on the position detecting magnetic pole, and a plurality of position detecting Hall elements were arranged so as to face the position detecting magnetic pole, and the sum of the Hall element outputs was calculated.

Further, when a strip-shaped magnet made of a flexible material is fitted to the cup-shaped rotor yoke, a chamfer is provided at the joint of the magnet, and the magnet is magnetized so that the magnetic pole center of the driving magnetic pole is located at this joint. did.

Further, when a strip-shaped magnet made of a flexible material is fitted to the cup-shaped rotor yoke, a chamfer is provided at the joint portion of the magnet, and the magnet is magnetized so that the magnetic pole center of the driving magnetic pole is located at this joint portion. Then, a plurality of cutouts having substantially the same shape as the cutouts in this joint portion were provided on the cylindrical end surface of the magnet on the side not facing the Hall element.

Further, one magnetic field non-uniform portion was provided on the driving magnetic pole, and PG coils having winding directions opposite to each other were wound around the auxiliary pole of the super heteropolar iron core.

[0033]

With the above structure, FG magnetic poles which are twice as many as the driving magnetic poles are provided, the signal detected by the Hall element is divided by 2 to generate the energizing signal waveform, and the erection signal waveform is generated in reverse. By detecting the reverse rotation by comparing and judging the phase with the electric power waveform, the FGs having different magnetic pole numbers on the magnet end face.
It is not necessary to provide a magnetic pole and a magnetic pole for position detection. As a result, it is not necessary to provide a flange or the like on the end surface of the magnet, and it is possible to use an extremely low-cost magnet material such as a rubber magnet for the magnet. Further, the outer diameter of the motor can be suppressed to be small.

In addition, since the energization signal waveform is similarly produced and the reverse detection is performed by comparing and judging all the signs of the energization signal waveform, the number F of magnetic poles on the magnet end face is different from each other.
It is not necessary to provide the G magnetic pole and the position detecting magnetic pole. As a result, the same effect as that of the first invention can be obtained.

Further, by providing one magnetic field non-uniform portion on the position detecting magnetic pole and adding or subtracting the output of the position detecting Hall element and the output of the PG sensor arranged with a predetermined phase difference, It is possible to obtain a PG signal waveform having a good SN ratio without using the PG magnet.

Further, by providing one magnetic field non-uniform portion on the magnetic pole for position detection and adding all outputs of the Hall element output for position detection, the SN ratio can be obtained without using a dedicated PG magnet or PG sensor. It is possible to obtain a good PG signal waveform.

Further, since a strip-shaped magnet made of a flexible magnet material is chamfered on the end face of the joint when the magnet is fitted to the rotor yoke, one magnetic field non-uniform portion is formed on the magnetic pole for position detection. The non-uniform magnetic field can be provided without using the PG magnet.

In addition, since a strip-shaped magnet made of a flexible magnet material is chamfered on the end face of the joint when the magnet is fitted to the rotor yoke, one magnetic field non-uniform portion is formed on the position detecting magnetic pole. The non-uniform magnetic field can be provided without using the PG magnet. Further, since a plurality of cutouts having substantially the same shape as the cutout formed by the chamfered portion are provided on the cylindrical end surface on the side opposite to the position detecting magnetic pole, the magnetic field nonuniformity portion of the cutout is opposite to that of the exciting coil. It is possible to reduce the non-uniformity that affects the electromotive force waveform.

In addition, the super heteropolar type iron core 2
Winding search coils in opposite directions around one commutating pole
Since the coil is configured, the influences of the magnetic field from the exciting coil are canceled by each other, and it is possible to obtain a PG signal having an extremely good SN ratio and phase accuracy.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. The description of the points that are the same as those of the conventional configuration will be omitted.

In FIG. 1A, a cylindrical magnet 31 is integrally fixed to the rotary drum 40 via a rotor yoke 30. Further, the stator substrate 44 is fixed to the fixed drum 41 by screws (not shown). The iron core 21 is placed on the stator substrate 44 via the core holder 45.
Has been fixed. A coil 20 is wound around the iron core 21 to generate a rotational urging force between the iron core 21 and the magnet 31 by performing a predetermined energization. In this example, coil 2
0 consists of U-phase, V-phase and W-phase.
Are arranged.

As shown in FIG. 1B, driving magnetic poles 31a are provided on the inner cylindrical surface of the magnet 31 at equal pitches. In this example, 12 poles are magnetized. Further magnet 31
An FG magnetic pole 31f is provided on the end face of the. In this example, 24 poles, which is a multiple of the drive magnetic pole 31a, are magnetized. As shown in FIG. 2A, Hall elements 18a, 18b, 18c are provided on the stator substrate 44 so as to face the FG magnetic pole 31f.
Is arranged.

On the outer peripheral portion of the FG magnetic pole 31f, only one reverse magnetized PG magnetic pole 31b is provided.

The operation of the brushless motor thus configured will be described below. The leakage magnetic flux of the FG magnetic pole 31f is linked to the Hall elements 18a, 18b, 18c, and three Hall element outputs Ha, Hb, Hc are output from the Hall element according to the rotation of the motor as shown in FIG. Here, the Hall element outputs Ha, Hb, and Hc form a signal of 12 cycles per rotation.

Here, the rising edge of the Hall element output Ha is detected to produce the FG output signal FG_OUT. The FG output signal FG_OUT is input to the drive control circuit of the brushless motor, and rotation control is performed so that the signal cycle becomes a predetermined value.

The hall element output Ha has a PG magnetic pole 3
There is a cycle in which the output level is low once per revolution due to the reversal pole of 1b. Other Hall element outputs Hb, Hc
The same is true for Here, the Hall element output Ha is compared with whether the output level of each cycle exceeds a predetermined value SPG,
The waveform is shaped so as to output a HIGH output when it exceeds, and a LOW output when it does not exceed. Further, the PG shaped waveform obtained here is compared with FG_OUT, and FG
If the PG shaping waveform is not HIGH when _OUT is HIGH, a PG output signal PG_OUT that generates a PG pulse at the next rising edge of FG_OUT is generated.
The drive control circuit controls the rotation phase of the motor so that the PG output signal PG_OUT maintains a predetermined phase relationship with the video signal and the like.

On the other hand, the Hall element outputs Ha, Hb, and Hc are, as shown in FIG.
Each of them is sequentially divided by 2 to become Ha divided Ha2, Hb divided Hb2, Hc divided Hc2. This Ha division Ha2
The Hb frequency divider Hb2 and Hc frequency divider Hc2 are processed by the energization signal generator to generate u, v, w phase coils 20u, 20v, 2
Energization signal waveforms Pu, Pv, Pw corresponding to 0w are obtained.
The energization signal waveforms Pu, Pv, and Pw have a rectangular wave shape of 120 degrees in both positive and negative electrical angles, and the electrical angles are deviated from each other by 120 degrees.

On the other hand, the magnetic flux of the driving magnetic pole 31a of the magnet 31 is linked to the coil 20 via the iron core 21. Here, counter electromotive forces Bu, Bv, Bw are generated in the u, v, w phase coils 20u, 20v, 20w, respectively, as shown in FIG. A current proportional to the waveform of the energization signal is applied to each coil, and the rotor of the motor rotates in a predetermined direction by this.

FIG. 5 shows the above-mentioned sequential ½ dividing means.
This will be described with reference to FIG. The Hall element outputs Ha, Hb, and Hc are input to the waveform shapers 1a, 1b, and 1c, respectively, and shaped into a substantially rectangular wave, and shaped waveforms Ha1, Hb1, and Hc1.
Becomes

First, the shaped waveform Ha1 is input to the frequency divider 2a, and becomes a divided-by-2 output Ha20 whose sign changes every wavelength of the shaped waveform Ha1. Therefore, the frequency of the frequency-divided output Ha20 is half the frequency of the shaped waveform Ha1.

The halved output Ha20 is input to the integrator 6. In the integrator 6, the rotation direction signal C1 of the motor is also input at the same time, and the frequency-divided output Ha20 and the rotation direction signal C1 are integrated to obtain a frequency-divided output Ha that is the integration result.
2 is output. Here, the rotation direction signal C1 is defined by the reverse rotation detecting means, which will be described later, and is 1 when the rotation direction motor is rotating in the normal direction and -1 when the rotation direction motor is rotating in the reverse direction.

As a result, when the motor is rotating in the normal direction, the frequency-divided output Ha20 and the frequency-divided output Ha2 have the same phase and the same output.

On the other hand, when the motor is rotating in the reverse direction, the frequency-divided output Ha20 and the frequency-divided output Ha2 have opposite phases and the same output.

The rising edge of the shaped waveform Hb1 is detected by the rising edge detector 3b, and the edge signal Eb is produced. The frequency of this edge signal Eb is the same as the frequency of the Hall element output Hb.

The edge signal Eb is input to the frequency division reference pulse generator 4b together with the frequency division output Ha2 and becomes a frequency division reference pulse Rb which is the result of mutual integration. That is, the divided reference pulse Rb becomes a signal having positive and negative polarities, and its frequency is half that of the edge signal Eb.

The frequency-divided reference pulse Rb thus obtained is input to the frequency divider 2b together with the shaped waveform Hb1. This frequency divider 2b is HI when the frequency division reference pulse Rb becomes positive.
The GH output is configured to produce a LOW output when the divided reference pulse Rb becomes negative.

As a result, the frequency-divided output Hb2, which is the output of the frequency-divider 2b, has the same frequency as the frequency-divided output Ha2, and becomes a signal whose phase is delayed by 20 ° in mechanical angle and 120 ° in electrical angle.

The rising edge of the shaped waveform Hc1 is detected by the rising edge detector 3c to produce an edge signal Ec. The frequency of this edge signal Ec is the same as the frequency of the Hall element output Hc.

This edge signal Ec is input to the frequency division reference pulse generator 4c together with the frequency division output Hb2 and becomes a frequency division reference pulse Rc which is the result of mutual integration. That is, the divided reference pulse Rc becomes a signal having positive and negative polarities, and its frequency is half that of the edge signal Ec.

The frequency-divided reference pulse Rc thus obtained is input to the frequency divider 2c together with the shaped waveform Hc1. This frequency divider 2c is HI when the frequency division reference pulse Rc becomes positive.
The GH output is configured to produce a LOW output when the divided reference pulse Rb becomes negative.

As a result, the frequency-divided output Hc2 which is the output of the frequency-divider 2c has the same frequency as the frequency-divided output Ha2, and becomes a signal whose phase is delayed by 40 degrees in mechanical angle and 240 degrees in electrical angle.

The divided waveforms Ha2 and Hb thus obtained
2, Hc2 is input to the energization signal generator 5, and then u,
The energization signal waveforms Pu, Pv, Pw correspond to the v, w-phase coils 20u, 20v, 20w.

Here, it is assumed that the motor starts rotating in the opposite direction. This is a case where the phase of the divided-by-2 output Ha20 is inverted by 180 degrees with respect to the normal phase,
The signal waveform is as shown in FIG. In such a case, the obtained energization signal waveform Pu and counter electromotive force waveform Bu
And have opposite phase relationships. Therefore, the rotation direction of the motor can be detected by comparing the phase relationship between Pu and Bu.

FIG. 8 is a block diagram for explaining the reverse rotation detecting means. The u-phase back electromotive force waveform Bu is input to a low-pass filter (LPF) 8 to obtain a signal Bu ₁ from which high frequency components have been removed. Further, the u-phase energization signal Pu is input to the latch 9, and when the value changes from 0, the value at that time becomes the held signal Pu ₁ . The signal Bu ₁ and the signal Pu ₁ are input to the sign comparator 7pb. here,
If the product of the two is positive or 0 (when rotating in the forward rotation direction), 1 is generated, and if it is negative (when rotating in the reverse rotation direction), a rotation direction signal C1 having a value of -1 is formed.

By inputting the rotation direction signal C1 to the integrator 6 in FIG. 5, reverse rotation can be prevented.

Therefore, according to this embodiment, the driving magnetic pole 31 is
Since the energization signal waveforms Pu, Pv, and Pw can be produced even if the FG magnetic pole 31f that is a multiple of a is detected by the Hall element, the drive magnetic pole 31a and the FG magnetic pole are provided on the cylindrical end surface of the magnet 31 as in the conventional case. 31f and need not be provided,
As a result, it is not necessary to provide the magnet 31 with a flange portion. As a result, since the magnet 31 does not need to be resin-molded, an extremely inexpensive rubber magnet or the like can be used.

In this embodiment, the PG magnetic pole 31b is used.
Is a reversal magnetic pole, but the present invention is not limited to this, and the magnetic field strength in this portion may be weakened or may be zero.

Further, in this embodiment, a PG magnet and a PG
Although a sensor is not used, the present invention is not limited to this, and the PG unit may have any other configuration.

Further, the FG signal does not necessarily need to use the Hall element output, but may use, for example, a comb-tooth-shaped FG pattern.

Further, in this embodiment, the motor adopts the three-phase full-wave drive system, but this can be applied to the three-phase half-wave drive system.

Further, the rotation direction signal is integrated with the output of the frequency divider 2a by the integrator 6 in the sequential frequency dividing means in the above embodiment, but the present invention is not limited to this. An integrator 6 may be arranged immediately before the energization signal generator 5 for each phase, and the divided waveform of each phase may be multiplied by the rotation direction signal C1.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the motor is a so-called face-to-face type. The magnet 31 has a driving magnetic pole 31a formed on the outer peripheral portion thereof and an FG magnetic pole 31f formed on the inner peripheral portion thereof. Also in this embodiment, the FG magnetic pole 31f has magnetic poles twice the number of poles of the driving magnetic pole 31a.

Even with such a configuration, it is possible to obtain the energization signal waveform exactly as in the first embodiment.

Further, in the first and second embodiments, the case where the number of poles of the driving magnetic pole 31a is 12 has been taken as an example, but this value can be any other value.

Next, a third embodiment of the present invention will be described. In this embodiment, the rotation direction detecting means is different from that of the previous embodiment. Therefore, the description of the overlapping points will be omitted.

When the motor in this embodiment is reversed,
The Hall element outputs Ha, Hb, Hc and the divided waveform Ha
2, Hb2 and Hc2 have a phase relationship as shown in FIG. As shown in the figure, the divided waveforms Ha2, Hb2, Hc2
Has an area where all the codes are the same. Therefore, in the present invention, when all of these signs are the same, it is judged that they are reversed.

FIG. 11 shows a block diagram of the reverse rotation detecting means in this embodiment. The divided waveforms Ha2 and Hb2 are input to the code comparator 7ab. Here, if the product of both is positive (that is, the same sign), it is 1, negative (that is, a different sign), or 0
Then, a signal C0 having a value of −1 is produced.

The signal C0 and the divided waveform Hc2 are input to the code comparator 7abc. Here, the rotation direction signal C1 having a value of 1 if the product of both is negative or 0, and -1 otherwise is produced.

Here, C1 which is the product of the signal C0 and the divided waveform Hc2 becomes negative or 0 (in this case, C1 = 1), because one of the three divided waveforms Ha2, Hb2 and Hc2 is The other two are when the signs are different (that is, in the forward rotation direction).

Further, the product of the signal C0 and the divided waveform Hc2, C1 becomes positive (in this case, C1 = -1) is 3
It shows that there is a phase (reverse state) where all the two divided waveforms Ha2, Hb2, Hc2 have the same sign.

By inputting this rotation direction signal C1 to the integrator 6 in FIG. 5, it becomes possible to prevent reverse rotation.

Therefore, according to this embodiment, the driving magnetic pole 31 is
Since the energization signal waveforms Pu, Pv, and Pw can be produced even if the FG magnetic pole 31f that is a multiple of a is detected by the Hall element, the drive magnetic pole 31a and the FG magnetic pole are provided on the cylindrical end surface of the magnet 31 as in the conventional case. 31f and need not be provided,
As a result, it is not necessary to provide the magnet 31 with a flange portion. As a result, since the magnet 31 does not need to be resin-molded, an extremely inexpensive rubber magnet or the like can be used.

Further, in this embodiment, the motor adopts the three-phase full-wave drive system, but it can be applied to the three-phase half-wave drive system.

Further, the rotation direction signal is integrated with the output of the frequency divider 2a by the integrator 6 in the sequential frequency dividing means in the above embodiment, but the present invention is not limited to this. An integrator 6 may be arranged immediately before the energization signal generator 5 for each phase, and the divided waveform of each phase may be multiplied by the rotation direction signal C1.

Next, a fourth embodiment of the present invention will be described. The description of the points that are the same as those of the conventional configuration will be omitted.

In FIG. 1, on the inner peripheral cylindrical surface of the magnet 31,
As shown in FIG. 1B, the driving magnetic poles 31a are provided at equal pitches. In this example, 12 poles are magnetized. Further, an FG magnetic pole 31f is provided on the end surface of the magnet 31. In this example, 24 poles, which is a multiple of the drive magnetic pole 31a, are magnetized. Further, the PG magnetic pole 31b which is inversely magnetized is provided only at one location on the outer peripheral portion of the FG magnetic pole 31f.

As shown in FIG. 2B, four Hall elements 18a, 18b, 18c and 18d are arranged on the stator substrate 44 so as to face the FG magnetic pole 31f. Of these, three Hall elements 18a, 18b, 18c are shown in FIG.
As shown in FIG. 3, the iron core 21 is arranged in phase with the winding groove portion. On the other hand, the Hall element 18d is
The FG magnetic poles 31f are arranged with their phases shifted by two poles.

The operation of the brushless motor thus constructed will be described below. The leakage magnetic flux of the FG magnetic pole 31f is linked to the Hall elements 18a, 18b, 18c and 18d, and the Hall elements output four Hall element outputs Ha, Hb, Hc, as shown in FIG. Hd
coming out. Here, Hall element outputs Ha, Hb, Hc, Hd
Produces a signal of 12 cycles per revolution. Further, the Hall element outputs Ha, Hb, and Hc are generated with their electrical phases shifted from each other by 120 degrees. On the other hand, the Hall element output Hd is out of phase with the Hall element output Hc by 360 degrees.

Hall element outputs Hc and H thus obtained
d is input to the PG signal producing means (subtractor 11) shown in FIG. 13, and as shown in FIG.
Generate the G output waveform. The Hall element outputs Hc and Hd are input to the subtractor 11, and a subtraction of Hc-Hd is performed.

Since the Hall element outputs Hc and Hd have signal waveforms that are out of phase with each other by 360 degrees,
By subtracting from each other, the signal component of the other part of the FG magnetic pole 31f is canceled and the signal component of only the PG part can be taken out with a high S / N ratio.

Since the construction for producing the energization signal waveform and the reverse rotation detection signal is the same as that of the above-mentioned embodiment, its explanation is omitted.

As described above, according to this embodiment, it is possible to produce a PG signal with a very simple structure, and it is possible to reduce the cost. Further, unlike the conventional case, since it is not necessary to use a PG magnet, it is not necessary to reduce the outer diameter of the motor, and the motor characteristics can be improved.

In this embodiment, the FG magnetic pole 31f has the number of poles which is a multiple of the driving magnetic pole 31a. However, the present invention is not limited to this, and the number of magnetic poles may be the same.

Further, in this embodiment, the Hall element Hd
Has shifted the phase of the FG magnetic pole by two poles with respect to the Hall element Hc, but the present invention is not limited to this.
It may be an integral multiple of the magnetic pole opening angle of 1f. However, in the case of an odd multiple, an adder may be used instead of the subtractor 11.

Next, a fifth embodiment of the present invention will be described. The description of the points that are the same as those of the conventional configuration will be omitted.

In FIG. 1, on the inner peripheral cylindrical surface of the magnet 31,
As shown in FIG. 1B, the driving magnetic poles 31a are provided at equal pitches. In this example, 12 poles are magnetized. Further, as shown in FIG. 1B, an FG magnetic pole 31f is provided on the end surface of the magnet 31. In this example, 2 of the driving magnetic poles 31a
It is magnetized to a multiple of 24 poles. Further, the PG magnetic pole 31b which is inversely magnetized is provided only at one location on the outer peripheral portion of the FG magnetic pole 31f.

Two Hall elements 18a, 18b, 18c are arranged on the stator substrate 44 so as to face the FG magnetic pole 31f, as shown in FIG. 2 (a). As shown in FIG. 14, the three Hall elements 18a, 18b, 18c are arranged in phase with the winding groove portion of the iron core 21.

The operation of the brushless motor thus constructed will be described below. The leakage magnetic flux of the FG magnetic pole 31f is linked to the Hall elements 18a, 18b, and 18c, and the Hall elements 18a, 18b, and 18c generate 3 as shown in FIG.
Two Hall element outputs Ha, Hb, Hc are output. Here, the Hall element outputs Ha, Hb, and Hc form a signal of 12 cycles per rotation. Further, the Hall element outputs Ha, Hb, and Hc are generated with their electrical phases shifted from each other by 120 degrees.

Hall element outputs Ha and H thus obtained
b and Hc are PG signal producing means (adder 1) shown in FIG.
0) to generate a PG output waveform as shown in FIG.

Since the Hall element outputs Ha, Hb, and Hc have signal waveforms that are 120 degrees out of phase with each other, by adding all of them, the signal component of the other portion of the FG magnetic pole 31f is canceled, It is possible to take out the signal component of only the PG part with a high S / N ratio.

Since the construction for producing the energization signal waveform and the reverse rotation detection signal is the same as that of the above-mentioned embodiment, its explanation is omitted.

As described above, according to this embodiment, it is possible to produce a PG signal with a very simple structure, and it is possible to reduce the cost. Further, unlike the conventional case, since it is not necessary to use a PG magnet or a PG sensor, it is not necessary to reduce the outer diameter of the motor, and the motor characteristics can be improved.

In this embodiment, the FG magnetic pole 31f has the number of poles which is a multiple of the driving magnetic pole 31a. However, the number of poles is not limited to this, and the number of magnetic poles may be the same.

Next, a sixth embodiment of the present invention will be described. The description of the points that are the same as those of the conventional configuration will be omitted.

On the inner peripheral cylindrical surface of the magnet 31, drive magnetic poles 31a are provided at equal pitches as shown in FIG. The magnet 31 is made by cutting a flexible magnet material into a strip shape, and the magnet 31 is fitted into the cup-shaped rotor yoke 30. A developed view of the magnet 31 is shown in FIG. As shown in FIG. 17 (a), chamfered portions are formed on both ends thereof. When the magnet 31 is magnetized, its joint 31d is magnetized so as to substantially coincide with the circumferential center of the driving magnetic pole 31a.

Two Hall elements 18a, 18b and 18c are arranged on the stator substrate 44 so as to face the end faces of the magnet 31 as shown in FIG. 2 (a).

The operation of the brushless motor thus configured will be described below. The leakage magnetic flux of the driving magnetic pole 31a is linked to the Hall elements 18a, 18b, 18c, and a signal of 6 cycles is generated from the Hall element according to the rotation of the motor. However, since the magnet 31 has the chamfered portion 31c,
The level of the Hall element output corresponding to this portion decreases. If the result is subjected to signal processing as in the fourth aspect of the invention, a PG signal can be generated.

In this embodiment, the driving magnetic pole 31a is used.
Since the joint 31d is located at the center, the disturbance generated in the back electromotive force waveform of the exciting coil can be small.

Since the chamfered portion 31c is provided on the joint portion 31d, the phase determination when fitted on the rotor yoke 30 becomes easy, and as a result, the phase determination during magnetization can be made extremely accurate. .

Further, as in the conventional case, the joint portion 31d of the magnet 31 is formed.
If the chamfered portion 31c does not exist in the rubber magnet, burrs or the like may occur when the rubber magnet is cut, and this may slide with the hall element 18 or the iron core 21 to deteriorate the rotation accuracy. According to the embodiment, generation of such harmful burr is suppressed.

As described above, according to the present embodiment, it is not necessary to perform the PG magnet and the reversal magnetization as in the conventional example, and the chamfered portion is formed on the end surface of the magnet. The signal can be produced, and the cost can be reduced. Also, as before,
Since it is not necessary to use a PG magnet or a PG sensor, it is not necessary to reduce the outer diameter of the motor, and the motor characteristics can be improved.

Although the FG magnetic pole 31f is not provided in this embodiment, magnetic poles having the number of poles of the driving magnetic pole 31a may be provided on the cylindrical end surface of the magnet 31.

Further, in this embodiment, the chamfering is provided only at two places, but it may be provided at four places as shown in FIG. 17 (b). In this way, the magnet 31 is connected to the rotor yoke 3
Since it is not necessary to specify the insertion direction when fitting into 0, workability can be improved.

Next, a seventh embodiment of the present invention will be described. The description of the points that are the same as those of the conventional configuration will be omitted.

On the inner peripheral cylindrical surface of the magnet 31, drive magnetic poles 31a are provided at equal pitches as shown in FIG. The magnet 31 is made by cutting a flexible magnet material into a strip shape, and the magnet 31 is fitted into the cup-shaped rotor yoke 30. FIG. 18 shows the developed shape. When the magnet 31 is magnetized, the joint 31d is magnetized so as to be located substantially at the center of the driving magnetic pole 31a in the circumferential direction.

Two Hall elements 18a, 18b and 18c are arranged on the stator substrate 44 so as to face the end faces of the magnet 31 as shown in FIG. 2 (a).

As shown in FIG. 18, the magnet 31 has two chamfered portions 31c at both ends thereof, and the chamfered portions 31c face the Hall elements 18a, 18b, 18c. Further, a plurality of notch portions 31e are formed in a portion corresponding to the cylindrical end surface on the side opposite to the chamfered portion. The notch 31e has substantially the same shape as the V-shaped notch formed by the chamfer 31c.

The operation of the thus configured brushless motor will be described below. The leakage magnetic flux of the driving magnetic pole 31a is linked to the Hall elements 18a, 18b, 18c, and a signal of 6 cycles is generated from the Hall element according to the rotation of the motor. However, since the magnet 31 has the chamfered portion 31c,
The level of the Hall element output corresponding to this portion decreases. If the result is subjected to signal processing as in the fourth aspect of the invention, a PG signal can be generated.

Since a plurality of notches 31e having substantially the same shape as the V-shaped notch formed by the chamfered portion 31c are provided, the nonuniformity of the amount of magnetic flux interlinking with the exciting coil 20 is alleviated. Therefore, the variation in the back electromotive force waveform is reduced, so that even if the back electromotive force waveform of the exciting coil 20 is used for FG, sufficient accuracy can be ensured.

In this embodiment, since the junction 31d is located at the center of the driving magnetic pole 31a, the disturbance generated in the back electromotive force waveform of the exciting coil can be small. As a result, torque ripple and the like can be suppressed.

Since the chamfered portion 31c is provided on the joint portion 31d, the phase determination when fitted to the rotor yoke 30 becomes easy, and as a result, the phase determination during magnetization can be made extremely accurate. .

Further, as shown in a perspective view of the shape of the rotor yoke 30 in FIG.
By providing a (in this example, two locations with 120 ° distribution), it is not necessary to use a special jig or tool for phase determination when fitting the magnet 31.

As described above, according to this embodiment, it is not necessary to perform the PG magnet or reversal magnetization as in the conventional example, and the chamfered portion is formed on the end surface of the magnet. The signal can be produced, and the cost can be reduced. Also, as before,
Since it is not necessary to use a PG magnet or a PG sensor, it is not necessary to reduce the outer diameter of the motor, and the motor characteristics can be improved.

Although the FG magnetic pole 31f is not provided in this embodiment, magnetic poles having the number of poles of the driving magnetic pole 31a may be provided on the cylindrical end surface of the magnet 31.

Further, in this embodiment, the notch portion 31e
Although only two locations are provided, the present invention is not limited to this.
Any number may be used as long as it is arranged at equal intervals with c and is aligned with the magnetic pole center of the driving magnetic pole 31a.

Next, an eighth embodiment of the present invention will be described. The description of the points that are the same as those of the conventional configuration will be omitted.

As shown in FIG. 21, the end surface of the magnet 31 is 1
A reversibly magnetized PG magnetic pole 31b is provided at the magnetic pole center of the driving magnetic pole 31a magnetized to have two poles.

Here, the iron core has a so-called super-heteropolar shape, as shown in the development view of FIG. 20, and the nine main poles 21a are composed of three phases (u, v, w phases). The coil 20 is wound, and the auxiliary pole 21 is provided between the main poles 21a.
Nine b are formed.

The PG coils 22a and 22b, which are search coils, are wound on the commutating pole 21b by the same number of turns so that their winding directions are opposite to each other, and are connected in series. Here, the two auxiliary poles 21b are selected so that the driving magnetic poles facing each other have the same phase. In this embodiment, the compensating poles having a phase shifted by 120 degrees are selected.

The operation of the brushless motor thus configured will be described below. The leakage magnetic flux of the PG magnetic pole 31b is linked to the commutating pole 21b, and a generated voltage is generated in the PG coils 22a and 22b. Here, since the winding directions of the PG coils 22a and 22b are opposite to each other, the PG output terminal 22c outputs the PG in a rotation phase in which the driving magnetic poles 31a facing each other do not face the PG magnetic pole 31b.
The outputs cancel each other to zero.

On the other hand, when one of the PG coils 22a and 22b is opposed to the other coil portion, as shown in FIG. 22, there is a difference between the two outputs, so that PG outputs deviated from each other by 720 electrical degrees are obtained. It will be possible.

As described above, according to this embodiment, the PG
Since the coil is wound to obtain the PG output, it is not necessary to use a PG sensor as in the conventional case, and it is possible to reduce the cost. At the same time, the generation phase of the PG output is almost unique to the processing accuracy of the iron core. Phase error of the PG signal can be made extremely small. Further, since they have mutually canceling effects, it is possible to obtain a PG signal having a very high S / N ratio, which is hardly affected by the leakage magnetic flux from the main pole.

Furthermore, since the PG coils 22a and 22b can be formed simultaneously with the winding of the exciting coil 20,
It hardly causes cost increase.

Since it is not necessary to use a PG magnet or PG sensor as in the conventional case, it is not necessary to reduce the outer diameter of the motor, and the motor characteristics can be improved.

Although the FG magnetic pole 31f is not provided in this embodiment, magnetic poles having the number of poles of the driving magnetic pole 31a may be provided on the cylindrical end surface of the magnet 31.

Further, in this embodiment, the PG magnetic pole is the reversal magnetic pole, but the chamfered portion may be formed as in the above embodiment.

In the above embodiments, the three-phase full-wave drive system is described as an example, but the invention is not limited to this. A Hall element was used as the magnetoelectric conversion element,
It is obvious that an MR element or the like may be used without being limited to this.

[0138]

As described above, in the brushless motor of the present invention, the energization signal can be produced even if the number of magnetic poles that can be effectively used as the FG is twice that of the driving magnetic poles.
Since it is not necessary to provide a flange on the magnet in order to provide the G magnetic pole, there is no need to increase the outer diameter of the brushless motor.

Further, in order to produce a PG signal, by adding only one Hall element, the PG with an extremely high SN ratio can be obtained.
It is possible to obtain a signal, and particularly when applied to a rotary head device or the like, it is possible to simplify the brushless motor configuration, which is effective in cost reduction.

Further, since it is possible to create a PG signal having a high SN ratio only by using the Hall element which has been conventionally used for position detection, it is very promising for cost reduction.

Further, it is possible to obtain the magnetic pole for PG simply by chamfering both ends of the rubber magnet. Therefore, it is not necessary to provide a magnetizing device for PG magnetization, which is promising for cost reduction. Further, the mounting process of the rubber magnet, which has conventionally been difficult to determine the phase of the joint portion with respect to the rotor yoke, can be easily performed by providing the chamfered portion. Further, when the rubber magnet is punched with a die, an end surface burr or the like is likely to occur, which can be mitigated.

Further, the disturbance of the back electromotive force waveform caused by the chamfering is canceled by the V-shaped notch provided on the second end face side as shown in the present invention, so that the control characteristic is improved, As a result, even if the back electromotive force waveform is used as the FG signal, noise is small and high rotation accuracy can be obtained.

In addition, P is used for the super-heteropolar type
Since the G coil is wound, the phases are electrically shifted by 720 degrees from each other, and the coils are wound in the opposite directions, the noise effect is almost complete even in the vicinity of the winding coil for excitation. Will be canceled. In addition, the processing can be completed at the same time as the excitation winding, and there is an advantage that the component cost can be almost ignored. Further, since the phase and waveform shape of the signal are almost uniquely determined by the accuracy of the iron core, it is unlikely to be affected by factors such as assembly error.

[Brief description of drawings]

FIG. 1A is a cross-sectional view of a rotary head device with a built-in brushless motor according to an embodiment of the present invention. FIG. 1B is a perspective view of a rotor according to an embodiment of the present invention.

FIG. 2A is a perspective view of a stator according to an embodiment of the present invention. FIG. 2B is a perspective view of a stator according to an embodiment of the present invention.

FIG. 3 is a time chart of FG / PG in one embodiment of the present invention.

FIG. 4 is a time chart of an energization signal waveform according to an embodiment of the present invention.

FIG. 5 is a block diagram of a sequential divide-by-two frequency dividing means in an embodiment of the present invention.

FIG. 6 is a waveform diagram of a Hall element output and a back electromotive force in one embodiment of the present invention.

FIG. 7 is a signal waveform diagram at the time of reverse rotation of the motor according to the embodiment of the present invention.

FIG. 8 is a block diagram of a reverse rotation detecting means in an embodiment of the present invention.

9A is a cross-sectional view of a rotary head device with a built-in brushless motor according to an embodiment of the present invention. FIG. 9B is a plan view of a magnet according to an embodiment of the present invention.

FIG. 10 is a signal waveform diagram at the time of motor reverse rotation in one embodiment of the present invention.

FIG. 11 is a block diagram of a reverse rotation detecting means in an embodiment of the present invention.

FIG. 12 is a timing chart of Hall element output and the like in one embodiment of the present invention.

FIG. 13 is a block diagram of a PG signal producing means in one embodiment of the present invention.

FIG. 14 is a timing chart of Hall element output and the like in one embodiment of the present invention.

FIG. 15 is a block diagram of a PG signal producing means in one embodiment of the present invention.

FIG. 16 is a perspective view of a rotor yoke portion according to an embodiment of the present invention.

FIG. 17 (a) is a development view of a magnet in one embodiment of the present invention (b) Same as above

[Figure 18] Same development view

FIG. 19 is a perspective view of a rotor yoke according to an embodiment of the present invention.

FIG. 20 is a development view of an iron core and a PG coil according to an embodiment of the present invention.

FIG. 21 is a perspective view of a magnet according to an embodiment of the present invention.

FIG. 22 is a PG signal waveform diagram in one embodiment of the present invention.

23A is a cross-sectional view of a rotary head device with a built-in brushless motor in a conventional example. FIG. 23B is a plan view of a magnet in a conventional example.

FIG. 24 is a signal waveform diagram of a motor in a conventional example.

FIG. 25 is a waveform diagram of a motor energization signal and a back electromotive force waveform in a conventional example.

[Explanation of Codes] 1a, 1b, 1c Waveform shaper 2a, 2b, 2c 2 frequency divider 3b, 3c rising edge detector 4b, 4c frequency division reference pulse generator 5 energization signal generator 6 integrator 7ab, 7pb, 7abc Sign comparator 8 LPF 9 Latch 10 Adder 11 Subtractor 18a, 18b, 18c, 18d Hall element 20 Coil 20u, 20v, 20w u, v, w Phase coil 21 Iron core 21a Main pole 21b Complement pole 22a, 22b PG Coil 22c PG output end 30 Rotor yoke 30a Projection portion 31 Magnet 31a Driving magnetic pole 31b PG magnetic pole 31c Chamfering portion 31d Joining portion 31e Notch portion 31f FG magnetic pole 31g Flange portion 32 PG magnet 33 PG sensor 40 Rotating drum 41 Fixed drum 42 Rotary transformer 44 Stator board 45 Core holder 46 Axis 47 thrust receiving member

Claims (7)

[Claims] 1. A rotary body rotatably supported by a bearing, an annular rotary magnet integrally disposed on the rotary body, and 2n poles (n) at equal pitches on the annular rotary magnet. = 2,
3, 4 ...), drive magnetic poles magnetized, position detecting magnetic poles magnetized to 4n poles at equal pitches on the annular rotary magnet, and X (X ≧ 3) energized phases And the armature, which is arranged to face the magnetic pole surface of the driving magnetic pole and generates a rotational biasing force by switching the energization, and the armature, which is arranged to face the position detecting magnetic pole with a phase shift of 720 / X / n degrees from each other. The X magnetoelectric converters, the sequential halving means for sequentially halving the outputs of the X magnetoelectric transducers, and the energizing signal waveform for driving the motor based on the signals obtained by the halving means. Energizing signal waveform producing means for producing the above, and a reverse rotation detecting means for detecting the back electromotive force of the armature and the phase of the energizing signal waveform, and determining that the rotating body is reversing when the phases are substantially opposite. When the reverse rotation is detected by the reverse rotation detecting means, A brushless motor characterized by changing the phase of the output waveform of the sequential frequency dividing means by 180 degrees. 2. A rotating body rotatably supported by a bearing, an annular rotating magnet integrally disposed on the rotating body, and 2n poles (n) at an equal pitch on the annular rotating magnet. = 2,
3, 4, ...) Driving magnetic poles, position detecting magnetic poles magnetized to 4n poles at equal pitches on the annular rotary magnet, and X (X ≧ 3) energized phases And an armature that is arranged to face the magnetic pole surface of the drive magnetic pole and that generates a rotational biasing force by switching energization, and that faces the position detection magnetic pole with a phase shift of 720 / X / n degrees from each other. The arranged X magnetic-electric converters, a sequential frequency-dividing unit that sequentially divides the output of the X magnetic-electric converters by 2, and a motor based on the X frequency-dividing signals obtained by the sequential frequency-dividing unit. An energization signal waveform producing means for producing an energization signal waveform for driving, and a reverse rotation detecting means for determining that the rotating body is rotating in the reverse direction when the polarities of the X number of divided-by-2 signals are all the same. When the reverse rotation is detected by the reverse rotation detecting means, A brushless motor characterized by changing the phase of an output waveform by 180 degrees. 3. A rotating body rotatably supported by a bearing, an annular rotating magnet integrally disposed on the rotating body, and 2n poles (n) at equal pitches on the annular rotating magnet. = 2,
3, 4) magnetized for driving, a magnetic pole for position detection magnetized for 2n · Z poles (Z = 1 or 2) at equal pitch, and only one position on this magnetic pole for position detection. An armature, which is provided with a non-uniform magnetic field strength portion and X (X = 3, 4, ...) Energized phases, is arranged to face the magnetic pole surface of the drive magnetic pole, and generates a rotational biasing force by switching the energization. And X first magnetic-electric converters which are arranged to face the position-detecting magnetic poles with a phase difference of 720 / X / n degrees from each other, and an energization signal for driving a motor from the output of the first magnetic-electric converters. 180 / n · L / Z degree (L = ± 1, ± 2, ± 3) for any one of the X first magnetoelectric converters for producing a waveform …)
The second magnetoelectric converter, which is arranged so as to face the position-detecting magnetic pole with a phase difference thereof shifted by 180 degrees, is out of phase with the second magnetoelectric converter by 180 / nL / Z degrees. When the output of the first magnetoelectric converter and the output of the second magnetoelectric converter are both added when L is an odd number and subtracted when L is an even number, the rotating body makes one revolution. And a pulse generator that generates a set of pulses while the brushless motor is running. 4. A rotary body rotatably supported by a bearing, an annular rotary magnet integrally disposed on the rotary body, and 2n poles (n) at an equal pitch on the annular rotary magnet. = 2,
3, 4) magnetized for driving, a magnetic pole for position detection magnetized for 2n · Z poles (Z = 1 or 2) at equal pitch, and only one position on this magnetic pole for position detection. An electric machine which is provided with a non-uniform magnetic field strength portion and X (X = 2, 3, 4, ...) Energized phases, which are arranged so as to face the magnetic pole surface of the drive magnetic pole and generate a rotational biasing force by switching the energization. A rotor, X magnetoelectric converters arranged to face the position-detecting magnetic poles with a phase shift of 720 / X / n degrees from each other, and an energization signal waveform for driving a motor is produced from the output of the magnetoelectric converters. And a pulse generator that generates one set of pulses during one rotation of the rotating body by summing the outputs of the X magnetoelectric converters. And brushless motor. 5. A rotary body rotatably supported by a bearing, a rotor yoke having a cup shape and integrally disposed on the rotary body, and a flexible material formed in a strip shape, A magnet having a cylindrical shape fitted into the cup-shaped portion of the rotor yoke, a multi-pole magnetized portion provided on an inner peripheral surface or an end surface portion of the cylinder of the magnet, and a plurality of energized phases. The armature, which is arranged so as to face the surface and generates a rotational biasing force by switching the energization, the magnetoelectric converter, which is arranged so as to face the cylindrical end surface of the magnet, are joined together when the strip-shaped magnet is formed into a cylindrical shape. Of the four corners of the portion, at least two corners on the side facing the magnetoelectric converter are provided with chamfers, and the chamfers are joined when the magnet is formed into a cylindrical shape. To the part Brushless motor, wherein a substantially center of the magnetic poles of the multipole-magnetized portion is disposed so as to be located. 6. A rotating body rotatably supported by a bearing, a rotor yoke having a cup shape and integrally arranged on the rotating body, and a flexible material formed in a strip shape, A magnet having a cylindrical shape fitted into the cup-shaped portion of the rotor yoke, a multi-pole magnetized portion provided on an inner peripheral surface or an end surface portion of the cylinder of the magnet, and a plurality of energized phases. An armature that is arranged opposite to the surface and that generates a rotational biasing force by switching the energization, a magnetoelectric converter that is arranged opposite to the first cylindrical end surface side of the magnet, and when the strip-shaped magnet is formed into a cylindrical shape. A chamfered portion provided at least at two corners of the four corners of the joining portion on the side facing the magnetoelectric converter, and a first cylindrical end surface on which the magnetoelectric converter is arranged to face each other. The second pair of circles A plurality of V-shaped notches arranged on the end surface of the cylinder and having substantially the same shape as the V-shaped notches formed by the chamfered portion are provided, and the magnet in the shape of a cylinder is formed into a cylinder. A brushless motor, characterized in that the magnetic poles of the multi-pole magnetized portion are arranged such that the centers thereof are substantially located at the portions to be joined together when shaped into a shape. 7. A rotating body rotatably supported by a bearing, a rotor yoke having a cup shape and integrally disposed on the rotating body, and a cylindrical shape attached to the cup-shaped portion of the rotor yoke. , A driving magnetic pole magnetized to 2n poles (n = 2, 3, 4 ...) On the inner peripheral surface of the cylinder of this magnet, and magnetic field strength non-uniformity provided at only one location on this driving magnetic pole. Part, an iron core having P main poles (P = 2, 3, 4, ...) Arranged to face the magnetic pole surface of the drive magnetic pole and having excitation windings, and the same number of auxiliary poles. And, the two compensating poles, which are located in a phase apart from each other by 360 / n · K degrees (K = ± 1, ± 2, ± 3 ...), are connected in series and the winding directions are opposite to each other. A brushless motor comprising a pair of search coils wound so that