JPS61240879A - Motor drive device - Google Patents

Abstract

PURPOSE:To enhance the productivity and to reduce the cost by leading the phase information signal and the speed information signal of a rotor on the basis of the prescribed rotation detecting pattern of an element to be detected provided on the rotor, thereby simplifying the construction. CONSTITUTION:The two prescribed types of physical amounts are alternately provided to form a marker 21 on the circumference of the rotor provided in a rotor of a motor, and the physical amount of the marker 21 is detected by a sensor section 22 having one sensor. the output of the section 22 is input to a detection signal generator 23, and the rotation detection signal and the phase detection signal of the repeating frequency proportional to the rotating speed of the rotor is output in the phase relative to the physical amount position of the marker 21. The motor drive circuit 24 outputs a motor drive pulse on the basis of the rotation detection signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a motor drive device, and particularly to a motor drive device for driving a DC brushless motor such as a drum motor of a magnetic recording/reproducing device (VTR).

(Prior Art) Conventionally, a DC brushless motor (Hall motor) using a Hall element has been used as a drum motor for a magnetic recording/reproducing apparatus (VTR). This detects the relative position between the magnetic poles of the rotor and the armature winding (coil) using a Hall element, turns the switching element on and off according to the relative position, and turns the switching element on and off according to the relative position. The rotor is rotated in a fixed direction by sequentially switching the current flowing through the coils (integer number). In this case, in order to use the magnetic flux of the rotor's magnetic poles most effectively, one Hall element is used for each phase, and the rotor's magnetic poles (for example, two values of N and S) corresponding to the coil positions are set. , the current flowing through the coil (+, O
It is necessary to correspond to the three values of , -). Therefore, an m-phase Hall motor requires m Hall elements.

On the other hand, in a general helical scan type VTR, the rotational speed and rotational position of a rotating drum (cylinder) are detected, the rotation of the rotating drum is controlled according to these detection signals, and two video cameras attached to the rotating drum are controlled. The head is controlled to accurately scan (trace) a desired recording (or reproduction) track on the magnetic tape.

That is, in the above-mentioned conventional VTR, a detection head (pickup head: PG head) detects two magnets mounted on a rotating drum at an interval of 180 degrees from each other, and detects two video signals. The rotational phase of the rotating drum corresponding to the head is detected.

In addition, a plurality of magnetic poles are provided at equal intervals on the rotating drum, and the plurality of magnetic poles are detected by a frequency generator III (FG) coil, and the rotation speed of the rotating drum is determined in the form of a detection signal (frequency of the FG multiplied signal). Detected.

Here, an example of a conventional motor drive device will be described. FIG. 9 shows a block system diagram of a drum rotation control device for a conventional helical scan type VTR. 1 shown in the lower right of Figure 9. I [ and ■ are three sets of coils (armature windings) of the driven motor, and their ends are all grounded.

In FIG. 9, the PG head 1 detects two magnetic poles attached to a rotating drum, and the output from the PG head 1 produces rises and falls as shown in waveform a in FIG.
A pulse (P
A G-times signal is obtained as phase information. This PG head 1
The outputs of are supplied to mono multi 2 and mono multi 3, respectively. Mono multi 2 is triggered by the rising edge of waveform a, and mono multi 3 is triggered by the falling edge of waveform a, to obtain waveforms a and c, respectively. And these two mono multi 2.3
Adjust the switching position of the video head (not shown) attached to the rotating drum.

Furthermore, the waveform C is supplied to a flip-flop 70, which is set at the falling edge of the waveform C.
It is reset at the falling edge of waveform C.

Therefore, if the rotating drum (cylinder) is, for example, 30 rps
When rotating at , a drum pulse (DP) having a waveform d corresponding to the switching position of the video head with a repetition frequency of 30 Hz and a duty ratio of 50% is obtained.

This signal of waveform d (drum pulse) is used as a switching pulse and is also supplied to the trapezoidal wave generator 5.

This trapezoidal wave generator 5 generates a trapezoidal wave synchronized with the signal of waveform d and supplies it to the sampling hold circuit 6.

On the other hand, the composite video signal 7 is supplied to a vertical synchronization signal separation circuit (V synchronization separation circuit) 8. Then, the vertical synchronization signal separation circuit 8 generates 601. Only the vertical synchronizing signal is extracted and supplied to the sufficient frequency circuit 9. Therefore, a pulse synchronized with the 30H2 video signal is output from the sufficient frequency circuit 9, and this pulse is supplied to one terminal 10a (RFC) of the switch circuit 10.

On the other hand, the pulse generated from the reference frequency oscillator 11 is passed through the frequency dividing circuit 12 to obtain a 30- reference pulse, and this reference pulse is sent to the other terminal 1 of the switch circuit 10.
0b (PB).

The switch circuit 10 is switched to the terminal 10a side during recording and to the terminal 10b side during playback, thereby selecting the pulses from the sufficient frequency circuit 9 and the frequency dividing circuit 12 and supplying them to the monomulti 13. I try to do that.

The monomulti 13 generates a sampling pulse that is delayed by a certain period of time with respect to the vertical synchronization signal of the video signal during recording.

The sample and hold circuit 6 samples and holds the slope part of the trapezoidal wave using this sampling pulse to obtain a phase error voltage. This phase error voltage is supplied to a loop filter 14 whose purpose is to improve the transient characteristics of the servo loop, and its output (phase error voltage) is supplied to a mixing amplifier 15.

On the other hand, the FG coil 160 detects a plurality of magnetic poles provided at equal intervals on the rotating drum, and from this FG coil 160, a plurality of pulses (FG multiplied signals) existing at equal intervals are obtained as speed information. Pulse is FG pulse amplifier 1
Amplified and waveform shaped at 70, F/V (frequency/voltage)
Converter 180 is provided. This F/V converter 180 converts the frequency of the input signal.

It is a circuit that converts the voltage into a voltage according to the number of rotations, and therefore, a speed error voltage corresponding to the number of rotations of the rotating drum is outputted and supplied to the mixing amplifier 15.

The phase error voltage and speed error voltage are mixed and amplified by a mixing amplifier 15 to obtain an error voltage. This error voltage is
is supplied to the motor drive circuit 16, and this motor drive circuit 1
6 supplies a drive current according to the error voltage to the coil of the motor 17 to rotate and control it.

Next, the motor drive circuit 16 will be explained. The block system diagram in the figure shows a three-phase one-way drive voltage control system. This typically corresponds to each coil 1. of the motor 11. In order to determine the switching position of the current flowing through I1 and III, three Hall elements 18a, 18b,
18C is used. Hall element 18a.

The respective outputs of 18b and 18c are connected to a differential amplifier 19.
a, 19b, and 19c, and their outputs are further supplied to the logic circuit 20.

This logic circuit 20 includes the coils 1. of the motor 17. ■.

(2) Turn on the switching transistors 21a, 21b, and 210 in the subsequent stage so that the current flowing through the circuit switches at the correct position.
This is a circuit for converting into a signal for turning off. By the output of this logic circuit 20, 1-transistor 21a, 2
The output voltage of the mixing amplifier 15 is applied to the coil connected to the turned-on transistor of 1b and 21c, causing current to flow through the coil and driving the motor.

As described above, the drum rotation control device with the above configuration has a mechanism for detecting the rotational phase (that is, two magnets and a pickup head) and a mechanism for detecting the rotational speed (multiple magnetic poles and a frequency generator). ) exist separately, and these two detection mechanisms control the motor armature coil terminal voltage. Furthermore, switching of motor drive current is performed by three Hall elements for a three-phase Hall motor.

(Problems to be Solved by the Invention) As mentioned above, in the conventional motor drive device, m
When controlling a rotating drum (cylinder) using a phase Hall motor, m Hall elements are used to switch the drive current necessary to drive the Hall motor. That is, three mechanisms were required: two magnets and a pickup head) and a mechanism for detecting the rotational speed of the two-rotation drum (a plurality of magnetic poles and a frequency generator). Therefore, the installation and wiring of these mechanisms become complicated, making it difficult to improve productivity and reduce costs.

Therefore, the present invention uses a detection signal detected by a negative sensor to detect a predetermined rotation detection pattern of one detected part provided on a rotating body, and drives a motor for rotating this rotating body. It is an object of the present invention to provide a motor drive device that solves the above problems by making it possible to extract phase information signals and speed information signals of a rotating body.

(Means for Solving the Problems) In order to achieve the above object, the present invention has m phases (where m is 2 or more) as shown in the block diagram of the configuration of the device of the present invention in FIG. Two types of physical quantities are provided alternately on the circumference of a rotating body provided on the rotor of a motor to be driven, which has a coil of (integer). The changing points are sequentially a1,
a2+...

an (however, n is an integer of 3 or more), and this change point a
Let the physical quantities from 1 to an exist at equal intervals, and let the change point where the other physical quantity changes to one physical quantity between the change points an and 81 be a, /, and the change point a
The change point where the other physical quantity changes to one physical quantity existing between 1 and a2 is a2', and the change point where the other physical quantity changes to one physical quantity existing at the gate between the change points a2 and a3 is defined as a2'. Let a, /..., change point a n-
Let the change point between 1 and an at which the other physical quantity changes to one physical quantity be a nI , and these change points a
1′.

a 2/ , a 3J , ... a of a nl
1′.

a 2/ , a 3J ,..., a ′ (however,
r is an integer of 1≦r<n), the maximum value of the detected waveform of one of the two physical quantities adjacent to each of the physical quantities is smaller than the maximum value of the detected waveform of the other physical quantity, and , change point a , I , a 2 (, a , l.

, , , al' , a2' , a3' of a nI
, r.

a, one detected portion in which the minimum value of the detected waveform of the other physical quantity of the two types of physical quantities adjacent to each of I is larger than the minimum value of the detected waveform of the other physical quantity; (marker section) 21, a sensor section 22 having one sensor for detecting the physical quantity of the detected section 21, and a drive current that is applied to the m-phase coil of the motor to be driven based on the detection signal of this sensor section 22. has a phase related to the physical quantity position of the detected part 21 to be switched, and a rotation detection signal with a repetition frequency proportional to the rotational speed of the rotating body and a phase related to the physical quantity position of the detected part,
and a detection signal generation circuit 23 that outputs a pulse phase detection signal corresponding to the rotational phase of the rotating body, and a rotating magnetic field to which the rotation detection signal of the detection signal generation circuit 23 is supplied and for rotating the rotor. To provide a motor drive device comprising a motor drive circuit 24 which generates m-phase drive pulses for the purpose of producing the m-phase coils and outputs them as separate drive currents to the m-phase coils. It is.

(Function) In the motor drive device having the above configuration, a detection signal obtained from a sensor section having a predetermined physical quantity (rotation detection pattern) of a detected part provided on a rotating body and one sensor for detecting the physical quantity is provided. A rotation detection signal is generated, and the rotation detection signal can be used to output a drive current to flow through the coils of each phase of the motor, and furthermore, a phase information signal and a speed information signal of the rotating body can be extracted.

(Example) An example of a motor drive device according to the present invention will be described below with reference to the drawings.

FIG. 2 shows a block system diagram of an embodiment of the device of the present invention. In the figure, the same components as in FIG. 1 are given the same reference numerals. Also, the same parts as in FIG. 9 mentioned above are given the same reference numerals.

The marker section 21 has a magnetization pattern (magnetic pole) applied under the conditions described below, and is, for example, attached to a rotating body integrated with the rotor of a motor that drives a rotating drum (cylinder) as described later. It is configured by applying Wlm.

The sensor section 22 is provided at a position always close to the marker section 21, and includes, for example, one Hall element (sensor) 25 that detects the magnetic flux of the magnetic poles forming the marker section 21. The output detected by this sensor 25 is sent to the differential amplifier 2.
6. (Note that when the sensor 25 is configured with a Hall element, it is normally received by a differential amplifier.) This differential amplifier 26 is a comparator 27A.

278, 27G. Thereafter, through the digital signal processing circuit 28, a pulse (PG multiplied signal) is outputted as phase information at a rate of once per rotation of the rotating drum, and a plurality of pulses (pulses) which are present at equal intervals at a rate of The FG multiplied signal is output as speed information.

The PG multiplied signal, which is phase information, has the waveform a' in Fig. 10.
A pulse like the one shown is obtained. This pulse obtains the waveform bt, c/ shown in FIG. 10 by passing through a monomulti 2 which is triggered at its rising edge and a monomulti 3 which is triggered at its fall. And this waveform b
l and c l are supplied to a flip-flop 4, which is set at the falling edge of waveform b' and reset at the falling edge of waveform C'. Thus, when the rotating drum rotates at, for example, 30 rpS, the repetition rate is 30H.

Drum pulse (DP) as waveform d' corresponding to the switching position of the video head with a duty ratio of 50%
get. Thereafter, the phase error voltage is supplied to the mixing amplifier 15 in the same manner as in the conventional device shown in FIG.

Further, the FG output from the digital signal processing circuit 28
Double signal, FG pulse amplifier 170 and F/V (frequency/
voltage) is supplied to the mixing amplifier 15 via a converter 180. This FG multiplied signal is also supplied to the motor drive circuit 24. That is, in the present invention, the FG multiplication signal is used for the timing of switching the coil current of the motor.

The motor drive circuit 24 includes a pulse generation circuit 29. Switch circuit means 30. Waveform conversion circuit 31 and driver circuit 32
It consists of Further, coils 1 to 2 of the motor 17 are connected to the output end of the driver circuit 32.

In the motor drive circuit 24 having the above configuration, the FG double signal obtained from the output terminal of the digital signal processing circuit 28 constituting the FG double signal and PG signal generation circuit 23, the retriggerable monomulti 33, and the terminal 34a of the changeover switch 34 Supplied.

At startup or at low speed, the changeover switch 34 is switched to the terminal 34b side, and the output from the pulse generation circuit 29 is supplied to the ring counter 36 and the waveform conversion logic circuit 37, respectively. Therefore, the output terminals Q1, Q2 . Pulses are outputted to Q3 in the order of output signals Q1→Q2→Q3. This pulse is then passed through the waveform conversion logic circuit 37 to the transistors T1. T2. T
3 and furthermore, the transistors T ++ , T
Turn on I2 and T I3 in sequence.

As a result, coil 1. It, II[, 1, I1,
The drive current switches in this order, and a rotating magnetic field in the forward rotation direction is generated. Therefore, the main magnetic pole of the motor rotor rotates in the forward rotation direction in synchronization with the rotating magnetic field generated.

On the other hand, when the motor reaches a certain speed or higher (steady rotational speed), the changeover switch 34 is switched to the terminal 34a side by the output of the retriggerable monomulti 33, and the FG double signal is supplied to the ring counter 36. As a result, a rotating magnetic field is generated in the forward rotation direction, and the driving current of the motor can be switched at the correct current switching point, so that the motor rotor rotates continuously.

Further, in the embodiment of the present invention, as shown in FIG. 3, the rotation of the rotating drum is controlled by a direct drive motor in which the rotating drum (cylinder) and the driven motor are directly connected. The structure of the driven motor is such that it satisfies the conditions described below on a rotating body 40 that is integrally attached to a rotor 39 provided with a main magnetic pole (main magnet) 38. There are markers 41 magnetized on the circumference as shown in FIG. Further, the stator 42 is provided with armature coils (hereinafter referred to as coils) 1 to 3,
Furthermore, a sensor 25 is attached at a position facing the marker 41. Further, a rotating drum 44 is connected by a motor shaft 43, and two video heads (magnetic heads) 45a and 45b are attached to this rotating drum 44 at an interval of 180 degrees.

FIG. 4 is a diagram showing the arrangement relationship when main parts of the driven motor shown in FIG. 3 are viewed from above, showing the magnetized state of the main magnetic pole 38 of the rotor 39 and the arrangement of coils 1 to 2.

Position 1 of the sensor 25 represents the magnetized state of the marker 41 of the rotating body 40. Furthermore, the positions of the two video heads 45a and 45b are also noted. In addition, in the figure, the normal rotation direction of the motor is counterclockwise (indicated by arrow R in the figure).

In addition, in order to make it easier to understand the above-mentioned respective positional relationships, FIGS. 5(a) to (e) show coils 1 to ■ in FIG. 4 developed, and the rotor 39 in FIG. An expanded view of the main magnet 38 and marker 41 is also shown. In FIG. 5, the same parts as in FIG. 4 are given the same reference numerals.

As shown in FIG. 5 (a>), there are three sets of coils, which are represented by ■1 to Ia, I[+ to IIt, n[+ to ■4, and I4.[4, I[[ 4 are respectively grounded. Assume that the rotor 39 of FIG. 4 is initially in the position shown in FIG. 5(b) for the three sets of coils 1 to 4.

That is, the positional relationship between FIG. 4 and FIG. 5(b) corresponds accurately, and the positions of A and B in each figure also correspond.

Now, let us assume that the position of the sensor 25 is 8. The main magnetic pole 38 is the fifth
As shown in Figures (b) to (e), the N and S poles are arranged alternately in 4
Each pole is magnetized at equal angular intervals, totaling 8 poles.

Further, the marker 41 magnetized on the rotating body 40 is also the fifth marker.
As shown in Figures (b) to (e), the main magnetic pole 38 is magnetized.
and rotates together with the video heads 45a and 45b. Then, when the rotor 39 rotates in the forward direction, as shown in FIG.
)-) FIG. 5(d)-) FIG. 5(e).

Here, the following conditions are required for the magnetization pattern of the marker 41 magnetized on the circumference of the rotating body 40.

■The magnetic pole change points that change from N pole to S pole in the reverse rotation direction of the motor are sequentially a1, a2, and so on. ....

When expressed as a12, the magnetic poles between the magnetic pole change point a1 and 812 exist at equal intervals, and the change points a12 and al
There is a change point a, / between which changes from the south pole to the north pole.

■The maximum value of the detected waveform of the magnetic flux density of the N pole adjacent to the magnetic pole change point a + / (the peak value where the output waveform changes from increasing to decreasing) is the maximum value of the detected waveform of the magnetic flux density of the other N pole of marker 41 smaller than the value and the magnetic pole change point a, L
The minimum value of the detected waveform of the magnetic flux density of the S pole adjacent to (the peak value at which the output waveform changes from decreasing to increasing) is larger than the minimum value of the detected waveform of the magnetic flux density of the other S poles of the marker 41.

That is, as shown in FIG. 6, in waveform A, which is the output (output of the differential amplifier 26) obtained by detecting the magnetization pattern of the marker 41 by the sensor unit 22, the detection ratio with respect to the magnetic flux density of the N pole of the marker 41 is Among the maximum values, the magnetic pole change point a,
The maximum value of the detection waveform for the magnetic flux density of the N pole adjacent to / is smaller than the maximum value of the detection waveform for the magnetic flux density of other N poles, and similarly, the detection for the magnetic flux density of the S pole of the marker Among the minimum values of the waveform, the minimum value of the detected waveform for the magnetic flux density of the S pole adjacent to the magnetic pole change point a, / is larger than the minimum value of the detected waveform for the magnetic flux density of the other S poles.

In addition, in order to satisfy the above conditions, in reality, for example, as shown in FIGS. 4 and 5(b) to 5(e),
The magnetic pole (N pole,
The width of a portion of the S pole is narrowed to reduce the area.

Note that the above two conditions (■) and (2) are required as the magnetization pattern of the marker 41, but among these conditions, (■) is especially required.
The conditions will be described in detail later. Further, the number of magnetic pole changing points may be three or more (a+ to a3).

Next, consider the conditions for rotating the driven motor in the forward direction.

Now, in the state shown in Fig. 4 or Fig. 5(b), if Im is flowed from I1 to E4 in the coil,
Since the coil pieces 11 and I3 face the north pole of the main magnetic pole 38, and the coil flies 2 and I4 face the south pole of the main magnetic pole 38, according to Fleming's left hand rule, the coil pieces I+
, 12 and 13 degrees I4 are each subjected to a force in the opposite rotation direction.

However, since the coil is fixed, the main magnetic pole 38 receives rotational force and rotates in the forward rotation direction. And rotor 3
9 exceeds the position shown in FIG. 5(C), all of the coil pieces 11 to 4 face the south pole, and no force is generated. Therefore, in order to obtain rotational force continuously, it is necessary to
), it is sufficient to switch the coil ■ so that the current flows in the direction from ■1 to ■4. Then, coil piece II1
．． I[3 faces the north pole, coil piece II2. I[4 is S
Since it faces the pole, the main pole 38 obtains a rotational force in the same way as described above. Similarly, when the rotor 39 reaches the position shown in FIG. 5(d), the current may be switched to the coil (2). Similarly, when the rotor 39 reaches the position shown in FIG. 5(e), the current may be switched to the coil I.The same applies hereafter.

That is, the position of the main magnetic pole 38 with respect to the coils 1 to
Figure 5 (b), (C), (d), (l), coil I, coil ■, coil ■2 coil E, respectively.
You can switch the current in the order of ・.

To do this, the sensor 25 detects the magnetic pole change point a12 in the state shown in FIG. The sensor 25 detects the magnetic pole change point a2 in the state shown in FIG. 5(d), passes a current through the coil ■, and the sensor 25 detects the magnetic pole change point a2 in the state shown in FIG. 5(e). Magnetic pole change point a
3 is detected and a current is made to flow through the coil 1.

The same applies below.

In addition, the main magnetic pole 38 of the rotor 39 is magnetized into 8 poles with N poles and S poles alternately spaced at equal intervals, and there are also 12 magnetic pole changing points a1 to a12 of the marker 41 at equal intervals, so that - Once the coils are rotated in the desired direction, the sensor 25 continuously detects the magnetic pole change points a1 to a and 2, and the drive currents of the coils 1 to 2 can be switched to rotate the coils.

In any case, the current switching points need to be the magnetic pole change points a1 to a12 of the marker 41.

By the way, since the magnetic pole changing points a1 to a12 are present at equal intervals, they can also be used as rotation speed information. That is, the above-mentioned FG multiplied signal is used. Further, as rotational phase information, it is necessary to detect a position of 11g during one rotation. In addition, in the motor drive device of the embodiment of the present invention described above, the magnetic pole change point of the marker 41 is set to the point a, /.

From the above, in the motor drive device according to the embodiment of the present invention, the output of the sensor 25 is input, and the magnetic pole change points a, L of the magnetic pole change points a1, a, /, a2 to a12 of the marker 41 are
a1, a circuit that extracts only the signal [PG signal] corresponding to
A circuit is required to extract only the signals [FG signals] corresponding to a2 to a12. This is the FG multiplied signal P which will be described later.
This is a G signal generation circuit.

Next, each component of the motor drive device of the present invention shown in FIG. 1 will be explained.

First, the sensor section 22 will be explained. When the rotor 39 is rotating in the forward rotation direction, the sensor (Hall element) 25 detects and outputs the magnetic flux density corresponding to the magnetic pole of the marker 41. The output of the sensor unit 22 (differential amplifier output) when the rotor 39 is rotating at a constant speed in the forward rotation direction is shown by output waveform A in the timing chart of FIG. That is, due to the conditions of the magnetization pattern of the marker 41 described above, this waveform A is at the magnetic pole change point a of the marker 41.
, the maximum peak value (maximum value) of the detected waveform corresponding to the magnetic flux density of the north pole bordering on l is higher than the maximum peak value (maximum value) of the detected waveform corresponding to the magnetic flux density of the other north pole of the marker 41. becomes smaller, and the minimum high value (minimum value) of the detection waveform corresponding to the magnetic flux density of the S pole bordering on the magnetic pole change point a, 1 of the marker 41 is the detection corresponding to the magnetic flux density of the other S pole of the marker 41. The output is made larger than the minimum peak value (minimum value) of the waveform.

FIG. 7 shows a block diagram of the FG double signal and PG signal generation circuit. Further, FIG. 8 shows a specific circuit example of the FG signal PG signal generation circuit shown in FIG. In FIGS. 7 and 8, the same components as in the previous figures are designated by the same reference numerals.

The output of the sensor section 22 (differential amplifier output) is input to comparators (level comparators) 27A, 278, and 270, respectively. The purpose of the comparator 27A is to detect all 1i pole changing points, and the voltage Va is set as the comparison input level to achieve this purpose. That is, in the timing chart of FIG.
The falling part of the output waveform B of 7A corresponds to the magnetic pole changes a II , a 12 , a + of the marker 41.

It exactly matches a2゜a3...

The comparator 27B also outputs a portion (marker 4) of the maximum value of the waveform A shown in FIG.
The comparison input level of the comparator 27B is set to the voltage Vc so as to detect only the N-pole portion adjacent to the magnetic pole change point a, I of 1). If the input level of the comparator 27B is larger than the voltage Vc, the output will be "H level", and if it is smaller, the output will be "L level", so the output waveform of the comparator 273 is as shown in the timing chart of FIG. , the waveform becomes like C.

The comparator 27C also outputs a portion of the minimum value of the waveform A shown in FIG.
The comparison input level of the comparator 27Q is set to the voltage Vo so as to detect only the S-pole portion adjacent to the magnetic pole change point a, I of 1). If the input level of the comparator 27C is greater than the voltage Vo, the output will be at the "high level", and if it is smaller than the voltage Vo, the output will be at the "H level". It becomes like ri.

Next, the output waveforms B, C, and D of these comparators 27A, 27B, and 27G are supplied to a digital signal processing circuit 28. Various methods can be considered for the circuit configuration of this digital signal processing circuit 28, but in short, using waveforms B, C, and D in FIG.
It is sufficient if a pulse with a timing corresponding to 12 and a pulse with a timing corresponding to the magnetic pole change point a + l of the marker 41 can be extracted.

That is, the falling part of the waveform B which is the output of the comparator 27A (indicated by O in FIG. 6) is at the magnetic pole change point aIs a2
+ .

There are various methods of extracting phase information (PG multiplied signal) using waveforms B, C, and D, examples of which are shown below.

Therefore, first, waveform 8. Using the three waveforms C and D, P
A method for extracting a G-times signal will be explained.

FIG. 8 shows a specific circuit example of the FG double signal and PG signal generation circuit 23 shown in FIG. This circuit will be explained below.

In FIG. 8, comparators 27A, 278, 270
As, a differential amplifier is used, and its output has waveforms B and C.

I got a D. Among them, comparator 27B and comparator 27
Waveforms C and D, which are the outputs of G, are input to the S terminal input and D terminal input of the R-S flip 70 tube 46, respectively. The R-S flip-flop 4G is set at the rising edge of the waveform C supplied to the S terminal input, and reset at the rising edge of the waveform C supplied to the R terminal input. Therefore,
The output waveform of the Q terminal of this RS flip-flop 4G is waveform E in FIG. This waveform E is input to the D@ terminal of an edge-triggered D flip-flop 47 with a reset terminal, and the waveform P, which is the output from the terminal of the R-8 flip-flop 46, is input to the R terminal of the D flip-flop 47 (reset terminal ) is entered.

Furthermore, the waveform B, which is the output of the comparator 27A, is input to the Ck terminal of the D flip-flop 47. And D.I.
When the main input is at "H level" and the R terminal input is at "L level", when a rising 0 pulse is input to the Ck terminal, the Q terminal output becomes "H level" and the R terminal input becomes "H". When the level reaches "'L level," the Q terminal output becomes "'L level." Therefore, the output waveform of the D flip-flop 41 is the sixth
The waveform is F in the figure. The timing of the rising edge of this waveform F (indicated by Δ in FIG. 6) coincides with the magnetic pole change point a,/ of the marker 41. In other words, this waveform F(
The signal) is a waveform (signal) having a pulse that is emitted once during one rotation of the motor, and is rotational phase information (PG multiplied signal).

Next, a method for extracting a PG multiplied signal using two waveforms B and D will be explained.

FIG. 11 shows a circuit that receives waveforms B, Tj, and D of FIG. 6 as input and outputs waveform F. That is, this circuit uses a shift register with a reset terminal. In this circuit, when the waveform n input to the DIR terminal is at "H level" and the waveform input to the R terminal is at "L level", the rising clock pulse input to the Cla terminal is When the power is turned on, the output Q2 becomes "H level". Then, when the R terminal input becomes "H level", it is reset and the output Q2 becomes "L level". Therefore, the output Q2 has waveform F. can get.

Alternatively, a counter shown in FIG. 12 may be used.

In this circuit, when the R terminal input is at "L level",
When two rising clock pulses of waveform B are input to the Ck terminal in succession, the output Q2 becomes "H level". Then, when the third clock pulse enters or the R terminal input becomes "H level", the output Q2 becomes "L".
level.

Here, the R terminal input becomes "H level" first.

Therefore, waveform F is obtained at output Q2.

In addition, as an example of a circuit that takes waveforms U, U, and D as input and outputs a waveform G (PG multiplied signal), there is a circuit shown in FIG. This circuit uses the same shift register as the circuit shown in Figure 11.
As a result, waveform G is obtained at output Q2.

Also in this case, the counter shown in FIG. 14 may be used as in FIG. 12. In this circuit, the same operation as in the circuit of FIG. 12 results in the waveform G being obtained at the output Q2.

Next, a method for extracting a PG multiplied signal using two waveforms B and C will be described.

Figure 15 shows the waveform B in Figure 6, and with C as input, the 6th waveform
This is a circuit that outputs the waveform H (PG times signal) shown in the figure, that is, it uses a shift register with a reset terminal like in Figure 11.In this circuit, the same operation as the circuit in Figure 11 is used. , after all, waveform 1'' is obtained at the output Q2.Also, in this case as well, the counter shown in FIG. 16 may be used as in FIG. 12.Then, the waveform H is obtained at the output Q2.

In addition, with waveform B, when C is input, waveform 1 shown in FIG.
There is a circuit shown in the figure. That is, this circuit uses a shift register with a reset terminal as in FIG. 11. In this circuit, the same operation as in the circuit of FIG. 11 results in waveform I being obtained at the output Q2.

Also in this case, the counter shown in FIG. 18 may be used as in FIG. 12. Then, a waveform I is obtained at the output Q2.

Here, in the circuit shown in FIG. 8, even if L is used for the waveform J shown in FIG. 6 instead of the waveform E obtained from the output Q of the R-S flip-flop 46, this R-
The operation of the D flip-flop 47 connected to the subsequent stage of the S flip-flop 4G remains unchanged, and as a result, the waveform F is obtained as the output Q of the D flip-flop 47. Therefore, in place of the R-S flip 70 tube 46 in the previous stage, by using the circuit shown below, the waveforms J and L may be created from the input waveform C1D.

First, there is a circuit shown in FIG. 19 as an example of a circuit that receives waveforms C and D as input and outputs waveform J. That is, this circuit uses a D flip-flop with a reset terminal. And in this circuit, D@
When the child large input is “H level”, the ROH child large input is “L level”
When a rising clock pulse is input to the Ck terminal, the output Q becomes "H level", and when the R terminal input is "H level", the output Q is reset and a waveform J is obtained at the output Q.

Further, as an example of a circuit that receives waveforms C and D as input and outputs waveform K, there is a circuit shown in FIG.

That is, this circuit has an OR circuit connected to the circuit of FIG. 19. In this circuit, the 19th
The output Q1 of the D flip-flop in the figure. : @ waveform J
By performing an OR gate with and waveform K, waveform K is obtained.

Further, as an example of a circuit that receives waveform C1D as input and outputs waveform [, there is a circuit shown in FIG.

In this circuit, if the waveform E obtained at the output Q of the R-8D flip-flop and the waveform are OR gated, the waveform is obtained.

Further, as a circuit for inverting the input waveform, an inverter shown in FIG. 22 is used.

Note that to obtain 0 at the waveform opening, the comparators 27A and 2 of FIG. 8 are used instead of using the inverter shown in FIG.
7B and 27G may be connected by reversing the "+" input terminal and the "-" input terminal as shown in FIG.

In the circuit shown in FIG. 8, instead of using the comparator 27B, the comparator 27C, and the R-S flip-flop 46 as a circuit for creating the waveform E, for example, a Schmitt trigger circuit shown in FIG. 24 may be used.

That is, in the Schmitt trigger circuit of FIG.
When the input signal ei is at a low level (before 1+) shown in FIG.
In this case, the input terminals A and B of the AND circuit are both at low level, and the output thereof is also at low level. Here, when the level of the input signal ei rises, the A side of the AND circuit simultaneously rises, and the B side rises by the voltage divided by the resistors R1, R2, and R3.

Therefore, the A side is the logic circuit's inversion threshold VT (→1.2
If the B side does not reach VT even after reaching V), the output eo
remains unchanged at low levels.

However, when the input signal level further increases and the B terminal reaches the threshold value VT (t2), the output eo is inverted to a high level (the input voltage value at this time is VH). Since this output is positively fed back to the 81st child through the resistor R3, the inversion of the output is instantaneously performed.

Next, when the input decreases, the AND circuit is inverted if even one input becomes low level, so at the moment (t4) when the A terminal falls below the threshold VT (input voltage value VL), the output eO is Switch to low level. At the same time, positive feedback occurs in resistor R3, and the reversal is instantaneous. Note that the hysteresis width is adjusted by the resistor R1.

FIG. 26 shows a circuit in which a diode D is connected, and the output feedback signal that has passed through the resistor Ra is shunted to the resistor R1, thereby preventing the feedback amount from decreasing. In the circuit shown in FIG. 27, the output signal eO is positively fed back to terminal B using an OR circuit.
Complete feedback is possible, and the feedback signal does not affect terminal A.

Therefore, the levels of VH and VL in Fig. 25 are set to 6.
Assuming Vc and Vo in the figure, the output (eO) becomes "H level" when the input level exceeds Vc, and becomes "L level" when the input level is lower than VD, as shown in Fig. 25. , in the end, waveform E is obtained.

Further, even when a Schmitt trigger circuit other than the one shown in FIGS. 24, 26, and 27 is used, the output waveform E can be obtained by setting the level similar to that described above.

In the circuit shown in FIG. 24, R1 is 100Ω, 4.7Ω, and R3 is 1Ω.

Further, instead of the @ magnetic pattern of the marker 41 shown in FIGS. 5 and 6, a magnetized pattern of the marker 41a shown in FIG. 28 may be used. That is, the following condition (■') is satisfied for the magnetization pattern of the marker 41 shown in FIG.

The magnetization pattern of the marker 41a shown in FIG. 28 satisfies (1)'. That is, ■' The magnetic pole change points that change from N pole to S pole in the reverse rotation direction of the motor are sequentially a1, a2, . ....

When expressed as a12, the magnetic poles between the magnetic pole change point a1 and 812 exist at equal intervals, and the change points a12 and al
There is a change point a + 1 between the S pole and the N pole, and between the change points a1 and a2 there is a change point a2', which changes from the S pole to the N pole, and the change point a2 and S between a3
There is a change point a3J that changes from a pole to a north pole, and between change points a3 and a4 there is a change point a4 that changes from a south pole to a north pole.
′ exists.

■'Magnetic pole change point a+', a21, a3(.

The maximum value of the detected waveform of the magnetic flux density of the N pole adjacent to each of a 4/ (the peak value where the output waveform changes from increasing to decreasing) is greater than the maximum value of the detected waveform of the magnetic flux density of the other N pole of marker 41a. If it's small too! Change point a! ' , a2'
The minimum value of the detected waveform of the magnetic flux density of the S pole adjacent to each of l as' and a t' (the peak value at which the output waveform changes from decreasing to increasing) is the detected waveform of the magnetic flux density of the other S pole of Mar 71418 be larger than the minimum value of .

That is, as shown in FIG. 28, the output (differential amplification signal 2
In the waveform A' which is the output of No. 6), the magnetic pole change points a, l, a21, a3f among the maximum values detected for the magnetic flux density of the N pole of the marker 41a.

The maximum value of the detected waveform for the magnetic flux density of the N pole adjacent to each of a 4T is smaller than the maximum value of the detected waveform for the magnetic flux density of the other N pole, and similarly, the magnetic flux of the S pole of the marker 41a Among the minimum values of the detected waveform with respect to the density, ta pole change point a1'.

a2', a3', a4' (7) Each adjacent S
The minimum value of the detected waveform for the magnetic flux density of the pole is larger than the minimum value of the detected waveform for the magnetic flux density of the other S poles.

In the figure, especially the magnetic pole change point a1'.

The fa poles (
By narrowing the width (magnetized area) of the N pole and S pole, the detected waveform satisfies the above conditions. The output waveform obtained from the marker 41a at this time is A'
becomes. Furthermore, each comparator 27A.

The output waveforms of 27B and 27C are waveform 31, respectively.
It becomes like C/ or D'.

Note that the timing of the falling part of this waveform B' (28th
The velocity information (indicated by the O mark in the figure) is obtained as a signal multiplied by FG.

In this way, like the marker 41a, IN! When a pattern is applied, the detected waveform is used as input to create a circuit similar to that of the above embodiment, for example, waveforms TJ(Ill'), C(C'>, C(C') as shown in FIG.
) is used as an input, the operation of the shift register described above produces a waveform C+ (PG times signal) shown in FIG. 28 at the output Q2 of this shift register.

Furthermore, if the counter shown in FIG. 18 is used, the output Q2 of this counter will have the waveform C2 shown in FIG. 28, the output Q3 will have the waveform C3, the output Q4 will have the waveform C4, and the output Q5 will have the waveform C2 shown in FIG. It can be seen that waveforms C5 are obtained, and these waveforms (pulses) become phase information (PG multiplied signal).

Similarly, if the shift register shown in FIG. 15 is used, by inputting the waveforms B', c', and C', the waveform C6 shown in FIG. 28 will be obtained as the output Q2 of this shift register.

In addition, if a size counter is used in FIG. 16, the waveform B'
, C' as inputs, the output Q2 of this counter is a waveform C7, the output Q3 is a waveform CB, the output Q4 is a waveform C9, and the output Q5 is a waveform C+.

are obtained respectively.

In this way, all of the circuits used in the above embodiments can also be used for the waveform that detected the magnetization pattern of the marker 41a shown in FIG. 28, and phase information (PG multiplied signal can be obtained.

Furthermore, the timing relationship between the respective waveforms shown in FIG. 28 above is exactly the same as the timing relationship between the waveforms shown in FIG. Therefore, even with the magnetization pattern of the marker 41a as shown in FIG. 28, there is no problem in the operation of the apparatus of the present invention.

Furthermore, instead of the magnetization pattern of the marker 41 shown in FIGS. 5 and 6, a magnetization pattern of the marker 41b shown in FIG. 29 may be used. That is, the marker 41 shown in FIG.
The magnetization pattern of the marker 41b shown in FIG. 29 is a magnetization pattern that satisfies the following conditions (2) and (2) with respect to the magnetization pattern. In other words, ■''The magnetic pole change points that change from N pole to S pole in the direction of reverse rotation of the motor are sequentially set to al+.
a2. ....

When expressed as a12, the magnetic poles between the magnetic pole change point a1 and 812 exist at equal intervals, and the change points a12 and al
There is a change point a, l that changes from the S pole to the N pole between the change points a1 and a2, and a change point a2J that changes from the S pole to the N pole exists between the change points a1 and a2, and the change points a2 and a3 There is a change point a 3/ between the S pole and the N pole,
. . . Between the changing point a II and 812, there is a changing point a12' that changes from the S pole to the N pole.

■“Magnetic pole changing point a , / , a 2 + , a
3+, .

The maximum value of the detected waveform of the magnetic flux density of the N pole adjacent to each of a11' (the peak value where the output waveform changes from increasing to decreasing)
is smaller than the maximum value of the detected waveform of the magnetic flux density of the other N pole of the marker 41b, and the magnetic pole change point a, / , a2 /
, a', . Greater than the minimum value of the density detection waveform.

This condition ■'' is the same as the following: In other words, the maximum value of the detected waveform of the magnetic flux density of the N pole adjacent to the magnetic pole change points a and 2' (the peak value where the output waveform changes from increasing to decreasing) are the magnetic pole change points a+' and a2 of the marker 41b
'+83' *..., larger than the maximum value of the detected waveform of the magnetic flux density of the other N poles adjacent to each of 'all',
In addition, the minimum value of the detected waveform of the magnetic flux density of the S pole adjacent to the magnetic pole changing point a12' (the peak value at which the output waveform changes from decreasing to increasing) is at the magnetic pole changing point a of the marker 41b, /
, a21, a3/.

. . . be smaller than the minimum value of the detected waveform of the magnetic flux density of the other S poles adjacent to each of all'.

That is, as shown in FIG. 29, the output (differential amplifier 2
In the waveform A'' which is the output of No. 6), among the detected maximum values for the magnetic flux density of the N pole of the marker 41b, the maximum value of the detected waveform for the magnetic flux density of the N pole adjacent to the magnetic pole change point a12' is the magnetic pole change. Point a, /l a21, a3'
, . Among the minimum values, the minimum values of the detected waveform for the magnetic flux density of the S pole adjacent to the magnetic pole change point a12' are the magnetic pole change points a1', a2', a3', ..., all'
is smaller than the minimum value of the detected waveform with respect to the magnetic flux density of the other S poles adjacent to each of the S poles.

In the figure, especially the magnetic pole change point 81'.

By narrowing the width (magnetized area) of the magnetic poles (N pole, S pole) adjacent to each of a 21 , a 3', ...+aII', the detected waveform satisfies the above conditions. ing. The output waveform obtained from the marker 41b at this time is A II. Furthermore, each comparator 27A, 2
The output waveforms of 7B and 27G are each waveform B''.

It becomes like C", D".

Note that the timing of the falling part of this waveform B'' (29th
Speed information (FG multiplied signal) is obtained in the figure (indicated by O in the figure).

In this way, when a magnetized pattern is applied like the marker 41b, it is possible to obtain phase information (PG multiplied signal) by using the detected waveform as an input and using a circuit similar to the above-described embodiment. Of course, it is also possible to obtain phase information (PG multiplied signal) using a circuit other than the one shown in this embodiment.

Therefore, first, a circuit that receives waveforms 3H and CII as input will be described.

FIG. 30 shows a circuit that takes the waveforms 'g n and CII as input and outputs the waveform E'' (PG multiplied signal, that is,
This circuit uses an R-S flip-flop. In this circuit, the waveform C'n input to the S terminal is
The waveform TJ is set at the rising edge of TJ and is input to the R terminal.
It is reset at the rising edge of n. Therefore, a waveform E II is obtained at the output Q.

In FIG. 31, the waveform of the S terminal input and the waveform of the R terminal input in FIG. 30 are exchanged. In this circuit, due to the same operation as described above, the waveform F is output to the output Q.
”(PG multiplied signal is obtained.

Next, a circuit that receives waveforms B" and D" as input will be described.

FIG. 32 shows a circuit which takes the waveforms U JJ and DII as input and outputs the waveform G" (PG multiplied signal. In other words, this circuit uses an R-S flip-flop. In this circuit, the above-mentioned By the same operation as above, the waveform G o is finally obtained at the output Q.

FIG. 33 is a diagram in which the waveform of the S terminal input and the waveform of the R terminal input in FIG. 32 are swapped. In this circuit, due to the same operation as described above, the waveform H is output to the output Q.
“(PG multiplied signal is obtained.

From the above, if the @magnetic pattern of the marker, which is the detected part, satisfies the following conditions (n) and (n), there will be no problem in the operation of the device of the present invention. That is, the magnetic pole change points where the magnetic pole changes from N1M to S pole in the reverse rotation direction of the n motor are sequentially a1, a2, . ....

When expressed as an (where n is an integer of 3 or more), the magnetic poles between this magnetic pole change point a1 and an exist at equal intervals, and the magnetic pole changes from the S pole to the N pole between the change points an and al. There is a change point al' between change points a1 and a2, and a change point a2' that changes from the S pole to the N pole, and the change point a2
There is a change point a3' between and a3 that changes from the S pole to the N pole, ..., between the change points a old and an
There is a turning point an' that changes to a pole.

■n Magnetic pole change point a H', a2' r 83',
a, l, a 21, a of +anl
3', .

The maximum value of the detected waveform of the magnetic flux density of the N pole adjacent to each of ar' (where r is an integer of 1≦r<n) (the peak value where the output waveform changes from increasing to decreasing) It is smaller than the maximum value of the detected waveform of the magnetic flux density of the N pole, and is at the magnetic pole change point a1'.

a 21 , a , T,..., 8 of a nl
1′.

The minimum value of the detected waveform of the magnetic flux density of the S pole adjacent to each of a2', a3' + "'* a1' (the peak value at which the output waveform changes from decreasing to increasing) is the marker 41a.
be larger than the minimum value of the detected waveform of the magnetic flux density of the other S poles.

Note that, in the present invention, as in each of the above embodiments, the marker 41.
41a, 41b1. : It is not limited to the one in which a magnetized pattern is applied and this magnetized pattern is detected by the sensor 25, but for example, the magnetized pattern in which two types of materials with different reflectances are applied to the marker 41 described above is distribute,
This may be detected using a sensor (such as a photoreflector) that detects linear reflectance.

Furthermore, regarding the magnetization patterns applied to the markers 41, 41a and 41b, even if the positions of the N and S poles are exchanged for each magnetic pole (N and S poles), there will be no difference in the operation of the device of the present invention. do not have. That is, the output waveform of the detected magnetization pattern in which the positions of the N and S poles are exchanged is transmitted to the sensor unit 22, for example.
If the polarity is reversed by connecting the "+" input terminal and "-" input terminal of the differential amplifier 26 in reverse,
An output waveform such as waveform A shown in FIG. 6 is obtained.

As described above, the embodiments of the present invention provide a PG head for detecting phase information of a rotating drum, a corresponding FG head for detecting speed information of a rotating drum with a detected magnetic pole, and a corresponding PG head for detecting phase information of a rotating drum in a conventional device. In addition, in order to switch the drive current of the motor, for example, in the case of an m-phase Hall motor, the Hall element is
These functions can now be realized with one marker (detected magnetic pole) and one sensor, whereas the number of parts used to be required is reduced. Therefore, the number of parts is reduced and assembly of the device becomes easier.

(Effects of the Invention) As described above, according to the motor drive device of the present invention, the changing points a+', a2' * 83', ... a n',
of a I' * a2' , a3' *...,
The maximum value of the detected waveform of one of the two physical quantities adjacent to each of a' (where r is an integer of 1≦r<n) is greater than the maximum value of the detected waveform of the other physical quantity. is also small, and the change points a, T, a2T.

a, l, of a3',... anl,
a21゜a3',...a so that the minimum value of the detected waveform of the other of the two physical quantities adjacent to each of r+ is larger than the minimum value of the detected waveform of the other physical quantity. A rotation detection pulse obtained from a sensor section having one detected section and one sensor corresponding thereto generates a current to flow through the coils of each phase, and also makes it possible to extract rotation phase information and rotation speed information. Because of this, the number of parts can be reduced compared to conventional devices, which allows easy wiring and inexpensive construction, and further improves productivity.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a motor drive device according to the present invention, FIG. 2 is a block diagram showing an embodiment of the device according to the present invention, and FIGS. 3 and 4 are diagrams showing the structure of a driven motor. FIG. 5 is a diagram illustrating the movement of the magnetic pole of the rotor of the driven motor relative to the coil. FIG. 6 is an embodiment of the device of the present invention shown in FIGS. 2, 7, and 8. Figure 7 is a block diagram showing the FG double signal and PG signal generation circuit, and Figure 8 is the FG double signal and PG signal generation circuit in Figure 7. 9 is a block system diagram showing an example of a conventional motor drive device, FIG. 10 is a signal waveform diagram for explaining the operation of the conventional device shown in FIG. 9, and FIG. 11 is a diagram showing a specific circuit example of the circuit. ~Second
4, FIG. 26, FIG. 27, and FIGS. 30 to 33 are circuit diagrams showing some modified examples of the circuit in FIG. 8, and FIG. FIGS. 28 and 29 are signal waveform diagrams for explaining the operation of the circuit shown in the figure, and are diagrams showing other embodiments of the magnetization pattern of the marker constituting the apparatus of the present invention and their signal waveforms. 21... Marker section, 22... Sensor section, 23...
FG double signal and PG signal generation circuit, 24... Motor drive circuit, 25... Sensor, 26... Differential amplifier, 27
A, 27B, 27G... Comparator, 28... Digital signal processing circuit, 29... Pulse generation circuit, 30... Switch circuit means, 31... Waveform conversion circuit, 32... Driver circuit , 33... Retriggerable mono multi, 34... Changeover switch, 36... Ring counter,
37... Waveform conversion logic circuit, 38... Main magnetic pole, 39
...Rotor, 40-...Rotating body, "41.418.4
1b-v-force, 42... Stator, 43... Shaft, 44... Rotating drum, 45a, 45b... Video head, 46... R-S flip-flop, 47... D flip flop. Running 1 Figure Chi 3rfJ n Kaya 4L5E1 o-111111111111111. , ) 5 figures, ! l-7 sides ÷ 11 cheers +! 50 outside 12 figure 1
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Claims (1)

[Claims] Two types of physical quantities are alternately provided on the circumference of a rotating body provided on the rotor of a motor to be driven having an m-phase coil (where m is an integer of 2 or more), and The points at which one of these two physical quantities changes from one to the other are sequentially a_1, a_2, ..., a_n (where n is 3
(integer greater than or equal to)), and the physical quantities from the changing points a_1 to a_n are made to exist at equal intervals, and the changing points a_n and a_1
Let a_1' be the change point where the physical quantity changes from the other physical quantity to one physical quantity that exists between the change points a_1 and a_2, and let a_2' be the change point that exists between the change points a_1 and a_2 where the other physical quantity changes to the one physical quantity. , the change point where the other physical quantity changes to one physical quantity existing between the change points a_2 and a_3 is a_3',..., the change points a_n_-_1 and a
Let a_n' be the change point at which one physical quantity changes from the other physical quantity existing between _n, and these change points a_1'
, a_2', a_3', ..., a_n'.
1', a_2', a_3', ..., a_r' (where r is an integer of 1≦r<n), the maximum value of the detected waveform of one of the two physical quantities adjacent to each of is smaller than the maximum value of the detected waveform of the other physical quantity,
And the changing points a_1', a_2', a_3',...
of a_n', a_1', a_2', a_3',...
・One detected object in which the minimum value of the detected waveform of the other of the two types of physical quantities adjacent to each of the two types of physical quantities adjacent to each of , a_r' is larger than the minimum value of the detected waveform of the other physical quantity. a sensor unit having a sensor for detecting a physical quantity of the detected unit; and a sensor unit having a sensor for detecting a physical quantity of the detected unit, and the detected unit whose driving current to be applied to the m-phase coil of the motor to be driven is to be switched based on a detection signal from the sensor unit. a rotation detection signal with a phase related to the physical quantity position of the part and a repetition frequency proportional to the rotational speed of the rotating body, and a phase related to the physical quantity position of the detected part, and
a detection signal generation circuit that outputs a pulse phase detection signal corresponding to the rotational phase of the rotating body; and a detection signal generation circuit that is supplied with the rotation detection signal of the detection signal generation circuit to create a rotating magnetic field for rotating the rotor. A motor drive device comprising a motor drive circuit that generates a target m-phase drive pulse and outputs it to the m-phase coils as separate drive currents.