JPH05137396A - Drive motor controller - Google Patents

Abstract

PURPOSE:To realize highly accurate constant speed operation of drive motor. CONSTITUTION:A drive motor, i.e., a scan motor, comprises stator and rotor having structures similar to those of hybrid permanent magnet type step motor. A basic pattern generating circuit 48 generates basic cosine wave pattern PC and basic sine wave pattern PS based on a frequency control clock signal FCK fed from a frequency control clock forming unit 47, while furthermore correction patterns PHC, PHS for offsetting detent torque produced due to magnetic inbalance between rotor and stator are generated based on a position detection signal SC fed from a rotational position detecting circuit 50 and the frequency control clock signal FCK. A drive circuit 36 then performs conduction/ interruption control of phase A coil 26A and phase B coil 26B in stator coils based on a current pattern combining the basic patterns PC, PS and the correction patterns PHC, PHS.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive motor control apparatus suitable for operating a load of a dry copying machine or a printer in a forward direction with a high precision and a constant speed.

[0002]

2. Description of the Related Art For example, an optical system scanner section of a dry copying machine drives a first carriage having an exposure lamp and a reflection mirror and a second carriage having a reflection mirror.
The scan motor, which is a barrel, moves the document from the home position through the belt transmission mechanism to scan the document, and then reverses the scan motor to move the first and second carriages back. It is configured to return to the home position.

In this case, as the scan motor, in order to change the copy magnification, it is necessary that the speed can be changed during the forward movement of the carriage in order to change the scan speed according to the copy magnification. In order to improve the image quality of the copy, it is required to rotate the carriage at a constant speed as small as possible when the carriage is moving forward.

Therefore, conventionally, a stepping motor or a brushless motor is used as the scan motor.

When a stepping motor is used, when the carriage is moving forward, a pulse power having a constant frequency is applied to operate as a synchronous motor, and when the copying magnification is changed, the operating frequency of the pulse power is changed. When the carriage is moved back, the pulse power phases are reversed to reverse the pulse power rate, and the pulse power rate is patterned to return to the home position in the shortest time.

Further, a brushless motor is used as a scan motor.
In the case of using a motor, especially when the carriage is moving forward, the operation is performed by a phase lock loop (PLL) control or the like in order to obtain a constant speed rotation.

[0007]

In the former case where the stepping motor is used as the scan motor, the pulse power peculiar to the stepping motor is given even if the carriage is required to rotate at a constant speed when the carriage moves forward. Rotational vibrations due to the overshoot when stepping each time it is run greatly affect the image quality, especially when operating at low frequencies.

Further, a brushless motor is used as a scan motor.
In the latter case of using a rotor, if the carriage is rotated at a low speed when the carriage moves forward, the flywheel effect of the rotor cannot be expected, so unstable operation is likely to occur.

Particularly, in a color copying machine, since four exposures are performed in one copy to synthesize toners of four colors, unevenness in rotation of the scan motor leads to color misregistration of the copy. Since the range of copying magnification has been widened recently, color unevenness becomes conspicuous when the copying magnification is high, and there is a demand for highly accurate constant speed operation of the scan motor.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a drive motor control device capable of controlling a highly accurate constant operation of a drive motor.

[0011]

A drive motor control apparatus according to the present invention comprises a stator having a plurality of small tooth magnetic poles formed on a tooth portion around which a plurality of phases of stator coils are wound, and a large number of small teeth on the outer circumference. The first magnetic pole is formed and magnetized to the N pole
A rotor having a second rotor portion magnetized to an S pole, in which a large number of small tooth magnetic poles shifted by 1/2 pitch from the small tooth magnetic poles of the rotor portion are formed on the rotor portion and the outer periphery thereof. Using a drive motor equipped with a position detecting means for outputting a position detecting signal having a constant phase difference with the induced voltage of the stator coil, and providing a basic pattern generating means for generating a basic pattern of current, Correction pattern generating means for generating a correction pattern of a current for canceling detent torque caused by magnetic imbalance between the rotor and the stator based on the position detection signal of the position detecting means is provided, and the basic pattern and the correction pattern are combined. A pattern synthesizing means for generating a current pattern is provided, and a drive means for controlling the stator coil to be turned on and off based on the current pattern from the pattern synthesizing means. Configuration has a feature.

[0012]

According to the drive motor controller of the present invention, since the stator and rotor of the drive motor have the same structure as that of the hybrid permanent magnet type stepping motor,
It can be operated as a hybrid permanent magnet type stepping motor with less rotational vibration and rotational unevenness.
The stator coil is controlled to switch on and off based on a current pattern obtained by combining a basic pattern of current with a correction pattern for canceling detent torque caused by magnetic imbalance between the rotor and the stator. Driving becomes possible.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a dry copying machine will be described below with reference to the drawings.

First, the dry copying machine 1 will be described with reference to FIGS.
The configuration of will be described. Reference numeral 2 denotes a machine frame, inside of which a first carriage 5 having an exposure lamp 3 and a reflection mirror 4 and a second carriage 8 having reflection mirrors 6 and 7 are provided in the direction of arrow Q and It is provided so that it can move back and forth in the opposite direction. Further, a drum 9 which is a photoconductor is arranged in the machine frame 2, and the drum 9 is rotated at a constant speed in a direction of an arrow R by a driving motor (not shown).

Further, in the machine frame 2, a lens unit 11 having a lens 10 and a reflection mirror unit 14 having reflection mirrors 12 and 13 are arranged, and a fixed reflection mirror 15 is arranged. There is. A glass plate 17 on which the document 16 is placed is attached to the upper opening of the machine frame 2. In this case, the light from the exposure lamp 3 of the first carriage 5 is reflected from the original 16 on the glass plate 17, and further reflected by the reflection mirrors 6 and 7 of the second carriage 8, and the light of the lens unit 11 is reflected. Passing through the lens 10,
It is reflected by the reflection mirrors 12 and 13 of the mirror unit 14, and finally by the fixed reflection mirror 15 and then the drum 9
It is supposed to be exposed on top.

Reference numeral 18 denotes a scan motor which is a drive motor, and the forward and reverse rotations are transmitted to the carriages 5 and 8 as a reciprocating movement via a belt transmission mechanism 19. That is, the belt transmission mechanism 19 includes a pulley 20 rotated by the scan motor 18 and a plurality of pulleys arranged on the machine frame 2.
It is constituted by a belt 21 and a belt 22 hung on these pulleys 20, 21, and a portion 22a of the belt 22 is connected to the first carriage 5 and a portion 22b.
Is connected to the second carriage 8 and the scan mode is
When the motor 18 is rotated in the normal direction, for example, the first carriage 5 is moved in the direction of arrow Q and the second carriage 8 is moved in the direction of arrow Q at a speed half that of the first carriage 5. It is like this.

Therefore, if the second carriage 8 is moved in the direction of arrow Q by a distance L as shown in FIG.
The first carriage 5 is moved in the same direction by a distance 2L. This relationship is maintained even when the scan motor 18 is reversed and the carriages 5 and 8 are moved in the direction opposite to the arrow Q.

The dry copying machine 1 has a function of changing the copying magnification. That is, as the copy magnification, the lens unit 11 and the mirror unit 14 are moved in the direction of the arrow in FIG. 3 to specify the route distance La from the lens 10 to the original 16 and the route distance Lb from the lens 10 to the drum 9 to the designated magnification. This is achieved by setting the ratio and changing the speed of the scan motor 18 according to the designated magnification ratio.

Next, the scan mode will be described with reference to FIGS.
The configuration of the data 18 will be described. The scan motor 18 has a structure similar to that of a two-phase hybrid permanent magnet type stepping motor.

That is, 23 is a frame in which a stator 24 is fitted and fixed. This status 2
In No. 4, a four-phase stator coil 26 is wound around an even number of teeth portions 25, and each teeth portion 25 is formed with a plurality of small tooth magnetic poles 25a.

27 is a rotor, which is a shaft 28
First and second rotor parts 29 and 30 fitted and fixed to the
And a tee on the outer circumference of the first rotor portion 29.
A large number of small tooth magnetic poles 29a having the same pitch as the small tooth magnetic poles 25a of the tooth portion 25 are formed. A large number of small tooth magnetic poles 30a are formed. Further, a permanent magnet 31 having both shaft ends as N poles and S poles is interposed between the first and second rotor portions 29 and 30, so that the first rotor portion 29 is To the N pole and the second rotor part 3
0 is magnetized to the south pole. The rotor 27 thus constructed is disposed in the hollow portion of the stator 24, and both ends of the shaft 28 thereof are supported by bearings 32, 32 provided on the frame 23.

Reference numeral 33 is a printed wiring board arranged in the frame 23, and has two position detecting elements 34 and 35, which are the same in number as the number of phases of the stator coil 26 serving as position detecting means. The rotor portion 29 is attached so as to correspond to the small tooth magnetic pole 29a. In this case, the position detecting element 3
Reference numerals 4 and 35 are magnetic sensors such as hole elements and hole ICs, and as will be described later, they have an integral multiple of an electrical angle π / 4, for example, an angle of π / 2, which will be described later. Each A,
This is for outputting the position detection signals SA and SB (see FIG. 11) having a π / 4 delay phase with respect to the negative half waves of the B-phase induced voltages VA and VB.

The configuration of the control device for the scan motor 18 will be described with reference to FIG.

Reference numeral 36 denotes a drive circuit having a two-phase bipolar structure as a drive means, which controls the A-phase coil 26A and the B-phase coil 26B of the starter coil 26 to switch on and off. The A-phase coil 26A will be described.

Reference numeral 37 is a power supply terminal connected to the positive terminal of the DC power supply, and the negative terminal of the DC power supply is grounded. 38A and 39A are PNP type transistors, each emitter is connected to the power supply terminal 37, and each collector is connected to each collector of NPN type transistors 40A and 41A. The emitters of the transistors 40A and 41A are commonly connected, and the common connection point is grounded via the current detection resistor 42A. The A-phase coil 26A is connected between the collectors of the transistors 38A and 39A. 43A and 44A are flywheel diodes connected between the collectors of the transistors 40A and 41A and the ground.

The above is a description of the configuration relating to the A-phase coil 26A, but the configuration relating to the B-phase coil 26B is also the same, and the same parts are denoted by the suffix "B" instead of the suffix "A". Attached and shown.

Reference numeral 45 denotes a microcomputer as a control means, which outputs the selection signal S1 for selecting the motor operation mode, that is, the stepping motor operation mode or the brushless motor operation mode, and the magnitude of the stator coil current. It has an output port O2 for outputting a current command signal S2 to be set and an output port O3 for outputting a frequency command signal S3 for setting the number of rotations in the stepping motor operation mode, and also has a rotation signal as described later. It has an input port I to which S4 is provided.

Reference numeral 46 is a basic clock generator, the output terminal of which is the input terminal I1 of the frequency control clock generator 47.
It is connected to the. This frequency control clock generator 47
Has its input terminal I2 connected to the output port O3 of the microcomputer 45,
The basic clock signal from 6 is appropriately frequency-divided based on the frequency command signal S3 and output as the frequency control clock signal FCK. The output terminal of the frequency control clock generator 47 is connected to the input terminal I of the basic pattern generating circuit 48, which is the basic pattern generating means, and the input terminal I1 of the correction pattern generating circuit 49, which is the correction pattern generating means. Has been done.

Here, the basic pattern generation circuit 48 outputs the basic cosine wave pattern PC shown in FIG. 7B from the output terminal O1 on the basis of being supplied with the frequency control clock signal FCK shown in FIG. 7A. In addition to outputting, the basic sine wave pattern PS shown in FIG. 7C is output from the output terminal O2. In addition, the auxiliary pattern generation circuit 49 is connected to the output terminal O1 from the output terminal O1 as shown in FIG.
While outputting the correction pattern PHC shown in (e),
From the output terminal O2 to the correction pattern PHS shown in FIG.
Is to be output.

Numeral 50 is a rotational position detecting circuit which is a position detecting means, and its input terminals I1 and I2 are position detecting elements 34.
And 35. This rotational position detection circuit 50
Waveform-shapes the signals from the position detection elements 34 and 35, and outputs the rectangular-wave position detection signals SA and SB and SC shown in FIGS. 11B and 11C and FIG. 8B to the output terminals O1 and It is output from O2 and O3. The rotational position detection circuit 50 also detects the position detection signals SA and S.
A rotation signal S4 indicating rotation position information, rotation speed information, and rotation direction information is obtained from B and is output from the output terminal O4.

In the rotational position detecting circuit 50, its output terminals O1 and O2 are drive signal forming circuits 51.
Of the correction pattern generating circuit 49, and the output terminal O4 is connected to the input port I of the microcomputer 45.
It is connected to the. In this case, the drive signal forming circuit 51
Drive signals A +, B +, A- and B- are output from the output terminals O1, O2, O3 and O4 as described later.

Reference numeral 52 is a stepping-brushless selection circuit which is a pattern synthesizing means, its input terminal I1 is connected to the output port O1 of the microcomputer 45, and its input terminals I2 and I3 are the output terminals O1 and O2 of the basic pattern generation circuit 48. Input terminals I4 and I5 are connected to output terminals O1 and O2 of the correction pattern generating circuit 49, and input terminals I6 to I9 are connected to the drive signal forming circuit 51.
Of the output terminals O1 to O4.

Here, the stepping-brushless selection circuit 52 outputs the signals given from the output terminals O1 and O2 to the input terminals I2 to I5 or the input terminal I6 according to the content of the selection signal S1, as described later. Through I9
To output the signal applied to the output terminals O1 and O2 of the multipliers 53A and 53A.
B is connected to each input terminal I1.

The input terminals I2 of the multipliers 53A and 53B are connected to the output port O2 of the microcomputer 45, and the signal supplied to the input terminal I1 is multiplied by the current command signal S2 to generate a current setting signal. It is designed to be output as. And these multipliers 53
The output terminals of A and 53B are the current control circuits 54A and 5A.
4B is connected to each input terminal I1.

In this current control circuit 54A, its input terminal I2 is connected to the common connection point of the emitters of the transistors 40A and 41A, and its output terminals O1, O2, O3 and O4 are transistors 38A, 39A, 40A and 41A.
Is connected to each base of. Similarly, in the current control circuit 54B, the input terminal I2 is connected to the transistor 40
B, 41B are connected to a common connection point of the emitters, and output terminals O1, O2, O3 and O4 are connected to transistors 38B, 3
9B, 40B and 41B are respectively connected to the respective bases. In this case, the current control circuits 54A and 54B switch the respective transistors so that the signal applied to the input terminal I2 follows the current setting signal applied to the input terminal I1.

Next, the operation of this embodiment will be described with reference to FIGS.
The description will be made with reference to FIG.

When the operating unit (not shown) is operated to set the copy magnification, the microcomputer 45 sets the selection signal S1 to the stepping motor operation mode to rotate the scan motor 18 from the copy magnification. The speed is determined, the frequency command signal S3 corresponding to this is output, and the current command signal S2 suitable for the operation is output.

As a result, the frequency control clock forming circuit 47 comes to output the frequency control clock signal FCK corresponding to the frequency command signal S3, and the reference pattern generating circuit 48 outputs the frequency control clock signal FCK according to the frequency control clock signal FCK. 7 (b) and (c), the basic cosine wave pattern PC
And a basic sine wave pattern PS are output.

Further, since the selection signal S1 indicating the stepping motor operation mode is given to the stepping-brushless selection circuit 52, the selection circuit 52 first selects the stepping motor operation mode, and the input terminal I2 is selected.
And the basic cosine wave pattern PC and the basic sine wave pattern PS given to I3 are output from the output terminals O1 and O2, respectively. Further, the multipliers 53A and 53B multiply the basic cosinusoidal wave pattern PC and the basic sine wave pattern PS by the current command signal S2 and output the result as a current setting signal.

Then, the current control circuit 54A causes the transistors 38A and 4A so that the current flowing through the A-phase coil 26A follows the current setting signal based on the basic cosine wave pattern PC.
1A, 39A and 40A are turned on and off. In this case, during the positive half-wave period of the basic cosine wave pattern PC, the transistor 41A remains on and the transistor 38A repeatedly turns on and off by PWM control.
In the negative half-wave period of the basic cosine wave pattern PC,
Transistor 40A remains on and transistor 39A
Is repeatedly turned on and off by PWM control.

Similarly, the current control circuit 54B causes the transistors 38B, 4 so that the current flowing through the B-phase coil 26B follows the current setting signal based on the basic sine wave pattern PS.
1B, 39B and 40B are turned on and off. In this case, during the positive half-wave period of the basic sine wave pattern PS, the transistor 41B remains on and the transistor 38B repeatedly turns on and off by PWM control.
In the negative half-wave period of the basic sine wave pattern PS,
Transistor 40B remains on and transistor 39B
Is repeatedly turned on and off by PWM control.

As a result, the scan motor 18 is microstepped as a stepping motor to rotate at a set constant speed, and the carriages 5 and 8 are moved in the direction of arrow Q from the home position shown by the solid line in FIG. Thus, the drum 9 is exposed.

In the scan motor 18, when the motor coil 26 is cut off, the rotor 27 is set to N
A detent torque for stopping and holding at a fixed position is generated by one magnetic force and the other magnetic force of the small tooth magnetic pole 29a of the first rotor portion 29 of the pole and the small tooth magnetic pole 30a of the second rotor portion 30 of the S pole. To do. Therefore, even when the motor coil 26 is energized to rotate the rotor 27, the rotor 2
7. A detent torque generated by the magnetic imbalance acts between the stator 23 and the stator 23, which causes a slight rotation unevenness in the rotation of the rotor 27.

Therefore, in this embodiment, the correction pattern generating circuit 49 and the rotational position detecting circuit 50 operate as follows.

That is, in accordance with the rotation of the rotor 27, induced voltages VA and VB are generated in the A-phase coil 26A and the B-phase coil 26B as shown in FIG. Outputs a position detection signal, and the rotational position detection circuit 50 generates position detection signals SC and SD based on this. In this case, the position detection signal SC is set so as to have a constant phase difference with respect to the induced voltages VA and VB. Here, for example, as shown in FIG. 8B, the rising edge of the position detection signal SC is set so as to coincide with the zero-cross point of the induced voltage VA from positive (+) to negative (-).

Then, the correction pattern generation circuit 49 uses the position detection signal SC shown in FIG. 8B and the frequency control clock signal FCK shown in FIG. 8D to determine the small teeth of the first rotor portion 29. With respect to the magnetic force of the magnetic pole 29a and the small tooth magnetic pole 30a of the second rotor portion 30, a detent torque that acts in the direction of magnetic force and a detent torque that acts in the direction of rotation is applied to the magnetic pole portion of the detent torque that acts in the counter-rotational direction of the rotor 27. The correction patterns PHC and PHS shown in FIGS. 8 (e) and 8 (f) for flowing a current in the direction of decreasing the magnetic force are output to the magnetic pole portion of FIG.

Stepping-brushless selection circuit 52
Is a combination of the basic cosine wave pattern PC and the basic sine wave pattern PS applied to the input terminals I2 and I3 and the correction patterns PHC and PHS applied to the input terminals I4 and I5, respectively, and the current shown in FIG. The pattern AI and the current pattern BI shown in FIG. 10D are output.

Further, the multipliers 53A and 53B multiply the current patterns AI and BI by the current command signal S2 and output the result as a current setting signal. Then, the current control circuit 55A
Indicates that the current flowing through the A-phase coil 26A is the current pattern AI.
So as to follow the current setting signal based on
A, 41A and 39A, 40A are turned on and off.

Here, in the positive half-wave period of the basic cosine wave pattern PC, the transistor 41A remains on and the transistor 38A repeatedly turns on and off by PWM control, and in the negative half-wave period of the current pattern AI. , The transistor 40A remains on, and the transistor 39A is repeatedly turned on and off by PWM control.

Similarly, the current control circuit 54B turns on and off the transistors 38B, 41B and 39B, 40B so that the current flowing through the B-phase coil 26B follows the current setting signal based on the current pattern BI. In this case, during the positive half-wave period of the current pattern BI, the transistor 41B remains on and the transistor 38B remains P.
The WM control repeatedly turns on and off, and during the negative half-wave period of the current pattern BI, the transistor 40B remains on and the transistor 39B repeatedly turns on and off by the PWM control.

When the exposure is completed, the selection signal S1 from the microcomputer 45 is switched to the brushless motor operation mode. Then, the position detection elements 34 and 35 have a position detection signal SA having a 180-degree conduction waveform with a phase shift of π / 2, as shown in FIGS. 11B and 11C.
And SB, and the drive signal forming circuit 51
11 from these position detection signals SA and SB.
As shown in (d), (e), (f), and (g), the drive signal A having a 90-degree conduction waveform whose phases are deviated from each other by π / 2.
+, B +, A- and B- are formed and output.

The stepping-brushless selection circuit 52, to which the selection signal S1 is applied, selects the brushless motor operation mode and is applied to the input terminals I6, I7, I8 and I9 of the drive signals A +, B +, A- and B-. Will be output. That is, the selection circuit 52 outputs the drive signal A +
And A- are output from the output terminal O1, and the drive signals B + and B- are output from the output terminal O2.

Further, the multipliers 53A and 53B multiply the drive signals A +, A- and B +, B- by the current command signal S2 and output it as a current setting signal. As a result, in the current control circuit 54A, the A-phase coil 26A causes the drive signals A + and A
The transistors 38A, 41A and 39A, 40A are turned on and off in the same manner as described above so as to follow the current setting signal based on −, and in the same manner, in the current control circuit 54B, the B-phase coil 26B drives the drive signal B +. And a transistor 38 so as to follow the current setting signal based on B-.
B, 41B and 39B, 40B are turned on and off.

Therefore, the scan motor 18 is reversely operated as a brushless motor in which the A-phase and B-phase coils 26A and 26B are always energized during the maximum period of the induced voltages VA and VB, and the maximum output is obtained. Is accelerated at high speed to move the carriages 5 and 8 back in the direction opposite to the arrow Q.

When the carriages 5 and 8 approach the home position shown by the solid line in FIG. 3 due to the reverse rotation of the scan motor 18,
The scan motor 18 is decelerated and then braked and stopped. At the time of this braking and stopping, for example, the transistors 40A, 41A and 40B, 41B are simultaneously turned on to short-circuit the A-phase and B-phase coils 26A and 26B to perform dynamic braking, or the transistors 38A to 41A and 38B. Through 41B, reverse rotation (normal rotation as the rotation of the scan motor 18) is performed by reversing the ON / OFF state, or the selection signal S1 is switched to the stepping motor operation mode to use the detent torque as the stepping motor. Braking is performed, and these braking modes are selected according to the load state.

According to this embodiment, the following effects can be obtained.

That is, as the scan motor 18, a stator 2 similar to a hybrid permanent magnet type stepping motor is used.
4 and the rotor 27, and the position detection elements 34 and 35 for detecting the rotational position of the rotor 27 are provided. Therefore, the scan motor 18 is a hybrid with little rotational vibration and rotational unevenness when the carriages 5 and 8 are moved forward. It can be operated as a permanent magnet type stepping motor, and can also be operated as a highly responsive brushless motor according to the position detection signals SA, SB based on the position detection elements 34, 35 when the carriages 5 and 8 are moved back.

Moreover, the scan motor 18 is moved under the control of the microcomputer 45 to the carriages 5 and 8.
The micro-step operation is performed as a stepping motor during the reciprocal movement of the stator coil 2 during the backward movement.
Since the A-phase and B-phase coils 26A and 26B in 6 are operated as a brushless motor in which the induced voltages VA and VB are always energized in the maximum range, the scan motor 18 rotates relatively smoothly during the forward movement. Thus, good copy image quality can be obtained, and the scan motor 18 can be accelerated with the maximum output at the time of the backward movement to improve the performance that the number of copies per unit time can be increased. obtain.

In particular, when the carriages 5 and 8 are moved forward, the basic cosine wave pattern PC and the basic sine wave pattern PS, which are the basic patterns from the basic pattern generation circuit 48, and the correction patterns PHC and PHS from the correction pattern generation circuit 49, respectively. A-phase coil 26A and B-phase coil 26B of the stator coil 26 based on the combined current pattern
Since the on-off control is performed, it is possible to cancel the detent torque generated by the magnetic imbalance between the rotor 27 and the stator 24. Therefore, it is possible to eliminate the uneven rotation of the rotor 27 due to the detent torque. High-accuracy constant speed operation can be enabled.

In the above embodiment, the scan motor 18
When the rotation is normal (the forward movement of the carriages 5 and 8), the correction patterns PHC and PHS are generated from the correction pattern generation circuit 49 when the rotation starts. For example, the correction patterns are generated until the rotation of the scan motor 18 is stabilized. The correction by PHC and PHS may not be performed.

In the above embodiment, when the scan motor 18 rotates in the normal direction, a sinusoidal current is passed through the scan motor 18 to drive the scan motor 18 at an extremely low speed, whereby the rising phase of the position detection signal is detected and stored. Therefore, it is also possible to adjust the shift of the phase of the correction pattern to reduce the accuracy required for the position detection signal.

Further, in the above embodiment, the position detecting means 34 is a Hall element, a position detecting element 34 including a Hall IC,
Although 35 is used, for example, a position detecting means including a combination of a slit disk and a photo interrupter may be used.

The above embodiment is a case where the present invention is applied to a scan motor of a dry copying machine, but the present invention is not limited to this, and a high precision constant speed operation such as a drive motor for driving a carriage of a printer is required. It can be applied to all drive motors.

[0064]

As described above, the control device for a drive motor according to the present invention is provided with a stator and a rotor having the same structure as that of a hybrid permanent magnet type stepping motor in the drive motor for microstep operation, and at the same time, the current is reduced. Since a correction pattern for canceling the detent torque generated by the magnetic imbalance between the rotor and the stator is combined with the basic pattern of, and the stator coil is switched on and off based on the combined current pattern, the drive motor is It has an excellent effect that it can be operated with high precision and constant speed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an electrical configuration showing an embodiment of the present invention.

FIG. 2 is a perspective view of a dry copying machine.

FIG. 3 is a sectional view of the main part.

FIG. 4 is a plan view of the original

FIG. 5 is a perspective view of a scan motor with a part cut away.

FIG. 6 is a perspective view of a rotor of a scan motor.

FIG. 7 is a waveform diagram for explaining the operation.

FIG. 8 is a waveform diagram for explaining the operation.

FIG. 9 is a waveform diagram for explaining the operation.

FIG. 10 is a waveform diagram for explaining the operation.

FIG. 11 is a waveform diagram for explaining the operation.

[Explanation of symbols]

In the drawing, 1 is a dry copying machine, 5 and 8 are first and second carriages, 18 is a scan motor (drive motor), 2
4 is a stator, 25 is a tooth portion, 25a is a small tooth magnetic pole,
26 is a stator coil, 26A is an A-phase coil, 26B is a B-phase coil, 27 is a rotor, 29 is a first rotor portion, 2
9a is a small tooth magnetic pole, 30 is a second rotor portion, 30a is a small tooth magnetic pole, 31 is a permanent magnet, 34 and 35 are position detecting elements (position detecting means), 36 is a drive circuit (driving means), 45
Is a microcomputer, 48 is a basic pattern generation circuit (basic pattern generation means), 49 is a correction pattern generation circuit (correction pattern generation means), 50 is a rotational position detection circuit (position detection means), and 52 is a stepping-brushless selection circuit ( The pattern synthesizing means) is shown.

Claims (1)

[Claims] 1. A stator in which a plurality of small tooth magnetic poles are formed on a tooth portion around which a plurality of phases of stator coils are wound, and a large number of small tooth magnetic poles are formed on the outer periphery, and the first magnet is magnetized to an N pole. 1 and a small tooth magnetic pole on the rotor
In a drive motor having a rotor having a second rotor portion magnetized to an S pole with a large number of small tooth magnetic poles displaced by a pitch of / 2 pitch, an induced voltage of the stator coil and a constant position. Position detection means for outputting a position detection signal having a phase difference, basic pattern generation means for generating a basic pattern of current, and detent generated by magnetic imbalance between the rotor and the stator based on the position detection signal of the position detection means. A correction pattern generating means for generating a current correction pattern for canceling the torque, a pattern synthesizing means for synthesizing the basic pattern and the correction pattern to generate a current pattern, and the above-mentioned based on the current pattern from the pattern synthesizing means. A control device for a drive motor, comprising: a drive means for controlling the on / off state of a stator coil.