JPH10174493A - Stepping motor control circuit - Google Patents

Abstract

(57) [Summary] [Object] To provide a stepping motor control circuit that achieves high efficiency, high-speed start-up, high-speed fall, and high-speed rotation and can eliminate step-out which is a drawback of the stepping motor. [Structure] As a configuration of a control circuit of a stepping motor, a position detection device that rotates in conjunction with a rotation axis of the stepping motor and generates a pulse signal corresponding to a rotation position of the rotor, and determines a direction based on an output of the position detection device And a rotor position detection circuit that performs pulse counting based on the output of the direction determination circuit and detects the rotor position of the stepping motor, and energizes an arbitrary coil of the stepping motor, and sets the time when the rotor is stabilized. A reference position detection device that determines a reference value using the value of the rotor position detection circuit, and a coil of the stepping motor is energized by an output of the rotor position detection circuit according to the position from the reference determined by the reference position detection device. And a drive for driving the stepping motor by the output of the conduction control circuit. And a dynamic circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit for a stepping motor used in a sub-scanning system of a large-size raster scan type printer.

[0002]

2. Description of the Related Art Conventionally, a stepping motor has been generally used in a sub-scanning system of a raster scan type printer. The reason for this is that position control can be performed in an open loop, which is the greatest feature of a stepping motor.

[0003] In recent years, ink jet printers have replaced dot printers as quiet printers, which are optimal as office and home printers. In recent years, the power of a computer CPU has been increased, and applications for handling images have been increased, and printers with higher image quality and higher resolution have been demanded.

Next, the operation of the stepping motor of the sub-scanning system of the ink jet printer will be described. The case where the load is moved to the target position by the motor in the shortest time will be specifically considered. For example, a description will be given with reference to FIG. The relationship between the target position and the speed (running characteristic curve) shown in FIG. 14 also applies to an embodiment of the present invention described later. As shown in FIG. 14, the platen of the sub-scanning
Then, it rotates at the maximum speed. Therefore, when it is desired to drive the platen in the shortest time, it is desirable to shorten the rise time in the section A. After the platen is driven in a predetermined direction, it is desirable to rapidly reduce the speed of the platen in section C, and then to drive the platen at low speed as shown in section D in order to perform highly accurate positioning. It is well known that a running characteristic curve as shown in the figure can be arbitrarily set.

[0005]

Since there is no rotor position control for energizing the coil of the stepping motor, energization is not performed at an energizing angle suitable for the coil, the motor easily loses synchronism, and the rotation speed generally increases. Can not hope. In addition, it rotates in synchronization with the step frequency in a form where positive torque and counter torque coexist,
In addition, at low speeds, the rotation and the stop are alternately repeated, so that noise is easily generated. Therefore, it is not suitable for the current non-impact printer mainstream office environment.

That is, the rising time and the falling time are shortened as in the section A and the section C shown in FIG.
Alternatively, when driving at a high speed as in the section B, it is difficult to follow up when a stepping motor is used, and when the motor is rotated at a high speed, there is a drawback that a step-out phenomenon easily occurs. Therefore, when performing position control in the shortest time, the stepping motor is not suitable.

Further, it is necessary that the feed accuracy of the sub-scanning system of a high-gradation, high-resolution ink jet printer is very high as compared with the prior art, and the step angle of the stepping motor is limited by the number of teeth and the number of phases of the coil. Increasing the step angle, as determined by the mechanical factors, results in increased costs. Further, if the reduction ratio is increased while keeping the conventional step angle, the arrival time to the target position is increased.

Accordingly, an object of the present invention is to realize a stepping motor control which realizes high efficiency, high speed start-up, high speed fall, and high-speed rotation, which are characteristics of a DC motor, and eliminates step-out which is a drawback of the stepping motor. It is to provide a circuit.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a control circuit for a stepping motor, which rotates in conjunction with a rotation axis of the stepping motor and is adapted to a rotation position of the rotor. A position detecting device that generates a pulse signal, a direction determining circuit that determines a direction based on an output of the position detecting device, and a rotor position detecting circuit that performs pulse counting based on an output of the direction determining circuit and detects a rotor position of a stepping motor And a reference position detecting device that supplies a current to an arbitrary coil of the stepping motor and determines a reference value by using a value of the rotor position detecting circuit at the time when the rotor is stabilized. Energization control that energizes the coil of the stepping motor by the output of the rotor position detection circuit according to the position from the reference It is to employ a circuit, a drive circuit for driving the stepping motor by the output of vent electric control circuit, a control circuit of a stepping motor and having a.

[0010]

【Example】

(Embodiment 1) FIGS. 1 to 3 are diagrams for explaining the principle of a four-phase unipolar stepping motor. FIG. 1 shows a relationship between a stator and a rotor of a stepping motor. In FIG. 1, reference numeral 1 denotes a stator made of a magnetic material. Symbols 1A, 1B, 1C, and 1D are salient pole portions of the magnetic body 1, and coils 2A, 2B, 2C, and 2D are mounted on each salient pole portion. Common terminal (C) for each coil terminal
And drive terminals (φ1, φ2, φ3, φ4). Reference numeral 3 denotes a rotor made of a two-pole magnet, which rotates around a rotation shaft 4. In the relationship between the rotor and the stator, in the case of FIG. 1, the mechanical angle and the electrical angle are the same. The coil 2A and the coil 2C are shifted by 180 degrees in electrical angle, the coils 2B and 2D are also shifted by 180 degrees in electrical angle, and the coils 2A and 2C are shifted by 90 degrees in electrical angle. . Therefore, it is generally said that there is a two-phase relationship.

The common terminals (C) of the coils 2A and 2C are connected to each other, and the common terminals (C) of the coils 2B and 2D are connected to each other.
When two coils are regarded as one and the terminals φ2 and φ4 are regarded as a B-phase coil, and reciprocating current is applied to each of the A-phase and B-phase coils, it is called two-phase bipolar drive. In the present invention, only a four-phase unipolar will be described, but a similar effect can be obtained in a two-phase bipolar stepping motor.

FIG. 2 is a diagram for explaining a drive circuit for driving the coil. In FIG. 2, symbol 5 is a DC power supply. 2 that are the same as those shown in FIG. 1 indicate members having the same functions and the same functions and effects, and a description thereof will not be repeated. FIG. 3 shows the timing at which the coil shown in FIG. 2 is energized.
3, a signal for opening and closing S4, which conducts to the coil at a high level.

FIG. 4 is a block diagram for explaining the present embodiment. In FIG. 4, reference numeral 11 denotes a four-phase stepping motor. Symbol 12 is a position detecting device, for example, a two-phase encoder device. The two-phase encoder device is connected to the rotation shaft of the stepping motor 11, and rotates with the rotation of the rotation shaft. Symbol 13
Performs the direction determination of the output of the encoder 12 by the direction determination circuit. Symbol 14 is for detecting the rotor position by counting the output determined in the direction by the rotor position detection circuit. Reference numeral 15 denotes a control unit which includes a reference position detecting device, a power supply control circuit, and the like, performs various controls, and drives a stepping motor via a drive circuit of reference numeral 16.

FIG. 5 is a diagram for explaining the direction discriminating circuit 13 of FIG. In FIG. 5, the case of clockwise rotation (CW) of the stepping motor will be described.
W) has the same operation. FIG. 5A shows the A-phase and the B-phase of the two-phase encoder. FIG. 5B is a diagram in which the rising and falling of the A-phase and the B-phase of the two-phase encoder are pulsed, including the direction discrimination.

FIG. 6 is a diagram for explaining the rotor position detection circuit 14 and the control unit 15 of FIG. FIG. 6 (a)
Is a signal obtained by pulsing the rising and falling edges of the A and B phases of the two-phase encoder, including the direction determination, into a position signal. The pulse is input to the rotor position detection circuit 14 and counted to detect the rotor position.

FIG. 6B is a diagram in which a signal for energizing a two-phase bipolar coil is created using the signal of FIG. 6A. FIG. 6C shows a signal converted for a four-phase unipolar motor using the signal of FIG. 6B. By the control unit 15 of FIG. 4, each of φ1,
The currents corresponding to the signals 2, 3, and 4 are represented by φ of each coil in FIG.
By energizing 1, 2, 3, and 4, only positive torque can be generated. However, regarding the position relation, when the position in FIG. 1 is started, it is necessary to set the symbol 21 in FIG.

Next, the means for determining the start time of the rotor by the control unit 15 will be described with reference to FIGS. FIG. 7 shows a main routine, in which the rotor position is initialized in step 32, motor control is performed in step 33, various other controls are performed in step 34, and the process returns to step 33.

FIGS. 8 to 10 show a routine for initializing the rotor position. FIG. 8 illustrates the first method. In step 42, for example, only the coil φ1 is energized, and after a predetermined time, in step 43, the point at which the rotor stably stops is determined as the start point.

FIG. 9 illustrates the second method, which takes into account the correction of the position shift due to the friction load when the rotor position is initialized, and includes the correction of the position shift.
In step 52, the coil φ4 is energized, and after a predetermined time, in step 53, the coil φ1 is energized. After a predetermined time, in step 54, at the position where the rotor stably stops, φ1R =
Set to 0. Next, in step 55, the coil φ2 is energized, and after a predetermined time, in step 56, the coil φ1 is energized. After a predetermined time, at step 57, φ1L = rotor position at the position where the rotor stably stops. At step 58,
By taking the average of φ1R and φ1L and changing the value of the rotor position, the position where the stator 1A and the N pole of the rotor face each other can be made zero.

FIG. 10 illustrates the third method.
This takes into account correction when the positions of the salient poles 1A, 1B, 1C, and 1D shown in FIG. First, in step 72, the coil φ4 is energized,
Wait for a predetermined time to elapse. In step 73, the coil φ1 is energized. After a predetermined time, in step 74, φ1R = 0 is set at the position where the rotor stably stops. Then step 75
To energize the coil φ2. After a predetermined time, step 76
At the position where the rotor has stably stopped, φ2R = rotor position. Next, the same operation is performed on the coils φ3 and φ4 in steps 77 to 80, and φ3R, φ3
Find the value of 4R. Next, the same operation is performed for the rotation in the opposite direction.
3, φ2, φ1, φ4, φ3L, φ2L,
Find the values of φ1L and φ4L. The calculations are performed for steps 89 to 92 to detect the positions of the stable points during normal rotation and reverse rotation for each coil,
The average of the forward rotation and the reverse rotation of each coil is averaged to reduce the influence of the friction load. Next, in step 93, φ
The value of 4 is used as the position of the rotor. Next, in steps 94 to 97, the position of the rotor opposed to each coil is obtained by calculation, and distribution is performed at equal intervals between adjacent salient poles. Be prepared to respond.

In FIG. 6C, the energization is performed by a pseudo triangular wave, but the object of the present invention can be achieved by using a rectangular wave.

(Embodiment 2) Next, means for stopping a rotor of a stepping motor at a target position by using a two-phase encoder will be described.

The micro step drive of the stepping motor is used. Next, the micro-step driving will be described. For example, a description will be given of a four-phase unipolar motor with reference to FIG. When power is supplied only to the coil 2A, the N pole of the rotor 3 faces the salient pole 1A. When current is applied only to the coil 2B, the N pole of the rotor 3 faces the salient pole 1B. When the same amount of current is applied to the coils 2A and 2B, the rotor 3 stops at an intermediate position between the salient poles 1A and 1B. That is, by arbitrarily changing the amount of current distribution to each coil, it is possible to stop at any position.

Next, the means for controlling the position by the signal of the encoder will be described. FIG. 11 is a routine of the motor control 33 of FIG. In step 102, position control is performed, and in step 103, stop position control is performed. In the position control of step 102, the output signal of the encoder is measured including the direction determination, and feedback control is performed so as to converge on the target position.

FIG. 12 is a flowchart for explaining the stop position control. In step 112, the difference between the target position and the current position is regarded as an error.
For example, it corresponds to one-phase energization of a four-phase stepping motor.
If it has reached two steps or less and has reached the position where the one-phase energization has been stabilized, the routine proceeds to step 115. Step 1
At 15, move to the micro step drive, and go to step 11
At 6, it is determined whether or not the target position is reached, and micro-step driving is performed until the target position is reached.

(Embodiment 3) Next, means for stopping the rotor of the stepping motor at a target position using an analog signal of a two-phase encoder will be described. FIG.
Is a timing chart for explaining the embodiment. FIG. 13A shows output waveforms of an analog output two-phase encoder obtained using an MR element or the like. FIG.
(B) is a waveform-shaped version of the encoder output of FIG. 13 (a). FIG. 13 (c) is obtained by pulsing the rise and fall of the waveform of FIG. 13 (b), and is used for rotor position detection and current position detection for reaching the target position. In the second embodiment, the pulse motor could reach the pulse accuracy of the encoder. In the present embodiment, the position accuracy within one pulse is made possible by using the analog voltage of the encoder. FIG. 13D shows an A-phase analog signal of the encoder extracted using a B-phase signal. If the analog signal of the encoder deviates from the target point of symbol 121, position feedback control is performed so as to return to the target point by micro-step driving.

(Embodiment 4) FIG. 14 is a diagram showing the relationship between the target position and the speed. The horizontal axis represents the position, and the vertical axis represents the speed of the stepping motor. When a new target value is set for the stepping motor, the stepping motor starts the rising section A set in the rising curve setting.
The motor accelerates between the two and reaches the maximum speed.
Travel at the maximum speed in the section B up to. When the set value 1 is reached, the vehicle decelerates during the falling section C set in the falling curve setting, and when the speed reaches the minimum speed, it moves to the target position at the minimum speed. Then, when it reaches the target position, it stops. The stop control method can be performed using the second and third embodiments.

There are two types of means for constant speed control. One of them is a constant speed control based on the open control originally provided in the stepping motor, and the stop is performed using the stop control method of the second and third embodiments by utilizing this controllability as it is.

Next, the second means will be described. FIG. 15 is a block diagram for controlling the stepping motor.
Reference numeral 201 denotes a stepping motor, and reference numeral 202 denotes a two-phase encoder device connected to a rotation shaft of the stepping motor. Symbol 204 determines the direction based on the output of encoder 202. Reference numeral 205 denotes a rotor position detection circuit, which detects the position by counting the output whose direction has been determined. Reference numeral 206 denotes a current position detection circuit, which detects a position by counting outputs whose directions have been determined. Reference numeral 207 denotes a speed detector which detects the speed based on the output of the direction determination 204. Symbol 20
8 is a target position. A control unit 209 includes a rotor position detection circuit 205, a target value 208, and a current position circuit 206.
And the output of the speed detector 207 are input, various processes are performed, and the stepping motor 201 is driven via the drive circuit of the symbol 210.

Next, the method of constant speed control will be described. The speed is detected by the speed detector 207, and the power applied to the four-phase stepping motor is controlled so as to converge on the set speed. For example, the control method is performed by controlling the amplitude value shown in FIG. The object of the present invention can be achieved even if control is performed by other known means.

FIG. 16 is a flowchart for explaining the control operation of the control unit in FIG. Reference numeral 221 denotes a main routine. In step 222, it is determined whether the target value has been changed. If the target value has been changed, the target value change initialization is performed. In step 223, the target value is set to a new target value. Next, in step 224, the speed set value is set to zero. At step 225, the target value change initialization ends. Next, a determination process is performed in step 226. Next, the process proceeds to step 227 and ends. If it is determined in step 222 that the target value change initialization has already been performed, the process proceeds to step 227 and ends.

FIG. 17 is a detailed flowchart of the determination processing in step 226 of the flowchart of FIG. In step 232, the difference (error) between the target position and the current position is determined. At step 233, a positive / negative determination is made. When the error is positive, right rotation is performed at step 234, and when the error is negative, left rotation is performed at step 235. Step 2
When the absolute value of the error is larger than the set value 1 (first set value) by 36 and the speed set value is smaller than the maximum speed by step 237, the speed set value is set to 11 (first speed set value) by step 238. The number is increased and the determination process ends. If the speed setting value is equal to or higher than the maximum speed in step 237, the determination process ends. Step 236
When the error is equal to or smaller than the set value 1, the process proceeds to step 239. When the speed set value exceeds the minimum speed, the process proceeds to step 239.
By 40, the speed set value is decreased by the set value 12 (second speed set value). When the speed set value is equal to or lower than the minimum speed in step 239, the process proceeds to the end of step 241.
The determination processing routine ends.

[0033]

As described above, according to the present invention,
By using a stepping motor equipped with a two-phase encoder in the sub-scanning system of the printer, high efficiency, high-speed startup, high-speed shutdown, and high-speed rotation, which are the characteristics of the DC motor, are realized. It became possible to eliminate the tone. Then, the noise can be reduced, and the vehicle can reach the target position at high speed.

Further, by using a two-phase encoder capable of analog output for the stepping motor, it is possible to stop at the center voltage of the encoder, and the encoder can be positioned with high accuracy within one step of the encoder. As a result, it is possible to significantly reduce unevenness in the feeding of the printer.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the principle of a four-phase unipolar stepping motor.

FIG. 2 is a diagram for explaining the principle of a four-phase unipolar stepping motor.

FIG. 3 is a diagram for explaining the principle of a four-phase unipolar stepping motor.

FIG. 4 is a block diagram for explaining the embodiment.

FIG. 5 is a diagram for explaining a direction discriminating circuit 13 of FIG. 4;

FIG. 6 is a diagram for explaining a rotor position detection circuit and a control unit in FIG. 4;

FIG. 7 is a main routine.

FIG. 8 is a routine of rotor position initialization.

FIG. 9 is a routine of rotor position initialization.

FIG. 10 is a routine of rotor position initialization.

FIG. 11 is a motor control routine of FIG. 7;

FIG. 12 is a motor control routine of FIG. 7;

FIG. 13 is a diagram for explaining a third embodiment;

FIG. 14 is a diagram for explaining the third embodiment, and is a diagram illustrating a relationship between a target position and a speed.

FIG. 15 is a block diagram for controlling a stepping motor.

FIG. 16 is a flowchart illustrating a control unit of FIG. 15;

FIG. 17 is a detailed flowchart of a determination process in step 226 of the flowchart in FIG. 16;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator made of magnetic material 1A, 1B, 1C, 1D Salient pole part 2A, 2B, 2C, 2D coil 3 of magnetic material 1 Rotor 4 made of two-pole magnet 4 Rotary shaft 11, 201 Stepping motor 12, 202 Two-phase encoder 13, 204 Direction determination circuit 14, 205 Rotor position detection circuit 15 Controller 16, 210 Drive circuit 206 Current position 207 Speed detector 208 Target position 209 Control circuit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02P 8/38 H02P 8/00 R 303B

Claims (8)

[Claims] In a control circuit of a stepping motor, the stepping motor rotates in conjunction with a rotation axis of the stepping motor,
A position detecting device that generates a pulse signal corresponding to the rotational position of the rotor; a direction determining circuit that determines a direction based on an output of the position detecting device; a pulse count is performed based on an output of the direction determining circuit; And a rotor position detection circuit for detecting, energizing an arbitrary coil of the stepping motor,
A reference position detecting device that determines a reference value using the value of the rotor position detecting circuit at the time when the rotor is stabilized, and an output of the rotor position detecting circuit according to the position from the reference determined by the reference position detecting device. A control circuit for a stepping motor, comprising: an energization control circuit that energizes a coil of the stepping motor; and a drive circuit that drives the stepping motor by an output of the energization control circuit. 2. A control circuit for a stepping motor, comprising: rotating in conjunction with a rotation axis of the stepping motor;
A position detecting device that generates a pulse signal corresponding to the rotational position of the rotor; a direction determining circuit that determines a direction based on an output of the position detecting device; a pulse count is performed based on an output of the direction determining circuit; And a rotor position detection circuit for detecting, energizing an arbitrary coil of the stepping motor,
A reference position detecting device that determines a reference value using the value of the rotor position detecting circuit at the time when the rotor is stabilized, and an output of the rotor position detecting circuit according to the position from the reference determined by the reference position detecting device. An energization control circuit that energizes the coil of the stepping motor; a microstep drive circuit that can stop the rotor at an arbitrary position by arbitrarily setting an energizing current ratio of each coil of the stepping motor; and the rotor position detection circuit. A first stop position control circuit that controls the current ratio of the coil of the micro step control circuit so that the position signal of the rotor position detection circuit becomes a set value by the position signal, And a drive circuit for driving the stepping motor by the output of the micro-step drive circuit. The control circuit of a stepping motor according to. 3. A control circuit for a stepping motor, comprising: rotating in conjunction with a rotation axis of the stepping motor;
A position detection device that generates a pulse signal having an analog region corresponding to the rotational position of the rotor, a waveform shaping circuit that shapes the waveform of the output of the position detection device, and a direction determination that determines a direction based on the output of the waveform shaping circuit A circuit, a pulse count is performed based on an output of the direction determination circuit, a rotor position detection circuit that detects a rotor position of the stepping motor, and an arbitrary coil of the stepping motor is energized,
A reference position detecting device that determines a reference value using the value of the rotor position detecting circuit at the time when the rotor is stabilized, and an output of the rotor position detecting circuit according to the position from the reference determined by the reference position detecting device. An energization control circuit that energizes the coil of the stepping motor; a microstep drive circuit that can stop the rotor at an arbitrary position by arbitrarily setting an energizing current ratio of each coil of the stepping motor; and the rotor position detection circuit. The first stop position control circuit that controls the current ratio of the coil of the micro-step control circuit so that the position signal of the rotor position detection circuit becomes a set value, Control the current ratio of the coil of the micro-step control circuit so that the analog signal is fixed at a predetermined value. A second stop position control circuit, and a drive circuit for driving the stepping motor by the outputs of the energization control circuit and the micro-step drive circuit. 4. The stepping motor control circuit according to claim 1, wherein a speed detection circuit detects a speed based on an output of the direction determination circuit, and a pulse count is performed based on an output of the direction determination circuit. Do
A current position circuit that measures a current position, a speed detection circuit that detects speed based on an output of the direction determination circuit, a determination circuit that performs various determinations based on the output of the speed detection circuit and the current position circuit, and a target position, A control circuit for controlling the stepping motor in the sub-scanning system of the printer, wherein the stepping motor is driven by an output of the determination circuit. 5. The stepping motor control circuit according to claim 1, wherein the position detection device uses a two-phase encoder device. 6. The control circuit for a stepping motor according to claim 1, wherein the reference position detection device supplies a current to a coil corresponding to any one of the salient poles and determines a position where the rotor stops. A control circuit for a stepping motor, wherein the control circuit is set to a reference position. 7. The stepping motor control circuit according to claim 1, wherein the reference position detection device calculates an average position of stop positions of right rotation and left rotation with respect to any one of the salient poles. A control circuit for a stepping motor, wherein the control circuit is set to a reference position. 8. The stepping motor control circuit according to claim 1, wherein the reference position detection device calculates an average position of right and left rotation stop positions with respect to each salient pole. A control circuit for a stepping motor, wherein a reference position is determined by equally distributing spaces between salient poles.