JP2000184790A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce uneven rotation of a pulse motor. SOLUTION: The intervals of pulse signals P0, P1, P2, P3, P4,... formed to meet rotational speed with a preset target are corrected using a prescribed correction table to obtain pulse signals P10, P11, P12, P13, P14,.... That is, the pulse signal P11 is corrected so as to shorten the interval of the pulse signal based on a correction amount which the prescribed correction table indicates, and the pulse signal P12 is corrected so as to extend the interval of the pulse signal based on a correction amount which the prescribed correction table indicates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for driving and controlling a pulse motor, and more particularly to a motor control device characterized by a pulse signal generated corresponding to a target rotation speed.

[0002]

2. Description of the Related Art A stepping motor is an electric motor used for converting the number of pulses into a displacement, and is also called a pulse motor. Specifically, the rotor is configured to rotate by a predetermined angle in response to one of the given pulse signals, so that the rotation angle can be controlled based on the number of pulses. It is.

More specifically, when a stepping motor receives a pulse signal, it selects a stator to be excited, ie, an electromagnet, according to the phase of the rotor at that time, and supplies a predetermined amount of current to the excitation to excite it. Then, the magnetic poles of the rotor are attracted in the direction corresponding to the excited electromagnet and stopped. Also,
By continuously supplying the pulse signal to the stepping motor, the rotor can be rotatably driven and controlled. Since the above-described stepping motor is easily digitally controlled, it is employed in a carriage driving mechanism, a paper feeding mechanism, and the like in a printing apparatus such as a thermal transfer printer or a serial printer.

The current supply pattern for driving the stepping motor includes one-phase excitation, two-phase simultaneous excitation, 1-2-phase alternating excitation, W1-2-phase alternating excitation, and the like. Mainly 1-2 phase alternating excitation and W1-
Two-phase alternating excitation is employed.

[0005] The driving method of the stepping motor by the 1-2-phase alternating excitation is that each electromagnet corresponding to the phase of the rotor, that is, one-phase excitation that sequentially excites each phase one by one and rotates at the basic step angle, In this method, two adjacent phases are simultaneously excited, and two-phase simultaneous excitation in which the excitation of one of the phases is switched in the phase switching is alternately repeated. According to this driving method, the rotor can be stopped at one of a stop position by one-phase excitation or a stop position by two-phase simultaneous excitation rotated by の of the basic step angle according to the supplied current. It is possible. For example, in order to rotate the rotor once, according to one-phase excitation, 4
When steps are required, eight steps are required, which is twice that of the 1-2 phase alternating excitation. Its features are 1-phase excitation or 2
It is possible to finely control the step width as compared with the simultaneous phase excitation, and it is also excellent in reducing noise during driving and stabilizing high-speed driving.

A method of driving a stepping motor by W1-2-phase alternating excitation is a method of driving and controlling a half width of the basic step angle of the 1-2-phase alternating excitation as described above. Can be supplied to a value in one-phase excitation and two lower intermediate values, and the phase is switched by stepwise increasing or decreasing excitation of one phase using the intermediate value. ing. According to this driving method, the rotor is stopped at either a stop position by 1-2 phase alternating excitation or a stop position rotated by １ ／ of the basic step angle in accordance with the supplied current. For example, in order to rotate the rotor once, 1-2
According to the phase shift excitation, when eight steps are required, W1-2
According to the phase shift excitation, 16 steps are required, twice as much. The feature is that it is possible to control the step width finer than the above-mentioned 1-2 phase alternating excitation, and is used when high accuracy is required.

FIG. 5 is a timing chart for explaining an example of the current supply timing of the 1-2-phase alternating excitation and the W1-2-phase alternating excitation. FIG. 5 (1-A) and FIG. 5 (1-B)
Represents the current supply timing of the A phase (corresponding to the horizontal direction) and the B phase (corresponding to the vertical direction) in the 1-2 phase alternating excitation, respectively. In this 1-2-phase alternating excitation, five stages of current amounts can be set for each of the A phase and the B phase. For eight phases obtained by dividing one round by a basic step angle, for example, the rotor magnetic pole is set to 0. In order to drive to the phase 0 corresponding to the time direction, no current is supplied to the phase A that gives a horizontal moment, and only the current B is supplied to the phase B that gives a vertical moment. To drive to phase 1 corresponding to the direction of 1:30, equivalent currents are supplied to the A phase and the B phase.

On the other hand, FIGS. 5 (2-A) and 5 (2-B) show W1
4 shows the current supply timings of the A-phase and the B-phase in the -2 phase alternating excitation, respectively. In the W1-2-phase alternating excitation, seven phases of current amounts can be set for each of the A phase and the B phase. For 16 phases obtained by dividing one round by the basic step angle, for example, the rotor magnetic pole is set to 0. To drive to phase 0 corresponding to the time direction, no current is supplied to phase A and B
Supply -100% current to the phase. To drive to phase 1 corresponding to the direction of 0:45, a current of about 40% is supplied to phase A, and a current of -100% is supplied to phase B as in phase 0. Furthermore, in order to drive to the phase 2 corresponding to the direction of 1:30, approximately 70% of the current is supplied to the A phase and the B phase.

FIG. 6 is a speed diagram for explaining the speed control of the stepping motor, in which the horizontal axis represents time, and the vertical axis represents the target value of the rotation speed of the stepping motor. In the figure, the rotation speed is accelerated from time T0 to time T1 when the speed line shows an upward tendency.
Represents the period. The rotation speed of the stepping motor is proportional to the number of pulse signals per unit time. For example, when driving at a rotational speed of 400 pps when there is one pulse signal given per unit time, by increasing the pulse signals given per unit time from the start of driving to 1, 2, 3, ... Reaches 400 pps in the first unit time, reaches 800 pps in the next unit time, and reaches 1200 pps in the next unit time. In other words, the rotation speed is inversely proportional to the pulse signal interval. Therefore, the rotation speed is accelerated by gradually shortening the interval between the pulse signals applied to the stepping motor.

The period from time T1 to time T2, at which the speed line shows a tendency to level, represents the second period in which the driving is performed while the rotation speed is kept constant. During this period, the interval between pulse signals given to the stepping motor is kept constant. Dripping. In addition, the period from time T2 to time T3 at which the speed line shows a downward trend represents the third period in which the rotation speed is reduced. During this period, the interval of the pulse signal to be applied to the stepping motor is gradually increased with time. Is controlled to be longer.

A recording apparatus proposed in Japanese Patent Application Laid-Open No. 4-131265 is an invention characterized by speed control during acceleration of a stepping motor, wherein the driving force of the stepping motor is controlled by using a gear train or the like. By transmitting a predetermined number of pulses at a low speed from the start of driving, the backlash period until the driving force is transmitted to the transport roller when the transport direction is reversed by a mechanism that transmits to the transport roller via the transmission mechanism. An object of the present invention is to prevent the stepping motor from accelerating and causing a sudden change in torque when the driving force is transmitted to the transport roll to prevent the stepping motor from stepping out.

By the way, in the stepping motor used in the printing apparatus, there is a slight difference in the braking torque between the phases due to the movement characteristics of the load driven by the stepping motor. For example, the braking torque when driving the stepping motor from phase 0 to phase 1 does not match the braking torque when driving the stepping motor from phase 1 to phase 2. In such a situation,
For example, if pulse signals are given at equal intervals in order to drive while keeping the rotation speed constant, rotation unevenness occurs between specific phases. The rotation unevenness appears as waving of a speed diagram representing the measured value of the rotation speed of the stepping motor and ringing of the rising edge thereof, which causes problems such as deterioration of print quality and generation of noise.

Conventionally, the above-described rotation unevenness has been reduced by improving the overall accuracy of the driving mechanism or by employing a stepping motor having excellent driving stability. In addition, when the rotation speed is low, the rotation unevenness is reduced. Therefore, in the specification design of the printing apparatus, it is also necessary to limit the speed of the stepping motor so that the rotation unevenness during operation does not cause a problem. Had been

[0014]

However, there is a strong demand for a printing apparatus to increase the printing speed, and responding to this is an important issue. However, increasing the rotation speed of the stepping motor causes an increase in rotation unevenness. Therefore, there has been a problem that problems such as deterioration of print quality and generation of noise caused by the increase must be solved.

The present invention has been made in view of the above circumstances, and controls the interval between pulse signals generated corresponding to a target rotation speed in accordance with a braking torque for each phase of a stepping motor. It is an object of the present invention to provide a motor control device that reduces rotation unevenness by doing as much as possible.

[0016]

SUMMARY OF THE INVENTION A motor control device according to the present invention has a speed control table indicating switching timing of a rotation speed, and generates a pulse signal corresponding to a rotation speed set based on the speed control table. In a motor control device that generates and supplies this to a motor to control the drive of a rotor of the motor at each basic step angle, the motor control device sets the drive start position for each phase that is a stop position at each basic step angle of the motor. The correction table storing the correction amount of the pulse signal interval and the phase of the driving start position are identified in association with the phases in which the driving order is continuous, and the phase is obtained by referring to the correction table accordingly. Means for correcting the interval between the generated pulse signals according to the correction amount, and means for supplying the pulse signal with the corrected interval to the motor. It is characterized in.

FIG. 3 is a conceptual diagram for explaining the concept of the correction table according to the present invention. FIG. 3A shows a correction table when the phase at the start of driving is 0, in which the horizontal axis corresponds to the phase, and the vertical axis corresponds to the correction amount of the pulse signal interval. Is shown. FIGS. 3 (b), 3 (c) and 3 (d) show correction tables in the case where the phases at the start of driving are 1, 2 and 3, respectively.
This is illustrated similarly to FIG.

For example, when the phase at the start of driving is 0, the correction table shown in FIG.
The correction is performed based on the correction amount indicated by the point so as to shorten the interval from the first pulse signal, that is, the pulse signal driven from phase 0 to phase 1 to the next pulse signal. Further, based on the correction amount indicated by the point B in the figure, the correction is performed so as to extend the interval from the pulse signal to the next pulse signal. On the other hand, if the phase at the start of driving is 1, 2 or 3, the pulse signal is appropriately adjusted using the correction tables shown in FIGS. 3 (b), 3 (c) and 3 (d), respectively. Correct the interval of. The correction table as described above is set in advance based on experimental values. A similar correction table is set for the reverse rotation direction.

FIG. 4 is a conceptual diagram for explaining a pulse signal whose pulse signal interval has been corrected using the correction table. FIG. 4A shows pulse signals P0, P1, P2, P3, P4,... Generated corresponding to the target rotation speed, and FIG. .. Represent pulse signals P10, P11, P12, P13, P14,... Obtained by correcting the intervals of the represented pulse signals by using the correction table of FIG. That is, the pulse signal P11 in FIG. 4B is corrected based on the correction amount indicated by the point A so as to shorten the interval between the pulse signals. The pulse signal P12 is corrected based on the correction amount indicated by the point B so as to extend the interval between the pulse signals.

As described above, in the present invention, the above-described correction table is set in advance based on experimental values, and the interval between pulse signals is controlled using the correction table to reduce rotation unevenness. be able to.

[0021]

FIG. 1 is a block diagram showing the configuration of a motor control device according to the present invention. In the figure, ROM
Ramp table 2 stored in 1 is a speed control table indicating the switching timing of the rotation speed.
The data can be read by the Ramp data correction circuit 3. The Ramp data correction circuit 3 is provided with a plurality of correction tables 4 for storing the correction amount of the pulse signal interval corresponding to the difference of the braking torque between the successive phases according to the phase at the start of driving. It is. The Ramp data correction circuit 3 is adapted to receive the setting of the drive direction, and when a predetermined trigger signal is received, the ROM 1
Table 2 and phase register 5 stored in
Is read out, and pulse data representing a pulse signal interval is generated based on the set driving direction, and the pulse data is supplied to the pulse generation circuit 6.

The pulse generating circuit 6 is adapted to receive a high-frequency clock, and provides a pulse signal to the motor driver 7 in accordance with given pulse data. When receiving the pulse signal, the motor driver 7 performs a predetermined driving method,
That is, a predetermined current based on the current supply pattern is supplied to the motor 8.
Supply to Each time the pulse generation circuit 6 outputs a pulse signal, it supplies a trigger signal to the phase identification circuit 9. The phase identification circuit 9 is adapted to receive the setting of the driving direction, and upon receiving a trigger signal, identifies a phase transition based on the set driving direction,
This is stored in the phase register 5.

FIG. 2 is a flowchart showing the operation procedure of the motor control device according to the present invention. When receiving the trigger signal, the Ramp data correction circuit 3 reads the phase information stored in the phase register 5 (S1). The Ramp table 2 is selected based on the read phase information and the set driving direction (S2), and Ramp data is read (S3). Then, the read Ramp data is corrected based on the correction table 4 to generate pulse data (S4), and this is supplied to the pulse generation circuit 6. The pulse generation circuit 6 generates a pulse signal according to the pulse data (S5), and supplies the pulse signal to the motor driver 7 to drive the motor 8 (S6). The Ramp data is read from the selected Ramp table 2 (S7), and it is determined whether or not the data is end (S8). If not, the process returns to S4 and the subsequent steps are repeated. If it is determined that the data end has occurred, the process ends.

[0024]

According to the motor control device of the present invention as described above, a correction table for defining the correction amount of the interval between pulse signals in accordance with the braking torque for each phase of the motor is set in advance, and according to this correction table. Since the interval between pulse signals is controlled, an excellent effect of reducing rotation unevenness can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a motor control device according to the present invention.

FIG. 2 is a flowchart showing an operation procedure of the motor control device according to the present invention.

FIG. 3 is a conceptual diagram for explaining the concept of a correction table according to the present invention.

FIG. 4 is a conceptual diagram for explaining a pulse signal whose pulse signal interval has been corrected using the correction table according to the present invention.

FIG. 5 is a timing chart for explaining an example of current supply timings of the 1-2 phase alternating excitation and the W1-2 phase alternating excitation.

FIG. 6 is a speed diagram illustrating speed control of a stepping motor.

[Explanation of symbols]

 2 Ramp table 3 Ramp data correction circuit 4 Correction table 5 Phase register 6 Pulse generation circuit 9 Phase identification circuit

Claims (1)

[Claims] A speed control table that indicates a switching timing of a rotation speed, and generates a pulse signal corresponding to a target rotation speed based on the speed control table;
A motor control device that controls the driving of the rotor of the motor for each basic step angle by providing the motor with the motor. A correction table for storing the correction amounts of the pulse signal intervals in association with the successive phases, and a correction amount obtained by referring to the correction table by identifying the phase of the drive start position and correspondingly identifying the phase. A motor control device comprising: means for correcting an interval between generated pulse signals; and means for supplying a pulse signal whose interval has been corrected to the motor.