JPH0538198A - Method of controlling for pulse motor - Google Patents

Abstract

PURPOSE:To enhance reliability and throughput by preventing step-out due to fluctuation of motor performance or load and the timing of motor start, and lowering of throughput due to prolongation of initial lock time or slow acceleration/deceleration. CONSTITUTION:In the control method for polyphase excitation pulse motor wherein rotational angle control of rotor is performed by rotating a combined field vector formed by a plurality of exciting coils, rotor position with respect to the combined field vector at previous stop time is decided at the start of rotation of the rotor (step S14, S15) and then locking process of rotor takes place (step S16-S18) by setting a lock time corresponding to thus decided position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse motor control method, and more particularly to a method for controlling a multi-phase excitation type pulse motor which controls a rotation angle of a rotor by rotating a composite magnetic field vector formed by a plurality of excitation coils. It is about.

[0002]

2. Description of the Related Art Printers, facsimile machines, copying machines,
A pulse motor is widely used as a drive source for various other office equipment and the like. Since this pulse motor can rotate the rotor by a certain rotation angle by a single pulse, it is a motor suitable for transporting an object with high accuracy because of its good controllability.

An outline of, for example, a printer using a pulse motor will be described below. The printing paper is wound around the platen of the printer, and a so-called line feed motor (hereinafter abbreviated as LF motor) is provided to convey the printing paper wound around the platen in synchronization with the printing operation. A pulse motor is used as this LF motor. A pulse for rotating the platen by a rotation angle corresponding to the line feed amount of the printing paper is supplied from the control unit to the LF motor at a predetermined timing. The LF motor rotationally drives the platen based on this pulse to feed the specified amount of printing paper.

After the line feed is completed, the LF
A constant holding torque is applied to the motor. This holding torque is a torque sufficient to prevent the printing paper from easily moving due to an external force, and is a torque that allows the operator to manually feed the printing paper. Actually, the holding torque is set to a value of about 1/5 to 1/10 of the rotation torque when the printing paper is fed by the LF motor.

By the way, as a pulse motor used for an LF motor or the like of a printer, for example, by stepwise controlling an exciting current supplied to two exciting coils, the two exciting coils combine as shown in FIG. There is a multi-phase excitation pulse motor in which a vector of a magnetic field is formed and a rotor is rotated by rotating the vector of the composite magnetic field. According to this multi-phase excitation type pulse motor,
The rotation angle of the rotor can be controlled at a predetermined unit angle.

Next, L using a multi-phase excitation type pulse motor
Regarding the conventional control method of the F motor, the processing procedure will be described with reference to the flowchart of FIG. The control is executed by the microprocessor. When the power of the entire apparatus is turned on, the microprocessor first performs the initial processing of the inside of the apparatus itself and other parts of the apparatus (step S51), and then the initial lock time T _C at the motor start and the motor stop time. The final lock time T _D is set (step S52). Next, a motor start command is issued to the motor drive circuit (step S53), then an initial lock time T _C is set and an initial lock process is executed (step S54), and then a constant speed rotation mode of the motor. (Step S5)
5). In the motor stop process, the microprocessor sets the final lock time T _D for the motor drive circuit (step S56), and then executes the motor stop process (step S57) to stop the LF motor.

FIG. 6 shows the relationship between the drive timing of the pulse motor used as the LF motor and the speed of the rotor. In the figure, the vertical axis shows the driving speed and the horizontal axis shows the time, and the driving state of n pulses from T ₀ to T _{n + 1} is shown. T ₀ indicates the initial lock time, which is (3), (8),-in FIG.
It is the time when the rotor is locked at any position of the magnetic field vector of (3),-(8). Subsequently, it accelerated from T ₁ to T _4, become constant speed state from T ₅ to _{T n-4, T n-} 3
To T _n, the motor is stopped after the final lock time of T _{n + 1} . In this case, the operation of the magnetic field vector in Fig. 4 is from the position (1) to (3) → (8) →-(3) → …… → (8)
→ It stopped at (10).

[0008]

However, in the above control method, the larger the difference in the ratio of the magnetic field vectors is (see FIG. 4).
(See Table 1 and Table 1), because the rotor of the LF motor becomes unstable, a step-out may occur at the next motor start depending on variations in motor performance, variations in load, or timing of motor start. There was a possibility. Therefore, the initial lock time is lengthened or the acceleration / deceleration is gently performed as shown by the broken line in FIG. 6 to prevent step-out caused by variations in motor performance, variations in load, motor start timing, and the like. But L
There is a problem that the throughput of the F motor is reduced.

Therefore, according to the present invention, there is a decrease in throughput caused by step-out caused by variations in motor performance, variations in load, timing of motor start, etc., lengthening of initial lock time, and slow acceleration / deceleration. It is an object of the present invention to provide a highly reliable and high throughput pulse motor control method.

[0010]

A pulse motor control method according to the present invention has an exciting circuit capable of independently controlling a plurality of exciting currents supplied to each of a plurality of exciting coils. Is a method for controlling a multi-phase excitation type pulse motor in which the rotor rotation angle is controlled by rotating the combined magnetic field vector formed by a plurality of exciting coils by a real multiple of a predetermined unit angle while switching the ratio of the above. At the start of rotation of the rotor, the position of the rotor with respect to the composite magnetic field vector at the previous stop is judged, and the lock time corresponding to the judgment position is set in the set lock time. Is supplied to the exciting coil.

[0011]

In the present invention, by supplying the exciting current to the exciting coil at a ratio corresponding to the magnetic field vector at the stop position at the lock time set according to the previous stop position of the rotor with respect to the combined magnetic field vector when the motor is started. , The position deviation of the currently stopped position of the rotor due to load fluctuation or the like is corrected, and the rotor is surely aligned with a predetermined stop position. Then, in the initial lock process, the rotor is locked at the position closest to the rotation direction, and the rotation of the rotor is started from the stable phase.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a flowchart showing a processing procedure of a pulse motor control method according to the present invention, and FIG. 2 is a block diagram of a control circuit of a printer to which the present invention is applied. First,
In FIG. 2, a bus line 1 includes a microprocessor 2, a ROM (read only memory) 3, a RAM (random access memory) 4, a drive circuit 5 for an LF motor 6, and an I / F (interface) controller. 7 and the printing unit 9 are connected to each other. The microprocessor 2 performs arithmetic processing for controlling the printer. R
The OM 3 is a memory for storing its operation program and the like, and the RAM 4 is a memory for storing various data necessary for operations such as calculation. The drive circuit 5 is a circuit that outputs a pulse for driving the LF motor 6. I
The / F control unit 7 is a circuit that takes in parallel data input from the host side via the I / F connector 8 and sends out predetermined information to the host side via the I / F connector 8. The printing unit 9 is composed of various mechanisms including a print head that performs predetermined printing on printing paper under the control of the microprocessor 2.

In the control circuit of the printer having such a configuration, when a print start command and print data are input from the host side to the I / F control section 7 via the I / F connector 8, the print data is stored in the RAM 4. It Then, the microprocessor 2 reads out the print data, generates a predetermined print signal, and drives the print unit 9. When the printing of one line is completed by this printing operation, the microprocessor 2 supplies a predetermined printing control signal to the drive circuit 5.
As a result, the LF motor 6 rotates by a predetermined rotation angle.

A specific circuit configuration of the drive circuit 5 of the LF motor 6 is shown in FIG. In the figure, the LF motor 6 is a two-phase excitation type pulse motor in which the rotor rotates by rotating the vector of the composite magnetic field formed by the pair of excitation coils 21 and 22. Each exciting coil 21,
To 22 are connected exciting circuits 31 and 32 capable of independently controlling the exciting current supplied to each. In FIG. 3, the exciting circuit 31 for controlling the exciting current of the exciting coil 21.
Although only the circuit configuration is shown, it is assumed that the excitation circuit 32 has the same circuit configuration.

The phase switching signal S ₁₁ is input to the input terminal 41 of the exciting circuit 31, and the control signal S ₁₂ for determining the current value of the exciting current is input to the input terminal 42. The exciting circuit 31 includes a D / A converter 4 for converting the control signal S ₁₂ into an analog signal.
3, a comparator 44 having this analog output as a non-inverting input, a monostable multivibrator 45 having the comparison output as a trigger input, and an output of the monostable multivibrator 45 and a phase switching signal S ₁₁ as two inputs. It has a gate circuit 46 and a switch circuit 47 for determining the on / off timing of the exciting current to the exciting coil 21 and its direction based on the four outputs of the gate circuit 46. Further, a feedback circuit 46 for monitoring the exciting current of the exciting coil 21 and guiding it as an inverting input of the comparator 42 is provided, and this feedback circuit 46 is composed of resistors R ₁₀ and R ₁₁ and a capacitor C ₁ . ing.

The gate circuits 46 are connected in series with each other and inverters 461 and 4 for inverting the phase switching signal S ₁₁ twice.
62 and an inverter 463 that inverts the phase switching signal S ₁₁
And the phase switching signal S ₁₁ and the monostable multivibrator 4
NOR gate 464 having 2 outputs of 5 and inverted output of inverter 461 and monostable multivibrator 4
It is composed of a NOR gate 465 which receives the output of 5 as 2 inputs. Switch circuit 47, transistor T ₁₁ ~
Consists T ₁₄ and diodes D ₁ to D _4, the gate circuit 4
Inverter 462, inverter 463, NO in 6
The outputs of the R gate 464 and NOR gate 465 are used as the base inputs of the transistors T ₁₁ , T ₁₂ , T ₁₃ and T ₁₄ .

Next, the circuit operation of the drive circuit 5 of the LF motor 6 having the above configuration will be described. First, the phase switching signal S
₁₁ is input and the potential of the input terminal 41 becomes "H" level, and at the same time, a digital signal (PWM signal) corresponding to a predetermined current value is supplied to the D / A converter 43 via the input terminal 42. The signal analogized by the D / A converter 43 becomes the non-inverting input of the comparator 44, so that the output of the comparator 44 rises. On the other hand, the monostable multivibrator 45 has a configuration in which its output is initially in the “L” level state and is triggered by the fall of the output of the comparator 45 to generate the “H” level output for a fixed time. ing.

When the "H" level signal is input to the gate circuit 46 via the input terminal 41 and the "L" level signal is input from the monostable multivibrator 45, the output of the inverter 462 is "H". Level, the output of the inverter 463 becomes "L" level, the output of the NOR gate 464 becomes "L" level, and the output of the NOR gate 465 becomes "H" level. As a result, in the switch circuit 47, the transistors T ₁₁ and T ₁₄ are turned on, and the transistors T ₁₂ and T ₁₃ are turned off. As a result, an exciting current flows in the exciting coil 21 in the direction of the arrow in the figure. On the other hand, when the potential of the input terminal 41 becomes “L” level, the transistors T ₁₂ and T ₁₃ are turned on, contrary to the above case,
The transistors T ₁₁ and T ₁₄ are turned off. As a result, an exciting current flows in the exciting coil 21 in the direction opposite to the direction of the arrow in the figure.

As is clear from the above description, the above L
According to the drive circuit 5 of the F motor 6, the exciting current in the direction according to the polarity of the phase switching signal S ₁₁ is supplied to the exciting coil 21 as a constant current according to the signal voltage of the non-inverting input of the comparator 44. It will be. Also, the exciting coil 2
As shown in FIG. 4, the two exciting coils 21, 2 are controlled by controlling the exciting currents supplied to the 1, 2, 22 stepwise.
The vector of the composite magnetic field formed by 2 can be rotated by a unit angle. As a result, the rotation angle can be controlled at a unit angle divided into an integral fraction of the minimum rotation angle of the conventional pulse motor.

Next, the processing procedure of the control method of the LF motor 6 executed by the microprocessor 2 will be described with reference to FIG.
It will be described in accordance with the flowchart of. When the power of the entire apparatus is turned on, the microprocessor 2 first carries out initial processing of the inside of the apparatus itself and other parts of the apparatus (step S11), and then the lock times T _{A to} T for driving the LF motor 6. _D is sequentially read from the ROM 3 via the bus line 1 and set in the internal register (step S12). Here, the lock time T _A is the magnetic field vector (1), (5), (6), (10),-(1),-(5),-(6),-(10) of FIG.
The pre-lock time and the lock time T _B when the motor is started from are the magnetic field vectors (2), (4), (7), (9),-(2),-of FIG.
The pre-lock time and the lock time T _C when the motor is started from (4),-(7),-(9) are the magnetic field vectors (3), (8),
The initial lock time and the lock time T _D when the motor is started from-(3) and-(8) are the final lock time when the motor is stopped.

Next, the microprocessor 2 issues a motor start command to the drive circuit 5 (step S1).
3) Then, it is judged whether or not the previous stop position of the rotor of the LF motor 6 is the position (3), (8),-(3),-(8) with respect to the combined magnetic field vector (step S14). ), If it is determined that these positions are not present, then the previous stop position of the rotor is the magnetic field vector (2), (4), (7), (9),-(2),-(4), -(7),-(9)
It is determined whether or not the position is (step S15).
It is assumed that the microprocessor 2 stores the previous stop position of the rotor with respect to the combined magnetic field vector.

In this judgment processing, the microprocessor 2 causes the magnetic field vectors (2), (4), (7), (9),-(2),-(4),-
If it is determined that the position is not at (7),-(9), the previous stop position of the rotor is the magnetic field vector (1), (5), (6), (10),-(1),
Since the positions are-(5),-(6),-(10), the pre-lock time T _A is set for the drive circuit 5 and the exciting current having a ratio corresponding to the magnetic field vector is applied to the exciting coil 21, 22 is performed (step S16), and the magnetic field vector
If it is determined that the position is (2), (4), (7), (9),-(2),-(4),-(7),-(9), the pre-lock time T _B And the exciting current of the ratio corresponding to the magnetic field vector is set to the exciting coil 2
A process of supplying the first and second units 22 and 22 is performed (step S17), and then the initial lock process mode is entered (step S1)
8). If it is determined in step S14 that the rotor position is the position of the magnetic field vector (3), (8),-(3),-(8), the process directly proceeds to step S18.

In step S18, after the initial lock time T _C is set and the initial lock process is performed, the microprocessor 2 shifts to the constant speed rotation mode of the LF motor 6 (step S19). In this constant speed rotation mode, control is performed to keep the exciting current supplied to the exciting coils 21 and 22 at a predetermined timing at a constant value. At the time of the motor stop processing, the microprocessor 2 sets the final lock time T _D to the drive circuit 5 (step S20), and thereafter issues a motor stop command (step S41), L
The F motor 6 is stopped. The categories from start to stop of the LF motor 6 have been schematically described above.

Next, the stop position of the rotor of the pulse motor will be described using the magnetic field vector of FIG. In addition,
In the example shown in FIG. 4, the angle (90
This is the case where the rotation control is performed at a unit angle in which (°) is further ⅕. Table 1 shows actual values of the exciting currents of the exciting coils 21 and 22.

[Table 1] When the exciting current of the exciting coil 21 and the exciting current of the exciting coil 22 are set to the ratios shown in Table 1, the vector of the synthetic magnetic field formed by the two exciting coils 21 and 22 becomes as shown in FIG. It will rotate by a unit angle (18 °).

Here, the ratio of the exciting current of the exciting coil 21 and the exciting current of the exciting coil 22 is as shown in Table 1. As is clear from Table 1, No. 1, 5, 6,
It can be seen that the larger the ratio is, the longer it takes for the rotor to stabilize at the unit angle θ. For this reason, it is necessary to set the prelock times T _A and T _B according to the ratio and to start the motor accordingly.

FIG. 6 shows the relationship between the drive timing of the pulse motor and the speed of the rotor. In the figure, the driving speed is plotted on the vertical axis and time is plotted on the horizontal axis, and the driving state of n pulses from T _0-1 to T _{n + 1} is shown. Here, each of the acceleration and deceleration T ₁ through T ₄ between the T _n-3 ~T _n are performed at 4 pulses between from T ₅ of fifth pulse (n-4) -th pulse of T _n-4 Is the constant speed driving period. The width of T _{0-1 to} T _{n + 1} is a time width corresponding to the application time of each pulse.

Here, T _0-1 indicates the prelock time,
It is set to correct the positional deviation due to load fluctuations etc. at the currently stopped position and to perform phase adjustment to the predetermined stopped position reliably, and 0, T _A , T _B is preset according to the stopped position. The time taken will be taken. In addition, T ₀ represents the initial lock time, which is locked at the position closest to the rotation direction of the rotor among the magnetic field vector positions (3), (8),-(3),-(8) in FIG. It is set to start from a stable phase for acceleration from T ₁ . T _{n + 1} is the final lock time, which is set to ensure the phase adjustment including the stable time following the state of the final n-th pulse that has been decelerated.

In FIG. 4, when starting from the position of the magnetic field vector (1), the rotor is driven by n pulses,
(1) → (3) → (8) →-(3) →-(8) → (3) → …… → (3) →
(8) → It rotates in the order of (10) and finally stops at the position of the magnetic field vector (10). In this case, the prelock time T _0-1 is as shown in FIG.
The prelock time T _A in the flowchart of FIG.
Next, at the initial lock time T ₀ , the stop position is moved from the position (1) to the next position (3) during the time T _C ,
After that, it is driven to the position (8) of the nth pulse and moved to the stop position (10) at the final lock time T _{n + 1} . The pulse application time of each of T _0-1 , T ₀ and T _{n + 1} is set so as to take about twice as long as one pulse response time.

As described above, (3), (8),-(3),-in FIG.
When rotating the rotor from the non-stable phase other than the stable phase, which is the magnetic field vector position of (8), the rotor is rotated to the stable phase after the prelock time T _{0-1 is} surely set to the predetermined stop position. By doing so, the motor can always be started from the stable phase.

In the above embodiment, the case where the invention is applied to the printer using the pulse motor as the LF motor has been described. However, the present invention allows the rotor to be formed by rotating the composite magnetic field vector formed by a plurality of exciting coils. It is applicable to all devices using a rotating multi-phase excitation pulse motor.

[0031]

As described above in detail, according to the present invention, the rotor position is determined at the time of motor start with respect to the magnetic field vector at the time of the previous stop, and the pre-lock process is performed according to the determined position, so that the rotor is rotated. Since it can always be rotated from the stable phase, variations in motor performance,
It is possible to prevent out-of-step due to load variation or motor start timing, etc., and to prevent a decrease in throughput caused by lengthening the initial lock time or gradual acceleration, thereby improving reliability and increasing throughput. ..

[Brief description of drawings]

FIG. 1 is a flowchart showing a processing procedure of a pulse motor control method according to the present invention.

FIG. 2 is a block diagram of a control circuit of the printer according to the present invention.

FIG. 3 is a circuit diagram showing a specific configuration of a drive circuit for the LF motor shown in FIG.

FIG. 4 is a vector diagram of a synthetic magnetic field generated by an exciting coil.

FIG. 5 is a flowchart showing a processing procedure of a conventional pulse motor control method.

FIG. 6 is a characteristic diagram showing a relationship between drive timing and speed of a pulse motor.

[Explanation of symbols]

1 Bus Line 2 Microprocessor 3 ROM (Read Only Memory) 4 RAM (Random Access Memory) 6 Line Feed (LF) Motor 21,22 Excitation Coil 31,32 Excitation Circuit 43 D / A Converter 44 Comparator 45 Monostable multivibrator 46 Gate circuit 47 Switch circuit 48 Feedback circuit S ₁₁ Phase switching signal S ₁₂ Excitation current control signal

Continued Front Page (72) Inventor Naoji Akutsu 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (1)

Claim: What is claimed is: 1. An exciting circuit having independent control of a plurality of exciting currents supplied to each of a plurality of exciting coils, wherein the ratio of the plurality of exciting currents is stepwise. A control method of a multi-phase excitation pulse motor for controlling a rotation angle of a rotor by rotating a composite magnetic field vector formed by the plurality of excitation coils by a real number multiple of a predetermined unit angle while switching, and comprising: At the start of rotation, the position of the rotor with respect to the composite magnetic field vector at the time of the previous stop is determined, and a lock time corresponding to the determined position is set, and the exciting current having a ratio corresponding to the determined position is set in the set lock time. A pulse motor control method characterized by supplying to a plurality of exciting coils.