JPH01283096A - Pulse motor control device - Google Patents

Abstract

PURPOSE:To enable the commonness of parts to be attained for an idle gear and a platen gear enabling various pin-shaped printing heads to be mounted by controlling a fine rotary angle only when a rotor starts and ends its rotation. CONSTITUTION:A pulse motor 6 consists of a two-phase excitation pulse motor which rotates a rotor by rotating a vector of compound magnetic field formed by a pair of excitation coils 41, 42. An excitation circuit, which enables an excitation current supplied to each coil 41, 42 to be variably independently controlled, is connected to each excitation coil 41, 42. This excitation circuit controls a fine rotary angle when the rotor starts and ends its rotation. When the rotor is in rotation excepting the time for the rotor to start and end its rotation, the excitation current, supplied to each excitation coil by the predetermined timing, is held to a fixed value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pulse motor control device that controls the rotation angle of a rotor of a pulse motor.

(Prior Art) <Background> Pulse motors are widely used in printers, facsimile machines, copying machines, and various other office equipment.

This pulse motor is capable of rotating the rotor by a certain rotation angle with one pulse, so it is suitable for conveying objects with high precision due to its good controllability.

Here, the operation will be explained using a printer using a pulse motor.

Printing paper is wrapped around the printer's platen, but
A line feed motor is provided to carry out so-called line feed in which the printing paper is conveyed in synchronization with the printing operation. This line feed motor also consists of a pulse motor. The line feed motor is supplied with a pulse from the host side at a predetermined timing to rotate the platen by a rotation angle corresponding to the amount of line feed of the printing paper. The line feed motor rotates the platen based on this pulse and conveys the print paper by a specified amount.

Further, after the line feed is completed, a constant holding torque is applied to the line feed motor. This holding torque is set to a torque sufficient to prevent the printing paper from easily moving due to external force, and a torque that allows the operator to manually feed the printing paper. . In reality, the holding torque is about 115 to 1/10 of the rotational torque when feeding the printing paper by the line feed motor.

<Printer Control Circuit> Now, FIG. 2 shows a block diagram of such a printer control circuit.

In the figure, path line 1 includes microprocessor 2.
, a read-only memory (ROM) 3, a random access memory (RAM) 4, a drive circuit 5,
An interface (I/F) control section 7 and a printing section 9 are connected. The microprocessor 2 is a circuit that performs calculations for controlling this printer. The read-only memory 3 is a memory for storing the operating program and the like. Further, the random access memory 4 is a memory for storing various data necessary for operations such as arithmetic operations. The drive circuit 5 includes a line feed motor (
This circuit outputs driving pulses to the LF motor (LF motor) 6. The interface control unit 7 is a circuit that receives serial data input from the host side via an interface connector (I/F connector) 8, and also sends predetermined information to the host side via the interface connector 8. The printing unit 9 is a part that is composed of a print head that performs predetermined printing on printing paper under the control of the microprocessor 2, and various mechanisms.

Motor Drive Circuit> FIG. 3 shows a specific wiring diagram of the drive circuit 5 for the line feed motor 6 in the circuit shown in FIG. 2.

In FIG. 3, a pulse motor 6 is a two-phase excitation type pulse motor, and is a motor that rotates a vector of a composite magnetic field formed by a pair of excitation coils 11 and 12 to rotate a rotor 13.

Moreover, this drive circuit is already a well-known circuit,
5 drive circuits 0~4 and 5 resistors R0~
R4 and five NPN transistors T0 to T4, a control signal S a ” S a is supplied to the resistor R
The rotor 13 is configured to rotate when the excitation coils 11 and 12 are excited at a predetermined timing when a switch circuit consisting of a PNP transistor T5, a PNP transistor T5, and a PNP transistor T5 is turned on.

The signals S I'' S a are input to the drive circuit at 0 to 4 through terminals 21 to 24. These signals are rotation control signals that are shifted from each other by π/2 in electrical angle.

Also, the signal S0 input from the terminal 2o, when the motor is rotating,
This is a signal that is intermittently supplied at a predetermined repetition frequency. This signal is a signal that is separately created to control the driving state of the motor, and essentially, if it is continuously turned on, the motor continues to be driven. On the other hand, if it is turned off continuously, the motor is stopped. Therefore, this signal S0 is 1
If a pulse is input, the rotor 13 will rotate by π/2 electrical angles.

The terminal 25 is a terminal that supplies a voltage for pulling up the output terminals 0 to 4 to the drive circuit. Further, the terminal 26 is connected to the excitation coil 11 when the transistor T is on.
．． ．． This is a terminal for supplying excitation current to 12. The rotor 13 is rotationally driven by this exciting current.

Further, when a predetermined voltage is applied to the terminal 27, a predetermined current is applied to the exciting coil 1 via the resistor R7 and the diode Do.
Delivered on 1.12. This voltage is applied to supply a holding current. That is, when the rotor 13 is stopped, any two of the transistors T1 to T4 are turned on, thereby supplying a holding current to the excitation coils 11 and 12. Therefore, the rotor 13 is held by a constant holding torque.

Now, returning to FIG. 2 again, when print data is input from the host side to the interface control section 7 via the interface connector 8, this print data is stored in the random access memory 4.

The microprocessor 2 then reads this print data, creates a predetermined print signal, and drives the print section 9. When one line of printing is completed, the microprocessor 2
supplies a line feed signal to the drive circuit 5. The drive circuit 5 receives the line feed signal and sends control signals S0 and S1 to the line feed motor 6 for a predetermined period of time.
~S4 (Figure 3) is supplied. As a result, the line feed motor 6 rotates by a predetermined rotation angle.

Motor and Reduction Mechanism> FIG. 4 is a plan view showing the deceleration mechanism of the line feed motor.

In the figure, a spur gear 31 provided on the output shaft of the line feed motor 6 meshes with a large diameter spur gear 32. This large diameter spur gear 32 is coaxially fixed to a small diameter spur gear 33. The small-diameter spur gear 33 meshes with a larger-diameter spur gear 34, and this large-diameter spur gear 3
4 is directly connected to the shaft 35 of the platen. Here, the spur gear 31 will be called a motor gear, the spur gears 32 and 33 will be called an idle gear, and the spur gear 34 will be called a platen gear.

When the line feed motor 6 is driven in this manner, the motor gear 31, idle gears 32, 33, and platen gear 34 reduce the speed at a predetermined reduction ratio, and the platen is rotated by a predetermined angle. Wire Configuration> Next, the print head provided in the print section 9 in FIG. 2 will be explained.

FIG. 5 is an explanatory diagram showing the configuration of the print wire of the print head.

In Figure 5, (a) is a 9-bin type, (b) is an 18-bin type with 9 bins arranged in two rows, (c) is the same, and (d) is a 24-bin type with 12 bins arranged in two rows. The condition of the printing wire of the shaped head is shown. In both cases, the vertical direction of the drawings is the conveying direction of the printing paper, and the horizontal direction is the scanning direction of the head. For example, in FIG. 5(a), nine printing wires are arranged at intervals of 1/72 inch (1 inch = 2.54 cm). Normally, when such a wire dot type print head is used, overlapping printing is performed so as to close the spaces between the printing dots in the vertical direction (as shown by the broken line circles in the figure). For this reason, the platen should be moved to one side of the printing wire spacing.
It becomes necessary to rotate by an integral multiple of /2. Therefore, the ability to drive the platen in 1/144 inch increments is required. The same applies to the daily bottle type shown in FIG. 5(b). In the case of FIG. 5(b), the two rows of printing wires are vertically offset from each other by 1/2 of their diameter, and in the case of FIG. 5(C), the printing wires are symmetrically arranged. Arranged. Furthermore, 2 shown in FIG. 5(d)
In a 4-bin type head, the printing wire is 1/9
Since the platens are arranged at 0 inch intervals, the ability to drive the platen in 1/180 inch increments is required. Note that some 24-bin heads are required to be capable of being conveyed in 1/120 inch increments.

In order to meet these demands, in the conventional case, for example, 1
A stepper motor is used that rotates 7.5 degrees per step.

Here, the torque characteristics of such a pulse motor will be explained.

FIG. 6 is a graph showing the relationship between the torque of the pulse motor and the number of rotations (speed) per unit time.

In the figure, when the rotational speed of the pulse motor is plotted on the horizontal axis, and if the maximum speed at which the pulse motor can follow the drive pulse is 100%, then the driving torque is 70% of the maximum speed.
If it exceeds %, it decreases rapidly. Therefore, a pulse motor is usually used at an operating speed of about 70% of the maximum speed.

(Problem to be Solved by the Invention) By the way, some printers are equipped with various print heads as shown in FIG. It is preferable that each part be used in common in order to reduce the number of parts.

For example, a printer equipped with a 9-bin type print head shown in FIG. 5(a) and a printer equipped with a 24-bin type print head shown in FIG. 5(d) are different from each other. Although different gear ratios are used for the spur gears 32 and 33 shown in Figure 4) and the platen gear (spur gear 34 shown in Figure 4), the line feed motor 6 is commonly used. Become. However, even with this, it is necessary to prepare separate parts for each model, such as the idle gear and platen gear, and the effect of reducing the number of parts cannot be said to be sufficient.Moreover, when the reduction ratio is changed, as shown in Figure 6, , there is a problem that the rotational torque of the motor increases or decreases. That is, if the torque of the motor decreases, the printing paper conveyance force of the platen becomes insufficient. vice versa,
As the torque of the motor increases, the holding torque also increases, which creates a problem in that it becomes difficult for an operator to manually rotate the platen.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a pulse motor control device that reduces the number of parts and eliminates problems such as insufficient torque and operability.

(Means for Solving the Problem) The pulse motor control device of the present invention provides a multiphase excitation type pulse motor that rotates a rotor by rotating a vector of a composite magnetic field formed by a plurality of excitation coils. The excitation circuit has an excitation circuit that independently and variably controls the excitation current supplied to each of the excitation coils, and this excitation circuit controls the ratio of the excitation current supplied to each of the excitation coils at the start and end of rotation of the rotor. The rotation angle of the rotor is controlled by switching the vector of the composite magnetic field formed by the excitation coil stepwise by a real number multiple of a predetermined unit angle. However, during the rotation of the rotor, the excitation current supplied to each of the excitation coils at a predetermined timing is maintained at a constant value.

(Function) The above device performs excitation current control similar to the conventional one while the rotor is rotating. On the other hand, depending on the ratio of excitation current supplied to the excitation coil at the start and end of rotor rotation, the rotor rotates by a predetermined unit angle that is further divided into several parts from the previously set minimum rotation angle. do. As a result, simply by controlling the excitation current supplied to the excitation coil, it is possible to mount various bottle-shaped print heads, and it is also possible to use the idle gear and the platen gear as common parts.

Furthermore, if the rotation is controlled by the unit angle only at the start and end of rotation of the rotor, the control circuit is burdened only at these times, and the decrease in throughput can be suppressed to the utmost.

(Embodiment) Motor Drive Circuit> FIG. 1 is a wiring diagram of an embodiment of the pulse motor drive circuit of the present invention.

In the figure, the pulse motor 6 is a two-phase excitation type pulse motor that rotates a rotor by rotating a vector of a composite magnetic field formed by a pair of excitation coils 41 and 42. Each of the excitation coils 41 and 42 is connected to an excitation circuit that can independently and variably control the excitation current supplied to each excitation coil.

In the embodiment shown in FIG. 1, only the excitation circuit that controls the drive current supplied to the excitation coil 41 is illustrated, and the illustration of the excitation circuit 42 is omitted because it has the same configuration.

This excitation circuit is supplied with a signal Sll corresponding to the control signals 81 to S4 explained in FIG.
A control signal S1□ that determines the current value of the excitation current supplied to the excitation coil 41 is supplied from the excitation coil 41. This circuit is a D/A conversion circuit 4 that converts the control signal S12 into analog.
4, a comparator 45, a monostable multivibrator 46, and a gate circuit 50. Further, a switch circuit 6o consisting of transistors T to T14 and diodes D1 to D4 is provided for determining the on/off timing and direction of the excitation current to the excitation coil 41. Furthermore, a feedback circuit is provided for monitoring the excitation current supplied to the excitation coil 41 and guiding it to the inverting input terminal of the comparator 45, which includes a resistor R1°, a resistor R1! and capacitor C
1. Note that the gate circuit 50 includes three inverters 51, 52, 53 and two NOR gates 5.
4.55.

<Basic operation of operating circuit> The pulse motor drive circuit shown in FIG. 1 operates as follows.

First, the control signal Sl+ to drive the motor is input from the terminal 47, and when the terminal 47 becomes high level, the terminal 4
3, a digital signal (PWM signal) corresponding to a predetermined current value is input to the D/A converter 44. As a result, the analog-converted signal is input to the non-inverting input terminal of the comparator 45, and the output of the comparator 45 rises. The monostable multivibrator 46 is a circuit whose output is initially set to a low level, and is triggered by the fall of the comparator 45, and whose output is set to a high level for a certain period of time.

In this way, when a high level signal is input to the gate circuit 50 from the terminal 47 and a low level signal is input from the monostable multivibrator 46, the output of the inverter 52 is high level, the output of the inverter 53 is low level, and the output of the NOR gate 54 is The output of the NOR gate 55 becomes low level and high level. Therefore, in the switch circuit 60, transistors Tll and T14 are turned on. As a result, an excitation current flows through the excitation coil 41 as indicated by an arrow 61 in the figure. The voltage proportional to this current becomes the terminal voltage of the resistor R1° of the feedback circuit, and this voltage
It is fed back to the inverting input terminal of comparator 45 via LI. In the switch circuit 60, after the transistors T1□ and T14 are turned on, the excitation current of the excitation coil 41 gradually increases.

Figure 7 shows the situation.

At time t0, the switch circuit is turned on, and at time t1, the detected current value exceeds the set current value input to the non-inverting input terminal of comparator 45. This causes comparator 45
output falls. At this timing, the output of the monostable multivibrator 46 becomes high level, and the output of the NOR gate 55 switches to low level. Gate circuit 50
Other outputs remain unchanged. As a result, transistor T14
is turned off. When the transistors T and 4 are turned off and the excitation current of the excitation coil 41 disappears, the detection signal from the resistor R1° disappears, and the comparator 45 raises its output again. On the other hand, monostable multivibrator 46
The output becomes low level after a certain period of time Δt, turning on the transistor T14 again.

Such an operation is repeated until the time shown at time t in FIG. 7, and a constant current value is maintained, and at time t, the control signal Sll input from the terminal 47 in FIG. 1 becomes low level. . As a result, the transistor Tll is turned off and the excitation current of the excitation coil 41 becomes zero. Note that the diodes D+ to D4 are connected to the transistors T1 and T14 in this way.
is provided to bypass the current that continues to flow through the exciting coil 41 when the excitation coil 41 is turned on or off.
This is a protection diode.

Now, in FIG. 1, this time the terminal 47 of the gate circuit 50
The human power from
Transistor T,2 turns on, transistor T1. turns on. Depending on the angle, the four excitation coils are marked with arrow 61.
An excitation current flows in the opposite direction. Time t shown in Figure 7
The operations after 4 are the same as those from times t1 to t4 described above.

That is, according to the pulse motor drive circuit shown in FIG. 1, a constant current is supplied to the exciting coil 41 in accordance with the signal voltage for current control input to the input terminal of the comparator 45.

<Stepwise rotation angle control> Now, in order to rotate the pulse motor 6 shown in FIG. 1 by a predetermined unit angle, the excitation current supplied to the excitation coils 41 and 42 is controlled in steps. Explain how.

FIG. 8 shows a control signal S11 that controls the current direction of the exciting coil 41 shown in FIG. 1, a control signal StZ that controls the current value, and a control signal S21 that similarly controls the current direction of the exciting coil 42. 2 is a timing chart showing changes in the level of the control signal Ski and the control signal Ski that controls the current value.

As shown in FIGS. 8(a) and 8(c), the control signals S ll+ S 21 for controlling the direction of the excitation current supplied to the two excitation coils 41 and 42 (FIG. 1) are each expressed in electrical angle. They are set to be shifted from each other by π/2. On the other hand, the signal S1 for controlling the excitation current of each excitation coil 41, 42
□, 822 are supplied so that they are periodically increased or decreased in stages over time. This t is set to 1/10 of the repetition period of the signal 5ilo 822 for controlling the direction of the excitation current. That is, the pair of excitation coils 41 and 42 of the pulse motor 6 shown in FIG. 1 are simply used in FIG. 8(a).

When only the control signals S+t and S2□ that alternately reverse the current as shown in (C) are supplied and a constant current is supplied for control, the pulse motor is activated every 5t/2 hours as before. It will rotate by π/2.

However, as shown in FIGS. 8(b) and 8(c), the ratio of the excitation current supplied to each excitation coil 41, 42 increases or decreases in stages over time. By switching in this manner, the rotor of the pulse motor can be rotated in small increments of 115 angles of π/2. Therefore, in this embodiment, the rotation angle of the rotor can be controlled by an angle corresponding to an integral multiple of 115 of π/2.

Here, Table 1 below shows the line feed pitches of various bottle-shaped print heads when a predetermined line feed pitch is set in the deceleration mechanism shown in FIG. 4 and this is used as a reference mechanism.

Table 1 According to this Table 1, for example, if the line feed pitch of the reference mechanism is 1/360 inch and the required line feed pitch of the print head is 17360 inches, one pulse will
/380 inch line breaks are achieved. However, 1/28
If a line break pitch of 8 inches is required, 1 and 1/
The line break will be accomplished by a pulse of 4.

Therefore, the angle rotated by one conventional pulse is further reduced by 1/
It is required that this pulse motor be rotated by a unit angle of 4.

In the example shown in Figure 8, the reference mechanism is line feed pitch 1/288.
This figure shows the case of an inch type, and the rotation angle can be controlled in unit angles, which is an additional 115 degrees compared to the conventional angle rotated by one pulse. It can be seen from Table 1 that in this way, it is possible to correspond to line feed pitches of all types of machines.

Next, Table 2 shows the actual values of the excitation current of each excitation coil shown in FIG. Further, FIG. 9 shows the vector of the magnetic field formed by the pair of excitation coils 41 and 42 (FIG. 1) when such current values are set.

Table 2 However, I: Excitation current ratio of excitation coil 41 II: Excitation current ratio of excitation coil 42 θ: Vector angle of magnetic field As shown in Table 2, excitation current of excitation coil 41,
When the excitation current of the excitation coil 42 is set to the ratio shown in this table, the vector of the magnetic field formed by the two coils rotates by a unit angle as shown in FIG.

For example, if we try to form a magnetic field vector in the direction shown by ■ in FIG. 9, the ratio of the exciting current of the exciting coil 41 and the exciting current of the exciting coil 42 is 0.988:0.1.
It becomes 56. Then, the ratio of the excitation current of the excitation coil 41 and the excitation current of the excitation coil 42 is set to 0.891:0.45.
4, the vector of this magnetic field becomes unit angle 186
counterclockwise and face the direction shown in Figure 9 (■). As a result, the motor axis of the pulse motor is 18 degrees in electrical angle.
It will be rotated increments. In the case of a conventional pulse motor, the vector of this magnetic field rotates by π/2 in the order of ■, ■, -■, -■. In the embodiment of the present invention, one step is divided into 115 steps.

<Torque characteristics of the motor> By the way, looking at Table 2, the excitation current of the excitation coil 41 is selected to be cos θ, and the excitation current of the excitation coil 42 is selected to be sin θ, and since CoS θ”+sin θ2 is always 1, The vectors of the magnetic fields all have the same magnitude.Therefore, the driving torque of the pulse motor can always maintain a constant value in this case.

When the control current shown in FIG. 8 is supplied in the manner described above, the drive circuit shown in FIG. 1 rotates the pulse motor by a unit angle.

In addition, when supplying a control current as shown in FIG. 8 in the circuit of FIG. 1, the current value when the pulse motor is stationary is about 115 to 1/10 lower than when the pulse motor is being driven. There is a possibility that so-called holding torque may be reduced.

This includes a method of controlling the PWM signal supplied to the D/A converter 44 to be changed between when the pulse motor is driven and when the pulse motor is stopped, and a method of switching the power supply supplied to the D/A converter 44. It is possible to set the holding torque to a sufficient value using these methods.

In this way, according to the circuit shown in Fig. 1, it is possible to control the rotation angle in unit angles obtained by dividing the minimum rotation angle of a conventional pulse motor into integer parts. The torque characteristics of the engine are also improved. Note that this number of divisions does not necessarily have to be an integer, but may be a real number.

FIG. 10 shows an explanatory diagram of the torque characteristic improvement effect.

In the figure, the horizontal axis represents ■~■ and -■~- shown in Figure 9.
The magnetic field vector of steps up to [phase] is shown, and the vertical axis shows the driving torque exerted on the rotor at each step. For example, in step (2), the driving torque increases to the maximum value T0 and increases and decreases in a sinusoidal curve. Here, when the number of divisions is the number shown in FIG. 9, the driving torque exerted on the rotor is To as shown in the graph of FIG.
It fluctuates up and down between and T1. On the other hand, in the conventional method of rotating the pulse motor in steps of π/2, the driving torque fluctuates between to and t2, and the range of fluctuation becomes very large.

That is, in the present invention, the torque ripple can also be made very small.

<Specific Operation of the Apparatus of the Present Invention> By the way, if the above control is directly applied to the line feed motor of a printer, the following problem will occur.

That is, the control signal 5ill supplied to the circuit shown in FIG.
5I215211 Sz□ are all generated by the microprocessor that controls the printer.

However, this microprocessor simultaneously receives data from the interface, processes the received data, controls spacing, etc. Particularly during line feeding, the amount of processing tends to increase.

Therefore, generating complex control signals during line feeding increases the burden on the microprocessor and reduces data processing capacity, ie, throughput.

Taking this point into consideration, the apparatus of the present invention performs the control shown in the above embodiment only at the start and end of rotor rotation, which require minute rotation angle control.

While the rotor is rotating, conventional control is performed as much as possible.

Next, the specific operation of the apparatus of the present invention will be explained with reference to the drawings.

FIG. 11 is a graph showing the relationship between the drive timing of the pulse motor and the speed of the rotor.

This graph shows the driving speed on the vertical axis and time on the horizontal axis, and T
The drive state of n pulses from o to T n *1 is shown. Here, acceleration and deceleration are T1 to T4 and T, respectively.
The driving is performed using four pulses from n-3 to Tn, and the period from the fifth pulse T8 to the n-4th pulse Tn-4 is a constant speed drive period. And T.

The width of ~T n *1 is described in correspondence with the application time of each pulse.

Here, To indicates the initial lock time, which is provided to correct deviations due to load fluctuations in the currently stopped position and to ensure matching. T n + 1 is the final lock time, which is provided to ensure matching including the stabilization time following the state of the final n-th pulse that has been decelerated.

In this embodiment, the above-mentioned minute rotation angle control is performed, for example, at To-
1 to To and Tn to T n +1.

It is assumed that at the time of To-8, the control pulse is in a holding state where no control pulse is output.

Now, the original model that does not require minute rotation angle control (see Table 1,
Let A be the model in which the line feed pitch is "l". In this case, the rotor is stopped at position ■ in the magnetic field vector diagram in Figure 9, and when driven by n pulses, ■ -〇-(-■)-
Assume that it rotates as (-■)... and stops at position ■. On the other hand, other models that require minute rotation angle control (models where the line feed pitch is other than "1" in Table 1) are designated as B.

In this case, it is assumed that the rotor is also stopped at the position (■) in FIG. 9. This rotor is driven by n pulses, rotates as ■-■-■-(-■)-(-■)...■-■, and finally stops at the [phase] position.

That is, in the case of A, the initial lock T0 is performed at the position ■ as usual, and thereafter the pulse is switched in the order ■-(-■)-(-■)-〇-〇..., and the nth pulse becomes the position ■. Final lock T. , also ■
I'm doing it.

On the other hand, in case B, the stop position is moved from ■ to the next position ■ at the initial lock To, and then, as in case A, it is driven to the position ■ of the nth pulse, and the final lock T
At n*1, move to the stop position [phase]. Each pulse application time of To and T n + 1 is 1
The time should be approximately twice the pulse response time.

Therefore, sufficiently accurate and stable control is possible for a moving distance within one pulse (in the case of the above embodiment, within 2/2 π in electrical angle).

In addition, the above-mentioned minute rotation angle control is performed near the start and end of rotation, for example, between To and T1, and between Trt-1 and T.
It may be done between n.

By performing the above-described control, the time required to perform minute rotation angle control, which is relatively complicated, is extremely short, and an increase in the burden on the control device can be prevented.

Although the present invention has been described with respect to a two-phase excitation type pulse motor, it can be similarly applied to a multi-phase excitation type pulse motor such as a four-phase excitation type.

(Effects of the Invention) According to the pulse motor control device of the present invention explained above,
The rotation angle can be controlled in finer unit angles than when the rotation is controlled simply by turning on and off the current supplied to a plurality of excitation coils. Therefore, if this is applied to a printer or the like, there is no need to change the gear ratio depending on the bottle shape of the installed print head. In addition, the torque ripple characteristics during driving can be improved, making it possible to apply it to an extremely wide range of fields.

Furthermore, according to the present invention, since the minute rotation angle control is performed only at the start and end of rotation of the rotor, there is an advantage that the burden on the control device is not significantly increased.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the pulse motor drive circuit of the present invention, Fig. 2 is a block diagram of a conventional printer control circuit, Fig. 3 is a wiring diagram of the line feed motor drive circuit, and Fig. 4 is a block diagram showing an embodiment of the pulse motor drive circuit of the present invention. The figure is a front view of the deceleration mechanism of the line feed motor, FIG. 5 is an explanatory diagram showing the configuration of a conventional printing wire, FIG. FIG. 8 is a waveform diagram of the drive current supplied to the pulse motor, FIG. 8 is a timing chart of the control signal supplied to the pulse motor drive circuit of the present invention, and FIG. 9 is a diagram of the magnetic field formed by the excitation coil in the pulse motor of the present invention. FIG. 10 is a graph illustrating its torque characteristics, and FIG. 11 is a graph illustrating the relationship between the drive timing and speed of the pulse motor, illustrating the specific operation of the apparatus of the present invention. 6...Pulse motor, 41.42...Exciting coil,
44...D/A converter, 45...Comparator, 46...Single, stable multivibrator, 50...
Gate circuit, Tll to T14...transistor, D1
~D4...Diode, RIon R11...Resistor, C1...Capacitor. Patent applicant: Oki Electric Industry Co., Ltd.
c) No. 6-

Claims (1)

[Claims] In a multiphase excitation pulse motor that rotates a rotor by rotating a vector of a composite magnetic field formed by a plurality of excitation coils, the excitation current supplied to each of the excitation coils is independently supplied to each of the excitation coils. It has an excitation circuit that performs variable control, and this excitation circuit changes in stages the ratio of the excitation current supplied to each of the excitation coils at the start and end of rotation of the rotor. The rotation angle of the rotor is controlled by rotating the vector of the composite magnetic field by a real number multiple of a predetermined unit angle. A pulse motor control device that maintains an excitation current supplied to a motor at a predetermined timing at a constant value.