JPS5932396A - Driving method for stepping motor - Google Patents

Abstract

PURPOSE:To turn the stepping motor stably without reversing the direction of rotation by generating predetermined torque to wire tension. CONSTITUTION:Torque is extremely small for time to-tp for a carriage suspension period (to-tm), but wire tension itself does not increases yet, and the revolution of the stepping motor is not reversed. There is a trough of zero torque by the changeover of phases at time t1, and the decrease of substantial torque is not avoided just after time t1, but the motor is not reversed because torque is extremely large just before time t1. Large torque in an extent against maximum wire tension is generated at time tm when a carriage starts its movement, and the revolution of the stepping motor is not reversed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for driving a stepping motor suitable for printers and the like.

Conventionally, in printers, a stepping motor has been used as a drive source for one carriage in order to accurately position the carriage.

The stepping motor rotates by an exact predetermined angle for each supplied pulse, and therefore, in order to move the carriage a predetermined distance, the stepping motor only needs to be rotated by the rotation angle corresponding to the predetermined distance. ,
The moving distance of the carriage can be accurately regulated by the number of supplied pulses.

By the way, the stepping motor has human phase and C phase.

The current is switched in the four phases of B phase and D phase, and the A phase and B phase, C phase and D phase are 180 degrees different from each other, and the two phases form a set and are energized and excited at the same time. Rotates by a predetermined angle each time. In other words, the physiognomy and C phase are simultaneously ′
A period of excitation with electric current (hereinafter, the combination of human phase and C phase is called AC)
phase), a period in which the B phase and C phase are simultaneously energized and excited (hereinafter, the combination of B phase and C phase is referred to as BC phase), and a period in which the human phase and D phase are simultaneously energized and excited. (Hereinafter, the combination of human phase and D phase will be referred to as AD phase).
(referred to as phase D). The stepping motor torque generated by the AC phase, BC phase, AD phase, and BD phase has a phase shift of 90 degrees due to the arrangement of the coils to which the current of each phase is supplied, and approximately has the characteristics of a dizziness wave. I am doing it.

On the other hand, as a driving method for a stepping motor, instead of supplying pulses from the outside, a sensor is installed in the stepping motor, and a predetermined pulse ( Closed-loop driving is performed in which a sensor pulse (hereinafter referred to as a sensor pulse) is generated and the current supply to each phase is switched using the sensor pulse.

FIGS. 1A, 1B, and 1C are timing charts showing an example of a conventional stepping motor driving method.

In the figure (α), torque AC due to the AC phase.

Torque BC due to BC phase, torque AD due to AD phase, B
As mentioned above, the torque BD due to the D phase has a sequential phase difference of 90 degrees, and when the torque is positive, the stepping motor rotates to the right, and when the torque is negative, the stepping motor rotates to the left. shall be.

Therefore, when rotating the stepping motor in the right direction, it is sufficient to always generate a positive torque, and by switching the torques AC, BC, BD, and AD in that order, the torque A as shown by the solid line can be obtained.

The energization of the C, B, and D phases is switched. However, as shown in FIG. 1(h), at time t at startup. The A and C phases are energized from tl to tl, the B and C phases are energized from tl to t, the B and D phases are energized from t to t, TB Gara 1. The A phase and the D phase are energized until then, and thereafter each phase is sequentially switched and energized.

Figure 1 (C) shows the sensor pulse, which is generated when each torque becomes zero and is used to switch the energization of the C, B, and D phases.In addition, each torque in Figure 1 (α) The curves originally correspond to the distance, that is, the rotation angle of the stepping motor's rotor, but for the sake of explanation, we assume that the rotor is rotating, and the rotation angle changes over time, so each torque curve is Shown as a function of time. The same applies below.

By the way, when supplying current to the coils of each phase of a stepping motor, switching from one phase to another causes a delay in the rise of the current, resulting in a steep rise of the current as shown in Figure 1(b). Must not be. For this reason, the torque is also the first
When switching at the timing shown in the figure, a large torque cannot be obtained due to the positional relationship between the rotor of the stepping motor and the rotor.

Therefore, in order to solve this problem, the switching timing is delayed to generate a torque as shown in FIG. 2 (α). In addition, in the same figure (OL),
The dotted line shows the actual torque due to the delay in the rise of the current,
Such torque increases sequentially. Figure 2(b) is shown in Figure 2(b).
The energization period of each phase of A, C, B, and D for generating the torque α) is shown, and the timing is shifted by one energization period with respect to FIG. 1(b). That is, in FIG. 1(b), starting from the AC phase, BC, BD, AD, etc.
. . . The switching is performed in the order of the phases, whereas in FIG.

However, according to this driving method, at startup (1 o
), the torque is zero and the increasing slope of the torque is slow, so the rotating direction of the stepping motor is not fixed and the actual driving is in a very unstable state.

In order to solve this problem, a driving method has been proposed that generates the torque shown in Figure S13. In addition,
The dotted line shows the actual torque due to the delay in the rise of the current.

In FIG. 3, electricity is applied to the phase in which the torque curve rises relatively quickly during the period from time 1o at startup to time t1. That is, first, at startup, it starts from the AC phase, and then, as shown in FIG. 2 (G), the BD, AD, and AC phases are
, Be, BD, . . . phase. As a result, the stepping motor can now be started at high speed and driven with large torque.

However, when a driving method using a stepping motor used in a printer is adopted, the carriage is driven at a speed of 1! It has been found that the following problems occur due to # configuration.

FIG. 4 is a configuration diagram showing an example of a carriage drive device of a conventional printer, where l is a drive pulley, 2 is a carriage, 3 is a wire, and 4 is a pulley.

In the figure, both ends of the wire 3 are fixed to the front and rear walls of the housing of the carriage 2, and are wound around the drive pulley 1 through a pulley 4.

The drive pulley 1 is rotated by a stepping motor (not shown), and as a result of this rotation, the carriage 2 is pulled by a wire 3 and moves in either direction.

By the way, the wire 3 and the casing of the carriage 2 are not completely inelastic, and for this reason, the period from when the stepping motor starts and the drive pulley 1 begins to rotate until the carriage 2 actually moves (hereinafter referred to as , referred to as the carriage stop period), the wire 3 stretches and the casing of the carriage 2 deforms, albeit slightly. However, an increasing tension is generated in the wire 3, and this causes a rotational force to be applied to the drive boob IJ-1, and thus to the stepping motor in the opposite direction to the direction in which it is intended to rotate. The above-mentioned tension reaches its maximum at the moment when the carriage 2 starts moving, and at this moment, static friction changes to dynamic friction in the carriage 2, and the tension becomes sufficiently small.

On the other hand, as shown in Figure 3, the torque of the stepping motor has a valley where it becomes zero, and the torque is small for a while after the phase is switched. Therefore, wire 3
If the torque is small during the carriage stop period when the tensilon of the carriage 2 is gradually increased, the rotational direction of the stepping motor may be reversed, making it impossible for the sensor to operate once and move the carriage 2 a predetermined distance.

Now, in Figure 3, time 1. The carriage stop period is from tIll to tIll. In fact, in printers,
The carriage 2 (Fig. 4) starts moving at the same rotation angle of the stepping motor that corresponds to a point slightly past time t. Therefore, the wire tension increases sequentially from time 1 until time tl! Suppose that it is maximum at I. On the other hand, since the torque becomes zero at time t1, the stepping motor reverses its direction of rotation.

Therefore, as shown in FIG. 5(l), the BC phase is switched from time t1 to tn to increase the torque during that period, and the switching point between the C phase and D phase is set later than time t1. A driving method has been proposed in which the torque is set to 0 (Fig. 5 (b)), but as shown by the dotted line between times tlotn, the torque actually obtained is sufficiently small, and the above problem cannot be solved. .Furthermore, at the time tm when the maximum tensilon of wire 3 (Fig. 4) is generated, only a substantially small torque near the torque valley is generated, so the above problem still remains. It turns out.

An object of the present invention is to eliminate the drawbacks of the prior art described above, prevent the rotational direction of the stepping motor from being reversed during the carriage stop period, and enable stable rotational movement to accurately and quickly move the carriage a predetermined distance. An object of the present invention is to provide a method for driving a stepping motor that can be moved.

In order to achieve this object, the present invention switches the energization period of a predetermined phase so that a predetermined torque is generated in the stepping motor with respect to the increasing wire tension during the stop period. Characterized by points.

Hereinafter, *m examples of the present invention will be explained with reference to the drawings.

FIGS. 6(α), (b), and (C) are timing charts showing an embodiment of the stepping motor driving method according to the present invention.

Figure 6 (α) shows the torque of the stepping motor, and the period from time to to tm is the carriage stop period, and at time Lm the carriage starts to be driven, and at the same time, the tension of the wire is At the time of start-up (tO), it is excited by the AC phase and started rapidly. For example, time 1p, 1 millisecond after startup
Switch to BC phase with . A torque that increases sequentially is generated by the BC phase, and #! at time t1. When the first sensor pulse occurs (16@(c)).

Switches to BD phase. A torque that increases sequentially is generated by the BD phase, and even if the sensor pulse of M2 is generated at time t, (
FIG. 6(C)) Excitation by the BD phase for a predetermined period, for example,
Extend the carriage stop period by 1 millisecond (to'=tm)
At time tq, which has passed, the phase is switched to the AD phase. From then on, time 1.
, 1. Part 3. Occurrence of the fourth sensor pulse (
In Figure 16 (C)), the phase is switched to the 1st-order Ac phase and BC phase, but
When the fifth sensor pulse occurs at time t11 (
(Fig. 6(C)), switch to the AC phase until time tr to generate torque in the opposite direction in the stepping motor, then switch to the Be phase again from time tr so that the sensor is at the hold position at time t6. Stop the stepping motor.

In the above driving, time t at the time of startup. , 19 minutes is intended for rapid startup, so apart from this period,
During the remaining period, the stepping motor is driven by sequentially increasing torque. Then, the carriage stop period (to
~tm), the torque is extremely small between times to and 19 (of course, it is not a problem for rapid startup), but the wire tension itself has not yet increased, and the rotation of the stepping motor does not reverse. . In addition, there is a valley of zero torque due to phase switching at time ITS, and a decrease in the actual torque is unavoidable immediately after time t8Jt1, but the torque becomes extremely large just before time t1, and as a result, the torque decreases near time t1. No reversal of rotation of the stepping motor occurs. Roughly speaking, at time I'11 when the carriage starts moving, a torque large enough to resist the maximum wire tension is generated, and the rotation of the stepping motor does not reverse. In the end, the stepping motor will operate stably.

In order to reduce this torque, the energization of the ^, C, B, and D phases is switched as shown in Figure (b) of %I6. Such switching is performed using sensor pulses (FIG. 6(C)).

That is, from the time of startup (to) until time tp, the A phase and C phase
The B phase and the C phase are energized from time tp to time t. At time tl, the C phase and D phase are switched, and the B phase and D phase are energized until time t. At time tq, the B phase and human phase are switched, and the A phase and D phase are energized until time t. Below, time 13.1. Between physiognomy and C
Also, between time t◆ and t6, phase B and phase C are '
A will be charged. But time! During some times t, tr between 4**6, the human phase and the C phase are temporarily energized, causing a reverse torque to be generated in the stepping motor as described above.

FIG. 7 is a pull diagram showing a specific example of the drive current generation circuit for each phase shown in FIG. 6(b), in which 5 is an input terminal;
6.7 is an inverter, 8 is a down counter, 9 is an up counter, 10 is a sensor circuit, 11 is a sensor%12
, 13.14 is a comparison circuit %15-16.17 is a timer,
18 is a NOR circuit, 19 is an OR circuit, 20 is a 4-bit shift circuit, 21 is an initial pattern generation circuit, 22 is a reset circuit, 23 is a buffer, and 24 is a stepping motor.

FIG. 8 is a timing chart for explaining the operation of FIG. 7, and each time on the one time axis corresponds to FIG. 6, and the symbols representing the signals of each part in FIG. 7 are used. hand,
This corresponds to the signal shown in FIG.

Next, the operation of this specific example will be explained.

In Figure 7 and Figure 8, time t. When a start pulse is input from the input terminal 5, the down counter 8 is preset to the value X, and the up counter is cleared. Further, the start pulse is supplied to the timer 17, inverted by the inverter 6, and supplied to the OR circuit 19 as T: /4A//(α).

On the other hand, the initial pattern generator rrilu 21 generates a 4-bit initial pattern in response to a signal from the G circuit 22, and the 4-bit shift circuit 820 is preset to the initial pattern. The 4-bit shift circuit 20 includes, for example, a register that shifts each bit in a ring shape, and has output terminals A, C, and B.

A 4-bit output is generated from D. And OR circuit 1
At each rising edge (leading edge) of the pulse supplied from 9 to the right shift terminal sR, the output terminals are shifted one bit to the right, that is, in the order of output terminals A - + O - + B - + D - + A, and The rising edge (leading edge) of the pulse signal supplied to the left shift terminal SL during the first comparison jli513
Shift left by 1 bit, that is, output terminal A −+
Shift is performed in the order of D-*B→C-+A. Incidentally, the A-phase driving current of the stepping motor 24 is generated from the output terminal A of the 4-bit shift circuit 20, and the following will be described below.
C, B from output terminals C, B, and D.

It is assumed that a D-phase drive current is generated.

Therefore, first, the 4-bit shift circuit 20 outputs the output terminals A and C by presetting the initial pattern.

The output levels of B and D are "1", "O", and "Q", respectively.

It becomes “1”. Here, the output level "1" is a high level, indicating that a drive current has been generated, and the output level "1" is a high level, indicating that a drive current has been generated.
0" is a low level and indicates that no drive current is generated.Hereinafter, for convenience of explanation, output terminals A, e, B,
For example, if the output levels of D are collectively expressed as a 4-bit pattern and the above initial pattern is preset, the output of the 4-bit shift circuit 20 will be expressed as "1, 0, 0.
゜1''. In this case, the first bit "l" indicates the output level of the output terminal A, and the second and third bits
The th and fourth bits "0", "01°, . . . represent the output levels of the output terminals C, B, and D, respectively.

Immediately after the 4-bit shift circuit 20 is preset to the turn after the 1 vJ period, the first pulse (time to) of the output pulse j due to the pulse α is supplied from the OR circuit 19 to the right shift terminal 8R, and the preset is completed. The initial pattern is shifted to the right by one bit. However, the output of the 4-bit shift circuit 1820 is 1, '1, 0, O''.
As a result, a drive current is generated at output terminals A and C. The driving current is supplied to the stepping motor 24 through the buffer 23, and the stepping motor 24 is driven and rotated in the AC phase (between t0 and t1 in FIG. 6).

The start pulse is also supplied to the timer 17 to operate it. The timer 17 generates a pulse V at time tp after a certain period of time has elapsed from the start of the operation. Pulse 1 is supplied to the OR circuit 19, and the IIFth pulse (time tp) of its output pulse is generated, resulting in a 4-bit shift [al
120 right shift) is supplied to terminal 8R. Therefore, the 4-bit shift@path 20 performs a 1-bit right shift and one output becomes 0°1.1.0". However, the output terminal C,
A drive current is generated in BC, and the stepping motor 24
It will be driven by the phase (m6 between Figure 1p and 11).

When the stepping motor 24 is further driven to rotate and the sensor 11 generates a sensor pulse, the sensor circuit 1o shapes the waveform of this sensor pulse and generates a pulse b. Pulse b is a low level, ie, “θ” pulse, and its falling edge (leading edge) sets the down counter 8 to 1.
(Hereinafter, “Numbers not surrounded by 0 are decimal numbers.”)
count down, and also set the up counter 9 to 1.
only count up. The count number of the down counter 8 is supplied to a comparison circuit 12.13, and the count number of the up counter 9 is supplied to a comparison circuit 14.

Different reference values are set in the comparison circuits 12, 13, and 14, respectively, and when the reference value and the supplied count number do not match, the comparison circuit 12 outputs #111. When they match, the comparator circuits 13 and 14 generate an output signal of 0'', and conversely, when they do not match, they generate an output signal of "O", and when there is a mismatch, they generate an output signal of "1". The reference value is equal to the count number when the down counter 8 counts down by 6, the reference value of the comparison circuit 13 is equal to the count number when the down counter 8 counts down by 5, and the reference value of the comparison circuit 14 is equal to the count number when the down counter 8 counts down by 5. value is,
It is set equal to the count number when the up counter 9 counts up by 2.

Therefore, when the first pulse b (time ts) from the sensor circuit 10 occurs, the output signal of the comparison circuit 12 becomes "1" and the output signal of the comparison circuits 13 and 14 becomes "0". The output signal of the comparator circuit 12 is inverted by the inverter 7 to become 100''', and is supplied to the NOR circuit 18 together with the output 4It% of the comparator circuits 13 and 14. On the other hand, the pulse b of @Qll is also supplied to the NOR circuit 18. , As a result, time t,
At this time, the level of the output value @f of the NOR circuit 18 becomes 1''.Then, the -l'' pulse f from the NOR circuit 18 passes through the OR circuit 19, and the third pulse of the output pulse j (
It is supplied to the right shift terminal sR of the 4-bit shift circuit 20 as time 1+). However, the 4-bit shift circuit 20 performs a right shift by 1 bit, and the output becomes "O;'
0, 1, l” and the stepping motor 2
4 is rotationally driven in the BD phase (between t1 and tq in FIG. 6).

Therefore, when the stepping motor 24 further rotates and the sensor circuit 10 generates the next pulse b at time t2,
The up counter 9 has counted up by 2, so compare this count number! When the reference values of 814 match, the output signal C of the comparison circuit 14 becomes 1". However,
The level of the output signal f of the NOR circuit 18 does not change even if the pulse b is supplied and remains at "O'. Therefore, the 4-bit shift circuit 20 does not shift, and the stepping motor 24 remains unchanged even after time t1. is rotationally driven in the BD phase (time 11 in Figure 6).

The output signal C of the comparison circuit 14 is supplied to the timer 16. The timer 16 starts operating at the rising edge of the output signal C, and generates a pulse h at time t, when a predetermined period of time has elapsed from time t.
occurs. The pulse h is supplied to the OR circuit 19, and is supplied to the right shift terminal 8R of the 4-bit shift circuit 20 as the fourth pulse (time tq) of the output pulse j.
The bit shift circuit 20 performs a right shift and the output is “1”.
．． o, o.

1'' and rotates the stepping motor 24 in the AD phase (#16 between FIG. 1q and 1).

Next, at time t, when the sensor circuit 1810 generates the next pulse b, the reference value and the supplied count number no longer match in the comparison circuit 14, and the same is true for comparison 1g1j812.13. Therefore, the 4-bit shift circuit 1820 performs a right shift, and the output is "1, 1".
, 0.0°, and the 1 stepping motor 24 is synchronously driven in the 〇 phase (6th @ between ts and ts), at time t
4, the 4-bit shift circuit performs a right shift and the output becomes 0, 1, 1, 0'', and the stepping motor 24 is rotationally driven in the BC phase (see Fig. 6, 1).
．． ~t, between).

At time 11, the count number of the down counter 8 and the reference value of the comparison circuit 13 match, and the output signal d of the comparison circuit 13 becomes "1". Therefore, as in the case of time t, no input pulse is supplied to the right shift terminal 8R of the 4-bit shift circuit 20 at time t. However, the output value @d of the comparison circuit 13 is supplied as a pulse to the left shift terminal 8L of the 4-bit shift circuit 20, and the 4-bit shift circuit 20 performs a 1-bit left shift. As a result, the output becomes "1, 1, 0.0", the stepping motor 24 is driven in the AC phase, and a reverse torque is generated (between t and tr in FIG. 6).

Further, the output signal d of the comparison circuit 13 is supplied to the timer 15. The timer 15 starts operating at the rising edge (leading edge) of the output signal d, and at time 1. A pulse i is generated at time tr after a predetermined time has elapsed since then. The pulse i is supplied to the OR circuit 19, and is supplied to the right shift terminal SR of the 4-bit shift circuit 20 as the seventh pulse (time tr) of the output pulse j. Therefore, the 4-bit shift cycle Wa2o performs a 1-bit right shift, and the output is "+1, I, 1,
Oo, and the stepping motor 24 is driven again in the BC phase.

Next, at time ts, when the sensor 11 detects the hold position, the output signal of the sensor circuit 10 rises and the down counter 8 is further counted down by l, but the count number at this time is equal to the reference value of the comparison circuit 120. Therefore, the output signal of the comparison circuit 12 becomes "θ". This output signal is supplied from the output terminal 25 to a circuit not shown,
Stepping motor 2 stops generating operation of drive current.
Stop 4.

Although a specific example of a drive current generating circuit has been shown above, it is not limited to such a generating circuit, but other circuits having similar functions are also possible, and some parts may be replaced with a four-microphone, four-hunter computer. It is clear that it can be done.

Although the above embodiment has been explained using one printer as an example, the present invention is not limited to this. The driving source is a stepping motor, and the rotation of the stepping motor can cut a moving object by pulling a wire. It is clear that it can be applied to any device adapted to move electric distances.

As explained above, according to the present invention, the stepping motor can be started rapidly, and a large torque can be generated during the period when wire tension is applied until the moving object starts moving. is capable of performing a stable rotation operation without reversing the direction of rotation, and is capable of accurately and quickly moving a moving object by a predetermined distance,
It is possible to provide a method for driving a stepping motor with excellent functions not found in the prior art.

[Brief explanation of drawings]

Figures 1 (α), (b), and (C) are timing charts showing an example of a conventional stepping motor driving method;
Figures (α) and (b) are timing charts showing other examples of the conventional stepping motor driving method, Figure 3 is a timing chart showing still another example of the conventional stepping motor driving method, and Figure 4 is a timing chart showing another example of the conventional stepping motor driving method. A timing chart showing still another example of the driving force method for the motor of the carriage moving device of the printer, Figure 6 ((1), (b), and (C) shows one implementation of the stepping Tanabata driving method according to the present invention. A timing chart showing an example, FIG. 7 is a block diagram showing a specific example of the drive current generation circuit for each phase shown in #16 (b), 1
Figure s8 is a timing chart for explaining the operation of Figure #I7. Dormitory I Figure Figure 2 Figure 3 Closed Figure 4 Figure 5 Figure 60 Hou 7 Ward Procedural Amendment (Method) December 6, 1980 Kazuo Wakasugi, Commissioner of the Japan Patent Office 1, Indication of the Case 1988 Patent Application No. 159254 2, Title of the invention Stepping motor driving method 3, Relationship with the case of the person making the amendment Applicant 6, Subject of the amendment (1) r (a) l (b) on page 11, line 5 of the specification )
? (C) Delete the description of J. (2) Page 25, line 1 of the specification (7) r (a)
r (b) J ノ812 is deleted. (3) r(a), (b) on page 25, line 6 of the specification
), (C) J will be deleted.

Claims (2)

[Claims] (1) In a stepping motor driving method in which two phases are simultaneously excited and a moving object is moved a predetermined distance via a wire, the energization period of each phase is sequentially switched using a sensor pulse generated at the hold position when two phases are energized. and a starting cylinder of the stepping motor switches the energization period of a predetermined phase so as to generate a predetermined torque in the stepping motor against increasing wire tension during the movable body stop period until the movable body starts moving. . A method for driving a stepping motor, characterized in that the operation of the stepping motor during the period when the moving object is stopped can be stabilized. (2) In claim (1), the switching of the energization period of the predetermined phase includes two lK switchings that generate torque that increases sequentially after starting the stepping motor, and the first of the sensor pulses. Switching to the other two phases that generate sequentially increasing torque at the time of generation of the pulse, and a point at which a predetermined period of time has passed from the time of generation of the first pulse to the time of generation of the second pulse of the sensor pulse. A method for driving a stepping motor, characterized in that a sufficiently large torque can be generated for a maximum wire tension at the time when the moving body starts moving during a period a11L.