JPS61203898A - Pulse motor drive device - Google Patents

Abstract

PURPOSE:To smoothly stop a pulse motor which is driven at a high speed in a short time by storing an interval time at an accelerating time, and controlling an exciting phase switching timing at a decelerating time in response to the interval time. CONSTITUTION:The interval time of switching the exciting phase switching when a pulse motor 15 is accelerated is measured by encoder means 22, 23 of the motor 15, and stored in a RAM31. Since the time amount stored in the RAM31 is data for obtaining the maximum acceleration by including factors such as a drive circuit 14, a pulse motor 15, friction and inertia of a drive system connected, the row of the time amount is reversely used to decide the drive interval at the decelerating time to decelerate the motor smoothly, the motor is shifted to the stop state without difficulty in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a pulse motor drive device, and more particularly to a pulse motor drive device that controls acceleration and deceleration of a pulse motor.

[Prior art] Pulse motors rotate by a predetermined rotation angle by pulse drive, so they are highly compatible with digital technology, and are widely used in computer-applied equipment such as printers because they enable highly accurate position control. . However, there are several problems when decelerating or stopping a pulse motor that is being driven at high speed.

FIG. 1 shows an example of a conventional pulse motor drive circuit. In FIG. For example,
When decelerating the pulse motor 15, data is stored one byte at a time so that the count decreases each time one address is increased.

The data output from the largest address of ROMII (where the smallest count amount is stored) is set in the timer 12, and the timer counts the set count value based on a clock pulse (not shown) and starts counting. When this is completed, a pulse is given to the excitation phase switching circuit 13 to advance the pulse motor 15 by one step via the drive circuit 14.

On the other hand, when the timer 12 counts up, the ROMI
The address is decremented from I, and the next data, that is, a count amount larger than the previous data, is output to the timer 12.
is set to

By repeating the above operations, the interval at which the pulse motor 15 is advanced by one step is gradually increased, and the pulse motor 15 is decelerated. Then, when a desired interval is reached, that is, when the pulse motor 15 reaches the desired rotation speed, the count value set in the timer 12 is set to a constant value, and the pulse motor 15 is continuously rotated at a constant speed. . To stop, repeat the above operation, and when the speed drops to a predetermined speed, start the timer 12.
Stop setting data to.

However, in the above-described system, depending on the data stored in the ROM 11, the pulse motor 15 may not rotate smoothly, or the pulse motor 15 may require a time longer than the possible deceleration time to decelerate. In order to perform optimal deceleration drive, strictly speaking, the data to be stored in the ROM must be determined by taking into consideration the characteristics of the pulse motor including the drive circuit, and the actual load and inertial load of the connected drive system. However, since these characteristics vary depending on product variations and usage time, it is extremely difficult to always obtain desired high-speed rotation characteristics using conventional methods.

[Purpose] The present invention was made in view of the above problems, and even when various conditions such as the load on the drive system are not strictly known,
An object of the present invention is to provide a pulse motor drive device that can smoothly stop a pulse motor that is being driven at high speed in a short time.

[Structure of the Invention] In order to achieve the above object, the present invention includes a pulse motor and a means for measuring the interval time of excitation phase switching during acceleration of the pulse motor using an encoding means provided on the drive shaft of the pulse motor. , storage means for sequentially storing measured interval times during acceleration, and an interval time stored in the storage means during the deceleration period, which is reversely read out and inputted to determine the excitation phase switching timing of the pulse motor during deceleration. A configuration was adopted that included a time control means.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

FIG. 2 is a block diagram showing an example of the configuration of a pulse motor drive device according to the present invention. Reference numeral 21 in Figure 2
The one indicated by is an OR gate, and a starting pulse pt is inputted to one of its inputs via a signal line 28. An excitation phase switching circuit 13 is connected to the output of the OR game) 21. The excitation phase switching circuit 13 is a known circuit that switches the excitation phase of the pulse motor 15 via the drive circuit 14 every time a pulse is input.

When the pulse motor 15 is driven with two-phase excitation, two phases of adjacent pulse motors 15 are driven simultaneously, and when excitation is switched, the phases that are driven simultaneously are overlapped and changed. For example, when phases 1 to 4 are arranged next to each other, if phase 3.4 is driven at a certain point, then phase 4.4 is driven by switching. Phase 1 is driven and phase 3 current is cut off.

The drive circuit 14 is composed of switching transistors connected to each phase of the pulse motor 15, and converts the logic level signal of the excitation phase switching circuit 13 to a level sufficient to drive the pulse motor 15.

The drive shaft of the pulse motor 15 is connected to a printer carriage, platen, etc. (not shown) via a speed reducer or the like. Further, as shown in the figure, an encode plate 22 having slits cut at equal angles around the circumference of a light shielding material is attached to the drive shaft. A photointerrupter 23 is arranged near the encode plate 22 so as to sandwich the encode plate 22 therebetween. The photointerrupter 23 is a known element consisting of a light emitting diode, a photosensor, etc., and outputs a pulse when the slit of the encoder plate 22 through which light passes passes.

The output of the photointerrupter 23 is input to a waveform shaping circuit 29 using a Schmitt trigger, etc.
The 9 shaped output pulses are connected to the contacts 33 of the switch 27, the input terminal 35 of the CPU 20, and the reset terminal of the counter 30 via the signal line 34.

The switch 27 switches the connection of the other input terminal of the OR gate 21 between the contacts 38 and 33. An input terminal 36 of the CPU 20 is connected to the contact 38 .

A CPU 20 composed of a microcomputer etc. is connected to a RAM connected by a data bus B for control described later.
(random access memory) 31, a counter 30, and a timer 36.

The CPU 20 sets the counter 30 via the signal line 32 and inputs the output of the timer 36 from the terminal 36.

Next, the operation of the above configuration will be explained.

In the above configuration, to accelerate the pulse motor 15 from a stopped state, switch the switch 27 to the contact 33 side, and
U20 outputs a starting pulse Pt from the signal line 28 to the OR gate 21 and also starts the counter 30 via the signal line 32.

When a starting pulse Pt is input to one terminal of the OR gate 21, the excitation phase switching circuit 13 synchronizes with this and first performs the first excitation phase switching, thereby reducing the slight signal delay time that the drive circuit 14 itself has. After the moving time of the movable element of the pulse motor 15, three and three of the encoder plate 22 enter the position of the photointerrupter 23, and the signal is shaped by the waveform shaping circuit 29 and sent to the switch 27.
via the OR gate 21, the input terminal 35 of the CPU 20,
and is input to the reset terminal of the counter 30.

A pulse input to the OR gate 21 advances the pulse motor 15 by one step again in the same manner as described above. C
The PU20 operates the pulse motor 1 by the pulse of the input terminal 35.
5 is detected, and in response to this, the counter 3
A count amount of 0 is stored in a predetermined address of the RAM 31. Then, the counter 30 is activated again via the signal line 32.

The pulse first applied to the OR game 21 via the switch 27 advances the pulse motor 15 by one step via the excitation phase switching circuit 13 and the drive circuit 14 in the same manner as described above, and is detected by the photointerrupter 23 at that time. This pulse stops the counter 30, and the counted amount at that time is stored in the next address of the RAM 31.

By repeating the above operations, the pulse motor 15 is accelerated.

Here, FIGS. 3A and 3B show the starting pulse Pt and the pulses obtained from the waveform shaping circuit 29, respectively. In FIG. It shows the amount of time that is stored in the RAM 30. As shown in FIG. 4, the time amount 11 is placed at a predetermined address X in the RAM 30, t2 is placed at a predetermined address X+1, and so on.
and tn is stored at address X + n -1.

When the amount of time tn reaches the minimum possible value, the CPU 20
Stop writing to M30 and perform constant speed operation.

According to the above-described acceleration drive, even if the inertial load and overload vary, the excitation phase can be switched as quickly as possible according to the change, and the pulse motor 15 can be driven at the maximum possible rotation speed. can. In addition, for this control, information including the delay time of the drive circuit 14 is transmitted to the encoder board 2.
2. Feedback is provided from the encoder of the photo interrupter 23. Therefore, in the conventional control using ROM shown in FIG. 1, data must be created taking various complicated factors into consideration in order to ensure accuracy, whereas in this embodiment, such troublesome There is no acceleration, and acceleration can be performed at the maximum possible acceleration immediately after startup, and the speed of
Alternatively, driving can be performed at the highest possible speed.

Next, control when decelerating with the above configuration will be explained.

When decelerating, the switch 27 is switched to the contact 38 side. And the address of RAM30 X + n -1
The count data tn stored in is read out and stored in the timer 36 via data bus B.

The timer 36 counts the set tn according to a clock (not shown), and when this counting is completed, a pulse is given to the OR gate 21 via the switch 27, and the pulse motor is supplied via the excitation phase switching circuit 13 and the drive circuit 14. 15 is driven one step. At this time, the CPU 20 uses the RAM 3
Data tn is read from an address that is 1 smaller than the address X + n -1 of 0, and is set in the timer 36. When the timer finishes counting, the pulse motor 15 is driven one step via the excitation phase switching circuit 13 and the drive circuit 14 in the same manner as described above.

By sequentially repeating the above steps, the step drive interval of the pulse motor 15 is determined as shown in Fig. 3 (B) c7) t n
, tn-1, tn-2-t3, t2, and tl, the pulse motor 15 can be driven at a reduced speed.

Moreover, the amount of time stored in the RAM 30 is the same as the amount of time stored in the drive circuit 14. Since this data is the maximum acceleration obtained after including factors such as the force and inertia of the pulse motor 15 and the connected drive system, the drive interval during deceleration can be calculated using this time series in reverse. By determining this, the pulse motor can be smoothly decelerated, and the pulse motor rotating at high speed can be smoothly brought to a stop state in a short period of time. Therefore, even if various conditions such as the load on the drive system are not precisely known, there is no need to store these conditions in the storage means, and even if these conditions change, they can be corrected from the control during acceleration. As a result, desired deceleration and stopping characteristics can be obtained.

In the above, the two-phase excitation force type was shown as the excitation method, but l.
The present invention can also be implemented in one of various drive systems such as a two-phase excitation force type.

[Effects] As is clear from the above description, according to the present invention, a pulse motor and a means for measuring the interval time of excitation phase switching during acceleration of the pulse motor using an encoding means provided on the drive shaft of the pulse motor. and storage means for sequentially storing the measured interval times during acceleration; and the interval times stored in the storage means during the deceleration period are reversely read out and inputted to determine excitation phase switching timing of the pulse motor during deceleration. To smoothly decelerate a pulse motor according to the characteristics of a drive circuit and the characteristics of a drive system, and to smoothly shift a pulse motor rotating at a high speed to a stopped state in a short time, using a configuration provided with a timing means for controlling the speed. It is possible to provide an excellent pulse motor drive device that can.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a conventional pulse motor drive device, FIG. 2 is an explanatory diagram showing the configuration of a pulse motor drive device according to the present invention, and FIG. A waveform diagram showing the timing of the start signal, Figure 3 (B) is a waveform diagram showing the output of the waveform shaping circuit, and Figure 4 is a waveform diagram showing the output of the waveform shaping circuit.
It is an explanatory diagram showing a data storage state of AM. 13... Excitation phase switching circuit 14... Drive circuit 15... Pulse motor 20
...CPU 21...Orgate 22...
・Encoding board 23...Photo interrupter

Claims (1)

[Claims] a pulse motor, a means for measuring an interval time of excitation phase switching during acceleration of the pulse motor using an encoding means provided on a drive shaft of the pulse motor, and a storage means for sequentially storing the measured interval time during acceleration; A pulse motor drive device comprising a timer for controlling excitation phase switching timing of the pulse motor during deceleration by reading out and inputting the interval time stored in the storage means in reverse during the deceleration period.