JPS61161996A - Method of controlling stepping motor - Google Patents

Abstract

PURPOSE:To start a stepping motor in the state that the torque of the motor is pull-out torque by applying a pulse of reverse rotation immediately after a normal direction pulse to reversely rotate in the amount of fluctuation (play). CONSTITUTION:A drive pulse applied to a stepping motor is formed to be shown by a timing chart as shown. Here, F is forward feeding normal rotating direction, R is reverse direction, PF is normal rotating direction pulse, and PF' is reversely rotating pulse. Thus, reverse rotation pulse (PF') is applied immediately before or after the normal direction pulse (PF) applied to the motor to reversely rotate in the amount of fluctuation (play), thereby presenting the accumulated play at a starting load side at next normal rotation time to start with substantially no load.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of controlling a stepping motor, and particularly to a control method for reducing the starting load thereof.

[Conventional technology]

Stepping motors (step motors, pulse motors, or PF motors, hereinafter abbreviated as PF motors) have been widely used in recent years, especially in electronic devices and the like.

As an example, FIG. 2 is a mechanical explanatory diagram of a tractor foot device for feeding continuous printing paper into one latin of a line printer.

PT is the platen, P is the continuous printing paper, and T is the paper P.
A tractor with a groove that engages with the perforation 1 on the side of the tractor, M is a PF for driving the tractor.
In the motor, this power is transferred to the drive pinion 1. Each intermediate gear 2
, 3, 4.5'. 6 is a tension roller.

In the case of the above-mentioned tractor feed method, in the case of forward feeding of continuous paper in normal printing operation, the conventional PF motor M sends the pulse PF1 in the forward rotational direction of the motor as shown in the timing chart No. 31. It was fed by moving it forward.

Further, FIG. 4 shows an explanatory diagram of a ribbon feed mechanism for transporting an ink ribbon in a printer as another application example of the PF motor. I(, B are endless ink ribbons wound around the suguru 10 and stored in the ribbon cassette 12.

The ribbon L (, B is driven through a PF motor M, a drive pinion 13° driven gear 14, and a feed roller 15. To transport the ribbon RB in the forward direction F, conventional P
The F motor M determines the number of steps according to the ribbon feeding teeth, and feeds the ribbon by sending a pulse PF-4 in the forward rotational direction F of the motor, as in FIG. 3 above. PT indicates platen.

[Problem that the invention seeks to solve]

However, in the case of the two conventional application examples of the PF motor shown in FIG. 2 and FIG. In the case of the first example (Fig. 2), between the ribbon and B, there is a There are looseness etc.
In the case of the second example (Fig. 4), the meshing gear 13.1
There is always some backlash (play) in the mechanical attachment of the pack run between the four parts, the feed roller 14, the ribbon R, etc.

Therefore, in the case of the first example (Fig. 2), the paper wound around the platen is often manually pulled out in the forward or reverse direction while printing is stopped. A load in the opposite direction (bavku tension) acts, and the accumulated play of the above-mentioned bala clarine and backlash is biased in either the forward or reverse direction, and the load is applied to the next time the motor is started. Related.

Also, in the case of the second example (Fig. 4), when the motor M stops, the stopped state of the gears 13, 14 and the ribbon L (, B) is not constant, and depends entirely on the state at that time. Similarly, it is related to the load at the next start-up of the motor.In both cases, the load at the next start-up of the PilI motor M faces a large static resistance such as paper or ribbon without the intervening play. This is due to the difference in whether the

However, on the other hand, as is well known, the PF motor M is
It has the torque characteristics shown in a) and (b).

(a) The figure shows the relationship between %9 pS (pulse number 7 seconds), pull-in torque (maximum torque before startup) T91, and pull-out torque (maximum torque during operation) TI) When the ppS of is the A value, T po ” s T9s ”, respectively.

Further, FIG. 12(b) shows a time-torque characteristic indicating the motor output when the above-mentioned motor is driven at Ap9S° C., and the rise time Δt is a time corresponding to 2 to 4 pulses at most.

Here, in the case of the first conventional example (Fig. 2), Pi
111 When the motor is started, the paper load is back ten 7iI and the aforementioned cumulative play in the transmission system does not exist, so the motor output must be started with a low torque n that is a large starting load. , when selecting the PF motor M4, it is necessary to select a high output motor that has a pull-in torque capacity equivalent to tsm. This also applies to the case of the second conventional example (Fig. 4).
The same is true.

However, recent electronic devices are required to be more and more compact and lightweight, and the present invention was made in view of the above-mentioned problems. By configuring the motor so that the pull-in torque is sufficient at the moment of startup, starting with virtually no load, and then bearing the load torque with the pull-out torque, it is possible to use a small-output PF motor. The aim is to contribute to making equipment smaller, lighter, and lower in cost.

[Means for solving problems]

Therefore, in the present invention, in order to start the PF motor with virtually no load, a pulse in the reverse direction is applied immediately before or immediately after the pulse in the forward direction given to the PF motor to cause the PF motor to reverse by the amount of backlash (play). The above-mentioned cumulative play is made to exist on the starting load side at the time of the next normal rotation, so that the CPF motor can be started with the torque of the CPF motor at the pull-out torque.

〔Example〕

The present invention will be explained below based on examples. Figure 1 (a
) and (b) show two examples of timing charts of control pulses of the PF' motor M according to the present invention. F represents a forward rotation direction for forward feeding, R represents a reverse direction, PF represents a forward rotation direction pulse, and PF' represents a reverse direction pulse. (a) Figure &XPi1v immediately before PF', and (b) Figure is P 1
It is added immediately after 1''g PF, and the shaded area between each combination pulse indicates the operation time of printing, etc.

By controlling the PF' motor as described above, the PF
The motor can be started with pull-out torque and sufficient torque margin.

As mentioned above in FIG. 5(b), the rise time Δt at startup is at most 2 to 4 pulses, so if A=1
Assuming 50pps, Δt=1/150×(2-4):
It is a short time of 0.013 to 0.027'.

In this case, if there is a cumulative play of 4 pulses in the paper or ribbon feeding transmission system, in the case of printer paper, normally 1 pulse is 1/96 x 25.4 ■ x 4 = 1.1 -
Therefore, it is possible to reversely rotate by this accumulated backlash and therefore rotate in the forward direction.

In other words, while the PF motor M rotates through this play, the output torque shifts from the pull-in torque to the pull-out torque range, so when the paper or ribbon is actually driven, it is driven with a high pull-out torque. Become. 6th
Figures (a) and (b) are timing charts of the motor torque and load (driving torque for paper, etc.) at this time.

Although the above explanation has mainly focused on the case of the conventional example (FIG. 2), the second example (No. 4 C) is also the same in principle, and the same effect can be obtained.

Furthermore, it is obvious that the cumulative play due to reverse rotation may be provided immediately after normal rotation as shown in FIG. 1(b).

[Results of invention]

As explained above, according to the stepping motor control method of the present invention, since the starting load of the device is configured to be performed by pull-out torque, it is necessary to select a motor with a relatively low output compared to the conventional method for use in the device. This makes it possible to contribute to making equipment smaller, lighter, and lower in cost.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are PFs according to the present invention, respectively.
Two examples of motor control pulse timing charts. Fig. 2 is an explanatory diagram of the paper tractor feed mechanism of a conventional line printer. Fig. 3 is a conventional motor control pulse timing chart. Fig. 4 is an illustration of a conventional printer's ink feed mechanism. An explanatory diagram of the ribbon feed mechanism, FIG. 5(a). Figures (a) and (b) are torque timing charts of the stepping motor and load of the present invention, respectively.M...Stepping motor PF... Forward rotation pulse PF'...Reverse rotation pulse Tp,...Pull-in torque Tpo...Pull-out torque P...Continuous printing paper B...Ink ribbon

Claims (1)

[Claims] In a stepping motor that drives a device in which there is play in the motion transmission system of a load, a reverse pulse is applied immediately before or after each forward rotation pulse applied to the stepping motor to reverse the stepping motor by the amount of play. A method for controlling a stepping motor, characterized in that the stepper motor can be started by a pull-out torque of the motor when the next normal rotation is started.