JPH02266895A - Method of driving stepping motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for driving a stepping motor, and particularly to a method for quickly eliminating speed fluctuations when entering a constant speed region.

[Problem to be Solved by the Invention] By the way, in such a conventional drive system, as shown by the dotted line in FIG. 4, when FIG. 4 is viewed as a speed-time diagram, immediately after transition from the acceleration region to the constant speed region In this case, a damping phenomenon occurs due to the inertia of the exercise load system, the structure of the stepping motor, its excitation method, etc.

For example, when used as a drive source for moving a carrier in a printing device, if the speed instability due to the damping phenomenon is long, a problem arises in that clear prescribed printing cannot be performed during that period.

On the other hand, by making the inclination angle of the acceleration line gentler, the speed fluctuation (unstable) time can be shortened to some extent. However, in this case, the acceleration (deceleration) time becomes extremely long, making it impractical.

On the other hand, it has been proposed to quickly eliminate the damping phenomenon using a mechanical damper, but this countermeasure causes a large load during acceleration (deceleration), which is contrary to the goal of high speed and miniaturization. Furthermore, forming the motor so that it acts only immediately after entering the constant speed region requires a complicated structure, which is disadvantageous in terms of space and cost. Moreover, it is not practical because it has to be adjusted every time the load etc. changes.

The present invention was devised based on these circumstances, and its purpose is to provide a stepping motor drive system that can easily and appropriately reduce the damping phenomenon and achieve constant speed rotation at an early stage. It is in.

[Means for Solving the Problems] The present invention is based on the electrical characteristics of a transition from a drive signal frequency in an acceleration region to a drive signal frequency in a constant speed region, and of a motion load system that is continuously energized in an acceleration region. Focusing on the lack of alignment of mechanical properties and their arbitrariness, we created a motion at the end of the acceleration region in advance so that the magnetic force based on the drive signal of the first outlet in the constant speed region does not act as a pullback force on the rotor. The above problem is solved by actively reducing and adjusting the acceleration energy of the load system.

In other words, the speed is adjusted so as to draw a trapezoidal frequency-time diagram, which has an acceleration region where the drive signal frequency increases with time, a constant speed region where the drive signal frequency is constant, and a deceleration region where the drive signal frequency decreases with time. In the method of driving a stepping motor to be controlled, before transition to the constant speed region, a drive signal of a constant frequency that deviates from an acceleration line defining the acceleration region and is lower than the drive signal frequency of the constant speed region is continuously applied. This feature is characterized in that the damping is adjusted by adding only a predetermined period of time.

[Function] In the present invention, immediately before entering the constant speed region, the acceleration line is set at a frequency that makes it difficult to continuously maintain the acceleration line along its extension, and is lower and constant than the drive signal frequency of the constant speed region. A frequency drive signal is continuously applied for a predetermined period of time,
Apply a brake to the exercise load system. Therefore, since the energy possessed by the motion load system is small when the vehicle enters the constant speed region, the damping phenomenon can be significantly reduced.

[Example〕 Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, a stepping motor is used as a source of reciprocating motion for a carrier (printing device) that holds a print head.
The stepping motor is a four-phase type, and is driven and controlled by a 1-2 phase excitation force type. FIG. 3 is a schematic diagram of the driving device, in which 1 is the main body of the printing device, 2 is the stepping motor, 3 is a drive circuit and 5
is the control unit of the printing device.

The control unit 5 has a CPU 7 connected to a bus 6, RO
M8. Clock circuit 9. It is formed to include an interface 10 and the like.

The frequency-time diagram is written in the ROM 8 in advance.

Specifically, as shown in FIG. 1, a drive signal (more specifically, an excitation switching signal) is outputted to the drive circuit 3 via the CPU 7 and the interface 10 at approximately 4800 pps, that is, every 210 μs, at a drive signal frequency of 2 in the constant speed region. Write as time interval data as shown below.

On the other hand, the frequency f1 in the acceleration region is a function of time t [in principle, f1=f (t)], and in this example,
The time interval in this example is written as a linear function so that the acceleration line is a straight line, but does not limit the accuracy of shortening the interval every 2 μs, for example, 246 μs then 244 μs. 400μs (2500p
pS equivalent) to 210 μs (equivalent to about 4800 pps).

Here, in the present invention, a damping adjustment region is provided before the transition from the acceleration region to the constant speed region.

This damping adjustment area is f1=f(t) as described above.
A frequency that deviates from the acceleration line specified in
This is a region in which three drive signals are continuously applied for a predetermined time (setting changeable) at a constant frequency lower than one in the constant speed region. In this embodiment, as seen in FIG. 1, the frequency f2 is lower and constant than the frequency f1.
(240 μs).

Therefore, the frequency-time diagram becomes as shown in FIG.

Therefore, according to this embodiment, as shown by the dotted line when FIG. 2 is viewed as a speed-time diagram, speed control without speed fluctuations is achieved.9For example, f1=f (t) From 400 μs to 210 μs based on, f2=const,
Based on <210. Compared to the conventional method that immediately shifts to czs, the instability (fluctuation time) until the speed falls within the allowable range can be shortened to approximately 1/10 to 1/10.

In the above example, 20 low frequency drive signals were applied continuously during the transition from the acceleration region to the constant speed region.
The frequency and number can be selected arbitrarily.

[Effects of the Invention] As is clear from the above explanation, the present invention is a drive method that continuously applies a low frequency drive signal that deviates from the acceleration line for a predetermined time before transitioning from the acceleration region to the constant speed region. Therefore, the speed instability and fluctuation time due to the damping phenomenon can be dramatically shortened or eliminated. Further, it has the advantage of being widely adaptable and capable of being quickly and easily adjusted in response to the exercise load system.

Figure 3

[Brief explanation of drawings]

FIG. 1 is a timing chart showing an embodiment of the present invention;
FIG. 2 is a frequency-time diagram, FIG. 3 is a schematic diagram of the driving device, and FIG. 4 is a frequency-time diagram according to the conventional driving method. 2...Stepping motor, 3...Drive circuit, 8...ROM, 10...Interface.

Claims (1)

[Claims] (1) Draw a trapezoidal frequency-time diagram with an acceleration region where the drive signal frequency increases with time, a constant speed region where the drive signal frequency is constant, and a deceleration region where the drive signal frequency decreases with time. In a method for driving a stepping motor that controls speed, before transition to the constant speed region, a drive signal of a constant frequency that deviates from an acceleration line defining the acceleration region and is lower than the drive signal frequency of the constant speed region is continuously applied. A method for driving a stepping motor, characterized in that damping is adjusted by adding damping for a predetermined period of time.