JPH01198300A - Driver for step motor - Google Patents

Abstract

PURPOSE:To drive a step motor with high speed without employing a complex and expensive power source circuit, by changing input power when the step motor is stopped, rotated with low speed and rotated with high speed. CONSTITUTION:A power switching circuit 3 switches power to be fed to a step motor 1 in two stages. A memory 5 stores data series for controlling a driver 2 through a controller 4 and data series for controlling the power switching circuit 3. When the step motor is stopped, low power state is brought out while when the step motor 1 is rotated with low speed, high power state is brought out for a predetermined time every time when the step motor 1 is rotated by one step thus producing torque. Thereafter, low power state is brought out to suppress power consumption of the step motor 1, and high power state is brought out when the step motor 1 is rotated with high speed.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention provides a step motor that realizes high-speed drive with low power;
This relates to a drive device.

In recent years, step motors have been widely used in serial printers and electronic typewriters due to their ease of construction and control. Efforts have been made.

An example of a conventional step motor drive device will be described below with reference to the drawings.

FIG. 4 shows a block diagram of a conventional step motor drive device. In FIG. 4, 1 is a step motor, 2 is a drive circuit that drives the step motor 1, 4 is a control device (microcomputer) that controls the drive circuit 2, and 6 is a device for the control device 4 to control the 5 drive circuit 2. A storage device that stores data strings.

The operation of the step motor drive device which has been increased by +1IIX as described above will be explained below.

First, the drive circuit 2 supplies current to each winding of the step motor 1 in response to a signal from the control device 4, and the step motor 1 rotates by one step angle. A data string is stored, and by supplying a signal from the control device 4 to the drive circuit 2 at a timing based on the numerical data string, the step motor 1 can be driven to rotate smoothly. Table 1 shows a part of the above numerical data string.

Table 1 A case will now be described in which the control device 4 rotates the step motor 1 by a predetermined number of pulses, for example 12 pulses.

The control device 4 gives a signal to the drive circuit 2 to rotate the step motor 1 by one step angle, and after a time period of 6.3 milliJ seconds corresponding to data T1 in Table 1 has elapsed, gives a signal to the drive circuit 2 to rotate the step motor 1 by one step. Motor 1 is rotated by one step angle. That is, as shown in FIG. 5, the control device 4 starts at T1, and then sequentially: T2. T3+'r4・・・・・・
A signal is supplied to the drive circuit 2 at the timing of , and the stepping motor 1 is rotated and accelerated. When the control device 4 completes one drive of the sixth pulse, which is a predetermined number of pulses, which is one-half of 12 pulses, the control device 4 then controls the drive circuit using the numerical data in Table 1 in reverse order, as shown in FIG. 2, the step motor 1 is rotated, decelerated, and stopped after the final pulse movement.

In the above-mentioned step motor drive device, by setting the numerical data shown in Table 1 to theoretical data calculated based on any appropriate function, the step motor 1 is accelerated and decelerated extremely smoothly, and extremely easy to move. Hard to cause irritation.

Problems to be Solved by the Invention However, with the above configuration, in order to increase the speed, it is necessary to increase the power supplied to the step motor to increase the torque, but this requires complicated and expensive steps. There were problems in that a power supply circuit was required, and the step motor was also expensive and required a large current capacity. Additionally, if a low-cost step motor with a small current capacity is used to ensure torque during high-speed rotation, an excessive current exceeding the current capacity will flow to the step motor during low-speed rotation or when the step motor is stopped, resulting in damage to the step motor. It had all the problems.

In view of the above-mentioned problems, the present invention provides an expensive step motor with a large current capacity and a step motor drive device ft that can be driven at high speed without using a complicated and expensive power supply circuit.

Means for Solving the Problems In order to achieve this object, a step motor and a driving device of the present invention provide a first data string representing a pulse interval of a drive pulse applied to a single-movement circuit that drives a step motor, and The driving circuit and the power switching circuit are controlled by a second data string representing the timing of a signal given to a power switching circuit capable of switching the power supplied to the motor in two or more stages, and the first and second data strings. It has a configuration that

Operation With this configuration, when the step motor is stopped or rotates at low speed, the power switching circuit is controlled so that the step motor is in a low power state when it is stopped, and when it is rotating at low speed, it is in a high power state and torque is applied for a predetermined period of time every time it rotates one step. Later, by setting the low power state to a low power state, the power consumed by the step motor is kept low, and by constantly setting it to a high power state during high speed rotation, the power consumed is evened out from a stopped state to low speed rotation and even high speed rotation. This makes it possible to simplify the power supply circuit, use an inexpensive step motor with a small current capacity, and achieve high speed while reducing costs.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of a step motor and a driving device in one embodiment of the present invention. In FIG. 1, 1 is a step motor, 2 is a drive circuit that drives the step motor 1, and 3 is a drive circuit that supplies power to the step motor 1.
4 is a control device for controlling the drive circuit 2 and the power switching circuit 3; 5 is a data string for the control device 4 to control the drive circuit 2 and data for controlling the power switching circuit 3; A storage device that stores columns.

The operation of the step motor 1 drive device of this embodiment configured as described above will be described below.

First, in the storage device 5, as in the conventional example, a data string 5a based on an arbitrary function indicating the timing of a signal to be given to the drive circuit 2 is stored in advance. l ”a2 +...), the control device 4 gives a signal to the drive circuit 2, and the drive circuit 2 uses the signal to supply current to each excitation phase of the step motor 1 to turn the step motor 1 into one. The stepper motor 1 is rotated by the step angle. At this time, the current waveform supplied to the stepper motor 1 becomes as shown in FIG. 2a.

The storage device 6 also stores a data string 5b based on an arbitrary function, which indicates the timing of switching the power of the power switching circuit 3. As shown in FIG. Data string 5 for controlling the drive circuit 2
The high power state is entered at the timing based on 1L, and the timing based on the data string 6b (Tb1+Tb21...
) is controlled by the control device 4 to enter a low power state. Too indicates the time to enter the high power state at the time of stopping. FIG. 2 shows the output waveform of the power switching circuit 3, and FIG. 2C shows the waveform of the current supplied to the step motor 1 when the power is switched. A case will now be described in which the control device 4 performs the Mi-th step angle rotation. First, the control device 4 gives a signal to the drive circuit 2 to rotate by one step angle, and sets the power switching circuit 3 to a high power state. Next, a data string 6a for controlling the drive circuit 2 and a data string 6b for controlling the power switching circuit 3
Compare Tai and Tbi, and if Tai > Tbi, Tbi milliseconds; if Ta1 (Tbi, then Tai milliseconds), then if Tai < Tbi, proceed to the next pulse processing.High speed In this state, the high power state continues, as shown in the center of Figure 2.Ta1) TbI
If so, the power switching circuit 3 is set to a low power state, and ('rb
iTa1) After milliseconds have elapsed, the process moves on to the next pulse. This is the state when the speed is low, and the high power state and low power state are alternately repeated as at both ends of the 21st mb.

As a result, during low-speed rotations when power consumption is high and there is sufficient torque margin, the power consumption is suppressed by switching the power, and during high-speed rotations when power consumption is low and there is not much torque margin, sufficient power is supplied to generate torque. As shown in FIG. 2e, the amount of power consumed during the period from startup to acceleration, maximum speed, deceleration, and stopping can be kept almost constant. FIG. 2d represents the average power supplied to the stepping motor 1 without power switching.

As described above, according to this embodiment, there is provided a power switching circuit capable of switching the power supplied to the step motor in two or more stages;
By providing a data string that determines the timing of switching the power of the power switching circuit, it is possible to control the average power consumed by the step motor so that it is almost constant from a low speed rotation state to a both speed rotation state. The power supplied to the step motor can be used effectively, and a complicated power supply circuit is not required. In addition, to increase speed, even if the power supplied to increase the rotation at high speeds is increased, the power at low speeds will not exceed the power capacity of the step motor, so an inexpensive step motor is used. be able to. Furthermore, since the electric power supplied to the step motor can be arbitrarily changed, the torque of the step motor can be controlled, allowing fine control that is impossible with conventional step motor drive devices.

In this embodiment, the power switching circuit 3 switches the power in two stages, but the power switching circuit 3 may include a two-voltage power supply and switch the voltage in two stages.

Effects of the Invention As described above, the present invention provides a step motor, a drive circuit for driving the step motor, a power switching circuit capable of switching power supplied to the step motor into two or more stages, and the first drive circuit. A first data string representing the pulse interval of the driving pulse applied to the power switching circuit and a second data string determining the timing for switching the power of the power switching circuit,
By providing a control device that controls the drive circuit and the power switching circuit, the step motor can be driven at high speed without using an expensive step motor with a large current capacity and a complicated and expensive power supply circuit. Since fine control can be achieved by controlling the torque of the step motor, it has great industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a step motor drive device according to an embodiment of the present invention, FIG. 2 is a waveform diagram of its main parts, FIG. 3 is a time chart for explaining the operation of the step motor drive device of this embodiment, and FIG. FIG. 4 is a block diagram of a conventional step motor drive device, and FIG. 5 is a time chart showing excitation phase switching timing of the conventional step motor drive device. DESCRIPTION OF SYMBOLS 1...Step motor, 2...Drive circuit, 3...Power switching circuit, 4...Control circuit, 6...Storage device 0 Name of agent Patent attorney Toshio Nakao and 1 other person 1st
Cause

Claims (1)

[Claims] a step motor, a drive circuit that drives the step motor, a power switching circuit capable of switching power supplied to the step motor into two or more stages, and first data representing a pulse interval of drive pulses applied to the drive circuit. a first storage means for storing a second data row that determines the timing of switching power to the power switching circuit;
A step motor drive device comprising: a control device that controls the drive circuit and the power switching circuit using the data string and the second data string stored in the second storage means.